Description
Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013) Hydrogels offer unique opportunities for regenerative strategies of the
intervertebral disc. A nucleotomy necessary for the implantation of hydrogels,
however, disrupts the annulus integrity and destroys natural
interfaces in the disc. To clarify whether hydrogels can restore the
mechanical competence of the disc an experimental testwas used. Intradiscal
pressure(IDP) in an ovine disc was measured in vivo for 24 h and
adapted to an axial compressive test consisting of three cycles 15-min
diurnal and 30-min night load. To study the fluid mechanics, 30 motion
segments in different defect conditions were used: (i) INTACT; (ii) DEFANN:
isolated annulus defect; (iii) DEF-NUC: re-implanted nucleus; (iv)
DDAHA and (v) iGG-MA: two hydrogels. DEF-ANN showed no significant
difference in disc height loss or IDP compared to INTACT, while
DEF-NUC reduced the IDP by ~30%(p = 0.03) and tended to increase
the height loss(p = 0.2). Both DDAHA and iGG-MA better reflected the
height loss of INTACT, but caused an even stronger loss in IDP than
DEF-NUC(~34%). Neither the hydrogels nor the re-implanted nucleus,
assumed to be the ideal implant, could restore the mechanical functionality
of the disc. Hydrogels designed to mimic the mechanical behavior
of the native nucleus may fail in restoring IDP due to the destruction of
natural interfaces and an inappropriate annulus closure. To regain a biomechanical
equivalent of the natural nucleus, more attention needs to
be paid to the anchoring of the substitute inside the disc.
; Wolfram, U. 
