Biomechanical evaluation of internal fixation augmented with calcium phosphate cement in treatment of proximal humeral fractures

Abstract

Objective To compare injectable calcium phosphate cement (CPC) and polymethyl-methacrylate (PMMA) in their biomechanical performances in augmenting the fixation for osteoporotic proximal humeral fractures. Methods Forty-two humeral specimens were obtained from aged female corpses soaked in the formaldehyde. They were made models of three-part proximal humeral fracture. The specimens were randomized evenly into CPC group, PMMA group and control group. Biomechanical tests involving compression, stretching and axial pulling-out of cancellous screw were conducted to determine the maxiulum compression load, tensile load and initial loosening load of screw. Results The values of maximum compression load, tensile load and initial loosening load of screw in CPC and PMMA groups were significantly higher than those in control group (P 0.05) . Conclusion Since the biomechanical performances of injectable CPC are similar to those of PMMA, injectable CPC may be used as a fine substitute of PMMA to enhance the in-ternal fixation for osteoporotic proximal humeral fractures. Key words: Calcium phosphate cement (CPC); Osteoporosis; Humeral fracture; Biome-chanics