Telethermographic findings after uncomplicated and septic total knee replacement

Thermal imaging with infrared thermography is a noninvasive approach to monitoring surgical site healing and detecting septic complications. The aim of this study was to set reference values for telethermographic patterns of wound healing after total knee replacement (TKR) not complicated by infection and to compare them against thermograms from patients with knee prosthesis infection. Forty consecutive patients operated for TKR underwent telethermography of the operated and the contralateral knee before and up to 12 months after uncomplicated surgery. The imaging data sets were then compared against those obtained starting 8months after TKR in 15 other patients with diagnosed periprosthetic infection. Presurgical assessment thermograms showed no difference between the affected and the healthy knees. At assessment 3days postoperative, the temperature of the operated knee had increased markedly, with a peak differential temperature (operated minus non-operated knee joint temperature) of 3.4±0.7°C; measurement at 90 days after surgery showed a return to baseline knee joint temperature in the patients with uncomplicated surgery. In the patients with septic complications, the mean differential temperature was 1.6±0.6°C (range, 1.1-2.5°C). Thermal imaging showed a measurable, reproducible telethermographic pattern of surgical site healing in patients with uncomplicated TKR and an elevated mean differential temperature >1.0°C in those with persistent prosthesis infection.