CARTILAGE GRAFTS

1. Cartilage grafts
• Cartilage is a kind of connective tissue
which is mainly composed of
chondrocytes and their extracellular
• matrices (ECM) of
• type II collagen fibers,
• proteoglycans, and
• elastic fibers.

2. • According to its composition,
• cartilage can be classified into three
types:
• hyaline cartilage;
• fibrocartilage; and
• elastic cartilage.

3. • Hyaline cartilage is the most common type of
cartilage and can be found in
• costal,
• articular,
• tracheal, and
• nasal cartilage.

4. • Fibrocartilage is composed of bundles of
thick collagen fibers,
• along with intervening unicellular islands
of cartilage arranged in small chains.

5. • Because of this unique structure,
fibrocartilage can provide
• high tensile strength and
• supporting function and
• is thus present in areas that are most
subject to frequent stress,

6. such as
• meniscus,
• intervertebral discs,
• symphyseal joints, and
• the joint portion of bone and
tendons/ligaments.

7. • Elastic cartilage is characterized by its
extremely high elasticity because of the
presence of abundant amounts of elastic
fibers.
• It is histologically similar to hyaline
cartilage but contains many elastic fibers
• Which form an elastic fiber network
along with collagen fibers.

8. • This unique feature provides great
flexibility so that elastic cartilage can
withstand repeated bending.
• It is mainly found in
• the outer ear structure,
• the larynx and
• epiglottis.

9. • Cartilage is a unique tissue with low
metabolic rate due to the sparsity of its
cell population and its avascular
structure.
• The glycolytic activity and oxygen
• consumption of cartilage approaches
anaerobic condition and the tissue is
nourished by tissue fluid diffusion.
Metabolism of cartilage

10. • This unique non dependence on blood
supply ensures that
• cartilage grafts will survive by imbibing
surrounding fluids and
• are therefore far more reliable in terms
of what is called as a ‘take.

11. • cartilage is considered as
“immunologically privileged,”
• and allogeneic cartilage may serve as a
potential graft,
• autologous cartilage grafting remains
• the most applicable cartilage graft.

12. According to surgical procedures,
• cartilage can be transferred either as a
free graft.
• or as a microvascular composite graft.

13. Auricular cartilage graft
• As an elastic cartilage, auricular cartilage
is an ideal graft
• for transplantation and
• perhaps is the most versatile of all
cartilage grafts
• because it can be easily fashioned and
contoured into
• different shapes for
• various uses.

15. • Auricular cartilage can be harvested
easily under local anesthesia and
• a significant portion of the concha can
be removed
• without causing donor site deformity.

17. • Auricular cartilage graft is often
• used as a framework for ear
reconstruction or
• auricular deformity correction.

18. • In addition, conchal cartilage can be
used as a single-layered graft for
• nasal,
• tarsal, and
• nipple reconstruction.
.

19. • The other important application of
auricular cartilage
• is to transfer as
• a composite chondrocutaneous graft
• for nasal reconstruction.

20. Nasal cartilage graft
Although limited in its available amount,
nasal cartilage has been employed as a
composite chondromucosal graft for eyelid
reconstruction.

21. • Septal cartilage is an important source of
nasal cartilage graft.
• The septal cartilage can be accessed via a
hemitransfixion incision with dissection
around the caudal margin of the
quadrangular cartilage.
• After both sides of mucoperichondrium
are raised, the septal cartilage can be
harvested.

22. • The other region available for harvesting nasal
chondromucosal graft is the upper lateral
nasal cartilage,
• as reported by Tessier in 1979.

23. • In addition to eyelid repair,
• septal cartilage graft has been used for
• dorsal augmentation,
• tracheal repair, and
• extended septal graft for controlling the
projection and shape of nose tip.

24. • Alar batten grafts are thin, oval shaped
cartilage grafts that are placed along the nasal
sidewall in the area of the supra-alar crease or
area of lateral wall weakness.

25. • A spreader graft is a cartilage graft that is
insert between the septum and upper
lateral cartilage,
• thereby widening the area of narrowing
and opening up the internal nasal valve.
The cartilage is usually carved from septal
cartilage that is removed during a
concurrent septoplasty.

27. Rib cartilage graft
Costal cartilage may serve as the best
donor site for cartilage graft in terms of
available tissue amount and
mechanical strength..

28. • The autologous rib cartilage can be
• virtually contoured into any desired
shape and
• it can retain form and bulk after
implantation
• if basic surgical principles are followed.

29. • The costal cartilage graft is often used
as a cartilage framework.
• for total ear reconstruction.

30. Cartilage engineering

31. • The tissue-engineering process involves
• three major components:
• (1) seed cells: the component for matrix
production, deposition, and tissue
formation;
• (2) scaffold: the substance that provides a
3D place for cells to reside, proliferate,
and produce matrix;
• (3) tissue formation environment:.

32. • After being seeded on the scaffold,
• cells start to grow and produce and
deposit ECMs on the scaffold.
• In a proper environment, with gradual
• degradation of the scaffold,
• cell proliferation,
• matrix production, and
• proper tissue remodeling, an engineered
• tissue gradually forms and becomes
mature.

34. • .

35. Causes of nerve injury
• Focal contusion(Gun shot wounds)
• Traction injury
• Injection injury
• Compression
• Crush injuries
• Avulsion
• Laceration
• Electrical burns
• Others( infections, metobolic)
• idiopathic

36. CLASSIFICATION OF NERVE INJURY
• Classified by
• Seddon, sunderland and lately by Mackinnon.
• Into six degress

37. Degrees of nerve injury
• Ist degree ( Neurapraxia)
• Segmental demylination
• Axons intact
• Recovery in 12 to16 weeks
• 2nd degree injury( axonotmesis)
• Axonal injury/ distal wallerian degeneration
• Regeneration at the rate of1 inch per month
• Complete slow recovery

38. Degrees of nerve injury
• 3rd degree injury
• Axonal injury & fibrosis of endoneurium
• Incomplete recovery
• 4th degree injury
• Axonal injury
• Damage to endo and perineurium with dense
scarring
• Needs surgical intervention

39. Degrees of nerve injury
• 5th degree injury( neurotmesis)
• Complete nerve division
• 6th degree injury
• Variable combination of previous five degrees

41. • Primary neurorrhaphy is the gold standard by
which all other nerve repair techniques are
judged.
• Excessive tension will inhibit nerve
regeneration; however a small amount of
tension to achieve primary coaptation is
acceptable

42. • Nerve autograft is the gold standard for
reconstructing a nerve gap.
• In the event of a nerve gap, options for
repair include:
• • mobilization and primary coaptation
• • nerve repair with nerve graft or conduit
• • nerve transfers.

43. Indications of nerve grafting
• Tension at site of repair.
• Need of postural positioning
• Alignment of sensory & motor components
• Maximize number of axons
• Reversal of graft
• Exclusion of expendable nerve

44. Factors most affecting nerve recovery include:
• age of the patient
• location of injury (proximal versus distal
peripheral nerve)
• type of injury: crush versus avulsion versus
transection
• timing or repair
• technique or repair (tension, alignment,
scarring).

45. Advantages Disadvantages
Nerve autograft Gold standard for
reconstruction
Schwann cells in extra
cellular matrix
Second operative site
Results in donor sensory loss
Potential for neuroma
formation/pain
Sensory nerve autografts do
not support motor
regeneration
as well as motor or mixed
sensorimotor nerves
Limited available length
Allograft Can potentially allow
functional recovery
equivalent to
autograft
No donor site morbidity
Patients
Requires patient systemic
immunosuppression (~18
months)
Patients vulnerable to
opportunistic infections

46. NERVE GRAFT TAKE

47. • Under ideal circumstances, the nerve
graft will behave as the distal nerve
stump would.
• Therefore, the graft must also undergo
wallerian degeneration to provide a
conduit for axon regeneration.

48. • Schwann cell survival in the graft is critical to
this process.
• For the Schwann cells to survive, the graft
must be appropriately revascularized.
• This process occurs both from the proximal
and distal nerve stumps and from the
surrounding tissue bed. In animal models,
graft revascularization reaches supranormal
levels in 4 to 5 days.

49. • Initial revascularization occurs through the
proximal and distal stumps and then the
surrounding tissue.
• Ingrowth from local tissue creates extensive
adhesions, which limit graft excursion.
• The first few days after grafting, cellular
viability is dependent solely on diffusion
from the tissue bed

50. • As graft size increases, central cellular
necrosis occurs,
• because the volume of nerve tissue
increases beyond the limits of perfusion or
revascularization.
• This limitation contributes to poor outcome
with trunk grafting.
• Trunk grafts are now used uncommonly,
unless harvested as vascularized nerve
grafts.

51. Nerve Grafting Techniques
In group fascicular grafting, every attempt
is made to accurately deliver regenerating
axons through the graft material to a
matching fascicular group in the distal
stump.
The distal nerve tissue may be marked and
sent for histochemical staining, depending
on clinical needs and laboratory
capabilities.

52. • After graft harvest and careful hemostasis,
grafts are sutured to individual fascicular
groups with the minimally needed number
of sutures.
• Emphasis again is placed on appropriate
fascicular matching without tension

53. • Individual fascicular grafting is
uncommon.
• A distal digital nerve defect is a
specific, useful indication for individual
fascicular grafting.
• Other indications may arise when
clinically critical single fascicles (eg, the
thenar motor branch) can be
identified.

54. Graft Material
• Autogenous nerve graft is the most
commonly used material for bridging
nerve gaps.
• Ideally, the donor nerve provides a
suitable environment for regeneration
and results in acceptable donor
morbidity.

55. • The sural nerve
• Through a longitudinal incision or
sequential small transverse incisions,
up to 40 cm of nerve can be harvested
from each leg.

56. • In the forearm, cutaneous nerve branches
are available as graft material.
• The medial antebrachial cutaneous nerve
(MACN) may be harvested and provides up
to 10 cm of graft.

57. .
• The lateral antebrachial cutaneous nerve
provides significantly more graft material
than the MACN does -- up to 20 cm.
• However, the resultant sensory loss along
the lateral aspect of the forearm can extend
onto the thenar area,
• making it undesirable for median nerve
defects in general and thumb digital nerve
injuries in particular.

58. • The posterior interosseous nerve may be
harvested at the wrist level and yields
approximately 3.5 cm of graft material.
The graft may be particularly useful in
digital nerve defects, and there is no
donor morbidity from sensory loss.

59. • The use of vascularized nerve grafts
provides several potential advantages.
• The initial period of ischemia (2 to 3 days)
after nonvascularized grafting is avoided,
• the necessity for revascularization via the
recipient bed (which may be severely
scarred and poorly vascularized) is
eliminated, and
• larger sizes of nerve tissue (in cross
section) may be used as graft without the
problems of central necrosis.

60. • There is experimental evidence that
vascularized nerve grafting can produce
superior outcomes,
• though conclusive evidence is still
lacking.

61. • The most compelling present indication is
grafting in a severely scarred tissue bed.
• Situations where transfer of large nerve
trunks is desirable and feasible
• (eg, brachial plexus reconstruction using
the ulnar nerve) may benefit from this
technique, as well.

62. Nerve Vascular Supply
Superficial radial Radial artery
Ulnar Superior ulnar collateral artery
Sural Superficial sural artery
Anterior tibial Anterior tibial artery
Superficial peroneal Superficial peroneal artery
Saphenous Saphenous artery
Vascularized Nerve Grafts: Donor
Nerves and Associated Vessels

63. THANKS