Hip Unit
What is Femoroacetabular Impingement (FAI)?
Also known as “femoroacetabular impingement” in Central European and Anglo-Saxon languages, this condition, discovered by Swiss and German orthopedic surgeons in the late 20th century, is currently recognized as the leading cause of hip osteoarthritis—essentially the wear and tear of this joint. Scientific journals have reported that it was the underlying cause of hip osteoarthritis in 60-70% of patients who required a total hip replacement.
This condition is characterized by an impact occurring during internal flexion-rotation movements (inward rotation) between the lower portion of the femoral head and the acetabular rim. This leads to a distinctive pain that patients often describe as radiating around the hip, more specifically towards the groin. Two distinct mechanisms can be identified, which may occur individually or simultaneously:
Pincer Effect
This involves the femoral head-neck interface impinging on the anterosuperior wall of the acetabulum while simultaneously causing a “counter-strike” on its posteroinferior wall. The acetabulum presents an overcoverage or is even retroverted (Figures A and B).Cam Effect
In this case, there is an asphericity in the femoral head-neck interface, resulting in a prominence that, during flexion, presses against and abrades the anterosuperior wall of the acetabulum (Figures C and D).
Femoroacetabular impingement is the most common cause of hip pain in athletes, according to a recent publication by Dr. Marc Philippon in the American Journal of Sports Medicine. However, it is not exclusively a condition of athletes. For instance, it can occur after prolonged sitting while driving, working at a desk, etc. A study by Dr. Michael Leunig in the Swiss population revealed that 15% of people have hip deformities predisposing them to femoroacetabular impingement. Whether they experience symptoms depends on many factors, but current knowledge tells us that:
- Symptomatic patients should be treated as early as possible, as spontaneous remission without correction does not occur.
- Deformities should not be treated preventatively in the absence of symptoms.
Certain hip shapes are more prone to femoroacetabular impingement. For example, a prominent femoral head may collide with the acetabulum during flexion, preventing the femur from moving further into the joint. This friction damages the cartilage over time. Patients often notice, even in adolescence or early adulthood, difficulty flexing and internally rotating the leg. Activities like extended walking, especially uphill, getting in and out of cars, or sports such as golf, running, skating, or kicking can cause fatigue, a sensation of a “loaded hip,” or even pain.
Treatment of Femoroacetabular Impingement (FAI)
Surgical techniques commonly referred to as “osteochondroplasties” or “osteoplasties” aim to restore the natural shape of the hip. For instance, they involve removing the “prominence” and “acetabular overcoverage” to restore full mobility and eliminate femoroacetabular impingement. One of the most globally recognized techniques, developed by our unit, is the Ribas Minimally Invasive Osteoplasty Approach (6–8 cm incision). This method is a less aggressive alternative to the Ganz Osteoplasty (20–30 cm incision). The Ribas technique combines minimally invasive surgery with arthroscopy and its instruments, enabling precise hip reshaping and significantly faster recovery compared to the Ganz method. The latter requires a trochanteric osteotomy and hip dislocation, which are unnecessary in the Ribas approach.
This minimally invasive technique has been in practice for over 15 years, with more than 700 patients treated. Its effectiveness in addressing femoroacetabular impingement has gained international recognition, and numerous surgeons worldwide now adopt this method.
A third, increasingly popular option is osteoplasty via a purely arthroscopic approach. This involves using a fiber optic visualization system and two to three arthroscopic portals, each measuring 10–14 mm. Recovery with this method is comparable to the Ribas osteoplasty. Our Arthroscopy Unit, featuring nationally and internationally recognized experts such as Dr. Carlomagno Cárdenas-Nylander, is among the most experienced in Europe in this technique.
However, not all deformities causing femoroacetabular impingement can be treated solely with arthroscopy. For this reason, the Hip Unit assesses each case based on the type of deformity and the stage of the condition to determine whether the Ribas minimally invasive approach (which also incorporates arthroscopy) or a purely arthroscopic technique is more suitable. Postoperative and functional recovery are similar in both cases.
