Lateral Patient Positioning and Central Lag Screw Placement in Geriatric Cephalomedullary Nailing

Hip fracture is a debilitating condition in the elderly. Cephalomedullary nails are commonly used to achieve internal fixation in these injuries. Proper screw placement within the femoral head (central or inferior in the coronal plane, central in the lateral plane) lowers the risk of the screw cutting out of the femoral head post-operatively. Traditionally, these nails have been implanted with the patient positioned supine, but some surgeons prefer a lateral patient position. This lets adipose tissue fall away from the incision site, potentially improving the surgeon's ability to achieve a desired nail starting point. Lateral nailing also theoretically provides more control over the aiming arm by preventing its rotation due to gravity. Because relatively little research exists comparing these methods, the purpose of this study was to investigate if lateral patient positioning may be associated with higher rates of central lag screw placement than traditional supine nailing. Patients aged 60 or older receiving a cephalomedullary nail for an intertrochanteric femur fracture between June 2009 and April 2022 were identified via a medical records query of three hospitals (n=465). Lateral intra-operative fluoroscope images were for each patient were de-identified and exported to Microsoft PowerPoint, where a custom overlay was applied to divide each femoral head into perfect thirds. The lag screw tip was determined by inspection to reside in the Anterior, Middle, or Posterior third of the head. Cases in which the minor diameter of the screw was touching the line between thirds were considered Junction Anterior-Middle or Junction Posterior-Middle. To prevent bias, the surgical record was accessed last to determine the position of each patient. Compared to supine positioning, lateral positioning was associated with a 0.493 relative risk of placement not fully within the middle region (p=0.004) and a 0.244 relative risk of placement in extreme anterior and posterior regions (p=0.056). Multivariate linear regression analysis revealed that central screw placement was associated with the following: lateral positioning (p=0.030), older patient age (p=0.009), and larger screw diameter (p=0.014). Analysis of only patients receiving 11mm screws (n=346) produced broadly similar results. We conclude that in geriatric intertrochanteric cephalomedullary nailing, lateral positioning of the patient may be associated with higher rates of central screw placement on the lateral fluoroscopy view. Prospective study design is needed to reduce the influence of confounding variables on these results, including varying levels of surgeon experience with this procedure.