Articulating spacers used in two-stage revision of infected hip and knee prostheses abrade with time

Abstract

Background: Articulating spacers used in two-stage revision surgery of infected prostheses have the potential to abrade and subsequently induce third-body wear of the new prosthesis.

Questions/purposes: We asked whether particulate material abraded from spacers could be detected in the synovial membrane 6 weeks after implantation when the spacers were removed for the second stage of the revision.

Patients and methods: Sixteen hip spacers (cemented prosthesis stem articulating with a cement cup) and four knee spacers (customized mobile cement spacers) were explanted 6 weeks after implantation and the synovial membranes were removed at the same time. The membranes were examined by xray fluorescence spectroscopy, xray diffraction for the presence of abraded particles originating from the spacer material, and analyzed in a semiquantitative manner by inductively coupled plasma mass spectrometry. Histologic analyses also were performed.

Results: We found zirconium dioxide in substantial amounts in all samples, and in the specimens of the hip synovial lining, we detected particles that originated from the metal heads of the spacers. Histologically, zirconium oxide particles were seen in the synovial membrane of every spacer and bone cement particles in one knee and two hip spacers.

Conclusions: The observations suggest cement spacers do abrade within 6 weeks. Given the presence of abrasion debris, we recommend total synovectomy and extensive lavage during the second-stage reimplantation surgery to minimize the number of abraded particles and any retained bacteria.

Fig. 1

A radiograph shows the pelvis of a 60-year-old woman with a spacer implanted in the left hip.

Fig. 2A–B

(A) AP and (B) lateral radiographs show the left knee of a 71-year-old man with an implanted mobile spacer.

Fig. 3

An XRF spectrum of a synovial membrane sample shows the characteristic peaks of zirconium, chlorine, calcium, chromium, iron, and cobalt.

Fig. 4A–C

Histologic analysis of the synovial lining of a hip spacer from a 60-year-old man shows abrasion particles of zirconium dioxide (Stain, toluidine blue; original magnification, ×200). (A) Light microscopy shows the mulberry-shaped zirconium dioxide particles and some smaller particles (black). (B) The smaller abrasion particles (< 1.5 μm, light) from the same sample are seen better with polarized light microscopy (C) The total amount of small abrasion particles of zirconium dioxide is seen in the dark-field illumination.

Fig. 5A–B

Histologic analysis of the synovial lining of a hip spacer from a 71-year-old man shows a greater piece of cement (1.2 mm) with smooth, rounded surfaces as a sign of abrasion (Stain, toluidine blue; original magnification, ×50). (A) With light microscopy, zirconium particles of the cement are dark and (B) can be seen better as light particles with polarized light microscopy.