Table 3:

Intrinsic vs. Extrinsic Healing. A comparison of the unique differences between intrinsic and extrinsic healing through the stages of tendon healing.

	Intrinsic Healing Tendon	Extrinsic Healing Tendon
Inflammatory Phase → first 24 hours after injury	Proliferation of tenocytes from epitenon and endotenon	Proliferation of fibroblasts and myofibroblasts from surrounding sheath and synovium
Repairing or Proliferative Phase → few days to 6 weeks after injury	Slow collagen synthesis from tenocytes	Rapid type III collagen synthesis from fibroblasts and healing process begins earlier ↓ Formation of adhesions
Remodeling Phase → 6 weeks after injury to final healing	Balanced MMP/TIMP ↓ Collagen fibers aligned in direction of tension	Unbalanced MMP/TIMP ↓ Disorganized and unaligned collagen fibrils even after remodeling
Final Outcome	Healed tendon with improved biomechanics and preserved tendon gliding mechanics	Tendon with adhesions, poor tendon gliding mechanics, and is biomechanically compromised.