In a 75-year-old patient with deep thigh pain, which imaging studies are recommended?

Imaging Approach for Deep Thigh Pain in a 75-Year-Old

Start with plain radiographs of the pelvis and hip, followed by MRI of the pelvis and affected hip without contrast if radiographs are negative or equivocal. 1, 2

Initial Imaging: Plain Radiographs

Begin with anteroposterior (AP) radiographs of the pelvis plus orthogonal views of the symptomatic hip (AP with 15 degrees internal rotation and cross-table lateral). 1 This combination is critical because:

• Radiographs detect approximately 90% of proximal femoral fractures and remain the mainstay for initial evaluation 1
• Elderly patients with suspected hip fractures frequently have concomitant pelvic fractures (sacrum, pubic rami) that may occur in isolation or with femoral fractures 1
• The pelvis view allows comparison to the contralateral side for subtle abnormalities 1
• Radiographs can identify osteoarthritis, bone tumors, and other osseous pathology 2

Critical caveat: Negative radiographs alone cannot exclude fracture in this age group—sensitivity is only 90% for hip fractures. 1

Second-Line Imaging: MRI Without Contrast

If radiographs are negative or equivocal but clinical suspicion remains high, proceed immediately to MRI of the pelvis and affected hip without IV contrast. 1 The evidence strongly supports this approach:

• MRI demonstrates 99-100% sensitivity for radiographically occult proximal femoral fractures 1
• Detects 38% of patients with extrafemoral pelvic fractures missed on radiographs 1
• Identifies soft tissue pathology including muscle/tendon injuries, bursitis, enthesopathy, tumors, and referred pain sources 2
• No IV contrast is needed for initial fracture detection 1
• A negative MRI allows confident exclusion of fracture and reduces unnecessary hospital admissions 1

Important note: While a 2026 case report 3 described a rare false-negative initial MRI in a 76-year-old with occult subtrochanteric fracture, this represents an exceptional outlier. The overwhelming evidence supports MRI's near-perfect sensitivity.

Alternative: CT Without Contrast

CT pelvis and hips without contrast serves as a problem-solving modality when:

• MRI is contraindicated (pacemaker, severe claustrophobia, metallic implants)
• MRI is unavailable
• Better fracture morphology characterization is needed for surgical planning 1

However, CT is less sensitive than MRI for occult fractures and soft tissue evaluation. 1

What NOT to Order Initially

• Bone scan: Outdated, time-consuming, may be false-negative for 72 hours post-injury, superseded by CT when MRI contraindicated 1
• Ultrasound: Only 65% specificity for fracture detection, cannot comprehensively evaluate bones 1
• MRI with contrast: No role in initial fracture assessment 1

Clinical Algorithm

1. All patients: AP pelvis + orthogonal hip radiographs
2. If radiographs positive: Proceed to treatment planning (may need CT for surgical planning)
3. If radiographs negative but patient cannot bear weight or has persistent pain: MRI pelvis/hip without contrast
4. If MRI contraindicated: CT pelvis/hips without contrast, consider repeat imaging in 5-7 days if negative 1

Additional Diagnostic Considerations

In this age group with deep thigh pain, maintain awareness of:

• Referred pain from spine (vertebral compression fractures, nerve root pathology) 4
• Deep gluteal syndrome (sciatic nerve entrapment, though typically younger patients) 5, 6
• Soft tissue masses (rare but consider synovial sarcoma even in older adults) 7
• Vascular pathology (though DVT ultrasound is not indicated without specific venous symptoms) 8, 9

The key pitfall to avoid: Discharging a 75-year-old with negative radiographs and persistent inability to bear weight without obtaining MRI. Delayed fracture diagnosis significantly increases 30-day mortality risk in this population. 10