Cost-Effectiveness Of Pre-Operative Spinal Imaging For Suspected Stiff Or Hypermobile Spine Before Total Hip Arthroplasty

The risk of instability, dislocation, and revision following total hip arthroplasty (THA) is increased in patients with abnormal spinopelvic mobility. Seated and standing lateral lumbar spine imaging can identify patients with either stiff or hypermobile spine (SHS) to guide interventions such as changes in acetabular cup placement or use of a dual-mobility hip construct aimed at reducing dislocation risk. We hypothesized that routine preoperative spinal imaging (PSI) for all patients undergoing THA would be a cost-effective method to lower rates of instability after THA. A state-transition Markov decision model was created to compare routine preoperative spinal imaging versus no screening in patients with and without SHS. Screened patients with SHS were assumed to receive dual mobility hardware while those without SHS and non-screened patients were assumed to receive conventional THA. The baseline prevalence of SHS, PSI sensitivity and specificity, and transition probabilities were derived from the literature. Cost-effectiveness was estimated with the incremental cost-effectiveness ratio and effectiveness measured as quality-adjusted life years (QALYs) with $100,000 per additional QALY as the threshold for cost-effectiveness. One-way sensitivity analyses were performed for all model parameters and two-way sensitivity analysis examined pairs of parameters, including costs, sensitivity and specificity of PSI, and probability of dislocation. The screening strategy for SHS with PSI had a lifetime cost of $12,515 and QALY gains of 16.91 compared with no-screening ($13,331 and 16.77). The PSI strategy reached cost-effectiveness at 5 years and was dominant at 11 years following THA. In sensitivity analyses PSI remained the dominant strategy if prevalence of SHS was >1.9%, cost of PSI was