Introduction: Surgical site infection is a growing and expensive complication. Surgical site surveillance is performed with the aid of laboratory tests and clinical evaluation; the latter has some limits, including reproducibility and validation of results and, as suggested by many authors, the need of a dedicated well trained staff. At present no imaging instruments are available for routine objective monitoring of “normal” or complicated surgical site healing. Recently, technological improvement made available for clinical use high resolution portable digital telethermocameras at relatively low-costs. No data are available in the literature, concerning the “physiological” thermographic pattern of surgical wounds in orthopaedics. The aim of this study is then to evaluate the physiological telethermographic pattern of surgical site healing after hip and knee prosthetic surgery, to provide a reference value for further analysis.

Methods: The surgical site of 60 consecutive patients undergoing total hip replacement and 40 patients unde-going total knee replacements were examined at fixed intervals from the day before surgery to six weeks after intervention, using a portable telethermographic camera (AVIO TVS-200EX). Results were compared with contralateral side and with laboratory data.

Results: A physiological “telethermographic pattern” of wound healing was observed and showed to be remarkably reproducible among different patients. A thermographic peak was observed at day 3, with a mean temperature elevation (hottest spot) of 2.3 +− 1.3 ^C after hip replacement and of 2.8 +− 1.5 ^C after total knee replacement. Similar results were obtained when considering the mean surface temperature in a 10 cm rectangle area identified around the surgical wound. Temperature at the surgical site slowly returned to baseline (contralateral side as reference) in a six weeks period.

Discussion and Conclusion: Telethermography through a portable camera appears a reliable, not invasive, not irradiating and easy-to-use tool to monitor surgical site following hip or knee arthroplasty at the patient’s bed. Surgical site show a highly reproducible physiological thermographic pattern, with peak values at day 3 and a constant decrease until normal values at week 6 after surgery. This findings may be used as a reference for further studies, to establish the relevance of abnormal thermographic patterns in connection with surgical site complications.

BIONs (Bionic Neurons) are microminiature stimulators that can be injected into muscles. They receive power and commands from an external magnetic field. They have been shown to be safe and effective for stimulating muscles in animals. Clinical trials are underway to assess the efficacy and safety of BIONs for therapeutic exercise of weak or paralyzed muscles. In patients with knee osteoarthritis weakness of quadriceps muscle has been shown by different authors to be highly correlated with pain and functional impairment, while quadriceps strengthening is associated with significant improvements of clinical scores. Preliminary results of the use of BIONs to strengthen the quadriceps muscles in patients affected by knee osteoarthritis are reported.

Five patients have been recruited so far, three of them have completed the protocol. Patients are implanted with BIONs near the common femoral nerve and in the vastus medialis muscle, and stimulated for 12 weeks. Therapy starts three days after implantation with two-three stimulation sessions of 10–30 minutes each day. Stimulation parameters are intended to recruit the quadriceps muscles (up to 10 X threshold for muscle twitch) at relatively low frequencies (5–13 pps) in short trains (5–10 s) with pauses between trains (5 s). Outcome measures include WOMAC, Knee Society Score, muscle measurements with MRI, gait analysis, isokinetic tests. All patients found muscle stimulation to be agreeable. No adverse events or complications have been observed. Thresholds for eliciting muscle contractions remained stable over time. In the three patients knee function improved and pain decreased over the stimulation period, while muscle thickness, as measured by MRI, increased.

Results are preliminary but encouraging. We anticipate studying 15 patients to demonstrate clearly the safety and efficacy of this technology in this application. Plans are underway for additional clinical trials in orthopaedic patients as well as in stroke patients.