Summary

Medial patellofemoral ligament (MPFL) reconstruction using FiberTape and knotless SwiveLock anchors was both less invasive and effective, with a rate of return to pre-injury sports of 92.9%, while higher BMI, bilaterally, and patella alta resulted in lower KOOS sports activity scores in competitive athletes.

Abstract

Purpose

Medial patellofemoral ligament (MPFL) reconstruction usually involves hamstring autografts and is associated with donor-site morbidity. The use of polyester high-strength suture tape (FiberTape®, Arthrex) and knotless SwiveLock® anchors (Arthrex) in MPFL reconstruction is less invasive and significantly improves patients’ quality of life and post-operative knee outcome measures. The purpose of this study was to investigate the return to pre-injury sports (RTS) after MPFL reconstruction using this technique for patellar instability.

Patients and Methods: This was a retrospective analysis of the 94 knees of 65 patients (16 males and 49 females, mean age; 19.9±9.8 years) surgically treated for lateral patellar instability between 2016 and 2020. All patients underwent MPFL reconstruction using FiberTape with knotless SwiveLock anchors and had a minimum 2-year follow-up. Demographic data, pre-operative sports activity level, time from surgery to RTS, Knee Injury and Osteoarthritis Outcome Scale (KOOS) scores, recurrent apprehension and re-dislocations postoperatively were collected. Tibial tuberosity to trochlear groove (TT-TG) distance on CT, patellar height (Insall-Salvati ratio, ISR) and trochlear dysplasia (trochlear depth) on lateral plain X-ray were measured. Factors associated with KOOS subscale scores were investigated using liner regression analysis.

Results

There were no patients with patella re-dislocation, however, 3 knees showed a positive apprehension sign at final follow-up. At pre-operative activity level, 28 of 65 patients played sports at a competitive level, 20 patients at a recreational level, and 17 did not play at all. The rate of RTS at competitive level was 92.6% (26 of 28 patients), and the mean time from surgery to RTS was 6.0±2.8 (3-12) months. For those at the recreational level RTS was 100%, and 5.6±2.3 (2-11) months, respectively. At the competitive level, the liner regression analysis showed lower KOOS sports activities scores were significantly related to higher Body mass index (BMI) (B=-2.49, p=0.00), bilateral case (B=-11.06, p=0.01) and higher ISR (B=-40.8, p=0.00). There was no significant correlation between KOOS sports activities score and age, gender, TT-TG distance or TD.

Discussions: The MPFL reconstruction using FiberTape and SwiveLock anchors was safe and effective for ability to RTS. The overall rate of RTS was 92.9%. Higher BMI, bilateral cases and patella alta resulted in lower KOOS sports activities scores in competitive athletes.