Correlation Analysis Of Risk Factors For Dislocation After Total Hip Arthroplasty

Objective: To analyze the risk factors of dislocation after total hip arthroplasty(THA)by comparative study and logistic regressive analysis of two groups of patients with dislocation or not after total hip arthroplasty(THA).It provides a reference for the control and clinical prevention of total hip arthroplasty dislocation.Methods: A retrospective study was conducted on the cases of total hip arthroplasty discharged from the first affiliated Hospital of Dalian Medical University from January 2003 to December 2018.the patients who were discharged from the Department of Joint surgery,the first affiliated Hospital of Dalian Medical University,underwent total hip arthroplasty.Fifty-three of 1225 patients with undislocated hip arthroplasty were randomly selected as the control group.There were 18 males and 35 females,ranging in age from 35 to 84 years(mean age 62 years).Eighteen cases of dislocation diagnosed by X-ray after THA were used as the dislocate group,including 8 males and 10 females,aged 42-80 years(mean age 68 years).The variables of the selected cases were standardized controlled.Using the image archiving and communication system(PACS)integrated into our hospital,the bilateral off-set and abduction angle of the above 71 patients were measured on X-ray image,and the medical records were consulted to find the patient's past medical history and operative records.The effects of age,history of hip surgery,absolute value of femoral head size and off-set,sex and dislocation after hip arthroplasty were analyzed.The variable factors of the selected cases were standardized controlled.A total of 18 of 1225 patients with THA were diagnosed as postoperative dislocation by X-ray,the dislocation rate was 1.4%.There were 14 cases of first dislocation within 6 weeks after operation,1 case of first dislocation at 12 weeks after operation,1 case of first dislocation at 36 weeks after operation,and 2 cases of dislocation occurred 1 year after THA.There was 1 case of anterior dislocation and the rest were posterior dislocation.Closed manual reduction was performed in 16 cases and open reduction was performed in 2 cases under intravenous anesthesia.Orthopedic shoes were fixed in abduction neutral position after operation.There were 5 patients with recurrent dislocation after reduction.Results: All patients were followed up for at least 3 months.The average abduction angle was 39.37 ±6.54 in the dislocate group and 34.88 ±7.34 in the control group.There was significant difference between the two groups(P= 0.02).The average age of the patients in the dislocate group was(62 ±10)years old,and that in the control group was(68 ±11)years old.There was significant difference between the two groups(P= 0.033).There was significant difference in the history of hip surgery by chi-square test(P = 0.014).There was significant difference in the size of femoral head between d=28mm and d ? 32 by chi-square test(P = 0.00).There was significant difference in eccentricity between the two groups by T test(P = 0.00).There was no significant difference between the two groups in chi-square test(P = 0.425).It is a risk factor for dislocation after hip arthroplasty.Conclusion: Age,femoral head diameter less than 32 mm,femoral offset,large cup abduction angle,the history of previous hip surgery these five factors are risk factors for postoperative dislocation of THA.The gender factor is a non-risk factor.Skilled surgical procedures,selection of matched prostheses,correcting eccentricity,proper prosthesis position,accurate preoperative measurements,and enhanced perioperative teaching can help reduce the incidence of postoperative dislocation of THA.