Carpal Arch Space Augmentation (CASA) Clinical Trial

Carpal tunnel syndrome is a commonly diagnosed disorder of the hand that affects 3.7% of the population. Carpal tunnel release surgery can provide some symptomatic relief to patients but surgical transection of the transverse carpal ligament can disrupt essential anatomical, biomechanical, and physiological functions of the carpal tunnel. This clinical trial seeks to determine the effectiveness of the CASA device in alleviating CTS pain by augmenting the carpal arch space. During an early investigation of the transverse carpal ligament, investigators discovered the biomechanical mechanism of carpal arch space augmentation (CASA) for median nerve decompression. The CASA approach is supported extensively through research findings utilizing geometric modeling, finite element analysis, in vitro cadaveric experiments, and in vivo human studies.

In this proposed pilot clinical trial, investigators will compare the device's performance with a widely accepted standard of care (SOC) brace intervention (Thermoformable Exos# Wrist Brace, DJO, Vista, CA). Incorporating the CASA intervention as part of a brace is an innovative intervention study design offering a unique opportunity to identify the additive benefit of CASA and for patients to benefit from the combined effects of both CASA and a SOC.

This study is designed to be a randomized, single-blinded, two-arm trial. A sufficient number of patients will be recruited such that a total of 76 subjects will successfully complete the baseline run-in period and be randomized, with consideration of a 20% attrition rate among randomized patients, to yield 60 participants with complete data. The CASA group will be required to undergo wrist compression during the evening. The wrist compression is achieved by automated inflation of the balloon for a saturated pressure of 140 mmHg, which is calibrated to impart the targeted therapeutic compression force on the patient's wrist of 10 N. The intervention period will last for four weeks for the CASA group. For the SOC group, there is no compression force, as it is measuring a brace-alone condition, and will similarly last for a period of four weeks.

Patients will self-administer their assigned intervention of either CASA or sham device, and will have off-site access to study materials and questionnaire journals, thus reducing participant burden and eliminating travel expense. Data forms are designed to capture all data elements with the structure to facilitate completeness, quality, and statistical analysis. Furthermore, exploratory endpoints will be evaluated such as (a) number of participants that began to take analgesics during the study intervention phase, (b) the number of participants who opted for surgery during the intervention and post-intervention follow-up phases, (c) per-protocol comparisons of treatment arms, and (d) the impact of sex on response to treatment.

The trial will consist of 3 phases for participants; run-in, intervention, follow-up. During the run-in phase, subjects will be randomized and undergo compliance testing, along with a brief duration of device wearing, to ensure they conform with protocol instructions.

Once participants successfully complete the run-in, they will move into the intervention phase. During the intervention phase, subjects will wear their arm's respective device/brace nightly. Participants will report their adherence each day before falling asleep and once again upon waking. Participants will receive weekly phone calls in which they will report the outcome measures for the week to a member of the study team who will record the data.

After the intervention phase, participants will proceed to the follow-up phase which will last for four weeks. In this phase, participants will continue to receive weekly phone calls.

Regardless what the participant's compliance to protocol requirements for abstaining from analgesics or wearing the device 8 hours per day, the participant will be asked to complete their journals per protocol for the primary intent to treat outcome. The data gained from these patients will be used in an exploratory statistical analysis to determine if any significant differences exist between patients who were compliant to the study and those who were not. If adherence standards are not consistently met within either treatment group, a sensitivity analysis using a per-protocol cohort will be performed. A significance level of 0.05 will be assumed for tests of the primary outcome. Analyses of secondary outcomes will be interpreted cautiously due to multiple comparisons.

It is predicted that an intervention period of wearing the CASA device will significantly improve patient reported outcomes of the primary endpoint, BCTQ SSS, and some of the secondary endpoints. Furthermore, it is expected that the positive effects of the CASA device intervention will continue after the treatment period has concluded. In both long-term wear and combined CASA-brace effect, it is anticipated that the CASA device group will outperform the SOC group in alleviating patient symptoms.