OBJECTIVETo explore the therapeutic effects of Xiaozhong Zhitong mixture preventing heterotopic ossification (HO) after total hip arthroplasty.

METHODSFrom July 2006 to October 2009, 154 patients underwent total hip replacement surgery were randomly divided into sham group (group A, 50 cases), indomethacin group (group B, 55 cases) and Xiaozhong Zhitong mixture group (group C, 49 cases). Among 154 patients, 9 cases were primary osteoarthris, 34 cases osteoarthritis secondary to acetabular dysplasia, 98 cases osteoarthritis secondary to avascular necrosis of the femoral head, 2 cases rheumatoid arthritis, 5 cases femoral neck fracture, 6 cases other diseases. Modified Gibson approach was used during the operation. After operation, group A was no preventing treatment, group B was treated by indomethacin 50 mg every time, twice a day; group C was treated by Xiaozhong Zhitong mixture 50 ml every time, twice a day for 4 weeks. Eighteen months after operation was study termination point and X-ray (including the double hip anteroposterior,obturator oblique and iliac oblique film) was used to observe whether heterotopic ossification was formed (Brooker classification was used to evaluate ossification degree); Harris scoring was used to evaluate the function of hip joint,including PAHSS 80 scores and IAHSS 20 scores.

RESULTSAll the patients were followed up,with the average of duration of 21.2 months. The condition of heterotopic ossification: for group A,there were 27 cases with heterotopic ossification(54%) ,and Brooker I in 8 cases, II in 9 cases, III in 8 cases and IVin 2 cases; for group B, there were 12 cases heterotopic ossification (21.82%), and Brooker I in 10 cases, II in 2 cases; for group C, there were 11 cases heterotopic ossification(22.45%), and Brooker I in 9 cases, I in 2 cases. There was significant difference among three group in heterotopic ossification by rank test (P<0.05), but no difference between group B and C (P>0.05); there were no significant difference among three groups before treatment in Harris, PAHSS and IAHSS by analysis of variance (one-way ANOVA) (P>0.05), and has significant difference at 18 months after treatment (P<0.01). There were significant difference in Harris, PAHSS and IAHSS before and after treatment at 18 months (P<0.01). LSD-t was used to analyzed the scoring of Harris, PAHSS and IAHSS, there was significant difference among group A and group B and group C (P>0.05), but no difference between group B and C (P<0.01). There were gastrointestinal reaction in 5 of group A, 35 in group B and 4 in group C.

CONCLUSIONThe effect of Xiaozhong Zhitong mixture on the prevention of heterotopic ossification after total hip arthroplasty is similar to indomethacin, but Xiaozhong Zhitong mixture has the advantages of less side effects and easily acceptance by patients.