Primary loading causes bone cement-stem interface debonding injury / 中国组织工程研究

ABSTRACT

BACKGROUND: The main reason for the postoperative loosening of cemented prosthesis is interfacial debonding and bone cement internal damage. Most studies have suggested that both of them occur in the process of fatigue damage, however, little is reported on primary loading that results in the initial damage to the bone cement-stem interface and inside of bone cement. OBJECTIVE: To study the mechanical properties of bone cement-stem interface, and the effect of crack formation in bone cement on interfacial loosening. METHODS: The cement-titanium al oy handle implant components were prepared. The maximum adhesive force of bone cement-stem interface was measured using push-in experiment. The cement damage and crack in the process of bone cement-handle interfacial debonding were monitored online using acoustic emission tester. The non-destructive testing on the metal surface and the inner layer of bone cement cylinder was conducted using three-dimensional surface profiler, ultrasonic microscopy and X-ray detector. RESULTS AND CONCLUSION: The online monitoring results of debonding experiment and acoustic emission tester demonstrated that the initial damage of bone cement initiated in the primary loading of patients after operation, rather than at fatigue damage stage. Bone cement coffin caused cracks initiation mainly due to the combination effect of radial and axial stress. The bone cement-stem interfacial shear lag effect could not prevent the gradual extension of interface and inner coffin crack from top to bottom. The bone cement defects formed in solidification process was likely to affect the mechanical properties of the material, and eventual y induced the crystal face and macromolecular chain fractures, forming silver striated cracks and leading component failure.