Glycolytic reprogramming underlies immune cell activation by polyethylene wear particles.

Primary total joint arthroplasties (TJAs) are widely and successfully applied reconstructive procedures to treat end-stage arthritis. Nearly 50 % of TJAs are now performed in young patients, posing a new challenge: performing TJAs which last a lifetime. The urgency is justified because subsequent TJAs are costlier and fraught with higher complication rates, not to mention the toll taken on patients and their families. Polyethylene particles, generated by wear at joint articulations, drive aseptic loosening by inciting insidious inflammation associated with surrounding bone loss. Down modulating polyethylene particle-induced inflammation enhances integration of implants to bone (osseointegration), preventing loosening. A promising immunomodulation strategy could leverage immune cell metabolism, however, the role of immunometabolism in polyethylene particle-induced inflammation is unknown. Our findings reveal that immune cells exposed to sterile or contaminated polyethylene particles show fundamentally altered metabolism, resulting in glycolytic reprogramming. Inhibiting glycolysis controlled inflammation, inducing a pro-regenerative phenotype that could enhance osseointegration.

Diagnostic guidelines for the histological particle algorithm in the periprosthetic neo-synovial tissue.

BACKGROUND: The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination. METHODS: The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles. RESULTS: All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis. CONCLUSIONS: The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies.

Periprosthetic Mass after Total Hip Replacement / 대한고관절학회지

PURPOSE: To analyze the characteristics and causes of periprosthetic huge mass which occur after treatment by total hip arthroplasty. MATERIALS AND METHODS: Of the patients who had undergone total hip arthroplasty from January 2000 to October 2007, we retrospectively evaluated the 10 patients who suffered huge soft tissue mass. Five of these patients had received metal-on-metal bearing (group 1) prostheses, and the other 5 had received metal-on-polyethylene bearings (group 2). We evaluated the size and location of the mass, the extent of osteolysis, and the hematologic and pathologic examination results. RESULTS: Roentgenographically, the location of the masses varied from the acetabular area to the distal femoral stem. The mean mass diameter of all 10 patients was 14.6 cm(7-21 cm)x6.2 cm(3-9 cm)x7.2 cm(4-12 cm). Osteolytic lesions were found in 3 group 1 patients and 3 patients in group 2. High counts of lymphocytes and eosinophils were present in group 1. High counts of macrophages were present in group 2. CONCLUSION: The occurrence of osteolysis and huge soft mass after total hip arthroplasty is thought to be related to foreign body reaction by polyethylene wear particles and metal hypersensitivity. Outside-in patterned cortical thinning was considered to be indicative of a long standing periprosthetic soft tissue mass effect.