Early failure of bioabsorbable anterior cervical fusion plates: case report and failure analysis.

STUDY DESIGN: Case report with forensic failure analysis. OBJECTIVE: To determine the failure modes of 3 explanted 70:30 PLDLA Mystique (Medtronic Sofamor Danek, Memphis, TN) graft containment plates retrieved from revision surgery for early device failure. SUMMARY OF BACKGROUND DATA: To reduce the problems of stress-shielding and radiopacity associated with metallic systems, bioabsorbable polymers have been used in anterior cervical discectomy and fusion procedures. Degradation of mechanical properties in vivo is a major concern when using bioabsorbable systems. Three of 6 patients who underwent anterior cervical discectomy with instrumented fusion, using Mystique graft containment systems experienced early failure requiring revision to alternate hardware. METHODS: Devices were retrieved after failure and analyzed by light microscopy and environmental scanning electron microscopy. Simulations were performed with an unused plating system to induce damage for comparison with the retrieved devices. A detailed case review was performed to identify possible sources of extraordinary loading or damage. RESULTS: One plating system failed at 6 weeks postimplantation due to fatigue fracture of the screws. Crack initiation sites were identified at the interface of the thread root and mold line of the screw. Another plating system failed at 16 weeks postimplantation due to the coalescence of radial microcracking between holes in the plate, leading to catastrophic failure of the plate. The final plating system failed during the implantation surgery, when the screw fractured in torsion. CONCLUSIONS: Stress concentrations at the screw head-shaft interface and thread-shaft interface reduce the fatigue performance of bioabsorbable screws. Hydrolysis of the polymer may also play a role in the reduction of resistance to crack initiation and propagation.

Does academic dishonesty relate to unethical behavior in professional practice? An exploratory study.

Previous research indicates that students in engineering self-report cheating in college at higher rates than those in most other disciplines. Prior work also suggests that participation in one deviant behavior is a reasonable predictor of future deviant behavior. This combination of factors leads to a situation where engineering students who frequently participate in academic dishonesty are more likely to make unethical decisions in professional practice. To investigate this scenario, we propose the hypotheses that (1) there are similarities in the decision-making processes used by engineering students when considering whether or not to participate in academic and professional dishonesty, and (2) prior academic dishonesty by engineering students is an indicator of future decisions to act dishonestly. Our sample consisted of undergraduate engineering students from two technically-oriented private universities. As a group, the sample reported working full-time an average of six months per year as professionals in addition to attending classes during the remaining six months. This combination of both academic and professional experience provides a sample of students who are experienced in both settings. Responses to open-ended questions on an exploratory survey indicate that students identify common themes in describing both temptations to cheat or to violate workplace policies and factors which caused them to hesitate in acting unethically, thus supporting our first hypothesis and laying the foundation for future surveys having forced-choice responses. As indicated by the responses to forced-choice questions for the engineering students surveyed, there is a relationship between self-reported rates of cheating in high school and decisions to cheat in college and to violate workplace policies; supporting our second hypothesis. Thus, this exploratory study demonstrates connections between decision-making about both academic and professional dishonesty. If better understood, these connections could lead to practical approaches for encouraging ethical behavior in the academic setting, which might then influence future ethical decision-making in workplace settings.