Influence of total hip arthroplasty on sagittal lumbar-pelvic balance: Evaluation of radiographic parameters

Objective To prospectively analyze the radiographic variables of lumbosacral sagittal balance in the pre- and postoperative period of patients submitted to total hip arthroplasty (THA). Methods A prospective, observational, comparative study that evaluated pre- and postoperative radiographic parameters of 71 patients, submitted to 72 total hip arthroplasties in a 3-year period (2014–2017) for primary coxarthrosis, of whom 28 performed late postoperative control (6 months) through the Surgimap Spine software (Surgimap, New York, NY, USA). Statistical analysis was performed using the Student t-test, the analysis of covariance (ANCOVA) model, and the Kolmogorov-Smirnov test. The data were analyzed using the IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp., Armonk, NY, USA). A p-value < 0.05 indicated statistical significance. Results A total of 72 cases, presenting a mean age of 57.9 years old, predominantly females (60.6%) and patients > 50 years old (71.8%). There was an overall decrease in lumbar lordosis values in the immediate postoperative period, without major global changes in late evolution. It was found that patients with a pelvic incidence ≥ 60° tended to have their other sagittal balance parameters elevated. Conclusion There was no significant difference between the radiographic variables of sagittal lumbopelvic balance in the evaluated periods. Lumbar lordosis and pelvic incidence were the main modifying factors. Improvement of low back pain after THA, without changes in parameters, suggests different pathology mechanisms still to be clarified.