What is the difference between Femoroacetabular Impingement (FAI) and Greater Trochanteric Pain Syndrome (GTPS)?

Femoroacetabular Impingement vs Greater Trochanteric Pain Syndrome: Key Differences

Femoroacetabular impingement (FAI) syndrome and greater trochanteric pain syndrome (GTPS) are fundamentally different conditions affecting distinct anatomical structures: FAI is an intra-articular hip joint disorder causing groin pain from abnormal bone contact, while GTPS is a periarticular lateral hip condition involving the gluteal tendons and trochanteric bursa.

Anatomical Location and Pathophysiology

FAI Syndrome

• Intra-articular pathology involving abnormal contact between the femoral head and acetabular rim during hip motion 1
• Results from cam morphology (femoral head-neck junction abnormality), pincer morphology (acetabular overcoverage with LCEA >40°), or mixed patterns 2
• Causes repetitive mechanical loading leading to labral tears, chondral damage, and early osteoarthritis 1

GTPS

• Periarticular lateral hip pathology involving structures outside the hip joint 3, 4
• Encompasses gluteus medius/minimus tendinopathy or tears, trochanteric bursitis, and external snapping hip syndrome 5, 3
• Results from hip abductor weakness, faulty pelvic mechanics, or overuse 5, 6

Pain Location and Characteristics

FAI Syndrome

• Primary location: Groin pain is the hallmark symptom 1
• Secondary locations: May radiate to back, buttock, or thigh 1
• Critical diagnostic point: Absence of groin pain helps exclude FAI syndrome 1
• Pain is motion-related, worsened by hip flexion, adduction, and internal rotation 1

GTPS

• Primary location: Lateral hip and thigh pain 3, 6
• Pain radiates along the lateral thigh to the knee and occasionally below the knee or to the buttock 6
• Point tenderness over the posterolateral greater trochanter on palpation 6
• Pain worsened by lying on the affected side, climbing stairs, or prolonged standing 3, 6

Physical Examination Findings

FAI Syndrome

• Positive FADIR test (flexion-adduction-internal rotation), though a negative test helps rule out hip-related pain 1
• Limited hip internal rotation and flexion 7
• Pain reproduced with hip flexion combined with internal rotation 1

GTPS

• Point tenderness over the greater trochanter on direct palpation 6
• Pain with resisted hip abduction or external rotation 3
• Positive Trendelenburg sign may be present with gluteal tendon tears 3, 4
• No groin pain or positive FADIR test 4, 6

Diagnostic Imaging Approach

FAI Syndrome

• Initial imaging: AP pelvis and lateral femoral head-neck radiographs (Dunn, frog-leg, or cross-table views) 1
• Advanced imaging: MRI or MR arthrography to assess labral tears, chondral damage, and ligamentum teres pathology 1, 2
• Key measurements: LCEA >40° for pincer morphology, alpha angle for cam morphology 2
• Critical caveat: Never diagnose based on imaging alone—cam/pincer morphology is common in asymptomatic individuals 2, 8

GTPS

• Clinical diagnosis: Physical examination is primary, imaging not required for diagnosis 3, 9
• Radiographs: May show calcific tendinopathy or rule out other pathology 3
• MRI: Useful to confirm gluteal tendon tears or exclude alternative diagnoses, but not necessary for diagnosis 3

Patient Demographics

FAI Syndrome

• Young to middle-aged active adults (typically 20-50 years) 1
• Athletes and active individuals with repetitive hip flexion activities 1

GTPS

• Higher prevalence in women 6
• Associated with obesity, low back pain, osteoarthritis, and iliotibial band tenderness 6
• Incidence approximately 1.8 per 1000 patients per year 6

Treatment Approaches

FAI Syndrome

• Conservative trial: 3-6 months of activity modification, physical therapy, and NSAIDs 2
• Surgical indications: Failed conservative management with persistent symptoms, or MRI-confirmed labral/chondral damage 2
• Surgical technique: Hip arthroscopy with acetabular rim trimming and labral management 2

GTPS

• First-line: Physical therapy targeting hip abductor strengthening and pelvic control, NSAIDs, activity modification 3, 6, 9
• Second-line: Corticosteroid injections into trochanteric bursa or peritendinous space 3, 6, 9
• Surgical management: Reserved for chronic symptoms refractory to 6+ months of conservative therapy 3

Critical Diagnostic Pitfalls

Both conditions can coexist: Up to one-third of FAI patients have concurrent gluteus medius pathology 4. When both anterior (groin) and lateral hip pain are present, evaluate and treat both conditions 4.

Always screen competing sources: Lumbar spine pathology must be excluded in all hip pain evaluations, as radicular pain can mimic both conditions 1, 7, 8.

Imaging findings don't equal disease: Incidental findings are extremely common in asymptomatic individuals for both FAI morphology and gluteal tendon changes—clinical correlation is mandatory 2, 8.