title: Soft tissue knee injury with concomitant osteochondral fracture is associated with higher degree of acute joint inflammation.
abstract: BACKGROUND
  Osteochondral fractures are often seen on magnetic resonance imaging (MRI) of acutely injured knees, but their existence has gained little interest because of a lack of knowledge of their relation to treatment options and outcome. It is not clear whether acute phase synovial fluid (SF) concentrations of cartilage and bone markers and proinflammatory cytokines are different between traumatically injured knees with or without osteochondral fracture.
  
  
  OBJECTIVE
  Acutely injured knees with an osteochondral fracture, particularly fractures with disrupted cortical bone, have higher concentrations of bone markers and cytokines than do knees without an osteochondral fracture.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  Synovial fluid (hemarthrosis) was aspirated (median 1 day after injury) and 1.5-T MRI was performed (median 8 days after injury) in the acutely injured knee of 98 individuals (26% women; mean age, 23 years). As visualized on MRI, 39% knees had an osteochondral fracture with disrupted cortical bone, 30% had an osteochondral fracture with intact cortical bone, and 32% did not have an osteochondral fracture. Concentrations of sulfated glycosaminoglycan, ARGS aggrecan, cartilage oligomeric matrix protein, osteocalcin, secreted protein acidic and rich in cysteine (SPARC), osteopontin and proinflammatory cytokines (interleukin [IL]-1β, IL-6, IL-8, and tumor necrosis factor [TNF]-α) were analyzed.
  
  
  RESULTS
  After adjusting for days between injury and SF aspiration, age at injury, and sex, knees with any osteochondral fracture (with or without disrupted cortical bone) had significantly higher SF concentrations of TNF-α (median [interquartile range (IQR)] = 9 [7-12] pg/mL vs. 7 [5-14] pg/mL; P = .013), whereas knees with an osteochondral fracture with disrupted cortical bone had significantly higher SF concentrations (medians [IQRs]) of SPARC (492 [328-754] ng/mL vs. 407 [140-685] ng/mL; P = .030), IL-8 (278 [148-628] pg/mL vs. 138 [67-413] pg/mL; P = .028), and TNF-α (11 [7-15] pg/mL vs. 7 [5-14] pg/mL; P = .004) compared with knees without an osteochondral fracture.
  
  
  CONCLUSIONS
  In acutely injured knees with hemarthrosis, a concomitant osteochondral fracture with disrupted cortical bone is associated with a higher degree of joint inflammation.
authors.affiliation: Per Swärd, Department of Orthopaedics, Lund University, BMC C12, SE-221 84 Lund, Sweden. per.sward@med.lu.se.
authors.forename: Per
authors.initials: P
authors.lastname: Swärd
authors.forename: André
authors.initials: A
authors.lastname: Struglics
authors.forename: Martin
authors.initials: M
authors.lastname: Englund
authors.forename: Harald P
authors.initials: HP
authors.lastname: Roos
authors.forename: Richard B
authors.initials: RB
authors.lastname: Frobell
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D001168:Arthritis / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D064236:Cartilage Oligomeric Matrix Protein / Q000378:metabolism; D002358:Cartilage, Articular / Q000293:injuries; D003430:Cross-Sectional Studies; D005260:Female; D050723:Fractures, Bone / Q000150:complications* / Q000175:diagnosis; D050724:Fractures, Cartilage / Q000150:complications* / Q000175:diagnosis; D006395:Hemarthrosis / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D007718:Knee Injuries / Q000150:complications* / Q000175:diagnosis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015676:Osteonectin / Q000378:metabolism; D031222:Patellar Dislocation / Q000150:complications / Q000175:diagnosis; D016119:Posterior Cruciate Ligament / Q000293:injuries; D017695:Soft Tissue Injuries / Q000150:complications* / Q000175:diagnosis; D013396:Suction; D013582:Synovial Fluid / Q000378:metabolism*; D000070600:Tibial Meniscus Injuries; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D055815:Young Adult
chemical_list: D015415:Biomarkers; D064236:Cartilage Oligomeric Matrix Protein; D016209:Interleukin-8; D015676:Osteonectin; C577241:SPARC protein, human; D014409:Tumor Necrosis Factor-alpha
keywords: anterior cruciate ligament; biomarkers; bone; cartilage; osteoarthritis; posttraumatic