• 1. Department of Orthopaedics, Wuxi No.9 People’s Hospital Affiliated to Suzhou University, Suzhou Jiangsu, 214062, P. R. China;
  • 2. Orthopedic Research Institute, Wuxi No.9 People’s Hospital Affiliated to Suzhou University, Suzhou Jiangsu, 214062, P. R. China;
RUI Yongjun, Email: ruiyongjun_md@163.com
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Objective To investigate the causes of spontaneous osteogenesis of Masquelet induced membrane. Methods Forty-two male Sprague-Dawley rats aged 7-9 weeks were selected to establish a critical-sized bone defect of the right middle femur model. Then the rats were randomly divided into 4 groups, with 12 rats in groups A-C and 6 rats in group D. The bone defects in groups A-C were filled with vancomycin-loaded polymethyl methacrylate bone cement spacers. Then the Kirschner wires were used for intramedullary fixation in groups A and B, and the bone cement was used to connect the bone cement spacers and the bone ends in group B. The steel plate was used to fixation in group C. The bone defect in group D was only fixed with steel plate as a blank control group. The general condition was observed after operation. At 5 weeks after operation, 6 rats in groups A-C were selected for STRO-1 immunohistochemistry to observe the content of mesenchyme stem cells (MSCs) in the induced membrane (STRO-1+ cells). At 12 weeks after operation, the remaining rats in groups A-D were taken for X-ray observation, gross observation, and histological observation (HE, safranin O-green staining) to observe the effect of inducing spontaneous osteogenesis of the membrane. Results  All rats in the 4 groups survived until the completion of the experiment. At 5 weeks after operation, the immunohistochemical staining showed that group B was negative, while the contents of MSCs in the induced membrane in groups A and C were 14.20%±1.92% and 5.00%±0.71%, respectively, with a significant difference (P<0.05). At 12 weeks after operation, group A showed significant new bone growth towards the center of the bone defect at the osteotomy site, with an average length of 3.1 mm on one side. Histological observation revealed the presence of bone and cartilage lesions, fibers, and a small amount of neovascularization in the induced membrane. Group C only had a small amount of new bone at the bone end, while groups B and D did not have any new bone, but bone resorption or atrophy at the bone end and a small amount of neovascularization were noted in the induced membrane. Group D showed collagen fiber proliferation and a small amount of neovascularization. Conclusion Although the induced membrane of Masquelet technology has osteogenesis, the key factor for the spontaneous osteogenesis of the induced membrane is the bone marrow overflow from the bone marrow cavity providing MSCs. The presence of bone and cartilage in the new bone indicates the spontaneous osteogenesis of the induced membrane belongs to endochondral ossification.