Recovery
Postoperatively your pet should be confined for 4-8 weeks in a small area. Physical therapy should be performed daily to maintain the range of motion of the joint and accelerate return to function. Effective surgical correction results in an anatomically and functionally improved knee joint. The outcome following surgery depends on the individual case and severity of changes present prior to surgery. Surgical correction of patellar luxations generally results in a successful outcome. Most dogs return to full function with pain-free motion and normal activity.

Patellar Luxation
Patellar luxation is a common problem in dogs and is occasionally seen in cats. The patella (kneecap) is a small bone within the patellar tendon that glides in a groove located in the femur on the front of the stifle (knee) joint (Figure 1). With patellar luxation, the patella moves outside of this groove. Typically, the patella in small breed dogs moves medially, or to the inside surface of the knee (Figure 2), while the patellas of large breed dogs tend to move laterally or to the outside surface of the knee (Figure 3). In small or toy breed dogs with medial patella luxation, the condition is most often seen in both knees and produces a bowlegged deformity. In large breed dogs with lateral patella luxation, the opposite occurs creating a knockkneed appearance. The failure of the patella to tract normally in the femoral groove as the pet walks results in mechanical alterations of the muscles and bones of the hindlimb, progressive deterioration of the cartilage lining of the knee joint and arthritis. Patellar luxation is graded on a scale from I to IV, IV being the most severe and is scaled on whether the patella is intermittently or permanently displaced. The disease can progress from the less severe to more severe grades over time. The more severe forms are often accompanied by malformation of the femur and tibia, as well as varying amounts of arthritis.

Diagnosis

Diagnosis of patella luxation is performed using radiographic evaluation and physical manipulation of the stifle joint. Signs vary depending upon the severity and duration of the problem. Radiographs will identify bony deformities and joint alterations. Palpation of the patella through a range of motion will help the surgeon assess how the patella tracts with movement and whether it can be returned to its normal position manually. Affected dogs can have intermittent or consistent hind limb lameness with visible conformation defects. When the clinical assessment is complete, the proper course of treatment can be selected.

Surgical Repair
Surgical techniques to correct patellar luxation are directed at securing the patella in a normal

• Tibial Tuberosity Transposition

The patella attaches to the lower leg via its patellar tendon at a bony site called the tibial tuberosity. This site may be malpositioned on the inside with Medial Patella Luxation, or on the outside with Lateral Patella Luxation. The surgeon can move the tibial tuberosity into proper alignment and secure it in place with a pin or wire. This procedure realigns the joint, patella and tendon and helps prevent dislocation from reoccurring (Figure 4).

Early correction of severe deformities is indicated to ensure good, pain-free function.