What is Femoroacetabular Impingement (FAI)?
If you have been experiencing hip pain with hip flexion (moving your knee upwards), external rotation, or internal rotation, you would have probably experienced some stiffness or even locking in your hip. Very often, patients will describe their hip as being misaligned or that something is out-of-place.
This is how the diagnostic label femoroacetabular impingement syndrome came about.
For most parts, it was assumed that in the condition the bones of your hip joint are pinching tissues causing movement issues or pain. However, the latest research is starting to find that FAI findings are common even in asymptomatic individuals.
As many as up to 31% of individuals without hip pain or symptoms or whatsoever would show some form of “abnormality” that is consistent with FAI on their MRIs or CT scans.
This challenges our understanding of how an “impinged” hip may hurt and the treatment options that are sensible for hip pain patients.
What causes femoral acetabular impingement?
It is not clear what exactly causes FAI, or that why a third of individuals without any symptoms have FAI.
In that sense if you were to have hip pain and your MRI later shows that you have FAI, that alone is not enough for us to conclude that your hip pain is coming from the FAI.
To understand FAI better, you would have to understand your hip joint.
The hip joint, more accurately the acetabulofemoral joint, is made up of four bones. The femur (thigh bone) is the bone that joints into the cup-shape acetabulum, which is formed by the ilium, pubis, and ischium (three pelvic bones).
Because of the cup shape of the acetabulum and the ball shape of the femoral head (of the thigh bone), this joint is often referred to as a ball-and-socket joint.
The femur doesn’t join directly to the acetabulum per se. There is an articular cartilage that called the labrum that on the pelvic surface that holds the head of the femur bone in place.
You can imagine that damage to the labrum (e.g. labral tears) can result in abnormal contact between the bones. Sometimes the labrum is completely perfect but an abnormally shaped femoral head can cause changes to the hip joint. This is how we think impingement occurs.
There are two major classes of hip impingements. The cam impingement and the pincer impingement. In cam impingement, the head of the thigh bone is not perfectly round that that changes how it is able to move within the acetabular surface of the hip joint. As for pincer deformity, it results from the excess bone from the pelvic surface covering too much of the femur bone to allow normal movement.
It is possible for a patient to have both cam and pincer deformities.
What does research say about hip surgery?
The latest study on hip surgery (published Nov 2020) with 650 participants found that surgery for femoroacetabular impingement syndrome was no more effective than conservative treatment.
According to the authors, conservative treatment and surgery can both equally improve disability for femoroacetabular impingement syndrome patients.
This comes as a surprise as arthroscopic hip surgery is gaining popularity over the more less risky exercise-based treatments or activity modification approach to managing hip pain.
The biggest reason to support orthopaedic surgery intervention as the better treatment is that surgery can correct for anatomy changes in the hip that may be contributing to a person’s symptom experience. However, research has consistently shown that pain is more complex than that.
The latest studies have shown that MRI findings such as disc herniations or even knee osteoarthritis correlate poorly with an person’s pain experience. Furthermore, our current understanding of pain science has expanded to accept that non-physical factors (e.g. contextual factors) can contribute as much as physical factors to a person’s pain experience.
In that sense, as much as surgery can “correct” for hip impingement, it may not yield a superior outcome. Because the perceived impingement may not be the sole reason why a patient experiences hip pain!
With all of this information in mind, it doesn’t make sense to choose surgery first.
While it is indeed unfair to say conservative treatments yield better outcomes than surgery (according to this paper, it does not), it is reasonable to consider surgery as a higher risk treatment option.
Conservative treatments such as therapeutic exercises, strength and conditioning, physical therapy, motor control exercises help. These interventions have been reported to produce comparable results to surgery with significantly less risks and should be considered first-line treatment option for clients with hip pain.
If you have been diagnosed with hip pain that is not improving, book in an appointment with us to learn more about how we can help.