The weight-bearing scanogram technique provides better coronal limb alignment than the navigation technique in open high tibial osteotomy

Development of an automatic surgical planning system for high tibial osteotomy using artificial intelligence

BACKGROUND

This study proposed an automatic surgical planning system for high tibial osteotomy (HTO) using deep learning-based artificial intelligence and validated its accuracy. The system simulates osteotomy and measures lower-limb alignment parameters in pre- and post-osteotomy simulations.

METHODS

A total of 107 whole-leg standing radiographs were obtained from 107 patients who underwent HTO. First, the system detected anatomical landmarks on radiographs. Then, it simulated osteotomy and automatically measured five parameters in pre- and post-osteotomy simulation (hip knee angle [HKA], weight-bearing line ratio [WBL ratio], mechanical lateral distal femoral angle [mLDFA], mechanical medial proximal tibial angle [mMPTA], and mechanical lateral distal tibial angle [mLDTA]). The accuracy of the measured parameters was validated by comparing them with the ground truth (GT) values given by two orthopaedic surgeons.

RESULTS

All absolute errors of the system were within 1.5° or 1.5%. All inter-rater correlation confidence (ICC) values between the system and GT showed good reliability (>0.80). Excellent reliability was observed in the HKA (0.99) and WBL ratios (>0.99) for the pre-osteotomy simulation. The intra-rater difference of the system exhibited excellent reliability with an ICC value of 1.00 for all lower-limb alignment parameters in pre- and post-osteotomy simulations. In addition, the measurement time per radiograph (0.24 s) was considerably shorter than that of an orthopaedic surgeon (118 s).

CONCLUSION

The proposed system is practically applicable because it can measure lower-limb alignment parameters accurately and quickly in pre- and post-osteotomy simulations. The system has potential applications in surgical planning systems.

Effect of Meniscal Tear Patterns and Preoperative Cartilage Status on Joint Space Width After Medial Opening-Wedge High Tibial Osteotomy

BACKGROUND

Medial opening-wedge high tibial osteotomy (MOWHTO) is performed to treat young adults with medial compartment knee osteoarthritis associated with varus deformity. However, factors influencing joint space width (JSW) vary according to the type of medial meniscal tear and have not yet been completely elucidated.

PURPOSE

To examine changes in JSW according to the type of medial meniscal tear after MOWHTO and analyze the influencing factors.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This study was conducted on 134 patients who underwent MOWHTO for medial osteoarthritis and were followed up for >2 years. The patients were classified into 3 groups based on medial meniscal status: intact, nonroot tear, and root tear. The authors then measured the JSW preoperatively and at 3 months, 6 months, 1 year, and >2 years postoperatively; analyzed whether the change in JSW varied according to meniscal status; and determined the association of these changes with the preoperative cartilage grade of the medial femoral condyle (MFC) and medial tibial plateau (MTP). International Knee Documentation Committee (IKDC) scores were used to evaluate clinical function.

RESULTS

Of the 134 patients, the medial meniscus was intact in 29 patients, a nonroot tear was observed in 58 patients, and a root tear was observed in 47 patients. Postoperatively, JSW increased for all groups, but the timing of the increase varied between the groups (P < .001). JSW increased the most 6 months postoperatively in the intact group and 3 months postoperatively in the nonroot tear and root tear groups (P < .001). Additionally, the increase in JSW was the greatest in the root tear group. Preoperatively, MFC and MTP cartilage status differed among the groups; MTP status did not affect the JSW, but MFC status did (P < .001). The IKDC score increased from the preoperative to postoperative time point in all groups, but there was no significant difference between groups.

CONCLUSION

The authors observed that the amount and timing of increase in JSW were dependent on the pattern of medial meniscal tear observed when MOWHTO was performed. In addition, the cartilage grade of MFC before surgery was associated with changes in JSW. The IKDC score was not significantly different between groups. However, a longer follow-up period is needed to analyze the correlation with the meniscal tear pattern and JSW.

Medial opening-wedge high tibial osteotomy with microfracture in treatment of varus medial compartmental knee osteoarthritis: clinical outcomes and second-look arthroscopic results

Objective: This study aimed to investigate the clinical outcomes of medial opening high tibial osteotomy (MOWHTO) combined with arthroscopic microfracture in the treatment of varus medial compartmental knee osteoarthritis and to assess cartilage regeneration using second-look arthroscopy. Methods: This study involved 86 patients (86 knees) who underwent MOWHTO and microfracture from August 2016 to August 2020, including 15 men and 71 women with an average age of 55.3 ± 7.6 years (range, 42-71 years). The patients underwent a second-look arthroscopy to evaluate the status of cartilage regeneration at the time of plate removal, an average of 2 years after the initial osteotomy. Clinical and radiological examinations were performed preoperatively and at the final follow-up visit. The radiologic evaluation included the weight-bearing line ratio (WBL ratio), mechanical femorotibial angle (FTA), medial proximal tibial angle (MPTA), posterior tibial slope angle (PTS) and Kellgren-Lawrence (KL) grade. Clinical outcomes were assessed using the Knee Society score (KSS) and International Knee Documentation Committee (IKDC) scores. Arthroscopic findings were assessed by macroscopic evaluation of cartilage repair according to the International Cartilage Repair Society (ICRS) grading system. Results: The mean KSS and IKDC scores significantly improved at the final follow-up compared to the scores obtained preoperatively (p < 0.05). At the time of plate removal, a second-look arthroscopic examination showed that the ICRS grade of the medial femoral condyle was as follows: grade I -11 cases, grade II -56, grade III-12, and grade IV-7, and cartilage regeneration was seen in 85% of knees (73/86). The ICRS grade of medial tibial plateau was grade I-12 cases, grade II-44, grade III-22, and grade IV-8, and cartilage regeneration was seen in 63% of knees (54/86). Significant differences were observed between cartilage regeneration and clinical outcomes (p < 0.05). Clinical results were better in the good cartilage regeneration group (grades I and II) than were in the poor cartilage regeneration group (grades III and IV). Conclusion: MOWHTO combined with arthroscopic microfracture can effectively improve clinical outcomes in the treatment of varus medial compartmental knee osteoarthritis. Cartilage regeneration can be promoted by correcting varus deformities, which affect clinical outcomes.

Editorial Commentary: Alignment for Open-Wedge High Tibial Osteotomy Can Be Planned Using the Hip-Knee-Ankle Angle and the Weightbearing Line

Correct alignment of the limb mechanical axis is a principal goal of open-wedge high tibial osteotomy and determines successful postoperative outcomes. Excessive postoperative joint line obliquity must be avoided. A mechanical medial proximal tibial angle (mMPTA) less than 95° results in poor outcomes. Preoperative planning is commonly performed using a picture archiving and communication system; however, this is time-consuming and sometimes inaccurate because many landmarks and parameters need to be confirmed manually. Hip-knee-ankle (HKA) angle and weightbearing line (WBL) percentage are perfectly correlated to the Miniaci angle when planning open-wedge high tibial osteotomy, and ΔmMPTA and ΔWBL percentage are nearly perfectly correlated with the ΔHKA angle. Surgeons can easily measure the Miniaci angle according to the preoperative HKA and preoperative WBL percentage without digital software, and mMPTA greater than 95° can be avoided. Finally, bony and soft tissue components must be considered during preoperative planning. Medial soft tissue laxity must be specifically avoided.

Does Generalized Joint Laxity Affect Postoperative Alignment and Clinical Outcomes Following Medial Opening-Wedge High Tibial Osteotomy?

BACKGROUND

The purpose of this study was to investigate whether generalized joint laxity affects the postoperative alignment and clinical outcomes of medial opening-wedge high tibial osteotomy (MOWHTO).

METHODS

A total of 198 patients who underwent MOWHTO was divided into two groups according to absence or presence of generalized joint laxity. Generalized joint laxity was measured using the Beighton and Horan criteria, and a score of 4 or more out of 9 was defined as generalized joint laxity. A weight bearing line (WBL) ratio of 55% to 70% was considered an acceptable postoperative lower limb alignment range; WBL over 70% was defined as overcorrection and less than 55% as undercorrection. The WBL ratio was investigated before and 2 years after surgery, and the Western Ontario McMaster University Osteoarthritis Index scale score (WOMAC) was evaluated for patient-reported outcomes (PRO) of MOWHTO. There were 147 (73.7%) patients in the nongeneralized joint laxity group and 51 (26.3%) in the generalized joint laxity group. Preoperatively, there was no difference between the two groups in hip-knee-ankle (HKA) angle or WBL ratio (all P > .05).

RESULTS

At 2 years postoperatively, the generalized joint laxity group showed significantly higher HKA angle and WBL ratio than the nongeneralized joint laxity group (all P < .05). There was a significant difference in the distribution ratio of undercorrection, normocorrection, and overcorrection patients between the two groups (P < .05). There were no differences between the two groups in preoperative and postoperative WOMAC scores (all, P > .05).

CONCLUSION

The generalized joint laxity significantly affected postoperative over correction of alignment following MOWHTO. However, there was no significant difference in PRO between the patients who did and did not have generalized joint laxity after MOWHTO until 2 years.

Ankle Pain After Medial Opening-Wedge High Tibial Osteotomy in Patients With Knee Osteoarthritis and Concurrent Ankle Osteoarthritis

BACKGROUND

Medial opening-wedge high tibial osteotomy (MOWHTO) in patients with varus knee osteoarthritis (OA) causes changes to ankle and hindfoot alignment. However, the compensatory ability of the ankle and hindfoot varies according to the severity of ankle OA.

PURPOSE

To investigate whether the changes in ankle symptoms and ankle and hindfoot alignments differ after MOWHTO according to the severity of preoperative ankle OA.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The data of 130 patients who were followed for ≥4 years were reviewed. Patients were classified into 2 groups according to their severity of ankle OA: group 1, modified Kellgren-Lawrence grade 0 and 1; group 2, grade ≥2. Four radiographic parameters were examined to evaluate ankle alignment: tibial plafond inclination, talar tilt, talar inclination, and tibial surface angle. The hindfoot alignment was evaluated using the varus-valgus angle (VVA) of the calcaneus. A visual analog scale (VAS) was used to evaluate ankle pain. The patient-reported outcome measure of the knee joint was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score.

RESULTS

There were 110 patients in group 1 and 20 patients in group 2. In group 2, the change in talar inclination after MOWHTO was significantly greater and the changes in tibial plafond inclination, talar tilt, and VVA were significantly smaller compared with in group 1 (all P < .05). Ankle pain VAS scores were more severe in group 2 than in group 1 pre- and postoperatively (all P < .05), and group 2 reported that ankle pain worsened postoperatively (P < .05). In both groups, knee WOMAC scores improved, and there were no differences between groups pre- or postoperatively (all P > .05). A multivariate regression analysis demonstrated that a small VVA change (odds ratio, 0.775; P = .027) and severe OA grade of the ankle joint preoperatively (Kellgren-Lawrence grades 2-4 vs 0 and 1; odds ratio, 4.241 [P = .046]) predicted increased ankle pain VAS scores after MOWHTO.

CONCLUSION

Although the patient-reported outcome measures for the knee joint improved irrespective of the presence of ankle OA, ankle pain worsened after MOWHTO in patients with ankle OA. Inadequate compensatory change in hindfoot alignment increased ankle pain in these patients.

Insufficient Correction and Preoperative Medial Tightness Increases the Risk of Varus Recurrence in Open-Wedge High Tibial Osteotomy

PURPOSE

To assess serial changes of limb alignment after open wedge high tibial osteotomy (HTO) using the weightbearing line (WBL) ratio in the midterm, with a focus on varus recurrence.

METHODS

Patients undergoing open wedge HTO from January 2010 to December 2016 were retrospectively reviewed. Those without serial postoperative weightbearing long-leg alignment films, those who showed remained varus alignment after osteotomy, and those who had <2 years of follow-up were excluded. In terms of immediate postoperative limb alignment (≤3 months) measured using WBL ratio, cases were categorized into 4 groups: <50%, undercorrection; 50% to 57%, insufficient correction; 57% to 67%, planned correction; and >67%, overcorrection. To determine risk factors for varus recurrence (WBL ratio <50%), immediate postoperative WBL ratio category and preoperative valgus and varus stress angles (which represent medial and lateral tightness of the joint, respectively) were investigated using logistic regression analysis, taking other related factors into account. Clinical outcomes according to varus recurrence were measured using Hospital for Special Surgery (HSS) scores.

RESULTS

A total of 148 cases were included. Varus recurrence was noted in 40 cases (27.0%), with a mean follow-up of 49.7 ± 21.8 months (range 24 to 102 months). The incidence of varus recurrence was different according to WBL ratio category: 10/10 (100.0%) in undercorrection; 16/33 (48.5%) in insufficient correction; 13/58 (22.4%) in planned correction; and 1/47 (2.1%) in overcorrection. Based on logistic regression analysis, insufficient correction and preoperative valgus stress angle were found to be significant risk factors (P = .038, and .008, respectively). With valgus stress angle <2°, 7 of 10 insufficient correction cases showed varus recurrence (P = .005). However, HSS scores did not differ according to varus recurrence (P = .363).

CONCLUSION

Insufficient correction and preoperative medial tightness increased the risk of varus recurrence. Especially in cases where preoperative valgus stress angle was <2°, insufficient correction was strongly associated with varus recurrence. However, no significant differences in clinical outcomes were observed according to varus recurrence in the midterm.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Poor Accuracy of Intraoperation Medial Proximal Tibial Angle Measurement Compared to Alignment Rod Methods in Open-Wedge High Tibial Osteotomy for Medial Knee Osteoarthritis

The alignment rod is widely used as an index for intraoperative alignment but alignment error is inevitable. The purpose of this study was to verify the accuracy of lower limb alignment correction by measurement of mechanical medial proximal tibial angle (MPTA) as an index in open-wedge high tibial osteotomy (OWHTO). This study was retrospective case series. This study involved 152 patients undergoing OWHTO for primary medial osteoarthritis. Alignment rod or MPTA measurement board was used as an index of optimal correction in OWHTO. Alignment rod was used from October 2013 to May 2017, and MPTA measurement board was used from June 2017 to April 2020. The correction using an alignment rod was that the weight-bearing line ratio (WBLR) passed through 62.5% of the tibial plateau which was defined as Fujisawa's point under intraoperative fluoroscopy (A rod group). The correction using MPTA measurement board was aligning the intraoperative MPTA to the preplanned angle (MPTA group). Preplanned optimal alignment was defined as Fujisawa's point in all patients. Knee injury and osteoarthritis outcome measure (KOOS), Knee Society scoring system objective knee score (KSS), 3-m timed up-and-go test (TUG), single-limb standing test (SLS), and isometric muscle strength of quadriceps and hamstrings were assessed as clinical results. WBLR, MPTA, joint-line convergence angle (JLCA), and joint-line obliquity (JLO) were assessed as radiological results preoperatively and at 1 year after surgery. The clinical and radiological results after OWHTO were compared with both groups. Postoperative WBLR in A rod group was closer to the target alignment (Fujisawa's point: 62.5) than in the MPTA group at all stage (A rod group vs. MPTA group: 63.1 vs. 54.6 at 6 months; 62.0 vs. 53.4 at 1 year; p < 0.001). There were no significant differences in the clinical results between both groups. The intraoperative measurement of medial proximal tibial angle has a risk of undercorrection after OWHTO. His study is a retrospective case series and reflects level of evidence IV.

Extent of Preoperative Medial Meniscal Extrusion Influences Intermediate-Term Outcomes After Medial Opening-Wedge High Tibial Osteotomy

BACKGROUND

The purpose of the present study was to determine the relationship between preoperative medial meniscal extrusion, as classified according to magnetic resonance imaging (MRI), and medial opening-wedge high tibial osteotomy outcomes at intermediate-term follow-up.

METHODS

We reviewed the records for 212 patients who had undergone medial opening-wedge high tibial osteotomy for the treatment of medial compartment osteoarthritis between January 2009 and September 2014, with a minimum duration of follow-up of 5 years. Patients were divided into 2 groups according to the presence of pathologic medial meniscal extrusion (>3 mm). Moreover, patients were divided into 4 groups according to MRI Osteoarthritis Knee Score (MOAKS) criteria and relative medial meniscal extrusion values. Associations between the extent of preoperative medial meniscal extrusion and clinical outcomes over a mean duration of follow-up of 8.1 years were evaluated with use of Spearman rank correlation analysis. Regression analyses were performed to determine preoperative characteristics relevant to medial meniscal extrusion. Clinical outcomes were assessed with use of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Tegner activity scale score.

RESULTS

Postoperative KOOS pain scores were significantly different in the pathologic and non-pathologic medial meniscal extrusion groups (69.9 ± 18.0 versus 79.2 ± 11.4, respectively; p < 0.001). Additionally, the degree of preoperative medial meniscal extrusion based on both classification methods and the postoperative KOOS pain score were significantly correlated (r = -0.404 and -0.364; p < 0.001). Despite the inferior clinical outcomes associated with greater preoperative medial meniscal extrusion, medial opening-wedge high tibial osteotomy was associated with significant improvement in all outcome measures between the preoperative and latest follow-up assessments (p < 0.001). Preoperative meniscal patterns, including horizontal flap, complex, and root tears (p = 0.001), and increased Kellgren-Lawrence grade (p < 0.001) were related to the severity of medial meniscal extrusion. The survival rate was 94.8% at a mean of 8.1 years, and survival was not associated with the grade of medial meniscal extrusion as assessed with either classification scheme.

CONCLUSIONS

At intermediate-term follow-up, greater preoperative medial meniscal extrusion was related to inferior postoperative clinical outcomes, specifically pain, after medial opening-wedge high tibial osteotomy. Despite the inferior results associated with preoperative medial meniscal extrusion, medial opening-wedge high tibial osteotomy was associated with a satisfactory survival rate after a mean of 8.1 years, regardless of the extent of medial meniscal extrusion.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

How to achieve an optimal alignment in medial opening wedge high tibial osteotomy?

Medial opening wedge high tibial osteotomy (MOWHTO) is a widely used surgical treatment option for medial compartmental osteoarthritis with varus deformity. It is important that proper lower limb alignment is achieved. However, there has been no consensus about an optimal alignment in MOWHTO. Most studies suggest that achieving valgus alignment is necessary, and recent studies support slight valgus mechanical alignment of less than 3° of mechanical femorotibial angle. Overcorrection and undercorrection is not recommended for achieving good surgical outcomes. To prevent undercorrection and overcorrection in MOWHTO, the method of placing the weight-bearing line in the target range must be precise. There are several ways to place a weight-bearing line within the target range. While the most important factor for a successful MOWHTO is achieving an ideal mechanical axis correction, there are a few other factors to consider, including joint line obliquity, posterior tibial slope, ligament balancing, and patellar height. Several factors exist that lead to undercorrection and overcorrection. Preoperative amount of varus deformity, lateral hinge fracture, and fixation failure can result in undercorrection, while medial soft tissue laxity and the amount of correction angle and target point beyond hypomochlion can result in overcorrection. This study aimed to review the literature on optimal alignment in MOWHTO and report on the factors to be considered to prevent correction errors and how to achieve an optimal alignment.

CAS and PSI increase coronal alignment accuracy and reduce outliers when compared to traditional technique of medial open wedge high tibial osteotomy: a meta-analysis

PURPOSE

Medial open-wedge high tibial osteotomy (MOWHTO) is an accepted option in the treatment of medial compartment osteoarthritis of the knee in young and active patients. Functional results are closely correlated to the correction of the mechanical axis of the lower limb. Although several angular and geometrical methods and values have been proposed in the past, the ideal target is still debated. In addition, it is important to have a deep correlation between the planned correction and the achieved correction after surgery. The aim of the present systematic review was to identify the ideal coronal correction after MOWHTO and the most accurate method to achieve it.

METHODS

A systematic review of the literature was completed on July 3rd 2020 in the Pubmed, Medline, Cochrane Reviews, and Google Scholar databases using the Medical Subject Headings (MeSH) terms: "high tibial osteotomy" AND "accuracy" OR "planning".

RESULTS

28 studies were included; 18 were focused on computer-assisted surgery (CAS) and 10 on patient-specific instrumentation (PSI). There were 598 patients in the CAS group and 501 in the control group; the rate of outliers was 16% and 38.2% respectively (P = 0.04), while there was no significant difference between the two groups (SMD = - 0.10; 95% CI 1.31 to 1.12; P = n.s.) in terms of coronal accuracy. Likewise, there were 318 patients in the PSI group and 40 in the control group; the rate of outliers was 15% and 40% respectively (P = 0.98), while there was no significant difference between the two groups (SMD = 0.01; 95% CI 0.58 to 0.59; P = 0.98).

CONCLUSIONS

A statistically significant reduced outlier rate and a non-significant increased accuracy emerged with the use of CAS when compared to the traditional surgical technique, whereas the results of PSI were still inconclusive. In addition, it emerged clearly that no consensus still exists on the ideal correction target to be achieved after surgery.

LEVEL OF EVIDENCE

III.

Role of imaging in surgical decision making in young knee osteoarthrosis

Osteoarthrosis is the most common form of knee arthritis, characterized by pain and discomfort from primarily articular cartilage wear. Traditionally in its end stage, it has been treated with total knee arthroplasty, a permanent process with a life span of ten to fifteen years and challenges with revision. With an increasing longevity and epidemic of obesity that the population is facing, naturally, we are seeing more and more patients with osteoarthrosis at a younger age. This makes it imperative to extend the life of the native knee by conservative measures, injections of steroid, hyaluronic acid, or biologicals and finally a slew of surgical alternatives ranging from joint realignment to partial and total joint replacement. Besides the clinical presentation, decisions are made based on joint alignment, extent and degree of cartilage wear and the status of the subchondral bone. Imaging plays an invaluable role in surgical decision making. In this article, we will discuss how imaging is used in our practice during decision making for the management of the young osteoarthritic knee.

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Prevalence of knee osteoarthrosis is increasing in younger population.

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Surgical treatment of osteoarthrosis at a younger age has its own challenges of need to return to higher levels of physical activity and longer life expectancy.

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Osteoarthrosis is now considered a whole organ dynamic disease.

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Imaging plays an important role in decision making in treatment and management of osteoarthrosis.

A Systematic Review on Selected Complications of Open-Wedge High Tibial Osteotomy from Clinical and Biomechanical Perspectives

Background

The wedge opened during high tibial osteotomy defines the alignment correction in different body planes and alters soft tissue insertions. Although multiple complications of the surgery can be correlated to this, there is still a lack of consensus on the occurrence of those complications and their cause. The current study is aimed at clarifying this problem using a combined medical and biomechanical perspective.

Methods

We conducted a systematic review of the literature on selective complications of the surgery correlated with the angles of the opened wedge. Search topics covered tibial slope alteration, patellar height alteration, medial collateral ligament release, and model-based biomechanical simulations related to surgical planning or complications. Findings. The selection process with the defined inclusion/exclusion criteria led to the collection of qualitative and quantitative data from 38 articles. Medial collateral ligament tightness can be a valid complication of this surgery; however, further information about its preoperative condition seems required for better interpreting the results. The posterior tibial slope significantly increases, and the patellar height (using the Blackburne-Peel ratio) significantly decreases in the majority of the selected studies. Model-based biomechanical studies targeting surgical planning are mostly focused on the lower-limb alignment principles and tibiofemoral contact balancing rather than surgical complications. Interpretation. Increased posterior tibial slope, patellar height decrease, and medial collateral ligament tightness can occur due to alterations in different body planes and in soft tissue insertions after wedge opening. This study clarified that information about preoperative alignment in all body planes and soft-tissue conditions should be considered in order to avoid and anticipate these complications and to improve per surgery wedge adaptation. The findings and perspective of this review can contribute to improving the design of future clinical and biomechanical studies.

Evaluation of the reliability of lower extremity alignment measurements using EOS imaging system while standing in an even weight-bearing posture

This study aimed to analyze the reproducibility and reliability of the alignment parameters measured using the EOS image system in both limbs while standing with an even weight-bearing posture. Overall, 104 lower extremities in 52 patients were analyzed retrospectively. The patients stood with an even load over both lower extremities then rotated 15° in both directions. Two EOS images were acquired and 104 pairs of lower extremities were compared according to the position of the indexed lower extremities. Then, the inter-observer reliability of the EOS system and the inter-modality reliability between EOS and computed tomography (CT) were evaluated. Femoro-tibial rotation (FTR) and tibial torsion demonstrated a significant difference between the anterior and posterior positions of the indexed lower extremity. In the inter-observer reliability analysis, all values except for FTR and tibial torsion demonstrated good or very good reliability. In the anterior position, FTR demonstrated moderate, and tibial torsion demonstrated poor reliability. In the posterior position, both FTR and tibial torsion demonstrated poor reliability. In the reliability analysis between the three-dimensional (3D) EOS model and 3D CT images, all measurements of the femur demonstrated very good reliability, but measurements of the tibia did not. For the coronal and sagittal alignment parameters measured by the EOS 3D system with rotated standing posture, except for the measurement including tibial torsion., there were no significant difference for either position of the indexed extremities with high agreement between the observers as well as with the CT 3D model.

Second-look arthroscopic cartilage status is related to intermediate-term outcomes after medial opening-wedge high tibial osteotomy

AIMS

To determine the relationship between articular cartilage status and clinical outcomes after medial opening-wedge high tibial osteotomy (MOHTO) for medial compartmental knee osteoarthritis at intermediate follow-up.

METHODS

We reviewed 155 patients (155 knees) who underwent MOHTO from January 2008 to December 2016 followed by second-look arthroscopy with a mean 5.3-year follow-up (2.0 to 11.7). Arthroscopic findings were assessed according to the International Cartilage Repair Society (ICRS) Cartilage Repair Assessment (CRA) grading system. Patients were divided into two groups based on the presence of normal or nearly normal quality cartilage in the medial femoral condyle: good (second-look arthroscopic) status (ICRS grade I or II; n = 70), and poor (second-look arthroscopic) status (ICRS grade III or IV; n = 85) groups at the time of second-look arthroscopy. Clinical outcomes were assessed using the International Knee Documentation Committee (IKDC) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and 36-Item Short Form survey.

RESULTS

Significant improvements in all clinical outcome categories were found between the preoperative and second-look arthroscopic assessments in both groups (p < 0.001). At the latest follow-up, the mean IKDC and WOMAC scores in the good status group further improved compared with those at the time of second-look arthroscopic surgery (p < 0.001), which was not shown in the poor status group. The mean IKDC (good status, 72.8 (SD 12.5); poor status, 64.7 (SD 12.1); p = 0.002) and mean WOMAC scores (good status, 15.7 (SD 10.8); poor status, 21.8 (SD 13.6); p = 0.004) significantly differed between both groups at the latest follow-up. Moreover, significant correlations were observed between ICRS CRA grades and IKDC scores (negative correlation; p < 0.001) and WOMAC scores (positive correlation; p < 0.001) at the latest follow-up. Good cartilage status was found more frequently in knees with the desired range of 2° to 6° valgus correction than in those with corrections outside this range (p = 0.019).

CONCLUSION

Second-look arthroscopic cartilage status correlated with clinical outcomes after MOHTO at intermediate-term follow-up, despite the relatively small clinical differences between groups. Cite this article: Bone Joint J 2021;103-B(11):1686-1694.

Unstable Lateral Hinge Fracture or Occult Complete Osteotomy Adversely Affects Correction Accuracy in Open-Wedge High Tibial Osteotomy

PURPOSE

To verify whether lateral hinge fracture (LHF) affects correction accuracy in open-wedge high tibial osteotomy (OWHTO) and to identify the fracture characteristics responsible for inaccurate correction, including LHF type and hinge location.

METHODS

Patients undergoing OWHTO with locking plate fixation between 2010 and 2016 were retrospectively reviewed. Patients who did not have a minimum 2-year of follow-up or postoperative long-standing hip-to-ankle radiographs were excluded. Correction accuracy was assessed using the weight-bearing line ratio: 57% to 67%, planned correction; 50% to 70%, acceptable correction; otherwise, inappropriate correction. The association between LHF and correction accuracy was assessed using the χ² test. To identify the fracture characteristics responsible for inaccurate correction, LHF type (stable type 1 and unstable types 2 and 3) and hinge location (shallow osteotomy, deep osteotomy, and occult complete osteotomy) were analyzed using ordinal logistic regression analysis, taking other related demographic and radiologic factors into account. Clinical outcomes according to LHF type were evaluated using the Hospital for Special Surgery scores.

RESULTS

A total of 148 cases were included; 41 (27.7%) showed LHF: type 1, 32 cases; type 2, 7 cases; and type 3, 2 cases. Planned, acceptable, and inappropriate corrections were noted in 63 (42.6%), 36 (24.3%), and 48 (32.4%) cases, respectively. LHF had a significant association with correction accuracy (P = .010). Regarding fracture characteristics, unstable LHF and occult complete osteotomy were significant risk factors (P = .016 and P = .004, respectively). Specifically in cases of stable LHF, occult complete osteotomy adversely affected correction accuracy (P = .025). No difference was found in the final Hospital for Special Surgery scores according to LHF type (P = .816).

CONCLUSIONS

LHF affected the accuracy of coronal alignment correction in OWHTO. Unstable LHF or occult complete osteotomy were risk factors for inaccurate correction. Even among stable LHFs, those with occult complete osteotomy could lead to inaccurate correction.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Reliability of Preoperative Planning Method That Considers Latent Medial Joint Laxity in Medial Open-Wedge Proximal Tibial Osteotomy

Background:

Soft tissue laxity around the knee joint has been recognized as a crucial factor affecting correction error during medial open-wedge proximal tibial osteotomy (MOWPTO). Medial laxity in particular, which represents the changes in joint-line convergence angle (JLCA), affects soft tissue correction.

Purpose:

The purpose of this study was to quantify medial laxity and develop a preoperative planning method that considers medial laxity.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study retrospectively reviewed 139 knees in 117 patients who underwent navigation-assisted MOWPTO from January 2014 to July 2019 for symptomatic medial compartment osteoarthritis with varus alignment >5°. We compared the results of 2 preoperative planning methods: conventional Miniaci (n = 47) and latent medial laxity reduction (LMLR) (n = 92). We evaluated the incidence of undercorrection, acceptable correction, and overcorrection. The radiologic parameters were analyzed using multiple linear regression with a stepwise selection model to establish an equation for the optimal preoperative planning method. The intraclass correlation coefficients (ICCs) of intraobserver, interobserver, and intermethod reliability were calculated.

Results:

The Miniaci method showed a higher incidence of overcorrection (55.3%) than the LMLR method (22.8%) at postoperative 6 months (P = .0006). Multiple linear regression with a stepwise selection model revealed a high correlation coefficient (R² = 0.888) for the following equation: Adjusted planned correction angle = 0.596 + 0.891 × Target correction angle – 0.255 × ΔJLCA_valgus. Upon simplification, the following equation showed the highest intermethod ICC value (0.991): Target correction angle – ⅓ΔJLCA_valgus, while the Miniaci method showed a relatively low ICC value of 0.875.

Conclusion:

There was a risk of overcorrection after MOWPTO using the conventional Miniaci method. An equation that considers medial laxity may help during preoperative planning for optimal correction during MOWPTO.

Focal proximal fibular angle: A potential indicator of the tibial mechanical axis in opening-wedge high tibial osteotomy

BACKGROUND

For opening-wedge high tibial osteotomy, correct alignment is essential for a better prognosis. It is difficult to evaluate the mechanical axis of the lower extremity or tibia using a single fluoroscopic image. This study aimed to discuss the use of focal proximal fibular angle (FPFA), which can be assessed by a single fluoroscopic image, as an intraoperative indicator.

METHODS

Eligible for analyses were 111 consecutively treated patients; for the final analyses 96 patients were included. The preoperative and postoperative medial proximal tibial angle (MPTA) and FPFA were measured. The relationship between these two angles, correction amount, weight-bearing line ratio and patient characteristics were analyzed.

RESULTS

The preoperative FPFA and MPTA were 96.5 ± 3.8° (mean ± standard deviation, SD) and 84.8 ± 3.0°, while the postoperative FPFA and MPTA were 87.6 ± 4.1° and 94.0 ± 3.5°, respectively. The preoperative and postoperative sums of the MPTA and FPFA were constant. The discrepancy was less than 3° in all knees, less than 2° in 92.7% knees and less than 1° in 68.8% knees. It was not correlated with age, sex, weight-bearing line ratio, or correction amount.

CONCLUSION

The study findings confirmed the constancy of the sum of the MPTA and FPFA. The FPFA can be easily evaluated on a single fluoroscopic image of the knee. Use of the FPFA as guidance may simplify the procedure of opening-wedge high tibial osteotomy and approximately predict the tibial mechanical axis.

Alignment adjustment using the Valgus stress technique can increase the surgical accuracy of novice surgeons during medial opening-wedge high Tibial osteotomy

Background

The purpose of this study was to compare the degree of accuracy of coronal alignment correction with use of the “alignment adjustment under valgus stress technique” between expert and novice surgeons during medial opening-wedge high tibial osteotomy (MOWHTO).

Methods

Forty-eight patients who underwent MOWHTO performed by an expert surgeon (expert group) and 29 by a novice surgeon (novice group) were enrolled in analysis. During surgery, lower-extremity alignment was corrected using the “alignment adjustment under valgus stress technique”. Normocorrection was defined as a weight-bearing line ratio between 55 and 70% and the correction accuracy was compared between expert and novice groups using the ratio of normocorrection to outliers. The clinical outcomes were also compared using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 1 year after surgery.

Results

The undercorrection rate was 14.6% in the expert group and 13.8% in the novice group, while the overcorrection rate was 2.1% in the expert group and 3.4% in the novice group. In the ratio of normocorrection to outliers, no difference was found between the two groups at the one-year follow-up visit (83.3% in the expert group vs. 82.8% in the novice group; p > 0.05). Also, no significant differences were seen in WOMAC subscores immediately preoperatively and at 1 year after surgery (all p > 0.05).

Conclusion

Adhering to the “alignment adjustment under valgus stress technique” protocol enabled novice surgeons to achieve similar surgical accuracy as that of an expert surgeon in coronal alignment during MOWHTO.

Level of evidence

Level III.

Osteotomy around the knee is planned toward an anatomical bone correction in less than half of patients

INTRODUCTION

In cases where the femur or tibial deformity is not correctly analysed, the corrective osteotomies may result in an oblique joint line. The aim of this study was to assess the preoperative deformity of patients due to undergo corrective osteotomy and the resulting abnormal tibial and femoral morphologies after the planned correction using 3D software.

METHODS

CT scans of 327 patients undergoing corrective osteotomy were retrospectively included. Each patient was planned using a software application and the simulated correction was validated by the surgeon. Following the virtual osteotomy, tibial and femoral coronal angular values were considered abnormal if the values were outside 97.5% confidence intervals for non-osteoarthritis knees. After virtual osteotomy, morphological abnormalities were split into two types. Type 1 was an under/overcorrection at the site of the osteotomy resulting in abnormal bone morphology. A type 2 was defined as an error in the site of the correction, resulting in an uncorrected abnormal bone morphology.

RESULTS

The global rate of planned abnormalities after tibial virtual osteotomy was 50.7% (166/327) with abnormalities type 1 in 44% and type 2 in 6.7%. After femoral virtual osteotomy the global rate was 6.7% (22/327) with only abnormalities type 1. A lower preoperative HKA was significantly associated with a non-anatomical correction (R²=0.12, p<0.001) for both femoral (R²=0.06, p<0.001) and tibial (R²=0.07, p<0.001) abnormalities.

CONCLUSION

Non-anatomical correction was found in more than half the cases analysed more frequently for preoperative global varus alignment. These results suggest that surgeons should considered anatomical angular values to avoid joint line obliquity.

LEVEL OF EVIDENCE

III; retrospective cohort study.

Change of joint-line convergence angle should be considered for accurate alignment correction in high tibial osteotomy

Background

The alignment correction after high tibial osteotomy (HTO) is made both by bony correction and soft-tissue correction around the knee. Change of the joint-line convergence angle (JLCA) represents the soft-tissue correction after HTO, which is the angle made by a tangential line between the femoral condyles and the tibial plateau. We described the patterns of JLCA change and related factors after HTO and investigated the appropriate preoperative planning method.

Methods

Eighty patients who underwent HTO between 2013 and 2016 were included for this retrospective study. Standing, whole-limb radiograph, supine knee anteroposterior (AP) and lateral were measured on the preoperative and postoperative radiographs. The patterns of JLCA changes and related factors were analyzed.

Results

JLCA decreased by a mean of 0.9° ± 1.2° (P < 0.001) after HTO. Sixteen patients (20%, group II) showed a greater JLCA decrease ≥ 2°, while 64 (80%, group I) patients remained in a narrow range of JLCA change < 2°. Group II showed more varus deformity (varus 8.1° vs. varus 4.7° in the mechanical femorotibial angle, P < 0.001), greater JLCA on standing (4.9° vs. 2.1°, P < 0.001), and the difference of JLCA in the standing and supine positions (2.8° vs. 0.7°, P < 0.001) preoperatively compared to group I. The risk of a greater JLCA decrease ≥ 2° was associated with greater preoperative JLCA in the standing position and the difference between the JLCA in the standing and supine positions. Postoperative JLCA correlated better with preoperative JLCA in the supine position than those in the standing position. A preoperative JLCA ≥ 4° or the difference of preoperative JLCA in the standing and supine positions ≥ 1.7° was the cut-off value to predict a large JLCA decrease ≥ 2° after HTO in the receiver operating characteristic (ROC) curve analysis.

Conclusions

Surgeons should consider the effect of the JLCA change during the preoperative planning and intraoperative procedure to avoid unintended overcorrection.

Is patient-specific instrumentation more precise than conventional techniques and navigation in achieving planned correction in high tibial osteotomy?

INTRODUCTION

Preoperative planning in high tibial osteotomy (HTO) is a critical step for achieving the desired correction and a clinically satisfactory outcome. Conventional radiography, navigation assistance and patient-specific instrumentation (PSI) are the 3 means of planning, but no prospective studies have compared precision between the 3. The aims of the present study were: (1) to analyze and compare correction precision between the 3 planning approaches at 1 year's follow-up; (2) to compare results to those reported in the literature; and (3) to analyze factors influencing the achievement of planned correction.

HYPOTHESIS

The study hypothesis was that PSI provides more precise and reproducible planned correction than conventional methods or navigation.

MATERIAL AND METHOD

Between June 2017 and June 2018, a multicenter non-randomized prospective observational study was conducted in 11 centers. One hundred and twenty-six patients with Ahlbäck grade I, II or III idiopathic medial tibiofemoral osteoarthritis with stable knee were included and allocated to 3 preoperative planning groups: conventional (group 1), navigation (group 2) and PSI (group 3). Mean age at surgery was 51.2 years (range, 19-69 years; median, 53.2 years); 100 male, 26 female. Complete weight-bearing radiographic work-up was performed preoperatively and at 1 year's follow-up. The PSI group also underwent CT as part of guide production. Target angular correction and mechanical Hip-Knee-Ankle (HKA) axis were set preoperatively. The main endpoint was the difference between planned HKA and HKA at a minimum 12 months.

RESULTS

Mean HKA difference was 1.1±3 in group 1, 2.1±2.6 in group 2 and 0.3±3.1 in group 3. Precision was better with PSI, but not significantly when comparing all 3 groups together. On pairwise intergroup comparison, there was a significant difference only between groups 2 and 3, in favor of PSI (P=0.011).

DISCUSSION

None of the 3 techniques demonstrated superiority in achieving target correction at 1 year. The study hypothesis was thus not confirmed. All 3 techniques proved reliable and precise in HTO planning.

LEVEL OF EVIDENCE

III, prospective non-randomized comparative study.

Patient-specific prediction of joint line convergence angle after high tibial osteotomy using a whole-leg radiograph standing on lateral-wedge insole

PURPOSE

To assess the usefulness of a whole-leg radiograph standing on lateral-wedge insole (LWI) for predicting the change in joint line convergence angle (JLCA) before vs. after high tibial osteotomy (HTO).

METHODS

Forty knees with medial osteoarthritis underwent open-wedge HTO. Pre-operatively, all patients had whole-leg radiographs taken in three different conditions: supine, standing, and standing on LWI inclined at 20°. A standing whole-leg radiograph was also obtained post-operatively. Radiological measurements including JLCA and percentage of mechanical axis (%MA) were compared. Using pre-operative radiographs, correction angles were calculated with the target %MA at 62.5%. Correlations between the difference in calculated correction angle among the three pre-operative conditions and the change in JLCA before vs. after HTO were assessed.

RESULTS

In the pre-operative standing conditions, the mean JLCA of 3.8° was significantly decreased to 3.2° using LWI, which did not differ from post-operative JLCA of 3.1°. Mean %MA significantly shifted laterally from 20.6 to 24.8% using LWI, and was strongly correlated with the change in JLCA (coefficient, 0.83). Calculated correction angles differed significantly among the three pre-operative conditions. The difference in calculated correction angle between standing with and without LWI was strongly correlated to the change in standing JLCA before vs. after HTO (coefficient, 0.73).

CONCLUSION

Larger differences in calculated correction angles between pre-operative radiographs standing with and without LWI predicted larger changes in JLCA after HTO. Whole-leg radiograph standing on LWI is a promising modality for correct pre-operative planning considering patient-specific changes in JLCA before vs. after HTO.

LEVEL OF EVIDENCE

IV.

The effect of knee joint rotation in the sagittal and axial plane on the measurement accuracy of coronal alignment of the lower limb

Background

Although the measurement of coronal alignment of the lower limb on conventional full-length weight-bearing anteroposterior (FLWAP) radiographs was reported to be influenced by the knee joint rotation, no comparative analysis was performed considering the effects of knee joint rotation on the sagittal and axial planes simultaneously using the three-dimensional images while taking into account the actual weight-bearing conditions. The aim of this study was to investigate the effect of knee joint rotation on the measurement accuracy of coronal alignment of the lower limb on the FLWAP radiograph.

Methods

Radiographic images of 90 consecutive patients (180 lower limbs) who took both the FLWAP radiograph and the EOS image were retrospectively reviewed. The relationship among delta values of mechanical tibiofemoral angle (mTFA) between the FLWAP radiographs and the EOS images (ΔmTFA), knee flexion/extension angle (sagittal plane rotation) on the EOS images, and patellar rotation (axial plane rotation) on the FLWAP radiographs were analyzed. Further, subgroup analysis according to each direction of knee joint rotation was performed.

Results

There was a significant correlation between ΔmTFA and sagittal plane rotation (r = 0.368, P <  0.001), whereas axial plane rotation was not correlated. In the analysis according to the direction, statistically significant correlation was observed only in the knee flexion group (r = 0.399, P <  0.001). The regression analysis showed a significant linear relationship between ΔmTFA and sagittal plane rotation (r² = 0.136, P <  0.001). Additional subgroup analysis in patients with the patellar rotation greater than 3% showed a similar result of a linear relationship between ΔmTFA and sagittal plane rotation (r² = 0.257, P <  0.001), whereas no statistically significant relationship was found in patients with the patellar rotation less than 3%.

Conclusion

The measurement accuracy of coronal alignment of the lower limb on the FLWAP radiographs would be influenced by knee flexion, specifically when there is any subtle rotation of the knee joint in the axial plane. A strict patellar forward position without axial plane rotation of the knee could provide accurate results of the measurement even if there is a fixed flexion contracture of the knee.

High tibial osteotomy with human umbilical cord blood-derived mesenchymal stem cells implantation for knee cartilage regeneration

BACKGROUND

High tibial osteotomy (HTO) is a well-established method for the treatment of medial compartment osteoarthritis of the knee with varus deformity. However, HTO alone cannot adequately repair the arthritic joint, necessitating cartilage regeneration therapy. Cartilage regeneration procedures with concomitant HTO are used to improve the clinical outcome in patients with varus deformity.

AIM

To evaluate cartilage regeneration after implantation of allogenic human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) with concomitant HTO.

METHODS

Data for patients who underwent implantation of hUCB-MSCs with concomitant HTO were evaluated. The patients included in this study were over 40 years old, had a varus deformity of more than 5°, and a full-thickness International Cartilage Repair Society (ICRS) grade IV articular cartilage lesion of more than 4 cm² in the medial compartment of the knee. All patients underwent second-look arthroscopy during hardware removal. Cartilage regeneration was evaluated macroscopically using the ICRS grading system in second-look arthroscopy. We also assessed the effects of patient characteristics, such as trochlear lesions, age, and lesion size, using patient medical records.

RESULTS

A total of 125 patients were included in the study, with an average age of 58.3 ± 6.8 years (range: 43-74 years old); 95 (76%) were female and 30 (24%) were male. The average hip-knee-ankle (HKA) angle for measuring varus deformity was 7.6° ± 2.4° (range: 5.0-14.2°). In second-look arthroscopy, the status of medial femoral condyle (MFC) cartilage was as follows: 73 (58.4%) patients with ICRS grade I, 37 (29.6%) with ICRS grade II, and 15 (12%) with ICRS grade III. No patients were staged with ICRS grade IV. Additionally, the scores [except International Knee Documentation Committee (IKDC) at 1 year] of the ICRS grade I group improved more significantly than those of the ICRS grade II and III groups.

CONCLUSION

Implantation of hUCB-MSCs with concomitant HTO is an effective treatment for patients with medial compartment osteoarthritis and varus deformity. Regeneration of cartilage improves the clinical outcomes for the patients.

Preoperative Supine Radiographs Are More Accurate Than Standing Radiographs for Preoperative Planning in Medial Open-Wedge High Tibial Osteotomy

PURPOSE

To verify the accuracy of supine nonweight-bearing radiography versus standing radiography in preoperative planning and to determine the predictors of unintended limb alignment correction in medial open-wedge high tibial osteotomy (OWHTO).

METHODS

Consecutive patients who underwent medial OWHTO for medial osteoarthritis of the knee with varus alignment were retrospectively reviewed. The analyzed pre- and postoperative radiologic measurements included postoperative mechanical axis deviation (MAD) on standing whole-leg radiographs (WLRs), the predicted value of the postoperative MAD on the preoperative supine (predicted MAD_supine) radiograph, and standing WLRs (predicted MAD_stand). Multiple linear regression analysis was used to identify variables predicting the postoperative MAD and unintended MAD_stand correction, defined as the difference between predicted MAD_stand and postoperative MAD.

RESULTS

Predicted MAD_supine showed statistically greater reliability in predicting postoperative MAD than predicted MAD_stand (intraclass correlation coefficient, 0.82 vs 0.45). Postoperative MAD was correlated with the predicted MAD_supine and the difference in hip-knee-ankle angle between preoperative standing and supine WLRs (ΔHKA angle_stand-supine) (R =763, R² = 0.582, adjusted R² = 0.569, P < .001) and did not differ significantly from the predicted MAD_supine, with a mean difference of 0.28% ± 5.11% (P = .656). The mean unintended MAD_stand correction was 6.52% ± 8.66%. The difference in preoperative MAD between standing and supine WLRs was a significant predictor for unintended MAD_stand correction (β = -0.350, P = .004).

CONCLUSIONS

Preoperative planning with supine WLRs can predict postoperative limb alignment in medial OWHTO more accurately than standing radiographs. The clinical significance of the ΔHKA angle_stand-supine for the risk of overestimation of postoperative limb alignment might be low because of the low power in the prediction model and small value of the ΔHKA angle_stand-supine. Preoperative soft-tissue laxity was significantly correlated with unintended correction of postoperative limb alignment resulting from preoperative planning with standing radiographs.

LEVEL OF EVIDENCE

Level IV, retrospective comparative study.

Uniplane medial opening wedge high tibial osteotomy relative to a biplane osteotomy can reduce the incidence of lateral-hinge fracture

PURPOSE

With surgical modifications reflecting plate design differences of the specific rigid locking plate adding a metal wedge, uniplane high tibial osteotomy (HTO) has fewer lateral-hinge fractures and fewer plate irritations than biplane HTO.

METHODS

Uniplane HTO with a rigid locking plate adding a metal wedge was compared with biplane HTO with a rigid locking plate including a proximal D-hole. For comparison, the HTO patients' medical records and radiological results in a single institution were retrospectively reviewed. The Oxford knee score 2 years post-operation, CT scan at post-operative day 2 and serial standing long-bone scanography were reviewed to evaluate clinical outcome and radiological results, including the incidence of lateral-hinge fracture, plate irritation and correction loss to varus alignment.

RESULTS

A total of 103 knees, including 59 uniplane HTO and 44 biplane HTO, were enrolled. The Oxford scores were 38.1 ± 7.8 in the uniplane group and 35.9 ± 8.3 in the biplane group (ns). On CT scans, more lateral-hinge fractures developed in the biplane group, and seven knees (12%) of the uniplane group and 12 knees (27%) of the biplane group had Takeuchi type I stable hinge fracture (p < 0.05); unstable fracture was not noted in either group. Plate irritation occurred in nine knees (19%) of the uniplane group and in 14 knees (32%) of the biplane group, and the difference was statistically significant (p < 0.05).

CONCLUSION

In clinical situations including the use of surgical modifications reflecting plate design differences, fewer lateral-hinge fractures developed after uniplane medial opening-wedge HTO compared with biplane HTO. Uniplane HTO potentially represents a better option than biplane HTO for the prevention of lateral-hinge fracture.

LEVEL OF EVIDENCE

IV.

Preoperative latent medial laxity and correction angle are crucial factors for overcorrection in medial open-wedge high tibial osteotomy

PURPOSE

This study aimed to determine which preoperative factors affect the postoperative change in the joint line convergence angle (JLCA) by preoperatively quantifying soft tissue laxity.

METHODS

Thirty-four patients who underwent medial open-wedge high tibial osteotomy (HTO) with a navigation were analysed. The JLCA change after HTO was calculated using standing long-bone anteroposterior radiographs taken preoperatively and 6 months postoperatively. Latent soft tissue laxity was defined as the amount of soft tissue that can be extended to valgus or varus from the weight-bearing position, and calculated by subtracting the JLCA on weight-bearing standing radiographs from that on stress radiographs. Multiple linear regression was performed to determine the preoperative factors that statistically correlated with the postoperative JLCA change.

RESULTS

In multiple linear regression, JLCA change had a statistically significant correlation with latent medial laxity (R = 0.6) and a statistically borderline significant correlation with correction angle (R = 0.2). These imply that the postoperative JLCA change increased by 0.6° per 1° increase in latent medial laxity, and increased by 0.2° per 1° increase in correction angle. Latent medial laxity was the most crucial factor associated with postoperative JLCA changes.

CONCLUSION

The JLCA change could be larger in patients with large latent medial laxity or severe varus deformity requiring a large correction, which could lead to unexpected overcorrection in HTO. Postoperative JLCA change should be considered in preoperative surgical planning. Target point shifting within the hypomochlion point could be a strategy to prevent overcorrection, especially in patients with large latent medial laxity.

LEVEL OF EVIDENCE

Level IV.

Early experience of lateral hinge fracture during medial opening-wedge high tibial osteotomy: incidence and clinical outcomes

PURPOSE

Lateral hinge fracture (LHF) during a medial opening-wedge high tibial osteotomy (MOWHTO) is considered to be the main cause of instability, further displacement, loss of correction, malunion, and nonunion. The purposes of this study were to evaluate whether the incidence of LHFs during MOWHTOs has decreased as the number of cases performed over time has increased, and whether the radiographic and clinical outcomes of patients with LHFs were worse than those of patients without LHFs.

MATERIALS AND METHODS

During the period of July 2013 to January 2017, 132 MOWHTOs were performed by a single surgeon using a locking plate (TomoFix^®, DePuySynthes, Solothurn, Switzerland) for the treatment of medial compartment osteoarthritis, with LHFs postoperatively detected in 32 knees (24.2%). To evaluate trends in the incidence of LHFs occurring during MOWHTOs over time, all 132 cases were divided chronologically into four groups of 33 cases and compared. The time for bony union and loss of correction were compared between the LHF group and the non-LHF group using an osteotomy filling index, hip-knee-ankle (HKA) angles, medial proximal tibial angles (MPTA), weight-bearing line (WBL) ratios, and posterior tibial slope (PTS) angles on radiographs. Clinical outcomes were also compared using the Knee Society Scores (KSS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores 1 year post-surgery.

RESULTS

The incidence of LHFs in each group of 33 cases did not decrease over time (21.2%, 27.3%, 24.2%, and 24.2%, respectively, p = 0.954). The time to union was significantly different between the non-LHF group (5.0 months) and the LHF group (7.3 months) (p < 0.001). However, there were no immediate or 1-year postoperative differences in the HKA angles, MPTAs, WBL ratios, or PTS angles between the non-LHF and LHF groups (all p > 0.05). The KSS and WOMAC scores were significantly improved in both groups (all p < 0.001) 1 year post-surgery, without any differences between the groups (p = 0.997 and p = 0.122, respectively).

CONCLUSIONS

LHFs during MOWHTO procedures occurred consistently, with a similar incidence over time. Although patients with LHFs required more time to bony union, they showed similarly favorable radiographic and clinical results as the patients without LHFs 1 year after surgery.

What is the relationship between the "Fujisawa point" and postoperative knee valgus angle? A theoretical, computer-based study

BACKGROUND

The purpose of this study was to determine the relationship between the Fujisawa point and postoperative knee valgus angle and the anatomical factors influencing this relationship.

METHODS

An experimental study was conducted including 116 patients with medial compartment knee osteoarthritis undergoing treatment with open-wedge high tibial osteotomy (OWHTO). Each patient received simulated HTO through the Fujisawa point in the picture archiving and communication system (PACS). The preoperative hip-knee-ankle (HKA) angle and lower extremity anatomical parameters were recorded before the computerized HTO simulation. The postoperative knee valgus angle was measured after this procedure. A second simulation HTO was performed to adjust the mechanical axis to the optimal valgus angle (4.5°) and calculate the percentage of the tibial plateau width where the Mikulicz line crossed the knee. The Spearman correlation test and multivariate regression were used for analysis.

RESULTS

The median preoperative HKA varus angle of this study cohort was 174.1° (170.8, 176.2°). The median knee valgus angle after simulated osteotomy through the Fujisawa point was 2.4° (2.1, 2.7°). The valgus angle was positively correlated with the tibial plateau width (r = 0.23, p = .013) and preoperative HKA angle (r = 0.32, p < .001). Multivariate regression analysis showed that the preoperative HKA angle was a significant contributor to the postoperative valgus angle. When conducting the osteotomy with the optimal valgus angle (4.5°), the percentage of the Mikulicz line passing through the tibial plateau was 71.93% (67-78%).

CONCLUSIONS

The preoperative HKA angle affects the postoperative valgus angle after HTO. If the optimal valgus angle of 4.5° is desired, a more lateral position of the Fujisawa point should be targeted during OWHTO, which accounts for approximately 71.9% of the tibial plateau.

Difference between Mechanical Alignment in Navigation and Scanogram during Total Knee Arthroplasty

Introduction

Malpositioning of the implant results in polyethylene wear and loosing of implant after total knee arthroplasty. Scanogram is often used for measurement of limb alignment. Computer navigation provides real time measurements and thus, the aim is to see any association pre- and postoperatively between coronal alignments measured on scanogram to computer navigation during total knee arthroplasty.

Material and Methods

We prospectively gathered data of 200 patients with advanced degenerative symptomatic arthritis, who were consecutively selected for primary total knee arthroplasty with computer navigation. Every patient's pre- and postoperative scanogram were compared to the intraoperative computer navigation findings.

Results

The results show that the preoperative mean mechanical axis on navigation was 10.65° (SD ± 6.95) and on scanogram it was 10.38° (SD ± 6.89). On the other hand, the mean postoperative mechanical axis on navigation was 0.69° (SD ± 0.87) and on scanogram it was 2.73° (SD ± 2.10). Preoperatively, there was no significant difference (p value = 0.46) between the two. However, the postoperative outcomes suggest that there was a noteworthy difference, with no correlation between the mean Hip-Knee Ankle Axis (HKA) and intraoperative mechanical axis (p value <0.0001).

Conclusion

Postoperative mechanical alignment values after total knee arthroplasty are lower on navigation than measured on standing full length hip to ankle scanogram.

Clinical efficacy of preoperative 3D planning for reducing surgical errors during open-wedge high tibial osteotomy

Increases in posterior tibial slope (PTS) with open-wedge high tibial osteotomy (OWHTO) are often related to two surgical errors: Symmetric opening of the osteotomy gap and a tendency to open the gap from the anteromedial direction. The study objective was to define trends in these two errors using computer simulation and clinical effects of their countermeasures. First, 60 knees with varus deformity were assessed with three-dimensional (3D) planning using computed tomography to allow for the mechanical axis to pass through a point at 62.5% of the width of the tibial plateau, defined as the weight-bearing line percentage (WBL%). Anterior and posterior widths of the opening gap to maintain PTS were measured. The effect on PTS when osteotomy gaps were opened from the anteromedial direction up to 30° was evaluated. Mean anterior width (y) was 6.6 mm (range, 2.2-10.9) and mean posterior width (x) was 9.1 mm (range, 3.9-15.7), which can be expressed as y = 0.75x - 0.24. Opening gaps from the anteromedial direction at 10°, 20°, and 30° led to a mean PTS increase of 1.9°, 3.9°, and 5.6°, respectively. In most cases, WBL% with anteromedial opening at 30° passed through a point at less than 60%. In 47 knees that underwent OWHTO using 3D planning, postoperative coronal and sagittal bone corrections were mostly accurate. However, postoperative WBL% was negatively correlated with correction angle because of difficulties in predicting medial joint tightness. Preoperative 3D planning for OWHTO can reduce surgical errors, but postoperative WBL% remains variable. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

The Learning Curve for Biplane Medial Open Wedge High Tibial Osteotomy in 100 Consecutive Cases Assessed Using the Cumulative Summation Method

Purpose

The purpose of this study was to investigate whether surgical experience could improve surgical competency in medial open wedge high tibial osteotomy (MOWHTO).

Materials and Methods

One hundred consecutive cases of MOWHTO were performed with preoperative planning using the Miniaci method. Surgical errors were defined as under- or overcorrection, excessive posterior slope change, or the presence of a lateral hinge fracture. Each of these treatment failures was separately evaluated using the cumulative summation test for learning curve (LC-CUSUM).

Results

The LC-CUSUM showed competency in prevention of undercorrection, excessive posterior slope change, and lateral hinge fracture after 27, 47, and 42 procedures, respectively. However, the LC-CUSUM did not signal achievement of competency in prevention of overcorrection after 100 procedures. Furthermore, the failure rate for overcorrection showed an increasing tendency as surgical experience increased.

Conclusions

Surgical experience may improve the surgeon’s competency in prevention of undercorrection, excessive posterior slope change, and lateral hinge fracture. However, it may not help reduce the incidence of overcorrection even after performance of 100 cases of MOWHTO over a period of 6 years.

A Retrospective Comparison of Union Rates After Open Wedge High Tibial Osteotomies With and Without Synthetic Bone Grafts (Hydroxyapatite and β-tricalciumphosphate) at 2 Years

PURPOSE

To evaluate the clinical and radiological results of no bone graft (NBG) after opening wedge high tibial osteotomy (OWHTO) with a locking plate and to compare the bone union rate between the synthetic bone graft (SBG) group and the NBG group after OWHTO using serial radiographs.

METHODS

From 2012 to 2015, OWHTOs were performed with SBG or without bone graft using long locking plates. Inclusion criteria were: (1) OWHTO for disease of the medial compartment with varus deformity, and (2) minimum 2-year follow-up and radiographs taken serially to 2 years. Exclusion criteria were: (1) follow-up period <2 years (n = 8) or (2) absence of at least 1 radiograph taken at each follow-up point (n = 14). We retrospectively reviewed radiographs taken preoperatively and at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. Groups comprised those filled with a synthetic bone [hydroxyapatite (HA) and β-tricalciumphosphate (TCP), n=33, SBG group] or without a bone graft (n = 38, NBG group). We compared bone union rate between the 2 groups by measuring the union zone from zone 1 to zone 5 in serial radiographs using Fisher's exact test.

RESULTS

OWHTO was performed in a total of 93 knees and 71 knees were included in this study. Both groups showed good clinical and radiological results without correction loss at 2 years. The entire NBG group and 93.9% of the SBG group showed union over zone 3 at 2 years. However, the NBG group showed significantly more incorporation than the SBG group at 6 months (P = .006), 1 year (P = .0003), and 2 years (P = .0003).

CONCLUSIONS

Union without correction loss was obtained after OWHTO without bone graft. The NBG group showed significantly more incorporation than the SBG group (HA and β-TCP) within 2 years.

LEVEL OF EVIDENCE

Level IV, case series.

Are three-dimensional patient-specific cutting guides for open wedge high tibial osteotomy accurate? An in vitro study

Background

The aim of this in vitro study was to assess the accuracy of three-dimensional patient-specific cutting guides for open wedge high tibial osteotomy (OWHTO) to provide the planned correction in both frontal and sagittal planes.

Methods

Ten cadaveric tibias underwent OWHTO performed using a patient-specific cutting guide based on 3D preoperative planning. An initial CT scan of the tibias was performed, and after segmentation, 3D geometrical models of the pre-OWHTO tibias were obtained. Reference planes were defined, and OWHTO virtually planned to then design patient-specific cutting guides. OWHTO were performed using the patient-specific cutting guides. The patient-specific cutting guide controls the cut and the correction of the OWHTO in both planes. 3D models of post-OWHTO tibias were created after a postoperative CT scan. Geometrical post-OWHTO 3D models were superimposed on pre-OWHTO 3D models. Mechanical medial proximal tibial angle (mMPTA) in the frontal plane and posterior tibial slope (PTS) in the sagittal plane were compared between planned-OWHTO and post-OWHTO 3D reconstructions relative to the pre-OWHTO reference planes and axis. Pearson’s and Lin’s correlation tests were performed to assess precision and accuracy of patient-specific cutting guides.

Results

The mean difference between post-OWHTO and planned-OWHTO was 0.2° (max 0.5°, SD 0.3°) in the frontal plane and − 0.1° (max 0.8°, SD 0.5°) in the sagittal plane. Statistically significant correlations were found between the planned-OWHTO and post-OWHTO configurations for the mMPTA (p < 0.0001) and PTS (p < 0.0001) measurements, and the bias correction factor was 0.99 in both planes.

Conclusions

3D patient-specific cutting guides for OWHTO-based 3D virtual planning is a reliable and accurate method of achieving multiplanar correction in both frontal and sagittal planes.

Comparison of navigated and conventional high tibial osteotomy for the treatment of osteoarthritic knees with varus deformity: A meta-analysis

BACKGROUND

High tibial osteotomy (HTO) is a usefully surgical procedure to correct the malalignment and delay the progression of osteoarthritis. It is still controversy whether navigation system can offer more accuracy of targeted alignment and achieve better clinical outcomes than conventional method. The purpose of present meta-analysis was to investigate whether navigation system was superior to conventional method with regard to clinical and radiographic outcomes.

METHOD

The included studies compared the clinical and radiographic outcomes between navigated HTO group and conventional group. The clinical assessments were Lysholm Score, AKS Function Score and Arc of motion, and the radiographic outcomes were Mechanical axis (MA), Weight bearing line ratio (WBL), Outliers of alignment and Change in TPS used to evaluate alignment correction. The meta-analysis was performed using Review Manager 5.3 software. Downs and Black and the Newcastle-Ottawa Scale (NOS) were used to evaluate the study quality.

RESULT

Sixteen studies were eligible in present meta-analysis, including thirteen studies concerning opening wedge HTO and three studies involving closing wedge HTO. Clinical outcomes were only reported in studies which used opening wedge HTO. No significant differences were observed in all clinical outcomes between navigated and conventional HTO. Regarding radiographic outcomes, no significant difference in WBL ratio was observed between navigated and conventional HTO. Patients undergoing navigated HTO were associated with significantly greater in MA and lower in Outliers of alignment compared with those undergoing conventional HTO. Compared with conventional HTO, increase in TPS was significantly lower in navigated HTO group using opening wedge HTO, but decrease in TPS was significantly greater in navigated HTO group using closing wedge HTO.

CONCLUSION

Our meta-analysis demonstrated that navigated HTO offered more accuracy and precision of alignment correction, except WBL ratio. However, better clinical outcomes were not observed in navigation group.

Effect of Computer Navigation on Accuracy and Reliability of Limb Alignment Correction following Open-Wedge High Tibial Osteotomy: A Meta-Analysis

Background

It is unclear whether computer navigation can improve the accuracy and reliability of targeted lower limb alignment correction following open-wedge high tibial osteotomy (HTO). This meta-analysis was designed to compare the accuracy and reliability of limb alignment correction between computer navigated and conventional open-wedge HTOs.

Methods

Studies that compared postoperative coronal alignment, including mechanical axis (MA) and weight bearing line (WBL) ratio, outliers of alignment correction, and change in tibial posterior slope, following open-wedge HTO performed using computer navigated and conventional methods were included.

Results

Ten studies were included in the meta-analysis. The MA (0.93°; 95% confidence interval [CI]: 0.45–1.41°; P < 0.001) and WBL ratio (1.5%; 95% CI: 0.03–2.98%; P = 0.048) were significantly greater for computer navigated HTO than for conventional HTO. Outliers of alignment correction after surgery were significantly lower in patients who underwent computer navigated HTO than in those who underwent conventional HTO (odds ratio: 0.25; 95% CI: 0.08–0.79; P = 0.02). Changes in posterior tibial slope from before to after surgery, however, were similar for the two approaches.

Conclusion

Computer navigated HTO resulted in slightly more valgus postoperative alignment and effectively reduced outliers of alignment correction but had no effect on change in posterior tibial slope when compared with conventional HTO.

Factors affecting articular cartilage repair after open-wedge high tibial osteotomy

BACKGROUND

To evaluate the factors that affect articular cartilage repair after open-wedge high tibial osteotomy (OWHTO) and the relationship between regeneration of articular cartilage repair and clinical outcomes.

METHODS

Among the cases of OWHTO that were performed from March 2005 to February 2012, the patients who followed up for >2years and received a second-look arthroscopy were retrospectively reviewed. For clinical evaluation, the Knee Society scores and Western Ontario and McMaster Universities Osteoarthritis Index score were measured. For radiologic evaluation, the Kellgren-Lawrence scale, mechanical femorotibial angle, and joint line obliquity were used. In the initial and second-look arthroscopy, the status of the articular cartilage of the medial compartment was evaluated.

RESULTS

A total of 62 knees (61 patients) were included in this study. Articular cartilage repair was observed in 18 knees (29.0%). In multiple logistic regression analysis, patients with Kellgren-Lawrence Grade 4 (OR 0.076; 95% CI 0.007-0.822; P=0.034), the existence of a bipolar lesion (OR 0.108; 95% CI 0.016-0.724; P=0.022), or joint line obliquity >5° (OR 0.109; 95% CI 0.013-0.936; P=0.043) had significantly lower odds of articular cartilage repair compared to the corresponding counter group. In a comparison of clinical outcomes between a group that had articular cartilage repair and a group without repair, no significant difference was observed (P>0.05).

CONCLUSIONS

Severe arthrosis, existence of a bipolar lesion, and marked postoperative joint line obliquity had a negative impact on articular cartilage repair after OWHTO. However, articular cartilage repair showed unknown clinical significance.

Factors associated with discrepancies between preoperatively planned and postoperative alignments in patients undergoing closed-wedge high tibial osteotomy

BACKGROUND

To evaluate the difference between preoperative plan and postoperative alignment after closed-wedge HTO and determine factors associated with difference.

METHODS

This retrospective cohort study included 165 cases with closed-wedge HTO. The following radiographic parameters were measured: mechanical tibiofemoral angle (mTFA), mechanical medial proximal tibial angle (MPTA), joint line convergence angle, mediolateral joint width discrepancy, Kellgren-Lawrence (K-L) grade, and discrepancy between the correction angle in tibia and correction angle in mTFA. The linear regression analysis was used for the preoperative factors that affect the discrepancy between correction angle in tibia and correction angle in mTFA.

RESULTS

Preoperative and postoperative mTFA was varus 8.3°±3.7 and valgus 3.1°±2.6. The MPTA was varus 6.2°±3.1 preoperatively, valgus 3.7°±3.0 postoperatively. The mediolateral joint width discrepancy was 3.1mm±1.8 preoperatively and 1.8mm±1.4 postoperatively. The discrepancy between correction angle in tibia and correction angle in mTFA was 1.5°±2.3 valgus. By regression analysis, one degree of valgus overcorrection was found to be related with every 2.5° of joint convergence angle (r²=0.396), 2.4mm of mediolateral joint width discrepancy (r²=0.310) and increased one grade of K-L classification (r²=0.107) as preoperative measurement.

CONCLUSIONS

The 1.5° valgus overcorrection of postoperative mTFA was found compared with planned correction angle in tibia. By the equation, every 2.5° of joint convergence angle and 2.4mm of mediolateral joint width discrepancy preoperatively could predict one degree of valgus overcorrection.

Intraoperative adjustment of alignment under valgus stress reduces outliers in patients undergoing medial opening-wedge high tibial osteotomy

INTRODUCTION

A considerable percentage of outliers with under- or over-correction continue to be reported despite precise preoperative planning and cautious intraoperative correction of lower limb alignment in medial opening-wedge high tibial osteotomy (MOWHTO). The purpose of this study was to determine whether our novel technique for the intraoperative adjustment of alignment under valgus stress reduces the number of outliers in patients undergoing MOWHTO compared to the conventional technique, which corrects alignment according to the cable method only.

MATERIALS AND METHODS

One hundred seventeen consecutive knees were enrolled in this case-control study. The first 52 knees (51 patients) were corrected in accordance with preoperative plans using the Dugdale method with modification with an intraoperative cable (group 1). In the other 65 knees (60 patients), the angle was corrected using the Dugdale method and limb alignment was adjusted using the intraoperative cable technique by applying valgus stress to the knee joint (group 2). The postoperative weight bearing line ratios and mechanical axis of the lower limb were compared at postoperative one year. Each knee was evaluated according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score preoperatively and at postoperative one year.

RESULTS

A significant reduction in the number of outliers was seen in group 2 compared to group 1 (group 1 = 48.1%, group 2 = 9.2%, p < 0.001). Nineteen of 52 knees (36.5%) were under-corrected in group 1, whereas 6 of 65 knees (9.2%) were under-corrected in group 2 (p < 0.001). Six of 52 knees (11.6%) were over-corrected in group 1, whereas 0 of 65 knees (0.0%) were over-corrected in group 2 (p = 0.005). At one -year after operation, group 2 showed significantly lower WOMAC score than group 1 (p = 0.014).

CONCLUSIONS

Intraoperative adjustment of alignment under valgus stress significantly reduced the number of outliers compared to a technique that corrected alignment using the cable method in patients undergoing MOWHTO.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Collagen Augmentation Improves the Quality of Cartilage Repair After Microfracture in Patients Undergoing High Tibial Osteotomy: A Randomized Controlled Trial

BACKGROUND

The quality of cartilage repair after marrow stimulation is unpredictable. To overcome the shortcomings of the microfracture technique, various augmentation techniques have been developed. However, their efficacies remain unclear.

HYPOTHESIS

The quality of cartilage repair and clinical outcomes would be superior in patients undergoing high tibial osteotomy (HTO) with microfracture and collagen augmentation compared to those undergoing HTO with microfracture alone without collagen augmentation for the treatment of medial compartment osteoarthritis (OA) of the knee.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Twenty-eight patients undergoing HTO were randomized into 2 groups: microfracture alone (group 1, n = 14) or microfracture with collagen augmentation (group 2, n = 14). At 1 year postoperatively, second-look arthroscopic surgery and biopsy of repaired cartilage were performed at the time of HTO plate removal. Biopsy specimens were graded using the International Cartilage Repair Society Visual Assessment Scale II (ICRS II). In addition, imaging outcomes in terms of the magnetic resonance observation of cartilage repair tissue (MOCART) score were assessed based on magnetic resonance imaging (MRI). Finally, clinical outcomes in terms of the visual analog scale (VAS) for pain score, Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, and Tegner activity scale score were evaluated.

RESULTS

The mean ICRS II score in group 2 was significantly higher than that in group 1 (1053.2 vs 885.4, respectively; P = .002). Group 2 showed greater improvement in tissue morphology, cell morphology, surface architecture, middle/deep zone assessment, and overall assessment compared with group 1 ( P < .050 for all comparisons). Imaging outcomes based on the MOCART score were superior in group 2 compared to those in group 1 on MRI at 1 year postoperatively (64.6 vs 45.4, respectively; P = .001). The degree of defect repair was better in group 2 than in group 1 ( P = .040). Clinical outcomes in terms of the VAS for pain score, KOOS, IKDC score, and Tegner activity scale score were improved in both groups without between-group differences ( P > .100 for all comparisons).

CONCLUSION

The quality of cartilage repair after microfracture with collagen augmentation was superior to that after microfracture alone in patients undergoing HTO. Clinical results after 1 year did not reflect this difference in tissue repair. Therefore, a longer follow-up of the cohort is needed to answer this question.

Intraoperative Fluoroscopic Assessment of Limb Alignment is a Reliable Predictor for Postoperative Limb Alignment in Biplanar Medial Opening-Wedge High Tibial Osteotomy

BACKGROUND

The purpose of this study was to assess the reliability of pre-, intra operative, and postoperative limb alignment measurements and investigate the correlation between the measurements in biplanar medial opening-wedge high tibial osteotomy.

METHODS

This study enrolled 59 knees undergoing biplanar opening-wedge high tibial osteotomy for primary medial osteoarthritis with varus deformity. Preoperative and postoperative standing lower leg radiographs and intraoperative fluoroscopic images were taken. Two independent examiners analyzed the radiologic data to assess lower limb alignment and mechanical axis (MA) deviation (percentage of MA position on tibial plateau). The effect of preoperative hip-knee-ankle angle and MA deviation, age, sex, body mass index (BMI), and joint line convergence angle on the discrepancy between intraoperative and postoperative MA deviation was analyzed.

RESULTS

The mean preoperative hip-knee-ankle angle and MA deviation were varus 7.7 ± 3.3° and 14.1 ± 15.1%, respectively. After osteotomy, the mean intraoperative postosteotomy MA deviation was 57.9 ± 2.1% in supine position, and the mean post-operative MA deviation increased to 63.9 ± 2.9% on standing radiographs. The mean difference between intraoperative postosteotomy MA deviation and postoperative MA deviation was 6.1 ± 2.2%. Linear regression analysis between intraoperative postosteotomy MA deviation and postoperative MA deviation showed a statistically significant linear relationship (R² = 0.449; P < .001). Multivariate regression analysis revealed that preoperative joint line convergence angle (β = 0.856; P < .001) and BMI (β = 0.349; P < .001) were significant positive predictors for the difference in MA deviation.

CONCLUSION

There was a significant linear relationship between intraoperative postosteotomy MA deviation and postoperative MA deviation following biplanar medial opening-wedge high tibial osteotomy. A greater discrepancy between MA deviations was significantly associated with higher BMI and joint line convergence angle.

Effect of soft tissue laxity of the knee joint on limb alignment correction in open-wedge high tibial osteotomy

PURPOSE

Open-wedge high tibial osteotomy (HTO) cannot always accurately correct limb alignment, resulting in under- or over-correction. This study assessed the relationship between soft tissue laxity of the knee joint and alignment correction in open-wedge HTO.

METHODS

This prospective study involved 85 patients (86 knees) undergoing open-wedge HTO for primary medial osteoarthritis. The mechanical axis (MA), weight-bearing line (WBL) ratio, and joint line convergence angle (JLCA) were measured on radiographs preoperatively and after 6 months, and the differences between the pre- and post-surgery values were calculated. Post-operative WBL ratios of 57-67 % were classified as acceptable correction. WBL ratios <57 and >67 % were classified as under- and over-corrections, respectively.

RESULTS

Preoperative JLCA correlated positively with differences in MA (r = 0.358, P = 0.001) and WBL ratio (P = 0.003). Difference in JLCA showed a stronger correlation than preoperative JLCA with differences in MA (P < 0.001) and WBL ratio (P < 0.001). Difference in JLCA was the only predictor of both difference in MA (P < 0.001) and difference in WBL ratio (P < 0.001). The difference between pre- and post-operative JLCA differed significantly between the under-correction, acceptable-correction, and over-correction groups (P = 0.033). Preoperative JLCA, however, did not differ significantly between the three groups. Neither preoperative JLCA nor difference in JLCA correlated with change in posterior slope.

CONCLUSIONS

Preoperative degree of soft tissue laxity in the knee joint was related to the degree of alignment correction, but not to alignment correction error, in open-wedge HTO. Change in soft tissue laxity around the knee from before to after open-wedge HTO correlated with both correction amount and correction error. Therefore, a too large change in JLCA from before to after open-wedge osteotomy may be due to an overly large reduction in JLCA following osteotomy, suggesting alignment over-correction during surgery.

LEVEL OF EVIDENCE

II.

How accurately does high tibial osteotomy correct the mechanical axis of an arthritic varus knee? A systematic review

BACKGROUND

The aim of this study was to give an overview of the accuracy of coronal limb alignment correction after high tibial osteotomy (HTO) for the arthritic varus knee by performing a systematic review of the literature.

METHODS

The databases PubMed, MEDLINE and Cochrane Library were screened for relevant articles. Only prospective clinical studies with the accuracy of alignment correction by performing HTO as primary or secondary objective were included.

RESULTS

Fifteen studies were included in this systematic review and were subdivided in 23 cohorts. A total of 966 procedures were considered. Nine cohorts used computer navigation during HTO and the other 14 cohorts used a conventional method. In seven computer navigation cohorts, at least 75% of the study population fell into the accepted "range of accuracy" (AR) as proposed by the different studies, but only six out of 14 conventional cohorts reached this percentage. Four out of eight conventional cohorts that provided data on under- and overcorrection, had a tendency to undercorrection.

CONCLUSIONS

The accuracy of coronal alignment corrections using conventional HTO falls short. The number of procedures outside the proposed AR is surprising and exposes a critical concern for modern HTO. Computer navigation might improve the accuracy of correction, but its use is not widespread among orthopedic surgeons. Although HTO procedures have been shown to be successful in the treatment of unicompartmental knee arthritis when performed accurately, the results of this review stress the importance of ongoing efforts in order to improve correction accuracy in modern HTO.

Change in Posterior Tibial Slope After Open-Wedge and Closed-Wedge High Tibial Osteotomy: A Meta-analysis

BACKGROUND

It is unclear whether open- or closed-wedge high tibial osteotomy (HTO) results in significant changes in posterior tibial slope, with no consensus on the magnitude of such changes. Furthermore, methods of measuring posterior tibial slope differ among studies. This meta-analysis was therefore designed to evaluate whether posterior tibial slope increases after open-wedge HTO and decreases after closed-wedge HTO and to quantify the magnitudes of the slope changes after open- and closed-wedge HTO using various methods of measuring posterior tibial slope.

HYPOTHESIS

Posterior tibial slope increases after open-wedge and decreases after closed-wedge HTO. The magnitude of change is similar for the 2 methods, and the value obtained for posterior tibial slope change is affected by the method of measurement.

STUDY DESIGN

Meta-analysis.

METHODS

Multiple comprehensive databases, including MEDLINE, EMBASE, the Cochrane Library, and KoreaMed, were searched for studies that evaluated the posterior slope of the proximal tibia in patients who had undergone open- and/or closed-wedge HTO. Studies were included that compared pre- and postoperative posterior tibial slopes, regardless of measurement method, including anterior and posterior tibial cortex or tibial shaft axis as a reference line, in patients who underwent open- or closed-wedge HTO. The quality of each included study was appraised with the Newcastle-Ottawa Scale.

RESULTS

Twenty-seven studies were included in the meta-analysis. Pooled data, which included subgroups of 3 methods, showed that posterior tibial slope increased 2.02° (95% CI, 2.66° to 1.38°; P = .005) after open-wedge HTO and decreased 2.35° (95% CI, 1.38° to 3.32°; P < .001) after closed-wedge HTO.

CONCLUSION

This meta-analysis confirmed that posterior tibial slope increased after open-wedge HTO and decreased after closed-wedge HTO when the results of a variety of measurement methods were pooled. The magnitude of change after open- and closed-wedge HTO was similar and small (approximately 2°), suggesting that both osteotomy techniques may have little effect on the biomechanics of the cruciate ligaments.

Outcome reporting following navigated high tibial osteotomy of the knee: a systematic review

PURPOSE

This systematic review evaluates radiographic and clinical outcome reporting following navigated high tibial osteotomy (HTO). Conventional HTO was used as a control to compare outcomes and furthermore investigate the quality of evidence in studies reporting outcomes for navigated HTO. It was hypothesized that navigated HTO will show superior clinical and radiographic outcomes compared to conventional HTO.

METHODS

Two independent reviewers searched PubMed, Ovid (MEDLINE), EMBASE, and Cochrane databases for studies reporting outcomes following navigated HTO. Titles, abstracts, and full-text were screened in duplicate using an a priori inclusion and exclusion criteria. Descriptive statistics were calculated using Minitab ^® statistical software. Methodological Index for Nonrandomized Studies (MINORS) and Cochrane Risk of Bias Scores were used to evaluate methodological quality.

RESULTS

Thirty-four studies which involved 2216 HTOs were analysed in this review, 1608 (72.6 %) navigated HTOs and 608 (27.4 %) conventional HTOs. The majority of studies were of level IV evidence (16). Clinical outcomes were reported in knee and function scores or range of motion comparisons. Postoperative clinical and functional scores were improved by navigated HTO although it is not demonstrated if there is significant improvement compared to conventional HTO. Most common clinical outcome score reported was Lysholm scores (6) which report postoperative scores of 87.8 (standard deviation 5.9) and 88.8 (standard deviation 5.9) for conventional and navigation-assisted HTO, respectively. Radiographic outcomes reported commonly were weight-bearing mechanical axis, coronal plane angle, and posterior tibial slope angle in the sagittal plane. Studies have shown HTO gives significant correction of mechanical alignment and navigated HTO produces significantly less change in posterior tibial slope postoperatively compared to conventional. The mean MINORS for the 17 non-comparative studies was 9/16, and 15/24 for the 14 non-randomized comparative studies.

CONCLUSION

Navigation HTO results in improved mechanical axis alignment and demonstrates significantly better control over the tibial slope angle change postoperatively compared to conventional methods; however, these improvements have not yet been reflected in clinical outcome scores. Overall the studies report HTO does create significantly improved knee scores and functions compared to patients' preoperative ratings regardless of technique. Future studies on HTO outcomes need to focus on consistency of outcome reporting.

LEVEL OF EVIDENCE

IV.

Ability of an intentionally smaller anterior than posterior gap to reduce the sagittal tibial slope in opening wedge high tibial osteotomy

Background

We utilized in vivo 3- dimensional (D) computed tomography (CT) to determine whether the preoperatively planned anterior and posterior opening gap heights correlated with the real gaps following opening wedge high tibial osteotomy (HTO), as well as the relationships between anterior and posterior gap heights and change in sagittal tibial slope.

Methods

This prospective study involved 41 patients (41 knees) undergoing navigation HTO for primary medial osteoarthritis. Mechanical axis (MA), weight-bearing line (WBL) ratio, and posterior tibial slope were measured on radiographs preoperatively and after 3 months. The anterior and posterior opening gaps created by osteotomy were measured using in vivo 3D CT and the patients were classified into a larger anterior or posterior gap group.

Results

Of the 41 patients, 24 (59 %) had larger anterior and 17 (41 %) had larger posterior gaps. There were no between group differences in preoperative and postoperative slopes, or in change in slope. The correlation between preoperatively planned and postoperative posterior gaps was good, whereas the correlation of anterior gaps was only fair. Bland-Altman plots showed poor agreement for both preoperative and postoperative anterior and posterior gaps. The mean systematic difference (bias) was 2.3 mm (p < 0.001) for anterior and -1.0 mm (p = 0.033) for posterior gaps.

Conclusions

Preoperatively calculated opening gaps, which were planned to be larger posteriorly than anteriorly to minimize the change in slope after surgery, did not correspond with postoperative opening gaps on 3D CT. In addition, postoperative tibial slope did not increase, even when the anterior gap was larger than the posterior gap.

Trial registration

Trial registration number: KCT0001905, April 29, 2016.

Does Superficial Medial Collateral Ligament Release in Open-Wedge High Tibial Osteotomy for Varus Osteoarthritic Knees Increase Valgus Laxity?

BACKGROUND

Medial open-wedge high tibial osteotomy (OWHTO) requires the release of the superficial medial collateral ligament (sMCL). However, research on medial laxity among patients who undergo OWHTO is rare.

PURPOSE

To evaluate the changes in medial laxity of the knee joint as related to the complete release of the sMCL through serial valgus stress radiographs in patients who underwent OWHTO.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 48 patients (54 knees) who received OWHTO and were followed for more than a year and for whom serial valgus stress radiography data were available were retrospectively reviewed. To assess the medial laxity of knee joint, medial joint space opening (MJO) was measured while valgus stress of 15 kgf was loaded on the knee joint. The MJO was measured before surgery, during surgery before release of the sMCL under anesthesia, after the release, and after fixing with a TomoFix plate following the opening of the osteotomy site, as well as 3, 6, and 12 months after surgery. Serially measured MJOs were analyzed to evaluate the changes of medial laxity.

RESULTS

The MJO significantly increased after the release of the sMCL (mean ± SD, 12.2 ± 1.2 mm) compared with before the release (9.0 ± 1.1 mm) (P < .001). The MJO measured after fixing with the TomoFix plate following the opening of the osteotomy site (9.2 ± 1.2 mm) was significantly decreased compared with that measured after the release of the sMCL and was not significantly different from the MJO measured before release of the sMCL. No significant difference was observed among MJOs that were measured 3, 6, and 12 months after surgery. Comparison of MJOs before and after surgery also showed no significant differences.

CONCLUSION

Complete release of the sMCL during OWHTO increases the MJO. However, the MJO decreased to the level before sMCL release after fixing with the TomoFix plate following the opening of the osteotomy site. Medial laxity induced by the complete release of the sMCL can be recovered by opening the osteotomy site.

Reliability of the imaging software in the preoperative planning of the open-wedge high tibial osteotomy

PURPOSE

The purpose of this study was to verify a recently developed picture-archiving and communications system-photoshop method by comparing reliabilities between real-size paper template and the PACS-photoshop methods in preoperative planning of open-wedge high tibial osteotomy.

METHODS

A prospective case series was conducted, including patients with medial osteoarthritis undergoing open-wedge high tibial osteotomy. In the preoperative planning, the picture-archiving and communications system-photoshop method and real-size paper template method were used simultaneously in all patients. Preoperative hip-knee-ankle angle, height, and angle of the osteotomy were evaluated. The reliability of this newly devised method was evaluated, and the consistency between the two methods was also evaluated using intra-class correlation coefficient.

RESULTS

Using the picture-archiving and communications system-photoshop method, the mean correction angle and height of osteotomy gap of rater-1 were 11.7° ± 3.6° and 10.7 ± 3.6 mm, respectively. The mean correction angle and height of osteotomy gap of rater-2 were 12.0 ± 2.6 and 10.8 ± 3.6, respectively. The inter- and intra-rater reliabilities of the correction angle were 0.956 ~ 0.979 and 0.980 ~ 0.992, respectively. The inter- and intra-rater reliabilities of the height of the osteotomy gap were 0.968 ~ 0.985 and 0.971 ~ 0.994, respectively (p < 0.001). Using the real-size paper template method, the correction angle and height of the osteotomy gap were 11.5° ± 3.4° and 10.9 ± 3.8 mm, respectively. Using the picture-archiving and communications system-photoshop method, mean values of the correction angle and height of the osteotomy gap were 11.9° ± 3.6° and 10.8 ± 3.6 mm, respectively. Consistency between the two methods by comparing the means of the correction angle and the height of the osteotomy gap were 0.985 and 0.985, respectively (p < 0.001).

CONCLUSIONS

Use of the picture-archiving and communications system-photoshop method enables direct measurement of the height of the osteotomy gap with high reliability.