Dogs and cats have a high reported incidence rate of hip luxations, among the common causes are hip dysplasia, abnormally shallow hip joints, traumatic luxations and fractures involving either the femoral neck or femoral head. Often theses cases present as an acute loss of hindlimb function, with the patient often holding the affected leg up and walking on the other 3 unaffected legs. While the pain usually reduces significantly within 24 hours, they are still unable to bear weight on the affected leg even after pain medications.
Owing to the physical nature of this disease resulting in the femoral head/neck to be out of the hip joint, treatments are mainly focused on procedures to replace back this joint to its weight bearing position, either conservatively or surgically. Conservative treatments are usually attempted within 48 hours of the injury, with radiographs to determine the direction of luxation, sedation to pull the muscles and reduce the hip back into the joint, followed by assessment of stability. Some of this cases are successful in reducing the luxation and be followed with bandage for 2 weeks to allow the swelling and inflammation to subside. If the patient is lucky, this solves the problem albeit chances of relaxation is going to be higher compared to a normal hip.
Toggle pin concept
Cases where reduction is not achievable or unstable (hip re-luxates the moment rotation is applied to the leg), surgical options remains the main choice to help restore function and resolve pain. In cases where the hip ball and socket structure is normal, luxation occurs due to a rupture of the round ligament holding the joint together. Reduction is performed surgically followed by a toggle pin prosthesis ligament to help keep the joint in place. This usually provides a good restoration of function but due to the manipulation of the joint, arthritic changes may occur after a certain amount of time, and long term medical management for this may be required.
Abnormal Hip (avascular necrosis)
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Quite often the hip is luxated due to an abnormal hip joint to begin with, or due to a heavy traumatic incident, putting the hip back will not solve this issue as it is an abnormal joint to begin with. Shallow socket, early onset arthritis & instability of the joint post reduction makes the joint non functional even if its able to be reduced. In these cases, Excisional Arthroplasty (or Femoral Head & Neck Ostectomy, FHO) can be done as a salvage procedure to resolve pain and restore functional mobility to the leg. Principle of this surgery is to remove the femoral head and neck of the luxated joint so it doesn’t cause further pain from impingement of muscle or bone, and relying on the gluteal muscles alone to support weight. Done relatively commonly, this procedure provides satisfactory outcome when the gluteal muscles develop sufficiently to support the patient’s body weight. Due to the limitation of the muscles, this procedure is often only recommended for patients below 25kg and not obese. The patient can walk and run relatively well after FHO but will have a restricted range of motion and owners will need to make sure the dog/cat doesn’t become overweight.
In light of recent research, all these described techniques of treating hip luxation does restore function, but the patient will usually have some retained discomfort at a certain angle of the leg, or reduced function of the hindleg as compared with dogs with normal hips, more so in a cat patient. Dogs above 25kg have a limited option as well.
Total Hip Replacement (THR) is the best option that allows restoration of a normal hip joint, giving full recovery of hip function and the patients stay pain-free for the rest of their lives. This holds true both for human as well as veterinary patients. Advancements in the veterinary THR implants helps to improve surgical outcome and patients’ quality of life. Cats & Dogs ranging from 1kg – 90kg can have the option of a THR nowadays with this option now available to pets in Malaysia. Given the choice, all problematic hip joints can be surgically replaced to allow normal function again for the rest of their lives. Cost remains the main hurdle why so many patients are not given this option, with hip replacement prices ranging from RM17’000-20’000 for 1 side.
THR post op Xrays
Conclusion
Ultimately, all hip problems are different and unique. Patients need to be assessed clinically and examined radiographically to determine what treatment options can be offered. This article is meant to be educational and kindly seek consult from your trusted vet on this matter before deciding what’s best for your pet.