Development of an Active Finger Motion Simulator: With In-Vitro Assessments of Tendon Loads and Joint Kinematics

Musculoskeletal injuries of the finger far outnumber those of other joints, and while in-vitro motion simulators are useful for studying joint biomechanics and evaluating surgical repairs, considerably less simulator development has been reported for the finger compared to other joints. Replication of active musculoskeletal movement during in-vitro testing has been shown to be more representative of in-vivo motion patterns, and closed-loop motion controllers are the current state-of-the-art for in-vitro kinematics studies. However, an in-vitro motion simulator with closed-loop tendon load control and simultaneous tendon excursion control has not yet been reported for the finger. This thesis outlines the design and development of an active motion simulator for the study of finger joint kinematics, as well as forces and excursions of the flexor/extensor tendons. Performance of the system was verified in terms of tendon load control accuracy and motion repeatability, before conducting two cadaveric studies. An in-vitro study on the effects of wrist position and distal extensor tendon rupture verified that the new simulator produced expected finger kinematics and tendon loads. With the new simulator validated, its high sensitivity in measuring tendon loads was leveraged to observe the effects of A2 and A4 pulley excision and subsequent surgical repair. The thesis culminates with a summary of sample size analysis and statistical effect sizes that will aid future in-vitro finger studies with this simulator