By: 1 November 2007

The spine is a challenging area for surgeons as there is very little space to manoeuvre during surgery and, as always, there is a constant pressure to minimise the time a patient spends under anaesthesia.

It is not surprising, therefore, that there is continual innovation and evolution in the design of implants and instruments.

The commercial challenge facing OEMs is how to get these designs from idea to finished product, both cost effectively and quickly.

Prototyping is essential to achieving this as it translates the OEM's clinical design into a product that can be manufactured affordably; and ensures that every step of the manufacturing process can be controlled and documented, which is crucial for securing regulatory approval.

Obviously, before making any commitment to production, the OEMs need to be certain the design will actually work. Developing an initial prototype will highlight any issues in the design itself and these can then be addressed. But having a working prototype does not mean the product can be manufactured cost effectively.

This is where the skill and expertise of the manufacturer comes in. Sandvik aims to be a strong strategic partner to OEMs, working in close collaboration to address the complex challenges of manufacturing instruments and implants.

Long experience in prototyping

Kenny Cleveland, General Manager at Sandvik Medical Solutions' (formerly Doncasters Medical Technologies) Alabama Operations, has been manufacturing orthopedic devices since 1992.

Kenny started the operation in Alabama in 1985 working in the aerospace and medical sectors, responsible for developing, amongst other things, some of the parts on the Space Station. For the past three years the business has concentrated solely on the medical sector, deepening its expertise. The aim for Kenny and his team is to bring value to their customers. OEMs' engineers utilise Computer aided design (CAD) systems which contain finite element analysis and 3-D modeling to create increasingly complex designs. However, this very complexity may result in a product that is expensive to produce. Kenny's team looks at these designs from the OEMs and works closely with their engineer to build “manufacturability” into the final product. The goal is to focus on the final production requirements to reduce manufacturing cost and improve time to market, without any compromise to the efficacy of the product.

Clockwise from top left: Machine operator running an EDM wire machine ; Kenny Cleveland and the Sandvik plant

“One area we can make a difference is in knowing how to balance tolerances,” explained Kenny. “Every aspect of the design has upper and lower limits on tolerances and we use our judgement to assess the impact of moving towards the upper or lower end. Slight shifts within the tolerance levels can have a major impact on the fit, function and operating mechanisms of the final instrument and whether or not the manufacture of a product is affordable.”

“We also look at the specified materials. For example an OEM asked us to manufacture a retractor which does the job of spreading the tissue and muscle apart giving the surgeon access to the spine. We discussed the possibility of changing the material from a 300 series stainless to a 17-4ph stainless. The consequence was that the heat treatable material provided better functionality of the component when assembled. A longer life span for the instrument in the field was also projected.

“Another example relates to a torque measuring device. The device had to be able to repeat measurements precisely every time. To deliver this we examined the design, considered the materials and recommended a manufacturing process.

“We work closely with OEMs and approach each project from a manufacturing perspective to make suggestions that typically include balancing tolerances and adding or removing features such as radii or chamfers. The earlier in the development process this interaction takes place then the greater the positive impact our suggestions may have.”

The other key area in which the prototyping process is vital is in ensuring the right quality levels. Manufacturing to the higher regulatory classifications requires complete traceability throughout the manufacturing process. The Sandvik team's previous experience of the aerospace sector underpinned a culture throughout the manufacturing facility that made it straightforward to implement the required, internationally recognised ISO 13485:2003 quality system.

Kenny explained: “The aerospace sector also places extremely high demands on suppliers. Even the tiniest component on the Space Station must be traceable right through its entire production process.

“We have brought forward the disciplines we developed in this sector to our work with spinal implants and instruments. All our prototypes and production processes are developed under the direction of the international quality standard.”

Recognizing the OEM's need for qualified manufacturing assistance when developing new products, Sandvik