The pathology of total joint arthroplasty

Abstract

Although the clinical results of total joint arthroplasty are usually excellent, some implants develop loosening and require revision. Implants usually fail by a combination of mechanisms, but different basic designs tend to show different dominant mechanisms of failure. Infection causes failure of about 1-5% of cases of primary arthroplasty. Clues to the presence of infection include clinical signs, a periosteal reaction, a positive culture of aspirated joint fluid, and acute inflammation identified in tissue around the implant. There are several different mechanisms and modes of implant wear, and perhaps the most important cause of aseptic loosening is an inflammatory reaction to particles of wear debris. Abrasive, adhesive, and fatigue wear of polyethylene, metal and bone cement produces debris particles that induce bone resorption and implant loosening. Particles can cause linear, geographic, or erosive patterns of bone resorption (osteolysis), the distributions of which are influenced by the implant design. Micromotion of implants that did not achieve adequate initial fixation is another important mechanism of loosening. Fatigue failure at the bone/cement and bone/implant interface may cause aseptic loosening, and may be especially important for implants with relatively smooth surfaces. Stress shielding can influence local bone density, but is rarely an isolated cause of implant loosening. Elevated hydrodynamic pressure has been associated with bone resorption in the absence of implants, and may also play a role in implant loosening.

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

“…Wear debris of conventional UHMWPE has been associated with osteolysis and implant loosening [6,36,74]. Currently, there is no consensus on the differences in the biologic activity of the wear debris from crosslinked UHMWPE compared to conventional UHMWPE.…”

How Has the Introduction of New Bearing Surfaces Altered the Biological Reactions to Byproducts of Wear and Modularity?

“…However, genetic regulation of the response in patients and as yet unknown responses to nanoparticulates may confound this prediction. In addition, the cellular responses to highly crosslinked UHMWPE and ceramic particles, although not absent, do show some level of reduction in the provocation of inflammation and osteoclastogenesis [7,8,20,63]. The findings for the new generation of MoM bearings have not demonstrated the predicted improvement in prosthesis life expected for a low-wear, hard-on-hard bearing.…”

“…Crosstalk between macrophages and osteoclasts through inflammatory cytokines will accelerate osteoclastogenesis, leading to the potential for osteolysis and implant loosening. The precise pathways in this process have been well studied [8,26,34,78] but a number of recent papers indicate that the molecular processes involved in the response to conventional UHMWPE may be broader than originally appreciated.…”

Ipsilateral Shoulder and Elbow Arthroplasty Using Custom Interlocking Prostheses

“…It is characterized by bone remodeling according to Wolff's Law as the stressors on the bone are changed with the introduction of an implant [1]. In one study, 9% of patients had a major reduction in cortical thickness in the proximolateral region of the humeral stem after shoulder arthroplasty at an average followup of 5.3 years [10].…”