Femoroacetabular Impingement (FAI): Symptoms and Treatment Options

Femoroacetabular impingement (FAI) is a condition where the femoral head (the “ball” of the hip) and acetabulum (the “socket” of the pelvis) come into abnormal contact, leading to damage in the joint. This repetitive friction can cause pain, stiffness, and, if left untreated, long-term joint damage and arthritis. FAI is often found in active individuals and athletes who perform frequent hip movements but can affect anyone with certain hip structural abnormalities. Knowing the symptoms, causes, and treatment options for FAI can aid in early management and help prevent further complications.

What is Femoroacetabular Impingement (FAI)?

Femoroacetabular impingement occurs when the hip’s ball and socket do not fit together smoothly, causing abnormal contact and friction between the bones. Over time, this repeated contact leads to wear and tear on the cartilage and labrum, a ring of cartilage surrounding the hip socket. The labrum provides cushioning and stability for the hip joint, and when damaged, it can cause pain, limited range of motion, and eventual joint deterioration.

FAI is classified into three types based on the type of structural abnormality:

  1. Cam Impingement
    Cam impingement occurs when the femoral head is not perfectly round. This misshapen femoral head doesn’t move smoothly within the socket, creating friction against the acetabulum, which can damage the labrum and cartilage. Cam impingement is commonly seen in athletes, particularly in sports requiring hip rotation, such as soccer, basketball, and martial arts.
  2. Pincer Impingement
    Pincer impingement happens when the acetabulum (hip socket) has an excessive bony rim that extends over the femoral head. This causes the acetabulum to “pinch” the labrum during hip movements. Pincer impingement is more common in middle-aged women and can affect both hips simultaneously (bilateral FAI).
  3. Combined (Mixed) Impingement
    In combined or mixed FAI, both cam and pincer impingements are present, leading to even greater friction within the joint. This type of FAI is associated with accelerated joint damage due to the compounded friction, often requiring early treatment to prevent progression.

Each type of FAI puts the labrum and joint cartilage at risk. Damage to these tissues increases the likelihood of developing osteoarthritis in the hip, a condition that can cause chronic pain and disability.

Causes of Femoroacetabular Impingement

FAI typically develops from structural abnormalities within the hip joint. These abnormalities may be congenital or result from environmental factors. Common causes and risk factors include:

  1. Genetic and Developmental Factors
    Many people with FAI have a genetic predisposition, as certain hip shapes are inherited. Developmental factors in childhood can also play a role; for example, growth plate abnormalities during adolescence may cause the femoral head to develop an irregular shape. Genetics and early hip development are often why some individuals are more likely to experience FAI.
  2. High-Impact Sports and Repetitive Hip Movements
    Participating in sports that involve repetitive hip flexion and rotation, such as gymnastics, hockey, football, and ballet, increases the risk of FAI. Repeated stress on the hip joint over time can promote bone overgrowth, particularly in the femoral head or acetabular rim, leading to cam or pincer impingement. This high-impact activity gradually leads to structural changes that can result in FAI, particularly in young, active individuals.
  3. Hip Injuries and Trauma
    Past hip injuries, including fractures, dislocations, or strains, can predispose individuals to FAI. When the hip joint sustains trauma, it may not heal perfectly, which can alter the alignment of the hip joint. This improper alignment or irregular bone growth can contribute to abnormal contact within the hip, leading to impingement.
  4. Excessive Physical Activity During Growth Phases
    Physical activity during growth spurts, especially in adolescence, can affect the shape of the hip joint. Sports or high-impact activities that involve repetitive hip movement can lead to abnormal bone growth patterns, particularly in the femoral head. This increased mechanical load during growth can result in structural abnormalities associated with FAI.
  5. Age and Lifestyle Factors
    Although FAI is commonly found in younger, active people, it can also develop in older adults. As people age, their bones may develop irregularities such as bone spurs, which can exacerbate FAI. Age-related cartilage changes also increase susceptibility to FAI as the joint surfaces become less smooth, making movement more frictional and uncomfortable.

Symptoms of Femoroacetabular Impingement

The symptoms of FAI can vary based on the type and severity of the impingement and are often gradual, increasing in intensity over time as joint damage progresses. Common symptoms include:

  • Hip or Groin Pain
    One of the primary symptoms of FAI is pain in the groin or hip area, particularly after extended periods of sitting, standing, or physical activity. The pain is often described as a deep, dull ache that may worsen with prolonged or repetitive movement. Pain may also radiate to the outer hip, buttocks, or thigh, depending on the extent of the joint irritation.
  • Sharp Pain with Certain Movements
    Many people with FAI experience a sharp or pinching pain during specific movements, especially those involving hip flexion (such as squatting or bending) or hip rotation. Actions like twisting, running, or jumping can intensify the discomfort, as these movements increase the contact between the femoral head and acetabulum.
  • Restricted Range of Motion
    Over time, FAI can lead to stiffness and limited flexibility in the hip joint. Individuals may find it difficult to perform actions like crossing their legs, bending down, or rotating their hips, impacting their daily activities and sports performance.
  • Clicking or Locking Sensation in the Hip
    Some people with FAI report a clicking, locking, or catching sensation in the hip joint, caused by damage to the labrum or other joint structures. This sensation is uncomfortable and may indicate that the joint surfaces or labrum are already affected.
  • Weakness and Instability
    FAI can cause weakness around the hip and thigh muscles as individuals avoid movements that trigger pain. This weakness, in turn, can lead to instability or difficulty with balance, as the surrounding muscles become deconditioned, further impacting mobility.
  • Pain After Sitting or Standing for Extended Periods
    FAI-related pain often intensifies after sitting or standing for prolonged periods, particularly if the hip is kept in a flexed position. This “start-up” pain is common in FAI and can be especially bothersome when standing up after being seated for a while.

Diagnosing Femoroacetabular Impingement

Diagnosing FAI involves a combination of physical examination, imaging tests, and patient history. The diagnostic process is essential to determine the type and severity of impingement and any associated joint damage.

  • Physical Examination
    During the physical examination, the doctor will test hip movement, flexibility, and range of motion by asking the patient to perform specific movements. The “impingement test,” where the hip is flexed, internally rotated, and adducted, is commonly used to reproduce symptoms. Restricted or painful movements can help confirm the diagnosis.
  • Patient History and Symptom Review
    A detailed medical history and review of symptoms allow the doctor to understand the patient’s activity level, history of hip injuries, and the types of movements that trigger pain. This helps in assessing the severity and progression of FAI and tailoring an appropriate treatment plan.
  • Imaging Tests
    • X-rays: X-rays provide an overview of the hip’s bone structure and can reveal irregularities, such as a flattened femoral head (cam impingement) or an overextended acetabular rim (pincer impingement). X-rays are also helpful in detecting the presence of bone spurs or other structural changes that contribute to FAI.
    • MRI Scans: MRI imaging allows for a detailed view of the hip’s soft tissues, such as the labrum and cartilage. This is particularly useful for identifying labral tears or cartilage damage caused by FAI, making it an essential tool for evaluating joint health and planning treatment.
    • CT Scans: CT scans provide a three-dimensional view of the hip joint, allowing for more precise assessment of bone structure. This can be particularly helpful for pre-surgical planning, especially in cases where the structural abnormalities are complex and require careful surgical intervention.

Treatment Options for Femoroacetabular Impingement

Treatment for FAI focuses on alleviating pain, improving hip mobility, and preventing joint damage. Options range from conservative treatments to surgical intervention, with the goal of maintaining joint function and preventing arthritis.

  1. Activity Modification and Rest
    Avoiding or modifying activities that exacerbate symptoms is crucial for managing FAI. This may include limiting high-impact sports or adjusting workout routines to reduce strain on the hip joint. Resting the hip, particularly during pain flare-ups, allows the joint time to recover and prevents further irritation.
  2. Physical Therapy and Exercise
    Physical therapy is a cornerstone of FAI treatment, focusing on strengthening and stretching the hip, core, and gluteal muscles. Strengthening these muscle groups enhances hip stability and reduces joint stress, while stretching improves flexibility and reduces stiffness. Physical therapy also teaches patients proper movement patterns to avoid aggravating the joint, making it an essential part of long-term FAI management.
  3. Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)
    NSAIDs, such as ibuprofen or naproxen, are commonly used to relieve pain and reduce inflammation. While NSAIDs can provide short-term relief, they are not recommended as a long-term solution due to potential side effects, such as stomach irritation.
  4. Corticosteroid Injections
    For individuals with persistent pain, corticosteroid injections may be used to reduce inflammation in the hip joint. These injections can provide temporary relief, allowing patients to participate more comfortably in physical therapy and other rehabilitation activities.
  5. Surgical Options
    Surgery is considered when conservative treatments fail to alleviate symptoms or if significant joint damage is detected. Surgical options for FAI include:

    • Arthroscopy: Hip arthroscopy is a minimally invasive procedure that uses small instruments to remove bone spurs, repair labral tears, or smooth out damaged cartilage. This surgery is often used for both cam and pincer impingements and typically has a shorter recovery period.
    • Osteoplasty: In cases of cam impingement, osteoplasty reshapes the femoral head to allow for smoother movement within the socket. This procedure is often done during arthroscopy and can significantly reduce abnormal friction.
    • Labral Repair or Reconstruction: For patients with labral tears, labral repair or reconstruction may be necessary to restore stability and reduce pain. This procedure often involves using arthroscopic techniques to repair the torn tissue.
    • Periacetabular Osteotomy (PAO): PAO is a more invasive surgery for severe pincer impingement. This procedure repositions the acetabulum to reduce excessive femoral head coverage, helping to alleviate pressure on the labrum and cartilage. PAO is generally recommended when extensive bone modification is needed, and recovery time is longer than arthroscopy.

Recovery and Long-Term Outlook for Femoroacetabular Impingement

The prognosis for FAI depends on how early it is diagnosed and the treatment approach. With timely intervention, many individuals can manage symptoms effectively and maintain active lifestyles.

  • Recovery Timeline
    Recovery time varies depending on the treatment chosen. Those who undergo physical therapy may see improvement within a few weeks to months. For surgical patients, recovery can take several months, with a gradual return to activities as the hip heals. Full recovery following surgery may take six to twelve months, depending on the procedure.
  • Preventing Recurrence
    Maintaining strength in the hip and core muscles and following a regular stretching routine can help prevent the recurrence of FAI symptoms. Athletes and active individuals are encouraged to work with a physical therapist to develop sport-specific exercises that protect the hip joint.
  • Long-Term Monitoring
    FAI increases the risk of hip arthritis, so long-term monitoring with a healthcare provider is recommended. Regular follow-ups allow early detection of any new issues and ensure continued joint health, particularly for individuals with a history of joint damage or surgery.

Femoroacetabular impingement (FAI) is a condition marked by abnormal contact between the hip’s ball and socket, resulting in pain, stiffness, and eventual joint deterioration if left untreated. Recognizing the symptoms and exploring treatment options are essential for effectively managing FAI. With a range of options available, from physical therapy and NSAIDs to surgical interventions, individuals with FAI can find relief and work toward preserving joint health. Early intervention and a structured treatment plan can help patients maintain hip function, alleviate symptoms, and prevent future complications.