Hip replacement is a surgical procedure in which the hip joint is replaced by a prosthetic implant.
Hip replacement surgery can be performed as a total replacement or a hemi (half) replacement. Such joint replacement orthopaedic surgery generally is conducted to relieve arthritis pain or fix severe physical joint damage as part of hip fracture treatment. A total hip replacement (total hip arthroplasty) consists of replacing both the acetabulum and the femoral head while hemiarthroplasty generally only replaces the femoral head. Hip replacement is currently the most successful and reliable orthopaedic operation with 97% of patients reporting improved outcome.
Total hip replacement is most commonly used to treat joint failure caused by osteoarthritis. Other indications include rheumatoid arthritis, avascular necrosis, traumatic arthritis, protrusio acetabuli, certain hip fractures, benign and malignant bone tumors, arthritis associated with Paget´s disease, ankylosing spondylitis and juvenile rheumatoid arthritis. The aims of the procedure are pain relief and improvement in hip function. Hip replacement is usually considered only once other therapies, such as physical therapy and pain medications, have failed.
There are several different incisions, defined by their relation to the gluteus medius. The approaches are posterior (Moore), lateral (Hardinge or Liverpool), antero-lateral (Watson-Jones), anterior (Smith-Petersen) and greater trochanter osteotomy. There is no compelling evidence in the literature for any particular approach, but consensus of professional opinion favours either modified anterio-lateral (Hardinge) or posterior approach.
The posterior (Moore) approach accesses the joint through the back, taking piriformis muscle and the short external rotators off the femur. This approach gives excellent access to the acetabulum and preserves the hip abductors. Critics cite a higher dislocation rate, although repair of the capsule and the short external rotators negates this risk.
The lateral approach is also commonly used for hip replacement. The approach requires elevation of the hip abductors (gluteus medius and gluteus minimus) in order to access the joint. The abductors may be lifted up by osteotomy of the greater trochanter and reapplying it afterwards using wires or may be divided at their tendinous portion, or through the functional tendon (as per Hardinge) and repaired using sutures.
The anterolateral approach develops the interval between the tensor fasciae latae and the gluteus medius.
The anterior approach utilises an interval between the sartorius muscle and tensor fascia latae.
Mimimally invasive approach
The double incision surgery and minimally invasive surgery seeks to reduce soft tissue damage through reducing the size of the incision. However component positioning accuracy is impaired and surgeons using these approaches are advised to use computer guidance systems.
Computer Assisted Surgery techniques are also available to guide the surgeon to provide enhanced accuracy and visualization. Several commercial CAS systems are available for use worldwide. HipNav was the first system developed specifically for total hip replacement, and included navigation and preoperative planning based on a preoperative CT scan of the patient.