Evaluating the Changes in Sagittal Balance via EOS Imaging before and after Total Hip Arthroplasty

Abstract

Background and Aim: Sagittal imbalance is often presented as one of the major problems in individuals suffering from orthopedic pain, particularly those affected by destructive hip joint osteoarthritis. In this regard, total hip arthroplasty (THA) as a therapeutic procedure for such patients has resulted in the restoration of sagittal balance. Therefore, the present study aimed to evaluate the changes in sagittal balance using EOS imaging before and after THA and also reflect on its effect on hip joint function, knee pain, and disability percentage due to low back pain (LBP). Methods: Utilizing a prospective cohort study, a total number of 24 patients suffering from extreme unilateral hip osteoarthritis and in need of unilateral THA were selected based on the inclusion and exclusion criteria, and then, sagittal balance parameters, including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), sacrofemoral angle (SFA), sacrofemoral distance (SFD), lumbar lordosis (LL), and stem angle (SA) were investigated after performing standing radiographs by means of the EOS device. One year after THA, all the above-mentioned parameters were also measured by EOS imaging before and after the surgery and the patients completed some questionnaires, which is the Oswestry Low Back Pain Disability Index (OLBPDI) to evaluate disability percentage resulting in LBP, the Knee Injury and Osteoarthritis Outcome Score (KOOS) instrument to assess knee pain, and the Harris Hip Score (HHS) measure to rate hip joint function, and then the results were analyzed using the SPSS Statistics software (ver. 17). Results: The patients consisted of 13 males (54.2%) and 11 females (45.8%) with the mean age of 52.87±13.05. The mean score of the preoperative PI was also equal to 54.74±10.66 and it was 58.19±11.58 after the surgery (p=0.025). However, the mean values of other parameters at the preoperative stage did not show any significant changes. As well, hip joint function and knee pain resulting from LBP improved in the patients after the surgery (p<0.001). Conclusion: The study findings demonstrated that THA probably influenced sagittal balance through PI. Moreover, the postoperative hip joint function, knee pain, and disability percentage caused by LBP significantly enhanced compared with those before the surgery. Thus, it was concluded that the evaluation of sagittal balance parameters could help patients with orthopedic pain.