Sander Brinkhof1, Martijn Froeling2, Rob P A Janssen3,4,5, Keita Ito5,6, Dennis W J Klomp2. 1. Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. s.brinkhof@umcutrecht.nl. 2. Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. 3. Department of Orthopaedic Surgery and Trauma, Maxima Medisch Centrum, Eindhoven, The Netherlands. 4. Fontys University of Applied Sciences, Eindhoven, The Netherlands. 5. Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. 6. Department of Orthopaedics, University Medical Center Utrecht, Utrecht, The Netherlands.
Abstract
OBJECTIVE: Sodium concentration is responsible for (at least part of) the stiffness of articular cartilage due to the osmotic pressure it generates. Therefore, we hypothesized that we could use sodium MRI to approximate the stiffness of cartilage to assess early cartilage degeneration. METHODS: Four human tibial plateaus were retrieved from patients undergoing total knee replacement (TKR), and their cartilage stiffness mapped with indentation testing, after which samples were scanned in a 7 T MRI to determine sodium concentration. The relation of biomechanical parameters to MRI sodium and glycosaminoglycan (GAG) concentration was explored by a linear mixed model. RESULTS: Weak correlations of GAG concentration with apparent peak modulus (p = 0.0057) and apparent equilibrium modulus (p = 0.0181) were observed and lack of correlation of GAG concentration versus MRI sodium concentration was observed. MRI sodium concentration was not correlated with apparent peak modulus, though a moderate correlation of MRI sodium concentration with permeability was shown (p = 0.0014). DISCUSSION AND CONCLUSION: Although there was correlation between GAG concentration and cartilage stiffness, this was not similar with sodium concentration as measured by MRI. Thus, if the correlation between MRI sodium imaging and GAG concentration could be resolved, this strategy for assessing cartilage functional quality still holds promise.
OBJECTIVE:Sodium concentration is responsible for (at least part of) the stiffness of articular cartilage due to the osmotic pressure it generates. Therefore, we hypothesized that we could use sodium MRI to approximate the stiffness of cartilage to assess early cartilage degeneration. METHODS: Four human tibial plateaus were retrieved from patients undergoing total knee replacement (TKR), and their cartilage stiffness mapped with indentation testing, after which samples were scanned in a 7 T MRI to determine sodium concentration. The relation of biomechanical parameters to MRI sodium and glycosaminoglycan (GAG) concentration was explored by a linear mixed model. RESULTS: Weak correlations of GAG concentration with apparent peak modulus (p = 0.0057) and apparent equilibrium modulus (p = 0.0181) were observed and lack of correlation of GAG concentration versus MRI sodium concentration was observed. MRI sodium concentration was not correlated with apparent peak modulus, though a moderate correlation of MRI sodium concentration with permeability was shown (p = 0.0014). DISCUSSION AND CONCLUSION: Although there was correlation between GAG concentration and cartilage stiffness, this was not similar with sodium concentration as measured by MRI. Thus, if the correlation between MRI sodium imaging and GAG concentration could be resolved, this strategy for assessing cartilage functional quality still holds promise.
Authors: Andrew J Wheaton; Arijitt Borthakur; Erik M Shapiro; Ravinder R Regatte; Sarma V S Akella; J Bruce Kneeland; Ravinder Reddy Journal: Radiology Date: 2004-06 Impact factor: 11.105
Authors: Stig Heir; Tor K Nerhus; Jan H Røtterud; Sverre Løken; Arne Ekeland; Lars Engebretsen; Asbjørn Arøen Journal: Am J Sports Med Date: 2009-12-30 Impact factor: 6.202