Midterm Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability in Ehlers-Danlos Syndrome.

Background: Patellar instability is frequently encountered in patients with Ehlers-Danlos syndrome (EDS). The clinical outcomes of isolated medial patellofemoral ligament reconstruction (MPFLR) for patellar instability in patients with EDS are unknown. Purpose: To evaluate midterm clinical outcomes of isolated MPFLR for patellar instability in patients with EDS and factors affecting these outcomes. Study Design: Case series; Level of evidence, 4. Methods: In a retrospective study, 31 patients (n = 47 knees) with EDS and patellar instability who underwent isolated MPFLR for recurrent patellar instability between 2008 and 2017 and had a minimum 2-year follow-up were identified. Preoperative radiographic images were measured for anatomic risk factors. Clinical outcomes-including postoperative complications-were evaluated. Factors associated with MPFLR failure were identified. Postoperative patient-reported outcomes (PROs)-including the pediatric version of the International Knee Documentation Committee, the Kujala score, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale, the Banff Patellofemoral Instability Instrument 2.0, and the Knee injury and Osteoarthritis Outcome Score-were collected, and factors affecting PRO scores were analyzed. Results: The mean age of the cohort was 14.9 ± 2 years. At a mean follow-up of 7.2 years, 18 of 47 (38.3%) knees required reoperations, of which 9 of 47 (19.1%) knees required revision stabilization for recurrent patellar instability. Also, 7 of 31 knees (22.6%) with autografts failed compared with 2 of 16 (12.5%) with allografts ( Conclusion: At the midterm follow-up, 38.3% of patients with EDS required further surgery after isolated MPFLR for patellar instability; half of these revisions (19.1%) were to address recurrent instability. Recurrent instability after isolated MPFLR was more likely in younger patients and those who could touch the palm to the floor with their knees extended. Postoperative PROs were inferior; nonetheless, patient satisfaction was high.