Current Trends in the Evaluation and Management of Nondisplaced Femoral Neck Fractures in the Elderly

Kanu Okike, MD, MPH; Ian G. Hasegawa, MD

Disclosures

J Am Acad Orthop Surg. 2021;29(4):e154-e164. 

In This Article

Imaging

Plain Radiographs

All suspected FN fractures should undergo an initial standard AP pelvis radiograph and a shoot-through lateral hip radiograph. Frog leg lateral images are not recommended because they risk fracture displacement and can also cause patient discomfort. The importance of a high-quality lateral view for evaluating posterior fracture angulation has been highlighted recently.[6,14,15] The posterior tilt angle may be reproducibly measured on the lateral radiograph using the technique described by Palm et al[6] (Figure 2). Recently, posterior displacement on the lateral radiograph taken at the time of injury has emerged as an important predictor of failure after fixation of Garden I and II FN fractures,[6,14,15] as is discussed in detail below.

Figure 2.

Radiograph showing calculation of the posterior tilt angle. According to the method of Palm et al, posterior tilt is measured as the angle (α) between a line drawn along middle of the femoral neck (MCL) and the RCL, which is drawn from the center of a circle drawn over the femoral head (c) to a point at the intersection of the MCL and the aforementioned circle. MCL = midcollum line, RCL = radius collum line. (Reproduced with permission from Palm H, Gosvig K, Krasheninnikoff M, Jacobsen S, Gebuhr P: A new measurement for posterior tilt predicts revision surgery in undisplaced femoral neck fractures: 113 consecutive patients treated by internal fixation and followed for 1 year. Acta Orthop 2009;80:303–307.6)

CT and MRI

Advanced imaging is largely unnecessary when good quality plain radiographs have been obtained. However, various factors can impair fracture visualization on the AP and lateral radiographs, thereby compromising the assessment of fracture displacement. These inhibitory factors include proximal femoral osteopenia, overlying bony and soft-tissue anatomy, suboptimal beam angulation, underpenetration or overpenetration, and inappropriate patient positioning because of pain.

Some studies have demonstrated a role for CT in the evaluation of apparently nondisplaced fractures that are visible on plain radiographs. In particular, previous studies of Garden I fractures evaluated with two- and three-dimensional CT imaging revealed that the fracture line extended through the medial cortex in 70% to 100% of all cases, indicating that the valgus-impacted patterns may not be as stable as previously thought.[16,17] Three-dimensional CT analysis has also demonstrated that substantial rotational and angular displacement is often present, despite being undetectable on plain radiographs.[17] In one recent study, CT evaluation led to a change in management 21% of the time, with most changes representing a conversion from fixation to arthroplasty.[18] Despite these findings, CT is not currently considered a standard of care in the evaluation of Garden I and II FN fractures.

MRI, on the other hand, has been established as the preferred advanced imaging modality for presumed occult hip fractures.[19] The sensitivity of MRI in detecting occult proximal femur fractures has ranged from 97% to 100%, as compared with 83% to 93% for CT.[20] However, MRI is limited by its incompatibility with certain metal implants (eg, pacemakers) and the potential for restrictions in access, which can lead to delays in diagnosis. When MRI is contraindicated or unavailable, fine cut CT may represent an acceptable alternative. In a study of 179 elderly patients with traumatic hip pain and negative radiographs, no occult fracture of the proximal femur was missed on MRI or CT with 1 mm slices.[21] In addition, MRI was associated with a longer time from initial radiographs to further imaging (3.8 versus 1.8 days for CT, P < 0.05) and a longer delay from physician request to the performance of further imaging (1.0 versus 0.3 days, respectively, P < 0.05).

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