Duration and Magnitude of Myofascial Release in 3-Dimensional Bioengineered Tendons: Effects on Wound Healing

Context: Myofascial release (MFR) is one of the most commonly used manual manipulative treatments for patients with soft tissue injury. However, a paucity of basic science evidence has been published to support any particular mechanism that may contribute to reported clinical efficacies of MFR. Objective: To investigate the effects of duration and magnitude of MFR strain on wound healing in bioengineered tendons (BETs) in vitro. Methods: The BETs were cultured on a deformable matrix and then wounded with a steel cutting tip. Using vacuum pressure, they were then strained with a modeled MFR paradigm. The duration of MFR dose consisted of a slow-loading strain that stretched the BETs 6% beyond their resting length, held them for 0, 1, 2, 3, 4, or 5 minutes, and then slowly released them back to baseline. To assess the effects of MFR magnitude, the BETs were stretched to 0%, 3%, 6%, 9%, or 12% beyond resting length, held for 90 seconds, and then released back to baseline. Repeated measures of BET width and the wound’s area, shape, and major and minor axes were quantified using microscopy over a 48-hour period. Results: An 11% and 12% reduction in BET width were observed in groups with a 9% (0.961 mm; P<.01) and 12% (0.952 mm; P<.05) strain, respectively. Reduction of the minor axis of the wound was unrelated to changes in BET width. In the 3% strain group, a statistically significant decrease (–40%; P<.05) in wound size was observed at 24 hours compared with 48 hours in the nonstrain, 6% strain, and 9% strain groups. Longer duration of MFR resulted in rapid decreases in wound size, which were observed as early as 3 hours after strain. Conclusion: Wound healing is highly dependent on the duration and magnitude of MFR strain, with a lower magnitude and longer duration leading to the most improvement. The rapid change in wound area observed 3 hours after strain suggests that this phenomenon is likely a result of the modification of the existing matrix protein architecture. These data suggest that MFR’s effect on the extracellular matrix can potentially promote wound healing.