ARTHROSCOPIC TREATMENT OF FEMOROACETABULAR IMPINGEMENT IN PATIENTS WITH CHRONIC HIP PAIN

Femoroacetabular impingement is, according to the latest evidence in the current literature, the commonest cause of chronic hip pain in patients without osteoarthritis. Patients in this group are usually young and highly active in sport, typically taking part in sports that involve a large range of movement of the hip joint. These patients very often complain of hip pain (Figure 1) that is related to activity and, as the condition worsens, the pain may also appear on sitting, at rest and, in advanced cases, during sleep. It has not been established whether this condition is a congenital abnormality or whether it develops over the course of a person's life, chiefly during intense athletic activity.
Femoroacetabular impingement, or abutment, essentially consists of abnormal contact between the two articular surfaces of the hip. The hip is made up of two bones, the femoral head and the acetabulum. In a normal hip, movement between these two articular surfaces takes place freely, without the non-articular surfaces coming into contact. In femoroacetabular impingement, however, one of the two bones has an anatomical variant or abnormality, so that there is excess bone in certain areas, and this leads to abnormal impingement between these two parts of the joint. In some patients the lesion is present only in the acetabulum and in others it lies in the femur. It is very common, however, for patients to have both forms of femoroacetabular impingement.
When the lesion involves the acetabulum, it is called pincer-type femoroacetabular impingement (pliers-like). When the lesion lies in the femur, it is called cam-type femoroacetabular impingement (Figure 2). In a pincer lesion the acetabulum, which receives the femoral head and has a concave shape, has a prominence of its anterior part that impinges on the femur during deep flexion. In a cam lesion the problem lies at the head-neck junction, that is, at the point where the femoral neck meets the femoral head (Figure 3). Indeed, in this case the radiographic appearance of the femur resembles the grip of a pistol (pistol grip deformity). In both cases the effect of the abnormal movement of the joint is the same and, naturally, so are the patient's symptoms. Accurate diagnosis of these two lesions requires a thorough clinical examination of the patient together with appropriate imaging, with radiographs and MRI of the hip.
Besides being a cause of chronic pain in patients, femoroacetabular impingement is regarded by many authors as a precursor of wear of the hip, that is, of osteoarthritis. In theory, femoroacetabular impingement gradually wears away the labrum of the acetabulum, and over the years this wear spreads to the articular cartilage of the acetabulum and later to that of the femoral head. The end result is destruction of the joint. This theory has not, however, been proven in practice, although there is a good deal of evidence for it in the literature. For this reason, surgical treatment of the joint is recommended only in symptomatic patients and not as a means of preventing wear of the joint.
In the past, the condition was treated with open surgical techniques in which a large incision was made, the joint was opened, the hip was dislocated and the lesions were then removed. These operations gave good results but, because they were so invasive, they caused considerable morbidity for the patient and were followed by a long period of rehabilitation. Today the best and least invasive technique is considered to be arthroscopic treatment. In the arthroscopic technique the instruments are introduced through two or three small openings in the skin, and it is possible to inspect the whole joint and identify the femoroacetabular impingement lesion. The aim of arthroscopic treatment is to remove the excess bone, either from the acetabulum, that is, in a pincer lesion, or from the head-neck junction, that is, in a cam lesion. The ultimate objective is the removal of bone, which is carried out with the arthroscopic burr (a small rotating cutter).
This video shows the three main stages of the arthroscopic treatment of cam-type femoroacetabular impingement in a patient with chronic hip pain. The first stage shows identification of the cam lesion, with a view of the anterior surface of the head-neck junction and the femoral bony overgrowth. At this stage the severity of the lesion must be assessed, and the point at which the weight-bearing articular surface of the femoral head ends and its non-weight-bearing area begins must be noted. In the second stage the soft tissues over the non-weight-bearing surface of the femoral head are cleared, so that the area of the cam lesion can be marked out. Careful clearance of the soft tissues is very important, so that the bone is exposed and the lesion can be assessed in detail. In this second stage, once the femoral bony overgrowth has been exposed, the excess bone is removed with the arthroscopic burr. Correct assessment is important, because it leads to correct removal of bone, that is, to the depth at which the surgeon will place the arthroscopic burr. The third stage shows the reshaping of the head-neck junction, which should now resemble the head-neck junction of a normal hip. The third stage is completed by clearing the remaining soft tissues and smoothing the surface from which bone has been removed, in order to ensure that the joint now functions smoothly.
The arthroscopic technique for femoroacetabular impingement has all the advantages of minimally invasive surgical techniques and of a rapid return of the patient to their usual activities. This operation does not usually require a stay in hospital, or in some cases only one overnight stay. From the same day the patient can walk and go up and down stairs. Naturally, as with all orthopaedic operations, arthroscopic removal of a femoroacetabular impingement lesion is followed by a programme of physiotherapy and rehabilitation, according to detailed instructions from the surgeon.