Poster 283: Revision Patellofemoral Surgery: A Retrospective Cohort Analysis

Abstract

Objectives: To report demographic and radiologic data, and clinical outcomes of patients undergoing revision surgery for patellar instability Methods: This is a retrospective cohort study. We included patients undergoing revision surgery for patellar instability between January 2010 and January 2022 in our institution. Exclusion criteria included patients with missing information regarding their primary surgery, patients with congenital disorders and patients with a history of distal femoral or proximal tibial osteotomy. Statistical analysis was performed using SPSS v. 20. Results: Ninety-six patients underwent revision surgery for patellofemoral instability. Eight patients were excluded based on exclusion criteria (Figure 1). Of the 88 patients included in final analysis, 44 (50%) had their primary surgery in our institution and revision rate in our institution was 3.8%. Primary surgeries included lateral retinacular release (LRR):18, medial patellofemoral ligament (MPFL) reefing: 19, MPFL reconstruction (MPFLR): 33, Tibial tubercle osteotomy (TTO): 24 (Table 1). Revision surgeries included: Lateral patellofemoral ligament reconstruction for iatrogenic medial instability: 6, MPFL release for persistent pain: 3, MPFLR: 36, MPFLR with Patellar tendon shortening: 5, MPFLR with Trochleoplasty: 4, Revision of femoral screw: 1, TTO: 19, TTO+MPFLR: 10, TTO+Trochleoplasty: 1, TTO+MPFLR+Trochleoplasty: 3 (Table 2). Patients having LRR as primary surgery had more female patients and higher patellar tilt, MPFLR patients had higher incidence of trochlear dysplasia, MPFL reefing patients were younger (Table 1). In our cohort of patients undergoing revision surgery for patellar instability, the mean tibial tubercle-trochlear groove (TT-TG) distance was 17.2 mm and the mean Caton-Deschamps Index (CDI) was 1.42. The incidences of trochlear dysplasia and skeletally immature patients were 61% and 68.2%, respectively (Table 1). The Median follow up period after revision surgery was 81 months. The overall complication rate after revision surgery was 12.5% (11/88) and occurred at a median of 31.5 months. Ten patients had recurrent patellar instability and one patient had tibial tubercle fracture (Table 3). Conclusions: The overall incidence of revision surgery was 3.8 after a primary surgery for patellar instability at a median of 31.5 months. Complications occur in 12.5% of patients after the revision surgery with the majority (10/11) being recurrent patellar instability. In our cohort, CDI and the incidences of trochlear dysplasia and skeletally immature patients were increased while the mean TT-TG distance was not.