Anti-Leukotriene Receptor Blockers Improve Tendon-Bone Interface Healing in a Rat Model of Acute Rotator Cuff Tear

Background: Excessive expression of proinflammatory cytokines after rotator cuff (RC) surgery impairs the quality of tendon-bone interface (TBI) healing. There is evidence that the asthma drug montelukast (MS) inhibits the expression of proinflammatory cytokines. This study was conducted to verify the effect of MS administration on TBI healing after RC repair. Materials and Methods: Thirteen rats in the MS group were intraperitoneally administered 10 mg/kg of the drug daily for 2 weeks after RC surgery, and 13 rats in the control group were administered only 0.9% saline. The healing effect of the TBI was assessed through histologic and biomechanical analysis 4 weeks after tendon repair. Results: In the MS group, the expression of interleukin-1 beta (IL-1β; P<.01) and interleukin 6 (IL-6; P<.01) was significantly reduced compared with the control group. In the evaluation of supraspinatus fatty infiltration, the MS group showed significant inhibition of fatty infiltration compared with the control group (P<.001). Histologic analysis showed that the MS group had significant improvements in collagen density (P=.035) and alignment (P=.011). Biomechanical analysis after systemic administration of MS showed an increase in the cross-sectional area (P<.001) and elongation (P<.01) of the TBI. Conclusion: The use of MS improved tendon elasticity through suppressing fatty infiltration and improving TBI collagen density and arrangement. The mechanism is downregulation of IL-1β and IL-6. These results strongly support the use of MS as an anti-inflammatory agent that does not impair tendon healing.