Coxofemoral Hip Luxation in Cats

The hip can dislocate in various directions, the most common being craniodorsal (in the direction of both the head and the back). Hip luxations are the most common type of dislocation in cats. This issue is most often seen in cats who have suffered severe trauma, however, disease can also be the underlying issue. Any age or breed of cat can be susceptible to hip luxations. Treating a dislocated hip quickly can help reduce chronic, degenerative arthritis from developing in the cat.

The hip joint in a cat is made up of a ball and socket joint composed of the femoral head (top of the thigh bone) in the pelvic socket. The head of the femur is attached to the pelvic socket by the round ligament, and further secured by the adductors, abductors, and gluteals. When the round ligament ruptures or stretches out, the top of the femur can dislocate from the socket of the pelvis. This is commonly referred to as a coxofemoral hip luxation.

If your cat has experienced serious trauma, multiple injuries may be present. Some of these injuries may be life-threatening, so immediate veterinary attention is needed. Known symptoms of hip dislocation are as follows:

• Lameness
• Gait abnormality
• Pain
• Holding a leg up
• Limping
• One limb visibly shorter or longer than the others
• “Floppy” limb
• Cracking of the joint 

The most common cause of hip dislocation in a cat is from being hit by a car. While extreme physical trauma is usually to blame, degenerative diseases can also be at play. Known causes of hip luxation include:

• Trauma (most often by car accidents or slips and falls)
• Hip dysplasia
• Cancer of the coxofemoral joint, pelvis or femur

If your cat has suffered a major injury, rush it to a veterinary clinic or animal hospital immediately. Once there, a veterinarian will perform a physical examination to determine all injuries present. Life-threatening problems will be treated first. To diagnose hip luxation, an orthopedic evaluation will be conducted. You will be asked to provide your cat’s full medical history to determine the likelihood of disease. Full blood work will be needed, including a complete blood count and a biochemical analysis. This can help identify malignancy within the cat.

X-rays will be required of the pelvis and the chest to determine the extent of the damage and the direction of luxation. The cat will also be monitored for fractures at this point. Sedation is needed for best imaging results. A pinch test may be conducted to help determine if a luxation has occurred. This involves placing the thumb between the greater trochanter (a bump near the top of the femur) and the tuber ischii (swelling of the bone). Rotating the femur towards the tail of the cat should cause the thumb to be forced up by the greater trochanter if the joint is intact. If the thumb is not forced up, the hip has been dislocated. 

Depending on the severity of the trauma present and whether any fractures exist, both surgical and nonsurgical treatment options may be chosen. Cats who have experienced a hip luxation recently, or who are poor surgical candidates should explore the nonsurgical options first. Treating the ailment as soon as possible provides the best outcome for healing.

Closed Reduction 

This is the nonsurgical repair of a hip luxation. It should be performed within four to five days of the injury occurring to reduce permanent cartilage damage. The cat is put under general anesthesia while the hip is manually placed back in the joint. The limb is then kept in position with a sling which must stay on for a number of weeks. This procedure carries a 50 percent success rate. 

Open Reduction 

This treatment involves the surgical placement of the hip back into the socket. Often implants and supports are added to the joint to strengthen it. Possible procedures to place supports include surgical anchors, joint reconstruction, prosthetic joint capsule, greater trochanteric transposition, toggle rod fixation, and De Vita pin insertion. The De Vita pin is associated with many complications and may not be the safest choice for the cat. Discuss all possible options with your veterinary surgeon.

Femoral Head Ostectomy 

If the injury present is too severe for reduction procedures, an FHO may be required. This surgery involves removing the top of the femur and placing the new bone top into the pelvic socket to create a false joint. This surgery has good success with a mild loss of leg movement. The possibility of repeated luxation is removed with an FHO.

Total Hip Replacement 

The joint is reconstructed using synthetic materials to restore leg function to the cat. These implants help support the femur into the new pelvic socket.

The majority of cats recover well from hip luxation procedures. Approximately 50 percent of closed reduction patients, and up to 20 percent of open reduction patients will need additional repair surgeries. If your cat has been given a sling, you will need to monitor the sling closely to ensure it stays in place and that no sores develop from chafing. The leg needs to be kept in position for several weeks to heal correctly. All activity should be limited during this time, as an injury can cause loss of leg function once healed. 

If your cat has undergone surgery, follow all at-home care instructions closely. Monitor the incision site to ensure no infection develops. Activity should be restricted for up to 8 weeks post surgery. A follow up appointment with the veterinarian will require X-rays to show how the joint is healing. Your cat may need physiotherapy or other special exercises to help strengthen the limb after surgery. Supplements such as glucosamine or NSAIDs (non-steroidal anti-inflammatory drugs) should be given to the cat to help reduce the onset of arthritis in the joint. Most cats acquire normal leg function once the healing process is complete.