Understanding the 3 Types of Femoroacetabular Impingement

When ongoing hip pain is little more than a minor irritation, an over-the-counter pain reliever may be all you need to get through your day. But when the pain is debilitating, it can interfere with your ability to walk, sit in a chair, go up and down stairs, and sleep through the night.

Chronic hip pain is a common complaint among people of all ages, including adolescents and young adults. Although it can be caused by an overuse injury like tendonitis, most cases of persistent hip pain are related to a degenerative condition like osteoarthritis, or a structural disorder like femoroacetabular impingement (FAI) — otherwise known as hip impingement.

FAI occurs when the one or both bones that make up your hip joint develop abnormally, causing them to rub against each other during movement. While many people with the condition lead active, pain-free lives for years, some degree of hip discomfort is inevitable, especially when continuous friction begins to damage or degrade the joint.

If you’re troubled by unexplained hip pain and stiffness, here’s what you should know about the three types of FAI — and why early treatment is so important.

Hip joint anatomy basics

Your hip is a ball-and-socket joint, where the rounded femoral head of your thigh bone, or the “ball,” sits inside the acetabulum, or “socket” area of your pelvic bone. In a healthy hip joint, these two pieces fit together perfectly so the ball can move both smoothly and securely within the socket.

Both the ball and the socket are lined with articular cartilage, a thin layer of slippery tissue that helps protect your bones and facilitate easy movement. The labrum, a special type of cartilage that lines the rim of the socket, forms a tight, gasket-like seal around the ball to help make the joint more stable.    

Femoroacetabular impingement

FAI occurs when bone overgrowth, or bone spurs, develop along or around the ball and/or socket of your hip joint. This extra bone tissue causes improper contact between the bones that can increase friction within the joint or pinch the surrounding tissues.

On top of preventing fluid movement and complete range of motion, FAI can lead to painful labrum tears as well as osteoarthritis, or the gradual and progressive breakdown of articular cartilage.

There are three basic types of FAI:

Cam impingement

As the most common form of FAI, cam impingement occurs when a bone spur on the ball-shaped end of the femur head leaves it misshapen. When the femoral head isn’t perfectly round, it collides with the acetabulum and can’t move smoothly within the socket.

As is often the case with cam impingement, a bony protrusion forms along the edge of the femoral head that grinds away at the cartilage inside the socket during movement.  

Pincer impingement

Pincer impingement occurs when the acetabulum covers or encloses the femoral head more than it should. This so-called “over-coverage” of the femoral head usually develops along the front-top rim of the socket, causing the neck of the femur to bump into the socket whenever you flex your hip joint by bending forward at the hip or drawing your knee toward your chest.

Combined impingement

Combined FAI simply means that bony overgrowths affect both the ball and socket — or that both the cam and pincer types of impingement are present in the same joint.

Advantages of early treatment

If you’ve been experiencing ongoing pain or stiffness in your thigh, hip, or groin, if your hip hurts after you’ve been sitting for a long time, or if you find it difficult to flex your hip beyond a right angle, you may have some form of FAI.

Even if your hip pain isn’t too serious yet, early diagnosis and intervention is always to your advantage — left untreated, FAI usually leads to irreversible cartilage damage, osteoarthritis, and chronic hip pain.  

Although physical therapy and rest can help you keep FAI under control, conservative measures don’t address the underlying bone abnormality. And the only way to truly address a misshapen hip joint bone — especially when conservative measures no longer provide effective pain relief — is through minimally invasive arthroscopic surgery.

Arthroscopic surgery seeks to alleviate pain and put a stop to further hip joint injury by removing the problematic bone spur, repairing soft tissue injuries, and re-contouring the ball and socket as needed.

As one of the leading experts in hip arthroscopy in Houston, as well as across the United States, Dr. Harris specializes in performing“postless” arthroscopy, an advanced procedure that helps eliminate the risk of some of the most common complications associated with traditional arthroscopy.

If you’re ready to put an end to chronic hip pain, we can help. Call our Houston office today, or use the easy online scheduling tool to book an appointment with Dr. Harris any time.