At the LK&N we assess Motion and the interaction between the Brain and the Musculoskeletal system to study several disorders of the musculoskeletal system. Our mission is to improve care of the Subacromial Pain Syndrome, Rotator Cuff tears, and neuromuscular disorders due to Stroke, Cerebral Palsy and Obstetric Brachial Plexus Lesions through identification of etiological sub-groups.
Pain and dysfunction of the musculoskeletal system have severe impact on an individual’s quality-of-life, ability to perform daily activities and societal participation. Musculoskeletal disorders occur frequently and symptoms commonly become chronic. Adequate treatment for these symptoms becomes even more important as the society ages and the prevalence of musculoskeletal disorders increases. We aim to explore the aetiology of musculoskeletal disorders through both biomechanical as well as clinical experiments and analysis, resulting in identification of patient sub-groups for targeted treatment.
To achieve this, we collaborate with partners at the Delft University of Technology and apply innovative techniques to measure upper extremity Motion (kinematics) and the interaction between the Brain and the Musculoskeletal system (Neuromechanics).
- Ageing and Proprioception “Ageing and Proprioception in the asymptomatic shoulder: an observational cohort with reliability assessment.”
- PARTItrial “Central pain sensitisation or (peri)articular damage: the origin of pain in SAPS. A randomised, placebo controlled, blinded, cross-over trial”
- SUBSTANTIAL cohort “The role of the subscapularis in massive rotator cuff tears: a prospective cohort with biomechanical and clinical assessments.”
- TesLaRCT “Teres Major versus Latissimus Dorsi tendon transfer in posterosuperior RC Tears: a randomised controlled trial”
To obtain 3D kinematical data of the shoulder's Range-of-Motion; including external rotation in abduction and adduction, abduction, adduction, internal rotation, lateral elevation and forward flexion we use electromagnetic, camera based and kinect based (Technology in Motion laboratory) tracking devices. These kinematic data are also applied to calculate an individuals’ muscle contribution to the concerning motion using the inverse kinematics Delft Shoulder and Elbow Model (DSEM). The DSEM was developed with participation of the LK&N and is a large-scale musculoskeletal model, with which muscle and joint reaction forces can be estimated.
Figure 1| A visual representation of real-time feedback during kinematic upper extremity assessment with an electromagnetic 3D-motion tracking device (Flock of Birds).
Electromyography and force recording
At the LK&N, we use electromyography (EMG) to study muscle activation patterns including activation of arm adductors during abduction. In order to compare EMG over muscles, subjects, and time and increase reliability, we normalize EMG to the maximal activation over two isometric but antagonist tasks,resulting in an activation ratio (AR). This concept previously showed to be sensitive for patients with RClesions and patients with SAPS. Furthermore, we determine the principal action (PA) to identify the direction in which the (EMG of the) muscle is most active.
Figure 2 | One of two available EMG-measurement set-up at the LK&N to obtain the activation ratio (AR). Subjects are in standing position with the target arm in external rotation at the side. The arm is attached to a 1-dimensional force transducer at the wrist. In this setup, subjects perform EMG-recorded isometric abduction and adduction force tasks to obtain activation patterns of several shoulder muscles.
|Name:||J.H. de Groot, ir., PhD|
|Senior researcher, Associate prof.|
|Address:||Leids Universitair Medical Center|
|Department of Rehabilitation|
|2333 ZA Leiden, The Netherlands|
|Telephone:||+31 (0)71-526 3447|
|Name:||C.L. Overbeek, MD|
|Adress:||Leids Universitair Medical Center|
|Department of Orthopedics|
|2333 ZA Leiden, The Netherlands|
|Telephone:||+31 (0)71-526 2581|