Patricia Campbell

Numerous studies have examined the histology of metal‐on‐metal hip tissues for evidence of a dose response to metal wear but have often reported inconclusive or contradictory findings. The aim of the present study was to address these discrepancies using multiple histological scoring methods to characterize the tissue features of one large group of revised metal‐on‐metal total hips. Periprosthetic tissues from 165 metal‐on‐metal hip revisions were examined for features of aseptic lymphocytic vasculitis associated lesions (ALVAL) as rated using two scoring systems as well as rankings for macrophage and lymphocyte numbers, intracellular wear debris and necrosis. Correlations between histological features and clinical variables including gender and time to revision and implant variables including articular surface wear volume or visual taper corrosion scores were examined. Both ALVAL scores reflected the macrophage dominated histology with average scores of 5.9/10 and 1.5/3. There was a statistically significant correlation between the original ALVAL score and wear rate per year (correlation coefficient = 0.17, p = .05) and a moderate correlation between the number of macrophages and wear particles and wear volume. There was no statistically significant correlation between wear and any other feature including lymphocytic inflammation or necrosis. Strong correlations between combined cup and ball wear volume and histological characteristics were not observed, although the number of macrophages was more closely correlated with wear than lymphocytes or necrosis.

Case: This was a postmortem retrieval study to assess bone fixation in a hydroxyapatite-coated ACTIS stem and a beaded Pinnacle Sector cup retrieved from an 89-year-old man 15-months postoperatively. Previous radiographic examinations showed good implant fixation without any radiolucency. The sectioned cup and stem showed good fixation on visual, microradiographic, and histological examinations. Slight changes in bone density and mineral content were observed. Conclusions: Clinical fixation was achieved in both components with variable degrees of bone ingrowth and ongrowth at 15 months postoperatively in this postmortem retrieval case.

Hip resurfacing arthroplasty (HRA) has a long clinical history and has utilized a variety of bearing material combinations with mixed clinical success. This paper reviews the local and systemic consequences of metal-on-metal hip resurfacing implants. Local tissue reactions cover a spectrum from no clinically adverse effects to adverse complications leading to revision associated with pain, osteolysis, or pseudotumor formation. Factors affecting the local tissue response to any implant include surgical, implant and patient factors. Metal particle size, shape and volume are important to the response around metal-on-metal implants. Surgical placement, particularly of the acetabular component, is important to the generation of wear debris. The number of patients with a sensitivity to the cobalt or chromium constituents of metal-on-metal implants is thought to be low and the cause and effect between patient sensitivity and implant failure is considered to be uncertain. Systemic toxicity from chronic exposure to the ions from metal-on-metal implants is still extremely rare although studies into potential cardiac or neurologic effects have suggested that subtle changes may be present that warrant continued and larger follow-up studies of longer-term cohorts.

The Application of In Situ Multi-Elemental Imaging With Laser Spectroscopy to Periprosthetic Tissue Characterization Pat Campbell1, Ahmad Al-Shi |

The case of a child is described who was treated for distal femoral osteosarcoma with chemotherapy, removal of the distal femoral bone, and the implantation of a series of distal femoral endoprostheses with hinged tibial components. The design of this modular prosthesis allows for expansion during the years that the bones continue to grow. The tissues from nine surgical procedures were examined, along with one tibial bearing and axle component. Wear debris was noted in variable amounts in nearly all of the tissues but solid corrosion products from the modular junctions were abundant only in the last revision tissues. The amount of wear and corrosion of the explants seemed inconsistent with the size and amount of corrosion products in the tissues. The source of the debris is likely to be in the modular connections that were not revised.

A peculiar type of surface pitting damage to revised joint replacement implant metal surfaces has been attributed to cellular activity and termed “inflammatory cell‐induced‐corrosion.” We visually examined 1859 explanted metal implants to document the presence and extent of these features. The data was used to examine correlations between these features and the implant material, and modularity as well as clinical variables. The features were observed in approximately 77% of modular and 30% of monobloc hip implants in a variety of metals, as well as to some degree in various other implants. To test the possibility that these features were an artefact of electrocautery damage during revision surgery, a cleaned, flat, polished, CoCr disk was exposed to a variety of electrocautery interactions. This led to the production of pits and markings comparable to the published damage and to the damage found on the explants we examined. It is concluded that electrocautery damage rather than cellular activity is the cause of these features. Although rarely reported, this damage may be associated with femoral neck fracture. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1148–1155, 2018.

The lubrication of the cartilaginous structures in human joints is provided by a fluid from a specialized layer of cells at the surface of a delicate tissue called the synovial lining. Little is known about the characteristics of the fluids produced after a joint arthroplasty procedure. A literature review was carried out to identify papers that characterized the synovial lining and the synovial fluids formed after total hip or knee arthroplasty. Five papers about synovial lining histology and six papers about the lubricating properties of the fluids were identified. The cells making up the re-formed synovial lining, as well as the lining of interface membranes, were similar to the typical Type A and B synoviocytes of normal joints. The synovial fluids around joint replacement devices were typically lower in viscosity than pre-arthroplasty fluids but the protein concentration and phospholipid concentrations tended to be comparable, suggesting that the lining tissue function was preserved after arthroplasty. The widespread, long-term success of joint arthroplasty suggests that the lubricant formed from implanted joint synovium is adequate for good clinical performance in the majority of joints. The role the fluid plays in component wear or failure is a topic for future study.