Understanding hip replacement

Hip arthritis, which can be caused by degeneration, inflammation and infection presents with pain in the hip joint. While the hip joint is surrounded by muscles, ligaments and tendons, symptoms including swelling and feeling of warmth in the joint are not noticeable.

Hip degeneration is commonly caused by developmental hip dysplasia and avascular necrosis of femoral head in our locality. The weight bearing cartilage is worn faster than the reparative process. The muscle, ligaments and bone around the hip are also affected. All these are the contributing causes of osteoarthritis.

Total hip replacement is a surgery to remove the worn-out or damaged bone and cartilage, and the affected joint is replaced with an artificial implant. The fixation of the implants can be done by either cemented or cementless method. An artificial joint consists of two components:

- Femoral implant is composed of ball head and femoral stem. The ball head is made of metal or ceramic and the stem is made of metal.

- Acetabular implant (bowl shaped) is composed of liner and metal cup in cemenless fixation. The liner is made of polyethylene ( commonly known as plastic ) or ceramic. A plastic cup is applied on cemented fixation.

Operation Procedure

1. According to the clinical condition, a surgeon will choose a surgical approach for performing total hip replacement, including posterior approach, anterior approach and lateral approach.
2. The femoral head is firstly dislocated from the acetabulum and then cut off.
3. Prepare the acetabulum surface which will be fixed to a suitable-size of acetabular implant.
4. Cancellous bone inside the femoral canal is removed. A suitable-size femoral stem is inserted to the femoral canal and fixed. An appropriate ball head is put on the stem.
5. The ball head is then fitted into the acetabulum cup. The hip joint mobility and stability are examined.
6. A drainage tube may be placed near the wound. The surgical wound is closed.
7. The lower limb will be bandaged if necessary.

General Complications

• Wound infection
• Post-operative chest infection
• Myocardial infarction
• Stroke

Surgical Risks and Complications

• Bleeding
• Nerve and vessels injury
• Prosthetic joint infection
• Joint dislocation
• Deep vein thrombosis and pulmonary embolism
• Limb length inequality
• Hip stiffness