Clinical application of femoral derotation osteotomy combined with medial patellofemoral ligament reconstruction for patellar dislocation with excessive femoral internal torsion

Abstract Recurrent patellar dislocation (RPD) is multifactorial disease, and excessive femoral internal torsion has been considered as an important risk factor for recurrence of patellar dislocation and graft failure after surgery 1 . Satisfactory clinical outcomes depend on correcting of the pathologic abnormalities around the patellofemoral joint and torsional deformity of the lower extremity. At present, conventional isolated medial patellofemoral ligament (MPFL) reconstruction without addressing excessive femoral internal torsion may lead to MPFL graft failure 2,3 , because increased femoral internal torsion can significantly increase a persistently lateralizing force on the patella 4 . Considering these predisposing factors and to provide an optimal treatment for RPD with increased femoral internal torsion, we presented our surgical technique regarding the clinical application of MPFL reconstruction combined with supracondylar femoral derotation osteotomy, and make a brief introduction of its surgical techniques. A 21-year-old female was initially admitted to our hospital for complaining her patellofemoral joint due to the recurrence dislocation (＞2 times). The full-leg standing anteroposterior (AP) radiographs, lateral views, and axial images showed that the normal patellar height and morphology of trochlea, neutral alignment of the lower extremity, while the hip-knee-ankle scans of 3-d reconstructive axial images identified that the femoral anteversion angle was increased to 32.4°. The degree of tibial external was 18.6° and the tibial tuberosity-trochlear groove (TT-TG) distance was 18.6 mm, demonstrating the normal TT-TG distance and tibial external (Fig.1). After that, the patient treated by double-bundle anatomical MPFL reconstruction combined with supracondylar femoral derotation osteotomy procedure.