Low-Level Laser Therapy Prevents Treadmill Exercise-Induced Progression of Arthrogenic Joint Contracture Via Attenuation of Inflammation and Fibrosis in Remobilized Rat Knees.

We investigated whether the combination of exercise and anti-inflammatory/anti-fibrotic treatment using low-level laser therapy (LLLT) promotes recovery from joint contracture without arthrogenic contracture progression. Rat knees were immobilized for 3 weeks in a flexed position. 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. After 7 days of remobilization, m-ROM restriction decreased equally in all groups. Conversely, a-ROM restriction further increased after remobilization in the RM and WALK groups. Furthermore, 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 1 or 7 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. m-ROM restriction representing total contracture initially established by immobilization was partially improved by remobilization. Additional LLLT and exercise intervention did not further reduce total contracture, but LLLT suppressed the progression of arthrogenic contracture caused by ambulation and treadmill exercise. Therefore, exercise with LLLT in the early phase of remobilization would be one possible adjunct therapy to prevent further progression of arthrogenic contracture.