Cam Lesions: Symptoms, Causes, and When to Seek Medical Attention

What are the symptoms of a cam lesion?

A cam lesion primarily manifests as deep, aching pain in the groin, often exacerbated by hip flexion, adduction, and internal rotation, alongside stiffness and a reduced range of motion in the hip joint, particularly during activities like squatting or prolonged sitting.

Understanding Cam Lesions

A cam lesion is an anatomical abnormality of the femoral head and neck, where there is an excessive amount of bone, creating a non-spherical shape. This bony prominence is typically located at the junction of the femoral head and neck. In the context of hip mechanics, this morphological deviation leads to a condition known as femoroacetabular impingement (FAI).

What is a Cam Lesion? A cam lesion specifically describes an abnormal "bump" on the femoral head-neck junction. When the hip is flexed and internally rotated, this bump can abnormally contact the rim of the acetabulum (the hip socket), leading to repetitive microtrauma.

Femoroacetabular Impingement (FAI) FAI is a condition where the bones of the hip joint abnormally contact each other, leading to damage to the articular cartilage and/or the labrum (a rim of cartilage that deepens the hip socket). Cam lesions are one of the primary types of FAI, often occurring in active young adults and athletes due to the high forces and ranges of motion placed on the hip.

Impact on Hip Joint Mechanics The abnormal contact caused by a cam lesion can pinch and damage the articular cartilage and the labrum, leading to inflammation, pain, and over time, potentially accelerating the development of hip osteoarthritis. Understanding these mechanics is crucial to appreciating the symptoms experienced.

Primary Symptoms of a Cam Lesion

The symptoms of a cam lesion are primarily mechanical, arising from the impingement of the abnormal femoral head against the acetabulum. They can vary in intensity and frequency, often progressing over time.

• Deep, Aching Groin Pain: This is the most common and classic symptom.
  • Location: Typically felt deep in the anterior (front) groin area. It can sometimes radiate laterally towards the greater trochanter or posteriorly towards the buttock.
  • Aggravating Factors: Pain is often worsened by activities involving hip flexion, such as sitting for long periods, driving, squatting, lunging, or climbing stairs.
• Pain with Specific Movements: Certain movements reliably reproduce the impingement and associated pain.
  • Hip Flexion: Bringing the knee towards the chest.
  • Hip Adduction: Moving the leg across the midline of the body.
  • Internal Rotation: Rotating the foot inward when the hip is flexed (often combined with flexion and adduction, as in the FADIR test).
  • External Rotation: Less common, but can occur in some cases.
• Stiffness and Reduced Range of Motion: Individuals often experience a feeling of stiffness in the hip, particularly after periods of inactivity or in the morning.
  • Limited Internal Rotation: This is a hallmark finding, as the cam lesion physically blocks the movement.
  • Limited Hip Flexion: Difficulty bringing the knee fully to the chest without pain or a hard end-feel.
• Clicking, Catching, or Locking Sensation: These are mechanical symptoms indicating that the damaged labrum or cartilage is getting pinched or caught within the joint.
  • Clicking: A distinct sound or sensation during movement.
  • Catching: A momentary hang-up or block in the joint's movement.
  • Locking: A more severe form of catching where the joint temporarily gets stuck.
• Pain Radiating to the Thigh or Buttock: While the primary pain is in the groin, some individuals may experience referred pain down the front or side of the thigh, or into the buttock area. This is less common than groin pain but can occur.

Aggravating Activities

Symptoms of a cam lesion are often activity-dependent, meaning they worsen with specific movements or positions that provoke impingement.

• Prolonged Sitting: Especially in low chairs or driving, where the hip is held in a flexed position.
• Deep Squatting or Lunging: Activities that demand significant hip flexion and internal rotation, particularly under load (e.g., weightlifting).
• Sports-Specific Movements:
  • Kicking: As seen in soccer or martial arts.
  • Pivoting/Cutting: Common in many field sports like basketball, football, or soccer.
  • Ice Skating or Hockey: Involving deep hip flexion and internal rotation.
  • Yoga or Pilates: Certain poses that push hip range of motion.
• Getting In/Out of a Car or Low Chair: Requires a combination of hip flexion and rotation.
• Ascending or Descending Stairs: Can exacerbate groin pain.

Progression of Symptoms

The onset of symptoms from a cam lesion is often insidious, meaning it develops gradually over time rather than suddenly after an acute injury.

• Intermittent Pain: Initially, pain may be intermittent, occurring only during specific, highly provocative activities.
• Constant Pain: As the condition progresses and more damage occurs to the labrum and cartilage, the pain can become more persistent, affecting daily activities even outside of exercise.
• Impact on Performance: Athletes may notice a decline in performance, an inability to perform certain movements, or pain that limits training.
• Potential for Osteoarthritis: If left untreated, the chronic impingement and resulting damage can lead to degenerative changes and early onset hip osteoarthritis.

Differentiating Cam Lesion Symptoms from Other Conditions

It's important to note that many hip and groin conditions can present with similar symptoms. Conditions such as labral tears (which often co-exist with cam lesions), adductor strains, iliopsoas tendinitis, sports hernias, or even lumbar spine issues can mimic FAI symptoms. Therefore, a thorough differential diagnosis by a healthcare professional is crucial. The distinct pattern of pain during specific provocative movements, combined with imaging findings, helps distinguish a cam lesion from other pathologies.

When to Seek Medical Attention

If you experience persistent hip or groin pain, especially if it is deep and aching, worsens with hip flexion and rotation, or is accompanied by stiffness, clicking, or catching, it is advisable to seek medical evaluation. Early diagnosis and intervention can help manage symptoms, prevent further joint damage, and improve long-term hip health.

Diagnostic Process

A healthcare professional, such as an orthopedic surgeon, sports medicine physician, or physical therapist, will conduct a comprehensive evaluation. This typically includes:

• Clinical Examination: Assessing hip range of motion, muscle strength, and performing specific provocative tests (e.g., FADIR test).
• Imaging Studies:
  • X-rays: To assess the bony morphology of the femoral head and acetabulum (e.g., alpha angle for cam lesion assessment).
  • MRI (Magnetic Resonance Imaging): To visualize soft tissues like the labrum and articular cartilage for damage.
  • MR Arthrography: An MRI with contrast injected into the joint, which can provide a clearer view of labral tears.
• Diagnostic Injection: Sometimes, a local anesthetic injection into the hip joint is used to confirm the hip as the source of pain.

Conclusion and Importance of Early Intervention

Recognizing the symptoms of a cam lesion is the first step toward effective management. While the primary symptom is deep groin pain exacerbated by specific movements, the insidious onset and potential for long-term joint damage underscore the importance of early diagnosis. For fitness enthusiasts, personal trainers, and student kinesiologists, understanding these symptoms allows for more informed training decisions, appropriate modifications, and timely referrals to medical professionals, ultimately preserving hip function and promoting lifelong physical activity.