The hip is a ball-and-socket joint. The socket is formed by the concave surface of the pelvis called acetabulum which is also a part of the large pelvis bone. The ball, on the other hand, is the femoral head which is part of the upper femur (thigh bone). Both the ball and the tissue are covered by the slippery tissue called articular cartilage.
The acetabulum is ringed by the fibrocartilage called the labrum which forms a gasket around the socket. Overall, the joint is surrounded by the fibrous connective tissue called ligaments. They form a capsule that holds the joint together. The underside of the capsule is lined by the thin membrane called the synovium which is responsible for producing synovial fluid. The synovial fluid is what lubricates the hip joint.
The ball normally glides smoothly within the socket, but an odd growth around the hip socket or femoral head can interfere with the smooth motion of the ball. This problem is what causes hip impingement and is believed to be a major cause of early osteoarthritis, particularly those ages is below 40.
The symptoms of the hip impingement are usually not painful in the early years. The symptom is usually referred to as hip impingement syndrome; stiffness in the groin or in the front of the thigh are usually felt by the patient. In addition, loss of hips full range motion, as well as pain during night hours and when walking on flat grounds, sums up as hip impingement syndrome.
Causes of Hip Impingement
There are two reasons for hip impingement. First is the cam impingement and pincer impingement is the second. The former is the deformity of the ball at the top of the femur which may occur when the hip is bent. Activities like tying the shoes or bicycling may cause pain for the hip.
Pincer impingement is a deformity of the socket. It is when bone growth causes the socket-shaped acetabulum to extend too far over the femoral head. If the rim of the hip socket sticks out, it may pinch the labrum during movement and cause it to tear.
Moreover, there are cases where both socket and ball have deformities.
Below are some of the conditions that can cause hip impingement:
- Legg-Calve-Perthes Disease: is a disease in which there is not enough blood supply coming to the ball part of the hip joint and it causes the bone to die.
- Slipped Capital Femoral Epiphysis: is a condition common to obese children. It is when the ball separates from the thigh bone at the upper growing end (growth plate).
- Coxa Vara: is an abnormal growth of bone in children. The condition shows that the thigh bone and ball do not grow at the same pace. This leads to deformity of the hip joint.
The pain that is experienced in hip impingement needs treatment. There are two types of hip impingement treatment.
The first one is the nonsurgical type. It includes:
- Resting the impinged hip
- Modifying the activities that might result in further damage to the hip
- Doing exercises that are recommended by doctors or physical therapist to support the hip or strengthen the muscles; and
- Taking medication and/or painkillers.
If a nonsurgical method does not work, that is if it does not relieve the pain, the doctors would recommend hip impingement surgery.
There are various types depending on the problem that is causing hip impingement and how much cartilage damage has occurred.
The first type is microfracture surgery, but this is being used less often nowadays. In this technique, the surgeon may cut away frayed cartilage that is causing pain. They may also drill holes into patches of bone where cartilage has worn away. The technique may stimulate cartilage growth.
Arthroscopy is another method that surgeons use to correct hip impingement. They will cut a small incision at the side of the hip and use small tools like arthroscope (a small camera) to access the insides of the hip. The arthroscope is controlled by the surgeons and they can easily identify what is wrong with the hip using this camera. After identifying the problem with the patient’s hip, the surgeons will use other miniature surgical instruments to fix the hip. Hip arthroscopy has been performed for many years. This is commonly conducted to outpatient which means that the patient can go home the same day the surgery occurred.
Surgical Hip Dislocation
Surgical hip dislocation is often suggested by surgeons if they confirm that large bone growths have developed on the acetabulum. They may also do this same procedure if the labrum has been torn. Surgeons carry out surgical hip dislocation by making a cut at the side of the hip. They will then move aside the small part of the upper femur so that the surgeons can better access the hip joint. The bone fragment will be put back into place after the joint has been repaired.
Ganz osteotomy is a procedure to reposition the acetabulum. It is also known by the name periacetabular osteotomy and it provides more stability if you have a developmental hip dysplasia.
There is a procedure for cam impingement called femoral osteoplasty where the femur is reshaped to better fit the hip socket. It is the surgeon’s decision, based on the results of the diagnostic imaging tests, if the procedure is deemed appropriate.
During the procedure, the surgeon makes a cut on the front of the hip to access the joint. He separates the acetabulum from the rest of the pelvic bone. The acetabulum is then rotated, so it matches the alignment of the femoral head. This new position is fixed with metal screws. Lastly, the doctors will close the incision with stitches or staples.
Surgeons may recommend hip replacement if the damage in cartilage is identified as severe. This treatment can relieve the hip pain and restore the normal hip mobility.
Complications for hip impingement surgery are very uncommon; however, any surgery in the hip joint carries a small risk of injury to the nearby blood vessels or nerves, or the joint itself. Small risks of infection, as well as blood clots forming in the veins, are the only other risk that surgeons and patients should consider.
Though after the successful hip impingement surgery, the patient is highly expected to felt no pain in the hip area and he/she has better range of motion.