In Vitro Manual Therapy and Biorobotic Simulation of Glenohumeral Joint Mobilization Techniques
Physical therapists (PT) employ mobilization techniques for restoring range of motion to joints. Few studies have attempted to quantify the biomechanics of manual therapy on the glenohumeral (GH) joint. The objectives of this study were to develop an in vitro protocol to determine the biomechanical effects of joint mobilization on the GH joint, and to then simulate these mobilizations in the University of Tennessee Health Science Center (UTHSC) Joint Implant Biomechanics Laboratory’s Robotic Testing Platform (RTP). The GH joint is an incredibly shallow socket joint. This gives the joint an unusually large range of motion (ROM) compared to other ball joints. The increased ROM makes the joint unstable and susceptible to injury. The joint is completely surrounded by many muscles for support. The primary stabilizers are the rotator cuff (RC) muscles: subscapularis, supraspinatus, infraspinatus, and teres minor. These muscles were chosen to be simulated for the experiments. The objective of this study was to develop a protocol for quantifying and comparing GH joint mobilization techniques performed by physical therapists in a human cadaveric model. Two different GH joint positions were investigated using grade IV non-oscillatory mobilizations. Force data was captured using a six (DOF) load cell; three dimensional (3D) positional data was captured using a camera system with light emitting diodes (LEDs). Most notable differences between joint position and therapists occurred during posterior glide mobilization. In addition to studying other GH mobilization techniques the protocol can be used to determine structural tissue properties and/or measure effects of shoulder injuries on GH biomechanics. A separate robotic protocol was developed to simulate anterior, posterior, and inferior glides on the GH joint in neutral position. Tests were conducted through 10° flexion and 10° extension in neutral rotation, 30° internal rotation, and 30° external rotation. External rotation was found to be the stiffest joint configuration in all glide positions; neutral rotation configuration was found to be the least stiff. Two protocols were successfully developed: one for capturing PT’s technique in manual therapy, another for simulating PT’s manual therapy via a robotic testing platform. Future work can be aimed at expanding the ROM these present protocols study. Additionally, the manual articulation model can be developed into a training tool after gathering in vivo human data from additional experiments using a gait lab. The stated model could then be used to teach therapists particular techniques necessary for clinical treatment.
Biomechanics, Glenohumeral, Mobilization, Robot, Shoulder, Simulation, Analytical, Diagnostic and Therapeutic Techniques and Equipment, Medicine and Health Sciences, Physical Therapy, Rehabilitation and Therapy, Therapeutics
University of Tennessee Health Science Center
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