Posture stability and risk of fall test in the objective assessment of balance in patients with ectopic bone tissue after total hip replacement

Abstract

Introduction. Total hip replacement is an operative treatment method for end-stage osteoarthritis, considered the most effective nowadays. One of the typical complications after the procedure is heterotopic ossification which may influence patient posture stability and increase the risk of falls. Aim. The study aimed to assess whether patients developing heterotopic ossifications after total hip replacement have a higher risk of falls in comparison to the matched-cohort group without them. Materials and methods. 46 out of 312 patients undergoing a total hip replacement in 2020 who developed heterotopic ossifications were observed. For these patients, a propensity score based on age, sex, and BMI was generated, and a matched-cohort control group consisting of 39 patients was selected. Each patient was operated on via an anterolateral approach, and an uncemented total hip prosthesis was implanted. Patients from both cohorts underwent postoperative radiological and biomechanical assessment and fulfilled WOMA C and Oxford questionnaires pre-and postoperatively. Statistical analyses of the results were performed. Results. There were statistically significant differences between cohorts in the postural stability test (4.9±1.1 vs 2.0±1.0 p<0.05), antero-posterior stability index (3.6±1.2 vs 1.6±0.9, p<0.05), medio-lateral stability index (3.0±1.3 vs 1.0±0.7, p<0.05) and risk of fall test (9.8±1.0 vs 7.8±1.0, p<0.05). No statistically significant differences were observed in the WOMA C and Oxford questionnaires. Conclusions. Our study proved that heterotopic ossifications, which appear in hip abductor muscles, could have an impact on balance and the risk of falls in patients after total hip replacement. In the elderly population, this can result in serious consequences such as a periprosthetic fracture or head trauma after total hip replacement.