The purpose of this study was to review our intermediate-term experience with posterior fracture-dislocations of the hip. We evaluated the accuracy of the Pipkin and Brumback classification schemes as predictors of outcome, assessed the importance of certain treatment variables, and determined the complication rates of this injury in a group of 33 patients followed for an average of 49 months. The overall results were 67% good, 18% fair, and 15% poor, with no excellent results. The Pipkin classification scheme was a useful predictor of outcome because patients with less severe Pipkin 1 or 2 injuries had statistically significant better outcomes than did those who sustained Pipkin 3 or 4 injuries (p < 0.02). Due to a large number of subgroups, we could not demonstrate the usefulness of the Brumback classification system as a predictor of outcome. There were no statistically significant differences in outcome or complication rates when comparing time with hip reduction, definitive operative intervention, or anatomic operative approach to injury. Our study represents the second largest report on posterior dislocation of the hip associated with femoral head fracture. Although outcome of the patients in our series is not outstanding, the 67% good results represent a significant improvement over all previous reports with large numbers of patients. We demonstrate significant improvement in prognosis when treatment goals for these injuries include anatomic reduction, restoration of hip joint stability, and removal of all interposed bone fragments.

26:353-358, 1972)

Cross-sectional studies have demonstrated significant decreases in bone mass in femoral cortical bone adjacent to prostheses. Thirty-six patients who had undergone 31 cemented and 9 uncemented primary total hip arthroplasties (THA) were prospectively studied to define further the natural history of this femoral cortical bone loss. Dual-energy X-ray absorptiometry (DXA) was employed to quantify bone mineral density (BMD) changes in four subregions around the femoral prostheses. Femoral BMD loss (average 12.3%) was observed in the three proximal subregions 2 months postoperatively. This loss increased to 21.2% by 6 months postoperatively, and by 2 years postoperatively it averaged 25.5% in the same three subregions. There were no significant BMD changes in the subregion distal to the prosthesis tip or in the contralateral hip. Subgroups were compared based on prosthesis size and cement use. Statistically significant differences in BMD loss were observed between the large cemented cobalt chrome prosthesis group (n = 8) and the large uncemented titanium prosthesis group (n = 8). These differences were only present in the most proximal medial subregion where the large cemented groups had twice the bone loss in this area as compared with the large uncemented group. The data indicate that bone loss occurs adjacent to femoral prosthesis within 2 months of surgery and that DXA is a useful technique to quantify prospectively femoral cortical bone loss following THA.

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Bone mineral density (BMD) is a predictor of fracture risk. The purpose of this study was to determine whether a correlation exists between femoral neck BMD and an indicator of mechanical bone strength in human and bovine samples. Human proximal femurs were obtained from seven men and two women undergoing total hip arthroplasty (THA), mean age 60.3 years. Preoperative BMD measurements of the femoral neck were obtained (Lunar DPX). A 3 cm2 area of interest on each excised femoral neck corresponding to the preoperative BMD measurement site was carefully marked and BMD was remeasured postoperatively. Ten excised bovine femoral necks were also measured for BMD. A bicortical core, each cortex 2.8 cm2 in area, containing the center of the area of interest was removed from the human and bovine femoral necks, cut into multiple 7-mm thick, multiple cross-sectional discs, and measured for hardness by indent depth (Rockwell International Hardness Tester, Wilson Mechanical Instruments, New York, NY). In vivo human femoral neck BMD measurements correlated with in vitro BMD measurements (r = 0.99). BMD measurements of human femoral necks were significantly lower than BMD measurements of bovine femoral necks (P < 0.05). Inverse relationships were found between in vivo and in vitro human BMD measurements and indent depth (r = -0.58 and -0.59, respectively). Bovine BMD measurements and indent depth were also inversely related (r = -0.64).(ABSTRACT TRUNCATED AT 250 WORDS)