Comparative Mechanical Performance Analysis of Dynamic Compression Plates From Developing World Manufacturers

For a variety of reasons, notably the proliferation of motorized transportation, there has been dramatic growth in traumatic injuries in LMICs with an associated increase in the demand for implants used for open reduction and internal fixation of fractures. Although many governments will subsidize care for the poor, the cost of orthopaedic hardware can dwarf other aspects of care and is therefore frequently passed on to the patient. The resultant demand for lower-cost implants has been met by enterprising engineers in LMICs who are mass-producing implants for a fraction of previously standard prices. Implants are identical in design to those manufactured in high-income countries (HICs), but objective testing data refuting or substantiating mechanical property equivalencies are nonexistent. To further complicate matters, many manufacturers market their implants with a variety of international and local quality certifications that are unfamiliar to both surgeons and quality-control experts in HICs.

Clinically, it is known that hardware failure results in significant morbidity, but inferences about the impact of implant quality is confounded by differences between individual patients, fractures, and surgical techniques. As a result it is unknown whether premature failure can be attributed to subtle variations in design, differences in metallurgical composition, or other flaws in the manufacturing process associated with lower cost implants.

We envision this to be a pilot study to assess the possibility that there is a difference in mechanical behavior and composition of low-cost implants. Because the internationally accepted ASTM standard will be used, an abundance of data is available for comparison. Results will provide objective information for local surgeons and surgical mission groups when selecting hardware used to treat patients with fractures. To our knowledge, a similar study has never been conducted for any implants manufactured in LMICs. Future studies will test other types of orthopaedic implants to determine whether to accept or reject the assertion that there is an association between implant cost and quality. Ultimately, clinical studies will be needed to determine what level of mechanical performance is clinically relevant.

David Shearer, MD¹ Thomas Penoyar, MD² Jennifer Buckley, PhD¹ Harry Jergesen, MD¹ R. Richard Coughlin, MD, MSc¹

1 Department of Orthopaedic Surgery, University of California, San Francisco, USA

2 University of Washington School of Medicine

Abstract

Surgeons in low- and middle-income countries (LMICs) implant lower-cost hardware considered by many to be of lower quality than implants manufactured in Europe and North America. These orthopaedic hardware manufacturers offer a visually identical product at a fraction of the cost. The general consensus that “you get what you pay for” is unsubstantiated due to the lack of data that document the mechanical performance of such implants. The following aims are set forth to test the null hypothesis: “There is no difference in yield strength, fatigue resistance, or material properties of stainless steel fracture fixation plates from different low-cost manufacturers.”

1.) We will compare four point bending fatigue and yield of 10-hole stainless steel dynamic-compression plates from low-cost manufacturers of varying perceived quality. Testing will be performed according to American Society for Testing and Materials (ASTM) standards by a third party testing facility.

2.) We will conduct metallurgic analysis after mechanical testing to examine steel quality and to characterize failure patterns.