Tungwah Hospital of Sun Yat-sen University 1 article published in JoVE Developmental Biology A Mini-Invasive Internal Fixation Technique for Studying Immobilization-Induced Knee Flexion Contracture in Rats Shihai Jiang*1, Xiaoyou Yi*3, Yuansen Luo2, Dongjie Yu1, Yuangao Liu1, Fei Zhang1,4, Lei Zhu2, Kun Wang1 1Department of Joint and Trauma Surgery, The Third Affiliated Hospital of Sun Yat-sen University, 2Department of Plastic Surgery, The Third Affiliated Hospital of Sun Yat-sen University, 3Department of Bone Surgery, Tungwah Hospital of Sun Yat-sen University, 4Department of Othopaedic Surgery, The Eighth Affiliated Hospital of Sun Yat-sen University Here, we present a protocol to describe a minimally invasive technique for knee joint immobilization in a rat model. This reproducible protocol, basing on muscle-gap separation modus and the mini-incision skill, is suitable for studying the underlying molecular mechanism of acquired joint contracture.