(AKA: Femoral Acetabular Impingement, Femoro-Acetabular Impingement)
What is it?
Femoroacetabular impingement or FAI is a condition of too much friction in the hip joint. Basically, the femoral head (ball) and acetabulum (socket) rub abnormally creating damage to the hip joint. The damage can occur to the articular cartilage of the femoral head, acetabulum or the labral cartilage. A labral tear is very common in FAI. The labrum is ring of cartilage that follows the outside rim of the hip joint. There is a labrum in the shoulder joint as well. The labrum acts like a gasket on the outside of the socket to hold the ball of the femur in place.
Hip problems in general often involve labral tears however, these tears are often secondary to abnormal hip biomechanics such as the labrum getting caught by friction between the bone of the ball (femoral head) and the bone of the socket (acetabulum) the condition of FAI.
FAI generally occurs as two forms: Cam and Pincer. Cam comes from the Dutch word meaning “cog,” which describes the femoral head and neck relationship as aspherical or not perfectly round. This loss of roundness contributes to abnormal contact between the head and socket. The Pincer form comes from the French word meaning “to pinch which describes where the socket or acetabulum covers too much of the ball or femoral head. This excessive coverage typically appears along the anterior-top rim of the acetabulum and results in the labral cartilage being pinched between the rim of the socket at the anterior femoral head-neck junction. Most of the time, the Cam and Pincer forms exist together- i.e., mixed impingement. This is what I personally experienced.
FAI is common in high level athletes, but also occurs in active individuals.
How is it diagnosed?
Excessive hip flexion with external rotation or excessive hip flexion with internal rotation places excessive compression and torsional forces on the hip, especially the labrum. As a competitive cyclist I’m used to experiencing joint pain and muscle soreness. Prior to my diagnosis I had recently increased my involvement with racing the velodrome. I had borrowed a track bike that was too small for me which put me in a hyper-flexed position. However, the smaller frame provided greater control on the track. Track bikes have a fixed gear so the cyclist can never stop pedaling. The races are much shorter and faster, so the cyclist is almost always in the drops or race position. Because there are no gears there is an incredible amount of torque needed to accelerate the bike. The pain I felt in my hips seemed as if it were tight hip flexors. I figured I just needed more rest and more stretching. I was already strengthening the antagonists to the hip flexors but, neither the strengthening or the stretching was helping. It finally got to the point where I couldn’t ride at all.
Many people can be diagnosed with a good health history, physical exam, and plain x-ray films. Some believe that significant athletic activity before skeletal maturity increases the risk of FAI, but no one truly knows. There is usually a common complaint of hip pain (front, side, or back) and loss of hip motion. Plain x-ray films are used to determine the shape of the ball and socket as well as assess the amount of joint space in the hip. Less joint space is generally associated with more arthritis. In my case, I required an MRI of the hip. However, I had the first MRI without contrast. This was a mistake because it didn’t show us enough. I had to go back and redo the MRI with contrast. This meant they had to numb my hips and then inject them with dye before the MRI was taken. The MRI with contrast is most helpful in eliminating certain causes of non FAI hip pain including avascular necrosis (dead bone) and tumors. A normal MRI does not preclude cartilage injury, labral tears, or FAI. After my second MRI with contrast, we discovered I had torn the labrums in both hips.
What other diagnoses might be confused with FAI?
Hip Dysplasia (Adult Form)
Lumbar Spine Pain (Low Back Pain)
Lumbar Radiculopathy (Low Back Pinched Nerve, Low Back Facet Disease)
Sacroilitis (SI Pain/Dysfunction, back of pelvis)
Trochanteric Bursitis (Outside/Lateral Hip Pain)
Piriformis Syndrome (Back of Hip Pain)
Psychosomatic Pain Disorder (Stress Related Illness)
Iliopsoas Tendinitis/Tendonitis/Tendinosis (Hip Flexor Inflammation)
Groin Pull (Adductor Strain)
Sports Hernia (abdominal muscle strain)
Iliac Apophysitis (Front of Pelvis Pain)
Quadriceps Hernia/Strain (Thigh Muscle Pull)
Deep Gluteal Syndrome (DGS)
Chronic Pain Syndromes
With what activities is FAI associated?
Some common activities:
Martial Arts and Mixed Martial Arts
Deep squatting activities such as power lifting
Rowing Sports (Kayaking, Sculling/Rowing)
Car riding, flying in an airplane (deep seated position, bucket seat position)
Why does it occur?
No one knows if FAI is a condition that begins at birth or develops during periods of growth. It is likely a combination of one’s genetics and environment or activities.
How long can I wait before seeking treatment?
Typically, FAI that produces symptoms should be evaluated for surgical treatment. A delay in FAI treatment may compromise the cartilage of the hip.
Can I be treated with an injection of medicine or good physical therapy?
Generally, FAI is a chronic condition that does not typically respond to hip injections or physical therapy over the long term. I tried Platelet Rich Plasma (PRP) injections and it didn’t help. That being said, a core strengthening program instead of hip stretching may be beneficial. In fact, stretching or yoga may make the symptoms worse.
Do I have arthritis if I have FAI?
Both plain film x-rays and MRI scans are an incomplete view of the cartilage inside the hip joint. It is possible and common to have good joint space on plain x-ray films and no signs of arthritis on the MRI and still have significant loss of cartilage within the hip.
Can my other hip be involved as well?
Yes, it is possible for both hips to have FAI.
What are my treatment options?
Non-operative management of FAI is possible; however, it involves a change in lifestyle from active to less active and a commitment to maintaining hip strength. Non-operative management will not change any underlying abnormal hip biomechanics of FAI and may contribute to further hip degeneration.
Operative management of FAI can be addressed via hip arthroscopy or open surgery. A hip arthroscopy involving labral debridement (no repair) and no bony decompression usually takes less than one hour. A hip arthroscopy involving labral/cartilage repair and FAI decompression may take between two and four hours, depending on the amount of work performed.
The open surgical hip dislocation approach can typically be done in a few hours. The open approach is not generally recommended in older patients, in patients with significant hip degeneration, or in patients with significant athletic/activity demands.
Recovery time from most arthroscopic FAI surgical procedures is about three to four months to full, unrestricted activity. Your postoperative activity level will depend on your surgeon’s recommendation, the type of surgery performed, and the condition of the hip joint at the time of surgery. FAI open surgery may involve a significantly longer recovery.
What are the main risks of FAI treatment?
Complications from FAI hip surgery are uncommon but include the following:
DVT (blood clot)
Hip Instability & Dislocation
Femoral neck fracture
AVN of the femoral head (dead bone)
Heterotopic ossification (abnormal bone formation in soft tissues)
Nerve injury (Sciatic, LFCN, Pudendal, Peroneal)
Nonunion (open surgical dislocation only)
How do you rehabilate FAI?
In the end, I had both of my hips successfully operated arthroscopically. Now I had to rehab them.
Prior to surgery I visited five orthopedic surgeons, two doctors of physical therapy and spoke to a sixth orthopedic surgeon on the phone. All six surgeons recommended to ride the stationary bike within 48 hours of the surgery. This will improve the blood flow and maintain some mobility.
It’s important that the hip joints stay in neutral. After surgery, you’re given a hip fixator made of foam that velcros around your feet and hips so the hips won’t externally rotate at night. In order to repair the labrums the surgeon places an anchor in the pelvis so they can sew the lambrum. They don’t want you to pull that out by externally rotating at night.
Crutches are recommend for two – three weeks. For both surgeries I was on crutches for three days. I was able to weight-bear on the fourth day for each surgery so I started to walk slowly. Once the wounds had healed I went straight to the pool. I’ve had eight orthopedic surgeries and always successfully began my rehab in the pool. The water compresses the joint, you way weigh less and the resistance is accommodating.
Focus on range of motion. Stationary cycling and light gentle movements in the water are the best way I’ve found to rehabilitate orthopedic injuries. In the pool, do hip flexion, extension, abduction, adduction, internal rotation, external rotation, circumduction and walk. After about 10 days of stationary cycling and aquatics, you’ll be ready to move to a land based program. Hip flexion will be painful at the start. Try to passively stretch the hip flexors. It won’t be easy, but you must try. Concentrate on strengthening the hip extensors such as the glutes and hamstrings. The glute medius and minimus will be important to target as well; adduction and abduction can be done conservatively. Squats or lunges will be very difficult and will most likely cause pain. Start with partial range of motion as pain permits. As the range of motion improves and the pain subsides, continue to strengthen all the muscles surrounding the hips but be ever vigilant for tight hip flexors and internal rotators. Depending on where the surgeon made his incisions, the tissue surrounding those incisions will shorten and become tight.
Rehabilitating is different than strengthening. It must be gradual and not that strenuous. It’s more about fluidity of motion. Patience is a virtue. Don’t worry, the body revives itself and you will come back. Sleep and good nutrition is a must. Your body will need more of both.