Clinical results of surgical correction of medial luxation of the patella in dogs.

Thirty-four dogs that had surgical correction of medial patellar luxation (MPL) in 52 stifle joints were examined after a minimum follow-up period of 1 year (median, 3.6 years). The dogs were divided into the following three groups depending on their age at the time of surgery: group 1, 3 to 6 months; group 2, 8 to 20 months; and group 3, 2.2 to 12 years. Two of the dogs in group 3 had ruptured their cranial cruciate ligament in addition to having MPL. The results were based on a clinical assessment of the animal's gait, and physical and radiographic examination of the stifle joints. Six of seven stifle joints evaluated in group 1 had radiographic evidence of moderate to severe degenerative joint disease of the patellofemoral joint, and in two of the joints recurrence of MPL was observed. Failure to maintain reduction of the patellofemoral joint was also observed in 11 of 22 (50%) and 12 of 23 (52%) of the stifle joints in groups 2 and 3, respectively. In the latter groups, mild degenerative joint disease was evident radiographically in stifle joint that had not maintained reduction. Four of the 34 dogs were consistently (n = 2) or intermittently (n = 2) lame; the two dogs that were consistently lame had cranial instability of the stifle consistent with rupture of the cranial cruciate ligament. In the latter two dogs, the cranial cruciate ligament had been intact at the time of surgery for correction of MPL.