Alterations in deep tissue temperature around the knee after total knee arthroplasty: its association with knee motion recovery in the early phase.

PURPOSE: Cryotherapy has been employed to reduce postoperative inflammation for enhancement of the recovery of total knee arthroplasty (TKA). However, the clinical advantages in functional recovery after TKA remain controversial. This study was conducted to clarify the postoperative alterations in deep temperature around the knee and to evaluate the association between the temperature changes and functional recovery in the early phase after TKA.

METHODS: Postoperative changes in deep temperature around the knee were evaluated with the probe that can measure subcutaneous tissue temperature at the depth of 1 cm in 28 patients with medial knee osteoarthritis undergoing unilateral TKA through medial parapatellar approach. The same rehabilitation protocol was provided without cryotherapy. Outcome assessment included knee range of motion (ROM) and 10-meter fast speed walking test.

RESULTS: The operated knee showed a greater increase in deep temperature at postoperative days 1 and 2, followed by a gradual decrease by day 14 when the temperature was still higher than the baseline. When deep temperature change around the operated knee was calculated by subtracting the preoperative temperature from the highest postoperative one, significant association was found between deep temperature change and knee ROM recovery at day 14. The operated knees with more than 2°C increase in postoperative deep temperature resulted in poor ROM recovery. There was no association of deep temperature change with 10-meter fast speed walking test improvement at day 14 or ROM recovery at 1-year follow-up.

CONCLUSIONS: This study has provided the first data on deep temperature alterations around the knee after TKA. More than 2°C increase in postoperative deep temperature could result in poor ROM recovery after TKA. The results may support establishment of adequate procedures of cryotherapy for early gain in knee motion after TKA.