Calcium Sulfate Versus PMMA in One Stage Repair of Critical-sized Femoral Defects: A Vitro Study

Abstract Polymethylmethacrylate (PMMA) cement has been used in Masquelet technique to repair bone defects, but it needs additional surgery like bone grafting. This study was to compare the efficacy between PMMA and calcium sulfate (CS) used as a spacer in one-stage reconstruction of critical-sized segmental bone defects. Sprague Dawley rats (n=30) were used to create models of critical-sized femoral defect (5mm) which were then randomized into CS, PMMA and control groups equally. the bone defects were filled with CS, PMMA or nothing. Gross observation, digital radiography, histological observation and micro-computed tomography were conducted at week 20 after surgery for comparison between the three groups. The expression of Osterix, Nestin and Osteocalcin at the bone defects was also detected by immunofluorescent staining. The results of X-Ray and μCT showed that new bone formation in CS group was superior to that in PMMA group. H&E, Safranin O & fast green and Masson staining showed obvious endochondral ossification and fibrocartilage tissues at the ends of bone defects in CS group. Much more new bone tissue formed near the ends of bone defects in CS group. In addition, osteogenic and angiogenic activities were significantly increased in CS and PMMA groups. Compared with PMMA and control groups, the expression of Osteoblast-associated protein at the bone defects in CS group was higher. In general, due to the degradability of CS and superior osteogenesis ability, CS may replace PMMA as a new filling material in clinical application.