Effect of femoral head diameter on risk of dislocation after primary total hip arthroplasty / 中国矫形外科杂志

ABSTRACT

[Objective]To discuss the effect of femoral head diameter on risk of dislocation after primary total hip arthroplasty,in order to choose the reasonable diameter of femoral head for preventing the postoperative dislocation. [Methods]From March 1990 to August 2008,primary total hip arthroplasties with various head sizes were performed in 706 patients(762 hips).There were 301 males and 405 females.The average age of the 706 patients in this series were 57 years(range 21～78 years).The preoperative diagnosis for each of the patients were osteonecrosis in 203,congenital dysplasia in 129(the Crowe IV in 15),femoral neck fracture in 190,osteoarthritis in 112,rheumatoid arthritis and ankylosing spondylitis in 58 and the other diagnosis in 14.The femoral head diameter was 22mm in 220 of the procedures,26mm in 83,and 28mm in 459.Among the 762 cases,a modified Harding approach was preferred in 95%,and a posterolateral approach was preferred in 5%.Patients routinely were followed at definite intervals and were specifically queried about dislocation.[Results]All the patients were followed up for at least six months.Of the 762 cases,there were 28 dislocations;the dislocation rate was 3.7%.In the subgroups,there were 7.3%(16/220) for 22mm heads,4.8%(4/83) for 26mm heads,and 1.7%(8/459) for 28mm heads,the difference were statistically significant(x2=13.193,P=0.001;R=0.131,P=0﹤0.01).[Conclusion]The femoral head diameter has a positive effect on risk of dislocation,using a larger femoral head could reduce the risk of dislocation after total hip arthroplasty.A larger femoral head could be selected for preventing the postoperative dislocation and 22mm femoral heads should be avoided.