Medical graft

1. CARTILAGE HEALING AND GRAFT
DR. SURBHI ABROL (MCH RESIDENT)
DEPARTMENT OF PLASTIC AND RECONSTRUCTIVE SURGERY.
CHENGALPATTU GOVERNMENT MEDICAL COLLEGE AND HOSPITAL.

2. INTRODUCTION
 KIND OF CONNECTIVE TISSUE
 Derived from mesoderm
 Biphasic material
 COMPOSED OF CHONDROCYTES & EXTRACELLULAR MATRICES
 DIVIDED INTO 3 TYPES:
1.Hyaline cartilage
2.Fibrocartilage
3.Elastic cartilage

3. CARTILAGE UNIQUE POINTS
 Unique tissue with low metabolic rate
 Glycolytic activity and oxygen consumption of cartilage approaches anaerobic condition and tissue nourished by
tissue fluid diffusion.
 Thus it is relatively more easy to survive.
 Perichondrium possesses the ability to regenerate cartilage.

4.  Hyaline cartilage is the most common type of
cartilage.
 Found in costal, articular, tracheal, and nasal
cartilage.
 Covered with perichondrium except articular
cartilage.
 Rich in glycosaminoglycans and collagen-2
 Characterized by its stiffness, that permits
sustained compressional loading.
HYALINE CARTILAGE

5. FIBROCARTILAGE
 Bundles of thick collagen fibres along with intervening unicellular islands of cartilage.
 High tensile strength and supporting function so present in meniscus, intervertebral discs,sympyseal joints,joint
portion of bone and tendons/ligaments.
 Contains collagen-1, and little glycosaminoglycans.

6. ELASTIC CARTILAGE
 Abundant elastic fibres
 Found in outer ear structure,larynx,epiglottis.
 Surrounded with Perichondrium.

7. CARTILAGE TYPES AND RESPONSE TO INJURY

8. PERICHONDRIUM
 Dense irregular connective tissue
 2 separate layers- Outer fibrous layer and Inner chondrogenic layer.
 Collagen fibres and fibroblast constitute the fibrous layer
 Chondrogenic layer partially undifferentiated contain mesenchymal stem cells and chondrogenic progenitor cells.
 Inner zone is usually absent in adult tissues.

10. CARTILAGE INJURY
 Injury or lesions to ear or nasal cartilage can stimulate the Perichondrium to proliferate.
 Accompanying vessels can facilitate scar formation.
 Cartilage healing in articulating joints is critical to long term function.
 Partial lesions- isolated from repair by having no direct source for cellular invasion or blood supply.
 Thus current strategy is to cause microfracture or drilling to the subchondral bone to permit blood and cell
invasion.

11. HEALING
 SILVERMAN performed experiments to analyse interaction between the engineered cartilage and native cartilage
in vivo.
 Neocartilage was found to fill all irregularaties along the cartilage disk surface without any gaps.
 Demonstrated that tissues engineered cartilage produced by use of a fibrin –based polymer permitted adherence to
adjacent cartilage and withstand forces significantly.

12.  Seeding density of cells capable of chondrogenesis in or onto a polymer carrier is a critical ingredient for
successful engineering.
 Avoiding chondrocytes growth in low density monolayer culture.
 Use of other mesenchymal cells with chondrogenic potential may permit generation of cartilage.

13. AUTOLOGOUS CARTILAGE GRAFTS

14. AURICULAR CARTILAGE GRAFTS
 Ideal graft for transplantation.
 Versatile
 Harvested easily under local and significant concha can be removed.
 Conchal cartilage can be used as a
A. single layered graft for nasal ,tarsal, and nipple reconstruction.
B. Composite chondrocutaneous graft for nasal reconstruction.

15. TECHNIQUES TO DEAL WITH DONOR SITE IN FREE
AURICULAR COMPOSITE GRAFTS

22. NASAL CARTILAGE GRAFT
 Composite chondromucosal graft for eyelid reconstruction.
 Septal cartilage important source.
 Dorsal augmentation, tracheal repair, extended septal graft for
Controlling the projection shape of nose tip.

23. pedicled nasal chondromucosal flap for
upper eyelid reconstruction. (A)
Preoperative markings for harvest of the
upper lateral cartilage in the nasal
chondromucosal flap, which is based on
the lateral terminal branch of the dorsal
nasal artery. (B) After skin incision and
undermining, the flap is raised after a
portion of the upper lateral cartilage
(ULC) is harvested. NB, nasal bone;
LLC, lower lateral cartilage; SC, septal
cartilage.

24. RIB CARTILAGE GRAFT
 Costal cartilage may serve as the best donor site for cartilage graft in terms of available tissue amount and
mechanical strength.
 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.
 Often used as a cartilage framework for total ear reconstruction.

25. TECHNIQUES
 Tanzer, Thomson et al. and Brent have respectively described the technique to harvest costal cartilage to construct
auricular framework.
 In the procedure, the synchondrosis of the sixth and seventh cartilages as well as the eighth costal cartilage is
harvested, usually along with the perichondrium.
 Nagata’s method for total auricular reconstruction requires the harvest of four costal cartilages in the first-stage
operation and one or two costal cartilages for the second-stage operation

27. COMPLICATIONS
 Harvest of costal cartilage can be associated with donor site morbidity.
 Pain and clicking of the chest wall, which usually peaked in the first week post surgery and diminished over 3
months.
 Most challenging problems are: Pneumothorax (particularly true for nagata’s)

28. MODIFICATION
Kawanabe and Nagata –
1.The costal cartilages were harvested en bloc with
the perichondrium left completely intact at the
donor site.
2.After the fabrication of the auricular cartilage
frame, the remaining costal cartilage was cut into
small blocks that acted as spacers to fill the dead
space formed in the perichondrial pocket.
3.The retained perichondrium not only helps to
avoid the injury of pleura, but may also promote
cartilage regeneration because of the presence of
chondrogenic stem cells.

30. AUTOLOGOUS PERICHONDRIAL GRAFT
 FIRST DESCRIBED BY LESTER
 Thinness and malleability,
 Perichondrium is particularly suitable for covering every part of the cartilaginous graft,
 Easy to fold into various layers if greater thickness is required in filling certain areas
 Mainly used in reconstruction of degenerated knee joint cartilages.
 Nasal reconstruction.

31. Reconstruction of the nasal tip with lateral
crural and shield grafts (Sheen-type)
harvested from the cartilage of the
auricular concha. (B) Graft of the
perichondrium stretched over and secured
to cartilaginous grafts to make the contours
smooth and disguise tip grafts. (C) Lateral
view of the same graft. (D) Schematic
illustration of the perichondrium graft
positioning and fixation.

32. TISSUE ENGINEERING OF CARTILAGE
 Combination of cells with a biocompatible polymer resulting in the formation of functional tissue units.
 Providing quality cartilage graft tissue - new cartilage to meet the requirements for the repair.
 Material properties of synthetic or natural compounds can be manipulated to allow delivery of an aggregate of
dissociated cells into a host that will result in formation of new tissue.
 Consideration of properties of the tissue native to the site and properties of polymer being used to generate or
regenerate the cartilage repair tissue.
 Used in Auricular reconstruction, Rhinoplasty and facial contouring and joints – TMJ and digital joints.

36. Chondrocytes seeded on to the polymer ear mold in
vitro. (A) seeded with chondrocytes (1.5 × 10°).
(B) adherence of chondrocytes to polyglycolic acid
device before implantation.

37. Gross mechanical testing of the
ear-shaped framework at 12
weeks after insertion
demonstrates a continued high
degree of flexibility. (C) After
mechanical testing, the
framework easily recovers its
initial shape. (D) Hematoxylin
and eosin staining of flexible
tissue-engineered, demonstrating
the tight adherence at the
interface between neocartilage
and the lyophilized swine
perichondrium laminate.

38. SCAFFOLDS
 NATURAL/ BIOLOGICAL SCAFFOLDS
 SYNTHETIC SCAFFOLDS

39. NATURAL SCAFFOLDS
A. COLLAGEN- Type-1 collagen from bovine tendon.
 Porosoity, biodegradability, biocompatibility.
 Either single collagen or composite of 2 or more types.
 Disadvantages- foreign body reaction.
B. HYALURONAN- undifferentiated mesenchyme in developing embryo.
 Allows synthesis of matrix components and differentiation of progenitor cells.
C. Hydrogels- fibrin glue and alginate.- delivery vehicle for isolated chondrocytes.

40. SYNTHETIC SCAFFOLDS
1.Specimens of cartilage engineered
into specific shapes determined by
the design of the polyglycolic acid
polymer scaffold.
2.Cartilage engineered in
predetermined shapes employing
cell transplantation on synthetic
biodegradable polymers.

41. INERT NON-RESORBABLE MATERIALS
 Expanded polytetraflouropolyethylene - biocompatible material that has been used successfully in a multitude of
biomedical and clinical applications.
 Microporous structure that allows biointegration for soft tissue fixation as well as overall mechanical integrity.
 ePTFE membrane is firm enough to sustain the tension placed on the surface of the engineered
 the chondrocytes permeated the micropores of ePTFE membrane and produced neocartilaginous matrix, forming a
tight bond between ePTFE.

42.  This integration of cartilage and ePTFE membrane formed a flexible cartilage framework with a
pseudoperichondrium.
 When the polymer is placed on both surfaces of the composite, the ePTFE membrane can maintain the flexibility
of tissue-engineered cartilage.
 A pseudoperichondrial layer similar in structure and position to the native perichondrium could provide the
necessary flexibility for making suitable tissue-engineered cartilage for craniofacial repair.

43. FUTURE
 Stem cell based cartilage engineering
 In vitro engineering of cartilage with enhanced mechanical strength.

44. REFERENCES
 NELIGAN PLASYOC SURGERY- 4TH EDITION – VOLUME 1
 MATHES GENERAL PRINCIPLES 2ND EDITION – VOLUME-2
 PLASTIC SURGERY KEY.

45. THANK YOU