Validity and reliability of preoperative templating in total hip arthroplasty using a digital templating system

To evaluate the validity, interobserver reliability, and intraobserver reproducibility of a digital templating system, the Mdesk (TM) in preoperative templating in cemented and reverse hybrid total hip arthroplasty (THA). Validity was evaluated by comparing the planned cup size, stem size, CCD angles, and neck length with the components used in 129 patients operated with cemented and reverse hybrid THA. The reliability was measured by comparing the templating results of two surgeons with each other (interobserver) and the results of two templatings carried out by first surgeon (intraobserver). The leg length discrepancy was measured before and after the operation to assess the templating ability to correct it. The Mdesk (TM) system showed good validity (kappa value ranged from 0.64 to 0.96), especially when one size over and under the planned size were included. No difference between cemented and cementless stems was found. The interobserver reliability ranged from fair (kappa 0.23) to substantial (kappa 0.61) while the intraobserver reproducibility ranged from substantial (kappa 0.70) to excellent (kappa 0.82). Templating and intraoperative measures succeeded to restore the leg length. The Mdesk (TM) system has comparable validity and reliability with other templating systems used in clinical practice. We recommend that the same surgeon who does the preoperative radiographic templating to also perform the operation. Further studies are required to evaluate the results of succeeded templating in the long run.