Abstract
Introduction
Habitual dislocation of the patella is rare in children. Several procedures have been described to stabilise the patella by lateral release and medial check-reins. The results are unpredictable. The failure is probably due to passive stretching of the static stabilisers of the patella ie. tendons and capsule. The aim of this paper is to describe the outcome of Pes Anserinus transfer for habitual dislocation of the patella in children.
Methods
Eleven children (13 knees) were reviewed retrospectively between 1990 and 2008 following surgical realignment. The age ranged between 5-13 years. Two had ligamentous laxity. Nine dislocated in flexion and 2 in extension. Through a lateral incision the iliotibial band, vastus lateralis and lateral capsule were released. Through a medial incision the capsule was reefed and the pes anserinus insertion was transferred to the medial side of the patella and its tendon. The vastus lateralis was reattached more proximally to the rectus. Quadriceps rehabilitation was started 4 weeks following plaster immobilisation.
Results
The wounds healed well. Scar thickening was seen in 2 children. Extensor lag of 20°-30° improved by 4-6 months. Squatting was possible in all at 1-8 year follow-up. One recurrence occurred following a fall. The results were graded satisfactory in 12 knees and poor in 1.
Conclusion
Static stabilisers have been shown to stretch when used as check reins in habitual dislocations of the patella. The pes anserinus transposition is a broad base anchorage providing dynamic stability. It acts as a physiological, non-stretchable sling as its neurovascular supply is intact compared to severed tendon or capsules used as medial check reins.
