Outcome Following Surgical Correction of Grade 4 Medial Patellar Luxation in Dogs: 47 Stifles (2001-2012)

Grade 4/4 medial patellar luxation (MPL) is a complex disease of the canine stifle that often requires surgical realignment of the patella to resolve clinical lameness. Outcome following surgery remains poorly described. Medical records were retrospectively reviewed for surgical correction of grade 4 MPL. Signalment and exam findings, surgical procedures performed, complications, and clinical outcome were reported. Data was statistically analyzed for association with major complication occurrence and unacceptable function following surgery. Forty-seven stifles from 41 dogs were included. The surgical procedures most frequently utilized for patellar realignment were the combination of femoral trochleoplasty, tibial tuberosity transposition, and joint capsule modification. Median in-hospital veterinary examination was performed at 69 days (range 30-179 days) following surgery. Full function was reported for 42.6% of cases (n = 20). Acceptable function was reported for 40.4% of cases (n = 19). Unacceptable function was reported for 17% of cases (n = 8). The overall complication rate was 25.5% (n = 12), with revision surgery for major complications required in 12.8% of cases (n = 6). Corrective osteotomies were associated with major complications (P < 0.001). In general, pelvic limb function improves following surgical correction of grade 4 MPL; however, a return to full function should be considered guarded.