Femoral alignment of the Charnley stem: a randomized trial comparing the original with the new instrumentation in 123 hips.

Deficient cement mantles are associated with aseptic loosening of the stem component of total hip replacement. In a former study of 206 Charnley stems, we found high frequencies of stem malalignment, especially on the lateral view, consequently resulting in a high percentage of low cement mantle grading. If the "true" lateral radiographic projection is not used, there is a risk that the frequency of mantle defects is underestimated. A logistic regression analysis showed a high correlation between low cement mantle grading and stem loosening after a mean follow-up of 10 years. The new Charnley instrumentation was introduced in 1994 and we started a randomized trial including 123 prostheses to determine whether the new instrumentation improved the position of the stem in both the AP and lateral planes. Postoperative radiographs revealed a significant change in AP positioning-i.e., from a high percentage of varus with the original method to valgus with the new instrumentation. However, there was no difference on the lateral view, with a persisting high frequency of stems with implant-inner cortex contact resulting in high percentages of low cement-mantle grading in both systems. If this deficiency, in a long-term perspective, is associated with aseptic loosening, as many authors have claimed, the manufacturers should address the problem.

Outcome after total hip arthroplasty: Part II. Disease-specific follow-up and the Swedish National Total Hip Arthroplasty Register.

The Swedish National Total Hip Arthroplasty Register records primary hip replacements, revisions and surgical technique/environmental factors. The end-point for failure is revision. A prosthesis still in place, however, does not mean success. Clinical and radiographic outcomes should describe in more detail the efficacy of hip replacement surgery instead of the relatively blunt outcome measure that the register can provide. We performed a clinical outcome analysis on patients with primary total hip replacement thus testing the adequacy of the end-point for failure in the Swedish register. 1,113 randomly selected patients who had had total hip replacement surgery between 1986 and 1995 answered a disease-specific self-administered questionnaire (WOMAC). A cohort of 344 patients was studied, using the Harris Hip Score and a conventional radiographic examination as outcome measures. We found clinical failure rates of 13% and 20% for all implants after 10 years, using 60 points or revision as the definition of failure in the Harris Hip Score and WOMAC, respectively. The result, according to the register during the same period, was a 7% revision rate. The clinical failure rate depended on the type of evaluation tool, definition of failure and demographics, which made it difficult to decide whether there was a need for revision. With the exception of pain measured by the Harris Hip Score, the results showed no significant correlation between clinical failure and radiographic failure. Hence, with the knowledge that there is a difference between the revision rate according to the register and clinical outcome, the strict definition of failure in the register is useful as an end-point for primary hip replacement surgery.

The Charnley versus the Spectron hip prosthesis: radiographic evaluation of a randomized, prospective study of 2 different hip implants.

A total of 410 hips were randomized to treatment with either a Charnley (206 hips) or a Spectron (204 hips) total hip arthroplasty. The patients were operated on by a standardized procedure using a contemporary cementing technique and were followed after 1, 3, 5 to 6, and 10 years. The postoperative radiographs showed a significantly increased rate of malalignment and consequently low grade of cement mantle quality of the Charnley stem compared to the Spectron. No differences concerning cement mantle quality or positioning were found between the Charnley ogee cup and the metal-backed Spectron. Evaluation of the follow-up radiographs revealed 10 loose Charnley stems and 1 loose Spectron stem and 4 loose Charnley ogee cups and 23 loose Spectron metal-backed cups. The differences of revision rate for the femoral and acetabular components of the 2 prostheses were significant (P = .03, Charnley femoral component more frequent; P = .03, Spectron acetabular component more frequent). The radiographic evaluation strengthened this disparity. Poor wear characteristics of the metal-backed Spectron cup are perhaps the main reason for the highly significant difference in mechanical failure rate between the 2 cups. We therefore propose that metal-backing of cemented cups should be avoided, at least when combined with larger femoral heads. The difficulty in positioning the Charnley stem with an adequate cement mantle, especially in the absence of trochanteric osteotomy, might explain the inferior Charnley stem longevity in this study.

Screening for breast cancer with mammography in Bohuslän County, Sweden.

The unique organization of breast cancer screening in Bohuslän, using a specially designed mammography bus, has allowed women from a relatively large area to be screened for breast cancer. The cooperation with radiologists and surgeons at the central hospitals in the county is very positive and interesting. As can be appreciated, this is a very streamlined and efficient operation. So far, we have arrived at the same results as pilot investigations in other counties.