Topographic deformation patterns of knee cartilage after exercises with high knee flexion: an in vivo 3D MRI study using voxel-based analysis at 3T.

OBJECTIVES: To implement a novel voxel-based technique to identify statistically significant local cartilage deformation and analyze in-vivo topographic knee cartilage deformation patterns using a voxel-based thickness map approach for high-flexion postures. METHODS: Sagittal 3T 3D-T1w-FLASH-WE-sequences of 10 healthy knees were acquired before and immediately after loading (kneeling/squatting/heel sitting/knee bends). After cartilage segmentation, 3D-reconstruction and 3D-registration, colour-coded deformation maps were generated by voxel-based subtraction of loaded from unloaded datasets to visualize cartilage thickness changes in all knee compartments. RESULTS: Compression areas were found bifocal at the peripheral medial/caudolateral patella, both posterior femoral condyles and both anterior/central tibiae. Local cartilage thickening were found adjacent to the compression areas. Significant local strain ranged from +13 to -15 %. Changes were most pronounced after squatting, least after knee bends. Shape and location of deformation areas varied slightly with the loading paradigm, but followed a similar pattern consistent between different individuals. CONCLUSIONS: Voxel-based deformation maps identify individual in-vivo load-specific and posture-associated strain distribution in the articular cartilage. The data facilitate understanding individual knee loading properties and contribute to improve biomechanical 3 models. They lay a base to investigate the relationship between cartilage degeneration patterns in common osteoarthritis and areas at risk of cartilage wear due to mechanical loading in work-related activities. KEY POINTS: • 3D MRI helps differentiate true knee-cartilage deformation from random measurement error • 3D MRI maps depict in vivo topographic distribution of cartilage deformation after loading • 3D MRI maps depict in vivo intensity of cartilage deformation after loading • Locating cartilage contact areas might aid differentiating common and work-related osteoarthritis.

Physical workloads of the upper-extremity among workers of the Colombian flower industry.

BACKGROUND: We report the prevalence of symptoms of common upper-limb disorders and describe comprehensively mechanical workloads in a sample of workers of the Colombian flower industry. METHODS: One hundred fifty eight workers from eight flower manufacturers were assessed. Assessments included Borg self-reported exertion and working practices, medical examinations, video-based observations and kinematic and surface muscular activity assessments of upper-limb. RESULTS: Point prevalence of signs and symptoms of CTS, epicondylitis, and De Quervain's disease was 32.9%, 15.2%, and 13.3%, respectively. All tasks are executed on average in wrist extension, ulnar deviation, and high elbow flexion. Average median muscle activity across tasks ranged between 3.6% and 27.3%. Forearm muscles were mainly active. CONCLUSIONS: The occurrence of signs and symptoms of upper-extremity musculoskeletal disorders was high among the sample. The classification and cutting task showed the highest mechanical demands. Interventions in this working population are required and should be directed to allow for muscular rest on regular basis.