Hip anatomy

Hip joints are composed of the femur (the long bone of the thigh) and the acetabulum (the socket found in the pelvis). Hips are ball and socket joints, which allow the lower extremity to move in three different planes of motion as well as providing stability during weight bearing activities. Hips also function as shock absorbers for the upper part of the body. In an average year each hip can complete approximately 1.5 million steps as well as countless other movements.

Bones

The head of each femur is shaped like a ball and fits tightly into the sockets (cup-shaped depressions) in the pelvis, allowing the legs to move forward and backward, side to side and rotate right to left.

Cartilage

The acetabulum is lined with cartilage which acts as a cushion for the bones and allows the joint to move smoothly.

Ligaments

A complex system of ligaments hold the femur tightly into the acetabulum and stops the hip from moving outside of its normal range.

Muscles

The muscles in the hip are jointly responsible for providing the power for the hips to move as well as stability to the lower extremities during movement.

Conditions that lead to hip replacement

The most common cause of pain and problems in the hip joint are two types of arthritis. Arthritis causes the cartilage to wear away causing the head of the femur and the inside of the acetabulum to run against each other without any lubrication or cushioning. When this happens, the bone becomes pitted, eroded and uneven, restricting movement and causing pain and stiffness. The other most common cause of hip replacements is unrepairable fractures.

Osteoarthritis

Osteoarthritis is a degenerative disease that most often occurs in patients over the age of 50, but can occur at any age if the hip joint has been damaged. Patients with osteoarthritis often develop bone spurs around the joint, which severely limit motion. It is also known as wear and tear arthritis, because the joint just wears out.

Symptoms

  1. Pain in the hip or groin area during weight bearing activities i.e. walking
  2. Limping to reduce the pain on the afflicted hip
  3. Loss of flexibility
  4. Pain which increases and eventually is present even when the patient is not doing weight bearing activities

Treatment

Non surgical therapies can be instated under the medical guidance

  1. Weight loss helps to decrease the force across the hip joint
  2. Physiotherapist prescribed exercise to improve strength and flexibility of the hip, knee and ankle joints
  3. Non-steroidal anti-inflammatory drugs and/or nutritional supplements (chondroitin/glucosamine) may help to reduce the pain
  4. Assistive devices like a cane or a crutch may also help reduce the force on the affected hip while walking

Surgery

If none of these treatments help, and the patient suffers from continually increasing pain and loss of motion, then hip replacement surgery might be the best available option.

Fractures

Fractures are the second most common reason hips are replaced. In older patients it is not always possible or advisable to pin the bones, and expect them to knit. When age is a factor, a full replacement might be strongly recommended.

Rheumatoid arthritis

Unlike osteoarthritis, which is a “wear-and-tear” cause of hip damage, rheumatoid arthritis is a chronic inflammatory condition that effects the joints and results in pain, swelling and stiffness. It can progress to the point where there is deterioration of multiple joints simultaneously, resulting in severe pain and loss of mobility. Although the exact cause of rheumatoid arthritis is not known, the onset of this disease most frequently occurs in middle-age and is most common among women.

Symptoms

  1. All the same symptoms as osteoarthritis
  2. Loss of appetite
  3. Fever
  4. Energy loss
  5. Anaemia
  6. Rheumatoid nodules (lumps of tissue under the skin)
  7. Flare-ups where multiple joints may be painful and stiff

Treatments

  1. Non-steroidal anti-inflammatory drugs, aspirin and anaelgesics
  2. Corticosteroids may be prescribed to help the decrease of inflammation, but must be closely monitored by a physician.
  3. Disease modifying agents like methotrexate, are now available as a result of research.

Surgery

If none of these treatments help, then hip replacement surgery might be the best available option to relieve the pain and help the return of an improved functional level