Hip dysplasia and resulting hip osteoarthritis is a common condition in some of the medium to larger breeds of dogs. Often, these dogs can be relatively asymptomatic, but for some, this condition results in significant loss of comfort and function. The hip joint consists of a socket (the acetabulum), and the head of the femur (the “ball”). Normally, these two components fit together tightly and allow for a normal range of motion in flexion, extension, and rotational movements. But, in hip dysplasia, there is excessive play or laxity in the structures that support the hip, leading to wear and tear on the joint cartilage surfaces, and exposure of the underlying bone. As the condition progresses, osteophytes (bone spurs) are formed, the socket fills in with fibrous tissue and bone and the joint capsule that surrounds the femoral head thickens. These changes result in reduced range of motion and exposure of nerve endings in the bone to abrasion that causes pain.
Some of the symptoms of hip osteoarthritis include difficulty jumping or rising from sitting and lying positions, reluctance to climb stairs or jump into the car or furniture. Affected dogs can exhibit a “bunny hopping” gait, and may not sit squarely on their back legs, preferring to roll to one side instead. Play activity may decrease, and they may act grouchy when handled around the hips. Unfortunately, there are several other conditions affecting the rear legs that can mimic these symptoms including torn cranial cruciate ligaments, pain in the lower lumbar spine or other progressive neurological conditions affecting the spinal cord.
Fortunately, there is help for dogs affected by hip pain from osteoarthritis. First, a diagnosis needs to be made by your veterinarian. This will involve a physical examination and x-rays of the pelvis, if indicated. If you look at the x-ray below, we can see a pelvis of a young dog with hip dysplasia and significant laxity. In the second x-ray, we see a dog with more advanced arthritis in the hip joints secondary to hip dysplasia.
Treatment Options:
Medical management can be considered in the early stages to see if the dog can derive relief from pain thus restoring reasonable function. Medical management consists of weight management if overweight – excess weight can put a huge burden on the hips. In addition, pain can be managed with a combination of anti-inflammatory drugs (NSAIDS – of which there are a number safe for dogs), Joint support supplements like glucosamine and chondroitin sulfate, and omega-3-fatty acids (fish oils). Controlled and regular activity can maintain muscle mass and mobility but should avoid excesses. Physical therapy such as underwater treadmill exercises can also help maintain mobility and strength. The goals of medical management are mostly directed at managing mild to moderate disability and likely will not work adequately on the severely affected, or in high performance dogs.
Surgical options are directed at pain control and mobility. There are several options for young dogs, which we will not cover in this article. There are two options for mature dogs that we will discuss here – Femoral head and neck excision (Femoral head Ostectomy or FHO) and Total Hip Replacement (THR).
In FHO, the femoral head and neck is removed, leaving a gap between the femur and the socket (acetabulum). Movement of the leg remains because the muscles that move the hip joint attach around the upper femur and not on the head. This procedure restores greater mobility and reduces the painful contact of worn bone on bone. FHO does not restore normal function and is best directed at smaller patients that can adapt better to this procedure. It can be done in larger patients when THR is not an option. Post-operative physical therapy is helpful in regaining and maintaining mobility and range of motion. There are few complications from this procedure, but the recovery is relatively long to reach an acceptable endpoint (several months)
Total Hip Replacement (THR) – In THR, the two components of the hip are replaced much as it would be in a human patient. First, the head of the femur is removed. The Acetabulum is then ground down to create a healthy bony socket and a titanium and plastic “cup” is impacted into the bony cavity. The femoral side is then prepared by progressive enlargement of the canal with “broaches” that prepare a precise cavity inside the femur to accept the “endoprosthesis” which is the stem that will have the replacement head. That implant is then impacted into the prepared canal with a press fit. Both metal components are made with a porous surface designed to allow the dog’s bone to grow into the metal resulting in a permanent bond between the implant and the bone. This “ingrowth” process takes about 6 to 8 weeks to fully mature. Below, you can see a finished total hip replacement performed on a dog with advanced hip arthritis. The left hip has been replaced and has healed nicely with bony ingrowth into the metallic surfaces.
The THR procedure is technically demanding of precision and accuracy by the surgeon. Careful selection of cases is imperative to best assure a good or excellent outcome. Indications include severe osteoarthritis in the hip, fractures of the femoral head, and dislocation of the femoral head where the acetabulum is poorly formed, and restoration of the joint is not likely to be possible. Contraindications to performing a total hip replacement include chronic infections of the bladder or skin, concurrent orthopedic conditions such as unrepaired cranial cruciate ligament injuries or neurological conditions with significant impact on function. Medical conditions such as Diabetes or Cushing’s disease can be relative contraindications as well.
Postoperative instructions are directed at protecting the hip from dislocation, femur fractures or dislodgement of the implant from its bed in the femoral canal. That consists of an 8-to-12-week confinement period and leash-controlled walks. At Pittsburgh Veterinary Specialty and Emergency Center, our surgeons regularly perform THR with excellent results. Successful outcomes can result in complete resumption of an active lifestyle for these dogs. Many of these dogs will return to police work, hunting, or running with their humans.
