Dynamic Mechanical Properties of Tendon Repair Tissue are Unaffected by Aging

Introduction Tendon injuries are common, especially in the aging population, and incomplete tendon healing is a well-established problem. Furthermore, aging tendons are at increased risk for injury due to changes in their mechanical properties and structural integrity. Age has also been correlated with poorer clinical outcomes for repaired tendons, which may be attributed to an inferior repair response. While a previous study investigating aging and healing in rabbit patellar tendons found no age-related mechanical alterations in uninjured or injured specimens, this study evaluated only quasi-static mechanical parameters. We have recently demonstrated that dynamic properties are more sensitive to changes due to damage from both aging and injury. Therefore, the objective of this study was to determine the effect of aging on dynamic properties in the healing patellar tendon in a murine model. We hypothesized that 1) tendons of aged mice will exhibit declining mechanical properties compared to mature mice, and 2) with more advanced age, the healing response will be inferior, leading to decreased mechanical properties in injured tendons.