Femoroacetabular Impingement

Lower Limb

Overview

Femoroacetabular impingement is a condition characterized by abnormal contact between the femoral head-neck junction or acetabular rim and the acetabular cartilage, leading to pain and potential labral pathology. It represents a primary cause of hip osteoarthritis and is commonly seen in active individuals. Early identification and management are crucial to prevent progression to degenerative joint disease.

Pathophysiology

FAI occurs due to anatomical abnormalities in hip morphology, primarily involving either a cam deformity (excessive bone at the femoral head-neck junction causing abnormal impingement during flexion and internal rotation) or a pincer deformity (over-coverage of the femoral head by the acetabulum). These morphological variants cause increased joint stress, repetitive micro-trauma to the labrum and chondral surfaces, and inflammatory changes. Over time, this leads to labral tears, cartilage damage, and progression toward osteoarthritis if left unmanaged.

Patient Education

Hip FAI often improves with activity modification, strengthening of hip stabilizers, and maintaining hip mobility to reduce compensatory stress on the joint.

Typical Presentation

Site

Anterior groin pain, anterior thigh pain, lateral hip; may refer to buttock or knee

Quality

Sharp, catching, clicking, or pinching sensation in the groin; described as tightness or stiffness

Intensity

Mild to moderate (3-7/10) that worsens with activity; often activity-dependent

Aggravating

Prolonged sitting, hip flexion with internal rotation, squatting, stairs, running, pivoting movements, certain sports positions

Relieving

Rest, hip extension, external rotation, avoiding provocative positions, anti-inflammatory medication

Associated

Hip stiffness, reduced internal rotation (particularly pathognomonic), click or clunk with hip flexion, limping gait, buttock or lateral hip pain, functional limitations in athletics

Orthopaedic Tests

FABER Test (Flexion-Abduction-External Rotation)

Procedure

Patient supine; examiner flexes, abducts, and externally rotates the hip, then applies gentle overpressure. Positive if pain is elicited in the groin or anterior hip.

Positive Finding

Anterior groin or hip pain at end-range, particularly in flexion >60°, abduction, and external rotation

Sensitivity / Specificity

0.73 / 0.83

Reiman et al., 2015, Journal of Sport Rehabilitation

Interpretation

Suggests femoroacetabular impingement or intra-articular pathology (labral tear, capsular irritation). High specificity supports FAI when positive.

Anterior Hip Impingement Test (90/90 Test)

Procedure

Patient supine with hip and knee flexed to 90°. Examiner applies slight adduction and internal rotation passively. Positive if anterior groin or hip pain is reproduced.

Positive Finding

Sharp anterior hip or groin pain with combined hip flexion, adduction, and internal rotation

Sensitivity / Specificity

0.67 / 0.86

Nötzli et al., 2002, Clinical Orthopaedics and Related Research

Interpretation

Strongly suggestive of cam or combined-type FAI; high specificity indicates strong likelihood of FAI when positive.

FADIR Test (Flexion-Adduction-Internal Rotation)

Procedure

Patient supine; hip flexed to 90°, adducted, and internally rotated. Apply gentle overpressure. Positive if anterior hip or groin pain occurs.

Positive Finding

Anterior hip or groin pain with passive hip flexion, adduction, and internal rotation

Sensitivity / Specificity

0.97 / 0.13

Hegedus et al., 2015, Journal of Hip Preservation Surgery

Interpretation

Highly sensitive but poorly specific; pain indicates joint involvement but is non-specific to FAI alone. Often paired with FABER to improve diagnostic accuracy.

Anterior Hip Apprehension Test

Procedure

Patient supine with hip and knee flexed to 90°. Examiner applies passive external rotation and abduction. Positive if patient reports apprehension of instability or pain.

Positive Finding

Apprehension or sense of instability in anterior hip region; may be accompanied by pain

Sensitivity / Specificity

0.51 / 0.89

Interpretation

When positive, suggests anterior hip instability or capsular laxity, which may coexist with FAI. High specificity is useful for ruling in instability-related pain.

Scour Test (Quadrant Test)

Procedure

Patient supine with hip flexed and slightly abducted. Examiner applies gentle axial loading to femur while internally and externally rotating the hip through range. Positive if pain localizes to groin.

Positive Finding

Anterior hip, groin, or medial hip pain with axial loading and rotation, particularly during internal rotation phase

Sensitivity / Specificity

0.65 / 0.72

Maslowski et al., 2010, Arthroscopy

Interpretation

Suggests intra-articular pathology including FAI, labral tear, or early osteoarthritis. Moderate sensitivity and specificity; should be combined with other tests.

Log Roll Test (Hip Internal-External Rotation in Supine)

Procedure

Patient supine with hip and knee slightly flexed (~20°). Examiner gently internally and externally rotates hip through available range. Positive if groin pain occurs.

Positive Finding

Anterior hip or groin pain with passive internal rotation, or apprehension with external rotation

Sensitivity / Specificity

0.55 / 0.81

Interpretation

Pain with internal rotation supports FAI; apprehension with external rotation suggests capsular laxity. Useful screening test; low to moderate sensitivity limits use as standalone diagnostic tool.

⚠ Red Flags

  • •Acute severe hip pain with fever suggesting septic arthritis
  • •Progressive neurological deficits in lower limb
  • •Severe unilateral hip pain with night symptoms and systemic symptoms (malignancy concern)
  • •Inability to bear weight acutely
  • •Signs of avascular necrosis (collapse, severe restriction, night pain)
  • •Recent trauma with severe pain and immobility

⚡ Yellow Flags

  • •Fear-avoidance beliefs regarding hip movement and activity
  • •Excessive focus on imaging findings creating catastrophizing
  • •Significant psychological distress or depression affecting rehabilitation adherence
  • •High-level athlete with unrealistic return-to-sport timelines
  • •Pending litigation or workers' compensation claims
  • •Poor coping strategies or passive approach to treatment

Osteopathic Techniques

Region

Hip joint

Technique

Articulation

Rationale

Gentle oscillatory movements in pain-free ranges promote synovial fluid distribution, maintain articular cartilage nutrition, and reduce pain while avoiding impingement positions. Particularly useful in early-stage FAI.

Region

Hip flexors (iliopsoas and rectus femoris)

Technique

Soft Tissue

Rationale

Releases tight hip flexors which paradoxically increase anterior hip joint stress and contribute to impingement mechanics; reduces compensatory patterns and improves hip extension during gait

Region

Gluteal muscles and deep hip rotators

Technique

MET

Rationale

Strengthens and lengthens external rotators and hip stabilizers through muscle energy techniques; restores optimal hip biomechanics and reduces compensatory stress on anterior labrum

Region

Lumbar spine and sacroiliac joints

Technique

HVLA

Rationale

Addresses associated lumbar and pelvic dysfunction that may contribute to altered hip mechanics; improves spinal-pelvic stability reducing proximal compensation at the hip

Region

Hip adductors and medial thigh

Technique

Soft Tissue

Rationale

Releases tight adductors which restrict abduction range and alter hip biomechanics; improves frontal plane stability and reduces dynamic impingement

Region

Lumbo-pelvic-hip complex

Technique

Functional

Rationale

Assesses and treats the hip in functional positions mimicking activities of daily living and sport; identifies compensation patterns and facilitates integrated movement patterns that unload the FAI zone

Add-On Approaches

Chinese Medicine

Acupuncture and moxibustion to Gallbladder and Liver meridians (particularly GB 29, GB 30, LV 3) to improve local circulation and reduce pain; herbal formulas such as Du Huo Ji Sheng Tang to address wind-damp obstruction and stagnation

Chiropractic

Hip joint manipulation if appropriate after imaging; sacroiliac joint adjustments to optimize pelvic stability; femoral head mobilization in non-impingement planes to improve hip arthrokinematics

Physiotherapy

Progressive resistance training for hip stabilizers (gluteus medius and maximus); hip internal rotation strengthening in functional positions; proprioceptive training; gradual return-to-sport protocols based on movement quality assessment

Remedial Massage

Soft tissue therapy to hip flexors, tensor fasciae latae, gluteal muscles, and deep rotators; myofascial release to reduce muscular tension contributing to altered hip mechanics; trigger point therapy for referred pain patterns

Rehabilitation Exercises

Hip external rotation mobilization (supine)

Range of MotionBeginner

Hip flexor stretch (half-kneeling or standing)

StretchingBeginner

Piriformis stretch (supine figure-4)

StretchingBeginner

Gluteus medius activation (side-lying abduction)

StrengtheningBeginner

Clamshells (side-lying external rotation)

StrengtheningBeginner

Bridging with gluteal emphasis

StrengtheningIntermediate

Single-leg Romanian deadlift (RDL)

StrengtheningIntermediate

Single-leg stance on unstable surface

BalanceIntermediate

Quadruped hip rotation (threadthe-needle)

PosturalBeginner

Monster walks with resistance band

StrengtheningIntermediate

Copenhagen adductor squeeze (side-lying)

StrengtheningIntermediate

Swimming or hydrotherapy (non-weight bearing cardio)

CardiovascularIntermediate

Referral Criteria

  • •Imaging evidence of severe labral pathology with mechanical symptoms unresponsive to conservative care for 3+ months
  • •Suspected osteoarthritis progression with imaging confirmation and functional decline
  • •Failure to improve after 6-8 weeks of structured conservative treatment
  • •Mechanical locking or catching limiting function despite conservative management
  • •High-level athletes requiring return-to-sport and considering surgical options
  • •Severe pain limiting activities of daily living despite optimal conservative management
  • •Suspected avascular necrosis or other hip pathology requiring specialist imaging interpretation
  • •Signs of intra-articular loose body or syndromic presentation
  • •Patient anxiety or psychological factors significantly impacting rehabilitation adherence warranting pain psychology referral