Objective: The objective of this study is to evaluate the effect of therapeutic cold on the recovery process after an incomplete muscle strain injury.

Method: We made incomplete muscle strain injuries with the predefined extent. Unilateral tibialis anterior (TA) tendons were detached at their distal insertions and stretched beyond the complete rupture points. The incomplete strain injury point was identified on the deformation- tension curve. We strained each TA of 18 rabbits to 20% deformation point and held for 2 seconds. After injury, we applied ice packs for 5 minutes on unilateral TA. Histologic findings were examined at 1, 2 days, 2, 4, 5 weeks.

Results: Incomplete strain injuries were occurred at 19.36⁑4.02% deformation. In the acute phase, cold applied TA showed fewer (15.4⁑4.2) inflammatory cells infiltration than control TA (21.8⁑5.3) at LPF (×40). But, there was no significant difference between cold applied TA and control in the recovery phase.

Conclusion: It is possible to develop certain amount of incomplete muscle strain injuries. The results of this study suggest that the cold therapy may reduce the inflammatory reaction in the acute phase of muscle strain injury. The findings provide no significant support for the positive or negative effect of cold therapy on incomplete strain injury.

The purposes of this study are to investigate the effect of the cold air application in the skin and intraarticular temperature changes and to observe the rebound temperature changes after cooling.

We recorded the changes of the skin surface and intraarticular temperatures of knees during and after the cold air application. The intraarticular temperature was measured by a temperature probe inserted into the knee joint cavity and the skin temperature by the infrared system. Eighteen healthy subjects were examined. The knee was cooled by a 5-minutes application of CRAis (Kyung-won Century, Korea) machine and the intraarticular and skin temperatures of knees were measured at every 0.5-minute during and after the cold therpy, then at every minute for 5 minutes, and every 5-minute for the next 110 minutes. We also evaluated the variables that might affect the skin and intraarticular temperature changes.

Results showed that the mean skin temperature dropped from 31.8℃ to 10.5℃ immediately after the cold air application for 5-minutes. The mean intraarticular temperature dropped from 33.9℃ to 30.0℃ after the cold air application for 5-minutes. Two hours after the initiation of treatment with cold air, the mean intraarticular temperatures did not recover to the baseline values(p＜0.01). No significant correlations were found between the body mass index with the intraarticular and surface temperatures of knees. A highly significant correlation was noted between the baseline skin surface and intraarticular temperatures(p＜0.01).

In conclusion, the reduction of the joint temperature by the cold air application using CRAis machine can be a useful treatment method for the synovitis of knees.