The Research Of Prosthesis Position And Leg Length Discrepancy With Intraoperative Fluoroscopy In Direct Anterior Approach For Total Hip Arthroplasty In Lateral Decubitus Position

Background Direct anterior approach for total hip arthroplasty is performed through muscle space to expose the hip without excessive damage to the soft tissue around the hip,which can significantly accelerate postoperative recovery and reduce postoperative pain of patients.The classic DAA is in the supine position,requiring the use of special traction beds and special surgical instruments.The proximal femur can be fully exposed through adduction,external rotation and extreme posterior extension of the hip joint by the assistant.The operation can be performed on the common fracture bed and conventional surgical instruments in lateral decubitus position,but it is difficult to evaluate the leg length discrepancy during the operation.Controlling the leg length discrepancy is one of the principal purposes of total hip arthroplasty,and is also a common reason for patients’ dissatisfaction with the effect of the surgery.The leg length discrepancy caused by the shortening or prolongation of the affected limb after hip arthroplasty will often affect the patients’ walking gait,reduce their postoperative satisfaction and quality of life,and even cause serious complications such as pelvic tilt,hip dislocation or prosthesis loosening.The DAA-THA is an approach that performed through muscle space to expose the hip without excessive damage to the soft tissue around the hip,which can significantly accelerate postoperative recovery and reduce postoperative pain of patients.The classic DAA-THA is in the supine position,requiring the use of special traction beds and special surgical instruments,which will increase the study cost for primary hospitals.The DAA with lateral decubitus position need the assistant to move,rotate and extend the hip joint in order to expose the proximal femur,which can be performed with common fracture bed and conventional surgical instruments.However,due to the pelvic tilt with the lateral decubitus position,it is difficult to directly evaluate the lower limb length discrepancy during the operation.Solving the lower limb length discrepancy problem is one of the principal purposes of the THA,and it is also a common reason that patients are not satisfied of the surgery result.The lower limb length discrepancy problem caused by shortening or extending the length of lower limb due to the THA will often affect patient’s walking gait,which will lower their life qualities and postoperative satisfaction.In serious cases,it will cause problems such as pelvic tilt,hip dislocation or loosening of the prosthesis,and impact the final result of the operation.Objective To verify the reliability of the intraoperative fluoroscopy,which is using to confirming the position of the protheses and controlling the lower limb length during the direct anterior approach for total hip arthroplasty(DAA-THA)in lateral decubitus position,and discuss the clinical application value of the intraoperative fluoroscopy.Methods A retrospective analysis was performed on the imaging data of 100 patients(100 hips)receiving DAA-THA in lateral position from September 2017 to June 2019 in our hospital,including 50 patients in the fluoroscopy group and 50 patients in the nonfluoroscopy group.Then the patients were divided into two groups by leg length discrepancy.with leg length discrepancy no more than 10 mm were set as equal length group,and the patients with leg length discrepancy more than 10 mm were set as discrepancy group.The two groups were compared independently.During the operation,we recorded the operation time and bleeding amoun,and after the operation,we recorded the postoperative pelvic radiograph to measure and calculate the abduction angle,anteversion angle and the leg length discrepancy.We evaluated the hip Harris score and forgetten joint score after the operation.The data that conform to the normal distribution are verified by t test and expressed as mean ± standard deviation(?).Measurementdata that do not meet the normal distribution are verified using the Mann-Whitney U test and expressed as the median(quartiles P25 to P75).Results The leg length discrepancy in fluoroscopy group was 4.2 mm(0~8.0 mm),and the average leg length discrepancy in the non-fluoroscopy group was 7.5 mm(0~14 mm),P <0.05.The difference was statistically significant.The average anteversion angle of the acetabulum in the fluoroscopy was 15.5 ° ± 2.9(9.4 ~ 19.7 °),and the average abduction angle of the acetabulum was 41.2 ° ± 3.4(31.7 ~ 46.2 °).The average anteversion angle of the acetabulum in the non-fluoroscopy group was 14.6 ° ± 2.0(8.9-17.7 °)and average abduction angle of the acetabulum was 41.7 ° ± 3.6(31.4 ~ 46.3 °).There was no significant difference between the two groups.The Harris score and forgetten joint score after operation were reviewed at the same time.The differences between intraoperative fluoroscopy group and non-intraoperative fluoroscopy group were not statistically significant(P> 0.05),but the two scores of the equal length group were significantly better than the difference group,and the differences were statistically significant(P <0.05).Conclusion Intraoperative perspective has no statistical difference in the accuracy of acetabular prosthesis implantation for DAA-THA in lateral decubitus position.However,it can significantly improve the accuracy of controlling the length of the lower limbs and the hip joint center.