Smoking and unstable hinge fractures cause delayed gap filling irrespective of early weight bearing after open wedge osteotomy

Ten-year minimal follow-up of lateral opening wedge distal femoral osteotomy for lateral femorotibial osteoarthritis: Good survivorship and high patient satisfaction

PURPOSE

This study aimed (1) to determine complications and survival rates of lateral opening wedge distal femoral osteotomy (LOW-DFO) in the long term, (2) to assess their clinical outcomes in the long term and (3) to identify risk factors of failure.

METHODS

Between 1991 and 2011, 62 LOW-DFOs were performed in the same department. Inclusion criteria were all isolated LOW-DFO performed for isolated lateral tibiofemoral osteoarthritis and valgus malalignment, with a minimum 10-year follow-up. Thirty-eight patients were included, with a mean age of 48 ± 9 years. All patients had clinical and radiological assessments. The survival curves were calculated based on the following endpoints: unicompartmental or total knee arthroplasty.

RESULTS

The mean follow-up was 15.2 ± 4.4 [10-29] years. The mean preoperative mechanical FemoroTibial Axis (mFTA) was 188.8° ± 3.2° [184°-197°], primarily due to femur deformity (mean lateral distal femoral axis [LDFA] 83.2° ± 2.8°). Bone union was achieved in 89.5% of patients (n = 34) at a mean delay of 6.5 ± 6.7 months. The complication rate was 26% (five stiffness, one nonunion, three secondary displacements and one deep vein thrombosis). Nine revision surgeries (24%) were recorded. Survival rates at 5 and 10 years were 92.1% and 78.9%, respectively. The mean delay between DFO and total knee arthroplasty (TKA) was 11.6 ± 5.7 [1-27] years. Nineteen patients (50%) were free of TKA at the last follow-up. KSS scores were improved significantly. Return to sports was obtained in 92% of cases (n = 35), with a mean delay of 11 ± 8 months. Seventy-four per cent of patients were satisfied or very satisfied with the surgery. Eighty-four per cent would be willing to undergo the surgery again. Older age (p = 0.032) was a significant risk factor for TKA conversion.

CONCLUSION

LOW-DFO is an efficient procedure to manage lateral knee osteoarthritis in young patients with valgus deformity, with a good survival rate at 10 years and high patient satisfaction.

LEVEL OF EVIDENCE

Level III.

Fixation of Takeuchi Type II/III lateral hinge fractures provides favourable stability of a medial open wedge high tibial osteotomy-A biomechanical study

PURPOSE

To investigate the biomechanical consequences of osteosynthesis of lateral hinge fractures (LHFs) in medial open wedge high tibial osteotomy (MOWHTO).

METHODS

Sixteen fresh-frozen human cadaveric proximal tibiae underwent MOWHTO fixed with an ipsilateral locking compression plate. The specimens were assigned to two clusters simulating LHFs according to the Takeuchi classification: (1) Type II fracture; and (2) Type III fracture. The following conditions were serially tested: (1) intact hinge; (2) fractured hinge; (3) screw fixation of the LHF; (4) staple fixation of the LHF; and (5) locking T-plate fixation of the LHF. Each specimen was subjected to 10 cycles of axial compression load (720 N; 36 N/s), and internal and external rotational loads (10 N m; 1 N m/s), while capturing the interfragmentary movements via motion tracking.

RESULTS

In Takeuchi Type II fractures, osteosynthesis of the fractured hinge with staples or a plate significantly reduced fracture site displacement (p < 0.05) and significantly increased construct stiffness (p < 0.05) under axial and torsional loading, while only the plate restored intact torsional displacement (n.s.). For Takeuchi Type III fractures, both screw and plate fixation significantly reduced fracture site displacement (p < 0.05) and significantly increased construct stiffness (p < 0.05) under axial and torsional loading. Both techniques restored torsional stiffness in each rotational direction and torsional displacement in internal rotation (n.s.).

CONCLUSION

Additional plate fixation of Takeuchi Type II fractures was the construct with the highest stiffness, restoring the axial and torsional stability to a MOWHTO with an intact hinge. Screw and plate fixation of Takeuchi Type III fractures provided equivalent stability and restored the torsional and axial stability of the MOWHTO. In case of a Takeuchi Type II or III fracture, surgeons should consider additional plate or screw osteosynthesis of the fractured hinge to best restore the stability of the MOWHTO, which may potentially reduce the risk of loss of correction and impaired bone healing.

LEVEL OF EVIDENCE

There is no level of evidence as this study was an experimental laboratory study.

An increased medial proximal tibial angle of greater than 95 degrees after opening wedge high tibial osteotomy is not associated with deterioration of minimum 10-year clinical outcomes

PURPOSE

The purpose of this study was to assess whether an excessively increased medial proximal tibial angle (MPTA) resulted in the deterioration of long-term clinical outcomes after opening wedge high tibial osteotomy (OWHTO) for patients with knee osteoarthritis (OA).

METHODS

A total of 69 OA knees that underwent OWHTO, with follow-up for a minimum of 10 years, were retrospectively reviewed. The knee and function scores of the Knee Society Score were assessed separately, and cases with a score decline greater than or equal to the minimal clinically important difference from postoperative 1 to 10 years were defined as showing clinical deterioration. Cartilage status was assessed with arthroscopy at the time of osteotomy (first-look) and plate removal (second-look) according to the International Cartilage Repair Society grading system. The outcomes were compared between knees with MPTA ≤ 95° (n = 27) and MPTA > 95° (n = 42).

RESULTS

The mean knee and function scores at postoperative 10 years in MPTA ≤ 95° knees (86.8 ± 9.6 and 90.4 ± 13.1) were not significantly different from those in MPTA > 95° knees (85.8 ± 11.5 and 86.9 ± 14.2). The rate of clinical deterioration in knee and function scores was not significantly different between MPTA ≤ 95° knees (26% and 26%) and MPTA > 95° knees (21% and 36%). No significant differences were found between the MPTA ≤ 95° and MPTA > 95° groups in the cartilage status of all compartments at both first-look and second-look (postoperative 21 months) arthroscopies.

CONCLUSIONS

Increased MPTA > 95° after OWHTO is not associated with deterioration of minimum 10-year clinical outcomes.

Finite element analysis confirms the optimal apex position in medial opening wedge high tibial osteotomy to avoid lateral hinge fracture

Purpose

Lateral hinge fracture is a significant complication of medial opening wedge high tibial osteotomy. While fracture risk is closely associated with the osteotomy apex position, the optimum position remains variable within the literature. Our hypothesis is that stresses at the osteotomy apex predicted by finite element analysis can be used to identify an apex position which minimises intra and postoperative fracture risks.

Methods

A finite element model was studied to investigate the effect of varying the hinge position on fracture risk and severity for a given bone geometry; variables analysed included stress, strain and micromotion levels. Nine further knee models were studied to assess the variability between patients' bone properties and examine the effect of apex location on strains.

Results

Lateral hinge width and height significantly influence intra-operative stress, strain, and fracture risk, while hinge width predominately determines postoperative stability. Wider hinges improve postoperative stability, but increase the likelihood of intra-articular fractures. Aiming the apex at the fibular head height minimises strain. The osteotomy apex should be located such that the hinge width is equal to 13% of the medial-lateral width to minimise apex stress and fracture risk while preserving sufficient bone at the hinge for stability. The height of the apex from the tibial plateau should maintain a minimum value of 16% of the medial-lateral width to avoid intra-articular fracture, with the apex below the fibula head if necessary. The size of the tibia does not alter the optimal location, making our findings applicable across all tibia sizes.

Conclusions

Our study has investigated and verified a proposed optimal apex position, based upon fracture risk prediction and micromotion at the osteotomy apex. This is clinically useful due to the potential use of the apex point on preoperative 2D radiographs when planning surgery.

Level of Evidence

Not applicable.

Evaluating the Effectiveness of a Structural Allograft in Medial Open Wedge High Tibial Osteotomy in Patients With and Without a Lateral Hinge Fracture

Background

A lateral hinge fracture is a common complication in medial open wedge high tibial osteotomy (MOWHTO) and is associated with delayed union or nonunion. A comparison of outcomes between patients with or without a lateral hinge fracture after MOWHTO with a structural allograft has not been investigated.

Purpose

To validate the outcomes of MOWHTO with a structural allograft, especially in the presence of a lateral hinge fracture.

Study Design

Case series; Level of evidence, 4.

Methods

We conducted a single-surgeon cohort study at a tertiary referral hospital between April 2017 and August 2022 and included patients who had undergone MOWHTO with a structural allograft for isolated medial compartment osteoarthritis with genu varum. We compared the incidence of delayed union or nonunion events and functional scores between patients with a lateral hinge fracture and those without using the Fisher exact test and independent t test.

Results

A total of 88 MOWHTO procedures (77 patients) were analyzed. The overall incidence of lateral hinge fractures was 29.5% (n = 26), including type I (n = 20 [22.7%]) and type II (n = 6 [6.8%]). Notably, 42.3% (n = 11) of these fractures had not been detected intraoperatively but during the follow-up visits. The overall Knee Society Score (KSS), Knee Society Score-Function (KSS-F), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were 90.0 ± 10.0, 93.4 ± 10.8, and 93.8 ± 7.1 points, respectively. None of the patients had delayed union or nonunion, and none underwent a reoperation because of bony union problems. The functional scores (KSS, KSS-F, and WOMAC) were not different between patients who had a lateral hinge fracture and those who did not (P > .05).

Conclusion

The routine use of a structural allograft was associated with satisfactory outcomes after MOWHTO, regardless of whether there was a lateral hinge fracture.

Radiographic Assessment of Bone Union in Proximal Tibia and Distal Femur Osteotomies: A Systematic Review

Background

Osteotomies around the knee are a well-established treatment option for early and moderate unicompartmental osteoarthritis combined with a lower extremity malalignment. Moreover, osteotomies are often combined with cartilage treatment. Current image-based bone union assessments lack an accepted definition despite widespread use in research and clinical settings. The aim of this systematic review was to identify definitions and classification systems for bone union on radiographs after a proximal tibia or distal femur osteotomy.

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we systematically searched MEDLINE and Embase database, applying specific inclusion and exclusion criteria. Two independent reviewers screened abstracts and full-texts. The modified Cochrane Risk of Bias Tool and Risk of Bias in Nonrandomized Studies of Interventions tool were used. Data extraction included study characteristics, imaging modality, bone union definition, classification systems, assessment of gap fillers, use of modifiers, and osteotomy type.

Results

Of the 1,180 screened titles and abstracts, 105 studies were included, with the majority (69 studies [65.7%]) using a retrospective design. Fifty-five studies (52.4%) defined bone union based on one or more criteria, while 50 studies (47.6%) used a classification system. There were 13 different criteria for bone union and 9 different classification systems. Interestingly, none of the classification systems incorporated negative criteria, such as hardware failure. Notably, 137 studies (49.1%) described bone union as either a primary or secondary outcome but do not describe a system for assessing bone union.

Conclusion

This systematic review highlights the lack of consensus in the literature in defining bone union after a proximal tibia or distal femur osteotomy, revealing many criteria and different classifications. None of the classification systems were applicable to osteotomies with and without gap filler. This systematic review shows the need for a straightforward, reproducible, and accurate method to assess bone union after a proximal tibia or distal femur osteotomy.

Level of Evidence

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

Gap Volume Based on Computed Tomography Measurement Is a Strong Risk Factor for Delayed Gap Healing After Open-Wedge High Tibial Osteotomy

PURPOSE

To identify factors that affect delayed gap healing after open-wedge high tibial osteotomy (OWHTO) and to determine whether large gap volume is a predictor of delayed gap healing.

METHODS

This retrospective study analyzed biplane OWHTO performed between 2019 and 2023 for knee osteoarthritis or osteonecrosis. The minimum follow-up period was 1 year. Delayed gap healing was defined when the medial half of the osteotomy gap area had not reached the consolidation phase by 6 months after surgery based on anteroposterior knee radiographs. Gap volume was calculated from computed tomography images. Logistic regression was performed using body height, smoking, correction angle, hinge fracture, flange thickness, and gap volume. A gap volume cutoff value for delayed gap healing was determined with receiver operating characteristic curve analysis. Gap volume was predicted with multiple linear regression.

RESULTS

There were 80 knees in 71 patients (36 men and 44 women). The mean gap volume was 7.6 cm3. Gap healing rates at 3, 6, 9, and 12 months after surgery were 26%, 65%, 89%, and 100%, respectively. There were 25 knees with delayed gap healing. Male sex was not a significant risk factor when adjusted for body height. Multivariate logistic regression revealed that only larger gap volume was a significant risk factor (odds ratio, 1.45; P = .006). The gap volume cutoff value was 7.6 cm3, with an area under the curve of 0.74. Tall body height and a large correction angle (both P < .001) were associated with a significantly larger gap volume (R2 = 0.73).

CONCLUSIONS

Large gap volume is the most important risk factor for delayed gap healing after OWHTO. Gap volume can be predicted based on body height and correction angle. When OWHTO with substantial correction is planned for tall men, surgeons should be aware of possibly delayed gap healing.

LEVEL OF EVIDENCE

Level IV, retrospective case-control study.

Equal rates of bone healing and reduced surgical time with iliac crest allograft compared to autograft in medial opening wedge high tibial osteotomy: a randomized controlled clinical trial

INTRODUCTION

Iliac crest autograft is frequently used to fill in bone defects after osteotomies. Nonetheless, surgery for bone autograft procurement is associated with morbidity and pain at the donor site. Alternatives to it have been explored, but there is no consensus to guide their application as a routine practice in several orthopedic procedures. Thus, this study was designed to compare the efficacy and safety between iliac crest autograft and allograft in medial opening wedge high tibial osteotomy.

MATERIALS AND METHODS

Forty-seven patients with a symptomatic unilateral genu varum and an indication for high tibial osteotomy were randomly assigned to receive either autograft or allograft to fill the osteotomy site. Operative time, bone healing, and complication rates (delayed union, nonunion, superficial and deep infection, loss of correction, and hardware failure) were recorded after a one-year follow-up. Data were expressed as Mean ± Standard Deviation and considered statistically significant when p < 0.05.

RESULTS

The time to radiologic union was similar between both groups (Allograft: 2.38 ± 0.97 months vs. Autograft: 2.45 ± 0.91 months; p = 0.79). Complication rates were also similar in both groups, with one infection in the allograft group and two in the autograft group, two delayed unions in the allograft group, and three in the autograft group. The operative time differed by 11 min between the groups, being lower in the allograft group (Allograft: 65.4 ± 15.1 min vs. Autograft: 76.3 ± 15.2 min; p = 0.02).

CONCLUSION

Iliac crest allografts can be safely and effectively used in medial opening wedge high tibial osteotomy as it promotes the same rates of bone union as those achieved by autologous grafts, with the benefits of a shorter operative time.

TRIAL REGISTRATION NUMBER

U1111-1280-0637 1 December 2022, retrospectively registered.

Implant Removal After Medial Opening Wedge High Tibial Osteotomy Provides Implant-Related Pain Relief and Functional Improvement

PURPOSE

To investigate the incidence of implant-related pain after medial opening wedge high tibial osteotomy (MOWHTO) using a locking plate, to determine whether implant removal provides pain relief and functional improvement, and to evaluate bone healing and loss of correction after implant removal.

METHODS

Between March 2014 and September 2017, MOWHTO was performed without bone graft. The inclusion criteria were patients who underwent implant removal after MOWHTO and were followed up for a minimum of 2 years. Patients were evaluated for implant removal 1 and 2 years after surgery. Clinical and functional evaluations were conducted to investigate implant-related pain using the visual analog scale, Lysholm score, and Tegner score. The radiographic indices measured were the gap-filling rate, weightbearing line (WBL) ratio, hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), and posterior tibial slope angle (PTSA).

RESULTS

A total of 55 patients were enrolled. Fifty-one (92.7%) patients experienced implant-related pain prior to implant removal, with 43 and 8 patients reporting mild pain and moderate pain, respectively. At 1 and 2 years after implant removal, mild pain occurred in 6 (10.9%) and 5 (9.1%) patients, respectively. The remaining patients reported no implant-related pain. Prior to implant removal and 1 year after implant removal, the Lysholm score improved from 77.0 ± 5.6 to 86.8 ± 5.7 (P < .001), and the Tegner score improved from 3.3 ± 1.2 to 3.9 ± 1.3 (P < .001). The mean gap-filling rate was 84.4% ± 9.6% at implant removal, and it significantly increased to 93.7% ± 5.4% and 97.4% ± 2.6% at 1 and 2 years after implant removal, respectively (P < .001). For the WBL ratio, HKAA, MPTA, and PTSA, no statistically significant differences were found after implant removal.

CONCLUSIONS

The incidence of implant-related pain after MOWHTO using the medial proximal tibial locking plate was high. Implant removal provides pain relief and functional improvement (met minimal clinically important differences). Even after implant removal, bone healing progressed gradually without a loss of correction in all patients.

LEVEL OF EVIDENCE

Level IV, case series.

A systematic approach to managing complications after proximal tibial osteotomies of the knee

Proximal tibial osteotomy (PTO) is an effective procedure for active and young adult patients with symptomatic unicompartmental osteoarthritis and malalignment. They were considered technically demanding and prone to various complications related to the surgical technique, biomechanical or biological origin. Among the most important are hinge fractures and delayed or non-healing, neurovascular complications, loss of correction, implant-related problems, patellofemoral complaints, biological complications and changes in limb length. Being aware of these problems can help minimizing their prevalence and improve the results of the procedure.The aim of this narrative review is to discuss the potential complications that may occur during and after proximal tibial osteotomies, their origin and ways to prevent them.

The effect of smoking on union rates following corrective osteotomies around the knee: A systematic review and meta-analysis

BACKGROUND

Distal femur osteotomies (DFO) and high tibial osteotomies (HTO), are well-established treatment options for joint preservation in active patients with uni-compartmental osteoarthritis. Optimal outcomes are contingent on adequate preoperative evaluation of patient-specific factors. This systematic review and meta-analysis aims to explore the difference in union rates between smokers and non-smokers following corrective osteotomies around the knee.

METHODS

A systematic search of the MEDLINE and EMBASE databases was performed in accordance with the PRISMA guidelines to identify studies reporting smoking status in adults who developed delayed and/or non-union following HTO or DFO. Studies were pooled using a random effect model [Review Manager (RevMan) software, V.5.4] and heterogeneity was estimated using I2.

RESULTS

Data for meta-analysis was available for 1,406 osteotomies from 10 studies, performed in patients with mean age ranging from 38-54 years, and 65% were male. The union rate among non-smokers was 97.3% (1100/1131) compared with 89.5% (246/275) among smokers; OR 4.59 [95% CI 1.99 to 10.62], p-value < 0.001. Subgroup analysis revealed that the risk of non-union in smokers after opening wedge osteotomy was almost double (OR 4.8) that of closing wedge osteotomies (OR 2.9).

CONCLUSION

Smoking increases the risk of non-union during elective knee osteotomy surgery. Our findings also suggest that smokers have a better chance of achieving union with closing wedge osteotomy compared to open wedge osteotomy.

Osseointegration of implants with superhydrophilic surfaces in rats with high serum levels of nicotine

This study aimed to evaluate the effect of nicotine administration on the osseointegration of a superhydrophilic implants surface on rat tibiae. Thirty-two rats were used and divided into 2 groups according to the administration or not of nicotine: HH - Installation of implants with superhydrophilic surfaces in healthy animals; and HN - Installation of implants with superhydrophilic surfaces in animals subjected to nicotine administration. The animals were euthanized 15 and 45 days after implant placement (n = 8). Osseointegration was assessed by means of biomechanical analyses (removal torque), microcomputed tomography (volume of bone around the implants- %BV/TV), and histomorphometry (bone-implant contact -%BIC and the bone area between implant threads -%BBT). The animals subject to the nicotine administration presented lower removal torque than the control animals at the 45-day period (21.88 ± 2.80 Ncm vs. 17.88 ± 2.10 Ncm). The implants placed in the control rats presented higher %BIC (54.26 ± 6.59% vs. 39.25 ± 4.46%) and %BBT (50.57 ± 5.28% vs. 32.25 ± 5.24%) than the implants placed in nicotine animals at 15-day period. The nicotine administration reduces the osseointegration at 15 days, however, the superhydrophilic surface equalized the osseointegration in nicotine-exposed animals compared with healthy animals after 45 days of implant placement.

Opening-Wedge High Tibial Osteotomy With High Hinge Position Risks Lateral Hinge Fracture in Men With Posterolateral Tibial Condyle Protrusion

PURPOSE

The primary aim of this study was to evaluate the 3-dimensional morphology of the proximal tibia around the osteotomy plane in open-wedge high tibial osteotomy, focusing on the posterolateral (PL) and posteromedial (PM) tibial condyles, and to clarify the changes in morphologic parameters due to differences in patient characteristics and hinge position. The secondary aim was to examine whether morphologic features were associated with insufficient osteotomy, which increases the risk of lateral hinge fracture (LHF).

METHODS

The PL and PM anteroposterior distance, asymmetry ratio, and discrepancy between PL and PM distances along the tibial osteotomy plane were measured. We investigated changes in the parameters due to differences in patient characteristics and hinge position. Osteotomy configurations and LHFs were evaluated using postoperative computed tomography scans.

RESULTS

The 3-dimensional preoperative plans of 117 knees (male, 41 knees; female, 76 knees) were evaluated. PL distances were larger than PM distances in almost all cases. The average asymmetry ratio was 1.35, and the standard deviation was 0.22. Higher hinge position was associated with a larger asymmetry ratio and discrepancy (P < .001). The asymmetry ratio and discrepancy were independently positively correlated with male sex (P = .002 and P = .001, respectively) and gentle posterior tibial slope (P < .001 and P < .001, respectively). Osteotomies with type III LHFs showed lower osteotomy sufficiency than osteotomies without LHFs (P < .001).

CONCLUSIONS

PL tibial condyle protrusion was more pronounced in male patients and those with a high hinge position, and may result in insufficient PL osteotomy, which is a risk factor for type III LHF during open-wedge high tibial osteotomy. The optimal hinge position was located approximately 15 mm and 20 mm distal to the lateral tibial plateau in female and male patients, respectively.

LEVEL OF EVIDENCE

IV: retrospective case series.

Double level osteotomy for medial osteoarthritis and bifocal varus malalignment has excellent short-term results while maintaining physiologic radiographic joint parameters

PURPOSE

The purpose of this study was to prospectively evaluate the clinical and radiological results of double level osteotomy (distal femoral lateral closed wedge and proximal tibial medial open wedge) in medial osteoarthritis and varus malalignment due to bifocal deformity of femur and tibia.

METHODS

From 2017 to 2019 all cases of DLO in osteoarthritic varus malaligned knees with bifocal deformity (femoral and tibial deformity) were prospectively enrolled into this observational therapeutic study. Evaluation was performed preoperatively, at six, twelve, 18 and 24 months with regard to survival (not requiring arthroplasty), functional outcome [subjective International Knee Documentation Committee score (IKDC), Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome score (KOOS) and Tegner Activity Scale], pain level (numeric rating scale), subjective satisfaction (rating 1-5), radiographic parameters on a pre-and postoperative full leg x-rays (mechanical axis, mechanical proximal tibial and distal femoral angles) and complications. For statistical evaluation student's t test, Mann-Whitney U test and Wilcoxon-signed-rank test were used.

RESULTS

Fifty-two consecutive cases in 48 patients were enrolled in the study. Three cases were excluded, resulting in a follow-up rate of 94%. No arthroplasties were performed within follow-up. All functional outcome scores substantially and significantly increased as early as six months after the index procedure and further increased until final follow-up (p < 0.001). Pain level significantly decreased (p < 0.001). At final follow-up all patients stated that they would retrospectively undergo the operation again, and rated the result with 4.5 ± 0.6 out of 5 (3-5). Radiographic parameters were within physiological limits postoperatively. No severe complications occurred.

CONCLUSIONS

Double level osteotomy has excellent short-term results while maintaining physiological radiographic parameters. Therefore, it should be an integral part and standard procedure in realignment surgery for monocompartimental osteoarthritis.

LEVEL OF EVIDENCE

IV (prospective observational therapeutic study).

Opening- and closing-wedge high tibial osteotomy are comparable and early full weight bearing is safe with angular stable plate fixation: a meta-analysis

PURPOSE

The purpose of this study was to establish the gold standard for surgical technique, fixation, and rehabilitation for HTO in patients with unicompartmental knee osteoarthritis.

METHODS

Medline, Embase, and SPORTDiscus databases were searched up to April 2022. Included were (1) randomized controlled trials (RCTs) comparing opening-wedge HTO (owHTO) and closing-wedge HTO (cwHTO), (2) biomechanical studies and prospective patient studies comparing biomechanical and clinical results for plate fixators, and (3) RCTs comparing an early versus delayed full-weight-bearing (FWB) protocol.

RESULTS

The pooled results for the surgical technique showed no significant differences between owHTO and cwHTO for most PROMs on pain, activity, and risk for conversion to TKA. The cwHTO group showed a slightly better improvement in KOOS/WOMAC pain scores (4.51; 95% CI 1.18-7.85), and a significantly lower change in posterior tibial slope (p = 0.03). The pooled results for the fixation method showed the highest force at maximum failure for the Activmotion (Newclip Technics, France), Aescula (B. Braun Korea, Korea), 2nd generation Puddu (Arthrex Inc., USA), and TomoFix plate (Depuy Synthes, Switzerland). The pooled results for the rehabilitation protocol showed no significant differences between the early full-weight-bearing (FWB) group and the delayed FWB group for functional scores, complication rates, and delayed unions.

CONCLUSION

Both owHTO and cwHTO reduced pain and improved knee function. Locking plate fixation should be used for owHTO. An early FWB protocol has proven to be safe in patients with small corrections, no hinge fractures, and non-smokers.

LEVEL OF EVIDENCE

Level II.

Low-intensity pulsed ultrasound does not promote bone healing and functional recovery after open wedge high tibial osteotomy

Aims

To evaluate whether low-intensity pulsed ultrasound (LIPUS) accelerates bone healing at osteotomy sites and promotes functional recovery after open-wedge high tibial osteotomy (OWHTO).

Methods

Overall, 90 patients who underwent OWHTO without bone grafting were enrolled in this nonrandomized retrospective study, and 45 patients treated with LIPUS were compared with 45 patients without LIPUS treatment in terms of bone healing and functional recovery postoperatively. Clinical evaluations, including the pain visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score, were performed preoperatively as well as six weeks and three, six, and 12 months postoperatively. The progression rate of gap filling was evaluated using anteroposterior radiographs at six weeks and three, six, and 12 months postoperatively.

Results

The pain VAS and JOA scores significantly improved after OWHTO in both groups. Although the LIPUS group had better pain scores at six weeks and three months postoperatively, there were no significant differences in JOA score between the groups. The lateral hinge united at six weeks postoperatively in 34 (75.6%) knees in the control group and in 33 (73.3%) knees in the LIPUS group. The progression rates of gap filling in the LIPUS group were 8.0%, 15.0%, 27.2%, and 46.0% at six weeks and three, six, and 12 months postoperatively, respectively, whereas in the control group at the same time points they were 7.7%, 15.2%, 26.3%, and 44.0%, respectively. There were no significant differences in the progression rate of gap filling between the groups.

Conclusion

The present study demonstrated that LIPUS did not promote bone healing and functional recovery after OWHTO with a locking plate. The routine use of LIPUS after OWHTO was not recommended from the results of our study. Cite this article: Bone Jt Open 2022;3(11):885–893.

Assessment of the deformation model of the proximal tibia in the course of degenerative disease: analysis of the 3-dimensional mathematical model

Background

The high tibial osteotomy (HTO) is an effective knee-saving procedure, which relieves arthritis symptoms and prolongs the life of the knee joint. This procedure requires detailed preoperative planning. Usually, the contralateral side is used as a template for this purpose. Some intra-operative complications made us thinking how exactly the degenerative disease alter the epiphysis if the tibia. Our study aimed to assess morphological differences between healthy knees and degenerative knees using a three-dimensional mathematical model.

Methods

Twenty-three computed tomography (CT) examinations were collected out of 237 individuals screened for inclusion/exclusion. The inclusion criteria were: age between 40 and 69 years, degenerative knees with visible varus deformation, and signs of radiological osteoarthritis (OA) in the knee joint (such as joint space narrowing, subchondral sclerosis, subchondral cyst formation, and osteophytes. The average age of the included patients was 56.2 years. Nine men’s and 14 women’s knee joints were used for the calculation and comparisons.

Results

Female varus knees showed much more significant variability in tibial plateau dimensions according to sides of the body than male ones. These differences were statistically significant (P=0.03). In comparison between the basal bone and bones with OA, variability in 3D dimensions was statistically significant only for lateral condyles in males’ right knees (P=0.025). Compared to the degenerative knees to the most average, healthy knees, there were significant differences in the measured surface area of males’ right knees for both condyles: for the medial P=0.0046, for lateral P=0.005. Male varus knees had a statistically more considerable (P=0.028) surface area for all measured condyles. Angles of inclination differ significantly between knees with OA and healthy knees in the male population for the medial condyle plateau in the left knees. The female population for the lateral condyle in left knees and the medial condyle in right knees.

Conclusions

The proximal tibial plateau deformation showed high variability in the two-dimensional and three-dimensional analysis in the designed mathematical models. This finding must be considered during preoperative planning.

Bone healing on serial plain radiographs occurs slowly but adequately after medial opening wedge high tibial osteotomy without bone graft

PURPOSE

The purpose of this study was to prospectively investigate osteotomy gap filling rates on serial plain radiographs, and to evaluate whether alignment correction is maintained after medial opening wedge high tibial osteotomy (MOWHTO) using a locking plate without bone graft.

METHODS

Between March 2014 and June 2017, MOWHTO was performed without bone graft regardless of gap size. Radiographs were taken preoperatively, postoperatively, at 1, 3, 6, 12, 18, and 24 months after surgery. Radiographic examinations included a weight bearing long-standing anteroposterior (AP) view of the whole lower extremity, as well as, the AP, lateral, and both oblique views of the knee. Bone healing was measured on the medial oblique view of the knee. The postoperative alignment correction and its maintenance were assessed using the three radiologic parameters of the weight-bearing line (WBL) ratio, the hip-knee-ankle angle (HKAA), and the medial proximal tibial angle (MPTA) on the weight-bearing long-standing AP view of the lower extremity.

RESULTS

Fifty-two consecutive patients underwent MOWHTO, but three patients failed to follow-up for more than 24 months. A total of 49 patients were assessed in this study. The median opening gap height was 10.0 mm (IQR, 8.0-12.0; range, 7-20). On immediate post-operative radiographs, the mean gap filling was 31.4 ± 3.6%. After 1, 3, 6, 12, 18, and 24 months, the mean gap filling rates increased to 38.7 ± 4.4%, 51.4 ± 6.6%, 66.5 ± 5.1%, 84.8 ± 7.0%, 92.4 ± 5.6%, and 97.8 ± 2.3%, respectively. Statistical differences were observed between all the follow-up evaluations (P < 0.001). Statistical differences in the WBL ratio, HKAA, and MPTA were observed between preoperatively and 1 month after surgery (P < 0.001). The mean PTSA increased significantly from preoperatively to postoperatively (P < 0.001). However, no statistical differences were found between the post-operative follow-up radiographs performed for these four values.

CONCLUSION

MOWHTO using a locking plate without bone graft achieved at least 90% bone healing and had no loss in correction at 2 years postoperatively.

LEVEL OF EVIDENCE

III.

Assessment of morphological differences of the proximal tibia in healthy knees: analysis of the 3-dimensional mathematical model

Background

High tibial osteotomy and many orthopedic surgical procedures around the knee joint requires precise preoperative planning. In-depth knowledge of the tibial plateau morphology is necessary to limit intraoperative complications like lateral hinge fracture. No studies were exploring the differences in proximal tibia surface geometry, in regards to gender and laterality, using a mathematical model. The aim of our study was to assess morphological differences in healthy knees using a three-dimensional mathematical model.

Methods

Eighty-seven computed tomography examinations collected from 52 patients were selected for the study. The inclusion criteria were: age between 20 and 40 years, knee joint without visible deformities, no history of significant trauma to index knee, no history of systemic and chronic disorders. The average age of the included patients was 32.5±8.9 years old. For the calculation and comparisons, 45 right knee joints (18 females and 27 males) and 42 left knee joints (17 females and 25 males) were used.

Results

The male tibial plateau was much larger than the female one, for the right (P=0.001) and left knees (P=0.001). Male knees showed much bigger variability in two-dimensional tibial plateau dimensions especially for the left knees (P=0.001), and there was also a marked difference in variability between sides in males. Three-dimensional variability was significant for medial condyles for both genders. Male knees had a statistically bigger (P=0.04) tibial plateau surface area for all measured condyles.

Conclusions

The proximal tibial plateau showed in the designed mathematical models high variability in the two-dimensional and three-dimensional analysis. The males' knees presented great variability between sides and condyles. This finding must be considered during preoperative planning.

Hinge fracture in lateral closed-wedge distal femoral osteotomy in knees undergoing double-level osteotomy: assessment of postoperative change in rotational alignment using CT evaluation

PURPOSE

The purpose of this study was to examine the radiological features of hinge fracture occurring at the distal medial femoral cortex in knees undergoing biplanar lateral closed-wedge distal femoral osteotomy (LCW-DFO) in double-level osteotomy (DLO) based on pre- and postoperative CT image analyses. It was hypothesised that medial hinge fractures in LCW-DFO would occur with a similar incidence to that in high tibial osteotomy, and its occurrence would affect the clinical/radiological outcomes and induce unintended change in alignment depending on the fracture type (direction of the fracture).

METHODS

A consecutive series of 36 knees (31 patients) with primary varus osteoarthritis undergoing DLO comprised the study population. The mean age at surgery was 62.0 ± 5.9 years. Presence of hinge fracture was assessed on radiographs and CT images at 1 week. The fracture type was classified depending on the direction of the fracture line: crack propagation in line with the osteotomy (type 1) and fractures extending proximally (type 2) or distally (type 3) from the tip of the wedge. Computer-assisted assessments of bony limb alignment and bony geometry were conducted on a full-length weight-bearing radiograph and CT images using image analysis software. In addition, subjective clinical results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS). Radiological and clinical follow-up results at 1 and 2 years were compared to the preoperative data, while comparative analysis was made between the subjects with and without a hinge fracture.

RESULTS

Postoperative image examinations revealed type 1 and 2 medial femoral hinge fractures in 4 and 7 knees, while no type 3 fracture was identified in the study population. Consequently, the overall incidence of the hinge fracture was 30.6% (11 of the 36 knees). Four of those 11 fractures (36.4%) could not be detected on plain radiographs. CT image analysis for three-dimensional bony geometry showed greater increase in internal rotation of the distal bony segment (increased femoral antetorsion by 9.5° on average) after surgery compared to the knees without a hinge fracture (P = 0.01). Clinical evaluation using the KOOS at 2 years showed no significant difference between the groups with and without hinge fractures.

CONCLUSION

In LCW-DFO, medial femoral hinge fractures occurred in 30.6% of the cases. Knees with type 1 hinge fracture exhibited significantly greater increase in femoral antetorsion as compared to those without hinge fracture. In this case series, postoperative weight-bearing protocol was delayed for knees with hinge fracture. Consequently, surgical results were not affected by the occurrence of hinge fracture for up to 2 years.

LEVEL OF EVIDENCE

IV (case series).

Role of high tibial osteotomy in medial compartment osteoarthritis of the knee: Indications, surgical technique and outcomes

Knee osteoarthritis (OA) is the most common joint disorder worldwide. In particular, primary knee OA often presents with a varus malalignment. This increases the loads going through the medial compartment resulting in cartilage degeneration and symptomatic arthritis. High tibial osteotomy (HTO) is the workhorse surgical procedure for treating medial knee OA. When performed precisely in the hands of an experienced surgeon, HTO can delay or avoid knee arthroplasty. Of note, outcomes of knee arthroplasty are at best unpredictable in patients of younger age. Hence, there is a growing need for joint preservation procedures for younger patients presenting with knee OA, of which HTO is one. Through this article, the authors of whom all are joint preservation surgeons with a special interest in osteotomy hope to share from their experience as well as the available literature on the indications, perioperative planning, surgical technique, outcomes as well as pearls and pitfalls of HTO.

Risk Factor Analysis for Infection after Medial Open Wedge High Tibial Osteotomy

Background: Medial open wedge high tibial osteotomy (MOWHTO) is a well-established treatment for osteoarthritis of the medial tibiofemoral compartment. Surgical site infection (SSI) after MOWHTO is a devastating complication that may require further surgery. In this study, we aimed to identify the risk factors for infection after MOWHTO over 1 to 4 years of follow-up. Methods: Fifty-nine patients who underwent MOWHTO combined with knee arthroscopic surgery were included in this prospective study. Artificial bone grafts were used in all cases. Possible risk factors, including sex, age, body mass index (BMI), underlying disease, hospitalization length, correction angle, and surgery time, were recorded. Both univariate and multivariate analysis were used. Results: A total of 59 patients who underwent 61 operations were included. Eleven patients (18.0%) were reported to have SSI. Univariate analysis showed that smoking and diabetes mellitus were positively associated with SSI. Multivariate analysis showed that smoking and age were positively associated with SSI. Three patients (4.9%) were reported to suffer from deep SSI, requiring surgical debridement, all of whom were male smokers. Conclusion: Smoking, diabetes mellitus, and old age were identified to be possible risk factors of SSI after MOWHTO. These findings are common risk factors of SSI after orthopedic surgery according to the literature. Patient selection should be performed cautiously, and postoperative prognosis for MOWHTO should be carefully explained to patients who smoke.

Computed Tomography Detects Hinge Fractures After Medial Opening Wedge High Tibial Osteotomy: A Systematic Review

PURPOSE

To quantify the increased detection rate of lateral hinge fractures (LHFs) owing to additional computed tomography (CT), determine factors associated with LHFs, and compare radiologic and clinical outcomes of LHFs after medial opening wedge biplanar high tibial osteotomy (MOW-HTO).

METHODS

The MEDLINE, Embase, Cochrane Library, and Web of Science databases were systematically searched to identify studies reporting the incidence of LHFs detected using additional CT, showing radiologic factors, or comparing radiologic and clinical outcomes between LHFs and non-LHFs after MOW-HTO. Subgroup analyses were performed to compare stable and unstable LHFs. Two reviewers performed the study screening, risk-of-bias assessment, and data extraction processes.

RESULTS

Eleven studies were included in this review. The weighted estimate of the apparent incidence of LHFs in the pooled studies was 24.8%. The weighted estimate of the incidence was increased by 9.9% owing to the use of CT detection, which indicated that approximately 40% of total diagnosed LHFs were missed on plain radiographs or fluoroscopy. The pooled mean opening gap distance ranged from 11.40 to 12.60 mm in the LHF group and from 9.80 to 11.12 mm in the non-LHF group, and the mean difference in the opening gap distance was significantly larger in the LHF group (95% confidence interval, 0.64-1.84 mm; P < .0001). However, no significant differences in correction loss, bone union duration, and clinical outcomes were observed between the LHF and non-LHF groups. Subgroup analyses showed no significant differences between stable and unstable LHFs.

CONCLUSIONS

Postoperative CT evaluations increase the detection rate of LHFs compared with plain radiography alone. Furthermore, the opening gap distance was larger in the LHF group than in the non-LHF group, suggesting the need for attention when opening the wedge by more than 11.4 mm. However, the consequences of LHFs after MOW-HTO were not major concerns when proper management was provided.

LEVEL OF EVIDENCE

Level III, systematic review.

The degree of correction in open-wedge high tibial osteotomy compromises bone healing: A consecutive review of 101 cases

BACKGROUND

The bone healing in open-wedge high tibial osteotomy (OWHTO) proceeds gradually by a filling of the osteotomy gap. This can comprise several risk factors.

METHODS

A retrospective study analysed the clinical and radiological course of 101 consecutive OWHTOs in 96 patients. The following risk factors were considered: age, body mass index, tobacco consumption, amount of tobacco consumption, severity of comorbidities, infection of the surgical area, occurrence of a lateral hinge fracture and the degree of correction. The bone healing was evaluated by using the modified Radiographic Union Score for Tibial fractures (RUST).

RESULTS

A disturbance in bone healing was observed in 16 of the 101 osteotomies. Binary logistic regression analysis showed a correlation between the angle of the opening wedge and the development of a disturbance in bone healing (P = 0.002). The odds ratio indicated an increase in the risk of a disturbance in bone healing of 56% with each additional degree of correction. For the risk factor 'age' a statistical trend was recognizable (P = 0.077) with the risk of a disturbance in bone healing in higher age.

CONCLUSION

Lateral hinge fractures seem not to have a detrimental effect on the filling of the osteotomy gap. An increase in the opening wedge bears the risk of a disturbance in bone healing.

Combination of Cylindrical Autologous Bone Grafting Technique With a Metallic Block Insertion in Open-Wedge High Tibial Osteotomy

Open-wedge high tibial osteotomy (OW-HTO) is an effective surgical intervention for medial-compartment knee osteoarthritis. However, the osteotomized gap might be a disadvantage in OW-HTO because it can cause problems such as delayed bone union or loss of correction. These issues can be minimized by using autologous bone graft in the osteotomized gap, which is known to be the fastest and most clinically satisfactory gap filler. The primary mechanical stability of the osteotomy site in OW-HTO is essential for early weight bearing after surgery. Therefore, we introduce the combination of a cylindrical autologous bone grafting technique and a metallic block insertion for faster bone union and better primary stability of the site in OW-HTO. We expect that the described procedure will enable early postoperative weight bearing and, thereby, allow an early return to normal function.

Treatment of aseptic nonunion after medial opening-wedge high tibial osteotomy

BACKGROUND

Nonunion after medial opening-wedge high tibial osteotomy (OWHTO) is a rare but serious complication with very limited data regarding its treatment. The aim of this study was to analyze the healing rate after operative treatment of nonunion after OWHTO.

METHODS

We performed a single-center, retrospective study that included 14 patients with nonunion after OWHTO between 2010 and 2018. The treatment for all patients consisted of local debridement and cancellous bone grafting at the osteotomy gap. Revision osteosynthesis due to a loss of correction/loosening of the locking screws or plates was performed in 5 patients. In 7 patients, lateral hinge fractures were treated with additional lateral plating. Union was confirmed using the modified "Radiographic Union Score for Tibial fractures". Outcome measure was the Lysholm Knee Score at final follow-up.

RESULTS

The mean age of the patients included in our study was 48.4 ± 6.7 years. Three patients were female (21.4%). The mean follow-up period was 20.8 ± 12.8 months. Union was achieved in 12/14 patients (85.7%) after a mean of 6 months (range, 3-13). The mean Lysholm Knee Score at the final follow-up was 83.2 ± 11.6. Two patients did not reach definitive union during the follow-up. In one patient, an infection of the nonunion following bone grafting was successfully treated with a two-stage procedure. Two patients needed additional cancellous bone grafting 6 and 8 months after the first revision surgery. All patients showed pain-free full weight bearing after union was achieved.

CONCLUSIONS

Nonunions after OWHTO can generally be treated successfully with cancellous bone grafting. For patients who have loss of correction, loosening of the osteosynthetic material or fracture of the lateral hinge, an additional revision or additive osteosynthesis may be required.

LEVEL OF EVIDENCE

Grade III.

Recombinant Human BMP6 Applied Within Autologous Blood Coagulum Accelerates Bone Healing: Randomized Controlled Trial in High Tibial Osteotomy Patients

Bone morphogenetic proteins (BMPs) are potent osteogenic proteins that induce new bone formation in vivo. However, their effect on bone healing in the trabecular bone surfaces remains challenging. We evaluated the safety and efficacy of recombinant human BMP6 (rhBMP6) applied within an autologous blood coagulum (ABC) in a surgically created wedge defect of the proximal tibia in patients undergoing high tibial osteotomy (HTO) for varus deformity and medial osteoarthritis of the knee. We enrolled 20 HTO patients in a randomized, placebo-controlled, double-blinded phase I/II clinical trial. RhBMP6/ABC (1.0 mg/10 mL ABC prepared from peripheral blood) or placebo (10 mL ABC containing excipients) was administered into the tibial wedge defects. Patients were followed for 0 to 24 months by clinical examination (safety) and computed tomography (CT) and serial radiographic analyses (efficacy). The results show that there were no detectable anti-rhBMP6 antibodies in the blood of any of the 20 patients at 14 weeks after implantation. During the 24 months of follow-up, there were no serious adverse reactions recorded. The CT scans from defects of patients treated with rhBMP6/ABC showed an accelerated bone healing compared with placebo at 9 weeks (47.8 ± 24.1 versus 22.2 ± 12.3 mg/cm³ ; p = 0.008) and at 14 weeks (89.7 ± 29.1 versus 53.6 ± 21.9 mg/cm³ ; p = 0.006) follow-up. Radiographic analyses at weeks 6 and 24 and months 12 and 24 suggested the advanced bone formation and remodeling in rhBMP6/ABC-treated patients. In conclusion, we show that rhBMP6/ABC at a dose of 100 μg/mL accelerated bone healing in patients undergoing HTO without serious adverse events and with a good tolerability compared with placebo alone. Overall, for the first time, a BMP-based osteogenic implant was examined against a placebo for bone healing efficacy in the trabecular bone surface, using an objective bone mineral density measurement system. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

[Early effectiveness analysis of lateral hinge fracture during medial opening-wedge high tibial osteotomy]

OBJECTIVE

To compare the clinical and radiologic effectiveness in patients with versus without lateral hinge fracture during medial opening-wedge high tibial osteotomy (MOWHTO) to evaluate the effect of lateral hinge fracture on short-term effectiveness.

METHODS

The clinical data of 84 patients (97 knees) with medial compartment osteoarthritis who treated with MOWHTO between September 2015 and July 2018 was retrospectively analyzed. There were 10 males (10 knees) and 74 females (87 knees). The age ranged from 45 to 65 years with an average of 57.7 years. Lateral hinge fracture was recognized by the intraoperative fluoroscopy or immediate postoperative X-ray film. Fractures were classified into types Ⅰ, Ⅱ, and Ⅲ according to the Takeuchi classification. The healing of osteotomy was observed by radiographs during follow-up; the femur tibia angle (FTA), medialproximal tibial angle (MPTA), and hip-knee-ankle angle (HKA) were also calculated. The knee joint function was evaluated by Hospital for Special Surgery (HSS) score and knee society score (KSS).

RESULTS

The incision healed by first intention. All patients were followed up 15-48 months with an average of 24.8 months. No hinge fracture occurred in 78 knees (80.41%, group A), and lateral hinge fractures were observed in 19 knees (19.59%, group B) and were divided into the type Ⅰ (13 knees, 13.40%) and type Ⅲ (6 knees, 6.19%) groups. Type Ⅰ fractures were not additionally treated, type Ⅲ fractures were anatomic reduced fixed with additional lag screws. X-ray film and CT examination showed that all patients had bone healing at 3 months after operation without delayed healing or nonunion. During follow-up, there was no loosening or fracture of internal fixation plates and screws. HKA, FTA, and MPTA of patients in group A and group B (type Ⅰ and Ⅲ) were significantly improved at each time point after operation compared with preoperative values ( P<0.05); there was no significant difference between groups at each time point before and after operation ( P>0.05). After operation, the pain of knee joint was alleviated and the function of joint was improved. At last follow-up, KSS score and HSS score of groups A and B were significantly improved compared with those before operation ( P<0.05), but there was no significant difference between the two groups ( P>0.05).

CONCLUSION

The lateral hinge fracture may occur during MOWHTO. As long as the treatment and rehabilitation were guided according to the fracture classification of the hinge, the effectiveness can be similar to those without the hinge fracture.

OPTY-LINE remote-controlled adjustable intramedullary device implantation in open-wedge high tibial osteotomy: A prospective proof-of-concept pilot and comparison with Tomofix fixed-plate device method

PURPOSE

The objective was to evaluate the clinical and patient-related short- to medium-term performance of the OPTY-LINE nail device for high tibial osteotomy (HTO), comparing a case series of the said device to the established Tomofix fixed-plate device.

PATIENTS AND METHODS

Males with symptomatic medial compartmental osteoarthritis and no serious (co-morbid) knee pathology were followed up, five Tomofix and six OPTY-LINE patients. Patients underwent computed tomography assessment and completed Knee Injury and Osteoarthritis Outcome score (KOOS) and osteotomy surgery patient satisfaction questionnaires, 3 and 6 months post-surgery. A radiologist impression score and a quantitative digital bone density analysis were performed by two independent radiologists. Mann-Whitney U test was applied for inferential statistical tests.

RESULTS

At 6 months post-surgery, for Tomofix, the median radiologists' healing impression score was 'progressive healing' versus 'union virtually complete' for the OPTY-LINE nail; bone healing quotient was 1.30 (standard deviation (SD) 1.74) versus 1.78 (SD 1.58), p = 0.18. The post-operative absolute surgical accuracy was a mean 12 (7.5) for Tomofix versus 4.1 (2.3) for OPTY-LINE, p = 0.052. At baseline, however, Tomofix patients had more knee symptoms, as determined by KOOS symptom sub-score, when compared to the OPTY-LINE cohort (p = 0.009).

CONCLUSION

This initial, non-randomized, comparative evaluation of the OPTY-LINE device for HTO has produced similar outcomes to patients treated with the established Tomofix device. In particular, the rate of post-surgical bone regeneration and surgical accuracy achieved with the OPTY-LINE device are encouraging. Large-scale randomized controlled studies with longer follow-up are indicated to further evaluate the clinical and patient-related outcome performance for OPTY-LINE.

The factors affecting the timing of bone union after closing-wedge high tibial osteotomy

OBJECTIVE

Closing-wedge high tibial osteotomy (CWHTO) for medial osteoarthritis of the knee is one of the effective osteotomy methods, especially for patients with cartilage damage of the patellofemoral joint, flexion contracture, and requiring a large correction angle.While the bone union at the osteotomy site is finally obtained after CWHTO, there are often differences in the period of the bone union. The purpose of the present study is to investigate the factors affecting the timing of bone union after CWHTO.

METHODS

16 cases of CWHTO were included; they were performed by the same surgeon using precisely the same implants. Among 16 cases in the present study, nobody used low-intensity pulsed ultrasound (LIPUS) within three months after the operation. The patients were divided into two Groups using Plane X-ray and CT within three months after surgery: Group D (8 knees; bone healing was not seen at all) and Group E (8 knees; bone healing was seen).

RESULTS

There were no significant differences in mean age between the two groups, but body mass index (BMI) and bone mineral density (BMD) were significantly higher in Group D (p < 0.05).

CONCLUSION

The present study suggests that BMI and BMD may affect the timing of bone union after CWHTO.

BACKGROUND

Closing-wedge high tibial osteotomy (CWHTO) for medial osteoarthritis of the knee is one of the effective osteotomy methods. The frequency of selecting CWHTO in our hospital in Japan is high, especially for patients with cartilage damage of the patellofemoral joint, flexion contracture, and requiring a large correction angle. On the other hand, while the bone union at the osteotomy site is obtained with both procedures, there are often differences in bone union time for CWHTO compared to Opening-wedge high tibial osteotomy (OWHTO). This difference might affect the early clinical outcome of the operations. We hypothesized that there is some factor to affect bone healing of CWHTO for individual patients.

PURPOSE

To investigate the factors affecting the timing of bone union after CWHTO.

Biomechanical effect of a lateral hinge fracture for a medial opening wedge high tibial osteotomy: finite element study

BACKGROUND

This study aimed to investigate the biomechanical effect on the Takeuchi classification of lateral hinge fracture (LHF) after an opening wedge high tibial osteotomy (HTO).

METHODS

We performed an FE simulation for type I, type II, and type III in accordance with the Takeuchi classification. The stresses on the bone and plate, wedge micromotion, and forces on ligaments were evaluated to investigate stress-shielding effect, plate stability, and biomechanical change, respectively, in three different types of LHF HTO and with the HTO without LHF model (non-LHF) models.

RESULTS

The greatest stress-shielding effect and wedge micromotion were observed in type II LHF (distal portion fracture). The type II and type III (lateral plateau fracture) models exhibited a reduction in ACL force and an increase in PCL force compared with the HTO without LHF model. However, the type I (osteotomy line fracture) and HTO without LHF models did not exhibit a significant biomechanical effect. This study demonstrates that Takeuchi type II and type III LHF models provide unstable structures compared with the type I and HTO without LHF models.

CONCLUSIONS

HTO should be performed while considering a medial opening wedge HTO to avoid a type II and type III LHF as a potential complication.

Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy with a beta-tricalcium phosphate block

BACKGROUND

The purpose of this study was to investigate the healing process of synthetic bone grafts in opening wedge high tibial osteotomy (OWHTO) and to identify the factors that affect bone healing in OWHTO. It was hypothesized that lateral hinge fracture (LHF) is associated with delayed bone healing after OWHTO with synthetic bone grafting.

METHODS

The subjects included 350 knees of 283 patients who underwent OWHTO using two wedged blocks of beta-tricalcium phosphate (β-TCP) with 60% porosity. The healing of the osteotomy gap using a radiologic rating system for OWHTO with synthetic bone grafts and the presence of an LHF were assessed up to postoperative 24 months.

RESULTS

LHFs were found in 49 knees (14%). The osteotomy gap showed slower progression of radiographic healing with an LHF than without an LHF (P < .05). In the knees with LHFs, initial radiographic change in the osteotomy gap was observed almost at the same time as healing of the LHF. Multivariate logistic regression analysis identified LHF as the factor preventing the progression of bone healing (OR = 46.78, P < .05).

CONCLUSIONS

LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting.

Plate-related results of opening wedge high tibial osteotomy with a carbon fiber reinforced poly-ether-ether-ketone (CF-PEEK) plate fixation: a retrospective case series of 346 knees

BACKGROUND

While open wedge high tibial osteotomy (owHTO) is an established standard procedure to treat medial osteoarthritis of the knee in combination with varus deformity, it bears the risk of postoperative hardware failures and lateral cortical hinge fractures. This in turn can lead to an accelerated osteoarthritis, non-union, or a loss of correction accuracy. The purpose of the study was to evaluate the radiologic outcomes of owHTO with a carbon fiber reinforced poly-ether-ether-ketone (CF-PEEK) plate fixation in patients with medial osteoarthritis and varus deformity.

METHODS

Three hundred twenty-four consecutive patients (346 knees) who were treated with owHTO using the PEEKPower HTO plate were included in this retrospective study; 89.9% of the patients were overweight or obese. Patients were followed by conventional radiographs over a 12-month period. Typical plate-related results such as the time and quality of gap healing as well as the correction accuracy were analyzed. Furthermore, the number of lateral cortex fractures was determined.

RESULTS

Bony consolidation was observed after a mean gap healing time of 4.0 ± 1.7 months independent on the patients' weight (p = 0.2302). With increasing gap sizes, bony healing was significantly prolonged (p < 0.001). Additionally, patients with greater gap sizes had a significantly increased risk for a lateral cortex fracture (p = 0.0041). However, none of the patients had a non-union 1 year postoperative. A hinge fracture occurred in 30% of patients. Hinge fractures with Takeuchi grades I and II increased the gap healing time compared to no fracture (p = 0.0069 and p = 0.0002, respectively), but only 1.2% of patients with hinge fracture had a clinical relevant loss of correction ≥ 3 mm. No implant failures were found.

CONCLUSIONS

Open wedge HTO using the PEEKPower HTO plate for patients with medial osteoarthritis of the knee in combination with tibial varus deformity leads to excellent bony consolidation also in cases with a hinge fracture, a gap size > 12 mm as well as for severely obese patients.

Tibial rotational alignment after opening-wedge and closing-wedge high tibial osteotomy

A lot of good outcomes have been reported after opening-wedge high tibial osteotomy (OWHTO) and closing-wedge high tibial osteotomy (CWHTO).The purpose of this study was to examine the rotational alignment after OWHTO and CWHTO performed by the same surgeon in one hospital.

The sample included 30 knees from 24 patients. In all cases, the same orthopaedic surgeon performed the osteotomy surgeries using the same method. The tibial external rotation angle (TERA) was measured using the CT images of proximal tibial plateau and distal tibial malleolus from the consecutive axial CT slices of tibia. In this study, two considerations were examined. The first was the change in rotation angle, which was defined by TERA noted before and after the operation. The second was the relationship between the correction angle of the osteotomy and the rotation angle change of the distal tibia. The first was evaluated using the paired-Student’s t-test, while the second was analyzed with Pearson’s correlation coefficient. In the OWHTO group, the mean TERA was 21.4± 7.0° preoperatively and 20.2 ± 8.0° postoperatively, but no significant difference was seen between pre- and post-operation measurements (p = 0.21). Significant TERA increasing (that is, external rotation of the distal tibia) was seen postoperatively in only three knees. In the CWHTO group, the mean TERA was 19.9 ± 10.5° preoperatively and 16.5 ± 9.5° postoperatively, and significant difference was seen between pre- and post-operative TERA (p < 0.05). No significant correlation was seen between the correction angle and the change of the rotation angle in either group (r = 0.40, r = 0.12) .

In the OWHTO group, both internal and external rotation of the distal tibia can occur after surgery. In the CWHTO group, the distal tibia rotated internally postoperatively. No significant correlation was seen between the correction angle and the change in the rotation angle in either group

Factors affecting stability after medial opening wedge high tibial osteotomy using locking plate: A cadaveric study

OBJECTIVES

To investigate the effect of screw length, lateral hinge fracture, and gap filling on stability after medial opening wedge high tibial osteotomy (MOW HTO) using a locking plate.

METHODS

Forty tibiae from fresh-frozen cadavers were randomly allocated into five groups. Group A was bicortically fixated, while Group B and Group C were unicortically fixated: 90% and 55% of drilled tunnel length, respectively. Group D was fixated using 90% length screws with a fractured lateral hinge. Group E was fixated using 90% length screws with gap filling using a bone substitute. Operated tibiae were tested under axial compressive load using a material testing machine. The medial gap changes under the serial axial load of 100-600 N and ultimate failure load were measured.

RESULTS

Group D showed the biggest medial gap change and lowest failure load, while Group E presented the smallest gap change and highest failure load. The medial gap changes tended to increase with shorter screw length, but the difference was not significant between Groups A, B, and C. Group C and Group D showed greater medial gap change and lower failure load compared with Group E, while not differing from Group A and Group B.

CONCLUSIONS

Unicortical fixation in proximal screw holes of a locking plate was not inferior to bicortical fixation regarding axial stability in MOW HTO, although proximal screws that are too short should be avoided. Lateral hinge fracture decreased, while gap filling with bone substitute increased axial stability.

Stress fractures of the lateral tibial plateau after open wedge high tibial osteotomy could be delayed type III lateral hinge fractures

Purpose

To examine the condition and triggers of stress fractures of the lateral tibial plateau (LTP) similar to type III lateral hinge fractures (LHFs) after open wedge high tibial osteotomy (OWHTO).

Methods

OWHTO was performed in 118 knees. They were examined for LHFs by computed tomography (CT). Patients were divided into the stress fracture group (Group SF) if they showed fracture lines on CT performed after starting weight-bearing walking and the normal group (Group N) for others.

Results

The mean age was significantly older in Group SF (P = 0.022). Preoperatively, Group SF showed a significantly higher tibio-femoral angle (TFA, P = 0.014). No significant differences were observed in TFA and weight-bearing line ratio after surgery. Correction angle was significantly higher in the SF group. And all of the SF were more than 13 degrees. There was no significant difference in LHF incidence between groups, whereas stress fracture incidence differed significantly for each type of LHF (chi-squared test, P = 0.0001): 14.6% of type I cases, 100% of type II cases, 0% of type III cases, and 6.1% of those without LHF.

Discussion

The load on the LTP is assumed to act as a shearing force in type II fractures, which may contribute greatly to stress fractures. In type III, stress fractures may not occur because of the load dispersed at the fracture part. The stress fracture site is similar to type III LHF, and this kind of fracture is thought to be a delayed type III because it occurs after patients start weight-bearing walking. Moreover, they are observed in type I cases with a stable hinge and in 6% of cases without LHF. This study showed that high varus knees corrected with a large correction angle may develop stress fractures. OWHTO requires attention to stress fractures of the LTP, which can be regarded as delayed type III, in those developing LHFs postoperatively or having a high varus knee preoperatively.

Conclusion

These results indicated the possibility of stress fracture in LTP during weight-bearing exercise after OWHTO, which was regarded as a delayed type III fracture. The results showed that Correction angle was more than 13 degrees, and lateral hinge fracture type II of the Takeuchi classification was an inducement of this stress fracture.

Level of evidence

Level IV.

Pulsed Electromagnetic Field Therapy Improves Osseous Consolidation after High Tibial Osteotomy in Elderly Patients-A Randomized, Placebo-Controlled, Double-Blind Trial

Extremely low-frequency pulsed electromagnetic field (ELF-PEMF) therapy is proposed to support bone healing after injuries and surgical procedures, being of special interest for elderly patients. This study aimed at investigating the effect of a specific ELF-PEMF, recently identified to support osteoblast function in vitro, on bone healing after high tibial osteotomy (HTO). Patients who underwent HTO were randomized to ELF-PEMF or placebo treatment, both applied by optically identical external devices 7 min per day for 30 days following surgery. Osseous consolidation was evaluated by post-surgical X-rays (7 and 14 weeks). Serum markers were quantified by ELISA. Data were compared by a two-sided t-test (α = 0.05). Device readouts showed excellent therapy compliance. Baseline parameters, including age, sex, body mass index, wedge height and blood cell count, were comparable between both groups. X-rays revealed faster osseous consolidation for ELF-PEMF compared to placebo treatment, which was significant in patients ≥50 years (∆_mean = 0.68%/week; p = 0.003). Findings are supported by post-surgically increased bone-specific alkaline phosphatase serum levels following ELF-PEMF, compared to placebo (∆_mean = 2.2 µg/L; p = 0.029) treatment. Adverse device effects were not reported. ELF-PEMF treatment showed a tendency to accelerate osseous consolidation after HTO. This effect was stronger and more significant for patients ≥50 years. This ELF-PEMF treatment might represent a promising adjunct to conventional therapy supporting osseous consolidation in elderly patients. Level of Evidence: I.

Mechanical strength of a new plate compared to six previously tested opening wedge high tibial osteotomy implants

Background

This study aimed to assess the mechanical static and fatigue strength provided by the FlexitSystem plate in medial opening wedge high tibial osteotomies (MOWHTO), and to compare it to six previously tested implants: the TomoFix small stature, the TomoFix standard, the ContourLock, the iBalance, the second generation PEEKPower and the size 2 Activmotion. Thus, this will provide surgeons with data that will help in the choice of the most appropriate implant for MOWHTO.

Methods

Six fourth-generation tibial bone composites underwent a MOWHTO and each was fixed using six FlexitSystem plates, according to standard techniques. The same testing procedure that has already been previously defined, used and published, was used to investigate the static and dynamic strength of the prepared bone-implant constructs. The test consisted of static loading and cyclical loading for fatigue testing.

Results

During static testing, the group constituted by the FlexitSystem showed a fracture load higher than the physiological loading of slow walking (3.7 kN > 2.4 kN). Although this fracture load was relatively small compared to the average values for the other Implants from our previous studies, except for the TomoFix small stature and the Contour Lock. During fatigue testing, FlexitSystem group showed the smallest stiffness and higher lifespan than the TomoFix and the PEEKPower groups.

Conclusions

The FlexitSystem plate showed sufficient strength for static loading, and average fatigue strength compared to the previously tested implants. Full body dynamic loading of the tibia after MOWHTO with the investigated implants should be avoided for at least 3 weeks. Implants with a wider T-shaped proximal end, positioned onto the antero-medial side of the tibia head, or inserted in the osteotomy opening in a closed-wedge construction, provided higher mechanical strength than implants with small a T-shaped proximal end, centred onto the medial side of the tibia head.

Analysis and quantification of bone healing after open wedge high tibial osteotomy

Background

The aim of this study was to analyze radiographic imaging techniques and to quantify bone ossification in the osteotomy gap after high tibial osteotomy.

Material and methods

Study phase 1: high tibial osteotomy was performed on six lower extremities of human body donors and experimental X‑rays and computed tomography (CT) scans were applied. Different techniques were evaluated by three specialists for best representation of the osteotomy gap.

Study phase 2: optimized radiological techniques were used for follow-up on 12 patients. The radiographs were examined by 3 specialists measuring 10 different parameters. The CT scans were analyzed with semiautomatic computer software for quantification of bone ossification.

Results

The osteotomy gap was best represented in 30° of flexion in the knee and 20° internal rotation of the leg. There were significant changes of the medial width over time (p < 0.019) as well as of the length of fused osteotomy, the Schröter score, sclerosis, trabecular structure and zone area measurements. Sclerosis, medial width of the osteotomy and area measurements were detected as reproducible parameters. Bone mineral density was calculated using CT scans, showing a significantly higher value 12 weeks postoperatively (112.5 mg/cm³) than at baseline (54.6 mg/cm³). The ossification of the gap was visualized by color coding.

Conclusion

Sclerosis and medial width of the osteotomy gap as well as area measurements were determined as reproducible parameters for evaluation of bone healing. Quantification of bone ossification can be calculated with CT scans using a semiautomatic computer program and should be used for research in bone healing.

Incidence and Predictors of Lateral Hinge Fractures Following Medial Opening-Wedge High Tibial Osteotomy Using Locking Plate System: Better Performance of Computed Tomography Scans

BACKGROUND

This study compared the rates of plain radiographs and computed tomography (CT) for detecting lateral hinge fractures and to evaluate factors affecting lateral hinge fractures in patients following medial opening-wedge high tibial osteotomy (MOWHTO).

METHODS

This prospective study included 59 patients (65 knees) undergoing MOWHTO for primary medial compartment osteoarthritis with a 2-year follow-up between 2013 and 2016. Clinical and radiographic evaluations were performed using Knee Society Score and Western Ontario and McMaster Universities Arthritis Index, and we calculated the hip-knee-ankle angle, weight-bearing line ratio, lateral distal femoral angle, medial proximal tibial angle, posterior tibial slope, osteotomy gap height, and osteotomy gap filling rate. Immediate plain radiographs and CT were used to detect lateral hinge fractures according to Takeuchi's method.

RESULTS

Among 65 knees, the incidence of lateral hinge fractures was 13.8% (Type I: 7, Type II: 2). Only 6 knee fractures (9.2%) were detected on postoperative plain radiographs, including 5 Type I fractures and 1 Type II fracture. An additional 3 knees (4.6%) were detected on postoperative CT scans, including 2 Type I fractures and 1 Type II fracture. Furthermore, osteotomy gap height (adjusted odds ratio = 1.831, P = .016) was the only predictor of lateral hinge fractures.

CONCLUSION

The incidence of lateral hinge fractures after MOWHTO was 13.8%. CT (13.8%) afforded higher detection rates for lateral hinge fractures than did plain radiographs (9.2%) despite a marginal difference with uncertain significance. Osteotomy gap height was the only predictor of lateral hinge fractures.

LEVEL OF EVIDENCE

Prospective cohort study (Level II).

Large opening gaps, unstable hinge fractures, and osteotomy line below the safe zone cause delayed bone healing after open-wedge high tibial osteotomy

PURPOSE

To evaluate bone formation in the osteotomy gap after open-wedge high tibial osteotomy (OWHTO), including after plate removal, and to investigate risk factors for delayed bone healing.

METHODS

Ninety-three patients (102 knees) who underwent OWHTO without bone grafting were enrolled. The osteotomy gap was divided into the lateral hinge and the four zones on anteroposterior radiographs, and we defined the zone in which trabecular bone continuity could be observed as gap filling. Bone formation in the osteotomy gap was evaluated according to this definition at 3, 6, and 12 months postoperatively; at plate removal; and at the final follow-up (mean, 62.3 ± 30.2 months). We also investigated the risk factors for delayed bone healing.

RESULTS

The lateral hinge united at 3 months postoperatively in 92 knees (90.2%). At 1 year postoperatively, 98 knees (96.1%) reached zone 1 and 92 knees (90.2%) reached zone 2. At plate removal, gap filling reached zone 2 in all cases and progressed further without loss of correction after plate removal. Opening width over 13.0 mm [odds ratio (OR): 1.61, P = 0.02], Takeuchi's classification type II lateral hinge fracture (OR: 20.4, P < 0.01), and osteotomy line below the safe zone (OR: 8.98, P < 0.01) significantly delayed bone formation after OWHTO.

CONCLUSIONS

Gap filling progressed from lateral to medial after OWHTO without bone grafting and progressed further after plate removal. Large opening gaps, unstable hinge fractures, and osteotomy line below the safe zone cause delayed bone healing after OWHTO.

Posterior cortical breakage leads to posterior tibial slope change in lateral hinge fracture following opening wedge high tibial osteotomy

PURPOSE

This study was designed to analyze the relationship between changes in posterior tibial slope and the absence or presence of lateral hinge fracture, diagnosed in the sagittal and axial planes, as well as the coronal plane, by computed tomography (CT) following opening wedge high tibial osteotomy (HTO).

METHODS

This study involved 55 patients (55 knees) undergoing opening wedge HTO for primary medial osteoarthritis. Lateral hinge fractures were evaluated on CT scans according to the Takeuchi classification and were also classified as subtypes A, B, and C, depending on anterior, posterior, and both anterior and posterior cortical disruptions, respectively, as determined by the sagittal and axial planes of CT scans which corresponded to the fracture line visible on coronal CT scans.

RESULTS

Of the 55 knees, 23 were found on postoperative CT scans to have lateral hinge fractures. All 23 were classified as Type I, with 11, 12, and 0 being subtypes A, B, and C, respectively. Mean change in posterior tibial slope from 3 weeks postoperatively to last follow up in subtype B was significantly greater than in subtype A (2.5° vs 0.2°, P = 0.008) and in knees without hinge fracture (2.5° vs 0.1°, P = 0.002).

CONCLUSION

Type I lateral hinge fractures encroached either the anterior or posterior cortex of the proximal tibia, but not both. In addition, posterior tibial slope increased over time following surgery in knees with Type I lateral hinge fracture and posterior cortex breakage, suggesting that caution should be exercised when deciding the starting time for weight bearing in such patients.

LEVEL OF EVIDENCE

Case series, Level IV.

[Study on lateral hinge fracture during open wedge high tibial osteotomy]

Objective

To summarize the related research results of open wedge high tibial osteotomy (OWHTO) complicated with lateral hinge fracture.

Methods

To review the relevant literature of OWHTO at home and abroad in recent years and summarize and analyse the clinical experience.

Results

The lateral hinge rupture may occur during the OWHTO, which may lead to the loss of correction angle after operation, delayed healing or non-union of osteotomy and so on. The lateral hinge plays an important role in the stability of the osteotomy. During the operation, the "safe zone" internal osteotomy can be used to protect the bone. Once the lateral hinge breaks, the TomoFix plate can be used to obtain the sufficient stability. For patients with lateral hinge rupture, functional exercise and full weight loading time should be guided by hinge breakage classification.

Conclusion

The intact lateral hinge is beneficial to the healing and rehabilitation of OWHTO. The lateral hinge should be paid enough attention by clinicians.

Biomechanical properties following open wedge high tibial osteotomy: Plate fixator combined with dynamic locking screws versus standard locking screws

BACKGROUND

Open wedge high tibial osteotomy is widespread in treating osteoarthritis of the knee. Bone healing of the gap and the necessity of bone substitutes are under discussion. Increasing movement of the osteotomy gap can improve bone healing, while excessive movement should be avoided. It was hypothesised that the use of dynamic locking screws, compared to standard locking screws, will increase interfragmental motion while construct stability persists.

METHODS

In 20 tibia sawbones open wedge high tibial osteotomy was performed using standard locking screws or dynamic locking screws. An incremental cyclic (2 Hz) compression to termination protocol was applied using a material testing machine (MTS MiniBionix 858). Relative motion of the osteotomy and construct stability were measured using an optical tracking system (PONTOS 5M system). Levels of significance were set to 0.05.

FINDINGS

19 Sawbones were statistically evaluated. Interfragmental motion increased significantly with dynamic locking screws compared to standard locking screws (P < 0.001). Lateral hinge fractured after a mean of 29,489 (dynamic locking screws) vs. 48,111 (standard locking screws) load cycles at a median load level 3 (50-1120 N) in dynamic locking screws group and at a median load level 5 (50-1440 N) (P = 0.002) in standard locking screws group.

INTERPRETATION

Using dynamic locking screws in open wedge high tibial osteotomy increases interfragmental motion within the range of optimal bone healing. A decrease in construct stability has to be considered compared to standard locking screws.

Extra-articular Lateral Hinge Fracture Does Not Affect the Outcomes in Medial Open-Wedge High Tibial Osteotomy Using a Locked Plate System

PURPOSE

To compare the radiologic and clinical outcomes in patients with and without lateral hinge fractures (LHFs) during medial open-wedge high tibial osteotomy (MOWHTO) using a locked plate system, as well as to assess whether LHFs could affect the midterm outcomes.

METHODS

From May 2008 to November 2015, 164 knees underwent MOWHTO using a locked plate system for the treatment of knee osteoarthritis. LHFs were recognized by radiographs during or after the high tibial osteotomy and were not additionally treated. In all patients, we applied the same rehabilitation protocol that allowed full weight bearing at 6 weeks. Patients were divided into LHF (types I and II) and nonfracture groups. Radiologically, we compared any serial changes in the hip-knee-ankle angle, femorotibial angle, medial proximal tibial angle, and posterior tibial slope angle from the immediate postoperative radiographs to the final radiographs. The union process of the osteotomy site among the groups was also evaluated. Clinically, the postoperative American Knee Society Score and knee range of motion at latest follow-up were compared. Postoperative complications were also evaluated.

RESULTS

The average age at operation was 56.0 years (range, 42-67 years), and the average follow-up period was 62.2 months (range, 24-120 months). LHFs were observed in 37 knees (22.6%) and were divided into the type I (16 knees) and type II (21 knees) groups. All groups showed no significant changes in serial evaluations of the postoperative hip-knee-ankle angle, femorotibial angle, medial proximal tibial angle, and posterior tibial slope angle. The improvements in the American Knee Society Score and knee range of motion were not significantly different among the groups. No patients showed correction loss or union problems.

CONCLUSIONS

Type I and II LHFs in MOWHTO using a medial locked plate system and relatively conservative rehabilitation protocol with full weight-bearing walking commenced at 6 weeks postoperatively showed no radiologic changes or functional deterioration during midterm follow-up.

LEVEL OF EVIDENCE

Level IV, case series.

Editorial Commentary: Lateral Hinge Fracture After Opening Wedge High Tibial Osteotomy With Long Locking Plate Use

Lateral hinge fracture (LHF) is a common complication after opening wedge high tibial osteotomy. Such a fracture can be caused by many factors such as osteotomy level, amount of opening, hinge position, and kind of plate. In particular, long locking plates have superior biomechanical stability in cases of LHF compared with short plates. Therefore, these long locking plates should be used in cases of LHF after opening wedge high tibial osteotomy.

Distal femoral varus osteotomy: results of the lateral open-wedge technique without bone grafting

Background

The lateral opening wedge distal femoral osteotomy (LOWDFO) to reconstruct knee alignment in patients with genu valgum originating in the distal femur has gained importance within the last years.

Purpose

To analyze clinical and radiographic outcome of patients treated with LOWDFO with respect to bone healing without grafting and patient age.

Material and methods

Twenty-two consecutive patients with genu valgum corrected with 23 LOWDFOs using a Tomofix-locking plate were retrospectively analyzed (mean age 23.7 years). Clinical evaluation was based on pre- and post-operative KOOS scores. A pre- and post-operative radiographic assessment, including MAD, mLDFA, LLD, bone healing, and patella parameters, was performed. Differences between subgroups (age, bone grafting) were analyzed.

Results

The restoration of MAD and mLDFA resulted in significantly improved post-operative KOOS₅ scores in younger and older patients (p = 0.001). Bone healing without bone grafting was reliable in all patients. The leg length was significantly increased post-operatively (p = 0.001). The Blackburne-Peel ratio was significantly reduced to more normal values post-operatively (p < 0.001).

Conclusion

LOWDFO without bone grafting is a reliable procedure representing a promising treatment option particularly in young patients with genu valgum. Besides correction of the MAD, a significant leg length increase and additional patella stability can be expected.