What is hip impingement?
Hip impingement syndrome is otherwise known as Femoroacetabular impingement (FAI). It is an impingement of the cartilage or labrum of the acetabulum with the movement of the femoral head.
Normal anatomy of the Hip Joint:
In an anatomically healthy hip, femoral head fits (plugs into) the acetabular socket making it a ball and socket type of joint. Thus, this joint allows good freedom of movement. This becomes possible as the femoral head can move smoothly within the socket in different directions.
The femoral head, as well as acetabular socket, are protected by bones and cushioned by smooth cartilage and labrum around the joint line. These soft tissues protect the joint from any rubbing, grinding or any friction against each other during the movement.
What happens in FAI?
As the name suggests, hip impingement occurs when something is impinging in the socket while the femoral head is moving. It is usually due to the development of bone spurs (bone overgrowth) around the femoral head and or along the acetabulum. This extra bone growth prevents a smooth movement of the joint. This increases the chances of labrum tear and degenerative changes (like OA) in a hip, which leads to pain during the movement.
Types of Hip Impingement:
Depending on where and how the impingement occurs it is divided into three types.
- Pincer Impingement:
Here, the extra bone growth occurs around the rim of the acetabulum.
- Cam Impingement:
Here, the femoral head is bumpy and not a smooth round formation. Thus, the head can not rotate smoothly inside the acetabulum. This is generally, a developmental deformity or present since childhood. This bump grinds the cartilage inside the acetabulum producing symptoms during the movements.
- Combined Impingement:
As the name suggests, there is a presence of both pincer and cam impingement.
Symptoms of Hip impingement?
- Pain in the hip during the movement, especially hip flexion
- Stiffness and pain in the thigh as well as the groin area
- Long sitting, running, jumping increases the pain.
Why does hip impingement occur?
Hip impingement or FAI can occur in adolescence or early adulthood. Overuse of hips in sports is usually a trigger to produce the pain. Therefore, young athletes usually complain of pain in and around the hip joint after running, or jogging or performing other sports activities.
Since childhood, the bone is not formed normally and so FAI is present since childhood. Contradictory though, not every person with FAI becomes symptomatic. Additionally, everyone demonstrates symptoms related to FAI at a different age.
People who are involved in sports, athletic or other activities that put vigorous pressure on the hip, are more prone to develop the symptoms of FAI.
How to diagnose Hip Impingement?
If the symptoms persist, one needs to see the doctor who will determine the exact cause by performing specific tests on a hip that can reproduce the pain. A doctor may order imaging tests like X-ray, CT scan, and MRI to check the anatomy of the bones as well as the severity of the damage to the bones.
Hip impingement test is the gold standard test to identify hip impingement. A physician, orthopedic doctor or a physical therapist can perform the hip impingement test.
This test puts the hip in flexion, adduction and internal rotation to lock the femoral head into the acetabulum. If pain is reproduced by this movement, the rest is positive for hip impingement. A clinician usually puts a patient in the supine position (on the back) with knee 90degrees flexed (if the range is allowed) for the test.
Medical Management of FAI:
When a person has a hip pain which increases with the movement, it is the best idea to give the hip a rest for a day or two. Trying to find out how the pain started and what could have caused the pain is the first approach one should take. One should consider avoiding the specific activity that brought the pain for a few days.
Rest, over the counter pain medicines (like ibuprofen, naproxen) and heat to relax the muscles may help to relieve the symptoms.
Physical therapy is one of the best conservative approaches to save the joint, to improve muscle strength and to reduce the pain.
Surgical interventions are necessary when symptoms persist even after the conservative management or the joint is damaged severely.
How can physical therapy help?
Physical therapy focuses on improving muscle strength and muscle length around the hip as well as the pelvic area. This, in turn, helps to gain more control around the hip joint and also to reduce pain.
Stretching hip flexors, rotators as well as adductors help to reduce the pain and improve mobility of the hip joint. Below pictures demonstrate how to perform these stretches.
Hip flexion stretch:
Hip Adductor stretch:
Strengthening of the muscles around the hip joint, pelvis, as well as core strengthening, is crucial in FAI. Below are examples of a few exercises.
Thre are many modified bridging exercises that one can perform. Once a person is mastered in bridging exercises, one can modify it by lifting one leg and adding pelvic tilt to it. The figure below shows a bridging while lifting a leg.
SLR in the prone position:
Additionally, one can also perform pelvic tilt exercises. This can be tilting pelvic side to side and back and forth. While seated on a ball, a person can also make clockwise as well as anti-clockwise circles with pelvic. These exercises open the hip joint and improve mobility as well as reduce pain.
Hip isometrics are also very useful exercises that one can perform.
If FAI occurred in an athlete or a sports person, it is important to train them for that specific sport. Sports specific training or task-specific training along with agility training usually are recommended prior to returning to sports.
Here is a PDF version for the exercise that you can print out.
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