Design of Well-Matched End-Structure of Anatomical Proximal Femoral Locking Plate Based on Computer-Assisted Imaging Combined with 3D Printing Technology: a Quality Improvement Study

Background: The extramedullary locking plate system was the common internal fixation method for hip fractures. However, common plates were poorly matched to femur, which was because they were designed based on anatomical parameters of the Western populations. Therefore, the aim was to design an end-structure of the anatomical proximal femoral locking plate that closely matched the anatomy of the Chinese population. Materials and methods: From January 2010 to December 2021, consecutive patients aged 18 years and older who underwent a full-length computed tomography scan of the femur were included. The end-structure (male and female model) of the anatomical proximal femoral locking plate was designed based on anatomical parameters of femurs that were measured in three-dimensional space using computer-assisted virtual technology. The match degree between the end-structure and femur were evaluated. Inter-observer and intra-observer agreement for the evaluation of match degree was assessed. The matching evaluation based on a three-dimensional printing model was regarded as the gold standard to assess the reliability. Results: A total of 1672 patients were included, with 701 men and 971 women. Significant differences were seen between male and female for all parameters of the proximal femur (all P<0.001). All match degree of end-structure was over 90%. Inter-observer and intra-observer agreement was almost perfect (all kappa value, >0.81). The sensitivity, specificity, and percentage of correct interpretation of matching evaluation in the computer-assisted virtual model was all greater than 95%. From femur reconstruction to completion of internal fixation matching, the process takes about 3 min. Moreover, reconstruction, measurement, and matching were all completed in one system. Conclusions: The results showed that based on the larger sample of femoral anatomical parameters, a highly matching end-structure of anatomical proximal femoral locking plate for Chinese population could be designed with use of computer-assisted imaging technology.