The diagnoses of hip injuries have arisen over the past decade. This increase is likely from the increase in understanding and diagnosis of hip impingements. Several hypotheses exist on the potential rise, but the most accepted is the greater understanding and diagnoses of hip impingement.

The American Academy of Orthopaedic Surgeons describes the following types of hip impingement (FAI).

In FAI, bone spurs develop around the femoral head and/or along the acetabulum (the area in the pelvis where the head of the femur lies). The bone overgrowth causes the hip bones to hit against each other, rather than to move smoothly. Over time, this can result in the tearing of the labrum and breakdown of articular cartilage (osteoarthritis) [also read about differences in hip tendon variation].

Types of Hip Impingement (FAI) Pelvic_girdle_illustration.svg

There are three types of FAI: pincer, cam, and combined impingement.

Pincer: This type of impingement occurs because extra bone extends out over the normal rim of the acetabulum. The labrum can be crushed under the prominent rim of the acetabulum.

Cam: In cam impingement the femoral head is not round and cannot rotate smoothly inside the acetabulum. A bump forms on the edge of the femoral head that grinds the cartilage inside the acetabulum.

Combined: Combined impingement just means that both the pincer and cam types are present.

Cam Hip Impingement

Cam femoroacetabular impingement (FAI) occurs when the head of the femur altering the movement in the joint. Specifically, a less spherical femoral head alters the contact area within the joint (at the acetabulum).

However, not everyone with a cam morphology exhibits pain or pathology.  Hip-2BPain2

Several studies have evaluated hip and pelvis kinematics during gait in persons with cam FAI. The results of these studies are varied and have reported that persons with cam FAI exhibit decreased motion in all planes.

Rylander et al. (2013) reported that individuals with cam FAI exhibited lower hip motion and hip internal rotation strength while climbing stairs.

Lamontagne et al. (2009) found less squat depth in people with a FAI impingement.

Kumar et al. (2014) reported altered movement patterns during a deep squat compared to controls.

Bagwell et al. (2015) showed  the cam FAI group had diminished squat depth, decreased hip strength, and more low back arching during flexion.The cam FAI group also exhibited decreased mean hip extensor moments compared to the control group.

However, Lamontagne et al. (2009) and Kumar et al. (2014) found no difference in peak hip internal rotation during deep squatting in persons with cam FAI compared to control subjects.

Cam Hip Impingement Treatment

The main treatment of a cam hip impingement is first to resolve pain. This is typically accomplished by reducing joint stress, which we find great success with manual therapy. Once pain is resolved, strengthening and retraining the muscles occurs. These areas also reduce stress at the joint and prevent further insult at the joint.

Here are some of our common therapeutic exercises in physical therapy for the treatment of cam hip impingement:


  1. Kumar, D., Dillon, A., Nardo, L., Link, T.M., Majumdar, S., Souza, R.B., 2014. Differences in the association of hip cartilage lesions and cam-type femoroacetabular impingement with movement patterns: a preliminary study. PM R 6, 681–689.
  2. Lamontagne, M., Kennedy, M.J., Beaule, P.E., 2009. The effect of cam FAI on hip and pelvic motion during maximum squat. Clin. Orthop. Relat. Res. 467, 645–650. Lodhia, P., Slobogean, G.P., Noonan, V.K., Gilbart, M.K., 2011. Patient-reported
  3. Rylander, J., Shu, B., Favre, J., Safran, M., Andriacchi, T., 2013. Functional testing provides unique insights into the pathomechanics of femoroacetabular impingement and an objective basis for evaluating treatment outcome. J. Orthop. Res. 31, 1461–1468.
  4. Bagwell JJ, Snibbe J, Gerhardt M, Powers CM. Hip kinematics and kinetics in persons with and without cam femoroacetabular impingement during a deep squat task. Clin Biomech (Bristol, Avon). 2015 Sep 25. pii: S0268-0033(15)00257-0. doi: 10.1016/j.clinbiomech.2015.09.016. [Epub ahead of print]

Dr. John Mullen


Dr. John Mullen, DPT, CSCS is a World renowned expert and speaker in sports training and rehabilitation. He received his Doctorate in Physical Therapy at USC, as well as the Josette Antonelli Division Service Scholarship, Order of the Golden Cane, and the Order of Areté. At USC, he also performed research on swimming biomechanics and lung adaptations in swimming training. Dr. John has worked with multiple professional and Olympic athletes, helping them earn Olympic medals. His dedication to research and individualization spurred him to open COR in 2011. Since 2011, Dr. John has been featured in Stack Magazine, Swimming World Magazine, Swimmer Magazine, USA Swimming, USA Triathlon, Swimming Science, and many more.  Before his Doctoral program, Dr. John swam on an athletic scholarship at Purdue University. At Purdue, Dr. John was an Academic Honorable Mention All-American and was awarded the Red Mackey Award and R. O. Papenguh Award. He also won the Purdue Undergraduate business plan and elevator pitch competition, as well as 1st prize with the Indiana Soy Bean Alliance. Dr. John was born in Centerville, Ohio and was a 24-time high school All-American Swimmer. Dr. John is still a swimmer and holds a Masters swimming World and Pacific Swimming Record.

Schedule with Dr. John