Anatomy and Function of the Hip

The hip, a ball-and-socket joint, is the largest weight bearing joint in the body. When the joint is healthy, the head of the femur (thighbone) forms a round ball that fits in to the acetabulum, a cavity at the base of the pelvis that forms the socket.

Ligaments connect the ball to the socket and keep them both firmly supported. The surfaces of the femoral head and the acetabulum are covered by a smooth, tough material known as articular cartilage, which cushions the bones and allows them to move easily. Around the rim of the acetabulum is a layer of fibrous cartilage called the labrum, which deepens the socket and provides a suction seal to hold the head of the femur firmly in place.

Other surfaces of the hip joint are covered by a thin, smooth tissue liner called the synovial membrane. This tissue produces a small amount of synovial fluid that acts as a lubricant and reduces the amount of friction that occurs when bones move against each other.

Hip Conditions and Treatment Options

The most common cause of chronic hip pain and disability is arthritis. Osteoarthritis, rheumatoid arthritis, and traumatic arthritis are the most common forms of this disease. Osteoarthritis is an age-related “wear and tear” type of arthritis, where the cartilage cushioning the bones of the hip wears away. When the bones \ rub against each other, it causes hip pain and stiffness. Rheumatoid arthritis is an autoimmune disease in which the synovial membrane becomes inflamed or thickened. This chronic inflammation can damage the cartilage, leading to pain and stiffness. Post-traumatic arthritis can follow hip injury or fracture. The cartilage may become damaged and lead to hip pain and stiffness over time. An injury to the hip, such a disclocation or fracture, may also limit the blood supply to the femoral head, causing osteonecrosis. The lack of blood may cause the surface of the bone to collapse, leading to arthritis. Some diseases may also cause osteonecrosis.

Labral Tears of the Hip

The labrum is a layer of fibrous tissue covered in a synovial membrane that lines the rim of the socket in which the ball of the femur sits. This cartilage provides cushioning for the joint and keeps the femur in place. A tear in the labrum can result either from injury or from degeneration. Labral tears can be painful and may cause symptoms such as locking or “catching” in the joint and pain in the hip or groin area. Since labral tears are often difficult to detect during a physical examination, a doctor may use magnetic resonance imaging (MRI) with a dye injection to confirm the diagnosis.

Total Hip Replacement

In a total hip replacement, also called total hip arthroplasty, damaged bone and cartilage is removed and replaced with prosthetic components. The damaged femoral head is removed and replaced by a metal stem that is placed into the hollow center of the femur. The femoral stem may be either cemented or “press fit” into the bone. A metal or ceramic ball is placed on the upper part of the stem. This ball replaces the damaged femoral head that was removed. The damaged cartilage surface of the socket is removed and replaced with a metal socket. Screws or cement are used to hold the socket in place. A plastic, ceramic or metal spacer is inserted between the new ball and the socket to allow for a smooth gliding surface. There are no age or weight restrictions for this procedure.

Anterior Hip Replacement

Direct anterior hip replacement is a minimally invasive surgical technique. This approach involves a 3 to 4 inch incision on the front of the hip that allows the joint to be replaced by moving muscles aside along their natural tissue planes, without detaching any tendons. This approach often results in quicker recovery, less pain, and more normal function after hip replacement. Because the tendons aren’t detached from the hip during direct anterior hip replacement, hip precautions are typically not necessary. This allows patients to return to normal daily activities shortly after surgery with a reduced risk of dislocation. Not all patients are candidates for direct anterior hip replacement, with the major restrictions being body weight (body mass index greater than 35) and complex hip disorders (e.g. hip dysplasia, previous surgeries, etc.)

MAKOplasty Total Hip Replacement

MAKOplasty® Hip is an innovative total hip replacement procedure that is performed using a highly advanced, surgeon-controlled robotic arm system. It can be a treatment option for people suffering with either non-inflammatory or inflammatory degenerative joint disease. The goal of using robotic arm technology to perform hip replacement is to provide the utmost in accuracy for placement and alignment of implant components. The use of robotics helps your surgeon place the implants in the desired location with incredible accuracy, providing an excellent, stable biomechanical reconstruction and unprecedented leg length restoration. It is performed with the RIO® Robotic Arm Interactive Orthopedic System. RIO enables your surgeon to use a 3-D anatomic reconstruction based on a CT scan of your own hip to pre-surgically plan implant positioning. During the procedure, it provides real-time data for intra-operative adjustments to further enable me to optimally align and position implants, and accurately reproduce the surgical plan. Your surgeon will determine if you are a good candidate for this procedure, based on the specifics of your condition.