Pledget Sensor to Monitor Loading in Tendon and Ligament Sutures During Postoperative Physical Therapy

Tendon and ligament injuries are common complications in orthopedic and sports medicine. Tears to tendons and ligaments, many of which are treated surgically via suturing, require postoperative physical therapy to restore tissue structure and function. However, to effectively treat these injuries, the duration and intensity of rehabilitation need to be regulated to prevent tissue reinjury while promoting regeneration. Currently, physical therapy procedures following tendon and ligament repair rely on qualitative factors such as tissue swelling or patient pain tolerance, which can prevent optimal healing outcomes due to the patient and medical caregiver variability. Therefore, the goal of this project is to develop and characterize a sensing platform for detecting tension magnitude in sutures for rehabilitation applications. Specifically, a wireless suture pledget sensor was engineered to provide quantitative biofeedback during physical therapy by monitoring tension in sutures after soft tissue repair. To measure suture loading, an electrical resonance biosensor was integrated into the design of commercially available suture pledgets. This innovative approach had many advantages over previous suture monitoring systems including remote operation and passive function. In this work, a prototype suture pledget sensor was fabricated for proof-of-concept functionality studies. Loading experiments showed that the sensor could reliably detect suture loading forces ranging from 2 to 12 N, while signal transmission distance through tissue mimics was tested up to 16 mm. Overall, this device could be used to develop evidence-based physical therapy guidelines to accelerate rehabilitation and improve healing outcomes for patients with tendon and ligament injuries.