Clinical and radiological results of high tibial of osteotomy over the age of 65 are comparable to that of under 55 at minimum 2-year follow-up: a propensity score matched analysis

Age affects the osteotomy gap filling rate after biplanar medial opening wedge high tibial osteotomy without a bone graft

BACKGROUND

This study was designed to determine the relationship between age and osteotomy gap filling rate, aiming to discern the specific time period during which age exerts its impact on this process. The osteotomy gap filling rate after medial opening wedge high tibial osteotomy (MOWHTO) was assessed by evaluating the absolute value of gap filling utilizing computed tomography (CT) scan obtained at multiple time points postoperatively.

METHODS

The data of 30 patients who underwent MOWHTO between September 2019 and July 2021 were retrospectively analyzed. Computed tomography findings were used to measure osteotomy gap filling rate at 6, 12, and 24 months postoperatively. Patients were divided into two age groups (those aged ≤ 55 and > 55 years) for comparison.

RESULTS

Patients aged ≤ 55 years showed significantly greater osteotomy gap filling rate at the 6-month follow-up examination compared to that of older patients (p = 0.034). Pearson's correlation analysis revealed a negative correlation between age and osteotomy gap filling rate at 6 and 12 months postoperatively (r = -0.426, p = 0.019; r = -0.368, p = 0.046, respectively). Multiple linear regression analysis identified age as the sole predictor of osteotomy gap filling rate at 6 months postoperatively (β = -0.407, p = 0.039).

CONCLUSION

Age significantly influenced the osteotomy gap filling rate after MOWHTO. Patients aged ≤ 55 years demonstrated greater improvement in gap filling during the initial 6-month period compared to their older counterparts. These findings underscore the importance of age considerations when deciding on the indication for MOWHTO in cases of medial knee osteoarthritis in clinical practice.

STUDY DESIGN

Case series, Level of Evidence IV.

Achieving Sufficient Valgus Alignment is Essential to Ensure Low Residual Pain in Short- to Midterm Follow-up After High Tibial Osteotomy in KL Grade 4 Osteoarthritis Patients

Background

Severe osteoarthritis (OA) has been identified as a risk factor for inferior outcomes following high tibial osteotomy (HTO).

Purpose

To investigate the effectiveness of HTO in patients with advanced OA, particularly those with Kellgren-Lawrence (KL) grade 4 (KL4), and to compare clinical outcomes based on OA severity and the effect of postoperative alignment in each group.

Study Design

Cohort study; Level of evidence, 3.

Methods

A retrospective review was conducted on patients who underwent biplanar medial opening-wedge HTO from 2010 to 2022, with a follow-up period of 2 to 5 years. Patients were divided into 2 groups based on preoperative KL grades: non-KL4 and KL4. Clinical outcomes were compared using patient-reported outcome (PRO) measures: pain visual analog scale (VAS), Lysholm Knee Score, and Knee injury and Osteoarthritis Outcome Score (KOOS) between the groups. Subgroup analyses were conducted to ascertain whether outcomes differed based on postoperative weightbearing line (WBL) ratio within each group.

Results

Out of 324 patients, 141 were eligible: 110 in the non-KL4 group and 31 in the KL4 group, with a mean follow-up of 37.5 months (overall mean age, 56.9 years; mean body mass index, 26.9 kg/m2). Baseline demographics were similar between the groups. The KL4 group had more severe preoperative conditions (larger defect size and more varus). However, both groups showed significant improvements in PROs (P < .001), with no significant differences between them. In the KL4 group, patients with a postoperative WBL ratio ≥62.5% showed better scores in certain PRO measures, while other PRO data showed no significant differences (VAS: 17.1 ± 19.1 vs 33.9 ± 18.3, P = .03; KOOS Activities of Daily Living subscale: 78.7 ± 9.9 vs 69.3 ± 13.8, P = .04). In contrast, the non-KL4 group showed no difference in PROs based on WBL ratio. In the KL4 group, the final VAS was most correlated with the WBL ratio (r = -0.545; P = .002). A WBL ratio of 62.2% to 67.3% was the cutoff value to predict the achievement of low residual pain (VAS < 18; median of KL4 group) in KL4 patients.

Conclusion

HTO can yield comparable clinical outcomes in KL4 OA patients to those with lower-grade OA. However, achieving sufficient valgus alignment (WBL ratio > 62.2%-67.3%) correlates with less residual pain in the short- to midterm follow-up in high-grade OA patients.

Safe Sawing Conditions to Prevent Popliteal Artery Injury in Various Distal Femoral Osteotomies: Three-dimensional Simulation Analysis

BACKGROUND

Distal femoral osteotomy (DFO) use is increasing in popularity, and popliteal artery injury during DFO can be devastating.

PURPOSE

To determine the safe sawing angles in DFO to prevent popliteal artery injury by analyzing the artery's course and the distances from key structures within the osteotomy plane.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Three-dimensional images of the healthy popliteal artery and femur were reconstructed from computed tomography angiography scans of 27 patients, and medial and lateral closing-wedge DFO (MCW-DFO and LCW-DFO) was simulated. Specifically, after formation of the osteotomy plane that passes the designated hinge point and primary cutting start point, the plane was rotated by 5° and 10° to create the 0°, 5°, and 10° osteotomy planes. Minimal distances to the popliteal artery from the posterior cortex and posterior cortical line (dPA-PC, dPA-PCL) were measured in each osteotomy plane. A distance <10 mm was defined as "at risk." Frontal safe sawing index (FSSI), maximal safe sawing angles (MSSAs), and maximal safe osteotomy angles (MSOAs) were analyzed to evaluate the safety margin.

RESULTS

The FSSI was significantly higher in MCW-DFO than LCW-DFO across all osteotomy planes (P < .001). In MCW-DFO, FSSI decreased with higher-degree upper cuts (P < .001), while in LCW-DFO, it was maintained. The mean minimal distance to the popliteal artery from the posterior cortex ranged from 13 to 14 mm in all DFO simulations. MCW-DFO and LCW-DFO showed a decrease in dPA-PC with higher-degree cuts (P < .001), and dPA-PCL was consistently shorter than dPA-PC (P < .001). The at-risk ratio of dPA-PCL was higher than that of dPA-PC in all conditions, favoring cutting along the normal curvature of the cortex over cutting straight. The MSSA for MCW-DFO was around 5°, with no significant variation between osteotomy planes. LCW-DFO had a smaller safety margin when compared with MCW-DFO, considering the 95% confidence interval of MSSAs. However, MSOA values were higher in LCW-DFO than MCW-DFO (P < .001). The dPA-PC was correlated with height, weight, body mass index, and transepicondylar distance (P < .05).

CONCLUSION/CLINICAL RELEVANCE

The safety margin during osteotomies in various DFO scenarios may vary. When DFO is performed, it is essential to be aware of safety tips related to the course of the popliteal artery and the normal curvature of the femoral posterior cortex.

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.

Medial Meniscal Posterior Root Repairs Performed With Modified Mason-Allen Locking Stitches Are Associated With Intact but Lax Repairs in a High Proportion of Second-Look Arthroscopy Cases

PURPOSE

To investigate meniscal healing results and clinical outcomes based on healing status after root repair using modified Mason-Allen stitches with a locking mechanism from second-look arthroscopy in medial meniscal posterior root tears.

METHODS

Among patients who underwent root repair between 2018 and 2022, those who consented to undergo second-look arthroscopy 1 year after surgery were recruited. The healing condition of the repaired meniscus was evaluated based on (1) morphologic continuity between the bone bed and meniscus (intact vs non-intact) and (2) meniscal laxity at the bony attachment by probing (lax vs non-lax). Healing conditions were categorized as follows: intact and non-lax tissue (group 1), intact and lax tissue (group 2), and healing failure (group 3). Clinical scores (Lysholm score, Western Ontario McMaster Osteoarthritis Index [WOMAC] score, and Knee Injury and Osteoarthritis Outcome Score [KOOS]) and radiologic outcomes (Kellgren-Lawrence grade and medial joint space width) were evaluated preoperatively and at the final follow-up.

RESULTS

In total, 34 patients (mean age, 58.2 ± 6.1 years) were enrolled. In terms of healing conditions, intact root tissue and healing failure were observed in 33 patients (97%) and 1 patient (3%), respectively. Among those with intact root tissue, 19 patients (56%) and 14 patients (41%) showed non-lax tissue (group 1) and lax tissue (group 2), respectively. A significant improvement in clinical scores after surgery was noted in groups 1 and 2 but not in group 3. Regarding postoperative clinical scores, the mean values in group 1 were as follows: Lysholm score, 86.1 ± 8.2 (minimal clinically important difference [MCID], 5.35); WOMAC score, 12.8 ± 6.6 (MCID, 4.55); and KOOS, 22.4 ± 6.8 (MCID, 4.5). The group 1 outcomes were substantially better than those in group 2; the group 2 scores were as follows: Lysholm score, 76.8 ± 7.0 (MCID, 2.85); WOMAC score, 21.0 ± 8.3 (MCID, 4.75); and KOOS, 32.8 ± 10.0 (MCID, 6.5). Radiographically, group 1 exhibited significantly less Kellgren-Lawrence grade progression and less medial joint space narrowing than group 2.

CONCLUSIONS

Pullout repair using modified Mason-Allen stitches showed promising healing outcomes with a 97% rate of intact root healing on second-look arthroscopy. However, repairs that showed laxity were associated with significantly worse patient-reported outcome measures and higher rates of progression of osteoarthritis. Considering that 23% of the total patients refused second-look arthroscopy, the possibility of transfer bias should be considered.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Mechanical stability of the proximal tibia with different bone formations after plate removal in medial opening-wedge high tibial osteotomy: a finite element analysis

BACKGROUND

No clear agreement exists on the degree of bone formation required to remove a metal plate without correction loss after medial opening-wedge high tibial osteotomy (MOWHTO). We aimed to investigate the mechanical stability of the proximal tibia with different bone formations after plate removal in MOWHTO using finite element models and determine the extent of bone formation when the plate can be removed without correction loss.

METHODS

The MOWHTO models with 5, 10, and 15 mm opening gaps were generated. The mechanical stability of proximal tibial models with different extents of bone formation (from the lateral cortex of the osteotomy wedge to 20% (zone 1), 40% (zone 2), 50% (zone 2.5), 60% (zone 3), 70% (zone 3.5), 80% (zone 4), and 100% bone formation medially) after plate removal was analyzed using finite element analysis. Bone stress and strain and micromotion were evaluated to investigate fracture risk and bone stability, respectively, in various types of tibial models.

RESULTS

Peak von Mises stress was lower than yield strength when bone formation reached zone 3.5 (70%) or more in 5- and 10-mm osteotomy gap models, and zone 4 (80%) or more in a 15-mm gap model. Maximal principal strains were lower than 6,130 microstrain when bone formation reaches zone 3.5 (70%) or more in models with osteotomy gaps of 5, 10, and 15 mm.

CONCLUSIONS

This indicates that plate removal without correction loss after MOWHTO may be possible when bone formation reaches zone 3.5 (> 70%) or more during 5- and 10-mm osteotomy gap corrections, and zone 4 (> 80%) or more during 15-mm gap correction. The present study results suggest that it would be safer to perform plate removal after obtaining sufficient bone formation rather than performing it near the osteotomy gap center (50%) to avoid correction loss considering both coronal and sagittal plane aspects.

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.

Patients aged 55 or older undergoing around the knee osteotomy have a higher rate of deep vein thrombosis but not overall early post-operative complications

Purpose

Osteotomies around the knee have been established as an effective method for treating varus or valgus malalignment associated with other knee pathologies in young and middle-aged patients. There is limited literature regarding the risks and complications based on patient age. The purpose of this study is to determine whether age influences as a risk factor for developing intraoperative and early post-operative complications in patients undergoing osteotomies around the knee.

Methods

A consecutive series of patients over 18 years old who underwent distal femoral osteotomy (DFO) or high tibial osteotomy (HTO) with a minimum follow-up period of 90 days were included. Demographic characteristics, surgical technique, intraoperative and post-operative complications up to 90 days were identified. A statistical comparison based on age younger than 55 years or 55 years and older was conducted to determine if patient age acted as a risk factor in the development of complications.

Results

A total of 159 osteotomies were included, of which 129 were HTOs. The average age was 46.16 years, and 118 patients were younger than 55 years. Seven hinge fractures were identified as the only intraoperative complication, while the overall early post-operative complication rate was 11.32%. The most frequent was deep venous thrombosis (DVT) in 5.66% of cases, followed by deep infection with a total rate of 2.52%. When performing the subgroup analysis by age, we observed a significantly higher rate of DVT in the group aged 55 years and older (p 0.036) (odds ratio 3.96 95% confidence interval 1.009-15.533; p 0.048); however, no significant differences were observed in the overall complication rate according to the age group of the patients.

Conclusions

This study reveals that in patients undergoing osteotomies around the knee, the most common post-operative complication was DVT. The rate of DVT was significantly higher in patients aged 55 years and older, although no differences were observed in the overall complication rate according to the patients' age range.

Level of evidence

Level III (retrospective cohort study).

Factors to improve odds of success following medial opening-wedge high tibial osteotomy: a machine learning analysis

BACKGROUND

Although high tibial osteotomy (HTO) is an established treatment option for medial compartment osteoarthritis, predictive factors for HTO treatment success remain unclear. This study aimed to identify informative variables associated with HTO treatment success and to develop and internally validate machine learning algorithms to predict which patients will achieve HTO treatment success for medial compartmental osteoarthritis.

METHODS

This study retrospectively reviewed patients who underwent medial opening-wedge HTO (MOWHTO) at our center between March 2010 and December 2015. The primary outcomes were a lack of conversion to total knee arthroplasty (TKA) and achievement of a minimal clinically important difference of improvement in the Knee Injury and Osteoarthritis Outcome Score (KOOS) at a minimum of five years postoperatively. Recursive feature selection was used to identify the combination of variables from an initial pool of 25 features that optimized model performance. Five machine learning algorithms (XGBoost, multilayer perception, support vector machine, elastic-net penalized logistic regression, and random forest) were trained using five-fold cross-validation three times and applied to an independent test set of patients. The performance of the model was evaluated by the area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 231 patients were included, and 200 patients (86.6%) achieved treatment success at the mean of 9 years of follow-up. A combination of seven variables optimized algorithm performance, and the following specific cutoffs increased the likelihood of MOWHTO treatment success: body mass index (BMI) ≤ 26.8 kg/m2, preoperative KOOS for pain ≤ 46.0, preoperative KOOS for quality of life ≤ 33.0, preoperative International Knee Documentation Committee score ≤ 42.0, preoperative Short-Form 36 questionnaire (SF-36) score > 42.25, three-month postoperative hip-knee-ankle angle > 1.0°, and three-month postoperative medial proximal tibial angle (MPTA) > 91.5° and ≤ 94.7°. The random forest model demonstrated the best performance (F1 score: 0.93; AUC: 0.81) and was transformed into an online application as an educational tool to demonstrate the capabilities of machine learning.

CONCLUSIONS

The random forest machine learning algorithm best predicted MOWHTO treatment success. Patients with a lower BMI, poor clinical status, slight valgus overcorrection, and postoperative MPTA < 94.7 more frequently achieved a greater likelihood of treatment success.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.