Patent attributes
Multi-membrane prosthetic nucleus and implants using same are disclosed having an outermost membrane that is semi-compliant and limits the innermost membrane and any intermediate membranes that are highly compliant from bulging out of any opening in the annulus fibrosus. The outermost membrane may help protect the innermost membrane from trauma including any trauma before the innermost membrane is expanded through the injection of prosthetic nucleus material and trauma during the expansion of the innermost membrane in response to the injection of prosthetic nucleus material. Also disclosed is a coated membrane which combines the mechanical properties of the foundation layer with the low permeability to the passage of the flowable prosthetic material of the coating. This coated membrane is semi-compliant and prevents the prosthetic nucleus from bulging out of any openings in the annulus fibrosus. Use is made of injected prosthetic nucleus material that changes to a non-flowable state.
