Effect of patient-specific instrument on lowering threshold for junior physicians to perform total hip arthroplasty on developmental dysplasia of the hip patients

Purpose To create a patient-specific instrument (PSI) in lowering the surgical experience requirement for junior physicians to perform total hip arthroplasty (THA) on developmental dysplasia of the hip (DDH) patients. Methods Combined with rapid prototyping technology, we created a PSI and established DDH hip model in vitro. We enrolled 48 junior physicians and randomly assigned them into two groups. After creation of the PSI, they performed simulated THA surgery on a full-scale hip model with or without PSI on DDH models. The planned prothesis orientation, post-operative prothesis orientation, and surgery time were recorded. Results The final cup inclination was 42.0 +/- 0.8 degrees in PSI group and 37.8 +/- 2.0 degrees in control group, while final cup anteversion was 16.0 +/- 0.7 degrees in PSI group and 24.7 +/- 3.5 degrees in control group. The oinclination in PSI group was smaller than that in control group (4.2 +/- 0.5 degrees vs 9.5 +/- 1.4 degrees, P < 0.01), so does oinclination (2.9 +/- 0.4 degrees in PSI group vs 15.2 +/- 2.5 degrees in control group, P < 0.01). The outlier percent was 8.3% in PSI group and 70.8% in control group (P < 0.01). At the same time, the PSI group did not prolong the operation time (P = 0.551). Conclusion The PSI can greatly increase the accuracy of placing the cup orientation and lower the threshold for junior physicians to perform THA on DDH patients. It could be a training tool for them to increase their THA surgical skills.