Different changes in slope between the medial and lateral tibial plateau after open-wedge high tibial osteotomy

Surgical strategy and complication management of osteotomy around the painful degenerative varus knee: ESSKA Formal Consensus Part II

PURPOSE

The purpose of the European consensus was to provide recommendations for the treatment of patients with a painful degenerative varus knee using a joint preservation approach. Part II focused on surgery, rehabilitation and complications after tibial or femoral correction osteotomy.

METHODS

Ninety-four orthopaedic surgeons from 24 countries across Europe were involved in the consensus, which focused on osteotomies around the knee. The consensus was performed according to the European Society for Sports Traumatology, Knee Surgery and Arthroscopy consensus methodology. The steering group designed the questions and prepared the statements based on the experience of the experts and the evidence of the literature. The statements were evaluated by the ratings of the peer-review groups before a final consensus was released.

RESULTS

The ideal hinge position for medial opening wedge high tibial osteotomy (MOW HTO) should be at the upper level of the proximal tibiofibular joint, and for lateral closing wedge distal femoral osteotomy (LCW DFO) just above the medial femoral condyle. Hinge protection is not mandatory. Biplanar osteotomy cuts provide more stability and quicker bony union for both MOW HTO and LCW DFO and are especially recommended for the latter. Osteotomy gap filling is not mandatory, unless structural augmentation for stability is required. Patient-specific instrumentation should be reserved for complex cases by experienced hands. Early full weight-bearing can be adopted after osteotomy, regardless of the technique. However, extra caution should be exercised in DFO patients. Osteotomy patients should return to sports within 6 months.

CONCLUSION

Clear recommendations for surgical strategy, rehabilitation and complications of knee osteotomies for the painful degenerative varus knee were demonstrated. In Part 2 of the consensus, high levels of agreement were reached by experts throughout Europe, under variable working conditions. Where science is limited, the collated expertise of the collaborators aimed at providing guidance for orthopaedic surgeons developing an interest in the field and highlighting areas for potential future research.

LEVEL OF EVIDENCE

Level II, consensus.

Radiographic Investigation of Coronal Plane and Patellar Height and Changes Following Tibial Deflection Osteotomy for Correction of Tibial Slope in Combination With ACL Reconstruction

BACKGROUND

A tibial deflexion osteotomy (TDO) is performed to decrease the sagittal tibial slope to reduce the relative risk of anterior cruciate ligament (ACL) reconstruction (ACLR) graft failure. Given that coronal plane osteotomies can cause consequential changes in the sagittal plane to patellar height and tibial slope, potential changes to coronal plane alignment and patellar height can result after a sagittal plane osteotomy.

PURPOSE

To compare preoperative and postoperative coronal plane alignment after TDO, as well as to analyze the effect of the osteotomy on patellar height.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study was conducted on a consecutive series of patients with primary and revision ACLR with concomitant TDO between 2011 and 2022. Inclusion criteria were 1-stage autograft ACLR combined with supratubercular TDO with pre- and 3 months postoperative radiographs of sufficient quality. Indications for TDO were anterior instability requiring ACL revision surgery and a posterior tibial slope (PTS) >9° or a PTS >14° in the primary ACL surgery patients. Anteroposterior and lateral knee radiographs were reviewed, and the medial proximal tibial angle (MPTA), PTS, Caton-Deschamps index (CDI), and modified Insall-Salvati ratio were measured directly from the radiographs by 2 independent reviewers.

RESULTS

A total of 68 patients were included in this study. Pre- and postoperative radiographs were performed 1 month before and 3 months after surgery, respectively. There was a significant increase in the mean MPTA of 0.95° varus (SD, 2.1°; range, increase of 4.23° valgus to increase of 7.74° varus; P < .01), a decreased PTS of 8.86° (SD, 3.03°; P < .01), and an increased CDI of 0.08 (range, decrease of 0.27 to increase of 0.64) (P < .01; SD, 0.17) in patients undergoing TDO. Insall-Salvati ratio measurements showed no difference. There was good intra- and interobserver reliability, with intraclass correlation coefficients of 0.97 and 0.91 for MPTA, 0.97 and 0.87 for PTS, 0.87 and 0.93 for CDI, and 0.88 and 0.76 the Insall-Salvati ratio.

CONCLUSION

This study, the largest series on TDO for ACLR, demonstrates that the TDO can be performed safely without large changes to coronal alignment or patellar height. The tibial slope was reduced by a mean of 8.86° (range, 2.3°-11.5°; P < .01). The TDO produces a small statistically significant change to coronal alignment, inducing a mean increased varus of <1° and an increased patellar height of 0.1 CDI. Therefore, TDO can be performed safely without dramatic changes to coronal alignment or patellar height, this study highlights technical aspects to minimize iatrogenic varus.

Changes in sagittal and axial plane alignment in medial opening wedge high tibial osteotomy: a prospective observational study

PURPOSE

Deformity correction during high tibial osteotomy is generally based on coronal plane alignment. The aim of this study was to measure changes in sagittal and axial plane alignment following medial opening wedge high tibial osteotomy [mHTO], using pre- and postoperative computed tomography [CT] scans, and correlate them with changes in coronal plane. The secondary objective was to correlate changes in functional outcomes with changes in alignment in each plane. The null hypothesis was that sagittal and axial plane alignment does not change significantly following mHTO.

METHODS

This was a prospective, observational study including 30 patients of isolated medial compartment osteoarthritis of the knee joint, between 30 and 60 years of age. Preoperative and postoperative computed tomography scan of bilateral lower limbs from hip to ankle was performed. Varus angle, mechanical axis deviation [MAD] of the lower limb, medial proximal tibial angle [MPTA], tibial torsion and posterior proximal tibial angle [PPTA] were measured. Visual Analogue Scale [VAS 0-10 cm scale] was used for assessment of pain. Functional outcomes were evaluated using Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], 12 Item Short Form Survey [SF 12] and Tegner Lysholm knee scoring scale.

RESULTS

Mean age of patients was 44.59 ± 8.157 years. Mean preoperative varus deformity was 11.13 ± 1.5 degrees, which got corrected to a mean valgus alignment of 3.8 ± 0.93 degrees postoperatively. The mechanical axis deviation was 4.32 ± 1.76 mm lateral to the knee joint center postoperatively. Preoperatively, all knees had external tibial torsion [27.08 ± 2.18 degrees] which was corrected to a mean external tibial torsion of 19.80 ± 3.72 degree after the surgery [P < 0.001]. The overall decrease in sagittal alignment in the present study was 3.70 ± 3.14 degree, 3.97 ± 3.06 degree, 3.92 ± 2.33 degree, for medial, middle and lateral cuts, respectively. There was a significant correlation between change in varus/valgus angle and change in TT and PPTA. Significant positive correlation was seen between change in coronal alignment and functional outcome scores.

CONCLUSION

This study has shown that mHTO significantly changes torsional and sagittal alignment. This is the first study to establish relation between correction in coronal plane and associated changes in sagittal and torsional alignments.

The influence of different hinge position on PTS during HTO: comparison between open-wedge and closed-wedge HTO

PURPOSE

The purpose of this study was to determine the significance of hinge position through comparison between open-wedge and closed-wedge high tibial osteotomy (HTO) and to determine the ideal hinge position to minimize the effect of HTO on the posterior tibial slope (PTS) and medial proximal tibial angle (MPTA).

METHODS

Procedures were performed on 32 cadaveric knees using open-wedge HTO with the standard hinge position or a low hinge position or closed-wedge HTO with the standard hinge position or a low hinge position. To define the standard hinge position in open wedge HTO, we drew a line 3-cm inferior to the medial tibial plateau toward the fibular head and located the intersection of this line with a longitudinal line 1-cm medial to fibular shaft. The low hinge position was then defined as the point 1-cm inferior to the standard position. For the standard hinge position for closed-wedge HTO, we drew a line parallel with joint line from 2-cm inferior to the lateral tibial plateau. The low hinge position was then defined as the point 1-cm inferior to the standard position.

RESULTS

For the open-wedge procedure, osteotomy through the low hinge position resulted in a significantly greater PTS compared to osteotomy through the standard hinge position. MPTA was also significantly greater for the low hinge position compared to standard hinge position. In the closed-wedge HTO, neither the PTS nor MPTA was significantly different for the low and standard hinge positions.

CONCLUSIONS

Hinge position significantly affects changes in the PTS and MPTA following open-wedge but not closed-wedge HTO. Understanding how to hinge position affects the PTS and MPTA is critical for surgeons performing open-wedge HTO procedures. Adopting an accurate hinge position is crucial for preventing complications, especially in open-wedge osteotomy, due to postoperative changes in the PTS and MPTA.

Use of a suspended and straightened knee joint position when fixing steel plates can prevent the increase in postoperative posterior tibial slope after open‑wedge high tibial osteotomy

BACKGROUND

Posterior tibial slope (PTS) increases after medial open-wedge high tibial osteotomy (OWHTO) is challenging for patients. This study aims to determine whether use of a suspended and straightened knee joint position during the fixing of steel plates can prevent an increase in the PTS after OWHTO.

METHODS

This study retrospectively analyzed 112 subjects (122 knees) [34 males, 78 females; mean age 59.1 ± 6.6 (range 48-76) years; mean body mass index 28.06 ± 3.61 kg/m²] who underwent OWHTO. A total of 78 knees that were suspended and extended by placing a sterile cloth ball under the ipsilateral ankle during the fixing of steel plates comprised the suspended and straightened knee joint position (SSP) group, and 44 knees that were kept naturally straightened without placing a sterile cloth ball under the ipsilateral ankle during the fixing of steel plates comprised the naturally straightened knee joint position (NSP) group. Patients were clinically assessed according to the visual analog pain scale (VAS), the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index, the Knee Society Scores (KSS) knee and function scores, the Hospital for Special Surgery (HSS) knee scores and the Lysholm knee scores. Radiological assessment was performed according to the changes in the PTS between preoperation, 1-day postoperation, and the final follow-up periods. Ultimately, the difference in postoperative PTS changes between the two groups was statistically analyzed. The median follow-up period was 2.2 years (range 1.6-3.7 years).

RESULTS

In the final follow-up period, significant improvements were observed in the clinical VAS scores, WOMAC scores, KSS knee and function scores, HSS scores and the Lysholm knee scores in both groups (P < 0.001), and no difference was found between the two groups. Radiological assessment showed that there was no statistical difference in the preoperative PTS between the two groups. The 1-day postoperative PTS and the most recent follow-up PTS were significantly greater than the preoperative PTS in the NSP group (t = - 3.213, - 6.406, all P < 0.001), but no significant increase was seen in the SSP group (P > 0.05). The increase in PTS in the NSP group was significantly greater than that in the SSP group at the 1-day postoperative (t = 2.243, P = 0.030) and final follow-up periods (t = 6.501, P < 0.001).

CONCLUSIONS

For OWHTO, the use of a suspended and straightened knee joint position rather than a naturally straightened knee joint position during the fixing of steel plates could effectively prevent the increase in postoperative PTS.

LEVEL OF EVIDENCE

Retrospective Study Level III.

Femur originated genu varum in a patient with symptomatic ACL deficiency: a case report and review of literature

Background

Anterior cruciate ligament (ACL) injury may be associated with genu varum. There are a few indications in which the varus deformity can be corrected at the time of ACL reconstruction. However, as the genu varum originates mostly from the tibia and the simultaneous presence of ACL deficiency and femur originated genu varum is uncommon, only a few papers have described their management for ACL deficient patients with femur originated genu varum.

Case presentation

A young patient visited our clinic with a complaint of right knee pain and giving way. Further work up revealed a full mid substance ACL tear, mild medial knee osteoarthritis and femur originated genu varum of his right knee. He was managed with simultaneous ACL reconstruction and distal femoral valgus osteotomy.

Conclusions

Any corrective osteotomy for genu varum should be performed at center of rotation angle. Isolated ACL reconstruction in patients with simultaneous ACL deficiency and genu varum may hasten the knee degeneration.

Level of evidence

IV

Changes in Coronal Alignment of the Knee Joint after Supramalleolar Osteotomy

BACKGROUND

Assessing knee joint orientation changes after SMO may help clinical advancement in managing patients with ipsilateral ankle and knee joint arthritis. However, knee joint changes after supramalleolar osteotomy (SMO) have not been reported. We investigated changes in coronal alignment of the knee joint after SMO.

METHODS

In this multicentre study, from January 2014 to December 2018, 47 ankles with varus osteoarthritis treated with SMO were retrospectively identified. Ankle joint changes were assessed using the tibiotalar angle, talar tilt angle, and lateral distal tibial angle (LDTA); knee joint changes using the medial proximal tibial angle (MPTA), medial and lateral joint space widths (mJSW and lJSW, respectively), and medial and lateral joint line convergence angles (JLCA); and lower limb alignment changes using mechanical axis deviation angle (MADA) and the hip-knee-ankle (HKA) angle measured on full-length anteroposterior radiographs of the lower extremity. Correlation analysis and binary logistic regression analysis were performed.

RESULTS

Postoperatively, LDTA (p < 0.001) and tibiotalar angle (p < 0.001) significantly changed, indicating meaningful improvement in the ankle joint varus deformity. Regarding the knee joint changes, JLCA significantly changed into valgus direction (p = 0.044). As for lower limb alignment changes, MADA significantly decreased (p < 0.001), whereas the HKA angle significantly increased (p < 0.001). In univariate and multivariate logistic regression analyses, changes in the MADA (p < 0.001) and the HKA angle (p < 0.001) were significantly correlated with the correction angle.

CONCLUSIONS

SMO remarkably improves ankle joint varus deformity, followed by significant lower limb alignment changes. Despite meaningful changes in JLCA, the relationship between the amount of osteotomy near the ankle joint and improvement in knee joint radiographic parameters was not significant. Radiographic parameters of the knee joint would less likely be changed following SMO.

Proximal Fibular Osteotomy: Biomechanics, Indications, Technique, and Results

The evidence base is growing regarding proximal fibular osteotomy. Most studies show that the pain relief and improvement in terms of radiology is statistically significant. More understandable biomechanical theories explaining this improvement are appearing. Because it has a low complication rate and is relatively easy to execute, proximal fibular osteotomy should definitely be considered in any algorithm for the treatment of medial compartment osteoarthritis of the knee. [Orthopedics. 2020;43(6):e627-e631.].

The relationship between the posterior tibial slope and the sagittal femoral condylar shape: Two circles and ellipses

BACKGROUND

Whether the posterior tibial slope (PTS) is associated with the femoral condylar shape has remained unclear. Classical anatomical studies considered the sagittal profiles of femoral condyles to consist of two circles. Recently, an elliptical method was described to simplify the "two circles" model. Our purpose was to analyze the relationship between the PTS and the shape of the sagittal femoral condyle, that is, two circles and two ellipses, using magnetic resonance imaging (MRI) scans.

METHODS

Eighty right knees of healthy subjects were scanned by MRI at full extension. The medial and lateral PTS were measured (mPTS and lPTS). On the distal-most medial and lateral slices, the femoral condylar articular surfaces were best fitted by circles or ellipses, respectively. The radii of the medial and lateral posterior circles and inferior circles (r_m and r_l , R_m and R_l , respectively), the semi-major axes and the semi-minor axes of the medial and lateral ellipses (a_m and a_l , b_m and b_l , respectively), and the r_m /R_m , b_m /a_m , r_l /R_l , b_l /a_l ratios were measured and calculated.

RESULTS

mPTS correlated significantly with the parameters of the medial condyle (all p < .05) and the ratios b_m /a_m and r_m /R_m (p = .017 and p = .027, respectively). However, the lPTS did not correlate with the parameters of the lateral condyle (all p > .05) or the ratios b_l /a_l and r_l /R_l (p = .461 and p = .241, respectively).

CONCLUSION

The mPTS is associated with the sagittal shape of the medial femoral condyle but the lPTS is not. Both two circles and two ellipses are feasible ways to represent the sagittal femoral condylar shape.

Anterior cruciate ligament reconstruction with anterior closing wedge osteotomy for failed high tibial osteotomy-A case report

•

High posterior tibial slope is a risk factor for anterior cruciate ligament deficiency.

•

Knee instability from increased posterior tibial slope is not a reported complication after open wedge high tibial osteotomy.

•

Anterior cruciate ligament reconstruction using the quadriceps tendon and tibial anterior closing wedge osteotomy is a good treatment option.

Background

Increased posterior tibial slope (PTS) is considered a risk factor for anterior cruciate ligament (ACL) injury. Previous studies revealed that medial opening wedge high tibial osteotomy (OWHTO) tends to increase PTS. However, knee instability from increased PTS is not a reported complication after OWHTO, and the treatment strategy is unclear.

Methods

A 55-year-old woman who complained of left knee pain underwent OWHTO for early-stage medial compartment osteoarthritis by another doctor. After the first surgery, her left knee pain decreased; however, 1 year after OWHTO, she began to feel left knee instability, and the primary doctor consulted our clinic. Physical examination revealed a positive Lachman's test, and radiographs showed that PTS had increased from 8 degrees to 15 degrees. According to these findings, we diagnosed an aggravated symptomatic knee instability secondary to increased PTS after OWHTO. We then performed ACL reconstruction using the quadriceps tendon and tibial anterior closing wedge osteotomy (ACWO), which is a newly-developed technique to correct PTS for revision ACL reconstruction.

Results

Postoperatively, PTS was corrected from 15 degrees to 7 degrees, and the patient's Lysholm score improved from 39 to 95, 1 year postoperatively.

Conclusions

ACL reconstruction with ACWO is a possible treatment option for the PTS-increased knee after OWHTO.

Effects of sagittal tibial osteotomy on frontal alignment of the knee and patellar height

AIM OF THE STUDY

The aim of this study was to evaluate the radiographic effect of sagittal tibial osteotomy (STO), flexion tibial osteotomy (FTO) and deflexion tibial osteotomy (DTO) around the knee. It has been hypothesized that proximal STO modifies patellar height and could cause varus/valgus changes of the anatomical tibial axis: The purpose of the study was to verify this and to analyse these modifications.

METHOD

Patients underwent proximal STO in our department between 2007 and 2018: overall 28 consecutive patients (19 males, 9 females; 28 knees). Twelve patients underwent DTO, and 16 patients underwent FTO. Two independent observers measured the pre-operative and post-operative radiological indexes: posterior tibial slope, Caton-Deschamps Index (CDI) and Modified Insall-Salvati Index (MISI) in the lateral views; medial Tibial Plateau-Tibial Shaft (mTPTS) and medial Femoral Shaft-Tibial Shaft (mFTA) anatomical angles were measured in the frontal plane.

RESULTS

No complications were reported at the average follow-up of 1.6 ± 1.1 years. The mean mTPTS significantly increased from 0.6° ± 2.4° pre-operatively to 2.9° ± 2.6° of varus post-operatively (DTO (pre-operative 0.3 ± 3.1°, post-operative 2.4 ± 2.1°, ns); FTO (pre-operative 0.9 ± 1.9°, post-operative 3.2 ± 3.0°, P < 0.05)). The mean mFTA significantly reduced from 186.2° ± 4.9° pre-operatively to 182.7° ± 3.9° post-operatively (DTO (pre-operative 183.4 ± 3.3°, post-operative 180.6 ± 3.5°, ns); FTO (pre-operative 188.5 ± 4.9°, post-operative 184.4 ± 3.4°, P < 0.05)). The overall analysis reported no differences statistically significant in patellar height indexes.

DISCUSSION

The main finding of this study is that STO slightly modifies tibial anatomical axes. This finding is more evident in FTOs. This surgical technique, due to its design, does not influence the patellar height. The tibial tuberosity osteotomy, performed in most of the cases to better expose tibial metaphysis and to avoid patellar tendon damages, provides another benefit that is the possibility to easily preserve the native patellar height.

CONCLUSION

Sagittal tibial osteotomies slightly modify tibial anatomical axes in frontal plan without influencing the patellar height. This surgical procedure resulted to be effective and reliable in correcting the sagittal knee alignment but reporting, particularly of FTO, varus changes of anatomical tibial axis.

High tibial osteotomy in a lax knee: A review of current concepts

The technique of high tibial osteotomy (HTO) was traditionally documented for symptomatic medial tibiofemoral arthrosis associated with coronal plane malalignment in a stable knee., recently, more attention has been given to the treatment of coronal malalignment in lax knees with HTO with or without ligament reconstruction. Patients with overwhelming pain, chronic ligament deficiency and coronal or sagittal deformity are generally easier to treat with HTO as compared to those who have mild pain and a proximal tibial deformity. The instability at the knee joint can be either in the coronal or sagittal plane or in both planes. Younger patients with chronic ACL deficiency, varus malalignment and advanced medial compartment arthritis, who present with pain and slight instability show satisfactory results with HTO. Double-limb weight bearing anteroposterior view radiographs are used to plot mechanical leg axis (from the centre of the femoral head to the centre of the knee), anatomical axis (a line from the centre of the piriformis fossa to the centre of the knee joint and a line through the long axis of tibia) and weight bearing axis (line drawn from the centre of the femoral head to the centre of the ankle joint) and are used to plan HTO. A 3-dimensional pre-operative plan using CT and MRI is recently studied. The decision to perform HTO alone or in combination with ligament reconstruction involves consideration of patient demographics, symptoms and ligaments involved. The most commonly used surgical techniques for high tibial osteotomy include lateral close wedge osteotomy, medial open wedge osteotomy and dome osteotomy. The post-operative rehabilitation depends on the rigidity of fixation.

Morphologic MRI changes of the anterior cruciate ligament are associated with an increase in the medial tibial plateau bony slope after medial opening wedge high tibial osteotomy in a non-injured ACL population

BACKGROUND

Medial opening wedge high tibial osteotomy (OWHTO) is a useful treatment for medial osteoarthritis. However, OWHTO sometimes causes a change in tibial slope in the sagittal plane. Although several studies have described the effects of the tibial slope on the biomechanics of the knee, including the anterior cruciate ligament (ACL), there has been little study of the magnetic resonance imaging (MRI) visible changes occurring to the native ACL and the factors affecting them after OWHTO.

HYPOTHESIS

We hypothesized that morphologic MRI changes to an uninjured ACL after OWHTO would be associated with increased medial tibial plateau bony slope.

PATIENTS AND METHODS

Thirty-three patients who underwent OWHTO and pre/postoperative MRI were included in this retrospective study. The mean period of follow-up MRI was 22.35 (±14.78) months. The patients were divided into two groups according to the occurrence of postoperative ACL morphologic MRI changes defined as mucoid degeneration, ganglion cyst occurrence, or change in the ACL fiber shape (stationary group n=21, altered group n=12). The medial tibial plateau bony slope (MTS) and anterior tibial translation (ATT) were evaluated on MRI. Logistic regression analysis was used to determine factors affecting the occurrence of postoperative ACL morphologic changes.

RESULTS

Postoperative MTS and the difference between pre- and post values (ΔMTS), postoperative ATT and the difference between pre- and post values (ΔATT) were significantly different between stationary and altered groups. ΔMTS was associated with postoperative morphologic changes to the ACL (odds ratio: 0.30, 95% confidence interval=0.11-0.82, p=0.019).

CONCLUSION

The occurrence of morphologic ACL change after OWHTO is associated with the amount of MTS change.

LEVEL OF EVIDENCE

III, Retrospective comparative study.

Effect of increased posterior tibial slope on the anterior cruciate ligament status in medial open wedge high tibial osteotomy in an uninjured ACL population

PURPOSE

The purpose of this study was to clarify the relationship between posterior tibial slope angle (PTSA) and anterior cruciate ligament (ACL) status in medial open wedge high tibial osteotomy (OWHTO). Our hypothesis was that even though OWHTO may improve anteroposterior laxity of the knee, an increase in PTSA after OWHTO would be associated with ACL degeneration.

METHODS

Seventy-five patients treated with OWHTO were retrospectively analyzed. PTSA were evaluated radiographically pre- and postoperatively. The ACL was evaluated during the index arthroscopy at the time of OWHTO and a second-look arthroscopy during the plate removal, and scored from 1 (normal ACL) to 4 (complete tear). An anterior tibial translation (ATT) test was performed.

RESULTS

The mean time period from the index to second-look arthroscopy was 15.0±4.4months. PTSA significantly increased from 5.3±3.4° preoperatively to 7.5±4.0° postoperatively (p<0.001). The average ACL score significantly increased from 1.9±0.5 at the index arthroscopy to 2.2±0.5 at the second-look arthroscopy (p=0.0025). The average ATT on the operated side significantly decreased from 7.1±2.6mm preoperatively to 5.3±2.3mm at the second-look arthroscopy (p<0.0001). There was a significant positive correlation between the increase in PTSA and the change of ACL grade [correlation coefficient (r)=0.221, p<0.05].

CONCLUSION

Even though OWHTO reduces anteroposterior knee laxity, an increase in PTSA is associated with ACL degeneration. It is important for the surgeon to avoid an increase in PTSA during the intervention to prevent ACL degeneration after OWHTO.

LEVEL OF EVIDENCE

IV, therapeutic retrospective case series.

Effect of Fibular Height and Lateral Tibial Condylar Geometry on Lateral Cortical Hinge Fracture in Open Wedge High Tibial Osteotomy

PURPOSE

To evaluate whether the fibular position and lateral proximal tibial geometry affect the osteotomy configuration and lateral hinge fracture (LHF) during open wedge high tibial osteotomy (OWHTO).

METHODS

From March 2014 to January 2016, patients who underwent OWHTO for isolated medial compartment osteoarthritis of the knee were retrospectively reviewed. To identify whether the fibular position and lateral proximal tibial geometry affect the osteotomy configuration, the fibular height, fibular anteroposterior position, lateral tibial condylar width, and lateral tibial condylar slope were evaluated on plain radiograph or computed tomography (CT). Thereafter, the correlation of these parameters with the thickness of the proximal fragment around the osteotomy end and LHFs was determined.

RESULTS

A total of 123 OWHTOs including 30 LHFs (24.3%) were evaluated. High fibular head and small tibial condylar width and slope were related to thin thickness of the proximal tibial fragment, particularly on the posterior side (fibular height, P = .005; condylar width, P = .002; condylar slope, P = .01). The fibular height was shorter in the LHF group than in the non-LHF group on both plain radiography and CT (fibular height [plain radiography], 18.3 ± 1.6 vs 20.2 ± 2.1 mm; P < .001; fibular height [CT], 17.4 ± 1.1 vs 19.6 ± 2.0 mm; P < .001). The lateral tibial condylar width and slope were also smaller in the LHF group compared with the non-LHF group (tibial condylar width, 21.2 ± 4.9 vs 23.4 ± 4.5 mm; P = .023; tibial condylar slope, 37.7 ± 6.6 vs 41.3 ± 7.6 mm; P = .027).

CONCLUSIONS

The fibular position and lateral proximal tibial geometry affect the osteotomy configuration and LHFs. A highly positioned fibula was related to a small lateral tibial condyle, which induced a thin proximal fragment. This finding was related to a higher risk of LHFs. Therefore, understanding the fibular height and lateral proximal tibial geometry may be helpful for the prediction of the osteotomy configuration and development of LHFs.

LEVEL OF EVIDENCE

Level III, case-control study.

The Use of Navigation in Osteotomies Around the Knee

Osteotomies around the knee for treating osteoarthritis or knee instability are currently well-established procedures. Success of these realignment procedures is based on the accuracy and the reliability of correction angles in the coronal and sagittal alignment. In this context of improving precision and adapting the correction to each patient, navigation is currently being widely used. The rationale for its use is based on understanding the advantages and limitations, technical principles, and potential pitfalls. This article describes these areas and the overall clinical outcomes of this system for knee osteotomies.

Complications Associated With Medial Opening-Wedge High Tibial Osteotomy Using a Locking Plate: A Multicenter Study

BACKGROUND

The aim of this study is to investigate complications following medial opening-wedge high tibial osteotomy using a locking plate. In addition, we aimed to compare postoperative outcomes between the complicated and the uncomplicated group.

METHODS

This study enrolled 209 patients who underwent medial opening-wedge high tibial osteotomy between 2010 and 2015. Patients with a follow-up period of at least 2 years were enrolled. Medical records and radiologic data were retrospectively reviewed. The complications were assessed up to postoperative 2 years and categorized into major and minor complications. The preoperative and postoperative clinical statuses were assessed using the Western Ontario McMaster University Osteoarthritis Index.

RESULTS

The mean patient age was 56.4 ± 5.9 years. Overall complication rate was 29.7%. Minor complications included undisplaced lateral hinge fracture (12.0%), hardware irritation (1.4%), displaced lateral hinge fracture (2.4%), delayed wound healing (1.9%), undisplaced lateral tibial plateau fracture (1%), and superficial wound infection (1%). Major complications were symptomatic hardware which needed hardware removal (4.8%), deep wound infection (1.9%), hardware failure with correction loss (1%), nonunion (0.5%), and early conversion to arthroplasty (0.5%). Most complications occurred intraoperatively (30.6%) and within 3 months postoperatively (40.3%). The major complication group showed a statistically higher Western Ontario McMaster University Osteoarthritis Index score than did other groups at postoperative 1 year (P = .013) and 2 years (P = .001).

CONCLUSION

The overall complication rate was 29.7%. Most complications were minor. The most common complication was undisplaced lateral hinge fracture. Major complications occurred in 8.6%. The major complication group showed significantly worse clinical outcomes than did the uncomplicated and minor complication groups.

External loads associated with anterior cruciate ligament injuries increase the correlation between tibial slope and ligament strain during in vitro simulations of in vivo landings

BACKGROUND

The aim of the present study was to evaluate the relationship between tibial slope angle and ligament strain during in vitro landing simulations that induce ACL failure through the application of variable external loading at the knee. The hypothesis tested was that steeper posterior tibial slope angle would be associated with higher ACL strain during a simulated landing task across all external loading conditions.

METHODS

Kinetics previously derived from an in vivo cohort performing drop landings were reproduced on 45 cadaveric knees via the mechanical impact simulator. MRIs were taken of each specimen and used to calculate medial compartment posterior tibial slope, lateral compartment posterior tibial slope, and coronal plane tibial slope. Linear regression analyses were performed between these angles and ACL strain to determine whether tibial slope was a predictive factor for ACL strain.

FINDINGS

Medial and lateral posterior tibial slope were predictive factors for ACL strain during some landings with higher combined loads. Medial posterior slope was more predictive of ACL strain in most landings for male specimens, while lateral posterior and coronal slope were more predictive in female specimens, but primarily when high abduction moments were applied.

INTERPRETATION

Tibial slope has the potential to influence ACL strain during landing, especially when large abduction moments are present at the knee. Deleterious external loads to the ACL increase the correlation between tibial slope and ACL strain, which indicates that tibial slope angles are an additive factor for athletes apt to generate large out-of-plane knee moments during landing tasks.

Multi-objective design optimization of high tibial osteotomy for improvement of biomechanical effect by using finite element analysis

Medial opening wedge high tibial osteotomy (HTO) makes the proximal tibia a highly unstable structure and causes plates and screws to be the potential sources for mechanical failure. However, asymmetrical callus and incomplete bone formations underneath the plates (TomoFix) have been recent concerns in clinical and experimental studies related to HTO due to the high stiffness. The purpose of this study was to evaluate the biomechanical effect of the TomoFix plate system with respect to changes in design using a computational simulation. A parametric three-dimensional model of HTO was constructed from medical image data. The design parameters for the HTO plate were evaluated to investigate their influence on biomechanical effects, and the most significant factors were determined using Taguchi-style L27 orthogonal arrays. Multi-objective optimization was used to identify the wedge micromotion stability without the stress shielding effect that occurs in the bone plate. The initial design showed that the high stiffness of the plate caused stress shielding on the bone and plate. However, the optimal design led to sharing the stress and load with the bone plate to eliminate stress shielding. In addition, the stability required for the plate could be found in the micromotions of the wedge for the optimal design. The optimal condition of design parameters was successfully determined using the Taguchi and multi-objective optimization method, which was shown to eliminate stress shielding effects. The results showed that an optimal design demonstrated the feasibility of design optimization and improvements in biomechanical stability for HTO. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2956-2965, 2018.

[Osteotomies around the knee for ligament insufficiency]

BACKGROUND

The osseous geometry of the lower limb has a significant impact on knee instability after ligament injuries, and osseous malalignment has been shown to be a significant risk factor for the failure of ligament reconstruction procedures. Therefore, osteotomies around the knee have gained importance as a combined or isolated treatment option in the ligament deficient and malaligned knee. In addition to unloading of an arthritic knee compartment, osteotomies are also performed to protect a reconstructed ligament and to stabilize the joint without ligament surgery.

PROCEDURE

In addition to the correction of varus or valgus malalignment, correction of sagittal imbalance by modifying the tibial slope is an emerging concept. Even small modifications of the tibial slope (≤5°) have been shown to change the anterior-posterior translation in a clinically significant manner. Especially in the case of chronic posterior or posterolateral instability, a valgus-producing and slope-increasing high tibial osteotomy is usually the first treatment option, and ligament surgery is only performed optionally. Isolated modification of the tibial slope is performed infrequently, however, a slope-decreasing osteotomy should be considered in patients with multiple failed ACL reconstructions and a tibial slope of >12°.

The influence of tibial slope on the graft in combined high tibial osteotomy and anterior cruciate ligament reconstruction

BACKGROUND

Young patients with severe medial osteoarthritis, varus malalignment and insufficiency of the anterior cruciate ligament (ACL) are difficult to treat. The tibial slope has gained attention with regard to osteotomies and ligamentous instability. The purpose was to evaluate the outcome of combined high tibial osteotomy (HTO), ACL reconstruction and chondral resurfacing (CR, abrasion plus microfracture), and to analyse graft failure rates with regard to the tibial slope.

METHODS

Fifty cases (48.9 ± 5.4 years) of combined HTO, ACLR and CR were retrospectively analysed with regard to survival, functional outcome (subjective International Knee Documentation Committee (IKDC) examination form) and subjective satisfaction. The tibial slope was determined on lateral radiographs and analysed with regard to its influence on graft functionality at the time of hardware removal.

RESULTS

Follow-up rate was 100% after 5.6 ± 1.6 years. No arthroplasties were performed. Subjective IKDC score was 70 ± 18, and 94% were satisfied with the result. The graft was intact in 39 cases (78%), and non-functional in 11 cases (22%). No significant changes were present in pre- and postoperative tibial slope (P = 0.811). Graft insufficiency was strongly dependent on tibial slope, with a failure rate of seven percent in cases of postoperative tibial slope <7.5°, 24% in cases of 7.5-12.5°, and 36% in cases of >12.5°.

CONCLUSION

Combined HTO, ACLR and CR is an effective treatment in these cases. The graft failure rate increases with an increase in tibial slope, in particular when exceeding 12.5°.

LEVEL OF EVIDENCE

Case series, Level 4.

Longitudinal changes in subchondral bone structure as assessed with MRI are associated with functional outcome after high tibial osteotomy

OBJECTIVES

The primary objective of this study was to evaluate the effects of high tibial osteotomy (HTO) on subchondral bone structure assessed with magnetic resonance (MR)-based trabecular bone imaging and the correlations of these effects with functional outcome and clinical symptoms.

METHODS

Patients with varus malalignment (6.2±2.2°) and without a history of knee surgery (n=22; 3 women; 48.7±10.3 years) were included into this prospective study. 1.5T MR imaging was performed before and on average 1.5 years after HTO (amount of correction 4.7±2.5°) and histomorphometric parameters of the trabecular bone were calculated for the medial/ lateral tibia and femur. Functional outcome was assessed with validated scores focusing on sports activity including the Lysholm Score, Tegner Activity Scale and the adapted Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Score.

RESULTS

Apparent trabecular number significantly decreased in all compartments of the tibiofemoral joint when comparing values before and on average 1.5 years after HTO (P<0.05 for all). Decrease in apparent trabecular number was significantly higher within the medial tibia compared to the lateral compartment (mean difference -0.24 mm^-1 (95% confidence interval (CI): -0.33, -0.14 mm^-1); P<0.001). Apparent trabecular bone thickness significantly increased within 1.5 years after HTO in the lateral femur (P=0.002) and tibia (P <0.001). The Lysholm Score and Tegner Scale demonstrated an improvement of functional outcome, and the adapted WOMAC demonstrated an improvement of pain, stiffness and physical function within 1.5 years after HTO (P<0.01), with the improvement of WOMAC correlating significantly with changes in trabecular bone thickness within the medial tibia (r= -0.48; P=0.01).

CONCLUSION

These findings indicate a reversal of the previous subchondral bone alterations in patients with varus malalignment after undergoing HTO, while pronounced subchondral changes were associated with a better functional outcome.

LEVEL OF EVIDENCE

3.

The effects of different hinge positions on posterior tibial slope in medial open-wedge high tibial osteotomy

PURPOSE

The purpose of this study was to determine the standard hinge position to minimize effects from medial open-wedge high tibial osteotomy (HTO) on the posterior tibial slope.

METHODS

Sixteen cadaveric knees underwent medial open-wedge osteotomy using either the standard or the low hinge position. To define the standard hinge position, a line 3 cm inferior to the medial tibial plateau towards the fibular head and located its intersection with a longitudinal line 1 cm medial to the fibular shaft was drawn. Low hinge position was defined as the point 1 cm inferior to the standard position. After tibial osteotomy, computed tomography scans of each knee were taken and three-dimensional models were constructed to characterize hinge position orientation and measure the osteotomy site effects on posterior tibial slope, medial proximal tibial angle, and gap ratio (the ratio of the anterior to posterior gap in the opened wedge).

RESULTS

In two low hinge position specimens, the tibial lateral cortex hinge fracture occurred. Osteotomy through the low hinge position resulted in significantly greater posterior tibial slope compared to the standard hinge position (mean ± standard deviation) (11.2 ± 3.0° and 5.6 ± 2.5°, respectively; p < 0.001). Medial proximal tibial angle was also significantly greater for low compared to standard hinge position (95.4 ± 3.5° and 88.0 ± 3.5°, respectively; p < 0.001). Gap ratio was not significantly different between the two groups.

CONCLUSION

Hinge position significantly affects the posterior tibial slope and medial proximal tibial angle following medial open-wedge HTO. Accurate hinge position is crucial to prevent complications from changes in posterior tibial slope and medial proximal tibial angle after surgery.

Tibiofemoral joint congruence is lower in females with ACL injuries than males with ACL injuries

PURPOSE

Previous research has demonstrated that women have a higher risk of anterior cruciate ligament (ACL) injury than men. Tibiofemoral articular geometry may play a role in the occurrence of ACL tears. The purpose of this study was to analyze the gender-specific geometric characteristics differences in tibiofemoral morphology in ACL-deficient patients.

METHODS

Medial tibial slope (MTS), lateral tibial slope (LTS), medial tibial plateau concavity, medial and lateral femoral condyle convexity, and lateral plateau convexity were analyzed in 276 patients with complete ACL injuries (138 females and 138 males). Two blinded observers measured the anatomical parameters of tibiofemoral geometry with use of multiplanar CT scans. Intra- and inter-rater reliabilities were assessed and comparisons between anatomic measures were made between male and female patients.

RESULTS

The average ICC for all measurements was 0.90 (range 0.83-0.97) indicating good reliability. Male ACL injured patients demonstrated significantly greater LTS (10.5° ± 2.8) than female patients (9.6° ± 3.5°; p < 0.05). No gender difference in MTS was found (n.s.). Medial and lateral femoral condyle convexity and medial tibial plateau concavity were greater in males than females (all p < 0.05). Lateral tibial plateau convexity in females was higher than in males (p < 0.001). The medial and lateral compartments were found to be more incongruent in females than males (p < 0.01 and p < 0.001, respectively).

CONCLUSIONS

Female patients were noted to have more incongruent medial and lateral compartments than male patients. These gender-specific differences in joint morphology may contribute to graft tear risk and outcomes of ACL reconstruction; however, comparative clinical studies are needed to confirm this possibility.

LEVEL OF EVIDENCE

3.

The correlation of sagittal osteotomy inclination and the anteroposterior translation in medial open-wedge high tibial osteotomy-one of the causes affecting the patellofemoral joint?

PURPOSE

For opening-wedge high tibial osteotomy, previous studies have shown that most osteotomies were anterior-inclined. The purpose of this study was to determine the effect of sagittal osteotomy inclination on the anteroposterior translation of osteomized fragments and discuss its possible impact on the patellofemoral joint.

METHODS

We retrospectively measured the angle between the joint line and the sagittal osteotomy line. We also evaluated the anteroposterior translation of osteomized fragments by measuring the distance from the most posterior point of the tibial plateau to the tibial tuberosity and the anterior cortical line. Correlation between the sagittal osteotomy inclination and the anteroposterior translation of fragments was analyzed.

RESULTS

The mean sagittal osteotomy inclination was 6.3 ± 8.4° anteriorly to the joint line and 82% of osteotomies were anterior-inclined. The anteroposterior translation of the osteomized fragments was moderately correlated to the sagittal inclination. Anterior-inclined osteotomy tends to result in the anterior translation of the proximal fragment.

CONCLUSION

High rates of anterior-inclined osteotomy have been described previously as well as in this study. Anterior-inclined osteotomy tends to result in the anterior translation of the proximal fragment. This may result in increased vertical vector force onto the patellofemoral joint, which further accelerates patellofemoral joint degeneration. Therefore, surgeons should attempt to perform parallel osteotomy or avoid anterior displacement of the proximal fragment if there is concern of anterior-inclined osteotomy.

[Effectiveness of medial open wedge high tibial osteotomy combined with posterior slope angle of tibial plateau correction in treatment of osteoarthritis of limited flexion knee with varus deformity]

Objective

To explore the short-term effectiveness of medial open wedge high tibial osteotomy (OWHTO) combined with posterior slope angle of tibial plateau correction to treat the osteoarthritis of limited flexion knee with varus deformity.

Methods

The data of 18 cases (18 knee) with osteoarthritis of limited flexion knee with varus deformity between January 2014 and July 2016 were analyzed retrospectively. There were 6 males and 12 females with an average age of 54.9 years (range, 48-64 years). There were 8 cases of left knee and 10 cases of right knee. The varus of knee ranged from 7.45 to 15.52° (mean, 10.63°). According to Kellgren-Lawrence grading standard, there were 4 cases of grade Ⅱ and 14 of grade Ⅲ. OWHTO was used to adjust the varus deformity, and the posterior slope angle of tibial plateau was adjusted to solve the limited flexion.

Results

The thickness of osteotomy was 10-19 mm (mean, 14.91 mm). The operation time was 1.2-2.0 hours (mean, 1.4 hours). All incisions healed by first intension. All patients were followed up 1.0-2.5 years, with an average of 1.5 years. At last follow-up, the range of knee flexion and Lysholm score, Hospital for Special Surgery (HSS) score, and International Knee Documentation Committee (IKDC) score were significantly higher than preoperative ones, showing significant differences ( P<0.05). X-ray films showed that the osteotomy healed at 3- 7 months (mean, 3.6 months) after operation. At last follow-up, the limb alignment by the relative position of tibial plateau and the posterior slope angle of tibial plateau were significantly improved, showing significant differences when compared with preoperative ones ( P<0.05).

Conclusion

The OWHTO combined with posterior slope angle of tibial plateau correction can significantly improve the range of flexion and functional score in short-term.

Biomechanical comparison of two different locking plates for open wedge high tibial osteotomy

BACKGROUND

The purpose of this study was to compare the mechanical stability of a relatively thin locking plate (FlexitSystem implant) with a relatively firm locking plate (TomoFix implant), both used for opening wedge high tibial osteotomy.

METHODS

Seven fresh frozen paired human cadaveric tibiae were used. The opening wedge high tibial osteotomies in the left tibiae were fixated with the FlexitSystem implant and in the right tibiae with the TomoFix implant. The tibiae were CT-scanned to determine the bone mineral density. Axial loading was applied in a cyclic fashion for 50,000 cycles. We compared throughout the loading history the relative motions between the proximal and distal tibia using roentgen stereophotogrammetry analysis at set intervals. Also the strength of the reconstructions was compared using a displacement-controlled compressive test until failure.

RESULTS

One pair (with the lowest bone mineral density) failed during the preparation of the osteotomy. The FlexitSystem implant displayed a similar stability compared to the TomoFix implant, with low translations (mean 2.16 ± 1.02 mm vs. 4.29 ± 5.66 mm) and rotations (mean 3.17 ± 2.04° vs. 4.30 ± 6.78°), which was not significant different. Although on average the FlexitSystem reconstructions were slightly stronger than the Tomofix reconstructions (mean 4867 ± 944 N vs. 4628 ± 1987 N), no significant (p = 0.71) differences between the two implants were found.

CONCLUSION

From a biomechanical point of view, the FlexitSystem implant is a suitable alternative to the TomoFix implant for a high tibial open wedge osteotomy.

Posteromedially placed plates with anterior staple reinforcement are not successful in decreasing tibial slope in opening-wedge proximal tibial osteotomy

PURPOSE

To document the effectiveness of a novel technique to decrease tibial slope in patients who underwent a proximal opening-wedge osteotomy with an anteriorly sloped plate placed in a posteromedial position. The hypothesis was that posteromedial placement of an anteriorly sloped osteotomy plate with an adjunctive anterior bone staple on the tibia would decrease, and maintain, the tibial slope correction at a minimum of 6 months following the osteotomy.

METHODS

All patients who underwent biplanar medial opening-wedge proximal tibial osteotomy with anterior staple augmentation to decrease sagittal plane tibial slope were included, and data were collected prospectively and reviewed retrospectively. Indications for decreasing tibial slope included medial compartment osteoarthritis with at least one of the following: ACL deficiency, posterior meniscus deficiency, or flexion contracture. Preoperative, immediate postoperative, and 6-month postoperative radiographs were reviewed.

RESULTS

Twenty-one patients (14 males and 7 females) were included in the study with a mean age of 36.5 years. Intrarater and interrater reliability of slope measurements were excellent at all time points (ICC ≥ 0.94, ICC ≥ 0.85). The osteotomy resulted in an average tibial slope decrease of 0.8 from preoperative (n.s.). At 6-month postoperative, average slope was not significantly different from time-zero postoperative slope (mean = +0.2°).

CONCLUSIONS

The most important finding of this study was that posteromedial placement of an anteriorly angled osteotomy plate augmented with an anterior staple during a biplanar medial opening-wedge proximal tibial osteotomy did not decrease sagittal plane tibial slope. Whether a staple was effective in maintaining tibial slope from time zero to 6 months postoperatively was unable to be assessed due to no significant change in tibial slope from the preoperative postoperative states. The results of this study note that current osteotomy plate designs and surgical techniques are not effective in decreasing sagittal plane tibial slope.

LEVEL OF EVIDENCE

IV.

Open-Wedge Valgus High Tibial Osteotomy Technique With Inverted L-Shaped Configuration

High tibial osteotomy (HTO) is a useful alternative in the treatment of symptomatic varus malalignment. However, among its drawbacks is the tendency to decrease patellar height and increase the posterior tibial slope. The increased tibial slope increases anterior cruciate ligament tension and may compromise its function. On the other hand, patella baja often causes anterior knee pain and, over time, may favor degeneration of the patellofemoral joint. The aim of this study is to describe a technical modification of the standard open-wedge HTO. It consists of a double inverted L-shaped cut, which includes the anterior tibial tuberosity in the proximal fragment, to avoid any alteration of patellar height and control the eventual increase of the posterior tibial slope.

Comparison of monoplanar versus biplanar medial opening-wedge high tibial osteotomy techniques for preventing lateral cortex fracture

PURPOSE

The purpose of this study was to investigate the mechanical strength of both monoplanar and biplanar medial opening-wedge high tibial osteotomy (MOWHTO) procedures and assess the risk of lateral cortex disruption for both techniques.

METHODS

Twelve synthetic tibia models with cortical shells were used as test models. Saw cuts for monoplanar MOWHTO and biplanar MOWHTO were generated on the test models in equal numbers (n = 6 for both groups). Wedge opening load and wedge gap distance were evaluated via compressive tests.

RESULTS

The mean gap distance just before the lateral cortex fracture in the monoplanar group was 14.7 ± 2.9 mm, which was significantly narrower than that in the biplanar group of 19.1 ± 2.0 mm (p = 0.015). The mean load just before the occurrence of lateral cortex fracture of 32.4 ± 3.2 N in the monoplanar osteotomy group was significantly lower than that in the biplanar osteotomy group of 111.8 ± 9.3 N (p = 0.009).

CONCLUSION

Performing a MOWHTO via the biplanar rather than the monoplanar technique allows larger-sized wedges to be opened with less risk of lateral cortical fracture. Thus, larger gaps can be opened and higher angle corrections can be achieved using the biplanar osteotomy procedure. From a clinical viewpoint, the biplanar osteotomy technique reduced the risk of lateral cortical hinge fracture during MOWHTO.

High tibial osteotomy in knee laxities: Concepts review and results

Patients with unstable, malaligned knees often present a challenging management scenario, and careful attention must be paid to the clinical history and examination to determine the priorities of treatment.

Isolated knee instability treated with ligament reconstruction and isolated knee malalignment treated with periarticular osteotomy have both been well studied in the past. More recently, the effects of high tibial osteotomy on knee instability have been studied.

Lateral closing-wedge high tibial osteotomy tends to reduce the posterior tibial slope, which has a stabilising effect on anterior tibial instability that occurs with ACL deficiency.

Medial opening-wedge high tibial osteotomy tends to increase the posterior tibia slope, which has a stabilising effect in posterior tibial instability that occurs with PCL deficiency.

Overall results from recent studies indicate that there is a role for combined ligament reconstruction and periarticular knee osteotomy.

The use of high tibial osteotomy has been able to extend the indication for ligament reconstruction which, when combined, may ultimately halt the evolution of arthritis and preserve their natural knee joint for a longer period of time.

Cite this article: Robin JG, Neyret P. High tibial osteotomy in knee laxities: Concepts review and results. EFORT Open Rev 2016;1:3-11. doi: 10.1302/2058-5241.1.000001.

Osteotomy configuration of the proximal wedge and analysis of the affecting factors in the medial open-wedge high tibial osteotomy

PURPOSE

The purposes of this study were (1) to confirm the disparity of the measured thickness at the lateral hinge between anterior-posterior (AP) radiograph and 3D CT image, (2) to evaluate the affecting factors, and (3) to evaluate the differences between uniplanar and biplanar osteotomies.

METHODS

From 2012 to 2014, a prospective comparative study was performed with 30 patients who received uniplanar osteotomy (group I) and 35 patients who received biplanar osteotomy (group II). For measurement of the proximal wedge, postoperative AP radiograph and 3D CT images were used. In the AP radiograph, medial and lateral bony bridge thicknesses were measured. In the 3D CT, the anterior and posterior images parallel to the coronal plane were selected for the evaluation. Coronal osteotomy slope was measured with the anterior image of the 3D CT scan. Sagittal osteotomy slope was measured with the sagittal section of the CT scan.

RESULTS

Differences between the lateral bony bridge thicknesses measured in AP radiograph and the posterolateral posterolateral bony bridge thicknesses measured in 3D CT were statistically significant in both groups. Negative correlation was observed in the biplanar osteotomy group. Differences of the sagittal osteotomy slope from the native tibial slope showed negative correlation in the biplanar osteotomy group.

CONCLUSION

Thickness of the posterolateral bony bridge was smaller compared to the observed thickness on the AP radiograph image that is routinely used for the follow-up. The thickness would be getting smaller if osteotomy is performed with an abrupt angle on the coronal plane and reverse slope on the sagittal plane. Therefore, osteotomy with abrupt angle on the coronal plane and reverse slope on the sagittal plane should be avoided for the proper thickness of the posterolateral bony bridge.

LEVEL OF EVIDENCE

III.

Three-dimensional relationships between secondary changes and selective osteotomy parameters for biplane medial open-wedge high tibial osteotomy

BACKGROUND

To assess the axial rotational change of distal tibia and posterior tibial slope (PTS) change after OWHTO in 3-D planes and to identify the causal relationship on the effect of variation in the posterior slope angle and rotational errors.

METHODS

A total of 21 patients (23 knees) underwent OWHTO and were evaluated with 3D-CT before and after surgery. Medial proximal tibial angle in the coronal plane, PTS in the sagittal plane, and rotational axis in axial plane were evaluated and compared between pre- and post-operative 3D models constructed by applying reverse-engineering software. As a selective osteotomy parameter, hinge axis and gap ratio were measured in the postoperative 3D models RESULTS: The increasing tendency of internal rotation of the distal tibia after OWHTO was positively related to hinge axis (β=0.730, p=0.001, R²=0.546) and gap ratio (β=-0.283, p=0.001, R²=0.520), which also showed statistically significant linear correlations to PTS changes after multivariate regression analysis that controlled for the rotational change of the distal tibia (hinge axis: β=0.443, p=0.006; gap ratio: β=0.144, p=0.017).

CONCLUSION

Hinge axis more posterolaterally was related to a greater increase in internal rotation after biplane medial open-wedge HTO, and hinge axis and gap ratio were significant predictors of PTS change after rotational change was controlled for. Hinge axis has to be considered an important independent variable for limiting unintended axial rotation change as well as PTS change as secondary.

CLINICAL RELEVANCE

The relationship of the hinge axis with the rotational change and its influence to PTS change, acknowledged from by-product of the statistical analysis, might provide a deeper understanding of HTO, and should have constitutional effects on the development of HTO procedures and implants.

Changes in coronal alignment of the ankle joint after high tibial osteotomy

PURPOSE

The purpose of this study was to investigate changes in coronal alignment of the ankle joint after HTO. Our hypothesis was that ankle joint orientation may become more parallel or less parallel to the ground after HTO, and this change may affect ankle symptoms.

METHODS

Eighty-six knees were retrospectively analysed after HTO for varus osteoarthritis. Preoperative and follow-up whole-leg radiographs were taken. The hip-knee-ankle (HKA) angle and medial proximal tibial angle (MPTA) were measured to evaluate coronal alignment of the knee. Tibial plafond inclination (TPI), talar inclination (TI), talar tilt (TT), and lateral distal tibial angle (LDTA) were measured to evaluate coronal alignment of the ankle. Patients were divided into two groups: those who exhibited a decrease in the absolute value of TPI and TI after HTO (group A) and those who exhibited an increase in the absolute value of TPI or TI after HTO (group B). Clinical outcomes of the knee and ankle were evaluated pre- and postoperatively.

RESULTS

Mean TPI and TI changed from 6.9° ± 3.6° and 8.0° ± 3.8° to 2.8° ± 3.1° and 3.9° ± 3.0° in group A (P < 0.001 for both) and from -1.3° ± 3.7° and 0.6° ± 4.5° to -6.0° ± 4.2° and -4.6° ± 5.9° in group B (P = 0.018 for both). VAS for ankle pain did not change significantly after HTO (n.s.) in group A, whereas those of group B increased significantly after HTO (P = 0.014).

CONCLUSION

Ankle joint orientation becomes more parallel or less parallel to the ground after HTO. Smaller preoperative HKA and LDTA result in a more valgus ankle joint orientation after HTO. Ankle symptoms were affected by coronal alignment changes of the ankle after HTO.

LEVEL OF EVIDENCE

III.

Multiobjective optimization of cartilage stress for non-invasive, patient-specific recommendations of high tibial osteotomy correction angle - a novel method to investigate alignment correction

Medial opening wedge high tibial osteotomy (MOWHTO) is a surgical procedure to treat knee osteoarthritis associated with varus deformity. However, the ideal final alignment of the Hip-Knee-Ankle (HKA) angle in the frontal plane, that maximizes procedural success and post-operative knee function, remains controversial. Therefore, the purpose of this study was to introduce a subject-specific modeling procedure in determining the biomechanical effects of MOWHTO alignment on tibiofemoral cartilage stress distribution. A 3D finite element knee model derived from magnetic resonance imaging of a healthy participant was manipulated in-silico to simulate a range of final HKA angles (i.e. 0.2°, 2.7°, 3.9° and 6.6° valgus). Loading and boundary conditions were assigned based on subject-specific kinematic and kinetic data from gait analysis. Multiobjective optimization was used to identify the final alignment that balanced compressive and shear forces between medial and lateral knee compartments. Peak stresses decreased in the medial and increased in the lateral compartment as the HKA was shifted into valgus, with balanced loading occurring at angles of 4.3° and 2.9° valgus for the femoral and tibial cartilage respectively. The concept introduced here provides a platform for non-invasive, patient-specific preoperative planning of the osteotomy for medial compartment knee osteoarthritis.

Changes in posterior tibial slope angle in patients undergoing open-wedge high tibial osteotomy for varus gonarthrosis

PURPOSE

In this study, postoperative changes in the posterior tibial slope angle and clinical outcomes following open-wedge high tibial osteotomy were evaluated.

METHODS

This study included 39 knees (18 left, 21 right) of 35 patients (three male, 32 female; median age, 53 years; age range 37-64 years) with symptomatic isolated medial joint osteoarthritis who underwent open-wedge high tibial osteotomy and fixation with a Puddu plate. The patients were clinically assessed according to the Lysholm knee score, a visual analogue pain scale, and a patient satisfaction questionnaire. Radiological assessment was made according to the changes in the posterior tibial slope angle and the correlation between these changes and clinical signs. The median follow-up period was 11 years (range 7-14 years).

RESULTS

Significant improvements were observed in the preoperative and postoperative clinical scores of the Lysholm knee scale, visual analogue pain scale, and patient satisfaction questionnaire (p < 0.05). Radiological assessment showed that the posterior tibial slope angle was significantly higher during the postoperative and follow-up periods (p  0.05). There was no correlation between the postoperative Lysholm scores and the increase in the posterior tibial slope angle (p = n.s.).

CONCLUSIONS

We conclude that both the conventional Puddu plate design and its anteromedial plate placement are what increase the tibial slope after an opening-wedge proximal tibial osteotomy. Therefore, current new plate design may help preserve the posterior tibial slope angle.

LEVEL OF EVIDENCE

IV.

Computer-assisted navigation decreases the change in the tibial posterior slope angle after closed-wedge high tibial osteotomy

PURPOSE

The purpose of the present study was to compare the change in tibial posterior slope angle (PSA) between patients treated via computer-assisted and conventional closed-wedge high tibial osteotomy (CWHTO). It was hypothesized that a decrease in the PSA would be less in the computer-assisted group than in the conventional group.

METHODS

Data on a total of 75 computer-assisted CWHTOs (60 patients) and 75 conventional CWHTOs (49 patients) were retrospectively compared using matched pair analysis. The pre- and postoperative mechanical axis (MA) and the PSA were radiographically evaluated. The parallel angle was defined as the angle between the joint line and the osteotomy surface. The data were compared between the two groups.

RESULTS

The postoperative radiographic MA averaged 1.3° ± 2.6° valgus in the computer-assisted group and 0.3° ± 3.1° varus in the conventional group. The change in PSA averaged -0.8° ± 0.9° in the computer-assisted group and -4.0° ± 2.2° in the conventional group. The parallel angle averaged 0.2° ± 3.0° in the computer-assisted group and 6.2° ± 5.3° in the conventional group.

CONCLUSION

Computer-assisted CWHTO using four guide pins could avoid inadvertent change in the PSA. The navigation can be used in anticipation of decreasing the risk of change in the PSA in CWHTO, especially in patients whose preoperative PSA is small. The special attention should be paid to locate the hinge axis acutely and to make the parallel proximal and distal osteotomy surfaces during CWHTO.

LEVEL OF EVIDENCE

III.

The biplanar open wedge high tibial osteotomy preserving the tibial tubercle

BACKGROUND

High tibial osteotomy (HTO) is a treatment option for relatively young patients with isolated medial compartment arthritis of the knee. Medial open wedge osteotomies allow easier control of correction, but can lead to patella infera as a result of distalization of the tibial tubercle. This retrospective study reports results of a biplanar tibial tubercle preserving HTO, designed to preserve patellar height.

METHODS

The study is a retrospective analysis of 12 consecutive patients (11 men, 1 woman) average age 39.6 years who underwent the procedure between 2009 and 2012. A biplanar open wedge tibial osteotomy was performed and stabilised with a medial locking plate. Patients were allowed full weight bearing at 6 weeks. Preoperative and postoperative function was recorded on the Oxford knee score, Lysholm score and Tegner activity scale. Minimum follow up was 26 months.

RESULTS

All patients had healing of the osteotomy with no delayed union. Eleven patients reported improvement in symptoms with an average preoperative Oxford score of 26 and postoperative score of 39 out of 48. The Lysholm score improved from 58 to 72 out of 100. There was one point improvement in Tegner activity scale. There was no statistical difference in patellar height before and one year after surgery. The correction in varus averaged 8.3°.

CONCLUSION

The biplanar High tibial Osteotomy allows preservation of patellar height, while achieving desired varus correction.

Usefulness of long tibial axis to measure medial tibial slope for opening wedge high tibial osteotomy

PURPOSE

To assess which tibial slope measurements on knee, whole leg radiographs and three-dimensional reconstructed computed tomography (CT) were useful in clinical practice before and after opening wedge high tibial osteotomy.

METHODS

Medial and lateral tibial slopes on knee, whole leg radiographs and three-dimensional reconstructed CT were measured in 50 patients with knee osteoarthritis. To investigate the intraobserver reproducibility and interobserver reliability for each medial and lateral tibial slope on knee, whole leg radiographs and CT, the measurements were repeated twice by two observers. The statistical differences between the medial and lateral tibial slopes obtained by the three methods, and the differences and correlation coefficients for the medial and lateral tibial slopes between knee or whole leg radiographs and CT were calculated.

RESULTS

The reproducibility and reliability of medial and lateral tibial slopes on CT were superior to those on whole leg or knee radiographs. The medial and lateral tibial slopes on whole leg radiographs had better reproducibility and reliability than those on knee radiographs. The mean medial tibial slopes on knee, whole leg radiographs and CT were 9.3 ± 3.4°, 12.3 ± 4.3° and 11.0 ± 3.9°, respectively. The mean lateral tibial slopes were 7.9 ± 3.1°, 9.6 ± 3.6° and 9.3 ± 2.9°, respectively. The medial tibial slopes on knee, whole leg radiographs and CT were significantly higher than the lateral tibial slopes (p < 0.01 for all).

CONCLUSIONS

Tibial slope measurements using CT required time and specialized software. Therefore, measurements of the medial tibial slope using the long tibial axis on whole leg radiographs were more reproducible and reliable and could be an alternative to CT in clinical practice.

LEVEL OF EVIDENCE

III.

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.

Better clinical results after closed- compared to open-wedge high tibial osteotomy in patients with medial knee osteoarthritis and varus leg alignment

PURPOSE

Studies comparing mid- or long-term outcomes of open- and closed-wedge high tibial osteotomy are limited. Here, the midterm survival rate and clinical and radiographic outcomes were compared for these two techniques. The study hypothesis, based on short-term follow-up, was that after midterm follow-up, the two techniques would not differ.

METHODS

A prospective follow-up study was conducted for a previously reported randomized controlled trial of an original 50 patients (25 open-wedge osteotomy and 25 closed-wedge osteotomy) with medial knee osteoarthritis and a varus leg alignment. We analyzed patients without knee arthroplasty (mean age 48.7 years, SD 8.0) for clinical and radiographic follow-up.

RESULTS

Five patients in each group had undergone conversion to a total knee arthroplasty or unicompartmental knee arthroplasty, leaving 19 patients for analysis in each group. At 7.9 years of follow-up (range 7-9 years), survival did not differ significantly between groups (open-wedge group 81.3% [95% confidence interval (CI) 75.2-100], closed-wedge group 82.0% [95% CI 66.7-100]). At final follow-up, total Dutch Western Ontario and McMaster Universities Arthritis (WOMAC), Knee Society Score, and visual analog scale (VAS) pain did not differ between groups. However, the results were significantly better in the closed-wedge group for VAS satisfaction and WOMAC pain and stiffness compared to the open-wedge group. Radiographic evaluation did not differ between groups for any outcome at final follow-up.

CONCLUSION

After a mean follow-up of 7.9 years, patients undergoing a closed-wedge osteotomy had favorable clinical results compared to those who underwent an open-wedge osteotomy.

LEVEL OF EVIDENCE

II.

Unintended Rotational Changes of the Distal Tibia After Biplane Medial Open-Wedge High Tibial Osteotomy

This study involved 35 knees undergoing biplane medial open-wedge high tibial osteotomy (OWHTO) to assess the axial rotation of the distal tibia. The distal tibiae were internally rotated by 3.0° ± 7.1° after OWHTO. The opening width showed a Pearson correlation coefficient of -0.743 (P < .001), and the tuberosity osteotomy angle showed that of -0.678 (P < .001) with distal tibial rotation. However, changes in hip-knee-ankle angle, medial proximal tibial angle, and posterior tibial slope were not significantly correlated with the change in distal tibial rotation. In conclusion, there was an unintended tendency of increasing internal rotation of the distal tibia after biplane medial OWHTO, and this tendency was positively related to the opening width and tuberosity osteotomy angle.

Effect of open wedge high tibial osteotomy on the lateral tibiofemoral compartment in sheep. Part III: analysis of the microstructure of the subchondral bone and correlations with the articular cartilage and meniscus

PURPOSE

First, to evaluate whether medial open wedge high tibial osteotomy (HTO) induces alterations of the microstructure of the lateral tibial subchondral bone plate of sheep. Second, to test the hypothesis that specific correlations exist between topographical structural alterations of the subchondral bone, the cartilage and the lateral meniscus.

METHODS

Three experimental groups received biplanar osteotomies of the right proximal tibiae: (a) closing wedge HTO (4.5° of tibial varus), (b) opening wedge HTO (4.5° tibial valgus; standard correction) and (c) opening wedge HTO (9.5° of valgus; overcorrection), each of which was compared to the non-osteotomised contralateral proximal tibiae. After 6 months, subchondral bone structure indices were measured by computed tomography. Correlations between the subchondral bone, the articular cartilage and the lateral meniscus were determined.

RESULTS

Increased loading by valgus overcorrection led to an enlarged specific bone surface (BS/BV) in the subarticular spongiosa compared with unloading by varisation. The subchondral bone plate was 3.9-fold thicker in the central region of the lateral tibial plateau than in the submeniscal periphery. Its thickness in the central region significantly correlated with the thickness of the articular cartilage. In the submeniscal region, such correlation did not exist. In general, a higher degree of osteoarthritis (OA) correlated with alterations of the subchondral bone plate microstructure. OA of the submeniscal articular cartilage also correlated with worse matrix staining of the lateral meniscus.

CONCLUSION

Osteoarthritis changes are associated with alterations of the subchondral bone plate microstructure. Specific topographical relationships exist in the central region between the articular cartilage and subchondral bone plate thickness, and in the submeniscal periphery between and the articular cartilage and lateral meniscus. From a clinical perspective, the combined follow-up data from this and the previous two investigations suggest that open wedge valgus HTO is a safe procedure for the lateral compartment to manage medial osteoarthritis of the knee with varus malalignment in the short term.

Factors influencing posterior tibial slope and tibial rotation in opening wedge high tibial osteotomy

PURPOSE

Opening wedge high tibial osteotomy (HTO) is an accepted treatment option for medial compartment knee osteoarthritis with associated varus lower limb axis in younger, more active patients. A concern with the use of this technique is that posterior tibial slope (PTS) and tibial rotation can be altered. We hypothesized that there is a tendency to increase the PTS and internal rotation of the distal tibia during the procedure and that certain intra-operative parameters may influence the amount of change that can be expected.

METHODS

A cadaveric model and surgical navigation system were used to evaluate the influence of certain intra-operative factors of the degree of PTS and tibial rotation change observed during medial opening HTO. Parameters evaluated included: degree of osteotomy opening, knee flexion angle, location of limb support (thigh versus foot), performance of a posteromedial release, the status of the lateral cortical hinge, and the degree of osteoarthritis present in the knee.

RESULTS

Combining measurements of all specimens and parameters, a mean PTS increase of 2.7° ± 3.9° and a mean tibial internal rotation of 1.5° ± 2.9° were observed. Clinically, significant changes in tibial slope (>2°) occurred in 50.4 % of corrections, while significant changes in tibial rotation (>5°) occurred in only 11.9 % of corrections. Patients with significant osteoarthritis and concomitant flexion contracture, cases where large corrections were required, and procedures in which the lateral cortical hinge was disrupted were associated with increased PTS change. The other factors evaluated did not exert a significant influence of the degree of PTS change observed.

CONCLUSIONS

Surgeons should be vigilant for possible PTS change, particularly in high-risk situations as outlined above. Routine use of an intra-operative measure of PTS is recommended to avoid inadvertent slope change.

Effect of high tibial osteotomy on joint loading in symptomatic patients with varus aligned knees: a study using SPECT/CT

PURPOSE

The purpose was to prospectively evaluate the outcome, in particular the SPECT/CT bone tracer uptake (BTU) after high tibial osteotomy (HTO) due to symptomatic varus malalignment. It was the hypothesis that the BTU after HTO decreases in the medial compartment, clinical outcome and the degree of correction correlates with BTU and asymptomatic patients after HTO reveals a significantly decreased BTU in the medial subchondral areas.

METHODS

Twenty-two consecutive patients with 23 knees undergoing medial opening-wedge HTO for medial compartment overloading were assessed pre- and postoperatively (12 and/or 24 months) using Tc-99m-HDP-SPECT/CT including our 4D-SPECT/CT protocol. BTU was quantified and localized to specific biomechanically relevant joint areas. Maximum absolute and relative values (mean ± standard deviation, median and range) for each area were recorded. Pre- and postoperative mechanical alignment was measured. At 24 months after HTO, the WOMAC score was used.

RESULTS

A significant decrease of BTU in the medial subchondral zones after HTO was found (preoperatively to 12 and 24 months postoperatively, p < 0.01). BTU normalized in all asymptomatic patients within 24 months. This decrease was partly seen in the lateral compartments, but significantly higher in the medial compartments (p < 0.0001). A significant increase of the BTU was noted in zones directly adjacent to the plate or within the osteotomy zone (p < 0.01). Decreased BTU was observed in osteotomy zones at 24 months postoperatively following higher uptake values at 12 months postoperatively. The average valgus correction of the tibiofemoral angle was 5.9° ± 2.8°. Less stiffness correlated significantly with a higher decrease in BTU (p < 0.05). Higher postoperative BTU significantly correlated with more pain (p < 0.05). No statistical significant associations between BTU and alignment correction were found.

CONCLUSION

In patients with medial compartment, overloading due to varus malalignment HTO led to a significant decrease in BTU in the medial joint compartments. SPECT/CT BTU patterns and intensity in these patients pre- to 12 and 24 months postoperatively were seen. These correlated significantly with pain and stiffness. Hence, SPECT/CT could be used for assessment of adequate correction and healing after HTO. SPECT/CT could be further used to identify the optimal individualized correction for each patient and clinical scenario.

CLINICAL EVIDENCE

Diagnostic prospective study, Level II.

The Effect of Hinge Position on Posterior Tibial Slope in Medial Open-Wedge High Tibial Osteotomy

PURPOSE

To evaluate whether hinge position affects the change in posterior tibial slope in medial open-wedge high tibial osteotomy (HTO).

METHODS

We retrospectively evaluated 19 knees from 17 patients who underwent medial open-wedge HTO by 3-dimensional computed tomography scan before and after surgery. A 3-dimensional image model was constructed by applying reverse-engineering software to the computed tomography DICOM (Digital Imaging and Communications in Medicine) files. The hinge axis (i.e., the position of the hinge compared with the anteroposterior axis on an axial view), posterior tibial slope, medial-proximal tibial angle, and gap ratio (i.e., the ratio of anterior gap to posterior gap in the opened wedge) were measured.

RESULTS

The mean hinge axis was 4.92° ± 3.86°. Posterior tibial slope increased from 7.29° ± 2.56° preoperatively to 10.48° ± 3.01° postoperatively (P = .001). The mean medial-proximal tibial angle was 85.96° ± 1.97° preoperatively and 93.13° ± 3.17° postoperatively (P = .001). The mean gap ratio was 62.48% ± 7.26%. Linear regression analysis determined that the hinge axis (P = .0001) was a significant factor changing posterior tibial slope.

CONCLUSIONS

Hinge position affected the change in posterior tibial slope in medial open-wedge HTO; in particular, a posterolateral hinge position led to an increase in posterior tibial slope.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Comparative analysis of osteotomy accuracy between the conventional and devised technique using a protective cutting system in medial open-wedge high tibial osteotomy

INTRODUCTION

Open-wedge high tibial osteotomy (OWHTO) is associated with potential intraoperative problems. For prevention of these problems, we thought that some surgical improvements were required and devised a protective cutting system (PCS). The purposes of this study were (1) to test our devised protective cutting system and (2) compare its accuracy in osteotomy to that of a conventional technique.

MATERIALS AND METHODS

A comparative study was performed with 19 patients who underwent OWHTO with PCS (group I) and 16 patients who underwent OWHTO using a conventional technique (group II). For the evaluation of osteotomy accuracy, osteotomy lines of the anterior and posterior cortex were analyzed in the 3D surface models [Total (T), Osteotomy (O), Ratio (O/T), Effective osteotomy (E), Deviation direction (DD), and length (DL)]. Analysis of changes of the medial and lateral tibial slope was performed independently, and intraoperative complications were also analyzed.

RESULTS

In the osteotomy line of the anterior aspect, O-anterior and Ratio (O- and T-anterior) showed statistical significance, and a larger osteotomy was observed in group II (p = 0.02 and 0.01, respectively). In the osteotomy line of the posterior aspect, Ratio (O- and T-posterior) and E-posterior showed statistical significance (p = 0.01 and 0.01, respectively). In the comparison between the change of the medial and lateral tibial slope, statistical significance was observed in both groups, and the medial tibial slope showed a larger increase than that of the lateral side (p = < 0.01 and <0.01, respectively). There were more intraoperative complications such as fracture and deviation of the osteotomy plane in group II, and this was more prominent at the posterior aspect.

CONCLUSIONS

OWHTO with PCS could improve the accuracy of osteotomies, especially those of the posterior cortex of the proximal tibia, thus resulting in a reduction of intraoperative complications.