[Biodegradable devices for annulus fibrosus defect closure after lumbar discectomy]

To study the properties of materials and select the most suitable one for appropriate device covering annulus fibrosus defect after lumbar discectomy.

Prototype devices made of poly(L-)lactide, polycaprolactone (PLC) and copolymers of(L-)lactide and ε-caprolactone (LCL) without prior purification were used. Sponge materials were prepared using 1.4-dioxane without pretreatment. Physical and mechanical tests in compression were performed on Instron 5982 and Instron 5965 machines at a temperature of 37 °C in thermal chamber. Strain ranged from 0 to 80%, displacement rate - 50% of specimen height per a minute. Specimens were cylindrical in shape with a length of 10-15 mm and diameter of 8 mm. All experiments were performed in at least three repetitions. The ram lumbar spine was used as laboratory model.

Prototypes #2 made of PLC and LCL copolymers were the most perspective, but require partial or complete intraoperative removal of nucleus pulposus.

For all devices, we estimated their physical and mechanical characteristics, namely modulus and compressive strength, and compared these values with mechanics of native annulus fibrosus. A method for implant delivery to annulus fibrosus defect site was proposed for the developed devices, and bench tests of devices were carried out on the lumbar spine of the ram.

Polylactide and polycaprolactone prototype devices were the most perspective.