Total Hip Arthroplasty
Scott M. O’Connor, MD

There are over 150,000 total hip arthroplasties (THA) performed in the U,.S. each year. The first THA was performed in 1960, and millions have undergone this procedure and experienced the relief from chronic pain that this operation can provide. Subsequent technological advances in implant design and surgical technique have contributed to the growing number of successful procedures each year, This article will explain normal hip function, how it is affected by arthritis, and will give you some of the information that you need to help you decide if THA might be appropriate for you.

Hip Function
The hip is a “ball and socket” joint responsible for bearing a significant amount of weight applied from the upper body. It is supported and held together by muscles and ligaments and the joint capsule. The joint is cushioned by cartilage, which is rubbery in texture, and allows low friction gliding of the joint. The synovial membrane surrounds and lines the hip, and secretes a lubricating fluid. As arthritis progresses, the cartilage thins and deteriorates, causing the sensitive bony surfaces to become irritated and painful. With time and disease progression, the surrounding tissues provide less support, the joint becomes more damaged and the pain becomes more intense. The most common type of arthritis is osteoarthritis, which usually begins in middle age, and results from wear and tear on the articular cartilage. Rheumatoid arthritis is caused by an inflammatory condition in which the synovial (fluid-producing) lining of the hip excretes the articular cartilage. Lastly, arthritis can occur after trauma to the hip (such as a fracture or severe fall), which may cause irregularity in the smooth surfaces of the joint, or lead to avascular necrosis, which causes severe damage to the bony support areas of the hip.

Signs and Symptoms of Hip Arthritis
As the hip becomes more and more arthritic, the articular cartilage cracks and wears away, causing the bony surfaces to rub together. This wears down the ball and socket and causes stiffness and pain. The symptoms are initially worse while standing, walking or when rising from a sitting position. Often patients will notice that it “takes a few steps for the hip to feel right”. Fragments of cartilage may loosen and cause an unpleasant “grinding” or “sandpaper” sensation within the joint. As the disease progresses with time, groin, buttock or upper thigh pain can become severe even at rest, and may cause difficulty falling asleep. Normal daily activities such as sitting, standing, bending or even walking short distances can present a significant challenge.

Treatment Options
Initial treatment for patients with hip arthritis may include pain medication such as Tylenol, or non-steriodal anti-inflammatory drugs (NSAIDs) such as ibuprofen or Aleve. Other options such as a cane or walker, physical therapy, rest and life-style modification can be considered. Surgical treatment is considered when non-operative management fails to relieve pain and improve mobility. Your orthopedic surgeon will determine if you are a candidate for THA after performing a thorough history and orthopedic examination, including hip x-rays. You may be asked to see your primary care doctor preoperatively to assess your general medical condition. Autologous (self) blood donation for later transfusion is also an option for most healthy people.

The Procedure
Prior to the procedure, either general or spinal anesthesia is given. Epidural (continuous spinal) anesthesia can be used, and can provide one to two days of ongoing pain relief. The total hip arthroplasty operation replaces both the femoral head (ball) and the acetabulum (socket). The femoral implant (prosthesis) is usually made of a strong metal, while the acetabular component is made of a similar material lined with the polyethylene (strong plastic) cup. These components are selected due to their high strength and low friction (wear and tear) properties. The acetabular component is usually “press-fitted” into place in the socket using precision instruments. Most often, the femoral prosthesis is held in place with a special surgical cement to bridge the gap between the femoral stem and thigh bone. A non-cemented (press-fitted) femoral prosthesis may be used in the younger, more active patient. Your orthopedic surgeon will decide which prosthesis best suit your physical condition and lifestyle. The operative procedure normally takes about two to three hours.

Postoperative Recovery
Some pain naturally occurs for a few days after surgery, but can be adequately controlled with pain medication. Physical therapy usually beings the next day, and includes gait training and hip muscles strengthening exercises. In order to minimize the potential risk of blood clots, blood thinners and support hose may be used. Discharge planning is a coordinated effort between the patient, physician and the hospital Social Service associates, and a variety of options are available to meet various short- to medium-term patient needs.

Results
The results of THA are noteworthy. Ninety percent or more of patients report good to excellent outcomes, with a dramatic decrease in hip pain and stiffness. Most patients can return to normal activities within about 6-8 weeks postoperatively. In order to achieve a good result, a strong commitment to full participation in the recovery process is very important. It is not unusual to see fully functional hip replacements 15 to 20 years after surgery, and continuing advancements in research and surgical techniques may further increase the lifespan of this remarkable procedure.

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