title: Estimation of musculotendon kinematics under controlled tendon indentation.
abstract: The effects of tendon indentation on musculotendon unit mechanics have been left largely unexplored. Tendon indentation is however routinely used in the tendon reflex exam to diagnose the state of reflex pathways. Because muscle mechanoreceptors are sensitive to mechanical changes of the musculotendon unit, this gap in knowledge could potentially impact our understanding of these neurological exams. Accordingly, we have used ultrasound (US) imaging to compare the effects of tendon indentation with the effects angular rotation of the elbow in six neurologically intact individuals. We used sagittal ultrasound movies of the biceps brachii to compare length changes induced by each of these perturbations. Length changes were quantified using a pixel-tracking protocol. Our results show that a 20mm indentation of the distal tendon is broadly equivalent to a 15° elbow rotation. We also show that within the imaging window the strain differences between the two stretching protocols are statistically insignificant. Finally, we show that there exists a significant linear relationship between the two stretching techniques and that this relationship spans a large rotational angle to indentation depth. We have used a novel tendon probe to administer controlled tendon indentations as a way to characterize musculotendon kinematics. Using this probe, we confirm that tendon indentation can be physiologically equated with joint rotation, and can thus be used as an input for muscle stretching protocols. Furthermore, this is potentially a simpler and more practical alternative to externally imposed angular joint motion.
authors: Department of Biomedical Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL, USA. Electronic address: m-chardon@northwestern.edu.
authors: Matthieu K
authors: MK
authors: Chardon
authors: Department of Biomedical Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL, USA; Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA; Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
authors: Yasin Y
authors: YY
authors: Dhaher
authors: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
authors: Nina I
authors: NI
authors: Suresh
authors: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
authors: Giselle
authors: G
authors: Jaramillo
authors: Department of Biomedical Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL, USA; Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA; Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
authors: W Zev
authors: WZ
authors: Rymer
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology; D001696:Biomechanical Phenomena; D004551:Elbow Joint / Q000502:physiology; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology; D011187:Posture; D012026:Reflex, Stretch; D013710:Tendons / Q000502:physiology
keywords: Joint rotation; Kinematics; Musculotendon unit; Skeletal muscle stretch; Tendon indentation