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Abrasion trochleoplasty results in slower return of limb function in comparison with techniques which preserve articular cartilage (Boone and others 1983) such as trochlear wedge (Boone and others 1983, Slocum and Devine 1985, Slocum and Slocum 1993) or block recession (Johnson and others 2001). Complications associated with these techniques per se, appear extremely rare with only single cases of lateral trochlear ridge fracture following block recession (Chase and Farrell 2010) and trochlear wedge migration (TWM) (Remedios and others 1992) being reported. Remedios and others (1992) offered no information on TWM other than the trochlear wedge was removed. This short communication reports TWM in two dogs and offers a hypothesis for its development.
A 4.5-year-old, male neutered, labrador was referred to the author for surgical correction of grade 2/4 (Roush 1993) right medial patella luxation. Trochlear wedge recession, tibial tuberosity transposition and lateral fascial imbrication were performed. Six days postoperatively the dog became acutely non-weight bearing in the operated limb while descending stairs. After 48-hours there was some improvement in limb function, although moderate lameness remained. Examination eight days postoperatively revealed moderate right hind lameness. The right stifle was moderately effused, had normal patella tracking and exhibited femoro-patellar joint crepitus. A firm but mobile mass was palpable on either side of the patella ligament. Palpation of this mass and stifle manipulation elicited a pain response. The pertinent stifle radiographic feature was distal migration of the trochlear wedge which had rotated 90° to lie horizontally …