Hip Replacement: Total Hip Arthroplasty Explained

What is a Total Hip Replacement?

A total hip replacement (THR), also known as total hip arthroplasty (THA), is a surgical procedure in which the entire hip joint is replaced with an artificial prosthesis. The hip joint consists of the ball-shaped head of the femur (thigh bone) and the socket (acetabulum) in the pelvis. During a total hip replacement, both the femoral head and the acetabular socket are replaced with prosthetic components made of metal, ceramic, or plastic. This operation is one of the most frequently performed and successful orthopaedic procedures in the world, significantly improving the quality of life for patients suffering from severe hip conditions.

Causes and Indications

A total hip replacement is recommended when conservative treatments are no longer sufficient to control pain and when mobility limitations significantly affect daily life. The most common reasons for a hip replacement include:

• Osteoarthritis (hip arthritis): Progressive wear of the joint cartilage is the leading cause. As the cartilage breaks down, bone rubs on bone, causing severe pain.
• Rheumatoid arthritis: A chronic inflammatory joint disease that can destroy the hip joint over time.
• Avascular necrosis of the femoral head: Death of bone tissue in the femoral head due to impaired blood supply.
• Hip fracture: Particularly in older patients following a fall or trauma.
• Congenital hip dysplasia: Structural malformations of the hip joint present from birth.

Symptoms Indicating a Hip Replacement

Patients who may benefit from a total hip replacement typically experience the following:

• Persistent, severe pain in the hip, groin, or thigh, including at rest and at night
• Significant restriction of hip joint mobility
• Limping and changes in gait
• Pain when climbing stairs, sitting down, or rising from a chair
• Inadequate relief from pain medication and physiotherapy

Diagnosis

Before a hip replacement, a thorough diagnostic workup is performed to assess the severity of joint damage and to select the appropriate prosthesis:

• Physical examination: Assessment of range of motion, muscle strength, and pain distribution.
• X-rays: Standard imaging to evaluate joint wear and loss of joint space.
• MRI (Magnetic Resonance Imaging): Used when bone or soft tissue damage is suspected that is not visible on X-rays.
• CT (Computed Tomography): For precise planning of prosthesis positioning and sizing.
• Laboratory tests: To rule out infection or inflammatory disease before surgery.

Surgery and Prosthesis Types

Total hip replacement is usually performed under general or spinal anaesthesia. The surgeon accesses the hip joint through a lateral, anterior, or posterior approach, removes the damaged femoral head and acetabular cartilage, and implants the prosthetic components.

Fixation Methods

• Cemented prosthesis: Components are secured with bone cement. Particularly suitable for older patients with reduced bone quality.
• Uncemented (cementless) prosthesis: The implant has a porous surface that allows bone to grow into it over time. Preferred for younger patients with good bone density.
• Hybrid prosthesis: A combination of a cemented stem and a cementless cup, or vice versa.

Bearing Surfaces (Material Combinations)

• Ceramic on ceramic: Highly wear-resistant; suitable for younger, active patients.
• Ceramic on polyethylene: Good gliding properties; widely used.
• Metal on polyethylene: Well-established and cost-effective option.

Rehabilitation and Follow-up Care

Rehabilitation after a total hip replacement is essential for the long-term success of the surgery. Physiotherapy and gentle mobilisation exercises typically begin the day after the operation.

• First weeks: Walking training with crutches, muscle strengthening, and management of swelling. Certain movement restrictions must be observed (e.g., avoiding deep hip flexion).
• After 6–12 weeks: Gradual increase in activity, return to light daily tasks, and often discontinuation of crutches.
• Long-term rehabilitation: Physiotherapy, swimming, cycling, and other low-impact activities support muscle strength and joint mobility.

Regular orthopaedic check-ups are important to monitor the long-term function of the prosthesis. Modern hip replacement implants typically last between 15 and 25 years or longer.

Risks and Complications

Like any surgical procedure, total hip replacement carries certain risks:

• Prosthetic joint infection: A rare but serious complication that may require revision surgery.
• Deep vein thrombosis and pulmonary embolism: Blood clots in the leg veins; prevented through blood thinners and early mobilisation.
• Prosthesis dislocation: The hip can dislocate, most commonly in the first weeks after surgery.
• Leg length discrepancy: Slight differences in leg length may occur after surgery.
• Aseptic loosening: Over time, the prosthesis may loosen without infection, requiring revision surgery.
• Nerve injury: Rare damage to nearby nerves during the operation.

Outcomes and Prognosis

Total hip replacement is one of the most successful operations in modern medicine. More than 90% of patients report significant pain relief and improved mobility after surgery. The vast majority can return to an active, pain-free life after full rehabilitation. Modern implants typically last 15 to 25 years.

References

1. Learmonth ID, Young C, Rorabeck C. The operation of the century: total hip replacement. Lancet. 2007;370(9597):1508–1519. doi:10.1016/S0140-6736(07)60457-7
2. National Institute for Health and Care Excellence (NICE). Hip fracture: management. Clinical guideline CG124. London: NICE; 2023. Available at: https://www.nice.org.uk/guidance/cg124
3. Ethgen O, Bruyere O, Richy F, Dardennes C, Reginster JY. Health-related quality of life in total hip and total knee arthroplasty. Journal of Bone and Joint Surgery. 2004;86(5):963–974.