Table 1.

Natural polymeric materials used in prevention of adhesion.

Material	Animal	Position	Follow-up (weeks)	Results	Reference
Cross-linked hyaluronic acid hydrogel	Rat	T11–T12,T12–L1, L3	8	Lower grade of epidural fibrosis, thinner dura mater and larger epidural and subarachnoid spaces; formed a solid interpositional membrane barrier	[22]
Hybrid chitosan membrane	Rabbit	L1–L3	4	Well-organised regenerating tissue integrated in the surrounding vertebral bone tissue with a regular and all-site interface on the chitosan sites	[26]
Amniotic membrane	Rat	Thoracolumbar junction	1–8	The amount of scar tissue and tenacity were reduced grossly; less inflammatory cell infiltration and fibroblast proliferation	[29], [30]
	Dog	L1, L3, L5, L7	1–12	Lower scar amount and adhesion tenacity; a white, slightly vascularised crossed-linked amniotic membrane layer without tenacious scar adhesion; reduced fibroblasts infiltration and epidural fibrosis (similar to autologous free fat)	[31]
Silk-polyethylene glycol (PEG) hydrogels	Rabbit		2–8	No or mild adhesion is observed in silk-PEG hydrogel samples	[32]