Low-level laser therapy prevents progression of arthrogenic joint contracture of remobilized rat knees during treadmill exercise

抄録

【Background/Purpose】

 Previous studies have reported that treadmill exercise during remobilization period improves overall range of motion (ROM) (includes both myogenic and arthrogenic factors), but further decreases ROM after myotomy (includes arthrogenic factor only) through inflammatory and fibrotic reactions in the joint capsule. These suggest that treadmill exercise during remobilization period can improve total contracture via improvement of myogenic contracture, while it further develops arthrogenic contracture. We investigated whether the combination of treadmill exercise and anti-inflammatory/anti-fibrotic treatment using low-level laser therapy (LLLT) can promote recovery from joint contracture without arthrogenic contracture progression.

 

【Methods】

 Rat knees were immobilized for three weeks. After fixator removal, rats were divided into no intervention (RM), daily treadmill walking (WALK), and daily treadmill walking and LLLT (W + L) groups. Total and arthrogenic contractures were assessed by restrictions of passive range of motion (ROM) before (m-ROM) and after myotomy (a-ROM), respectively.

 

【Results】

 m-ROM restriction was equally decreased by seven days of remobilization in all three groups. Conversely, a-ROM restriction further increased after remobilization in the RM and WALK groups, and this restriction was significantly larger in the WALK group compared with the RM group. In the W + L group, however, progression of a-ROM restriction during remobilization was prevented. After one or seven days of remobilization, inflammatory and fibrotic reactions in the joint capsule were induced in the RM group and were more pronounced in the WALK group, but these reactions were milder in the W + L group than in the WALK group.

 

【Discussion/Conclusion】

 Additional treadmill exercise and LLLT intervention did not promote recovery of total contracture, but LLLT suppressed the progression of arthrogenic contracture caused by ambulation and treadmill exercise. Therefore, the combination of LLLT and exercise would be one possible adjunct therapy to prevent further progression of arthrogenic contracture.

 

【Ethical consideration】

This experimental design was approved by the committee on animal experimentation of Hiroshima International University.