FAI
The hip is a ball-and-socket joint, and the largest weight bearing joint in the body. It is the bridge between the legs and the upper body and trunk. It supports the weight of the head and upper body and maintains posture and balance. The hip joint facilitates a diverse range of movements, from running and jumping to sitting and twisting.
The upper end of the thigh bone (femur) is the ball that fits into the socket (the acetabulum) in the pelvis. The acetabulum is lined with cartilage that allows the joint to glide easily and offers a wide range of motion. A strong ring of cartilage on the acetabulum called the labrum deepens the socket, acts as a shock absorber and helps to stabilize the hip joint. The inherently strong hip joint is fortified by strong ligaments and muscles that form the hip joint capsule to stabilize the joint.
Femoroacetabular impingement Syndrome, often abbreviated as FAIS (or FAI), is a structural problem caused by bony abnormalities that alter normal biomechanics between the ball and the socket. Premature contact between the femoral head/neck junction and the acetabulum can cause pinching/pressure of the cartilage and the labrum. FAI can cause pain, labral and cartilage tears, joint damage and accelerate joint degeneration over time.
In the long run, natural history studies have shown that FAI can lead to hip joint degeneration and osteoarthritis. Osteoarthritis is a degenerative joint condition characterized by the breakdown of joint cartilage and the underlying bone. In the context of the hip, this can result in pain, stiffness, and decreased function of the joint.
The two main causes of early hip osteoarthritis are FAI and hip dysplasia. Hip dysplasia is characterized by an ‘shallow’ acetabular articular surface, with suboptimal coverage of the femoral head. This leads to the early degenerative changes in the joint, labral pathology, and occasional micro-instability.
Genetic and developmental factors likely contribute to the development of bone abnormalities (cam or pincer lesions, see below) in the setting of FAIS. It is postulated that intense physical activity during the teenage years (i.e. during time of growth plate closure), especially from sports like soccer, ballet or ice hockey, can lead to the development of cam lesions in an attempt to stabilize the growth plate. Over time these morphological changes can lead to injury to the labrum and cartilage as described above.
- Cam Impingement: This occurs when the head of the thigh bone is aspherical, leading to abnormal contact with the acetabulum. In this type, the initial damage is to the labrum.
- Pincer Impingement: This occurs when the acetabulum has a focal prominence (i.e. focal retroversion) or global protrusion which lead to the abrasion of the acetabular cartilage and damage to the cartilage on the head of the femur (the ball).
- Mixed Impingement: A combination of both cam and pincer types is the most common and affects more than 80% of patients with FAI.
- Intermittent deep groin pain often aggravated by prolonged sitting, bending, or athletic activities. Pain may be sharp and stabbing or a dull ache.
- Instability and decreased range of motion, and stiffness or restriction, especially in hip flexion and rotation.
- Some patients may experience a clicking, popping, or locking sensation in the hip during certain movements.
- Pain in the outside of the hip sometimes felt in the buttock or thigh area.
- Limping may develop in more advanced cases or after prolonged activity.
- Discomfort may increase after periods of inactivity or immediately upon standing.
The first step is gathering a detailed history of the patient’s symptoms. This will include the nature, duration, and location of pain, as well as any activities or movements that exacerbate or relieve the pain.
The Hyper Regen Sports Medicine healthcare professional will assess the hip’s range of motion, strength, and stability using specific tests. They will order imaging studies including X-rays to view hip anatomy, assess for the presence of arthritis and measure important angles to understand your unique hip anatomy. A high resolution 3T MRI will also be arranged to visualize the soft tissues including the labrum and articular cartilage.
When FAI is diagnosed, a comprehensive treatment plan will be formulated. Treatment options include core strengthening (www.hipfit10.com), use of intra-articular injections for pain control and functional improvement and in the setting of failed non-operative care, hip arthroscopy may be considered.
Schedule a hip consultation
If you are experiencing hip pain and/or have been diagnosed with FAI, contact HyperRegen Sports Medicine to schedule a consultation to learn more.
At a Glance
Dr. Jas Chahal
- Head of Orthopaedic Surgery, Women’s College Hospital
- Team Physician Toronto FC and University of Toronto Varsity Blues
- Associate Professor, University of Toronto Orthopaedic Sports Medicine Program
- Has more than 100 peer-reviewed publications
- Learn more
