Difference of preoperative varus-valgus stress radiograph is effective for the correction accuracy in the preoperative planning during open-wedge high tibial osteotomy

The influence of the weight-bearing state on three-dimensional (3D) planning in lower extremity realignment - analysis of novel vs. state-of-the-art planning approaches

BACKGROUND

The use of 3D planning to guide corrective osteotomies of the lower extremity is increasing in clinical practice. The use of computer-tomography (CT) data acquired in supine position neglects the weight-bearing (WB) state and the gold standard in 3D planning involves the manual adaption of the surgical plan after considering the WB state in long-leg radiographs (LLR). However, this process is subjective and dependent on the surgeons experience. A more standardized and automated method could reduce variability and decrease costs.

PURPOSE

The aim of the study was (1) to compare three different three-dimensional (3D) planning modalities for medial open-wedge high tibial osteotomy (MOWHTO) and (2) to describe the current practice of adapting NWB CT data after considering the WB state in LLR. The purpose of this study is to validate a new, standardized approach to include the WB state into the 3D planning and to compare this method against the current gold standard of 3D planning. Our hypothesis is that the correction is comparable to the gold standard, but shows less variability due compared to the more subjective hybrid approach.

METHODS

Three surgical planning modalities were retrospectively analyzed in 43 legs scheduled for MOWHTO between 2015 and 2019. The planning modalities included: (1) 3D hybrid (3D non-weight-bearing (NWB) CT models after manual adaption of the opening angle considering the WB state in LLR, (2) 3D NWB (3D NWB CT models) and (3) 3D WB (2D/3D registration of 3D NWB CT models onto LLR to simulate the WB state). The pre- and postoperative hip-knee-ankle angle (HKA) and the planned opening angle (°) were assessed and differences among modalities reported. The relationship between the reported differences and BMI, preoperative HKA (LLR), medial meniscus extrusion, Outerbridge osteoarthritis grade and joint line convergence angle (JLCA) was analyzed.

RESULTS

The mean (std) planned opening angle of 3D hybrid did not differ between 3D hybrid and 3D WB (0.4 ± 2.1°) (n.s.) but was higher in 3D hybrid compared to 3D NWB (1.1° ± 1.1°) (p = 0.039). 3D WB demonstrated increased preoperative varus deformity compared to 3D NWB: 6.7 ± 3.8° vs. 5.6 ± 2.7° (p = 0.029). Patients with an increased varus deformity in 3D WB compared to 3D NWB (> 2 °) demonstrated more extensive varus alignment in LLR (p = 0.009) and a higher JLCA (p = 0.013).

CONCLUSION

Small intermodal differences between the current practice of the reported 3D hybrid planning modality and a 3D WB approach using a 2D/3D registration algorithm were reported. In contrast, neglecting the WB state underestimates preoperative varus deformity and results in a smaller planned opening angle. This leads to potential under correction in MOWHTO, especially in patients with extensive varus deformities or JLCA.

CLINICAL RELEVANCE

Incorporating the WB state in 3D planning modalities has the potential to increase accuracy and lead to a more consistent and reliable planning in MOWHTO. The inclusion of the WB state in automatized surgical planning algorithms has the potential to reduce costs and time in the future.

Relationship between increased knee joint line obliquity after medial open-wedge high tibial osteotomy and patient-reported outcome measures

INTRODUCTION

This study evaluated the correlation between postoperative knee joint line obliquity after medial open-wedge high tibial osteotomy and patient-reported outcome measures excluding excessively overcorrected knees. This study further identified preoperative radiological factors related to the increased postoperative knee joint line obliquity.

MATERIALS AND METHODS

We retrospectively evaluated patients who underwent medial open-wedge high tibial osteotomy between March 2013 and March 2021. Postoperative excessively overcorrected knees with hip-knee-ankle angle > 7° were excluded. We investigated radiological parameters and patient-reported outcome measures preoperatively and at the last follow-up. The following radiologic parameters were measured: hip-knee-ankle angle, weight-bearing line ratio, mechanical medial proximal tibial angle, mechanical lateral distal femoral angle, lateral distal tibial angle, joint line convergent angle, knee joint line obliquity, ankle joint line obliquity, hip abduction angle, tibial posterior slope, Carton-Deschamps index, and patella tilting angle. Clinical outcomes were evaluated using Japanese knee outcome measures. This assessment criterion is based on the Western Ontario McMaster Universities Arthritis Index and MOS Short Form 36. Multiple regression analysis was performed to evaluate the association between postoperative knee joint line obliquity and patient-reported outcome measures or preoperative radiological factors (P < .05).

RESULTS

A total of 52 knees were included. The mean age at the time of the surgery was 61.6 ± 9.0 years and the mean follow-up period was 30.6 ± 10.1 months. Increased postoperative knee joint line obliquity was associated with lower Japanese knee outcome measures. The preoperative hip-knee-ankle angle was significantly associated with postoperative knee joint line obliquity.

CONCLUSIONS

Increased knee joint line obliquity after medial open-wedge high tibial osteotomy is associated with inferior clinical outcomes. Care should be given to the center of the rotational angulation in around-knee osteotomy to avoid postoperative increased knee joint line obliquity.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Intraoperative Angle Measurement of Anatomical Structures: A Systematic Review

Ensuring precise angle measurement during surgical correction of orientation-related deformities is crucial for optimal postoperative outcomes, yet there is a lack of an ideal commercial solution. Current measurement sensors and instrumentation have limitations that make their use context-specific, demanding a methodical evaluation of the field. A systematic review was carried out in March 2023. Studies reporting technologies and validation methods for intraoperative angular measurement of anatomical structures were analyzed. A total of 32 studies were included, 17 focused on image-based technologies (6 fluoroscopy, 4 camera-based tracking, and 7 CT-based), while 15 explored non-image-based technologies (6 manual instruments and 9 inertial sensor-based instruments). Image-based technologies offer better accuracy and 3D capabilities but pose challenges like additional equipment, increased radiation exposure, time, and cost. Non-image-based technologies are cost-effective but may be influenced by the surgeon's perception and require careful calibration. Nevertheless, the choice of the proper technology should take into consideration the influence of the expected error in the surgery, surgery type, and radiation dose limit. This comprehensive review serves as a valuable guide for surgeons seeking precise angle measurements intraoperatively. It not only explores the performance and application of existing technologies but also aids in the future development of innovative solutions.

Small medial proximal tibial angle is a radiographic finding strongly associated with less coronal alignment correction under valgus stress in medial knee osteoarthritis

PURPOSE

The degree to which varus knees can be corrected manually is important when considering total versus unicompartmental knee arthroplasty (UKA). The primary aim was to clarify the relationship between the degree of coronal alignment correction and radiographic parameters involved in UKA prognosis using preoperative full-length lower extremity valgus stress radiography. The secondary aim was to identify the factors affecting alignment correction.

METHODS

This retrospective observational study included 115 knees with medial osteoarthritis that underwent knee osteotomy or arthroplasty. Percent mechanical axis without valgus stress (%MA: neutral, 50%; varus, <50% and valgus, >50%), mechanical lateral distal femoral angle, lateral bowing femoral angle, medial proximal tibial angle (MPTA), joint line convergence angle, medial and lateral joint space width (LJSW) and medial femoral and tibial joint osteophyte size were measured using preoperative full-length weight-bearing radiographs. Correlation and multiple linear regression analyses were used to assess associations between parameters and %MA with valgus stress or amount of %MA change (%MA with valgus stress minus %MA without valgus stress).

RESULTS

%MA with valgus stress was correlated with all radiographic parameters. %MA change was correlated with parameters except for MPTA and LJSW. Multiple regression analyses showed that %MA without valgus stress and MPTA were associated with both %MA with valgus stress and %MA change. When %MA with valgus stress was set at 30%, 40% and 50%, MPTA cutoff values were 81.6°, 83.5° and 84.9°, and cutoffs for %MA without valgus stress were 10.7%, 17.1% and 25.1%, respectively.

CONCLUSION

Small MPTA is strongly associated with less alignment correction under valgus stress in varus knees. The finding is useful in surgical planning, especially to avoid undercorrection with UKA when valgus stress radiographs are unavailable.

LEVEL OF EVIDENCE

Level III.

Intraoperative femurofibular angle combined with tibiofibular angle measurement has fewer correction errors in open-wedge high tibial osteotomy

AIM

This study aimed to verify the accuracy of intraoperative femurofibular angle combined with tibiofibular angle (FFA-TFA) measurement and compare it with traditional alignment line methods in open-wedge high tibial osteotomy (OWHTO).

METHODS

A total of 174 knees of 122 patients undergoing OWHTO and using an alignment line or FFA-TFA measurement as an index of optimal correction were included in this retrospective study. The intraoperative alignment line passed through the targeted weight-bearing line (WBL) of the tibial plateau in the alignment line group. The intraoperative FFA-TFA aligned to the preplanned FFA-TFA angle in the FFA-TFA group. WBL, FFA, TFA, and knee joint-line convergence angle of the femur and tibia were assessed as radiological results preoperatively and one year after surgery. The Knee Society Score and the Western Ontario and McMaster Universities were assessed as objective clinical results.

RESULTS

Postoperative WBL in the FFA-TFA group was closer to the target WBL than in the alignment line group (FFA-TFA vs alignment line group: 1.43 ± 1.20% vs 3.82 ± 3.29%; P < 0.001). The FFA-TFA group had fewer over-correction and under-correction rates than the alignment line group (28.7% and 12.6% vs 11.5% and 3.40%; P < 0.001). No significant differences were observed in the clinical results between the two groups one year after surgery (P > 0.05).

CONCLUSIONS

The intraoperative measurement of FFA-TFA had fewer complications in terms of under-correction and over-correction compared with the alignment line measurement. No significant differences between the two methods were observed in clinical results one year after surgery.

Constitutional and postoperative joint line obliquity can predict serial alignment change after opening-wedge high tibial osteotomy: analysis using coronal plane alignment of the knee classification

PURPOSE

The purposes of this study were (1) to clarify the distribution of the Coronal Plane Alignment of the Knee (CPAK) phenotype in patients who underwent medial opening-wedge high tibial osteotomy (OWHTO) and (2) to identify the predictive factors for postoperative serial alignment changes after OWHTO by analyzing constitutional phenotypes.

METHODS

Patients who underwent OWHTO between March 2014 and December 2019 were retrospectively evaluated. Those who completed a minimum follow-up of 3 years were divided into three groups based on the direction of alignment changes from postoperative 3 months to the final follow-up: Group 1 (varus direction) when the weight-bearing line ratio (WBLR) change was less than - 4%, Group 2 (maintained) when the WBLR change was between - 4% and 4%, and Group 3 (valgus direction) when the WBLR change was greater than 4%. The following parameters were assessed serially and compared between the groups: (1) radiologic parameters of coronal limb alignment such as joint line obliquity (JLO), (2) CPAK phenotypes, and (3) clinical outcomes.

RESULTS

In total, 163 knees were included, and the average duration of follow-up was 4.8 ± 1.6 years. More apex distal JLO was observed in the order of Group 1, 2, and 3 at all times (all p < 0.05). The most common CPAK type was type (I + II) (constitutional: apex distal JLO) + type (V + VI) (postoperative 3 months: neutral JLO) in Group 1 (29.4%; p = 0.000); otherwise, the most common CPAK type was type (IV + V) (constitutional: neutral JLO) + type (VIII + IX) (postoperative 3 months: apex proximal JLO) in Group 3 (11.7%; p = 0.000). Clinical outcomes did not differ between the groups.

CONCLUSION

Constitutional and postoperative JLO were predictive factors of postoperative alignment changes after OWHTO. Constitutional apex distal and postoperative neutral JLO had a tendency for varus alignment progression, whereas constitutional neutral and postoperative apex proximal JLO had a tendency for valgus alignment progression.

LEVEL OF EVIDENCE

Retrospective cohort study; Level III.

Outcomes of Distal Medial Collateral Ligament Release During Opening-Wedge High Tibial Osteotomy

Background

During opening-wedge, high-tibial osteotomy (OWHTO), various methods of managing the superficial medial collateral ligament (sMCL) can be performed to obtain a sufficient medial side opening.

Purpose/Hypothesis

The purpose of this study was to evaluate the outcomes of distal sMCL release during OWHTO. It was hypothesized that distal sMCL release would not cause valgus instability.

Study Design

Case series; Level of evidence, 4.

Methods

This retrospective study included 77 patients who underwent OWHTO between January 1, 2018, and October 31, 2019, and completed serial radiological assessments including weightbearing line ratio (WBLR), medial proximal tibial angle (MPTA), coronal translation, total tibial plateau inclination (TTPI), valgus medial joint-space width (valgus-MJSW), valgus joint-line convergence angle (valgus-JLCA), varus lateral joint-space width (varus-LJSW), and varus joint-line convergence angle (varus-JLCA) on standing whole-leg and varus-valgus stress radiographs. Subgroup analysis of pre- to postoperative changes in radiologic parameters was performed according to TTPI (group 1: <25th percentile, group 2: 25th-75th percentile, group 3: >75th percentile) and Ahlbäck osteoarthritis classification (group 1: Ahlbäck grade 1, group 2: Ahlbäck grades 2 and 3).

Results

The mean time to final follow-up was 34.6 ± 6.4 months. The WBLR and coronal translation did not change significantly over the follow-up period. The valgus-MJSW at 6 months postoperatively was significantly wider than that preoperatively and at 1 year postoperatively (P < .001). The varus-LJSW at 6 months postoperatively was significantly wider compared with preoperatively and 1 year postoperatively (P < .001), and the varus-LJSW at 1 year postoperatively was wider than that found preoperatively. Coronal translation was significantly more reduced for patients in TTPI group 1 versus group 3 (P = .019). There was no significant differences according to the Ahlbäck groups. All clinical outcomes improved at final follow-up compared with preoperative values (P ≤ .002).

Conclusion

The study findings indicated that sMCL release did not cause valgus instability or valgus overcorrection at 1 year postoperatively, and improved clinical outcomes were seen at the final follow-up compared with preoperative status after OWHTO with sMCL release.

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.

Analysis of the determinant factor of the medial joint space width after medial opening wedge high tibial osteotomy

INTRODUCTION

The decrease in the medial joint space width (MJSW) in patients with osteoarthritis (OA) is proportional to the degree of arthritis. The purpose of this study was to evaluate the affecting factors of the MJSW by serial radiologic assessment after medial open wedge high tibial osteotomy (MOW-HTO).

MATERIALS AND METHODS

Between March 2014 and March 2019, 162 MOW-HTO knees that underwent serial radiologic assessment and follow-up MRI were enrolled. Changes in the MJSW were analyzed by dividing into three groups: group I, low quartile (< 25%); II, middle quartile (25-75%); and III, high quartile (> 75%), according to the magnitude of the MJSW. The correlation between the MJSW and weight-bearing line ratio (WBLR), hip knee ankle angle (HKA), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle (m-LDFA), joint line orientation angle (JLOA), and MRI cartilage status was analyzed. Multiple linear regression analysis was used to analyze factors affecting the amount of change in the MJSW. The clinical outcome was also correlated with the MJSW.

RESULTS

The amount of change in the JLCA, which has the largest beta value (weight-bearing standing anteroposterior (AP) view and 45° flexion posteroanterior view (Rosenberg view) β =  - 0.699 and β = -5.221, both p < 0.001, respectively), had the greatest contribution to the change in the MJSW. The WBLR was also related (standing AP and Rosenberg β = 0.177 and β = 0.264, p = 0.015 and p = 0.004, respectively). There was no statistical difference between the amount of change in the MJSW and the change in cartilage. The clinical outcomes did not differ between the groups.

CONCLUSION

The JLCA was the most important contributing factor for the MJSW, followed by WBLR. This contribution was more pronounced in Rosenberg view than standing AP view. Changes in cartilage status were not related to the MJSW and JLCA. The clinical outcome was not related to the MJSW, either. Level of evidence Cohort study; level III.

Application of SolidWorks software in preoperative planning of high tibial osteotomy

Purpose

Open-wedge high tibial osteotomy (HTO) is a common surgical treatment for medial osteoarthritis in young and active patients. The accuracy of osteotomy is closely associated with postoperative efficacy. The accuracy of digital preoperative planning is higher than that of the preoperative manual measurement and several computer software with varying accuracy and convenience are used for digital preoperative planning. This study aimed to use the SolidWorks software for HTO preoperative planning and to determine its accuracy and reliability in HTO preoperative planning.

Methods

We reviewed the data of 28 patients with 54 with medial compartment knee arthritis who underwent open-wedge HTO preoperative planning using SolidWorks between June 2019 and March 2021. The standard anteroposterior standing whole-leg radiographs were assessed before and 6 weeks after the surgery. The correction angle, weight-bearing line (WBL) ratio, mechanical femorotibial angle (mFTA), and medial proximal tibial angle (MPTA) before and after the surgery were compared. The clinical results were evaluated using the Knee Society score.

Results

At 6 weeks after the surgery, the WBL ratio was corrected from 16.8% to 50.5%, mFTA was corrected from 6.4° varus to 1.2° valgus, and MPTA was corrected from 83.4° to 89.3°. No significant difference was observed between the predicted correction angle before the surgery and the correction angle measured 6 weeks after the surgery (t = -1.745, p = 0.087). The knee score and function score of Knee Society increased from 76.4 and 80.7 before surgery to 95.0 and 95.7, respectively.

Conclusions

The SolidWorks software showed high accuracy and reliability in preoperative planning of open-wedge HTO in patients with medial compartment knee arthritis.

Factors Associated With Unfavorable Radiological Outcomes After Opening-Wedge High Tibial Osteotomy for Varus Knees

BACKGROUND

Corrective osteotomy around the knee is based on deformity profiles of the femoral and tibial sides. Opening-wedge high tibial osteotomy (OWHTO) can be favored if the outcomes are not different, even if there is a certain degree of abnormal parameters after correction.

PURPOSE/HYPOTHESIS

The purpose of this study was to identify the factors associated with unfavorable radiological outcomes after OWHTO for varus knees. Our hypothesis was that there would be an optimal situation in which double-level osteotomy (DLO) has advantages over isolated OWHTO and an optimal cutoff value of structural parameters for which DLO should be considered in patients with severe varus knees.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The radiological and clinical outcomes of 337 patients who underwent OWHTO were retrospectively evaluated. A subgroup analysis was performed according to the weightbearing line ratio (WBLR) (group 1: <25th percentile; group 2: 25th-75th percentile; and group 3: >75th percentile) and factors associated with unfavorable radiological outcomes. For the assessment of cutoff values of the parameters favoring DLO, unfavorable radiological outcomes were categorized as follows: (1) medial proximal tibial angle (MPTA) >95°, (2) joint-line convergence angle (JLCA) >4° (insufficient medial release), (3) JLCA <0° (medial instability), (4) recurrence of a varus deformity, and (5) lateral hinge fracture.

RESULTS

The mean follow-up period was 66.2 ± 19.1 months. A low preoperative WBLR was related to a larger preoperative to postoperative change (Δ) in the WBLR, a larger reduction in coronal translation, a larger ΔMPTA, a wide preoperative lateral joint space, and a narrow preoperative medial joint space (P < .001, P < .001, P < .001, P = .016, and P = .003, respectively). However, only an MPTA >95° was significantly related to a low WBLR in the subgroup analysis according to unfavorable radiological outcomes (P = .038). The cutoff value of ΔWBLR causing an MPTA >95° was 46.5%, which showed a good area under the curve of 0.800, with a sensitivity of 74.4% and a specificity of 82.7%. The clinical outcomes significantly improved at the final follow-up compared with those preoperatively, with no significant differences between the WBLR groups.

CONCLUSION

A ΔWBLR ≥46.5% led to an MPTA >95°. However, clinical outcomes were not affected. DLO should be considered if the surgeon desires a postoperative MPTA ≤95°.

Editorial Commentary: Patient-Specific Instrumentation for Knee High Tibial Osteotomy Addresses the Bony but Not the Soft-Tissue Aspect of Deformity Correction

Both bony and soft-tissue components should be considered during preoperative planning and intraoperative performance of knee high tibial osteotomy to achieve accurate correction. 3D-printed patient-specific instrumentation may aid in addressing the bony component. Even with appropriate preoperative planning for bony and soft-tissue correction, appropriate adjustments must be made intraoperatively to achieve successful outcomes, and accurate correction is impossible unless the soft-tissue component is considered.

Association of the joint line orientation angle of the contralateral limb with the alignment change of the unilateral and bilateral opening-wedge high tibial osteotomy

PURPOSE

This study aimed to evaluate and compare unilateral and bilateral open-wedge high tibial osteotomy (OWHTO) using mid-term serial assessment of clinical and radiological outcomes, especially focussing on coronal lower extremity alignment.

METHODS

Serial radiological assessments were performed in 40 patients (80 knees) with bilateral OWHTO and 49 patients (49 knees) with unilateral OWHTO. Both groups were further divided into four subgroups to compare each limb (unilateral involved and non-involved limbs and bilateral primarily and secondarily treated limbs). Radiological and clinical outcomes were evaluated and compared among the four groups. For the alignment change assessment, the pelvic tilt angle (PTA), weight-bearing line ratio (WBLR), joint line orientation angle (JLOA), medial proximal tibia angle (MPTA), joint line convergence angle (JLCA), distal tibia articular angle (DTAA), and talar inclination (TI) were measured pre- and postoperatively at 3, 6, and 12 months and annually thereafter. Student's t-test, one-way repeated-measures analysis of variance, and correlation analysis were used to compare the groups.

RESULTS

Patients in the unilateral and bilateral OWHTO groups had similar postoperative radiological and clinical outcomes. Each unilaterally involved limb and primarily treated bilaterally involved limb were negatively affected by the contralateral limb with respect to increased JLOA during the postoperative period (unilateral OWHTO group: r = -0.350, p = 0.023; bilateral OWHTO group: r = -0.520, p = 0.005). The correction change of the ankle parameters in the secondarily treated limb showed greater varus alignment than the primarily treated limb after bilateral OWHTO (DTAA (0.1 ± 3.0 vs. -0.5 ± 3.8°, p = 0.014) and TI (0.9 ± 3.2° vs. -0.3 ± 2.9, p = 0.001)).

CONCLUSION

Unilateral and bilateral OWHTOs shared similar postoperative radiological and clinical outcomes. Alignment changes of the unilateral OWHTO and the primarily treated limb of the bilateral OWHTO were associated with the JLOA of the contralateral limb.

LEVEL OF EVIDENCE

Cohort study; Level III.

Excessively Increased Joint-Line Obliquity After Medial Opening-Wedge High Tibial Osteotomy Is Associated With Inferior Radiologic and Clinical Outcomes: What Is Permissible Joint-Line Obliquity

PURPOSE

This study aimed to evaluate the permissible joint-line obliquity (JLO) based on radiologic and clinical outcomes with midterm follow-up after medial open-wedge high tibial osteotomy (MOWHTO).

METHODS

Patients who had undergone MOWHTO from March 2014 to May 2016 were retrospectively evaluated. They were divided into 4 groups based on JLO as represented by postoperative medial proximal tibial angle (MPTA). Radiologic parameters including MPTA, joint-line orientation angle (JLOA), joint-line convergence angle (JLCA), posterior tibial slope, weightbearing line ratio (WBLR), and coronal translation were analyzed. Clinical outcomes were evaluated with American Knee Society Score (AKSS), Western Ontario and McMaster University Index, and short-form 36 health survey (SF-36). The changes between preoperation and final follow-up in JLOA and MPTA were defined as ΔJLOA and ΔMPTA.

RESULTS

A total of 135 knees were finally included (MPTA ≤90.32° as group I; 90.33° to 92.62° as group II; 92.74° to 95.22° as group III; and ≥95.23° as group IV). The last follow-up MPTA, JLOA, and JLCA values were different between the groups (P < .001, P < .001, and P = .015, respectively). WBLR and JLOA positively correlated with MPTA; however, WBLR showed an abrupt increase at MPTA >96.5°, and the JLOA distribution tended to be greater than the regression line at MPTA >96°. Moreover, ΔJLOA was not as large as ΔMPTA. The percentage of patients attaining a minimal clinically important difference was significantly lower in the AKSS-functional score and SF-36 physical component summary in group IV (P = .008 and 0.021, respectively).

CONCLUSION

The JLOA did not change as much as the MPTA, but an MPTA >95.2° abruptly increased the JLOA and valgus overcorrection after MOWHTO. Poor clinical outcomes were more evident in excessive MPTA (>95.2°) than in mildly undercorrected or properly corrected MPTA (<95.2°).

LEVEL OF EVIDENCE

III, retrospective cohort study.

Comparative Analysis of Serial Union Patterns After Opening-Wedge High Tibial Osteotomy with and without Bone-Void Fillers

BACKGROUND

Opening-wedge high tibial osteotomy produces opening gaps; however, there is little consensus on bone graft necessity and the material that would produce a superior union. The purposes of the present study were (1) to compare the serial union patterns associated with various bone-void fillers, (2) to determine whether bone-void filler is necessary to achieve bone union of the opening gap, and (3) to determine whether bone union is different according to the correction degree during opening-wedge high tibial osteotomy.

METHODS

In this retrospective study, 97 knees were randomly assigned to treatment with hydroxyapatite chip bone (Group A), allogenic chip bone (Group B), or no bone graft (Group C) and were analyzed after a minimum 1-year follow-up. To compare the bone union pattern, the area of callus filling located at the most medial side on an anteroposterior radiograph of the knee was recorded, and a modified van Hemert scoring system was used in the mediolaterally divided 5 zones. The correlations between the correction degree and bone union scores were evaluated.

RESULTS

There were no significant differences in the extent of mediolateral bone-healing at 6 weeks or 3 months postoperatively (p = 0.172 and p = 0.228). However, Group C showed more prominent progression of the gap filling to the medial side compared with Groups A and B at 6 months postoperatively (p = 0.002). Group C showed slow progression of bone union up to 6 weeks but surpassed the other groups at 6 months. The union pattern was not different between Groups A and B, and the correction degree was not correlated with bone union beyond 3 months postoperatively.

CONCLUSIONS

Despite the different gap-healing patterns, opening-wedge high tibial osteotomy without bone graft achieved bone union comparable with allogenic and synthetic graft materials. Group C (no bone graft) showed slower progression of bone union but surpassed the other groups at around 6 months. Based on the union pattern, there was no difference depending on the correction degree and the use of bone-void fillers.

LEVEL OF EVIDENCE

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

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.