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.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kirurgi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Surgery (hsv//eng)

Keyword

Aged

Aged

80 and over

Arthroplasty

Replacement

Hip

instrumentation

Female

Follow-Up Studies

Hip

radiography

Humans

Male

Middle Aged

Postoperative Complications

Regression Analysis

Publication and Content Type

ref (subject category)

art (subject category)