Protocolised MRI as an adjunct to CT in the diagnosis of femoral neck fracture in high energy ipsilateral femoral shaft fractures - A break-even analysis.

Background: In high-energy femoral shaft fractures (FSFs), ipsilateral femoral neck fractures (FNFs) can be missed by conventional trauma computed topography (CT) imaging, resulting in increased treatment costs and patient complications. Preliminary evidence suggests that a rapid, limited-sequence pelvis and hip magnetic resonance imaging (MRI) protocol can identify these occult fractures and be feasibly implemented in the trauma setting. This study aims to establish the economic break-even point for implementing such an MRI protocol in all high-energy FSFs.

Methods: We used an adapted break-even economic tool to determine whether the costs of a targeted MRI protocol can be offset by cost-savings achieved through prevention of missed fractures (thus avoiding prolonged admission and re-operation). Sensitivity analyses were performed to demonstrate reliability of the economic modelling across a range of assumptions.

Results: Assuming a baseline of FNFs missed on CT of 12%, an MRI cost of £129 and cost of treating each missed FNF of £2457.5, the equation yielded a break-even rate of 7% and absolute risk reduction (ARR) of 5%, indicating that for every 100 FSFs, MRI would need to diagnose 5 of the 12 missed FNF to be economically viable (number needed to treat (NNT)=20). Economic viability was maintained even at double the cost of MRI, while increasing the cost of treating each complication served to reduce the ARR further, increasing cost-savings.

Conclusion: A rapid, limited-sequence MRI protocol to exclude occult ipsilateral FNFs in all high-energy FSFs appears to be economically justified measure. Further research exploring the feasibility of such a protocol, as well as the role of intra-operative fluoroscopy in this context, is required.