Indian Journal of Science and Technology

Abstract

Background/Objectives: Leg Length Discrepancy (LLD) after THA is the most common cause of patient’s dissatisfaction. Hence, this paper aims at determining magnitude of LLD which is bearable by any person. Methods/Statistical analysis: It includes simulation and analysis of human musculoskeletal models in Open Sim software for various hip muscles as these muscles are more affected after THA. Firstly, muscle force results from Open Sim are cross-checked and validated with an established muscle model. Then, models of different LLDs are obtained in Open Sim and results of muscle force are plotted on graphs for various hip movements like flexion/extension, adduction/abduction, etc. Findings: LLD bearing capacity for different body weights of the person is found in the range of 2.0-2.5 cm. It is found that more is the body weight of the person; smaller is the range of his/her LLD bearing capacity and vice-versa. Through literature survey, it is found that person can bear LLD from 10-50 mm to avoid major problems like lower back pain, muscle or ligament injury, nerve palsy, etc. Different researchers found different values of LLD to avoid same problem. So, this range is quite large to define LLD bearing capacity of a person. From this study, a concise range of LLD bearing capacity was found. Application/ Improvements: Surgeon can plan his/her preoperative planning and prosthesis design in such a way that LLD will not exceed a given range after THA.
Keywords: Leg Length Discrepancy (LLD), Muscles, Muscle Force, Open Sim,Total Hip Arthroplasty (THA)