Graduated properties mimic spinal disc

Degenerative Disc Disease is a debilitating condition that causes severe back pain, restricts mobility and affects quality of life. Conventional surgery sees the complete removal of a diseased disc, with the two adjacent vertebrae grafted together, restricting any further motion.

However, Cambridge based medical engineering firm Ranier Technology has developed a synthetic spinal disc. The aim is to replace a degenerative disc and restore near full movement to the patient. A major breakthrough in development of the Compliant Artificial spinal disc (CAdisc) was its material: a polyurethane-polycarbonate. The material has a graduated modulus, meaning it has a hard outer surface able to resist wear and abrasion, whilst yielding internally to permit movement and bending. Once implanted, the disc will mimic the dynamic, mechanical and motion characteristics of a natural disc. Polyurethanes are an important family of random segmented copolymers, with a range of mechanical properties. But their use has historically had limited use in medical applications due to batch-to-batch variations in physical properties and microstructures. Additionally, biomedical polyurethanes can undergo biodegradation, with roughening of the surfaces, cracking and loss of mechanical properties, which can lead to failure of long-term implants. The material has already been cited as suitable for other medical applications that include a haemocompatible blood pump, bio-active wound dressings. And, because many polyurethanes show excellent tissue-contacting characteristics, this raises the possibility of using the material for replacement heart valves, joints, catheters, stents and dressings. Meanwhile, Incorez supplies to a host of industries, including renewable energy, automotive and industrial, and will no doubt be seeking to exploit the technology where possible in the future. Ranier has formally expanded its ISO13485 Quality Management System (QMS) certification to include manufacturing activities. The QMS and key manufacturing activities were linked through the use of PTC Windchill, which it says, has been essential to demonstrating its controls during the audits. PTC also helped with its product development, the CAdisc-C, a disc replacement for the cervical spine. Ranier has recently been given the go ahead to start clinical trials on the CAdisc-L, the replacement disc for the lumbar region of the back, by the UK Medicines and Healthcare products Regulatory Agency. With a trial planned to take place in five European spinal surgical centres later this year, the technology could be rolled out more generally as soon as next year.