Factors Associated With Unfavorable Radiological Outcomes After Opening-Wedge High Tibial Osteotomy for Varus Knees

Impact of lower limb alignment abnormality (physiologic knee valgus) on the functional recovery outcome of athletes with meniscal injuries

OBJECTIVE

This study aimed to investigate the impact of lower limb alignment abnormalities, specifically physiological knee valgus, on the functional recovery outcomes of athletes with meniscal injuries. It also examined the factors influencing these abnormalities to provide scientific evidence for treatment and rehabilitation of related sports injuries.

METHODS

We conducted a retrospective study of 118 athletes from Guizhou Normal University, who were divided into two groups based on the presence or absence of lower limb alignment abnormalities. The Simple group comprised athletes with isolated meniscal injuries, while the Combined group included athletes with meniscal injuries and concurrent lower limb alignment abnormalities. We assessed the functional status of both groups and analyzed factors influencing lower limb alignment abnormalities.

RESULTS

Of the 118 athletes, 46 (38.98%) exhibited lower limb alignment abnormalities, and 72 (61.02%) did not. No significant differences in general characteristics were found between the groups (all P > 0.05). The Combined group displayed higher Visual Analog Scale (VAS) scores and Functional Performance Test (FPT) results (coordinated contraction, shuttle run, CarioCa) compared to the Simple group (P < 0.05). Conversely, joint range of motion (ROM), knee muscle strength (flexors), and International Knee Documentation Committee (IKDC) scores were lower in the Combined group (all P < 0.05). Multivariate logistic regression analysis identified active ROM < 105.32°, passive ROM < 101.66°, and knee muscle strength (flexors) < 84.41 N as risk factors for lower limb alignment abnormalities (P < 0.05), while FPT acted as a protective factor (P < 0.05). The combined testing model demonstrated higher predictive efficacy (AUC = 0.903, 95% CI: 0.852-0.955, P < 0.001).

CONCLUSION

Lower limb alignment abnormalities significantly affect the functional recovery outcomes of athletes with meniscal injuries. Factors such as ROM, knee muscle strength, and IKDC score may pose risks for these abnormalities, whereas FPT can provide protective benefits. Timely detection and correction of lower limb alignment abnormalities during the rehabilitation process from meniscal injuries are crucial to enhance recovery and improve prognosis.

Development of a machine learning model for identifying the optimal situation favoring double-level osteotomy over single-level high tibial osteotomy

BACKGROUND

This study aimed to develop a machine learning (ML) model to identify the optimal situation wherein double-level osteotomy (DLO) is favored for severe varus knees by analyzing unfavorable outcomes. This study hypothesized that there are the most favorable algorithms and contributing factors for identifying the optimal situation favoring DLO over opening-wedge high tibial osteotomy (OWHTO).

METHODS

Data were retrospectively collected from patients who underwent OWHTO (505 knees). Unfavorable outcome parameters were defined as follows: (1) medial proximal tibial angle (MPTA) > 95°, (2) joint line convergence angle (JLCA) > 4° (insufficient medial release), (3) JLCA < 0° (medial instability), (4) recurrence of varus deformity, and (5) lateral hinge fracture. The input data for the ML model included demographic data and preoperative radiological and intra-operative factors. The ML model was used to evaluate overall and to evaluate each unfavorable outcome. Interpretation by the model was performed by SHapley Additive exPlanations.

RESULTS

The unfavorable group had a larger JLCA and MPTA preoperatively than the favorable group in the conventional comparison. The light gradient boosting machine (LGBM) demonstrated the highest AUC of 0.66 and F-1 score of 0.72 among the ML algorithms. In the overall assessment, the preoperative weight-bearing line ratio (WBLR) was the factor that contributed the most, followed by the preoperative JLCA and the ΔWBLR. ΔWBLR and the preoperative JLCA were the contributing factors for each outcome.

CONCLUSIONS

The LGBM model was superior in predicting the optimal situations favoring DLO over OWHTO. Preoperative WBLR, preoperative JLCA, and ΔWBLR significantly contributed to the unfavorable outcomes overall and for each outcome in the ML model.

Postoperative change in the joint-line convergence angle is associated with inaccurate correction in open-wedge high tibial osteotomy

OBJECTIVE

Accurate correction is a prerequisite for the favorable outcomes of open-wedge high tibial osteotomy (OWHTO). However, previous studies have reported disappointing results regarding correction accuracy despite the use of intra-operative navigation, which implies that a certain factor other than bony components is involved in the inaccurate correction (mainly overcorrection). The joint-line convergence angle (JLCA) can represent soft tissue effects in OWHTO. This study tried to determine whether the postoperative change in the JLCA (∆JLCA) led to inaccurate correction.

METHODS

Medical records of 78 OWHTO patients from 2005 to 2021 were retrospectively reviewed. The hip-knee-ankle angle (HKA) was measured with a positive value indicating varus alignment. Inaccurate correction was defined as postoperative HKA < - 3°. The JLCA was measured before and 6 months after surgery on long-standing hip-to-ankle radiographs, and ∆JLCA was defined as the difference between the preoperative and 6-month postoperative JLCAs. ∆JLCA was compared between the accurate correction group and the inaccurate correction group, and a receiver operating characteristic (ROC) curve was used to obtain the cutoff ∆JLCA at which the sensitivity and the specificity for inaccurate correction were maximized. Clinical outcomes were also compared between the groups using the knee injury and osteoarthritis outcome score (KOOS) at final follow-up (60.9 ± 53.3 months postoperatively).

RESULTS

Of the 78 patients, inaccurate correction was noted in 10 patients. The overall preoperative and postoperative HKAs were 7.0 ± 3.1° and - 0.4 ± 1.5°, respectively. The accurate correction group and the inaccurate correction group had a difference in ∆JLCA (p = 0.010). However, no significant difference was found in the preoperative HKA (p = 0.529). An ROC curve showed that the cutoff ∆JLCA was 1.9°. In the patients having ∆JLCA ≥ 1.9°, the mean JLCA was 4.9 ± 1.6° preoperatively and 1.7 ± 1.2° postoperatively. In the other patients having ∆JLCA < 1.9°, the mean preoperative and postoperative JLCA were 2.5 ± 1.8° and 2.3 ± 1.8°, respectively. The difference in the preoperative JLCA was significant (p < 0.001). The postoperative KOOS subscales did not differ according to correction accuracy.

CONCLUSION

Inaccurate correction in OWHTO, specifically valgus overcorrection, is associated with large ∆JLCA which represents the postoperative change of soft tissue effects. Overcorrection should be checked in cases of large preoperative JLCAs.