Migration of polyethylene debris along well‐fixed cemented implants

Abstract

Implants, consisting of smooth Inox cylinders, were cemented into the lower femur and upper tibia of nine sheep to study the distal migration of polyethylene particles. Some implants had a titanium-bead porous coat at the proximal end. These were of three types: In the first type, the porous coat was covered with hydroxyapatite to obtain a bony seal; the second type was prepared for a polymethylmethacrylate seal; in the third type, the porous zone was surrounded by a 2-mm-thick space to allow the formation of a fibrous seal. Small polyethylene particles were injected into the knees once a week during the third and fourth months after implantation. The animals were euthanized 2 months later. Major longitudinal sections of the implants and the surrounding bone were examined under a polarized light microscope. Birefringent particles were counted at the cement-bone and cement-implant interfaces. Osteolysis was not observed. None of the seals significantly decreased the migration of particles around the cemented part of the implants. Particles were observed in cement fissures and vacuoles. They migrated at both interfaces and in the bone itself. They were visible in marrow spaces between bone trabeculae.

Peri-Implant Distribution of Polyethylene Debris in Postmortem-Retrieved Knee Arthroplasties: Can Polyethylene Debris Explain Loss of Cement-Bone Interlock in Successful Total Knee Arthroplasties?

“…We examined regions at the interface between PMMA cement and bone, and distal (>5 mm) to the interface (Figure 3). As has been reported by other groups [10, 12, 14, 23], the morphology of these particles included filaments and lenticular shapes, which were visible as individual particles or in clumps (Figure 4A–C). Due to the thickness of the sections, particles that appeared smaller or rounder may have been oriented out of plane.…”

“…In comparison to our study, Massin et al [12] examined postmortem retrieved THA femoral components, using polarized light microscopy to identify PE wear debris at both the metal-cement and cement-bone interfaces. They too found birefringent debris within marrow-filled trabecular structures adjacent to the implant, and additionally demonstrated a “reservoir” of debris distal to the component, but remarked on the lack of published material demonstrating distal osteolysis in THA.…”

“…Previous studies have identified PE wear debris in the knee or hip through various methods, whether through polarized light microscopy of intact tissue [12, 13, 25, 27] or through tissue digestion protocols [14, 18, 23, 28–32]. The approach taken in the current study was unique in that the goal was to examine native, unprocessed PE debris in close proximity to an intact cement-bone interface of non-revised knees.…”

Experimental micromechanics of the cement–bone interface

“…Massin and colleagues 29 showed that polyethylene particles can migrate around nonloosened cemented femoral components to the distal end of the mantle and suggested that they progress through porosity in cancellous bone. Particles might also move along the interface, aided by fluid motion upon loading.…”

Orthopedic Implant Retrieval and Failure Analysis

“…The fluid may contain wear debris from the articulating surfaces which become lodged in this space and is associated with osteolysis [124]. There is evidence from histological analysis of retrieved implants that the cancellous bone may be part of the effective joint space despite a well-fixed implant [247,248]. Polyethylene has also been observed in the most proximal regions of cemented hips in the bone-cement interface [25].…”