Biomechanical mechanisms of early gait training on knee cartilage degeneration after anterior cruciate ligament reconstruction: a study protocol. - Dang, Ruiqin; Lu, Yiqun; Zhou, Ziren; Zhou, Zheng; Cui, Na; Yu, Yuanyuan; Zhang, Si; Ao, Yingfang; Huang, Hongjie; Wang, Jianquan; Ren, Shuang (Frontiers in Sports & Active Living, 2026)