title: Deformational behaviour of knee cartilage and changes in serum cartilage oligomeric matrix protein (COMP) after running and drop landing.
abstract: OBJECTIVE
  To investigate (1) the effect of running and drop landing interventions on knee cartilage deformation and serum cartilage oligomeric matrix protein (COMP) concentration and (2) if the changes in cartilage volume correlate with the changes in serum COMP level.
  
  
  METHODS
  Knee joint cartilage volume and thickness were determined using magnetic resonance imaging (MRI) as well as COMP concentration from serum samples before and after in vivo loading of 14 healthy adults (seven male and seven female). Participants performed different loading interventions of 30 min duration on three different days: (1) 100 vertical drop landings from a 73 cm high platform, (2) running at a velocity of 2.2m/s (3.96 km), and (3) resting on a chair. Blood samples were taken immediately before, immediately after and 0.5h, 1h, 2h and 3h post intervention. Pre- and post-loading coronal and axial gradient echo MR images with fat suppression were used to determine the patellar, tibial and femoral cartilage deformation.
  
  
  RESULTS
  Serum COMP levels increased immediately after the running (+30.7%, pre: 7.3U/l, 95% confidence interval (CI): 5.6, 8.9, post: 9.1U/l, 95% CI: 7.2, 11.0, P=0.001) and after drop landing intervention (+32.3%, pre: 6.8U/l, 95% CI: 5.3, 8.4; post: 8.9U/l, 95% CI: 6.8, 10.9, P=0.001). Cartilage deformation was more pronounced after running compared to drop landing intervention, with being significant (volume: P=0.002 and thickness: P=0.001) only in the lateral tibia. We found a significant correlation (r(2)=0.599, P=0.001) between changes in serum COMP (%) and in cartilage volume (%) after the drop landing intervention, but not after running.
  
  
  CONCLUSIONS
  In vivo exercise interventions differentially regulate serum COMP concentrations and knee cartilage deformations. The relation between changes in COMP and in cartilage volume seems to depend on both mechanical and biochemical factors.
authors: Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Am Sportpark Müngersdorf 6, Cologne, Germany. niehoff@dshs-koeln.de
authors: A
authors: A
authors: Niehoff
authors: M
authors: M
authors: Müller
authors: L
authors: L
authors: Brüggemann
authors: T
authors: T
authors: Savage
authors: F
authors: F
authors: Zaucke
authors: F
authors: F
authors: Eckstein
authors: U
authors: U
authors: Müller-Lung
authors: G-P
authors: GP
authors: Brüggemann