Abstract
Introduction and Aims: External tibial torsion associated with an increased ‘Q’ angle is an important factor in recurrent patella instability. It is surgically correctable with a rotational osteotomy of the proximal tibia above the patella tendon insertion. This technique ‘normalises’ the extensor mechanics and produces better results than patella tendon transfer.
Method: Fifty-five patients were assessed with a minimum of five-year follow-up. Patients in this study underwent initial conservative treatment consisting of l2 months of physio. Those patients who continued to have recurrent instability underwent surgery. Only patients without rotational abnormalities of the femur were included. Tibial rotation was assessed geriometrically, with the degree of external rotational corrected to 20–23 degrees. 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.
Results: Ninety percent of the patients were female with an average of 30 (range 14–45). Prior unsuccessful surgical procedures included lateral release (l6) Maquet procedure (l0), Hauser procedure (l6) medialisation of patella tendon (l0), semitendinosis tenodesis and patellectomy (two). Post-operative follow-up average five to 8.2 years. Pre-operative external tibial torsion averaged 45 degrees (range 40–65 degrees) with an average rotational correction of 25 degrees. The average pre-op ‘Q’ angle was 27 degrees and post-op 14 degrees. Average pre-op functional score has 40 and post-op 70 degrees. Outcome assessment of the 55 knees showed 26 excellent, 16 good and 13 poor. Overall 76% of the knee were good – excellent. Of the 16 patients with associated anterior knee pain, 13 obtained good-excellent results. Patients with less painful symptoms pre-op, had significantly better outcomes. Knees that had undergone multiple unsuccessful surgical procedures, had significantly poorer outcomes. Uniplanar patella tendon transfer in these cases generally results in continued anterior knee pain.
Conclusions: Derotational osteotomy re-aligned the extensor mechanism in cases of recurrent dislocation of the patella secondary to external tibial torsion. All patients had some improvement with the surgery, but the patients with poor outcomes continued to have anterior knee pain.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
At least one of the authors is receiving or has received material benefits or support from a commercial source.
