Alterations in articular cartilage T2 star relaxation time following mechanical disorders: in vivo canine supraspinatus tendon resection models

Abstract

Background: The role of altered joint mechanics on cartilage degeneration in in vivo models has not been studied successfully due to a lack of pre-injury information. We aimed 1) to develop an accurate in vivo canine model to measure the changes in joint loading and T2 star (T2*) relaxation time before and after unilateral supraspinatus tendon resections, and 2) to find the relationship between regional variations in articular cartilage loading patterns and T2* relaxation time distributions. Methods: Rigid markers were implanted in the scapula and humerus of tested dogs. The movement of the shoulder bones were measured by a motion tracking system during normal gaits. In vivo cartilage contact strain was measured by aligning 3D shoulder models with the motion tracking data. Articular cartilage T2* relaxation times were measured by quantitative MRI scans. Articular cartilage contact strain and T2* relaxation time were compared in the shoulders before and 3 months after the supraspinatus tendon resections. Results: Excellent accuracy and reproducibility were found in our in vivo contact strain measurements with less than 1% errors. Changes in articular cartilage contact strain exhibited similar patterns with the changes in the T2* relaxation time after resection surgeries. Regional changes in the articular cartilage T2* relaxation time exhibited positive correlations with regional contact strain variations 3 months after the supraspinatus resection surgeries. Conclusion: This is the first study to measure in vivo articular cartilage contact strains with high accuracy and reproducibility. Positive correlations between contact strain and T2* relaxation time suggest that the articular cartilage extracellular matrix may responds to mechanical changes in local areas.

Qualitative and Quantitative Evaluation of Morpho-Metabolic Changes in Bone Cartilage Complex of Knee Joint in Osteoarthritis Using Simultaneous 18F-NaF PET/MRI—A Pilot Study

“…In the instance of T2* relaxometry, our findings are consistent with Lee et al findings; in their study also they also found that larger T2* values corresponded to increased cartilage degradation in a canine model. 26 However, in a research by Mankin et al, T2* values declined as cartilage deterioration progressed. 27 …”

Multiscale Correlations between Joint and Tissue-Specific Biomechanics and Anatomy in Postmortem Ovine Stifles

“…Magnetic resonance imaging (MRI) is a widely used technique to image knee anatomy [11], and quantitative relaxometry is sensitive to tissue composition including changes in water content, proteoglycans, and collagen fiber orientation [12]. Both transverse relaxation time ( T 2 ) and effective T 2 ( T 2 * ) have been shown to correlate to cartilage degeneration [13]. An increase in the T 2 correlates with damage to articular cartilage, signifying deterioration of the collagen network and increase in the water content [14].…”

Age and Sex Comparison of the Canine Supraspinatus Tendon Using Quantitative Magnetic Resonance Imaging T2 Mapping

“…1 Transection of the supraspinatus tendon can lead to increased adduction and lateral shoulder subluxation without substantial abduction, as well as changes in articular cartilage contact strain that are associated with corresponding changes in the T2* relaxation time. 2 As dogs disproportionately transfer more body weight to the thoracic limb musculature, trauma to the supraspinatus is of interest, in that injury may be anticipated to cause substantial lameness. However, identifying supraspinatus injury of the muscle or tendon has been a diagnostic challenge in veterinary medicine, as early imaging for most lameness had been limited to radiographs.…”