Metal–Metal Reactivity: Houston, We Have a Problem!

Abstract

In this single-surgeon series, both resurfaced hips in 1 woman and a total hip arthroplasty in another were revised for symptomatic pseudotumor (3 of 588 hips; 0.51% overall incidence; 2.2% in women). All 3 hips had 50-mm acetabular components. There was no difference in mean lateral opening angle (mean 38.7° vs 42.8° for the others) but these 3 hips all had increased acetabular anteversion (mean 27.1° vs 16.4° for the others; P<.05). Increased combined anteversion is a mechanical common denominator in pseudotumor formation. Female sex and small component size are variables associated with congenital dysplasia, which typically has a small, shallow socket and high combined anteversion. Thus, native anatomy may predispose to the joint mechanics that lead to pseudotumor formation, and not sex or size. The aggregate results indicate that the determination of satisfactory component position includes (1) assessment of the acetabular component lateral opening, (2) acetabular component version, and (3) femoral version. A mechanical problem suggests a mechanical solution. To insure capture of the femoral head by the socket and the intended bearing tribology, acetabular lateral opening angles should be <50°, assuming a femoral neck-shaft angle of 130° to 135°. Combined anteversion should not exceed 40°. In resurfacing of dysplastic cases where the neck-shaft angle exceeds 140°, the acetabular lateral opening angle needs to be correspondingly lower to achieve equivalent head capture and bearing contact.

Metal-on-Metal Total Hip Arthroplasty: Causes and High Incidence of Early Failure

“…In terms of metal sensitivity or adverse metal reactions as the primary diagnosis for failure, 4 of 5 patients in the current study who exhibited an adverse metal reaction were women, coinciding with observations in other studies. [11][12][13][14][15] This occurred in 6.5% of the current patient patients who underwent revision. Furthermore, localized soft tissue changes, whether in the setting of metal sensitivity alone or in concert with other failure reasons, were seen in 13% of patients, the majority of whom were women (7/10).…”

No adverse effects of submelt-annealed highly crosslinked polyethylene in cemented cups

“…Highly crosslinked PE appears to be a good alternative to hard-on-hard bearings, considering that metal-on-metal articulations may cause excessive wear and pseudotumors, and that ALVAL ( Carothers et al 2010 , Schmalzried and Tiberi 2010 ) and ceramic-on-ceramic articulations have been plagued by squeaking ( Sexton et al 2011 ).…”

Normalization of chromium and cobalt values after femoral head replacement

“…Mokka et al [11] showed a higher rate of ARMD in bigger diameter heads. Various authors [12–14] have suggested a higher rate of ARMD in incorrect acetabular cup placement, in anteversion, or related to greater inclination in the acetabular lateral opening angle. These studies highlight that increased friction in head-cup contact increases the risk of metallosis.…”