The hip is a simple ball and socket joint with a wide range of movement in all directions, and its efficient function is essential to normal hind-limb movement. The joint comprises the acetabulum, a cup-shaped depression in the pelvis (this forms the ’socket’), and the femoral head, which is part of the femur (thighbone). The femoral head forms the ’ball’ of the ’ball and socket’ joint. The stability of the hip joint comes from how well the femoral head and acetabulum fit together, the ligament of the head of the femur that attaches the femoral head to the deepest point of the acetabulum, a thick joint capsule, and the surrounding muscles.
What is meant by hip dislocation?
When the hip dislocates (also known as hip luxation), the femoral head is displaced from the acetabulum (out of the socket); in most cases, the femoral head will be positioned above and in front of the acetabulum. The most common cause of hip dislocation is blunt force trauma, such as a fall or an automobile injury, but any traumatic injury to the hip area may cause a hip dislocation.
Hip dysplasia, a common developmental disorder, can predispose a dog to hip dislocation. (See the handout “Hip Dysplasia in Dogs” for more information.)
What are the clinical signs of a dislocated hip?
Most dogs with a hip dislocation will have severe hind limb lameness and may not be able to put any weight on the affected limb. The affected limb is often carried in a flexed (folded or pulled up) position, rotated slightly outwards, and may appear shorter than the other limb. If the dislocation has been chronic, there may only be a subtle lameness, especially in small dogs, but the limb will still be carried abnormally and will have decreased muscle.
How is a hip dislocation diagnosed?
The hip joint will be painful when your veterinarian manipulates it during the physical examination of your dog. In addition to this, your veterinarian may feel a grinding sensation (crepitus) when the femur is moved. Because this condition is painful, your dog may not allow manipulation, and sedation may be required for a full examination.
"Most dogs with a hip dislocation will have severe hind limb lameness and may not be able to put any weight on the affected limb."
The diagnosis is confirmed by a radiograph (X-ray), which will show the direction of dislocation and whether any part of the hip joint is fractured. If a fracture is present, it may be more challenging to repair the dislocation. If your dog has other, more serious or life-threatening injuries, they will be treated before your veterinarian even considers addressing the dislocated hip.
What is the best treatment for a dislocated hip?
In most cases of hip dislocation, it is desirable to replace the femoral head in the acetabulum. The only time when it may be reasonable not to do this is if your dog has some other illness or if other factors make anesthesia too risky to undertake. A false joint may form if the hip is left dislocated, but the dog will have permanent lameness and potentially chronic pain.
In many cases, it is possible to replace the femoral head in the acetabulum by manipulation under general anesthesia (closed reduction). The success of a closed reduction increases if the dislocation is recent (less than 72 hours). After the dislocation is reduced or replaced, a supportive wrap or bandage may be applied to immobilize the leg and prevent the hip from reluxating (popping back out). This bandage or support wrap will remain in place for 4 to 14 days. Some dogs may not tolerate this bandage well. In this case, your dog must be closely supervised and his activity restricted. It is important that the bandage is not too tight and that your dog is not too distressed by the support wrap.
In some cases of hip dislocation, it will be impossible to replace the femoral head in the acetabulum, or it may keep slipping out of the socket. In these cases, surgery is indicated to repair the injury. The specific surgical repair technique will depend on the nature of the injury and the veterinary surgeon’s preference.
What post-operative care does my dog need?
If it has been possible to replace the femoral head into the acetabulum without surgery, your dog will most likely be prescribed a short course of pain relief medications to be administered by mouth.
In addition to this, your dog will need to be confined to strict cage rest. During this time, your dog may have a bandage on the affected leg, which should be carefully inspected daily to ensure there are no problems with it. Your veterinarian will give you specific instructions for the care and monitoring of any bandages used. It is important to follow these directions carefully and notify your veterinarian if you have any concerns, such as swelling or discharge, as these bandages can cause severe pressure sores or wounds.
Depending on your dog’s condition, your veterinarian may also recommend rehabilitation exercises such as passive range of motion (PROM), initially starting with regular movement of the toes, and may perform safe PROM on your dog’s hip joint when the bandage is replaced.
If your dog requires surgery, there are many techniques that might be used to repair the dislocation. A bandage or other support may be placed, and it will be necessary to confine your dog as directed by your veterinarian.
What is the long-term prognosis for my dog?
If the femoral head has been successfully replaced, the correct post-operative treatment has been adhered to, and the hip remains in place after 14 days, it is unlikely that the hip will dislocate again. The prognosis after most surgical re-placements is good. Careful rehabilitation is recommended to improve hip function and reduce future arthritis.
Dogs unable to have the joint successfully replaced will often limp or have limited use of the limb. As most of these cases will eventually require treatment for painful osteoarthritis due to their injury, other surgical procedures, called femoral head ostectomy (FHO) or total hip replacement (THR), may be recommended. See the handouts “Femoral Head Ostectomy in Dogs” and “Total Hip Replacement in Dogs” for more information on these procedures.