Case:

A 75-year-old female slipped and fell on ice while walking to her car, landing on her left side. She was unable to ambulate afterward and complains of left hip pain. On examination, she has tenderness to the left hip without obvious deformity, but she continues to have difficulty ambulating in the Emergency Department. Radiographs of the left hip and pelvis were negative for acute fracture.

Now what?

a. Admit for observation and pain management

b. Order a bone density scan

c. Order a CT scan of the hip

d. Order an MRI of the hip

e. Tell her to walk through the pain and send her home!

What is the clinical concern?

Hip Fractures:

1. Occur twice as often in women compared to men.

2. Most commonly occur in the elderly population secondary to falls.

3. Are complicated by a 5-8 times increase in all-cause mortality in the first 3 months after the injury.

4. May be radiographically occult in 3-38% of cases. [1]

Brief Anatomy Review:

“Hip” = region including head and neck of femur to less trochanter

o Intracapsular fractures = femoral head and neck

o Extracapsular fractures = trochanteric, intertrochanteric, subtrochanteric

Highlights of the H&P:

Remember to assess for deformity, shortening, rotation, laceration, bruising, or instability of the limbs or tenderness of pelvis and sacrum.

Be aware of concurrent intra-abdominal, retroperitoneal, femoral shaft, knee, and urologic injuries in trauma patients.

Don’t forget to assess distal vascular and sensory function (as there may be femoral or sciatic nerve injury, or injury to the femoral vessels).

Think of occult fractures when there is pain with axial loading, the patient had restricted mobility prior to the injury, and the patient is at risk for osteoporosis.

Imaging:

X-ray:

o Identifies fractures, dislocations, and avulsion injuries

o Most hip fractures will be diagnosed by plain radiography

o Hip and pelvis x-rays are 90-98% sensitive for hip fractures. [1]

o Initial imaging should include (at a minimum) anterioposterior and lateral x-ray views of hip in addition to an anteroposterior view of the pelvis

o Don’t forget! Imaging of femoral shaft to assess joint above and below injury

MRI:

o In patients with pain with weight bearing but unremarkable radiographs, there should be suspicion for occult fracture, especially of the femoral neck or acetabulum. Consider obtaining MRI imaging.

o Nondisplaced fractures, insufficiency fractures (stress/incomplete fractures) of the femoral neck may not be seen on radiographs.

o Obtain MRI imaging in the ED or, if unavailable, obtain MRI within 24-48 hrs while patient remains non-weight-bearing, in conjunction with orthopedic consultation.

o In a study by Cabarrus et al [4], CT and MRI were compared in diagnosing pelvic and proximal femur insufficiency fractures; MRI found 128/129 (99%) of fractures in 63/64 (98%) patients compared to CT which identified 89/129 (69%) of fractures in 34/64 (53%) of patients. They found, in particular, femoral head and acetabular fractures were better detected with MRI.

o In study by Dominguez et al [2], 11.4% of patients with negative initial plain films underwent MRI (62/545). 38% of those patients were found to have hip fractures (24/62), resulting in 4.4% of patients with negative initial x-rays having occult hip fractures.

o MRI confers the additional advantage of identifying fractures immediately rather than waiting several days for repeat x-ray imaging.

CT:

o Pelvic fractures that involve the acetabulum, pelvic ring, and sacrum are difficult to identify with plain radiographs, so CT imaging is recommended.

o May not detect hip fractures, especially in the setting of osteoporosis in which MRI performs better.

o May be used for pre-operative planning of hip fractures in certain cases

Take Home Point:

Be suspicious for occult hip fracture in elderly patients with hip pain and difficulty ambulating following a fall or other trauma.  Plain radiographs may be unrevealing, in which case MRI is the preferred imaging modality.

Faculty Reviewer: 

Dr. Jeff Feden

References:

1. J Tintinalli. Tintinalli’s Emergency Medicine: A comprehensive study guide 8th ed. 2016

2. Dominguez, S. Prevalence of traumatic hip and pelvic fractures in patients with suspected hip fractures and negative initial standard radiographs – a study of ED patients. Academic Emergency Medicine. 2005 April; 12 (4): 366-9.

3. Frihagen, F. MRI diagnosis of occult hip fractures. Acta Orthopeadica. 2005 Aug; 76 (4): 524-530.

4. Cabarrus, M. MRI and CT of Insufficiency Fractures of the Pelvis and Proximal femur. AJR. 2008 Oct; 995-1001.

5. Verbeeten, MK. The advantages of MRI in the detection of occult hip fractures. Eur Radiology. 2005 Jan; 15 (1): 165 – 9.

6. Evans PD. Comparsion of MRI with bone scanning for suspected hip fracture in elderly patients. The Bone and Joint Journal. 1994 Jan; 74 (1); 158-9.

7. Jude, C. Radiographic evaluation of the painful hip in adults. Up to date. Feb 2016.