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Background: Revision hip arthroplasty is associated with a dislocation rate that is three to five times greater than the rate following primary hip replacement. Conversion of a hip hemiarthroplasty to a total hip replacement is a revision arthroplasty, but it differs from revisions of total hip arthroplasties because a native acetabulum is replaced and the subsequent prosthetic femoral head is smaller. It was our purpose to determine whether the risk of dislocation following conversion surgery is the same as or greater than that following revision total hip replacement. Methods: From 1994 to 2005, eighty-nine hemiarthroplasties were converted to a total hip arthroplasty in seventy- seven patients, and the results were compared with those of 115 first-time revision total hip replacements following a primary total hip replacement in 111 patients. A retrospective chart review was performed, and radiographic measurements were obtained. The patient demographics were similar between the two groups. The percentages of patients who had undergone revision of only the acetabular component as compared with both components as well as the percentages of those who had received a modular femoral stem as compared with a nonmodular stem were also similar between the two groups. Results: Postoperatively, the femoral head size and the positioning of the acetabular component were similar between the two groups. The acetabular components were significantly larger (p < 0.001) in the group in which a total hip arthroplasty had been revised because they required additional acetabular reaming for placement of a new component. There were significantly more dislocations after the conversion procedures (22%) than after the revisions of the total hip arthroplasties (10%) (p < 0.018). Within both groups, the size of the acetabular component, the intraoperative range of motion, and the positioning of the acetabular component were similar between the hips that dislocated and those that did not. However, smaller femoral head components were at greater risk for dislocation after conversion surgery than after revision of a total hip arthroplasty. Conclusions: A substantial reduction of the size of the prosthetic femoral head is unique to conversion arthroplasty and appears to play a role in instability after the revision surgery. While the smallest heads dislocated in the conversion group, a larger femoral head did not ensure stability. The increased dislocation risk with conversion surgery requires emphasis on soft-tissue balance and avoidance of excessive downsizing of the femoral head in an attempt to maximize hip stability. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Background: Management of periprosthetic femoral fractures is often complex, and few studies have documented its associated mortality. Methods: We retrospectively identified from our trauma and surgical registries 106 patients who underwent surgery for a periprosthetic femoral fracture. We then identified a contemporaneous age and sex-matched control cohort of 309 patients who had a hip fracture (femoral neck or intertrochanteric) and 311 patients who underwent primary hip or knee replacement. Mortality at one year was identified with use of the Social Security database. Results: Twelve (11%) of 106 patients died within one year following surgical treatment of a periprosthetic fracture. During the same follow-up period, fifty-one (16.5%) of 309 patients died following surgery for a hip fracture and nine (2.9%) of 311 patients died following primary joint replacement. The mortality rate after a periprosthetic femoral fracture was significantly higher (p < 0.0001) compared with that for matched patients who had undergone primary joint replacement, and it was similar to the mortality rate after a hip fracture. For periprosthetic fractures, a delay of greater than two days from admission to the time of surgery was associated with an increased mortality rate at one year (p < 0.0007). Forty-nine patients underwent revision arthroplasty for the treatment of a Vancouver type-B periprosthetic fracture, and six (12%) died. In contrast, twenty-four patients with a Vancouver type-B periprosthetic fracture were treated with open reduction and internal fixation and eight (33%) died. The difference was significant (p < 0.03). Conclusions: The mortality rate within one year following surgical treatment of periprosthetic femoral fractures is high and is similar to that after treatment for hip fractures. Because revision arthroplasty for the treatment of type- B periprosthetic fractures was associated with a one-year mortality rate that was significantly less than that after surgical treatment with open reduction and internal fixation, in instances when either treatment option is feasible, revision arthroplasty may be the preferred option. [ABSTRACT FROM AUTHOR]

Abstract: Due to the uneven and often inadequate quality of cross-table lateral hip radiographs, many radiographic studies of femoral head penetration into polyethylene in total hip arthroplasty are limited to the two-dimensional measurement of femoral head penetration using the A/P film only. We postulated that the use of two oblique frontal projections at 90° to each other would improve the three-dimensional evaluation. Using an established hip phantom, the idealized accuracy and precision of the three-dimensional Martell method was evaluated, contrasting the standard A/P and cross-table lateral projections versus a pair of oblique projections by four independent readers. Accuracy and precision resulting from the use of two oblique projections (average accuracy ±63μm, precision ±26μm) were similar to that obtained using the conventional A/P and cross-table lateral views (accuracy ±54μm, precision ±22μm), though the results of the two oblique views were slightly more variable. These observations suggest that by using two oblique A/P projections, the major disadvantage of using the cross-table lateral films, namely the variable quality of the images, is avoided. Perhaps, therefore, the utility and availability of three-dimensional data in comparable clinical studies may be improved. [Copyright &y& Elsevier]