What are the potential causes of lateral thigh pain in a physically active individual, possibly with a history of trauma, or an older adult with a history of smoking?

Causes of Lateral Thigh Pain

Lateral thigh pain has a broad differential diagnosis that must be systematically evaluated, starting with exclusion of serious pathology, followed by assessment of the most common causes: meralgia paresthetica (lateral femoral cutaneous nerve entrapment), greater trochanteric pain syndrome, referred pain from lumbar spine or hip pathology, and less commonly vascular or intra-abdominal causes.

Immediate Red Flags to Exclude First

• Peripheral artery disease (PAD) presenting as claudication—aching, burning, or cramping pain in the thigh that occurs with walking and resolves within 10 minutes of rest 1
• Stress fractures characterized by insidious onset, night pain, constitutional symptoms, and inability to bear weight 1
• Tumors or infections presenting with night pain, progressive worsening, and constitutional symptoms 1
• Deep vein thrombosis with entire leg swelling, tight bursting pain that worsens with activity and persists at rest 1
• Obturator hernia (rare but important)—can present as lateral thigh pain, particularly in elderly women, and requires imaging of the pelvis/inguinal region 2

Primary Causes of Lateral Thigh Pain

Meralgia Paresthetica (Lateral Femoral Cutaneous Nerve Entrapment)

• Presentation: Numbness, tingling, and burning pain in the lateral aspect of the thigh without motor weakness 3
• Mechanism: Entrapment or compression of the lateral femoral cutaneous nerve, typically at the inguinal ligament 3
• Risk factors: Obesity, tight clothing, pregnancy, diabetes, prolonged standing 4
• Diagnosis: Clinical diagnosis based on sensory symptoms in the lateral thigh distribution without motor involvement 3

Greater Trochanteric Pain Syndrome (GTPS)

• Presentation: Lateral hip and thigh pain that may radiate down the lateral thigh, worse with lying on affected side, difficulty sleeping, and pain with walking 5, 6
• Components: Includes greater trochanteric bursitis, gluteal tendinopathy, iliotibial band syndrome, and abductor mechanism pathology 6
• Physical exam findings: Tenderness over greater trochanter, reproduction of pain with flat palpation of lateral hip and thigh, weakness of hip abductors 5
• Common in: Active individuals, particularly runners and those with repetitive hip movements 6

Referred Pain from Lumbar Spine

• Presentation: Sharp lancinating pain radiating down the leg, often present at rest, induced by sitting, standing, or walking 1
• Most common levels: L2-L3 radiculopathy causing lateral thigh pain 4
• Physical exam: History of back problems, worse with sitting, relief when supine or standing 1
• Critical consideration: Must screen lumbar spine as competing musculoskeletal source in all cases of lateral thigh pain 1, 4
• Lumbar facet syndrome can refer pain to the lateral thigh without classic radicular symptoms 4

Hip Pathology with Referred Pain

• Hip osteoarthritis: Lateral hip and thigh aching discomfort, exacerbated by activity, relieved by rest, pain with internal rotation of hip 1
• Femoroacetabular impingement (FAI) syndrome: Groin pain that can radiate to lateral thigh, particularly in young and middle-aged active adults 7, 8
• Acetabular labral tears: Sharp catching pain that may radiate to lateral thigh, often coexists with FAI 8
• Key differentiator: Hip pathology typically causes groin pain primarily, but can refer to lateral thigh 1

Nerve Entrapment Syndromes

• Subcostal nerve entrapment: Can cause lateral thigh pain, diagnosed with selective nerve blocks 4
• Lateral cutaneous branches of iliohypogastric nerve: Entrapment causes lateral thigh pain, confirmed with neuroblockade 4

Musculotendinous Causes

• Hip abductor muscle strain: Tenderness over gluteus medius/minimus, pain with resisted hip abduction 4
• Iliotibial band syndrome: Lateral thigh pain in runners, tenderness along IT band, pain with hip adduction 5, 6
• Trigger points: Active trigger points in lateral hip and thigh muscles can cause chronic lateral thigh pain 5

Less Common but Important Causes

• Undisplaced femoral neck fracture: Particularly in elderly or those with osteoporosis, may present as lateral thigh pain without obvious trauma 4
• Adiposa dolorosa: Painful subcutaneous fat deposits causing lateral thigh pain 4
• Obturator hernia: Rare cause, particularly in elderly women, requires high index of suspicion and pelvic imaging 2

Diagnostic Algorithm

Step 1: Clinical Assessment

• Exclude red flags through history: night pain, constitutional symptoms, inability to bear weight, progressive worsening 1
• Characterize pain pattern: Burning/tingling suggests nerve entrapment; aching suggests musculoskeletal; claudication pattern suggests vascular 1, 3
• Assess risk factors: Age ≥65 years, smoking, diabetes for PAD; obesity, tight clothing for meralgia paresthetica 1, 3

Step 2: Physical Examination

• Palpation: Tenderness over greater trochanter (GTPS), lateral thigh sensory changes (meralgia paresthetica), trigger points 5, 6
• Hip examination: Range of motion, internal rotation pain (hip pathology), FADIR test (FAI syndrome) 1, 8
• Lumbar spine screening: Mandatory in all cases to rule out referred pain 1, 4
• Vascular examination: Femoral and popliteal pulses, vascular bruits, asymmetric hair growth if PAD suspected 1
• Neurologic examination: Sensory testing in lateral thigh distribution, motor strength testing 3

Step 3: Imaging Protocol

• First-line imaging: Plain radiographs of hip and pelvis to exclude fracture, osteoarthritis, or bony pathology 1
• Advanced imaging: MRI of hip for intra-articular pathology if radiographs inconclusive 1
• Lumbar spine imaging: If radiculopathy suspected based on clinical examination 4
• Vascular testing: Ankle-brachial index if PAD suspected 1
• Pelvic/inguinal imaging: CT or ultrasound if obturator hernia suspected, particularly in elderly women with acute presentation 2

Critical Clinical Pitfalls

• Do not assume trochanteric bursitis without excluding referred pain from lumbar spine, hip pathology, or nerve entrapment—these are common mimics of "pseudotrochanteric bursitis" 4
• Always screen the lumbar spine as L2-L3 radiculopathy commonly presents as lateral thigh pain without back pain 4
• Consider age-specific pathology: SCFE in adolescents/young adults, stress fractures in active individuals, obturator hernia in elderly women 1, 2
• Meralgia paresthetica is purely sensory—presence of motor weakness indicates a different diagnosis 3
• Hip pathology can present as thigh pain rather than groin pain, particularly in older adults 1
• Vascular claudication must be excluded in patients ≥50 years with risk factors before attributing pain to musculoskeletal causes 1