The Comparative Study Of Two Radiographic Methods To Measure Acetabular Prostheses Inclination And Analysis And Prevention Of Prosthesis Dislocation After Total Hip Arthroplasty

Purpose: There are two radiographic methods to measure acetabular prostheses inclination after total hip arthroplasty: X-ray radiogrammetry and computed tomography(CT)measurement.Two measurement methods will be compared and observed to find out the differences between each other.In the meantime,We studied the preoperative and postoperative imaging of the prosthesis dislocation after total hip arthroplasty in patients and analyzed the reasons of postoperative prosthesis dislocation,summarized the prevention measures.Methods: A retrospective analysis of 815 patients with total hip arthroplasty was performed in our hospital,and 87 patients were found to have both anteroposterior view of the pelvis and double hip joint CT,and we compared the measurements of acetabular prostheses inclination in X-ray image with the measurements of acetabular prostheses inclination in CT image to analyze the differences between the two methods.In total hip arthroplasty with 815 case,29 cases occur postoperative prosthesis dislocation.We measured the data of acetabular prostheses anteversion and acetabular prostheses inclination on the postoperative anteroposterior view of the pelvis and the preoperative and postoperative pelvic positivities of femoral offset and the change of limb length to investigate the causes of postoperative dislocation.Results:1.We measured the acetabular prostheses inclination in the anteroposterior view of the pelvis and double hip joint CT of 87 cases and find that the mean of the measurements by X-ray was(49.39±7.27)degree,the mean of the measurements by CT was(49.05±7.51)degree,and acetabular prostheses inclination in X-ray measurement and CT measurement has no statistical differences(P=0.112>0.05).2.In X-ray measurement,only 60.92% cases were included in the acetabular safety area(30-50)degrees put forward by Lewinnek.3.Among 815 patients got total hip arthroplasty,29 cases suffered prosthesis dislocation and dislocation rates 3.56%.4.29 patients with dislocation were aged between 40-78 years of age,the average age of 63.One case in the range of 31-40 years old,two cases in the range of 41-50 years old,four cases in 51-60 years old,twelve cases in 61-70 years old,ten cases in 71-80 years old,and zero cases over 80 years old.Ten cases were more than 70 years old in all patients with dislocation,accounting for 34.48%.We can analysis found that old age is a risk factor for postoperative dislocation.5.In 27 patients with no obvious cause of dislocation four indicators(acetabular prostheses inclination,acetabular prostheses anteversion,femoral offset changing value and limb length changing value),among them one indicators was abnormal in two cases,accounting for 7.41%.There were seventeen cases in the two abnormal indicators,accounting for 62.96%.Among the three abnormal indicators,eight cases were abnormal,accounting for 29.63%.There were zero cases of the four abnormal indicators.We can analyze two or more of the abnormal indicators after total hip arthroplasty are more prone to postoperative dislocation.6.One case of dislocation caused by trauma,and one case of dislocation caused by poor postoperative compliance in patients with four indicators(acetabular prostheses inclination,acetabular prostheses anteversion,femoral offset changing value and limb length changing value)had no obvious abnormalities.Conclusion: Acetabular prostheses inclination in X-ray measurement and CT measurement has no statistical differences.Old age is a risk factor for postoperative dislocation.In the four indicators of acetabular prostheses inclination,acetabular prostheses anteversion,femoral offset changing value and limb length changing value,two or more of the abnormal indicators after total hip arthroplasty are more prone to postoperative dislocation.Poor postoperative compliance and trauma is a risk factor for dislocation after total hip replacement.