Femoroacetabular Impingement
Lower LimbOverview
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
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
Reference: Maslowski E, Sullivan W, Forster Harwood J, Gonzalez P, Kaufman M, Vidal A, Akuthota V. The diagnostic validity of hip provocation maneuvers to detect intra-articular hip pathology. PM R 2010;2(3):174-81; PMID 20359681
Interpretation
Pain on scouring suggests an intra-articular source, but the test is weak both ways — 50-62% sensitive, 29-38% specific — so a negative does not exclude and most positives are false alarms. Use it alongside FADIR, FABER, internal rotation range and imaging. Scour with adduction is also one of the five Sutlive hip osteoarthritis predictors, valuable only in combination with the other four.
FABER Test (Flexion-Abduction-External Rotation)
Procedure
Patient supine; examiner flexes, abducts, and externally rotates the hip, then applies gentle overpressure.
Positive Finding
Anterior groin or hip pain at end-range of flexion, abduction, and external rotation
Related reference: Maslowski E, Sullivan W, Forster Harwood J, Gonzalez P, Kaufman M, Vidal A, Akuthota V. The diagnostic validity of hip provocation maneuvers to detect intra-articular hip pathology. PM R 2010;2(3):174-81; PMID 20359681
Interpretation
Sensitive but not specific (around 0.82 / 0.38 or below): a positive FABER means the hip joint is a plausible source, not that femoroacetabular impingement is the cause — it cannot separate impingement from labral pathology, capsular irritation or early osteoarthritis. Groin or anterior hip pain is the meaningful response; lateral pain suggests an extra-articular source. Combine with the anterior impingement test, restricted internal rotation in flexion, and imaging.
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
Related reference: Reiman MP, Goode AP, Cook CE, Hölmich P, Thorborg K. Diagnostic accuracy of clinical tests for the diagnosis of hip femoroacetabular impingement/labral tear: a systematic review with meta-analysis. Br J Sports Med 2015;49(12):811; PMID 25515771
Interpretation
Reproduction of sharp anterior groin pain in this position is consistent with anterior femoroacetabular impingement, but the test is provocative rather than diagnostic and is positive across the range of intra-articular hip pathology. Cam and combined-type morphology can only be established on imaging. Treat a positive test as an indication to image, not as confirmation of FAI.
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
Interpretation
Apprehension or a sense of instability in extension with external rotation raises the possibility of anterior hip microinstability or capsular laxity, which can coexist with femoroacetabular impingement and can change management. No validated diagnostic-accuracy figures support this test, so treat a positive result as a prompt to assess for generalised laxity and consider imaging, not as evidence of instability.
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
Interpretation
The log roll moves the femoral head within the acetabulum with the surrounding musculature relaxed, so a painful or restricted result points to the joint and capsule rather than to muscle or tendon. That relative specificity for an intra-articular source is its only real strength. It is NOT a screening test — sensitivity is low, so a normal log roll does not exclude femoroacetabular impingement. Use FADIR to screen.
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
Reference: Reiman MP, Goode AP, Cook CE, Hölmich P, Thorborg K. Diagnostic accuracy of clinical tests for the diagnosis of hip femoroacetabular impingement/labral tear: a systematic review with meta-analysis. Br J Sports Med 2015;49(12):811; PMID 25515771
Interpretation
The best available screening test for intra-articular hip pathology, and a poor confirmatory one. Pooled sensitivity 0.94-0.99, so a negative FADIR makes femoroacetabular impingement or labral pathology unlikely — that is the informative result. A positive is weak on its own: specificity is low, and the test is frequently positive in asymptomatic hips, osteoarthritis and labral tears. Pair with FABER, restricted internal rotation in flexion, and imaging.
⚠ 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
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
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
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
Hip adductors and medial thigh
Technique
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
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)
Hip flexor stretch (half-kneeling or standing)
Piriformis stretch (supine figure-4)
Gluteus medius activation (side-lying abduction)
Clamshells (side-lying external rotation)
Bridging with gluteal emphasis
Single-leg Romanian deadlift (RDL)
Single-leg stance on unstable surface
Quadruped hip rotation (threadthe-needle)
Monster walks with resistance band
Copenhagen adductor squeeze (side-lying)
Swimming or hydrotherapy (non-weight bearing cardio)
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