Tendon Healing and Grafting Flashcards
Describe the strustural composition of a tendon
- Cellular
- tenoblasts- immature tenocytes
- tenocytes - spindle fibroblasts (90%)
- synovial cells
- chondrocytes (at insertion pts)
- Collagen type 1
- 3 troprocollagen fibrils ->fiber -> fiber bundle -> fascicles
- Ground substance
- HA, PG, LP GAG
Describe the blood supply of a tendon
STARRED FOR REVIEW?
Extrinsic (outside of synovial sheath)
- Paratenon
- Mesotenon - via vincula (Longus & brevis)
- Epitenon - sourrounded by paratenon
Intrinsic (wihtin synovial sheath of within tendon
- myotendinous and osteotedinous jxs
- Endotenon
(a different source says intrinsic supply is osseo- and myotendinous jxn, and extrinsic is paratenon [for extra-synovial] and vincula [for intra-synovial]????)
Describe tendon healing
INFLAMMATORY PHASE (1ST WEEK)
- Hematoma, recruitment of macrophage and PMN
- Epitendon cells proliferatie
- Fibroblasts invade and produce collage 3
PROLIFERATIVE PHASE (WK 1- WK3)
- fibroblasts deposit collage 3, ECM
- epitendon >endotenon key for collagen deposition
REMODELLING PHASE (>6WKS)
- drop in cellularity and collagen 3 production -> rise in collagen 1 production and reorientation
What factors promote extrinsic versus intrinsic healing?
Extrinsic healing (invasion of cells from surrounding and formation of adhesions)
- poor tendon apposition
- immobilization
- crush
- bacterial contamination
- damage of surrunding structures (devasculaized, fracture)
Intrinsic healing (I,P,R stages)
- mobilization
- good tendon apposition
- early repair
- tendon sheath preservation
- limited dissection
What are potential sites for tendon harvest and technique
- Palmaris longus
- 3mm, 15cm, 15% of population doesnt have one
- ulnar to FCR
- Plantaris
- 2mm, 25cm, 5% of population doesnt have one
- medial and anterior to achilles, 5cm vertical incision
- Long toe extensor
- of D2,3,4
WHAT IS THE CELLULAR STRUCTURE OF TENDON
- Tenoblasts and tenocytes - 90%
- Synovial cells, chrondrocytes, capillary endothelial cells - 10%
what structure detects changes in tendon tension / pressure ?
- golgi tendon organ
describe extrinsic vs intrinsic tendon healing
- extrinsic - tendon relies on immobilization and adhesions for repair (original thought was that tendons had no intrinsic capacity to heal)
- fibroblast ingrowth, neovascularization, fibrosis, adhesion
- intrinsic - tendon responsible for its own repair
- 3 stages of tendon healing
- inflammatory
- proliferative
- remodelling
- likely tendon healing is a combination of extrinsic and intrinsic methods; but knowledge that tendon can revascularize from paratenon (extra-synovial) or vincula/synovial diffusion (intra-synovial)