What is the differential diagnosis for a patient with left hip pain that is relieved by wrapping an ace (elastic bandage) wrap around the upper thigh?

Differential Diagnosis: Hip Pain Relieved by Compression

The most likely diagnosis is acetabular dysplasia and/or hip instability, given that compression with an elastic wrap provides symptomatic relief—this suggests the hip joint benefits from external stabilization due to underlying structural instability. 1

Primary Diagnostic Considerations

Acetabular Dysplasia/Hip Instability (Most Likely)

• Misalignment between the femoral head and acetabulum results in instability and overload of the acetabular rim during normal activities 1
• Pain relief with compression wrapping strongly suggests the joint benefits from external stabilization, which is pathognomonic for instability 2
• Patients typically report a sensation of instability or "giving way" in addition to medial groin pain 3
• Apprehension with provocative maneuvers is common on examination 3
• This diagnosis requires AP pelvis and lateral femoral head-neck radiographs to assess bony morphology, specifically measuring the center-edge angle 1

Femoroacetabular Impingement (FAI) Syndrome (Consider Second)

• Characterized by groin pain with hip flexion, adduction, and internal rotation movements 1
• Associated with cam, pincer, or mixed morphology on imaging representing symptomatic premature contact between the proximal femur and acetabulum 1
• Pain may be felt in the groin, back, buttock, or thigh—not exclusively groin pain 1
• The FADIR test (flexion-adduction-internal rotation) is recommended for screening despite limited diagnostic accuracy; a negative test helps rule out hip-related pain 1
• Less likely than instability given the compression relief pattern, but FAI and labral pathology commonly coexist with dysplasia 1, 3

Acetabular Labral Tear (Often Coexists)

• Presents with sharp, catching pain in the groin/medial hip with mechanical symptoms 3
• Labral tears frequently coexist with FAI syndrome or acetabular dysplasia rather than occurring in isolation 1, 3
• Requires MRI or MRA for definitive diagnosis of intra-articular structures 1

Critical Exclusions Required First

Before pursuing the above diagnoses, you must exclude serious pathological conditions: 1

• Stress fractures (femoral neck or pubic ramus): insidious onset, night pain, inability to bear weight, focal bone tenderness 3
• Tumors: night pain, constitutional symptoms, progressive worsening 3
• Infection (septic arthritis, osteomyelitis): acute onset, fever, inability to bear weight, severe pain at rest 3
• Slipped capital femoral epiphysis (SCFE): critical in adolescents/young adults, often presents as medial thigh or knee pain with external rotation deformity 3, 4

Competing Musculoskeletal Sources

Lumbar spine pathology must be screened in all cases of hip pain 1, 3

• Sharp lancinating pain radiating to the medial thigh, induced by sitting, standing, or walking 3
• Hip pathology can present as knee pain, and spine pathology can present as hip pain 3, 5

Diagnostic Algorithm

Step 1: Exclude Red Flags

• Assess for night pain, constitutional symptoms, inability to bear weight, fever, or external rotation deformity 3, 5
• Determine if pain is activity-related or present at rest 3

Step 2: Physical Examination

• Perform FADIR test to assess for intra-articular pathology 1
• Evaluate hip range of motion, particularly internal rotation 3
• Mandatory lumbar spine screening in all cases 1, 3
• Assess for apprehension with provocative maneuvers suggesting instability 3

Step 3: Imaging Protocol

• First-line: AP pelvis and lateral femoral head-neck radiographs (Dunn view, frog-leg view, or cross-table view) 1
• Advanced imaging (MRI or MRA) for intra-articular structures when radiographs are inconclusive or surgery is considered 1
• Diagnosis should never be made on imaging alone—clinical correlation is mandatory 1

Critical Clinical Pitfalls

• Incidental imaging findings are extremely common in asymptomatic individuals and must be interpreted with clinical sensitivity 1, 3
• Coexisting pathology is the rule rather than the exception—labral tears often coexist with FAI or dysplasia 1, 3
• Clinical examination and diagnostic imaging both have limited diagnostic utility when used in isolation; a comprehensive approach combining symptoms, clinical signs, and imaging is essential 1, 5
• The specific finding of pain relief with compression wrapping is highly suggestive of underlying instability requiring external stabilization 2