Doctoral Defense - Adam J. Chrzan

About the Event

The Department of Mechanical Engineering

Michigan State University

Ph.D. Dissertation Defense

Friday, March 28, 2025 at 11:00 AM EDT

Engineering Building Room 3405 and via Zoom

Contact Department or Advisor for Zoom Information

ABSTRACT

MULTI-DIMENSIONAL INVESTIGATIONS INTO THE BIOMECHANICS OF THE HUMAN THUMB: A FOCUS ON OSTEOARTHRITIS AND SURGERY

By: Adam Chrzan

Advisor: Dr. Tamara Reid Bush

The human thumb is necessary for the completion of daily tasks (e.g., driving, cooking), and accounts for up to 50% of overall hand function. The carpometacarpal (CMC) joint, located at the base of the thumb, has developed osteoarthritis (OA) in up to 50% of older individuals, with a marked preponderance among females. The debilitating symptoms of pain, weakness, and deformity have led to the inability to perform self-care, daily activities, and may require intensive surgery for symptom relief. However, the current clinical tools used to quantify thumb function are not able to capture the thumb’s complex and dynamic abilities, making it challenging to monitor thumb health or determine the impact of treatments and surgical intervention. This research focused on creating and implementing novel methods that were capable of quantifying the motion and force capabilities of the human thumb in three-dimensional space and creating a visual interpretation of function to facilitate clinical translation.

Coordinate systems derived from motion capture technology were used to determine the optimal mathematical method to quantify thumb metacarpal (bone at base of thumb) motion, as there is no accepted standard. The selected method was then used to determine the motion capabilities of thumb joints, including the CMC joint, in cohorts of asymptomatic control participants, and participants with CMC OA before and after surgical intervention. An innovative three-dimensional ‘thumb kinematic space’ was created and assessed to determine volumetric changes in thumb motion between test populations. Force abilities of the thumb, independent of other fingers, were measured using a novel design capable of measuring force throughout the thumb’s three-dimensional motion space. The magnitude of force generated, the location of force, and the direction of force application were determined and analyzed.

Analysis of data in both two- and three-dimensions identified reduced motion post-surgery and altered motion patterns compared to healthy controls. Notably, control females exhibited greater motion of the proximal phalange (middle thumb bone), potentially linking it to the onset of CMC OA. Additionally, unexpected substantial internal/external rotation was observed when the CMC joint was damaged or partially removed, suggesting muscle action as the primary driver of rotation. Thumb force evaluation indicated that standard clinical tools were inadequate for thumb force measurement and provided first-of-its-kind mapping of force vectors into the thumb kinematic space.

Overall, this research substantially advanced the ability to monitor thumb motion and thumb forces using new techniques that were highly visual and easy to interpret from a clinical perspective. The highly visual nature of the novel methods facilitates rapid translation of these techniques into the clinic, permitting the early detection of disease onset, patient-specific treatment routines, and ensures patient transparency about the outcomes of surgical intervention.

Persons with disabilities have the right to request and receive reasonable accommodation. Please call the Department of Mechanical Engineering at 355-5131 at least one day prior to the seminar; requests received after this date will be met when possible.