Neuroplasticity of sensory and sympathetic nerve fibers in a mouse model of a painful arthritic joint.

Objective: Many forms of arthritis are accompanied by significant chronic joint pain. This study was undertaken to investigate whether there is significant sprouting of sensory and sympathetic nerve fibers in the painful arthritic knee joint and whether nerve growth factor (NGF) drives this pathologic reorganization.

Methods: A painful arthritic knee joint was produced by injection of Freund's complete adjuvant (CFA) into the knee joint of young adult mice.

Breast cancer-induced bone remodeling, skeletal pain, and sprouting of sensory nerve fibers.

Unlabelled: Breast cancer metastasis to bone is frequently accompanied by pain. What remains unclear is why this pain tends to become more severe and difficult to control with disease progression. Here we test the hypothesis that with disease progression, sensory nerve fibers that innervate the breast cancer bearing bone undergo a pathological sprouting and reorganization, which in other nonmalignant pathologies has been shown to generate and maintain chronic pain.