Aseptic loosening

Implant loosening invariably leads to clinical failure for a variety of reasons, which includes peri-prosthetic fracture of the implant or the bone adjacent to the implant. Numerous failure mechanisms limit the long-term success of endo-prosthetic implants including aseptic osteolysis, aseptic loosening, infection and implant instability (Holt et al., 2007). The key molecules of the host response at the protein level are chemokines, cytokines, nitric oxide metabolites and metallo-proteinases (Gallo et al., 2014). Aseptic osteolysis and subsequent implant failure occur because of a chronic inflammatory response to implant-derived wear particles. Despite many advances related to materials selection, and operation tool and techniques, aseptic osteolysis continues to limit implant longevity. 

Y. Abu-Amer, I. Darwech, J.C. Qohisy, Aseptic loosening of total joint replacements mechanisms underlying osteolysis and potential therapies. Arthritis Res. Ther. 9 (2007) S6. 

Wear of UHMWPE is cmrently recognized as the primary culprit responsible for aseptic loosening and late revision of hip replacements. Researchers have estimated that for each day of patient activity, around 100 million microscopic UHMWPE wear particles are released into the tissues surrounding the... 

Harris W.H. 1991. Aseptic loosening in total hip arthroplasty secondary to osteol5 is induced by wear debris from titanium-alloy modular femoral heads. J Bone Joint Surg 73 470-472. 

Despite its successful track record, wear and damage of the UHMWPE insert compromises the longevity of knee arthroplasty. Osteolysis, a rare occurrence with all-UHMWPE tibial components, has been documented with increasing frequency in modular knee replacements. Clearly, improved wear behavior of the UHMWPE insert would be advantageous from the perspective of reducing the risk of osteolysis and aseptic loosening. 

Campbell, P. (1995) On aseptic loosening of total hip replacements The role of UHMWPE wear particles. PhD Dissertation, Biomaterials/Handicap Research, Goteborg University, Goteborg, Sweden, pp. 1-225. 

Gotell P, Axelson O, Lindelof B (1972) Field studies on human styrene exposure. Work Environ Health 9 76-83 Haddad FS, Cobb AG, Bentley G, Levell NJ, Dowd PM (1996) Hypersensitivity in aseptic loosening of total hip replacements. The role of constituents of bone cement. J Bone Joint Surg Br 78 546-549... 

Currently, the most common reason for the failure of artificial joint implants is aseptic loosening, which manifests itself in reappearing pain. The underlying pathogenesis is a tissue reaction to adverse effects such as mechanical instability, and the release of wear particles from the implant biomaterial Both conditions result eventually in bone resorption and the development of osteolysis. 

In cemented total joint arthroplasties, acrylic bone cement functions as the piima ry load bearing material used to transfer loads from the implant to the bone. Bone cement Is formed from an exothermic reaction of benzoyl peroxide initiator present In polymethylmethacrylate powder (PMMA) and AI,AI-dimethyl-p-tolui-dene In methylmethacrylate monomer liquid (MMA), resulting in polymerization of PMMA to form a solid cement matrix. The in vivo integrity and performance of bone cement Is necessary for longevity of orthopedic implants, because it is believed that mechanical failure of the bone cement layer can lead to aseptic loosening of the Implant [101]. 

Wear of conventional UHMWPE has historically been recognized as the primary culprit responsible for inflammatory bone loss and late revision of hip replacements. Researchers have estimated that for each day of patient activity, around 100 million microscopic UHMWPE wear particles are released into the tissues surrounding the hip joint [19]. This particulate wear debris can initiate a cascade of adverse tissue response leading to osteolysis (bone death) and ultimately aseptic loosening of the components [20-23]. The radiograph in Figure 5.3 (provided courtesy of Av Edidin, PhD, Drexel University) shows an example of an osteolytic lesion in the pelvis located superior to the historical, gamma-sterilized acetabular component... 

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