| abstract |
A intervertebral disc prosthesis, especially a nucleus pulposus prosthesis, includes prestressed hydrophilic material which undergoes a change in shape and/or expansion upon hydration. The prosthesis may be formed from a plurality of hydrophilic materials, such as an inner portion 1 of relatively low mechanical strength and an outer portion 2 of relatively high mechanical strength, said outer portion may have a peripheral region of hydrophilic material having low mechanical strength and high water uptake. The hydrophilic materials may be polymeric and may include fibrous reinforcement 3a, 3b. |