Diagnostic Imaging for Suspected Hip Fractures

Initial Imaging Protocol

• The American College of Radiology recommends that the standard radiographic approach should include an anteroposterior (AP) view of the pelvis with a cross-table lateral view of the symptomatic hip for patients with suspected hip fractures, allowing for optimal diagnostic information and detection of both hip and pelvic fractures 1, 2
• For suspected hip fractures, orthogonal views are essential for proper diagnosis, typically consisting of an AP view with approximately 15 degrees of internal rotation and a cross-table lateral view, as recommended by the American College of Radiology 3, 4

Rationale for Combined Imaging

• Patients with clinically suspected proximal femur fracture often have concomitant fractures of the pelvis, including the sacrum and pubic rami, highlighting the importance of comprehensive imaging, according to the American College of Radiology 1, 2
• The inclusion of a pelvis radiograph allows for comparison of potential abnormalities to the contralateral asymptomatic side, which is crucial for accurate diagnosis, as stated by the American College of Radiology 1, 2

Limitations and Follow-up Imaging

• Despite being the mainstay for initial imaging, both pelvis and hip radiographs have limitations in sensitivity and specificity for fracture detection, with approximately 10% of proximal femoral fractures not being identified on initial radiographs, according to the American College of Radiology 1, 3
• When radiographs are negative but clinical suspicion remains high, MRI without IV contrast is the recommended next imaging study, as suggested by the American College of Radiology 5, 4

Special Considerations

• Delays in diagnosis and treatment are associated with increased cost, complication rates, length of hospital stay, and short- and long-term mortality, making accurate initial imaging crucial, as emphasized by the American College of Radiology 2, 3

Common Pitfalls to Avoid

• Relying solely on hip radiographs without including pelvis views may miss associated pelvic fractures, which can lead to altered treatment decisions, as warned by the American College of Radiology 1, 5
• Failing to obtain orthogonal views can lead to missed fractures and potentially altered treatment decisions, highlighting the importance of comprehensive imaging, according to the American College of Radiology 3, 4

Imaging Modalities for Hip Fracture Diagnosis

Introduction to Hip Fracture Imaging

• The American College of Radiology recommends MRI without IV contrast as the definitive imaging modality for ruling out hip fracture when radiographs are negative but clinical suspicion remains high, demonstrating near 100% sensitivity compared to CT's significantly lower accuracy 6, 7
• Radiographs identify approximately 90% of proximal femoral fractures, with a sensitivity of 90% 7, 8

Diagnostic Performance of MRI and CT

• MRI has a sensitivity of 99-100% for proximal femoral fractures, with coronal STIR sequence alone demonstrating 100% sensitivity 6, 9
• CT is explicitly "not as sensitive as MRI" per ACR guidelines, with significant diagnostic failures and high inter-observer variability 6, 7, 8
• MRI accurately depicts fracture extent, guiding conservative versus surgical management, and detects concomitant pelvic fractures and soft tissue injuries 6, 9, 8

Clinical Impact of Accurate Diagnosis

• Surgical delays >12 hours significantly increase 30-day mortality risk, and delays in diagnosis increase costs, complication rates, and hospital length-of-stay 10
• MRI enables confident emergency department discharge when negative, reducing unnecessary admissions, and rapid diagnosis of surgical fractures allows timely treatment with improved outcomes 6, 9
• MRI accurately characterizes fracture morphology, including intertrochanteric extension of seemingly isolated greater trochanter fractures, guiding treatment planning 6, 9, 8

Treatment Planning and CT Considerations

• MRI accurately depicts fracture extent, guiding conservative versus surgical management, and incomplete intertrochanteric fractures may be treated conservatively when properly characterized 6, 9, 8
• CT has limited advantages over MRI, including faster acquisition time and usability in patients with significant confusion or MRI contraindications, but its diagnostic inferiority makes it less preferred 9
• The ACR explicitly reserves CT only as a "problem-solving modality following radiography" for better depicting fracture morphology in already-identified fractures, not for ruling out occult fractures 6, 7, 8

Imaging Strategies for Occult Femoral Fractures

Indications for Advanced Imaging

• In adults who present with acute hip or groin pain after minimal trauma (e.g., a fall from standing height) and have negative standard AP pelvis + cross‑table lateral radiographs, further imaging is required because plain films miss roughly 10 % of proximal femoral fractures. [American College of Radiology] 11

MRI as the Gold‑Standard Modality

• Sensitivity: MRI without intravenous contrast detects occult femoral fractures with 99‑100 % sensitivity, making it the definitive test when clinical suspicion persists after negative radiographs. [American College of Radiology] [11][12]
• Protocol: A rapid protocol using a coronal STIR sequence alone achieves 100 % sensitivity; adding a coronal T1‑weighted sequence improves specificity and confidence in fracture characterization. [American College of Radiology] 12
• Diagnostic scope: MRI visualizes bone‑marrow edema and early stress‑related changes before a fracture line appears, accurately distinguishes incomplete from complete fractures, identifies intertrochanteric extension of isolated greater‑trochanter lesions, and detects associated pelvic or soft‑tissue injuries with ≈ 99 % sensitivity. [American College of Radiology] [11][12]

CT as an Alternative When MRI Is Unavailable

• Sensitivity range: Non‑contrast CT provides 87‑94 % sensitivity for occult femoral fractures, substantially lower than MRI. [American College of Radiology] [11][12]
• Performance limitations: In comparative series, CT missed 6 of 15 fractures (≈ 40 % false‑negatives); it frequently fails to detect incomplete fractures such as Garden I femoral‑neck lesions. [American College of Radiology] [11][12]
• Appropriate use: CT is acceptable only when MRI is contraindicated (e.g., pacemaker, severe claustrophobia, extensive metallic implants) or when the patient cannot remain still for the longer MRI acquisition. [American College of Radiology] [11][12]
• Follow‑up requirement: If CT is negative but clinical suspicion remains high, a subsequent MRI is mandatory to rule out missed fractures. [American College of Radiology] 11

Clinical Clues Suggesting an Occult Fracture

• Prodromal dull or aching pain in the groin or thigh that precedes the acute event is a warning sign of an occult femoral fracture. [American College of Radiology] 13

Bilateral Assessment in Patients on Long‑Term Bisphosphonates

• In individuals receiving prolonged bisphosphonate therapy, bilateral femoral imaging is advised because ≈ 30 % develop simultaneous atypical fractures of both hips. [American College of Radiology] 13