To compare the clinical outcomes of intra-capsular vs. extra-capsular lateral retinacular release in the treatment of excessive lateral pressure syndrome of patella using two novel surgical techniques: A retrospective comparative study.

Abstract

Purpose: To retrospectively compare the clinical outcomes of intra-capsular vs. extra-capsular release of the lateral patellar retinaculum using 2 novel surgical techniques: the capsule-uncut immaculate lateral retinacular release (CUI method), and the L-shaped lateral retinacular release (L-shaped release).

Methods: This is a retrospective comparative study. The clinical data of patients admitted to our department between October 2010 and October 2020 were retrospectively analyzed. Patients diagnosed with excessive lateral pressure syndrome and treated with arthroscopic retinacular release, with complete imaging data, and followed up for >1 year were included in the study. Previous history of knee surgery, cruciate ligament or collateral ligament ruptures, neoplastic diseases of the knee, patellar instability, history of knee fracture, varus/valgus of the knee joint, or Q angle >20° were exclusion criteria. All the included cases were divided into 2 groups based on the surgical method and subsequently stratified by age. The visual analogue pain scale was used to evaluate the degree of knee pain. Lysholm score and the International Knee Documentation Committee knee evaluation form score were used to evaluate knee function and activity. The preoperative and postoperative patellar tilt angles of the affected knee were measured. Comparison between groups was performed by the Wilcoxon test or the Mann-Whitney U test. Count data was represented by frequency, and comparison between groups was performed by χ² test. Mann-Whitney U test and multiple linear regression model were used for univariate and multivariate analysis.

Results: The clinical data of 200 patients were retrospectively analyzed. After screening by inclusion and exclusion criteria, 90 cases met the inclusion and exclusion criteria and were included in this study. The postoperative visual analogue scale scores of both groups were significantly lower than those before operation (p<0.001), and the postoperative Lysholm score and the score of the postoperative International Knee Documentation Committee knee evaluation form of the 2 groups were significantly higher than those before operation (p<0.001). The L-shaped release group was significantly higher than the CUI method group in Lysholm score (p=0.008). In the age ≥50 years group, the Lysholm score of the CUI method group was significantly lower than the L-shaped release group (p<0.001), and the changes in patellar tilt angle were significantly larger in the CUI method group than in the L-shaped release group (p=0.016). In the age <50 years group, there was no significant difference.

Conclusions: Both the surgical methods have good clinical effects. L-shaped release is superior to the CUI method in improving knee function in the elderly patients (≥50 years old), while the CUI method is superior to L-shaped release in correcting patellar tilt in the elderly patients. In young patients, the CUI method has the same clinical effect as L-shaped release. The L-shaped release is relatively simple with a short learning curve, making it suitable for beginners treating younger patients with mild lateral contracture. However, the CUI method is more recommended for patients with severe lateral patellar tilt, obvious lateral contracture thickening, and elderly patients.