Opening Wedge Research Articles

Intraoperative Complications in Medial Opening Wedge High Tibial Osteotomy.

Medial opening wedge high tibial osteotomy has been established for treatment of medial symptomatic knee arthrosis with varus malalignment in young and elderly but active patients. To obtain satisfactory results, it is essential for surgeons performing osteotomy to identify, prevent, and treat potential intraoperative adverse events. Lateral hinge fracture (LHF) is the most common intraoperative complication while popliteus artery injury is rare but limb-threatening. Computed tomography is the benchmark to detect LHF, the risk of which increased markedly with the opening gap larger than 11 mm. Setting the lateral hinge in a safe zone is the most important preventive measure. Medial long locking plate fixation may allow patients even with unstable hinge fractures to start early full weight bearing. Additional fixation of LHF is optional, and bone void filling is not routinely used. For protection of popliteus artery injury, flexing the knee joint is unreliable. It is paramount to place a protective retractor just behind the posterior tibial cortex toward the proximal tibiofibular joint before osteotomy, particularly in case of aberrant artery. A repertoire of surgical pearls is described in detail in this review to identify, prevent, and manage those intraoperative complications.

Risk factors for delayed bone union in opening wedge high tibial osteotomy.

The purpose of this study was to investigate the relationship between patient demographics and potential intraoperative factors and delayed bone union in opening wedge high tibial osteotomy (OWHTO). A retrospective review of 65 patients (37 females, 28 males; mean age: 60.1±10.1 years; range, 44 to 77 years) who underwent OWHTO using an angle-stable implant with beta-tricalcium phosphate gap filling between September 2016 and October 2019 was conducted. The osteotomy site was divided into five zones from the lateral hinge on anteroposterior radiographs, and we defined the zone in which bone healing was observed. The bone union area was assessed according to this definition at three, six, nine, and 12 months after surgery, and bone union was defined as union at the fourth zone or greater. A generalized estimating equations approach was employed to investigate longitudinal data pertaining to bone union area as a dependent variable. In addition, the association of bone union at six months postoperatively and predictors were evaluated using cross-sectional statistical methods. The categorical predictors included in the models were smoking, diabetes, hinge fracture, and autologous osteophyte grafting. The continuous variables included in the models were age, body mass index, opening gap width, and plate position. Smoking (odds ratio [OR]=0.478, p<0.01), large opening gap width (OR=0.941, p=0.014), and anterior plate placement (OR=0.971, p<0.01) were significantly associated with decreased bone union area. Union rate at six months in smokers was significantly lower compared to nonsmokers (16.6% and 67.8%, respectively; OR=0.10, p=0.023). Area under the curve in the receiver operating characteristic analysis for bone union at six months was 0.60 for gap width and 0.63 for plate placement. Smoking, large opening gap width, and anterior plate placement are risk factors for delayed bone union after OWHTO. Surgeons should avoid anterior placement of the plate and carefully consider other options for smokers and those who require a large correction.

Patellar height changes sequentially after medial open wedge high tibial osteotomy: Evaluation using shear wave elastography

BackgroundThis study was performed to evaluate changes in patellar tendon tissue after medial open wedge high tibial osteotomy (MOWHTO) using shear wave elastography (SWE) and to clarify the factors contributing to patellar height changes after MOWHTO. MethodsThe study cohort comprised 24 knees of 24 patients. Patellar tendon length, thickness, and elasticity were evaluated using SWE preoperatively, 2 weeks postoperatively, and 3, 6, and 12 months postoperatively. The Caton–Deschamps index (CDI) was also measured at these time points. Lower limb alignment and factors related to sequential changes in patellar height were evaluated. ResultsThe CDI was significantly different between preoperatively and 2 weeks postoperatively and between 2 week postoperatively and 3, 6, and 12 months postoperatively (p < 0.05 for all) The patellar tendon length at 12 months postoperatively was significantly shorter than that at 2 weeks postoperatively. The postoperative patellar tendon thickness was thicker than preoperative patellar tendon at all sites. The postoperative patellar tendon thickness significantly increased from preoperatively at middle and distal sites. The only factor associated with Δpre-post2WCDI (preCDI − post2WCDI) was ΔMPTA(medial proximal tibial angle) (postoperative MPTA – preoperative MPTA) (p = 0.042). The significant predictor of Δpost2W-post12MCDI was Δpost2W-post12 M distal elasticity (p = 0.022). ConclusionPatellar height changed sequentially after MOWHTO. The factors that caused patellar height change were related to the change in patellar tendon quality after OWHTO.

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

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. 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. 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. 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 III.

Osteotomy combined with anterior cruciate ligament reconstruction for anterior cruciate ligament injury and biplanar deformity.

It has been confirmed that the increased posterior tibial slope over 12 degrees is a risk factor for anterior cruciate ligament injury, and varus deformity can aggravate the progression of medial osteoarthritis. To evaluate the efficacy of modified high tibial osteotomy (HTO) and anterior cruciate ligament reconstruction (ACLR) in the treatment of anterior cruciate ligament (ACL) injuries with varus deformities and increased posterior tibial slope (PTS) based on clinical and imaging data. The patient data in this retrospective study were collected from 2019 to 2021. A total of 6 patients were diagnosed with ACL injury combined with varus deformities and increased PTS. All patients underwent modified open wedge HTO and ACLR. The degree of correction of varus deformity and the PTS was evaluated by radiography and magnetic resonance imaging. All 6 patients (6 knee joints) were followed up for an average of 20.8 ± 3.7 months. The average age at surgery was 29.5 ± 3.8 years. At the last follow-up, all patients resumed competitive sports. The International Knee Documentation Committee score increased from 50.3 ± 3.1 to 87.0 ± 2.8, the Lysholm score increased from 43.8 ± 4.9 to 86 ± 3.1, and the Tegner activity level increased from 2.2 ± 0.7 to 7.0 ± 0.6. The average movement distance of the tibia anterior translation was 4.8 ± 1.1 mm, medial proximal tibial angle (MPTA) was 88.9 ± 1.3° at the last follow-up, and the PTS was 8.4 ± 1.4°, both of which were significantly higher than those before surgery (P < 0.05). Modified open wedge HTO combined with ACLR can effectively treat patients with ACL ruptures with an associated increased PTS and varus deformity. The short-term effect is significant, but the long-term effect requires further follow-up.

Resection of 4th-5th Metacarpal Synostosis and Fascial Interposition for Creation of a Functional Grip /Pinch in the Apert Hand.

The 4th-5th metacarpal synostosis, present in over 80% of Apert hands, flattens the metacarpal arch, restricts metacarpal descent, may prevent opposition of border rays, and combined with symphalangism, negates any functional flexion. Ironically, the fifth ray including the digit is the most intact finger within the hand. Restoration of both position and mobility with arthroplasty changes the cardinal plane of flexion and enables both pinch and grip in these compromised hands. This report summarizes the evolution of our technique over five decades. In a cohort of 184 Apert patients (368 hands) the presence, anatomy, and level of the metacarpal synostosis with a classification was determined. The present technique consists of incision along ulnar border of hand, wide excision of the skeletal coalition, release of dorsal structures, soft tissue interposition (with cadaveric fascia lata graft) with the fifth metacarpal flexed and supinated. During the past two decades the fascia was also wrapped around the fifth metacarpal in a subperiosteal plane. No fixation is needed. The arthroplasty was commonly combined with a thumb lengthening procedure, such as opening wedge osteotomy plus autogenous bone graft at 2-6 years or distraction lengthening and bone graft at 11-13 years old. Silicone blocks, silicone sheeting, and autogenous tendon were also used as interpositions early in our experience were not included. Data was generated over a 46 period and consisted of clinical and operative records, serial molds, serial X-rays, and OT records. Follow-up ranged from 3 to 44 years. 80% of the hands (N=147 patients) had bilateral 4-5th metacarpal synostoses, the extent of which correlated with the Apert hand classification3. In 72 patients (144 hands) the synostosis was resected and cadaveric fascia interposed. The 7 hands that had silicone blocks, silicone sheets, or tendon interposition were not included in the final results. Synostosis refusion occurred in 38 hands, all of which were performed early in the series and under the age of 6 years. Despite refusion, the position of the 5th digit was improved and the flat transverse arch tin a more curved or cupped posture. Eight of refused synostoses were re-released, usually in conjunction with thumb distraction lengthening. Distance between the opposing border rays was always improved and a new grip and pinch mechanism created. Aggressive ostectomy of synostosis and fascial interposition places the ulnar side of the hand in a much more functional position. In conjunction with thumb lengthening, opposition between the thumb and fifth finger becomes a clinical reality in Apert children who are born with diminutive thumbs and minimal interphalangeal joint motion.

The Osteotomy Gap Filling Rate of Multiple Time Points After Medial Opening Wedge High Tibial Osteotomy Without Bone Graft

BackgroundThe purpose of the present study was to analyze osteotomy gap filling of multiple time points until 2 years post-medial opening wedge high tibial osteotomy (MOWHTO). The absolute value of gap filling and postoperative changes relative to the preoperative void osteotomy gap were evaluated using computed tomography (CT) at each time point. MethodsData of 30 patients who underwent MOWHTO between September 2019 and July 2021 were retrospectively analyzed. Surgical procedures without bone grafts were performed; a standardized rehabilitation protocol was implemented. The osteotomy gap filling rate was measured using computed tomography scans at the immediate postoperative period and at 6, 12, and 24 months after surgery. Statistical analyses were performed to assess changes over time. ResultsThe osteotomy gap filling rate showed a significant continuous increase after MOWHTO, reaching 45.2% at 6 months and 66.7 and 84.4% at 1 and 2 years, postoperatively, respectively. The most substantial increase occurred within the initial 6 months, thus indicating a critical period for bone healing. ConclusionsThe osteotomy gap filling rate showed a significant and gradual increase from immediately after surgery to 2 years after MOWHTO without bone grafting, the greatest of which was achieved in the initial 6-month period. Therefore, this study may be helpful for planning postoperative rehabilitation, including the extent of weight-bearing load and the period of crutch use. Study designCase series; Level of Evidence IV.

Open wedge high tibial osteotomy alters patellofemoral joint kinematics: A multibody simulation study.

Changes in lower limb alignment after open-wedge high tibial osteotomy (owHTO) influence joint kinematics. The aim of this study was to investigate the morphological and kinematic changes of the knee joint, in particular the patellofemoral joint, using a multibody simulation model. OwHTO with an open tibial wedge of 6-12 mm (1 mm intervals) was virtually performed on each of 13 three-dimensional (3D) computer-aideddesign models (CAD models) derived from computer tomography scans of full-leg cadaver specimens. For each owHTO, an individual biomechanical simulation model was built and knee flexion from 5° to 100° was simulated using a multibody simulation model of the native knee. Morphologic and alignment parameters as well as tibiofemoral and patellofemoral kinematic parameters were evaluated. Almost linear changes in tibial tuberosity trochlea groove(TT-TG) (0.42 mm/1 mm wedge height) were observed which led to pathological values (TT-TG > 20 mm) in 3 out of 13 knees. Furthermore, a 6 mm increase in osteotomy wedge height increased lateral patellofemoral rotation by 0.8° (range: 0.39° to 1.11°) and led to a lateral patellar translation of 0.8 mm (range: 0.37-3.11 mm) on average. Additionally, valgisation led to a medial translation of the tibia and a decrease in the degree of tibial internal rotation during knee flexion of approximately 0.3°/1 mm increase in osteotomy wedge height. The increase in TT-TG and the biomechanical effects observed influence patellofemoral tracking, which may increase retropatellar pressure and are potential risk factors for the development of anterior knee pain.

Clinical outcomes of guider-assisted osteotomy compared to conventional pendulum-saw osteotomy in open wedge high tibial osteotomy: a propensity score-matched cohort study

PurposeWe developed a novel guider-assisted osteotomy (GAO) procedure to improve the safety of open wedge high tibial osteotomy (OWHTO) and aimed to compare its efficacy and complications with the conventional pendulum-saw osteotomy (PSO).MethodsThis is a retrospective cohort study of patients undergoing either GAO or PSO procedure in the OWHTO to treat varus knee osteoarthritis, who had a minimum of 2 years of follow-up. Patients were propensity score matched (PSM) in a 1:1 ratio based on demographic and clinical data with a caliper width of 0.02. The outcomes assessed involved the hospital for special surgery (HSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and the Intraoperative and postoperative complications.Results199 patients were included in each group after PSM. The mean duration of follow-up was 38.3 ± 8.9 months. The GAO group had a shorter operation duration (104.5 ± 35.7 vs. 112.1 ± 36.0 min, p = 0.027) and fewer times of intraoperative fluoroscopy (4.2 ± 1.4 vs. 6.0 ± 1.4, p < 0.001). At the last follow-up, clinical scores for knee achieved significant improvements in both GAO and PSO groups: HSS (67.5 ± 10.5 vs. 90.2 ± 7.0, p < 0.001; 69.4 ± 8.2 vs. 91.7 ± 6.8, p < 0.001) and WOMAC (65.7 ± 11.6 vs. 25.2 ± 10.4, p < 0.001; 63.3 ± 12.2 vs. 23.8 ± 9.5, p < 0.001). However, no significant difference was observed between groups for any measures (p > 0.05). In addition, the intraoperative complications (0.5% vs. 3.5%, p = 0.068) and the postoperative bone delayed union and nonunion (1.0% vs. 4.5%, p = 0.032) were marginally or significantly reduced in the GAO versus PSO group.ConclusionGAO demonstrates improvements in intraoperative radiation exposure and complications, with comparable short-term efficacy to PSO, and could be considered a viable alternative in clinical practice.

Low-density lipoprotein cholesterol-to-lymphocyte count ratio (LLR) is a promising novel predictor of postoperative new-onset deep vein thrombosis following open wedge high tibial osteotomy: a propensity score-matched analysis

BackgroundThe association of low-density lipoprotein cholesterol (LDL-C) and lymphocyte counts with the development of deep vein thrombosis (DVT) has been demonstrated in many fields but remains lacking in open wedge high tibial osteotomy (OWHTO). This study aimed to assess the predictive value of LDL-C to lymphocyte count ratio (LLR) in screening for postoperative new-onset DVT.MethodsClinical data were retrospectively collected from patients who underwent OWHTO between June 2018 and May 2023. The limited restricted cubic spline (RCS) was conducted to evaluate the nonlinear relationship between LLR and the risk of postoperative new-onset DVT. The receiver operating characteristic (ROC) curves were plotted and the predictive value of biomarkers was assessed. After adjusting for intergroup confounders by propensity score matching, the univariate logistic regression was applied to assess the association between LLR and DVT.Results1293 eligible patients were included. RCS analysis showed a linear positive correlation between LLR and the risk of DVT (P for overall = 0.008). We identified LLR had an area under the curve of 0.607, accuracy of 74.3%, sensitivity of 38.5%, and specificity of 80.7%, and LLR > 1.75 was independently associated with a 1.45-fold risk of DVT (95% CI: 1.01–2.08, P = 0.045). Furthermore, significant heterogeneities were observed in the subgroups of age, BMI, diabetes mellitus, hypertension, Kellgren-Lawrence grade, the American Society of Anesthesiologists (ASA) score, and intraoperative osteotomy correction size.ConclusionLLR is a valuable biomarker for predicting postoperative new-onset DVT in patients with OWHTO, and routine screening is expected to yield positive benefits.

Learning curves for high tibial osteotomy using patient-specific instrumentation: a case control study.

Three-dimensional (3D) planning and Patient Specific Instrumentation (PSI) can help the surgeon to obtain more predictable results in Medial Opening Wedge High Tibial Osteotomy (mOW-HTO) than the conventional techniques. We compared the accuracy of the PSI and standard techniques and measured the learning curve for surgery time and number of fluoroscopic shots. We included the first 12 consecutive cases of mOW-HTO performed with 3D planning and PSI cutting guides and the first 12 non-supervised mOW-HTO performed with the standard technique. We recorded surgery time and fluoroscopic time. We calculated the variation (Δ delta) between the planned target and the postoperative result for Hip Knee Ankle Angle (HKA), mechanical medial Proximal Tibia Angle (MPTA), Joint Line Convergence Angle (JLCA) and tibial slope (TS) and compared it both groups. We also recorded the complication rate. We then calculated the learning curves for surgery time, number of fluoroscopic shots, Δ from target in both groups. CUSUM analysis charts for learning curves were applied between the two groups. Mean surgical time and mean number of fluoroscopic shots were lower in PSI group (48.58±7.87 vs. 58.75±6.86 min; p=0.034 and 10.75±3.93 vs. 18.16±4.93 shots; p<0.001). The postoperative ΔHKA was 0.42±0.51° in PSI vs. 1.25±0.87° in conventional, p=0.005. ΔMPTA was 0.50±0.67° in PSI vs. 3.75±1.48° in conventional, p<0.001; ΔTS was 1.00±0.82° in PSI vs. 3.50±1.57° in conventional, p<0.001. ΔJLCA was 1.83±1.11° in PSI vs. 4±1.41° in conventional, p<0.001. The CUSUM analysis favoured PSI group regarding surgery time (p=0.034) and number of shots (p<0.001) with no learning curve effect for ΔHKA, ΔMPTA, ΔJLCA and ΔTS. PSI cutting guides and 3D planning for HTO are effective in reducing the learning curves for operation time and number of fluoroscopic shots. Accuracy of the procedure has been elevated since the first cases.

Application of Autologous Bone Graft versus Non Grafting in Medial Opening Wedge High Tibial Osteotomy Less than 14 mm: A Systematic Review and Meta-Analysis

Abstract Background Unicompartmental Knee osteoarthritis KOA due to varus malalignment is increased in young active patients which occurs predominantly in the medial compartment. Aim of the Work The objective of this study to compare MOWHTOs with autologous bone graft and without bone graft (wedge space mean less than 14 mm) in treatment of unicompartmental KOA and varus malalignment of the knee to determine which is better in decision-making according to outcomes. Patients and Methods Studies that matched the inclusion criteria were included in this meta-analysis. participants with medial compartmental knee osteoarthritis and varus malalignment were shown in the investigation. The age of the participants was unrestricted. Plate as a fixation method was the only option regardless of plate type. During 2000 and 2021, a research study of internet databases (Egyptian Universities Research, Medline, PubMed, Cochran library, medical journals) was conducted. Following that, the references from the user research were examined, and specialists were approached for assistance in locating other papers. Two independent reviewers extracted data separately and cross-checked it. Results The Knee Society Knee score (KSKS) and Knee Society Function score (KSFS) are most commonly used for the assessment of the knee joint reveled that there is no statically significant difference between bone graft vs non graft. Regarding this systematic review the radiological outcomes, the clinical bone union and the full weight bearing movement, are rendering any statistical analysis meaningless. Regarding complications presented, there was a similar tendency for complication rate when compared according to grafting or non- grafting. The use of autograft accelerates radiographic healing of the osteotomy gap after OWHTO while shorten the union time but confers no advantages in terms of functional or patient elated out comes at 3 or 12 months postoperatively. Conclusion MOWHTO can be performed without a graft with less operative time and avoiding graft harvest comorbidity with similar clinical and radiological results regarding bone union and posterior tibial slope alteration and knee scores.

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.

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. 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. 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 11min between the groups, being lower in the allograft group (Allograft: 65.4 ± 15.1min vs. Autograft: 76.3 ± 15.2min; p = 0.02). 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. U1111-1280-0637 1 December 2022, retrospectively registered.

Paper 34: Supratubercle Anterior Closing Wedge Osteotomy: No Change in Patellar Height, Compared to Decreased Height for Medial Opening Wedge Proximal Tibial Osteotomy, and Significant Decreases in Anterior Tibial Translation at Six Months Postoperatively

Objectives: The purpose of this study was to radiographically assess changes in 1) patellar height, 2) anterior tibial translation (ATT), and 3) posterior tibial slope following supratubercle ACW-PTO and to compare changes in patellar height to a cohort of medial opening proximal tibial osteotomies (MOW-PTO). Methods: Patients who underwent supratubercle ACW-PTO by a single surgeon from July 2019-February 2023 were included. Institutional Review Board approval was obtained for this study. Radiographic assessment at four time points (preoperative, postoperative day 1, 3 months and 6 months) of patellar height (via the Caton Dechamps and Insall Salvati ratios), posterior tibial slope, and anterior tibial translation of the lateral tibial plateau relative to the lateral femoral condyle was completed. A comparison cohort of patients undergoing MOW-PTO was included for comparison of patellar height. Results: Patellar height averages ( n=16) after ACW-PTO using the Caton-Deschamps ratio (Figure 1) demonstrated a significant increase in patellar height on postoperative day 1 ( p=0.004), but were not significantly different at 3 and 6 months postoperatively (Table 2). Conversely, averages of patellar height after MOW-PTO ( n=28) demonstrated no difference on postoperative day 1, but then was significantly decreased by 6 months postoperatively ( p=0.005) (Table 1). There was a significant difference between the closing and opening-wedge cohorts when comparing the difference in patellar height using the CD ratio between preoperative and 6 months ( p=0.011). Anterior tibial translation in the ACW-PTO cohort was significantly decreased by an average of 9.0 mm from preoperative to postoperative values ( p&lt;&lt;0.001) (Figure 2). Posterior tibial slope in the ACW-PTO cohort was significantly decreased by an average of 11.8° from preoperative to postoperative values ( p&lt;&lt;0.001). Conclusions: Supratubercle ACW-PTO performed for ACL failure in the setting of increased tibial slope did not induce significant changes in patellar height postoperatively. Furthermore, following ACW-PTO there was a significant decrease in anterior tibial translation and posterior tibial slope.

Required force for distraction during medial opening wedge high tibial osteotomy may serve as a predictive indicator for lateral hinge fracture.

Medial open wedge high tibial osteotomy is a biological procedure for treating unicompartmental knee osteoarthritis. The literature repeatedly highlights the significance of preserving an intact lateral hinge during this procedure. We investigated the temporal course of distraction forces during distraction at the osteotomy site, aiming to quantitatively measure and analyse temporal changes in distraction forces at different distraction points for intact and fractured lateral hinges. This biomechanical study was conducted on 10 human cadavers, which were divided into two groups: one with preserved 1 cm intact lateral cortexes (ILCs) and the other with completely osteotomised fractured lateral cortexes (FLCs). An experimental setup was custom designed to facilitate the required force measurement during distraction. The distraction forces were recorded with a force gauge at 0.5-mm intervals throughout the distraction. There was a significant difference between the ILC and FLC groups in distraction forces at all points (8-15 mm). The ILC group consistently exhibited higher distraction force values, with FLC recording values ranging from 8.8% to 13.2% of ILC's. Lateral hinge fractures caused an 86.7% reduction in the initial required force for distraction, significantly impacting the force required for distraction. The ILC group displayed a linear increase in the required distraction force up to 12.5 mm of distraction, which reached 3.7 times the initial value at 12.5 mm of distraction. The FLC group had lower baseline required distraction forces, following a relatively linear trend with more limited increases. FLCs in medial opening wedge osteotomy are associated with significant reductions in the force required for distraction, and a sudden decrease in distraction force during distraction may indicate a lateral hinge fracture. Force measurement devices for use during distraction could offer valuable insights and provide surgeons with immediate warnings for LHFs. Level IV.

Paper 32: Leg Length Changes Following Distal Femoral Osteotomy: Validation of a Predictive Tool and Comparison of Lateral Opening Wedge and Medial Closing Wedge Techniques

Objectives: A DFO can be performed via two techniques: a lateral opening wedge (LOW) osteotomy and a medial closing wedge (MCW) osteotomy. Small case series have looked at how leg length is affected by a lateral opening wedge DFO, however, there is a lack of research comparing these leg length changes to medial closing DFO. Additionally, no studies have presented a model for predicting the leg length changes that will occur following DFO of either technique. Given that limb length differences can lead to accelerated osteoarthritis, back pain, hip pain, and other issues, being able to predict which technique can help prevent this pathology without a secondary procedure would be an important finding. Finally, the medial closing wedge osteotomy can allow for immediate weight-bearing while the lateral opening wedge does not and typically has associated cost with bone grafting. Therefore, we designed this study to validate a tool designed to predict leg length changes after distal femoral osteotomy (DFO) and compare changes following medial closing wedge (MCW) and lateral opening wedge (LOW) techniques. Methods: A collaborative retrospective review was performed of patients from Rush and Mayo Clinic databases who received a DFO and had full-length standing radiographs both pre-and postoperatively. For each preoperative radiograph, the region on the medial (for LOW) or lateral (for MCW) distal femur cortex that would be the “hinge point” during DFO was identified. The distances from the center of the femoral head to the hinge point (“A”), from the hinge point to the center of the tibial plafond (“B”), and the resultant angle at the hinge point (“α”) were measured (Figure 1). Figure 2 demonstrates the equation used to plot a graph of the predicted leg length changes corresponding to the change in α angle produced by DFO. Final leg length was calculated on postoperative radiographs, and the difference between predicted and true leg length changes was compared using paired Wilcoxon signed rank exact tests. Results: 10 MCW and 10 LOW patients were included. For both LOW (n=10) and MCW (n=10) osteotomies, the predicted leg length change was equivalent to the true change measured on postoperative radiographs (LOW P=0.16; MCW P=0.85). LOW DFO’s had 5.10 ± 2.77 mm (range: 1.45-10.87 mm) of leg lengthening, compared to 2.61 ± 1.25 mm (range: 0.50-4.56 mm) of leg shortening (p&lt;0.001) for MCW (Figure 3). On average, there was 0.85 mm of lengthening (range 0.5-1.3 mm) for every 1° of mechanical axis correction with LOW DFO, compared to 0.45 mm of shortening (range: 0.1-1.4 mm) per 1° of MCW correction. Conclusions: This study presents a tool to accurately and reliably predict the leg length changes seen after both medial closing and lateral opening wedge DFO’s. Knowing what leg length changes to expect with each DFO technique is a useful tool that surgeons can utilize during surgical planning. Preoperative radiographic imaging can be used to predict leg length change following DFO with high reliability and accuracy. Surgeons can expect approximately 0.85mm of lengthening per 1° of DFO correction when performing LOW, compared to 0.45mm of shortening per 1° correction for MCW osteotomies.

Is single-stage bilateral medial opening wedge high tibial osteotomy advisable?

PurposeTo validate the safety and clinical results of single-stage bilateral versus unilateral medial opening wedge high tibial osteotomy (HTO).MethodsA propensity-matched cohort study was performed from March 2020 to March 2021 in our medical center. Data were prospectively collected. Including 34 patients who underwent single-stage bilateral medial opening HTO(SSBHTO), and 68 cases in the unilateral group. Propensity-matched ration was 2:1 based on age, sex, and body mass index using R software. Comparisons of the length of hospital stay, operative time, blood loss, postoperative adverse events, 90-day readmission rate, conversion to TKA rate, self-reported VAS and WOMAC scores were made to investigate the safety and clinical results of bilateral HTO.ResultsThe mean length of hospital stay was 7.36 ± 2.23 days for SSBHTO and 7 days (IQR, 3 days; range, 4 to 23 days) for the unilateral group (P = 0.219). The mean operative time was 144 ± 47 min for bilateral HTO and 105(37.5) mins for a unilateral OWHTO (P < 0.001). The mean blood loss was 150(100) ml for SSBHTO and 100(50) ml for unilateral OWHTO (P < 0.001). There were no significant difference of the adverse events and 90-day readmission rate between two groups. No failed HTO or conversion to knee arthroplasty were observed at the end of follow-up. VAS, pain, stiffness, and functional scores of the WOMAC scale were essentially comparable of two groups one year after surgery (P > 0.05).ConclusionsA single-stage bilateral medial opening wedge high tibial osteotomy is advisable for patients with knee osteoarthritis. Patients benefit from avoiding secondary anesthesia, postoperative complications, and substantial cost savings.Level of EvidenceTherapeutic Level III.

Improvement of absorbability, osteoconductivity, and strength of a β-tricalcium phosphate spacer for opening wedge high tibial osteotomy: clinical evaluations with 106 patients

BackgroundAn ideal synthetic spacer for medial opening wedge high tibial osteotomy (MOWHTO) has not yet been developed. The authors have developed a new β-tricalcium phosphate (β-TCP) spacer with 60% porosity (N-CP60) by modifying the micro- and macro-pore structures of a conventional β-TCP spacer (CP60) that is widely used in clinical practice. The purpose of this study was to compare the absorbability, osteoconductivity, and in vivo strength of the N-CP60 spacer with those of the CP60 spacer, when used in MOWHTO.MethodsFirst, the porosity, diameter distribution of macro- and micropores, and compressive strength of each β-TCP block were examined using methodology of biomaterial science. Secondly, a clinical study was performed using a total of 106 patients (106 knees) with MOWHTO, who were followed up for 18 months after surgery. In these knees, the N-CP60 and CP-60 spacers were implanted into 49 tibias and 57 tibias, respectively. The absorbability and osteoconductivity were radiologically evaluated by measuring the area of the implanted spacer remaining unabsorbed and assessing with the Hemert’s score, respectively. The incidence of cracking in the implanted spacers was determined using computed radiography. Statistical comparisons were made with non-parametric tests. The significance level was set at p = 0.05.ResultsThe N-CP60 and CP60 blocks had almost the same porosity (mean, 61.0% and 58.7%, respectively). The diameter of macropores was significantly larger (p < 0.0001) in the N-CP60 block than in the CP60 block, while the diameter of micropores was significantly smaller (p = 0.019) in the N-CP60 block. The ultimate strength of the N-CP60 block (median, 36.8 MPa) was significantly greater (p < 0.01) than that of the CP60 block (31.6 MPa). As for the clinical evaluations, the absorption rate of the N-CP60 spacer at 18 months after implantation (mean, 48.0%) was significantly greater (p < 0.001) than that of the CP60 spacer (29.0%). The osteoconductivity of the N-CP60 spacer was slightly but significantly higher (p = 0.0408) than that of the CP60 spacer only in zone 1. The incidence of in vivo cracking of the posteriorly located N-CP60 spacer at one month (mean, 75.5%) was significantly lower (p = 0.0035) than that of the CP60 spacer (91.2%).ConclusionsThe absorbability, osteoconductivity, and compressive strength of the new N-CP60 spacer were significantly improved by modifying the macro- and micro-pore structures, compared with the conventional CP60 spacer. The N-CP60 spacer is more clinically useful than the CP60 spacer.Trial registration numberH29-0002.

Postoperative improvement in patient-reported outcomes after neutral alignment medial open wedge high tibial osteotomy for medial compartment knee osteoarthritis in patients aged ≥70 years versus younger patients.

To compare the postoperative clinical and radiological outcomes in patients aged ≥70 years following neutral alignment medial opening-wedge high tibial osteotomy (NA-MOWHTO) for medial compartment knee osteoarthritis (KOA) to those observed in younger patients. The data of patients who underwent NA-MOWHTO for medial compartment KOA between September 2018 and June 2022 were retrospectively analysed. The patients were categorised into groups Y (<70 years) and O (≥70 years). Age, sex, Kellgren-Lawrence classification, pre- and postoperative mechanical axis, weight-bearing line ratio, medial proximal tibial angle, preoperative Tegner Activity Score and pre- and postoperative Lysholm scores were compared between the groups. Overall, 81 patients (60 and 21 in groups Y and O, respectively) who underwent NA-MOWHTO were included in this study. No significant differences were found in patient characteristics between the two groups, except for the preoperative Tegner Activity Score, which was significantly higher in group Y than in group O (3 [2-4] vs. 2 [2-2], respectively; p = 0.011). The two groups exhibited no significant differences in pre- and postoperative knee alignments. Postoperatively, Lysholm scores improved significantly in both groups without significant differences. Additionally, no correlation was found between age and pre- and postoperative Lysholm scores. The postoperative improvement following NA-MOWHTO for medial compartment KOA is comparable in patients aged ≥70 and younger. Level III, Retrospective comparative study.

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

The purpose of the European consensus was to provide recommendations for the treatment of patients with a painful degenerative varus knee using a joint preservation approach. Part II focused on surgery, rehabilitation and complications after tibial or femoral correction osteotomy. Ninety-four orthopaedic surgeons from 24 countries across Europe were involved in the consensus, which focused on osteotomies around the knee. The consensus was performed according to the European Society for Sports Traumatology, Knee Surgery and Arthroscopy consensus methodology. The steering group designed the questions and prepared the statements based on the experience of the experts and the evidence of the literature. The statements were evaluated by the ratings of thepeer-review groups before a final consensus was released. The ideal hinge position for medial opening wedge high tibial osteotomy (MOW HTO) should be at the upper level of the proximal tibiofibular joint, and for lateral closing wedge distal femoral osteotomy (LCW DFO) just above the medial femoral condyle. Hinge protection is not mandatory. Biplanar osteotomy cuts provide more stability and quicker bony union for both MOW HTO and LCW DFO and are especially recommended for the latter. Osteotomy gap filling is not mandatory, unless structural augmentation for stabilityis required. Patient-specific instrumentation should be reserved for complex cases by experienced hands. Early full weight-bearing can be adopted after osteotomy, regardless of the technique. However, extra caution should be exercised in DFO patients. Osteotomy patients should return to sports within 6 months. Clear recommendations for surgical strategy, rehabilitation and complications of knee osteotomies for the painful degenerative varus kneewere demonstrated. In Part 2of the consensus, high levels of agreement were reached by experts throughout Europe, under variable working conditions. Where science islimited, the collated expertise of the collaborators aimed at providing guidance for orthopaedic surgeons developing an interest in the fieldand highlighting areas for potential future research. Level II, consensus.