Development of a support system for total hip arthroplasty: evaluation of lower limb loads using virtual and dummy human body models

Abstract Purpose The direct anterior approach (DAA) is one of the procedures used for total hip arthroplasty (THA) and offers advantages such as faster postoperative recovery. A lower limb traction operating table has been developed to assist in intraoperative movement and retention of the lower limb. However, these movements depend on the experience of individual surgeons, and no quantitative safety index is currently available. The authors are developing a surgical support system for THA that evaluates lower limb loads to achieve safe and reliable surgery. This study aimed to establish a system using dummy and virtual human body models that can quantitatively evaluate lower limb loads during procedures. Methods The dummy human body model consisted of a skeletal specimen with six silicone tubes mimicking four types of muscles. Tension sensors were installed to measure tension forces. A virtual human body model with 40 muscles, along with the operating table model, was constructed using the musculoskeletal simulation software OpenSim. The movements of the operating table and the dummy human body model were measured using a 3D motion analysis system, and identical movements were applied for simulation. Results Traction and extension movements showed that the trend of reaction forces in the traction direction and the relative magnitudes of muscle tension forces in the dummy model were consistent with the simulation results. In addition, the simulation enabled evaluation of muscle forces not physically represented in the dummy model. Conclusion The validity of the simulation was verified by comparing measured and simulated forces applied to both the virtual and dummy human body models. The combined use of these models enabled evaluation of loads on the sole and muscles surrounding the hip joint. This approach enables quantitative and comprehensive biomechanical evaluation of intraoperative procedures and contributes to the development of a safe surgical support system.