Exploring predictors of medial collateral ligament tears in lateral approach total knee replacement: A retrospective study

Background

Medial collateral ligament (MCL) tears are uncommon in total knee replacement (TKR), but they pose significant surgical challenges, affecting recovery and outcomes. This study analyzed 18 (1.3 %) MCL tear cases from 1429 TKR procedures using a lateral subvastus approach. Logistic regression with Lasso regularization was used to assess factors like gender, BMI, and knee alignment. Midsubstance disruptions were the most common. MCL tears were more frequent in females, those with higher BMI, and valgus alignment. The Lasso model achieved an AUC of 0.83 and an F1 score of 0.76.

Methods

A retrospective analysis on 1429 TKR cases performed by three experienced surgeons using the Optimotion Implant system and specialized MCL retractors was conducted. The lateral subvastus approach without parapatellar arthrotomy. A hinged knee brace was applied postoperatively and a posterior stabilized insert was used for MCL tears. Demographic data were collected, and a Lasso regression model with data balancing, was employed to identify MCL tear predictors.

Results

Among the 1429 TKR cases, 18 cases (1.3 %) involved MCL tears. The average age of these patients was 67.3 years (not statistically significant). The average BMI for patients with MCL tears was 36.7, significantly higher than the overall group average of 31.5, suggesting a link between higher BMI and MCL tears. Females were notably more affected, making up 88.9 % of the MCL tear cases compared to 11.1 % of males. Regarding knee alignment, 38.9 % had valgus alignment (p < 0.05), No significant differences were observed in knee flexion or Knee Society Scores (KSS) following MCL tears.

Conclusions

Gender, BMI, and knee alignment are significant factors influencing the incidence of MCL tears in TKR procedures. The Lasso model effectively identified individuals at higher risk. Preventive measures, including surgeon training and the use of specialized MCL retractors, were implemented. Functional outcomes such as knee flexion and KSS scores did not show significant differences post-MCL tear.