Dislocation of the kneecap
Dislocation of the kneecap is a common problem in small and medium-sized dogs. It occurs in both young and older animals. It should be noted that the later the problem is diagnosed, the longer the treatment and rehabilitation takes.
Dislocation of the patella is caused by a complex of factors. There is virtually never a single cause of patellar luxation. There are always at least two of the following causes: shallow patellar groove, varus/valgus deformity of the femur or tibia, deviation of the tibial tuberosity.
Degrees of cervical dislocation:
Depending on the bony changes and the position of the kneecap when the knee joint is flexed, the severity of the dislocation varies and is divided into grades.
Grade I – The patella does not dislocate on its own and the joint movement is normal. The patella can be dislocated by pushing it out of the joint, but only when the leg is extended and the patella returns to its anatomical position immediately after the joint is released. This degree of dislocation does not cause any clinical symptoms.
Grade II – The patella dislocates spontaneously but returns spontaneously. Rarely causes episodes of claudication, but damage to the articular surface occurs.
Grade III – Nipple permanently dislocated. It can be restored to its anatomical position when the leg is extended, but it disappears immediately when the leg is relaxed. Causes frequent episodes of claudication and arthritis of the knee joint.
Grade IV – The neck is permanently dislocated and cannot be restored to its anatomical position. The joint has a reduced range of motion (does not fully extend or flex). Limping is constant, signs of arthritis are prominent and all parts of the joint are affected over time.
Treatment
In the case of a first degree dislocation, no treatment is required. For all other degrees of dislocation, especially if claudication is present, treatment is required. Dislocation of the patella is treated only surgically, combining several of the following techniques:
- Deepening of the “kneecap groove”
- Rotation of the tibial tuberosity
- “Tightening” the joint capsule
- Correction of bone deformities
- Replacement of the patellar groove with an artificial one
The essence of the treatment is to straighten and redirect the mechanical axis of the knee joint so that it passes through the patellar groove.