The hip, also known as the coxofemoral joint, consists of a ball and socket made up of the femoral head and the acetabulum of the pelvis. The joint is stabilized by the ligament of the head of the femur (which attaches inside the acetabulum), the joint capsule, and the surrounding musculature.
Hip luxation, or dislocation, refers to displacement of the femoral head (ball) from its socket via disruption of the surrounding stabilizers. Luxation is typically caused by an acute traumatic event. The amount of force needed (hit by car versus slip and fall) can vary depending on the individual dog and any possible predispositions. The most common predisposition in dogs is Hip Dysplasia.
Clinical signs
Sometimes the trauma is not witnessed. However, your pet will often have significant lameness in their hindlimb, typically not bearing weight. Your pet may hold the leg in a slightly lifted position and rotate the leg outward. If the dislocation is more chronic in nature, the lameness is often subtle.
Diagnosis
Orthopedic examination may reveal discomfort on manipulation of the hip joint along with crepitus, or grinding, on range of motion. Additionally, palpable femoral and pelvic landmarks may be noted to be abnormally positioned relative to each other.
However, the final diagnosis will be confirmed by radiographs (X-ray) to examine the direction of the luxation and if any concurrent fractures are evident. If your dog has sustained massive injury (often in hit by car situations), other more pressing issues will be addressed prior to the luxated hip.
Treatment
The goal of treatment is to restore function to the joint. If a luxated hip is not addressed, a false joint may form, but it will result in permanent lameness and potentially chronic pain. Restoring function can be achieved in a wide variety of ways. However, there are 3 main categories. The specific technique will depend on the nature of your pet’s and discussion between you and your pet’s surgeon.
Closed Reduction
In simple cases of hip luxation without any evidence of the fracture or pre-existing arthritis/dysplasia, the hip can sometimes be returned to its socket via closed reduction, typically within the first 3 days after injury. Closed reduction requires heavy sedation or anesthesia and manual traction techniques. After reduction, a bandage or hobbles may be applied to decrease the rate of reluxation. Unfortunately, approximately 50% of closed reduction cases will luxate again.
Open Reduction
If closed reduction is not physically feasible or reluxation occurs, open surgical reduction can be performed. Open reduction is typically augmented via joint capsule repair, joint capsule augmentation, or replacement of the ligament of the head of the femur (LHF). At MVUCS, we often replace the LHF in a procedure known as a ‘Toggle Rod’ along with repair of the joint capsule. A ‘Toggle Rod’ involves placement of a prosthetic ligament through a bone tunnel in the femoral neck and head and crossing into a hole drilled with in the acetabulum (socket).
Salvage Procedures
If restoration of the joint to its normal alignment is not feasible or desirable, a salvage procedure may be performed. These options include:
- Total Hip Replacement where a metallic ball and socket prosthetics are attached to the femur and pelvis. It is an expensive procedure, but it may give many years of pain-free use of the hips. Although the intent is for the implants to be permanent, complications may include infection or loosening after a period of time.
- Femoral head ostectomy involves the removal of the ball part of the joint, thus removing the source of discomfort. Small dogs often form a very functional “false joint.” Large dogs often do not tolerate this procedure as well, and FHO is only selected if pre-existing arthritis is very severe, there is concurrent fracture, or if the expense of the other procedures is prohibitive.