A retrospective study of patients who had had a primary total hip arthroplasty without cement between 1983 and 1990 was done to examine differences in clinical and radiographic results between obese and normal- weight individuals. Patients were considered to be of normal weight if the body-mass index (calculated as weight in kilograms divided by height in meters squared) was between twenty and less than thirty, and they were considered to be obese if the body-mass index was thirty or more. There were 127 normal-weight patients (142 hips) and fifty-five obese patients (sixty hips) in the analysis. Eight obese patients (eight hips) who had a body-mass index of forty or more were considered to be morbidity obese and were examined separately as a subset of the obese group. The duration of follow- up averaged forty-eight months (range, twenty-four to ninety-two months). There were no differences between the groups with regard to age, diagnosis, the type of stem or cup, the type of bone, the postoperative level of activity, or the duration of follow-up. The obese patients had a significantly greater loss of blood during the operation than the patients in the normal-weight group. There were no significant differences between groups with regard to the prevalence of perioperative complications, the number of units of blood transfused, the operative duration, or the duration of hospitalization. Of the 202 hips, 184 (91 per cent) were pain-free or only mildly painful at the latest follow-up examination. The normal-weight and non-morbidly obese groups had a significant (p < 0.001) increase in each of the functional measures compared with the preoperative status. The eight morbidly obese patients had a smaller, yet significant (between p = 0.01 and p = 0.05), increase in most functional measures. The total rate of mechanical failure of the femoral components was 6 per cent (six revisions for aseptic loosening and two components that were loose radiographically) in the normal- weight group compared with 2 per cent (one revision for aseptic loosening and no components that were loose radiographically) in the non-morbidity obese group (p = 0.28). The total rate of failure of the acetabular components was 7 per cent (seven revisions and three components that were loose radiographically) in the normal-weight group and 8 per cent (three revisions and two components that were loose radiographically) in the non-morbidly obese group (p = 0.82). There were no failures of a cup or stem in the morbidity obese patients. The obese patients in this series did not have a higher rate of complications, with the exception of an increased intraoperative loss of blood. They had similar gains in relief of pain and functional abilities and no difference in the rate of mechanical failure compared with the normal-weight patients. On the basis of these results, after an average duration of follow-up of four years, it appears that obese patients can benefit substantially from primary total hip arthroplasty without cement and that obesity does not markedly increase operative risk. However, substantial differences might occur with long-term follow-up.
ASJC Scopus subject areas
- Orthopedics and Sports Medicine