Does Ligamentous Laxity Protect Against Chondral and Osteochondral Injuries in Patients With Patellofemoral Instability?

Background: Many patients undergoing medial patellofemoral ligament (MPFL) reconstruction for patellofemoral instability have chondral or osteochondral injuries requiring treatment. Hypothesis: In patients undergoing MPFL reconstruction for patellofemoral instability, those with ligamentous laxity (LAX) would be less likely to have chondral or osteochondral defects requiring surgical intervention compared with those with no laxity (NLX). Study Design: Cohort study; Level of evidence, 2. Methods: Included were 171 patients with patellofemoral instability (32 men, 139 women; mean age, 22 years [range, 11-57 years]) who underwent MPFL reconstruction between 2005 and 2015. Patients with a Beighton-Horan score ≥5 were considered LAX (n = 96), while patients with scores <5 were considered NLX (n = 75). Preoperative magnetic resonance images were evaluated to determine the presence, size, and location of chondral or osteochondral injury as well as the grade according to the Outerbridge classification. Documented anatomic measurements included tibial tubercle-trochlear groove (TT-TG) distance, Caton-Deschamps Index (CDI) for patellar height, and the Dejour classification for trochlear dysplasia. Results: Of the 171 patients, 58 (34%) required a surgical intervention for a chondral or osteochondral defect: chondroplasty (29/58; 50%), particulated juvenile cartilage implantation (18/58; 31%), microfracture (16/58; 28%), osteochondral fracture fixation (2/58; 3.4%), and osteochondral allograft (2/58; 3.4%). While there was no statistical difference in the proportion of patellar chondral or osteochondral injuries between patients with NLX (58%) versus LAX (67%) (P = .271), there was a significantly higher rate of patellar grade 3 or 4 injuries in the NLX (74%) versus LAX (45%) group (P = .004). Similarly, there was no difference in femoral chondral or osteochondral injury rates between groups (P = .132); however, femoral grade 3 or 4 injuries were significantly higher in the NLX (67%) versus the LAX (13%) group (P = .050). After adjusting for age, sex, radiographic parameters (TT-TG distance and CDI), and trochlear morphology, patients with LAX were 75% less likely to have had a grade 3 or 4 patellar cartilage injury compared with patients with NLX (P = .006). Conclusion: For patients who sustained patellar or femoral chondral or osteochondral injuries, compared with their counterparts with NLX, patients with LAX were less likely to have severe (grade 3 or 4) injuries requiring surgical intervention.