Thumb carpometacarpal (CMC) motion, motion between the thumb and the wrist, is primarily responsible for our ability to grasp objects, open jars, and makes up 50% of arm function^1,2. To improve hand function and the quality of life in persons with CMC osteoarthritis (OA), it is critical that we improve our ability to monitor changes in thumb function. The first step is to augment our methods to quantify the functional losses and used these methods to identify effects of treatment.

The overarching goal of this work was to quantify the differences in motion and force abilities of persons with and without thumb CMC OA, and to measure the ability of hand stretching and strengthening exercises to increase thumb function in persons with CMC OA. Initial motion and force datasets were collected from young healthy persons (n = 23), older healthy persons (n = 11), and older persons with diagnosed CMC OA (n = 24). Following collection of initial datasets, study participants were given daily hand stretching exercises. After two weeks, motion and force datasets were collected a second time. Participants then were given daily strengthening hand exercises to be completed in addition to the daily stretching exercises. Following four weeks of combined stretching and strengthening exercises, participant motion and force datasets were collected a final time.

For this work, there were three aims:​

Aim 1 was 1) to develop a method to measure isolated thumb forces in multiple directions, 2) to demonstrate this method on three populations, young healthy, older healthy, and older participants with OA of the CMC joint, and 3) to identify the effects of short-term hand exercises on thumb force production and grip strength in these three groups. Results showed that both thumb and grip forces improved in young healthy females, older healthy females and males, and older osteoarthritic females and males. In contrast, young healthy males increased their grip forces following exercise, but not their thumb strength. This suggests that thumb and strength forces are not interchangeable, and that thumb forces should be collected in a clinical setting to better track the effects of intervention (exercise, surgery, etc.) on thumb function.

Aim 2 was 1) to determine differences in thumb motions across three groups of participants (i.e., young healthy, older healthy and those with CMC OA) and 2) to determine if multi-planar motions provided additional movement information in comparison to standard planar measures. Both standard thumb ranges of motion typically collected in clinic and new multi-planar motion datasets were obtained from all participants. Results indicated that motion capture was capable of detecting changes in CMC mobility due to the effects of aging and OA pathophysiology that were not detected using standard approaches, and use of multi-planar measurements have the potential to identify changes that are indicators of early stages of OA.

Aim 3 was to identify changes in CMC motions as a result of a six-week exercise regimen on CMC OA participants as determined through two approaches 1) standard goniometry measures and 2) complex movements measured through the use of a motion capture system. We found that six weeks of exercise were sufficient to improve standard CMC ranges of motion using goniometry, and produce trends of improvement using motion capture.