The Relationship Of The Anteversion Angle And Abduction Angle Of The Acetabular Prostheses With Dislocation After Total Hip Arthroplasty

Objective:To analyze the relationship of the anteversion angle and abductionangle of the Acetabular prostheses with dislocation after total hiparthroplasty. to explore appropriate angle range of the abduction angleand anteversion angle, which provides the reference for the clinicalpractice.Materials and methods:From Feb2009–Feb2015,882patients (1164hips) wereperformed with total hip arthroplasty in our hospital，Including524casesof male patients (702hips) and358female patients (462hips). Accordingto etiology classification:524patients of osteonecrosis of the FemeralHead (741hips),39cases of osteoarthritis of the hip (46hips),108casesof congenital hip dysplasia (144hips), ankylosing spondylitis in36cases(49hips). Femoral neck fractures in147cases (147hips)， the other28patients (37hips). The X-ray films of the hip were used for measuringacetabular abduction angle and anteversion angle.The study setabduction angle of30degrees-50degrees, anteversion angle5degrees-25degrees as normal. The abduction angle is divided into two groups: GroupA：30degrees-50degrees，GroupB：less than30degrees ormore50degrees, The anteversion angle is divided into two groups，GroupC： between5degrees-25degrees.GroupD： less than5degreesor more than25degrees. GroupE：the abduction angle is between30degrees-50degrees and anteversion angle is between5degrees-25degrees, GroupF：the abduction angle is less than30degrees or morethan50degrees and anteversion angle is less than5degrees or more than25degrees.The results were statistically analyzed, with a P value lessthan0.05indicating significant difference.Results:All the patients were followed up with an average of17months (range1month一60months). All patients had no prosthesisloosening and osteolysis. In882cases (1164hips), there were12cases ofdislocation, dislocation rate was1.03%.The average abduction angle ofpatients who had a dislocation was44.74°±6.53°。whereas the averageabduction angle for the other patients who did not dislocate was42.36°±5.37°. no significant statistical difference between the two groups(P>0.05). And the average anteversion angle of patients who had adislocation was11.83°±5.52°。whereas the average anteversion angle forthe patients who did not dislocate was13.38°±4.95°. No significantstatistical difference between the two groups (P>0.05). The study setabduction angle of30degrees-50degrees, anteversion angle5degrees -25degrees as normal. The anteversion angle less than5degrees or morethan25degrees,5degrees-25degrees, two different ranges of thedislocation rate had no significant difference (P＞0.05).The abductionangle less than30degrees or more the50degrees,30degrees-50degrees,two different ranges of the dislocation rate had no significant difference(P＞0.05).Conclusion:The acetabular abduction angle in the range of28.5°-58.5°andanteversion angle in the range of4.58°-26.33°had no significantcorrelation with the dislocation after total hip arthroplasty.For the surgeonwho operates more than30hips every year, Acetabular Prosthesisabduction angle and anteversion angle have no Significantlyrelationship with dislocation after total hip arthroplasty, While thePostoperative soft tissue imbalance and combined anterior angle may bethe main causes of postoperative dislocation.