Mechanical behaviour of low-cost dynamic compression plates correlates with manufacturing quality standards

Abstract

Purpose

This study compares the mechanical properties of low-cost stainless steel dynamic compression plates (DCPs) from developing-world manufacturers, adhering to varying manufacturing quality standards, with those of high-cost DCPs manufactured for use in the developed world.

Methods

Standard-design ten-hole DCPs from six developing-world manufacturers and high-cost DCPs from two manufacturers in the developed world were studied. Nine plates from each manufacturer underwent mechanical testing: six in four-point monotonic bending to assess strength and stiffness and three in four-point bending fatigue. Statistical comparisons of the group means of monotonic bending test data were made, and a qualitative comparison was performed to assess failures in fatigue.

Results

Low-cost DCPs from manufacturers with at least one manufacturing quality standard had significantly higher bending strength and fewer failures in fatigue than did those from low-cost manufacturers with no recognised quality standards. High-cost DCPs demonstrated greater bending strength than did those in both low-cost groups. There were no differences in stiffness and fatigue failure between high-cost DCPs and those low-cost DCPs with quality standards. However, high-cost DCPs were significantly less stiff and had fewer fatigue failures than low-cost DCPs manufactured without such standards.

Conclusion

Significant differences were found in the mechanical properties of ten-hole DCP plates from selected manufacturers in the developing and developed worlds. These differences correlated with reported quality certification in the manufacturing process. Mechanical analysis of low-cost implants may provide information useful in determining which manufacturers produce implants with the best potential for benefit relative to cost.

Appendix

• i) International Organization for Standards (ISO) 9001 is a Quality Management System (QMS) that describes the requirements that manufacturing organizations must fulfill to meet the needs of consumers. This standard requires third party certification to confirm independently that the ISO 9001 requirements are met.

• ii) ISO 13485: This certification contains requirements for a comprehensive quality management system specific for the design and manufacture of medical devices. It requires that the quality system be implemented and maintained. Unlike ISO 9001, it does not require a third party to confirm continued compliance.

• iii) GMP: Good Manufacturing Practice requirements represent a quality management system covering the manufacture of medical devices. GMP covers aspects of production and testing that can have an impact on the quality of a product, involving processes in design, manufacture, packaging, labeling, storage, installation, and servicing of all finished devices intended for human use. This certification is issued locally, and designated cGMP if current.

• iv) Medical Device Directive (MDD) 93/42/EEC: this guideline ensures that devices are designed and manufactured in a way that does not compromise the clinical condition or safety of a patient and that they fulfill the manufacturer’s intended purpose. It requires manufacturers to demonstrate safety, quality, and efficacy before their product can be sold to consumers.

• v) European Conformity (CE): This certification is issued by an independent certification body after verification that a medical device manufacturer is in compliance with MDD 93/42/EEC.

  • a. CNC: Issued by a German certification company in compliance with Medical Device Directive MDD 93/42/EEC.

  • b. CE 1293: Issued by a Chinese certification company in compliance with MDD 93/42/EEC.

  • c. CE 0086: Issued by a UK certification company in compliance with MDD 93/42/EEC.

  • d. CE 1023: Issued by a Czech Republic certification company in compliance with MDD 93/42/EEC.

  • e. CE 0434: Issued by a Norwegian certification company in compliance with MDD 93/42/EEC.