2D vs 3D planning for THA is an ongoing debate amongst orthopaedic surgeons. 2D planning is simple, requires minimal patient imaging and can be efficiently produced. Alternatively, 3D planning can provide more robust simulation tools and has higher implant templating sizing accuracy1. There are concerns about the cost and radiation associatied with CT scans for these 3D plans3. The purpose of this study was to compare 2D and 3D pre-operative plans to identify if and when 3D planning is needed. 2D and 3D planning was retrospectively completed for 42 patients who underwent total hip replacement. Patients were grouped based on 2D spinopelvic mobility outputs: Group A patients had one or more spinopelvic risk factors and Group B patients had normal spinopelvic risk factors. During the 3D planning stage, patients were assessed based on 11 different simulated activities of daily living (ADL). 40% of patients in Group A failed at least one of the simulation activities, compared to none of the patients in Group B. All patients who failed the simulations had at least two spinopelvic risk factors. Bone-bone impingement was observed in 67% of the failed ADL simulations while implant-implant impingement was observed in 50%. The twist simulation was the most common ADL resulting in failure due to lesser trochanter-ischium impingement. Using spinopelvic risk factors, we can identify the 10% of patients who may benefit from 3D planning. These results show that 3D planning did not provide any new insights for 90% of patients. Therefore, 2D planning is sufficient for the majority of THA patients; and if we use 2D planning to identify those who need 3D planning, we could avoid the cost and radiation associated with 3D planning in 90% of patients without any reduction in quality of patient care.
Walter et al. (Thu,) studied this question.