Open Wedge High Tibial Osteotomy with Pes Anserinus Preservation and Insertion of Bone Substitutes

Long-Term Outcomes and Prognostic Factors of Medial Open Wedge High Tibial Osteotomy for Medial Compartment Knee Osteoarthritis or Osteonecrosis

Background/Objectives: Medial open wedge high tibial osteotomy (MOWHTO) has led to favorable clinical results since the introduction of locking plates. Surgical indications, techniques, and postoperative alignment are crucial for achieving favorable clinical outcomes. This study analyzed the clinical outcomes of patients after >5 years of post-MOWHTO follow-up to identify the influential factors. Methods: Thirty-nine patients (48 knees) underwent MOWHTO for medial compartment knee osteoarthritis or -necrosis and were followed up for >5 years. The targeted postoperative % mechanical axis (%MA) was 62.5% (Fujisawa point). The Japanese Orthopaedic Association (JOA) Knee Disease Outcome Criteria score; Kellgren-Lawrence classification; hip-knee-ankle, medial proximal tibial, mechanical lateral distal femoral, and joint line convergence angles (JLCA); and %MA were evaluated preoperatively, at implant removal, and at the final follow-up. Total knee arthroplasty (TKA) was the survival endpoint. Uni- and multivariate analyses were performed to identify the factors influencing survival rates. Results: The mean JOA score improved from preoperative to implant removal and was sustained at 102 months. Four of the 48 knees required TKA, resulting in a 10-year survival rate of 82%. Body mass index, preoperative JLCA, and Δ%MA influenced the post-MOWHTO survival rate. The Δ%MA was significantly greater in the group with a %MA < 62.5% at implant removal. Conclusions: MOWHTO with a target %MA of 62.5% yielded favorable long-term outcomes. Additionally, preoperative obesity and high joint instability negatively influenced post-MOWHTO survival. Furthermore, a postoperative %MA of < 62.5% is associated with difficulty maintaining stable alignment and an increased risk of conversion to TKA.

Biomechanical effects of LCWHTO vs. MOWHTO on medial meniscus posterior root repair: a finite element analysis

Whether isolated high tibial osteotomy (HTO) or HTO combined with medial meniscus posterior root (MMPR) repair is the optimal surgical treatment of MMPR tears remains controversial. This study compared the biomechanical effects of isolated HTO versus MMPR repair combined with medial open wedge HTO (MOWHTO) or lateral closed wedge HTO (LCWHTO) using finite element analysis (FEA). In this study, the MRI and CT data of the knee joint were used to create an FEA model. MOWHTO and LCWHTO simulations adjusted the mechanical axis to the Fujisawa point, with MMPR conditions simulated as intact, tear, or repaired. The ankle center was fixed and a 1000 N force was applied to the knee. In the LCWHTO models, the posterior tibial slope (PTS) decreased, whereas it increased in the MOWHTO models. Changes in the PTS following HTO influenced the stress distribution in the MMPR. HTO combined with MMPR repair showed a reduction in the maximum contact stress by 5.4-11.4% and increased contact area by 29.5-41.0% in the medial knee compartment relative to isolated HTO. This study demonstrated that MMPR repair combined with LCWHTO would be more protective against stress loading in the MMPR than MMPR repair combined with MOWHTO or isolated HTO.

The effect of frontal plane osteotomy angle on lateral cortex fracture in medial open wedge high tibial osteotomy procedure

BACKGROUND

Precise high tibial osteotomy is crucial, especially for middle-aged individuals with medial compartment arthritis, aiming to prevent complications like lateral cortex fractures. This study explores how frontal plane osteotomy inclination impacts lateral cortex fractures during medial open-wedge high tibial osteotomy.

METHODS

Using finite element analysis, tibia models underwent osteotomies at angles of 10°, 13°, 16°, 19°, and 22°, forming five models. Forces from 5 N to 75 N were applied incrementally, recording bone stresses (MPa) at the lateral hinge, angle changes (°) along the osteotomy line, and gap distances (mm).

RESULTS

Models with higher frontal inclination showed increased gap distances under identical forces. For instance, at 5 N force, the 10° inclination model displayed a correction angle of 0.28° and a 1.43 mm gap, while the 22° model had a correction angle of 0.35° and a 1.37 mm gap. Under 75 N force, the 10° model had a correction angle of 10.81° and a 14.02 mm gap, while the 22° model had a correction angle of 16.86° and a 19.31 mm gap.

CONCLUSION

The osteotomy starting point's distance from the joint doesn't significantly impact final stress on the lateral cortex when the same gap distance is achieved. However, in cases requiring a higher degree of correction, we can say that the surgeon can achieve the result with less resistance by keeping the osteotomy starting point more distal to the joint line.

Comparative biomechanical analysis of tibial posterior slope in medial open wedge high tibial osteotomy vs. distal tuberosity osteotomy with and without anterior-posterior screw: a study using porcine tibia

Purpose While increased posterior tibial slope (PTS) is a concern post-medial open wedge high tibial osteotomy (MOWHTO), the ability of distal tuberosity osteotomy (DTO) to maintain postoperative PTS after cyclic loading remains unverified. This study aims to determine whether PTS alterations significantly differ between DTO and MOWHTO following cyclic loading.

METHODS

Biomechanical evaluations were conducted on thirty porcine tibias using MOWHTO and DTO, with and without an anterior-posterior (AP) screw. To investigate PTS changes, cyclic testing was carried out for MOWHTO and DTO. Displacement along the mechanical axis during cycles 10th, 100th, 500th, 1000th, 1500th and 2000th, variations in anterior and posterior gaps after 2000 cycles and increased PTS after 2000 cycles, were compared across the three groups. The displacement was evaluated by repeated-measures analysis of variance (ANOVA), and changes in AG and PG and increased PTS were evaluated by one-way ANOVA. The sample size for α and β errors were <0.05 and <0.20, and the effect size was 0.60 for one-way ANOVA and 0.46 for repeated-measures ANOVA.

RESULTS

There were no significant differences in displacement and anterior gap changes among the groups. A significant difference was observed in the posterior gap changes (P < 0.001) and increased PTS (P = 0.013) among the groups. Post hoc analysis indicated substantial disparities between MOWHTO and DTO without the AP screw (P = 0.035), as well as between MOWHTO and DTO with the AP screw (P = 0.021) concerning the increased PTS.

CONCLUSION

After cyclic loading, MOWHTO exhibited a notably smaller PTS change than DTO regardless of the presence of an AP screw.

Comparison of the indications for high tibial osteotomy and double-level osteotomy for the correction of diverse lower-leg deformities in an Asian population with medial compartment osteoarthritis: a retrospective observational study

PURPOSE

Double-level osteotomy (DLO) for knee osteoarthritis is becoming increasingly popular to achieve superior anatomical correction. This study aimed to compare the indication for open-wedge high tibial osteotomy (OWHTO) and DLO and to investigate preoperative bone morphology.

METHODS

Data of 166 knees treated with osteotomy were evaluated. The weight-bearing line ratio, mechanical lateral distal femoral angle (mLDFA), and mechanical medial proximal tibial angle (mMPTA) were measured. Bone deformity assessment and osteotomy simulation were conducted. Normal values of mLDFA and mMPTA were defined as 85-90°. Bone deformity was classified into four patterns: femoral, tibial, both, and no deformity. Simulation was performed to achieve a postoperative weight-bearing line ratio of 62%. Distal femoral osteotomy (DFO) or OWHTO was performed to achieve an mLDFA of 85° or mMPTA of up to 95°. If the postoperative parameter remained outside the correctable limit, DLO was performed. Cases were classified according to the corrective surgery performed, and those that could not be corrected after DLO were classified into the uncorrectable group.

RESULTS

Femoral, tibial, both, and no deformities were observed in 14.2%, 37.8%, 10.7%, and 33.9% of cases, respectively. No cases were classified into the DFO group; however, 53.6%, 38.1%, and 8.3% were classified into the OWHTO, DLO, and uncorrectable groups, respectively.

CONCLUSION

Bone deformity differed among cases, and only one-third had tibial deformity. OWHTO and DLO were indicated in approximately 50% and 40% of cases, respectively. Our study results reinforce the importance of evaluating leg morphology before surgical planning to achieve acceptable alignment.

Medial opening wedge high tibial osteotomy for the treatment of medial unicompartmental knee osteoarthritis: A state-of-the-art review

Medial unicompartmental knee osteoarthritis is a common condition that is frequently associated with significant pain and dysfunction. Medial opening wedge high tibial osteotomy (MOWHTO) offers a unique opportunity to preserve the knee joint and potentially alter the course of the degenerative process. Recent advances in this field of surgery have enabled surgeons to perform a MOWHTO in a safe, reliable and reproducible manner. This state-of-the-art review highlights the most important advances in the field of MOWHTO. Key concepts related to patient selection, pre-operative planning, surgical accuracy and patient outcome are considered. The importance of an individualized approach is emphasized and its influence on the future direction of the procedure is discussed.

A Review on Polymers for Biomedical Applications on Hard and Soft Tissues and Prosthetic Limbs

In the past decades, there has been a significant increase in the use of polymers for biomedical applications. The global medical polymer market size was valued at USD 19.92 billion in 2022 and is expected to grow at a CAGR of 8.0% from 2023 to 2030 despite some limitations, such as cost (financial limitation), strength compared to metal plates for bone fracture, design optimization and incorporation of reinforcement. Recently, this increase has been more pronounced due to important advances in synthesis and modification techniques for the design of novel biomaterials and their behavior in vitro and in vivo. Also, modern medicine allows the use of less invasive surgeries and faster surgical sutures. Besides their use in the human body, polymer biomedical materials must have desired physical, chemical, biological, biomechanical, and degradation properties. This review summarizes the use of polymers for biomedical applications, mainly focusing on hard and soft tissues, prosthetic limbs, dental applications, and bone fracture repair. The main properties, gaps, and trends are discussed.

Effect of limb alignment correction on medial meniscus extrusion under loading condition in high tibial osteotomy

Background

This study aimed to investigate the effect of high tibial osteotomy (HTO) on medial meniscus extrusion (MME) and the association between the changes in limb alignment and MME under weight-bearing (WB) conditions after HTO.

Methods

We included 17 patients with knee osteoarthritis (OA) who underwent HTO. MME was evaluated using ultrasonography in supine and unipedal standing positions. Knee alignment was evaluated radiographically using WB, whole-leg radiographs with the hip-knee-ankle angle (HKAA), percentage of the mechanical axis (%MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). All measurements were performed serially at four time points: preoperative and 3, 6, and 12 months postoperative. Clinical outcomes were assessed by knee injury and osteoarthrosis outcome score (KOOS) and visual analogue scale (VAS) value for pain.

Results

Mean MME in the WB position was significantly greater than that in the supine position in the preoperative condition; however, MME in both supine and WB positions was significantly lowered postoperatively. The ΔMME, difference of MME between supine and WB positions, was significantly lowered postoperatively and maintained for up to 1 year. MME change in the WB position between preop and postoperative conditions was significantly correlated with change in HKAA and %MA at 1 year postoperative. KOOS and VAS score were significantly improved after HTO.

Conclusions

HTO correcting varus alignment can decrease MME in WB position and minimise the change in MME between supine and WB positions. The changes in MME after HTO were correlated with changes in the mechanical alignments.

Incidence and risk factors for lateral hinge fractures in medial opening wedge high tibial osteotomy and medial opening wedge distal tibial tuberosity osteotomy

BACKGROUND

The aims of this study were (1) to compare the incidence of lateral hinge fractures (LHFs) in medial opening-wedge high tibial osteotomy (OWHTO) and medial opening-wedge distal tibial tuberosity osteotomy (DTO), and (2) to investigate the risk factors for LHFs. The incidence of LHFs was hypothesized to be higher in the DTO group than the OWHTO group. The DTO procedure is also a risk factor for LHFs.

METHODS

A total of 167 knees that underwent OWHTO (n = 65) and DTO (n = 102) were subjected to propensity score matching for the comparison of the groups. The matched variables were sex, preoperative hip-knee-ankle (HKA) angle, and preoperative medial proximal tibial angle. Forty-one matched pairs were enrolled for comparative analysis. Logistic regression analysis was performed to investigate risk factors for LHFs.

RESULTS

The incidence of LHFs was not significantly different between the groups (34.1% vs. 26.8%, respectively; p = 0.631). Logistic regression analysis showed that age (odds ratio: 1.074, 95% confidence interval (CI): 1.020-1.131, p = 0.007), BMI (odds ratio: 1.150, 95% CI: 1.049-1.260, p = 0.003), and preoperative HKA angle (odds ratio: 1.150, 95% CI: 1.049-1.260, p = 0.035) were significant risk factors for LHFs. The difference in surgical technique between OWHTO and DTO was not a risk factor for LHFs (p = 0.204).

CONCLUSIONS

The incidence of LHFs is similar in DTOs and OWHTOs, and the DTO procedure is not a risk factor for LHFs.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

The gap height in open wedge high tibial osteotomy is not affected by the starting point of the osteotomy

INTRODUCTION

In open-wedge high-tibial-osteotomy (OWHTO), most surgeons use a preoperative planning software and realise that they should match the intraoperative alignment correction with the preoperative plan. We aimed to determine whether there is a difference in osteotomy gap height when starting the OWHTO either 3 or 4 cm distal to the joint line. This should help to clarify whether the osteotomy starting point must exactly match the preoperative planning.

METHODS

25 patients with constitutional varus alignment were planned for OWHTO. Long-leg-standing-radiographs and mediCAD-software were used. Osteotomy was planned to a neutral Hip-Knee-Ankle angle (HKA) of 0°. The osteotomy-starting-point was either 3 or 4 cm distal to the medial joint line. The following angles were compared: mechanical medial proximal tibial angle (mMPTA), mechanical lateral distal femoral angle (mLDFA), joint line conversion angle (JCA), mechanical Tibio-Femoral angle (mTFA) or Hip Knee Ankle (HKA) angle.

RESULTS

25 Patients (18 males, 7 females) had a mean age of 62 ± 16.6 years and showed a varus-aligned leg-axis. The HKA was - 5.96 ± 3.02° with a mMPTA of 82.22 ± 1.14°. After osteotomy-planning to a HKA of 0°, the mMPTA was 88.94 ± 3.01°. With a mean wedge height of 8.08 mm when locating the osteotomy 3 cm and a mean wedge height of 8.05 mm when locating the osteotomy 4 cm distal to the joint-line, there was no statistically significant difference (p = 0.7).

CONCLUSION

When performing an OWHTO aiming towards the tip of the fibula, the osteotomy starting point does not need to exactly match the planned starting-location of the osteotomy. A starting-point 1 cm more distal or proximal than previously determined through the digital planning does not alter the size of the osteotomy gap needed to produce the desired amount of correction.

Femoral-varus tibial-valgus osteotomy (FVTVO) for neutrally-aligned knee osteoarthritis with severe joint line obliquity enables return to sports activities: A case series study

Background

Re-alignment surgeries for uni-compartmental knee osteoarthritis, such as high tibial osteotomy (HTO) for varus knees or distal femoral osteotomy (DFO) for valgus knees, are recognized as standard strategies. However, the treatment strategy has not been established for patients with a neutrally-aligned osteoarthritic knee with severe joint line obliquity (JLO) owing to the combination of a valgus femur and a varus tibia; i.e., type II coronal plane alignment of the knee (CPAK). total knee arthroplasty (TKA) can be an option for CPAK type II-aligned osteoarthritis in older inactive patients. Here, we hypothesized that joint line horizontalization by femoral-varus tibial-valgus osteotomy (FVTVO), which may reduce the shear stress induced by JLO, could be a treatment option for CPAK type II-aligned osteoarthritis in young active patients who wish to return to sports (RTS) activity. Our aim in this study was to evaluate the postoperative results of FVTVO with RTS.

Methods

Our indications for FVTVO are as follows: JLO >5°; mechanical medial proximal tibial angle (mMPTA) < 87°; mechanical lateral distal femoral angle (mLDFA) < 87°; typical osteoarthritis patterns for CPAK type II on magnetic resonance images, namely osteoarthritic change of the lateral tibial spine, medial slip of the femur, and/or lateral meniscal extrusion from the lateral femoral condyle; and flexion contracture <10°. We enrolled patients who wished to RTS and who had a pre-symptom Tegner score ≥5 and had completed at least a 1-year follow-up. For FVTVO, closed-wedge DFO was performed in all femurs; both closed-wedge HTO and open-wedge HTO were used in the tibia, depending on the situation. Range of motion exercises began on the first postoperative day, and full weight-bearing was permitted 6 weeks postoperatively. Jogging was permitted 3 months postoperatively after confirming bone union, and patients could gradually return to their sports activity 6-12 months' postoperatively. The Japanese Orthopaedic Association (JOA) score and knee flexion range were assessed preoperatively and at the last follow-up. Tegner activity scale scores were assessed presymptom, preoperatively, and at the last follow-up. The hip-knee-ankle (HKA) angle, JLO, mMPTA, and mLDFA were evaluated radiologically, and meniscal extrusions, osteoarthritic change, and/or bone marrow edema were assessed on magnetic resonance images.

Results

One man and two women were included in this case series. Two were competitive athletes and one was a mountain climber. The patients' ages were 69, 46, and 57 years (Case 1, 2, and 3, respectively). All patients' CPAK type was converted from type II to type V; i.e., neutral-aligned knee with a neutral joint line, postoperatively. All patients returned to their presymptom sports activity level by the final follow-up. The presymptom/preoperative/final follow-up Tegner scale in Case 1, 2, and 3 were 6/1/6, 5/2/5, and 7/3/7, respectively.

Conclusion

Joint line horizontalization by FVTVO for patients with a neutral-aligned knee with severe JLO provided highly satisfactory clinical results and successfully led to RTS.

Flexion Contracture in Knee Osteoarthritis Can Be Fully Eliminated by Hybrid Closed Wedge High Tibial Osteotomy Using a Reduction-Insertion-Compression Handle

In conventional closed-wedge high tibial osteotomy (CWHTO) with preservation of the medial hinge, flexion contracture cannot be improved because of the two-dimensional correction. Conversely, in hybrid CWHTO, for which the name is derived from a hybrid of the lateral closing and medial opening, the medial cortex is intentionally disrupted. The medial hinge disruption enables three-dimensional correction, which helps eliminate flexion contracture by decreasing posterior tibial slope (PTS). The fine adjustment of the anterior closing distance and thigh-compression technique further facilitates PTS control. In this study, we describe the use of the Reduction-Insertion-Compression Handle (RICH), which maximizes the benefits of hybrid CWHTO. This device permits accurate osteotomy reduction, easy screw insertion, and assists with providing sufficient compressive force at the osteotomy site, as well as the elimination of the flexion contracture. This Technical Note presents the details of using the RICH and the associated advantages and disadvantages in hybrid CWHTO for medial compartmental knee arthritis.

Proximal tibiofibular joint (PTFJ) dislocation due to Ehlers-Danlos syndrome: posterolateral open-wedge high tibial osteotomy combined with medial closed-wedge distal femoral osteotomy can correct the severe valgus deformity with a markedly increased tibial posterior slope

Ehlers-Danlos syndrome (EDS) causes joint hypermobility and joint dislocation. Since there are no reports of proximal tibiofibular joint (PTFJ) dislocation caused by EDS, little is known about the long-term course of this disease. A woman in her 40s presented with a posterolaterally depressed tibial condyle and severe valgus deformity caused by a long-standing PTFJ dislocation due to EDS. Considering the pathology, posterolateral open-wedge high tibial osteotomy (PLOWHTO) and medial closed-wedge distal femoral osteotomy were performed according to the deformity analysis. A favourable short-term clinical outcome was obtained and the PTFJ dislocation was reduced over time. Although PLOWHTO has several pitfalls, it is a logical and useful surgical technique that can help treat posterolateral dysplasia of the tibial plateau concomitant with severe valgus deformity, regardless of joint laxity, if performed with attention to pitfalls.

Around-knee osteotomy conversion for failed high tibial osteotomy: Re-correction high tibial osteotomy and additional distal femoral osteotomy may enable return to sporting activities

High tibial osteotomy (HTO) for knee osteoarthritis achieves excellent short- and long-term results. However, failure of HTO due to undercorrection or correction loss may necessitate conversion surgery. For patients with HTO failure who desire a return to sporting activities (RTS), non-prosthetic joint-preserving solutions such as conversion to around-knee osteotomies (AKO-conversion) may be more appropriate than total knee arthroplasty. The present study aimed to introduce potential non-prosthetic joint-preserving solutions for failed HTO and investigate the postoperative RTS. Among the patients who received non-prosthetic solutions for failed HTO from 2015 to 2020, this case series included those who were eager to RTS, were participating in a sporting activity with a Tegner activity scale score of ≥5 immediately before being affected by knee osteoarthritis, and had at least 2 years of follow-up. Deformity analysis for the preoperative planning of the AKO-conversion was based on the mechanical lateral distal femoral angle, joint line convergence angle, and mechanical medial proximal tibial angle. Four patients met the study inclusion criteria: two patients who underwent re-correction HTO and two who received additional distal femoral osteotomy (DFO). The average ages at primary HTO and AKO-conversion were 69.5 ± 11.8 years and 71.5 ± 10.9 years, respectively. The hip-knee-ankle angle was corrected from −2.8 ± 1.5° before conversion surgery to 3.3 ± 1.5° at 2 years after AKO-conversion. All four patients finally achieved a better sporting performance after AKO-conversion than preoperatively, and the Tegner activity scale score was improved from 2.5 ± 1.0 before AKO-conversion to 5.8 ± 0.5 at the 2-year follow-up. The duration between AKO-conversion and full RTS was 11.8 ± 6.7 months. In conclusion, two patients who underwent re-correction HTO and two who underwent additional DFO for undercorrection or correction loss after primary HTO achieved highly satisfactory clinical results, including RTS. The present findings suggest that non-prosthetic joint-preserving solutions using AKO for failed HTO should be considered as options to enable RTS.