Descriptive Epidemiology of a Surgical Patellofemoral Instability Population of 492 Patients

Background: Patellofemoral instability (PFI) occurs most commonly in pediatric and adolescent patients, with evolving indications for surgery and changes in surgical techniques over the past decade. Purpose: To characterize the demographic, clinical, and radiologic characteristics of a large cohort of patients undergoing PFI surgery and investigate longitudinal trends in techniques utilized over a 10-year period at a tertiary-care academic center. Study Design: Case series; Level of evidence, 4. Methods: Electronic medical records of patients younger than 25 years of age who underwent primary surgery for lateral PFI from 2008 to 2017 at a single center by 1 of 5 different sports medicine surgeons were retrospectively reviewed. Demographic, clinical, and radiographic parameters of instability were analyzed. Routine surgical techniques included medial retinacular plication/reefing/repair (MRP), medial patellofemoral ligament reconstruction (MPFLR), tibial tubercle osteotomy (TTO), or a combination thereof, with or without lateral retinacular release (LR) or lateral retinacular lengthening (LRL). Exclusion criteria, selected for potentially altering routine surgical indications or techniques, included fixed/syndromic PFI, a formally diagnosed collagen disorder, cases in which a chondral/osteochondral shear fragment underwent fixation or was >1 cm in diameter, and body mass index >30 kg/m2. Results: Of the 492 study patients (556 knees; 71% female; median age, 15.2 years; 38% open physes), 88% were athletes, with the most common sports participated in being soccer, basketball, dance, football, gymnastics, and baseball/softball. While 91% of the cohort had recurrent dislocations, the 9% with primary dislocations were more likely to have small osteochondral fractures/loose bodies ( P < .001). Female patients were younger ( P = .002), with greater patellar tilt ( P = .005) than male patients. Utilization of MPFLR and TTO increased significantly over the study period, while use of MRP+LR decreased. Conclusion: Most patients younger than 25 years of age who underwent PFI surgery were skeletally immature, female, and athletes and had recurrent dislocations. The