SAEM Clinical Images Series: Enigmatic Traumatic Hip Pain
An 84-year-old female presented with a chief complaint of right hip pain after a fall 12 hours prior to presentation. The patient reported a history of falls resulting in shoulder, rib, and left hip fractures in the past. The patient stated that upon getting out of bed, she took 4-5 steps, lost her balance, and fell backward onto the bedroom floor. She denied loss of consciousness. She denied syncope or vertigo before the fall. She was unable to bear weight due to a 7/10 intensity pain on the anterior medial aspect of her right thigh that was worse with movement.
Vitals: 37.8°C; BP 138/92; HR 94; RR 18; SpO2 98% on room air; BMI 24
General: A&Ox4, anxious, in moderate distress.
HEENT: Normocephalic, atraumatic, PERRLA, EOM’s intact.
Cardiac: RRR w/out m/r/g, pulses 2+ in all extremities.
Respiratory: BBS, CTA.
Abdomen: BS+, nondistended, nontender.
MSK: No gross deformities appreciated, right hip with limited flexion and extension due to pain. Tender to palpation superior, anterior medial aspect of the right thigh. Full range of motion of the right knee, ankle, and left lower extremity.
Complete blood count (CBC): Within normal limits
Comprehensive metabolic panel (CMP): Within normal limits
AP Pelvis Radiograph (Figure 1): “Osteopenia with no acute fractures or dislocation”
Occult femur fracture
Occult fractures are defined as fractures that cannot be detected by standard radiographic examination until weeks after the injury either due to lack of displacement or limitations of the imaging study. Occult femur fractures account for 2-10% of total hip fractures and have an associated one-year mortality of 14-16% even when surgically repaired within two days. Delayed recognition coupled with patient immobility may lead to complications such as pulmonary emboli that have been shown to increase one-year mortality by up to 30%.
Magnetic Resonance Imaging
In our case, computed tomography with 3D reconstruction (Figures 2,3) revealed a non-displaced intertrochanteric fracture with involvement of the greater and lesser trochanters. As CT scanning is usually more readily available than MRI, it may be the first additional imaging choice when radiographs are normal. A normal CT scan, however, especially in patients with osteopenia is considered insufficient to rule out an occult fracture. In a 7-year retrospective analysis at a regional trauma center, 57.4% of cases were diagnosed by MRI and 14.6% were diagnosed by CT scan within the first 24 hours. Of the remaining portion, a final diagnosis was made 72 hours after presentation with CT scan (39% of false negative cases) or MRI (61% of false negative cases).
Take-Home Points
- Occult fractures are an important differential when standard imaging modalities do not correlate with physical exam findings.
- Occult fractures can be missed on X-rays and CT scans, delaying definitive treatment. Delayed diagnosis can result in further complications and increased mortality and morbidity.
- MRI is considered the gold standard for identifying occult fractures.
- Deleanu B, Prejbeanu R, Tsiridis E, Vermesan D, Crisan D, Haragus H, Predescu V, Birsasteanu F. Occult fractures of the proximal femur: imaging diagnosis and management of 82 cases in a regional trauma center. World J Emerg Surg. 2015 Nov 18;10:55. doi: 10.1186/s13017-015-0049-y. PMID: 26587053; PMCID: PMC4652353.
- Jonathan Grammer, Michael Sternberg. Occult femur fracture. Visual Journal of Emergency Medicine. Volume 14, 2019, Pages 15-16, ISSN 2405-4690