ROTATIONAL HIGH TIBIAL OSTEOTOMY FOR PATELLA INSTABILITY.

Abstract

Fifty-five patients were assessed with a minimum of five- year follow up. Patients in this study underwent initial conservative treatment consisting of twelve months of physio. Those patients who continued to have recurrent instability underwent surgery. Only patients without rotational abnormalities of the femur were included. Tibial rotational was assessed geriometrically, with the degree of external rotation corrected to 20 – 23°. Those patients with associated patella alta underwent a distal transfer of the patella tendon also. Assessment included range of motion, thigh girth, quads strength, effusion and a modified Lystrom knee score assessed function and pre and post-op radiographic assessment.

The purpose of this paper is to report on the results of rotational osteotomy of the proximal tibia to treat patella instability.

At a mean follow-up of seven years (range 5 – 8.2) 76% of knees treated for congenital dislocation of the patella with external tibial torsion, achieved good to excellent results.

External tibial torsion associated with an increased “Q” angle is an important factor in recurrent dislocation of the patella. It is surgically correctable with a rotational osteotomy of the proximal tibia above the patella tendon insertion. This technique “normalizes” the extensor mechanics and produces better results than patella tendon transfer.

Ninety percent of the patients were female with an average age of thirty (range fourteen to forty-five years). Prior unsuccessful surgical procedures included lateral release (sixteen) Maquet procedure (ten) Hauser (sixteen) medialization of the patella tendon (ten) semitendinosis tenodesis and patellectomy (two). Pre-operative external tibial torsion averaged 45° (range 40° – 65°) with an average rotational correction of 25°. The average pre-op “Q” angle was 27° and post-op 14°. Outcome assessment of the fifty-five knees showed twenty-six excellent, sixteen good and thirteen poor. Overall 76% were good to excellent.

Outcome assessment was performed using a modified Lysholm score and the Tegner activity scale. The average pre-op score was forty and post-op seventy. Patients with less painful symptoms pre-op had significantly better outcomes. Knees that had undergone multiple unsuccessful surgical procedures had poorer outcomes.