Derotational femoral osteotomy using a retrograde intramedullary nail with medial patellofemoral ligament reconstruction as a treatment for recurrent patellofemoral instability.

Abstract

Derotational distal femoral osteotomy (D-DFO) in combination with a medial patellofemoral ligament reconstruction (MPFL-R) has been proposed as a surgical technique to treat recurrent patellofemoral instability (PFI). There is limited evidence regarding osteotomy fixation with an intramedullary (IM) nail in the treatment of recurrent PFI. This study aimed to determine outcomes following D-DFO with an IM nail prosthesis combined with MPFL reconstruction in the treatment of recurrent PFI. A retrospective analysis was performed of all patients in our unit with recurrent PFI who were subsequently treated with D-DFO via an IM nail fixation and MPFL reconstruction from January 2019 to August 2025. Post-operative factors recorded included the primary outcome of re-dislocation and secondary outcomes of time to union, length of hospital stay and complications. A total of 21 knees in 20 patients were included. The mean pre-operative imaging results were: tibial tubercle - trochlear groove (TT-TG) distance; 15.8 mm (standard deviation [SD] 4.7 mm), femoral anteversion angle (FAA); 20.7° (SD 8.8°), Insall-Salvati Index (ISI) 1.5 (SD 0.2), Patellar Tilt 29.8° (SD 12.2°). There was a 0 % re-dislocation rate and a 14.3 % complication rate. Our study adds to the evidence base in the management of recurrent patella instability. We report good outcomes following combined MPFL-R and D-DFO utilising a retrograde femoral IM nail for osteotomy site fixation. Further studies are required to continue to evaluate its feasibility and outcomes.