The 3D-Printed Customized Femoral Short Stem Offers Improved Anatomical Parameters Restoration, Fitness and Biomechanical Performance Compared With Traditional Femoral Stem

Objective: The traditional femoral stem is unsuitable for patients with severe proximal femoral bone defects or deformities. However, 3D-printed customized designs offer improved proximal femoral canal contact and enhance the initial stability of the femoral prosthesis. Therefore, this study aims to compare the anatomical parameters, contact parameters, and performance of the 3D-printed customized femoral short (CFS) stem with those of the traditional femoral stem following total hip arthroplasty (THA). Methods: An in vitro study simulating THA was performed using artificial femur models, with a 3D-printed CFS stem as the experimental group and a Trilock stem as the control group. Anatomical parameters, fitness, filling, micro-motion, and strain distribution were evaluated using artificial femoral models. Micro-motion and strain were recorded under different simulated bodyweight loading using a 3D digital image correlation measurement system. Results: The neck-shaft angles (NSA) and coronal femoral horizontal offset (CFHO) of the 3D-printed CFS stem (NSA: 125.22°, CFHO: 41.03 mm) were closer to those of the intact femur (NSA: 127.37°, CFHO: 43.27 mm) compare with the Trilock stem (NSA: 132.61°, CFHO: 32.98 mm). In addition, the 3D-printed CFS stem showed improved fitness at cross-sections (The top of the lesser trochanter: 6.31%, the middle of the lesser trochanter: 23.42%, the bottom of the lesser trochanter: 26.61%) and reduced micro-motion under different simulated bodyweight loads (1000: 0.043, 1375: 0.056, 2060 N: 0.061 mm). Conclusions: The 3D-printed CFS stem provides improved restoration of anatomical parameters, enhanced fitness, and superior biomechanical performance compared with the Trilock stem.