II.

As a simple type I collagen sponge seems to increase the amount of local collagen type I, the careful use of such sponges might be an option for tendon augmentation during Achilles tendon surgery.

Therapeutic study, Level III.

Although incision or resection of the paratenon has been advocated when repairing injured or degenerative tendons, our data suggest that the integrity of the paratenon should be preserved.

bFGF, BMP-12, VEGF and TGF-β1 are differentially expressed during tendon healing. Additional BMP-12 or TGF-β1 has no significant influence, whereas ACS generally increases expression of all factors except VEGF. Staged application of multiple growth factors may be the most promising biomolecular treatment.