The compared study about femoral stem alignment with or without the special curve rasp during DAA total hip arthroplasty

Abstract

Abstract Objective To investigate whether the application of a curved rasp on the femoral side is effective in reducing the incidence of stem valgus-varus in total hip replacement with direct anterior approach (DA-THA), followed by the analysis of the independent risk factors affecting stem alignment. Methods Retrospective analysis was carried out covering 160 patients undergoing DA-THA from January 2019 to December 2021, with Tri-lock (BPS) stem applied in all 120 patients were screened according to inclusion and exclusion criteria. The data of gender, age, body mass index, FAR ratio, pelvic morphology ratio, femoral stem placement angle, use of curved rasp, intraoperative complications, WOMAC scores, were analyzed to explore the independent factors influencing the valgus-varus of the femoral prosthesis implantation. Then data of patients were divided into group A and group B according to whether the curved rasp was taken during the operation. The chi-square test was performed to compare the incidence of femoral malalignment between the two groups. Results There revealed two independent risk factors: BMI and FAR score that affected femoral stem alignment. The increased BMI was associated with a higher probability of stem malalignment (p < 0.05), FAR score < 1, with 44.00% of stem malalignment. Further analysis of subgroups revealed a 27.5% incidence of stem malalignment in patients with intraoperative application of curved rasp, the incidence of stem malalignment was significantly increased to 48.8% without curved rasp (p = 0.02). All prosthesis placement angles in group A were more illustrious than group B, especially in the statistically significant differences moderate (9.10%)/severe (8.30%) valgus and varus (p < 0.05). There found no significant difference in intraoperative complications and last follow-up assessment of WOMAC scores between the two groups of patients. Conclusions In DA-THA, BMI and FAR act as the independent risk factors for femoral stem malalignment.Intraoperative use of an curved rasp significantly reduces the incidence of malalignment of the femoral stem.