title: Hyaluronan concentration and size distribution in human knee synovial fluid: variations with age and cartilage degeneration.
abstract: BACKGROUND
  One potential mechanism for early superficial cartilage wear in normal joints is alteration of the lubricant content and quality of synovial fluid. The purpose of this study was to determine if the concentration and quality of the lubricant, hyaluronan, in synovial fluid: (1) was similar in left and right knees; (2) exhibited similar age-associated trends, whether collected postmortem or antemortem; and (3) varied with age and grade of joint degeneration.
  
  
  METHODS
  Human synovial fluid of donors (23-91 years) without osteoarthritis was analyzed for the concentrations of protein, hyaluronan, and hyaluronan in the molecular weight ranges of 2.5-7 MDa, 1-2.5 MDa, 0.5-1 MDa, and 0.03-0.5 MDa. Similarity of data between left and right knees was assessed by reduced major axis regression, paired t-test, and Bland-Altman analysis. The effect of antemortem versus postmortem collection on biochemical properties was assessed for age-matched samples by unpaired t-test. The relationships between age, joint grade, and each biochemical component were assessed by regression analysis.
  
  
  RESULTS
  Joint grade and the concentrations of protein, hyaluronan, and hyaluronan in the molecular weight ranges of 2.5-7 MDa, 1-2.5 MDa, and 0.5-1 MDa in human synovial fluid showed good agreement between left and right knees and were similar between age-matched patient and cadaver knee joints. There was an age-associated decrease in overall joint grade (-15 %/decade) and concentrations of hyaluronan (-10.5 %/decade), and hyaluronan in the molecular weight ranges of 2.5-7 MDa (-9.4 %/decade), 1-2.5 MDa (-11.3 %/decade), 0.5-1 MDa (-12.5 %/decade), and 0.03-0.5 MDa (-13.0 %/decade). Hyaluronan concentration and quality was more strongly associated with age than with joint grade.
  
  
  CONCLUSIONS
  The age-related increase in cartilage wear in non-osteoarthritic joints may be related to the altered hyaluronan content and quality of synovial fluid.
authors.affiliation: Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. mtemple@eng.ucsd.edu.
authors.forename: Michele M
authors.initials: MM
authors.lastname: Temple-Wong
authors.affiliation: Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. rswlx1018815@gmail.com.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Ren
authors.affiliation: Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. pquach8@gmail.com.
authors.forename: Phu
authors.initials: P
authors.lastname: Quach
authors.affiliation: Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. bradley.c.hansen@gmail.com.
authors.forename: Bradley C
authors.initials: BC
authors.lastname: Hansen
authors.affiliation: Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. albert@eng.ucsd.edu.
authors.forename: Albert C
authors.initials: AC
authors.lastname: Chen
authors.affiliation: Department of Molecular and Experimental Medicine, MEM-161, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA. hasegawa@scripps.edu.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hasegawa
authors.affiliation: Department of Molecular and Experimental Medicine, MEM-161, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA. ddlima@scripps.edu.|Shiley Center for Orthopaedic Research & Education at Scripps Clinic, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA. ddlima@scripps.edu.
authors.forename: Darryl D
authors.initials: DD
authors.lastname: D'Lima
authors.affiliation: Department of Molecular and Experimental Medicine, MEM-161, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA. koziol@scripps.edu.
authors.forename: Jim
authors.initials: J
authors.lastname: Koziol
authors.affiliation: Department of Orthopaedic Surgery, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. komasuda@ucsd.edu.
authors.forename: Koichi
authors.initials: K
authors.lastname: Masuda
authors.affiliation: Department of Molecular and Experimental Medicine, MEM-161, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA. mlotz@scripps.edu.
authors.forename: Martin K
authors.initials: MK
authors.lastname: Lotz
authors.affiliation: Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. rsah@ucsd.edu.|Department of Orthopaedic Surgery, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. rsah@ucsd.edu.|Center for Musculoskeletal Research, Institute of Engineering in Medicine, University of California-San Diego, 9500 Gilman Drive, Mail Code 0412, La Jolla, CA, 92093-0412, USA. rsah@ucsd.edu.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sah
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism* / Q000473:pathology; D002357:Cartilage Diseases / Q000378:metabolism* / Q000473:pathology; D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D006820:Hyaluronic Acid / Q000032:analysis / Q000378:metabolism*; D007719:Knee Joint / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D013582:Synovial Fluid / Q000737:chemistry / Q000378:metabolism*; D055815:Young Adult
chemical_list: D006820:Hyaluronic Acid