Total Hip Replacement (Total Hip Arthroplasty)

Anatomy of Hip Joint:

The Hip is a ball (referred to as femur head)-and socket (referred to as acetabulum) type of joint that enables your leg to move forwards, backward and sideways. Soft tissue called cartilage covers this joint to ensure the movement of the ball-and-socket is smooth. When the movement of the ball-and-socket is rough/not smooth (due to conditions mentioned below), routine activities are painful. 

Why Is It Done?

Recommended when the Hip Joint is damaged to interfere with one's daily routine activities to the extent that it can not be corrected or managed non-surgically

• persistent pain
• pain that worsens on walking
• causes disruption in sleep
• makes standing-up difficult
• pain while climbing a flight of stairs

Conditions that make one more prone to hip damage requiring surgical intervention include:
1. Osteoarthritis: ‘Wear and Tear Arthritis' The cartilage which cushions/cover the joint gets damaged, causing hip pain and stiffness
2. Rheumatoid Arthritis:  'Inflammatory Arthritis' Autoimmune disease wherein prolonged (chronic) inflammation damages the cartilage, eventually causing hip pain and stiffness
3. Osteonecrosis: ‘Avascular Necrosis. An injury/fracture or dislocation may limit the blood supply, which damages the hip joint, causing arthritis
4. Post-Traumatic Arthritis: Hip injury or fracture may damage the joint, requiring surgical intervention
5. Childhood Hip Disease: Hip does not grow normally affecting the joint surfaces hence hip replacement surgery may be needed to rectify the condition

Types of Hip Replacement Surgery:
1. Total Hip Replacement: 'Total Hip Arthroplasty' A plastic cup replaces the socket of the joint (may or may not include a titanium shell), and a ball made of ceramic or metal alloy replaces the femoral head. This is the most common type
2. Partial Hip Replacement: 'Hemiarthroplasty' Only one side of the hip is replaced - the femoral head - instead of both sides compared to total hip replacement. Recommended in older patients with a fractured hip
3. Hip Resurfacing: ‘Surface Replacement’ This procedure involves preserving more of the natural bone by retaining the natural femoral head. The femoral head is resurfaced to fit a metal cap with a short stem. Commonly done in younger, active  patients 

Surgical methods of Hip Replacement involve the following approaches:
1. Direct Anterior Approach: An incision is given on the front of the hip
2. Anterolateral Approach: An incision is given on the side of the hip, towards the front of the body
3. Posterolateral Approach: An incision is given on the side of the hip, towards the back of the body
Based on the condition, the surgeon decides which approach would be minimally invasive to access the hip joint in 1 or 2 small incisions. 

Steps to Hip Replacement Surgery:

Pre-Surgery:

The patient’s medical history is taken, and a physical examination is done. Blood tests and X-rays may be prescribed by the doctor. Tobacco interferes with the healing process. Discontinue the use of tobacco for at least a month before a scheduled surgery. Avoid dental work two weeks before surgery.

Surgery: 
Typically, the procedure lasts a few hours. An IV line is inserted in the hand or arm. A urinary catheter is also inserted.  Anaesthesia is administered. The type of anaesthesia  (general anaesthesia, spinal block, epidural block, or regional nerve block) is determined by the anesthesiologist and the orthopaedic surgeon. Based on the type of surgical approach, the patient is appropriately positioned for easy access to the hip joint, and an incision is made. Layers of tissues are cut to access the hip joint and the damaged/diseased bone and cartilage are removed.

The head (ball) of the femur is removed, and an opening is made on the top of the femur. The stem of the ball prosthesis is then inserted with or without cement. Likewise, the prosthetic socket is inserted into the pelvic bone. A tube is placed in the hip for drainage before closing.

Layers of tissue are stitched back with dissolvable stitches, and skin is closed with surgical glue. 

Post-Surgery:
Moved to the recovery room, where vitals are monitored. After the anaesthesia wears off and if the vitals are stable, the patient is moved to their allocated hospital room. Pain medications are prescribed to manage the pain. Patients are encouraged to get up and move around as soon as possible post-surgery with the support of a cane, walker, or crutches (to prevent blood clots). Physical therapy/rehabilitation is recommended to regain muscle strength and a good range of motion. 
 

Recovery period post-surgery:

During the recovery period, the patient should

• Ensure the surgical site is clean and dry
• Take medications, diet as prescribed
• Attend physical therapy and do home exercises
• Elevate the leg and use ice to control the swelling
• Driving after full recovery noted as per the doctor

Risks associated with Hip Replacement:

• Blood clots: Can be prevented by - moving early post-surgery, taking blood-thinning medications, applying pressure by wearing elastic compression stocking or inflatable air sleeves
• Infections: Most often treatable by antibiotics. However, a significant disease near the implanted prosthesis may require removing and replacing the prosthesis
• Fracture: May heal on their own or may need to be stabilized with wires, screws or metal plate
• Dislocation: You may be fitted with a brace to ensure the hip stays in the correct position
• Leg Length changes: Post muscle strengthening, this may not be noticeable
• Nerve damage: Occurs rarely. 
• Loosening of the prosthetic joint may occur for not being solidly fixed over the bone, or this may happen over a while. However, with better prosthetics, this is rare. 

Questions To Ask Your Doctor Regarding Hip Replacement Surgery

Although the below questions have a generalized answer, every patient and their condition is different. Make sure you ask your doctor the following 

1. Expected time until full range of leg movement (generally it takes up to 2 years)
2. How long will the hip implant last effectively (generally, it is 10-20 years, but some may last longer)
3. How long is physical therapy expected to last?
4. When can one resume driving? (generally, it is six weeks post-surgery)
5. How long will the hospital stay be? (generally, it is 2-3 days)