The hip joint is a ball and socket joint that joins the femur to the pelvis. The ball is the head of femur, which inserts itself into the socket called the acetabulum of the pelvis. The hip joint supports a large part of the weight of the body and enables one to walk. When the hip joint is affected by arthritis, it becomes worn out and stiff and is unable to function. The affected person will experience pain and be unable to walk or walk with a limp.
Total hip replacement surgery is the treatment for osteoarthritis and rheumatoid arthritis of the hip. During total hip replacement surgery, the hip joint is removed and replaced using an artificial joint made of polyethylene, metal and ceramic. The femoral head is usually made of metal such as stainless steel and the acetabulum is usually made of polyethylene.
There are two approaches to total hip replacement, the anterior and the posterior approach. Each approach has its advantages and disadvantages.
In the anterior approach, the patient is lying on his back (supine). The incision is made over the greater trochanter of the femur which the side of the thigh, and the muscles are divided down to the hip joint. The surgeon must take care not to damage the lateral femoral cutaneous nerve which supplies sensation to the thigh, and the femoral nerve which innervates the quadriceps muscles of the thigh. The knee is bent, and the hip joint is dislocated anteriorly. During this procedure, there is a risk of fracturing the femur, especially if the bone is osteoporotic. After the joint is replaced, X-rays are taken to ensure correct leg length and position of the joint.
In the posterior approach, the patient is positioned on his side (lateral). The incision is made in a similar position as in the anterior approach and the incision length is also similar. However in this approach, it is the posterior gluteal muscles that are divided down to the bone. The surgeon must take care not to damage the sciatic nerve, which innervates the leg. The hip joint is dislocated posteriorly. The risk of fracturing the femur is lower, however, there is increased risk of posterior dislocation after surgery.
Although the posterior approach is quick and easy, the anterior approach is often more popular because it is thought that avoidance of cutting the gluteal muscles, which are the muscles that support the hip joint, reduces recovery times. In reality, the type of approach taken generally depends on the surgeon’s experience, skill and preference.
Possible complications after hip replacement surgery include infection, fracture, dislocation, nerve injury and the need for revision, e.g., due to differences in leg length. Medical complications after hip surgery include deep vein thrombosis and pulmonary embolism. After hip replacement surgery, physiotherapy is very important to be able to start walking again.