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Saturday, March 18, 2000

Excellent results in primary cementless THA

A study that evaluates the results of primary total hip arthroplasty using a nonmodular femoral component in comparison with a modular femoral component found both the S-ROM and MHP femoral components show excellent clinical results in primary cementless total hip arthroplasty, emphasizing that stem modularity is not essential in order to achieve stable fixation.

Researchers for the study, presented in scientific exhibit 31, said fit can be achieved using a tapered monolithic stem. Moreover, modularity can make the procedure more surgically demanding and invite problems such as third-body wear.

Beginning in November 1987, three surgeons implanted 265 modular-stemmed S-ROM components (Sivash Range of Motion; Depuy, A Johnson & Johnson Company, Warsaw, Ind.) in 216 patients and 233 monoblock-stemmed MHP (Mallory-Head Porous; Biomet, Warsaw, Ind.) components in 201 patients. All components were titanium with modular femoral heads of either chrome cobalt or ceramic. The average age of the patients was 50 years in the MHP group and 46 years in the S-ROM group. Fifty-nine percent of the MHP patients and 58 percent of the S-ROM patients were males. Average height and weight, and distribution of preoperative diagnoses and Charnley class were also similar in both groups.

A variety of acetabular components were utilized and were not analyzed in this study. Time lapse for the operative procedure averaged 49 minutes ( 14) in the MHP group and 67 minutes (24) in the S-ROM group (p<0.0001). Blood loss averaged 265 cc ( 106) in the MHP group and 299 cc ( 150) in the S-ROM group (p=0.004). Roentgenographs were analyzed for any unusual bone reactive phenomena.

Clinical follow-up averaged 62 months for the S-ROM group and 57 months for the MHP group. Harris Hip Scores improved by an average of 45 points in the MHP group and 47 points in the S-ROM group. Operative time for the S-ROM group averaged 18 minutes longer than for the MHP group. Four femoral components in the S-ROM group (1.5 percent) have been revised due to aseptic loosening, and a pattern of osteolysis extending from the level of neck resection into the greater trochanter was seen radiographically in 12 percent of cases. No femoral osteolysis was seen in the MHP group.

The researchers, all of Joint Implant Surgeons, Inc., Columbus, Ohio, are Joanne B. Adams, BFA; Adolph V. Lombardi Jr., MD; Thomas H. Mallory, MD; and Durgadas P. Sakalkale, MD.

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2000 Academy News March 18 Index B

Last modified 06/March/2000 by IS