Vet360 Vol 4 Issue 3 June 2017 Vet360 - Page 13

SURGERY Grade Description Grade 1 Patella can be luxated but spontaneous luxation seldom occurs. Once the patella has been luxated during clin- ical exam, the patella spontaneously reduces when the examiner releases pressure. The patella is stable in the trochlear in full range of motion Grade 2 Angular and rotation deformities of the femur may be present. The patella can be luxated and remains luxated through full range of motion unless reduced by the examiner. The animal can clinically reduce the patella and this is seen with the skipping gait. Once reduced the patella remains in the trochlear groove for the full range of stifle motion Grade 3 Angular and rotational deformities are often present. The patella remains luxated most of the time. The patella can be reduced by the examiner however normal range of motion of the stifle lead to luxation of the patella Grade 4 Moderate to severe angular limb deformities are often present. The patella is permanently luxated and cannot be reduced to the trochlear groove at any point in the normal range of motion of the stifle. The trochlear groove itself is often shallow or convex Table 1. Grading Patella luxation in the dog condyle. Other studies have shown an increased angle of inclination of the femoral neck is associated with patella luxation in small breed dogs. Large breed dogs seem to have a relatively normal conformation of the femur when compared with small breed dogs. However large breed dogs with MPL tend to have a relative degree of patella alta (high-riding patella - structurally found more proximal in the trochlear groove) when compared to the confor- mation of normal large breed dogs, this may be cause or consequence of MPL in large breed dogs. SURGICAL REPAIR Surgical repair of patella luxation should be performed on animals showing clinical signs of lameness associated with the patella luxation or in young animals to prevent the long-term complications later on in life from the patella Figure 2A luxation. The main goal of surgical repair is re-alignment of the patella-quadriceps mechanism leading to normal sliding of the patella in the patella groove. Surgical repair has two categories, a release or an augmentation of the soft tissue components and corrective distal femoral os- teotomy (CDFO) or tibial crest transplant (TCT). It has been shown that soft tissue procedures performed without correction of the bone deformities have a high failure rate and should never be used as a sole method of repair. Surgical complications using the current tech- niques are reported as high as 85-48%. Surgical compli- cations using the TCT in combination with soft tissue re- pair techniques are reported to be as high as 20%. These complication rates should be considered to high for a condition that is relatively common. (Fig 2a, 2b) Figure 2B Issue 03 | JUNE 2017 | 13