Arthroscopic Lateral Retinacular Release in Adolescents with Medial Patellofemoral Ligament-centered Knee Pain

Background: The medial patellofemoral ligament (MPFL) has been implicated as a common pain generator in adolescents with anterior knee pain. The purpose of this study is to report the clinical outcomes of arthroscopic lateral retinacular release (ALRR) for refractory MPFL-centered pain and to identify risk factors for poor outcomes and surgical failures. Methods: A single-surgeon database was queried to identify all patients undergoing ALRR. Inclusion criteria included minimum 12-month follow-up and ALRR performed for MPFL pain rather than for generalized anterior knee pain or patellar instability. All patients had persistent MPFL-centered pain despite participating in a nonsurgical protocol before surgery. Primary outcomes included International Knee Documentation Committee (IKDC) subjective score and need for further surgery, typically tibial tubercle osteotomy (TTO). Results: Eighty-eight knees in 71 patients [66 female, 5 male; average age, 15.7 y (range, 8.4 to 20.2 y)] were included. Average follow-up was 59 months (range, 12 to 138 mo). Average preoperative IKDC score was 41.9 (range, 18.4 to 67.8), whereas average postoperative IKDC score was 77.8 (range, 11.5 to 98.9; P<0.01). Postoperative IKDC scores were worse in patients with a preoperative sulcus angle of <134 degrees than those with sulcus angle of ≥134 degrees (69.9±22.1 vs. 82.0±12.5, P=0.04). Lower preoperative IKDC score correlated negatively with improvement of IKDC score postoperatively (r=-0.40, P<0.05). Seventeen knees (19.3%) subsequently underwent TTO for persistent symptoms. Patients who ultimately required TTO were younger than patients who did not (14.8±1.5 vs. 15.9±2.1; P=0.04) and had lower mean preoperative Blackburne-Peel ratio (0.95±0.25 vs. 1.11±0.24; P=0.02). Conclusions: This study demonstrates that patients with refractory MPFL-centered knee pain had significant improvements in clinical outcomes after undergoing ALRR at mean 5 years' follow-up. Poor outcomes and surgical failures were associated with lower preoperative IKDC score, younger age, lower preoperative Blackburne-Peel ratio, and sulcus angle of <134 degrees. Outcomes were not recorded prospectively, but mean IKDC scores <60 months postoperatively were similar to those collected ≥60 months after surgery (80.4 vs. 78.3, P=0.15). Level of Evidence: Level IV.