Hip Impingement

The hip joint is a ball-and-socket joint composed of the head (ball) of the femur (thigh bone) and the acetabulum (the socket). The joint allows smooth movement of the leg in multiple directions, supported by cartilage and a fibrous rim called the labrum, which helps stabilize the joint. In hip impingement, irregularities in the shape of the femoral head or the socket cause them to rub against each other during motion.
There are two primary types of hip impingement.
• Cam impingement occurs when the femoral head is not perfectly round, leading to jamming of the ball against the socket rim during motion.
• Pincer impingement happens when the acetabulum covers too much of the femoral head, causing the rim of the socket to pinch the labrum.
• Many individuals have a combination of both types, known as mixed impingement.
Over time, this abnormal contact can lead to labral tears, cartilage breakdown, and early osteoarthritis. Without intervention, the damage may progress, resulting in chronic pain and reduced hip function.

The hip joint is a ball-and-socket joint composed of the head (ball) of the femur (thigh bone) and the acetabulum (the socket). The joint allows smooth movement of the leg in multiple directions, supported by cartilage and a fibrous rim called the labrum, which helps stabilize the joint. In hip impingement, irregularities in the shape of the femoral head or the socket cause them to rub against each other during motion.

There are two primary types of hip impingement.

• Cam impingement occurs when the femoral head is not perfectly round, leading to jamming of the ball against the socket rim during motion.
• Pincer impingement happens when the acetabulum covers too much of the femoral head, causing the rim of the socket to pinch the labrum.
• Many individuals have a combination of both types, known as mixed impingement.

Over time, this abnormal contact can lead to labral tears, cartilage breakdown, and early osteoarthritis. Without intervention, the damage may progress, resulting in chronic pain and reduced hip function.

The symptoms of hip impingement often develop gradually and may worsen with activity. The most common symptom is pain in the front of the hip or groin, which can radiate to the outer hip or buttock. Some patients also experience a deep ache in the hip joint, especially after prolonged sitting, walking, or exercising.

Pain typically increases with activities that involve hip flexion or rotation, such as squatting, running, cycling, or climbing stairs. Many patients describe a catching, locking, or clicking sensation within the hip, suggesting damage to the labrum. Stiffness and a feeling of tightness in the hip joint are also common.

As the condition progresses, the range of motion becomes limited, and simple activities like bending forward or tying shoes may become uncomfortable. Over time, persistent irritation and inflammation can cause the pain to spread to the thigh or lower back, further limiting mobility and athletic performance.

Hip impingement typically arises from structural abnormalities of the hip joint that may develop during growth. In cam impingement, excessive bone growth around the femoral head results in a misshapen ball that cannot rotate smoothly within the socket. Pincer impingement, on the other hand, develops when the acetabulum (the socket) extends too far over the femoral head, often due to subtle differences in bone development.

Although some people are born with these variations, repetitive hip movements can exacerbate the condition. Athletes who participate in sports involving frequent hip flexion—such as soccer, hockey, football, dance, and martial arts—are at higher risk. Repetitive motion and high impact activities accelerate wear and tear on the joint surfaces, promoting cartilage damage and labral tears.

Other risk factors include a history of childhood hip conditions which can alter the shape of the hip joint. Genetics may also play a role, as certain individuals inherit structural variations that predispose them to impingement.
Age is another factor. While hip impingement is more common in young and middle-aged adults, early detection is crucial to prevent long-term joint damage. Inactive individuals with subtle hip abnormalities may remain asymptomatic until later in life when degenerative changes set in.

If left untreated, hip impingement can lead to progressive damage within the joint. The repeated contact between bone and cartilage can cause labral tears and cartilage delamination, eventually resulting in early-onset osteoarthritis. Once cartilage is lost, it cannot regenerate, leading to chronic stiffness, persistent pain, and reduced function.
Athletes with untreated impingement may notice a decline in performance due to restricted motion and discomfort during hip rotation. Prolonged inflammation can also contribute to compensatory movement patterns, placing stress on the lower back, knees, or opposite hip.

Over time, the condition may progress to the point where nonsurgical management is ineffective, and more invasive procedures, such as hip arthroscopy or joint replacement, become necessary. Early recognition and evaluation are key to preventing these complications.

Dr. Collon will review the patient’s medical history, activity level, and specific symptoms. A thorough physical examination focuses on hip range of motion, flexibility, and pain response during specific movements. The impingement test, in which the hip is flexed and rotated inward, often reproduces the pain associated with FAI and helps confirm clinical suspicion.

Imaging studies are essential to identify the structural cause of impingement and assess the extent of joint damage.

• X-rays of the hip and pelvis reveal abnormalities in bone shape, such as cam lesions or over-coverage of the socket.
• Magnetic resonance imaging (MRI) provides detailed visualization of soft tissues, including the cartilage and labrum, and can detect tears or inflammation that may not appear on X-rays.
• In some cases, an MRI arthrogram, which involves injecting contrast dye into the hip joint, offers enhanced clarity for diagnosing labral tears.
• Occasionally, CT scans are used to create three-dimensional reconstructions of the hip, allowing surgeons to precisely evaluate bony abnormalities before planning treatment.

Early and accurate diagnosis allows for targeted management strategies that can help preserve the hip joint, reduce pain, and prevent the progression to arthritis.

Hip impingement is a common source of hip and groin pain in young adults and athletes. Recognizing symptoms early can help patients seek timely evaluation from an orthopedic surgeon.