The hip joint, also known as a “ball and socket” joint is located where the
femur (the thigh bone) meets the pelvic bone. The upper segment (“head”) of
the femur is a round “ball” that fits inside the acetabulum or the “socket” part
of the pelvic bone. The “ball” is normally held in the “socket” by very powerful
ligaments that form a complete capsule around the joint. Both the ball and
socket are covered with a thin layer of smooth cartilage.
This cartilage acts to cushion the joint, allowing the bones to move with very
little friction, allowing your hip to work properly. The depth of the acetabulum
(socket) is increased by a fibrocartilaginous rim called a labrum. The labrum
acts as a gasket to ensure the ball fits into the socket, further securing the hip
What is Femoral Acetabular Impingement (FAI)
• What is it?
• Femoral Acetabular Impingement (FAI) occurs when the head of the femur
does not have full range of motion within the socket.This abnormal contact,
with time, can cause injury to the fibro-cartilaginous labrum that lines the
socket. The injury to the labrum can then continue to progress and result in
degenerative joint disease that can result in arthritis.
• Who gets it?
• Impingement can present at any time between the teenage years and
middle age. Impingement usually occurs in young athletic patients and
presents with a slow onset of groin pain that may start after a minor trauma.
Signs and Symptoms
• During the initial phase, many patients first notice an intermittent pain in the
front of their hip or groin area.
• The pain may become worse with excessive demand on the hip from
physical activity or after prolonged sitting
• Walking up hill is found to be difficult
• The pain can also be a consistent dull ache with or without a catching and/or
sharp, popping sensation
• Pain can also be present along the side of the thigh and in the buttocks.
Types of Impingement
There are 2 distinct types of FAI based on the pattern of injury the labrum:
• CAM Impingement
• Pincer Impingement
Cam impingement occurs when an larger abnormally shaped femoral head is
jammed into the acetabulum during normal range of motion. This jamming
results in tearing of the labrum and/or pulling the labrum away from the rim.
The tear often occurs in the top-front part of the labrum and most commonly
occurs in young active Clients
Pincer impingement results from abnormal contact between the rim of the
acetabulum and the femoral neck. The abnormal contact is mostly the over
coverage of the femoral head.
How Is It Diagnosed?
• Physical examination of the hip by a trained doctor often reveals limitations
in range of motion.
• A manoeuvre test that looks for impingement is almost always positive.
• X-ray and magnetic resonance imaging (MRI) play an important role in
• X-ray can reveal an excess of bone on the femoral head or neck, and on
the acetabular rim.
• An MRI can reveal fraying or tears of the cartilage and labrum.
• A special MRI called an MRI arthrogram.
Treatment for hip impingement should begin with:
• Resting the affected hip
• Modifying your activities to avoid moving the joint in a way that causes pain
• Exercising as recommended by your doctor or physical therapist to
strengthen the muscles that support the hip
• Taking anti-inflammatory and pain medications
• If these treatments do not relieve pain, your doctor may recommend hip
Surgery For Femoral Acetabular Impingement
The type of surgery needed will depend on the problem causing hip
impingement and how much cartilage damage has occurred.
If the affected hip does not have too much cartilage damage, the surgeon
may use tools to reshape the ball and/or the outside edge of the socket that is
catching on the thigh bone. In a technique called microfracture, the surgeon
may also cut away the frayed cartilage that is causing pain or drill holes into
patches of bone where cartilage has worn away in order to stimulate cartilage
growth. Microfracture is being used less frequently.
Often, surgery for hip impingement can be performed arthroscopically. This
technique involves inserting a lighted scope and thin tools through small
incisions over your hip instead of making a large incision. Arthroscopy is
usually an outpatient surgery. This means you can go home the same day.