FAQ: Hip Impingement (FAI – Femoroacetabular impingement)

What is femoroacetabular impingement or hip impingement? This presentation is a result of bone overgrowth within the hip joint itself (refer to pictures below), causing reduced range of motion and potential hip cartilage damage. There are 3 types: CAM, pincer, or mixed. A CAM presentation is when the femoral head (the ball in the socket) has an increased growth. The pincer presentation is when the acetabulum (the socket for the ball) has an overgrowth. Symptoms often present acutely after performing movements/exercise, where damage has occurred within the hip joint because of this bone overgrowth. Movements such as a squat can causing a pinching type pain at the front of the hip. The bony overgrowth that causes this presentation occurs over a long period of time (months-years), it is not produced by an acute injury.

Source: https://orthoinfo.aaos.org/en/diseases–conditions/femoroacetabular-impingement/

Where will I feel pain? Pain for this presentation is often all around the hip – patients often describe discomfort inside the hip joint. The most common site of pain tends to be felt through the front of the hip. A classic sign is when they create a ‘C’ with their hand and cup the outside of their hip to describe pain front, back, and side of the hip (see picture). However, it can present as pain on the outside or back of the hip/pelvis, the low back or anterior hip, as well as the inside of the groin. Therefore, it can be a tricky for the layperson to identify the source of the problem without adequate testing from a clinician.  

Source: https://www.physiotutors.com/conditions/femoroacetabular-impingement/  

Clients often report a ‘pinching’ pain in their hip when they reach the end of their available range of motion within their hip. However, they often report a diffuse aching when sitting in comfortable positions if they have damaged the cartilage in the hip joint.  

What movements will I struggle to perform if I have injured this tissue/region? Positions of deep hip flexion (when you bring your knee towards your chest) – such as in low squat positions (think of sitting down/getting up out of a low chair) and adduction positions (when you bring your leg across your midline towards the other side) are provocative for this presentation. The combination of both movements often causes significant discomfort and the pinching pain referred to earlier.  

Will I feel pain in any other regions of my body? Yes, this is likely with this presentation. Due to the central location of the hip joints, and the involvement of both the femur (thigh bone) and pelvis – this can produce radiating/aching pain to many locations around the hip/pelvis. The most common locations are the low back and all sides of the hip.  

How does it happen? Wolff’s law states that bone responds to mechanical loading, and the body will align fibres within the bone based on the demands placed on it for loading. This principle can be further expanded to explaining that the bones within the hip joint will respond to high loads placed upon them by growing more bone in the hip joint. However, with increased bone loading on the femur or the pelvis, this limits the available range of motion within the hip and can cause significant pain. Furthermore, some people are genetically predisposed to this condition, and there is little they can do to prevent this presentation. A person’s genetics or their development as an infant can impact how someones hip joint is formed.

What things should I try initially once I’ve hurt myself? Soft tissue release around the hip and low back area can significantly improve symptoms of this presentation. We suggest some foam rolling or use of a trigger ball – if you are unfamiliar with how to do this effectively, then please get in touch with us and we will be happy to show you the techniques to help.  

What things should I try to avoid in the initial stages of aggravation? As discussed earlier, deep squatting positions and adduction positions are recommended to avoid flaring your symptoms in the short- to medium-term.  

What type of exercises or movements do I need to learn/control/be stronger at to rehab the hip? Isolated control of your hip and trunk muscles are the first-line treatment for this presentation along with soft-tissue release. We recommend a concerted effort to complete a 12-week rehabilitation period with strengthening and mobility exercises to elicit change to function and/or symptoms. However, if this period does not achieve the desired results, surgical opinion is warranted to remove the bone-block. It is important to note that the evidence is not definitive that surgery will solve this issue – some clients regrow the bone that is removed to create space for range of motion. Therefore, consultation with an experienced clinician is recommended for this step.   

What other considerations contribute to the injury? General lower limb control/strength (i.e. leg strength) and trunk control/strength can significantly mitigate how much load the hip must endure when completing tasks. Therefore, targeting these body parts are very important considerations for a successful rehabilitation program.  

What treatments can help relieve some pain or fast track my rehabilitation? Osteopathy and Physiotherapy can significantly help to reduce the acute symptoms of discomfort in the hip/surrounding tissues. Targeted exercises from your clinician will fast-track your rehabilitation.  

What are the expected timeframes of rehabilitation? This presentation is less likely to be acute, therefore, rehabilitation timelines are expected to be longer than other injuries. A minimum of 12 weeks is expected for rehabilitation; however, exact timeframes depend on concomitant injuries and adherence to a rehabilitation program.