Articular cartilage damage is frequently noted at the time of medial patellofemoral ligament reconstruction and is associated with age and patellofemoral anatomy

Abstract

Introduction

Recurrent patellar instability is often managed with medial patellofemoral ligament (MPFL) reconstruction. Recent work has demonstrated poorer outcomes of MPFL reconstruction in patients with articular cartilage damage. We quantified prevalence and location of articular cartilage injuries in patients treated for patellar instability with MPFL reconstruction and identified factors associated with cartilage damage.

Methods

One hundred ninety-nine patients undergoing isolated MPFL reconstruction at 6 centers on 5 continents between 2016 and 2020 were prospectively enrolled. All procedures were performed for recurrent patellar instability. All patients underwent a diagnostic arthroscopy. Patellofemoral articular cartilage damage location and severity were recorded according to the International Cartilage Restoration Society (ICRS) system, with damage of ICRS grade 2 or greater defined as substantial cartilage damage. Patient and injury factors were compared based on the presence or absence of substantial cartilage damage. Multiple logistic regression models were created to identify factors associated with cartilage damage.

Results

One hundred eleven patients (56 ​%) were noted to have substantial patellofemoral articular cartilage injury (72 grade 2, 27 grade 3, 12 grade 4). Most patients (106) had patellar cartilage damage, with trochlear damage less common (19). Sixty-nine of the 106 patients (65 ​%) with patellar cartilage damage had medial patellar damage. The cartilage damage group demonstrated significantly increased age at surgery (p ​= ​0.022) and trends toward higher body mass index (BMI) (p ​= ​0.059), and lower Beighton score (0.059). Increased age at surgery (odds ratio ​= ​1.079, p ​= ​0.010) was the only significant predictor of substantial cartilage injury. Increased age at surgery, increased BMI, and increased tibial tubercle-trochlear groove (TT-TG) distance were associated with distal and lateral patellar chondral damage, while presence of knee hyperextension greater than 10° was associated with a decreased risk of medial chondral damage.

Conclusion

Substantial cartilage damage was present in 56 ​% of patients who underwent isolated MPFL reconstruction for recurrent patellar instability, with medial patellar lesions being the most common. Increased age at surgery was associated with increased risk of substantial patellofemoral cartilage damage. Increased age at surgery, increased BMI, and increased TT-TG distance were associated with distal and lateral patellar chondral damage.

Level of evidence

Level 3—case control study.