title: Osteoclastogenesis-related cytokines and peri-prosthetic osteolysis in revision metal-on-metal total hip replacements.
abstract: OBJECTIVE
  Peri-prosthetic osteolysis is a major cause for revision hip arthroplasty; various cytokines including those in the osteoclastogenesis pathway have been identified as potentially key in the osteolysis process. Adverse reactions to metal debris in metal-on-metal total hip replacements have led to an increase in revision procedures. This study examines the levels of osteoclastogenesis-related cytokines in serum and synovial fluid samples obtained from patients at the time of revision metal-on-metal total hip replacement and compares between patients with and without radiographic evidence of peri-prosthetic osteolysis.
  
  
  METHODS
  Sandwich ELISA techniques were used to detect IL-6, IL-18, M-CSF, sRANKL and OPG in the samples. Results were analysed with linear regression, Fisher's tests and t-tests; p<0.05 considered significant. Samples from 36 patients (18 with osteolysis, 18 without osteolysis) were analysed.
  
  
  RESULTS
  There was wide variation in the detectable levels of cytokines. No significant differences were found between patients with and without osteolysis in mean synovial fluid levels of IL-6 (p = 0.863), IL-18 (p = 0.324), M-CSF (p = 0.508), sRANKL (p = 0.884), OPG (p = 0.776) or mean serum levels of OPG (p = 0.993) or sRANKL (p = 0.565) (insufficient detection of IL-6, IL-18 or M-CSF in serum samples). A correlation was found between synovial fluid levels of IL-6 and OPG in patients without osteolysis (r2 = 0.618, p<0.001) but not with osteolysis (r2 = 0.0004).
  
  
  CONCLUSIONS
  These results indicate that the process of peri-prosthetic osteolysis is complex and multifactorial; there may also be an influence of metallosis. Further research is needed to increase understanding of peri-prosthetic osteolysis and influence clinical practice.
authors.affiliation: 1 Department of Trauma and Orthopaedics, University Hospital Wales, Cardiff - UK.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Eastwood
authors.forename: Alun
authors.initials: A
authors.lastname: John
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Jones
authors.forename: Helen
authors.initials: H
authors.lastname: Hodgson
authors.forename: Deborah
authors.initials: D
authors.lastname: Mason
authors.forename: Rachel
authors.initials: R
authors.lastname: Waddington
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Wei
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D016207:Cytokines / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008875:Middle Aged; D010010:Osteoclasts / Q000378:metabolism*; D010012:Osteogenesis / Q000502:physiology*; D010014:Osteolysis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000378:metabolism; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D013582:Synovial Fluid / Q000378:metabolism*
chemical_list: D016207:Cytokines