Effects of Cryotherapy Applied at Different Temperatures on Inflammatory Pain During the Acute Phase of Arthritis in Rats

Ryo Sasaki; Junya Sakamoto; Yasutaka Kondo; Satoshi Oga; Idumi Takeshita; Yuichiro Honda; Hideki Kataoka; Tomoki Origuchi; Minoru Okita

doi:10.1093/ptj/pzaa211

Effects of Cryotherapy Applied at Different Temperatures on Inflammatory Pain During the Acute Phase of Arthritis in Rats

Phys Ther. 2021 Feb 4;101(2):pzaa211. doi: 10.1093/ptj/pzaa211.

Authors

Ryo Sasaki^{1

2}, Junya Sakamoto³, Yasutaka Kondo⁴, Satoshi Oga^{1

4}, Idumi Takeshita⁵, Yuichiro Honda³, Hideki Kataoka^{1

6}, Tomoki Origuchi¹, Minoru Okita¹

Affiliations

¹ Department of Locomotive Rehabilitation Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
² Department of Rehabilitation, Juzenkai Hospital, Nagasaki, Japan.
³ Department of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
⁴ Department of Rehabilitation, Japan Red Cross Nagasaki Genbaku Hospital, Nagasaki, Japan.
⁵ Department of Rehabilitation, Faculty of Medicine, University of Miyazaki Hospital, Miyazaki, Japan.
⁶ Department of Rehabilitation, Nagasaki Memorial Hospital, Nagasaki, Japan.

PMID: 33351944
DOI: 10.1093/ptj/pzaa211

Abstract

Objective: The biological mechanisms of cryotherapy for managing acute pain remain unclear. Additionally, it is unknown whether the effectiveness of cryotherapy depends on the applied temperature. This study aimed to clarify the biological effects of cryotherapy and to examine the therapeutic effects of cryotherapy applied at different temperatures in rats.

Methods: This was an experimental study using a rat knee joint arthritis model. Thirty-five Wistar rats were randomly divided into arthritis (AR), arthritis with 5°C cryotherapy (CR-5), arthritis with 10°C cryotherapy (CR-10), and sham-arthritis control (CON) groups. Arthritis was induced by injecting a mixture of kaolin/carrageenan into the right knee joint. Cryotherapy was applied for 7 days starting the day after injection by immersing the right knee joint in 5°C or 10°C water. Joint transverse diameter, pressure pain threshold, and pain-related behaviors were assessed for 7 days. The number of CD68-positive cells in the knee joint and the expression of calcitonin gene-related peptide in the spinal dorsal horn 8 days after injection were analyzed by immunohistochemical staining.

Results: Improvements in transverse diameter, pressure pain threshold, and pain-related behaviors were observed in the CR-5 and CR-10 groups on the 3rd day compared with the AR group. The number of CD68-positive cells and the expression of calcitonin gene-related peptide in the CR-5 and CR-10 groups were significantly decreased compared with the AR group. There were no significant differences in all results between the CR-5 and CR-10 groups.

Conclusions: Cryotherapy can ameliorate inflammatory pain through reduction of synovium and central sensitization. Additionally, the effects of cryotherapy lower than 10°C are observed independent of applied temperature.

Impact: Cryotherapy may be beneficial as a physical therapy modality for pain and swelling management in the acute phase of inflammation. Translational human study is needed to determine the effective cryotherapy temperature for the inflammatory pain.

Keywords: Acute Pain; Animal; Arthritis; Inflammation; Models; Pain Management; Physical Therapy Modalities.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Arthritis / physiopathology
Arthritis / therapy*
Central Nervous System Sensitization / physiology
Cryotherapy / methods*
Disease Models, Animal
Edema / physiopathology
Edema / therapy*
Inflammation / physiopathology
Inflammation / therapy*
Knee Joint
Male
Pain Management / methods*
Pain Threshold / physiology
Rats
Rats, Wistar
Temperature