Lateral Opening Distal Femoral Osteotomy with Concomitant MPFL Reconstruction is Efficacious in Addressing Patellar Instability

Purpose: To describe the clinical and radiographic outcomes of patients undergoing a lateral opening distal femur osteotomy (DFO) to address valgus alignment and restore patellar stability.

Methods: A retrospective review of patients who underwent lateral opening DFO for recurrent patellar instability in the setting of valgus leg alignment at a single academic institution between January 2016 to December 2021 was performed. Patients without a minimum 24-month postoperative follow-up were excluded. Rates of recurrent patellar instability, patient-reported outcomes, and complications were assessed. Pre- and post-operative radiographic anatomic lateral distal femoral angle (aLDFA) was evaluated to assess alignment correction.

Results: 20 lateral opening DFO cases were included from 15 patients [mean age 19.6 years, mean follow-up 42.4 months (range 24-63 months)]. 19 of 20 (95.0%) knees experienced no recurrent patellar dislocation. 13 of 20 (65.0%) knees underwent re-operation [hardware removal (n = 10); revision stabilization procedure (n = 1); lysis of adhesions and manipulation under anesthesia (LOA/MUA) (n = 1); nonunion revision with bone grafting (n = 1). mLDFA significantly changed from 86.3 degrees preoperatively to 91.4 degrees postoperatively (p < 0.001). Mean aLDFA changed significantly from 77.4 preoperatively to 84.4 degrees postoperatively (p < 0.001). The final Kujala score had a median value of 92 (IQR 85.5 - 98), Lysholm score was 90 (IQR 76 - 95), and Tegner score was 5 (IQR 4 - 7).

Conclusion: Lateral opening DFO is an efficacious procedure to address recurrent patellar instability in patients with valgus leg alignment. The present retrospective case series demonstrates good functional outcomes and low rates of recurrent instability and major complications after a lateral opening DFO, despite a large proportion of patients having undergone previous surgery. There were relatively high rates of reoperation and hardware irritation.

Level of evidence: Retrospective case series; Level of evidence, 4.