Cranioplasty

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Cranioplasty

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Cranioplasty

  1. 1. CRANIOPLASTY Dr. Joe M Das Senior Resident
  2. 2. • • • • • • • • • • History Definition Bone-graft integration Indications and contraindications Preservation of autografts Critical size & anatomy of defect Graft materials Pediatric plasty Complications Future
  3. 3. HISTORY PETRONIUS (1565) GOLD PLATES FALLOPIUS (1600) BONE MEEKEN (1670) CANINE BONE MACEWEN (1888 ) REIMPLANTATION BURREL BONE BUTTON SEYDEL (1889) TIBIA MULLER (1890) OUTER TABLE SKULL
  4. 4. HISTORY WESTERMAN (1916) BROWN (1917) STERNUM RIB DAMBRIN (1919) MACLENAN (1920) FAGARASANU (1937) CADAVER SCAPULA SPLIT RIB VON HINTERSTOISSER BOOTH CORNIOLEY (1925) CELLULOID ALUMINIUM PLATINUM CARNEY KLEINSCHMIDT (1940) TANTALUM METHYLMETHACRYLATE
  5. 5. • The first reported cranioplasty was probably that of a Russian nobleman who, after receiving a sword blow to the head, had the resultant defect (and his health) restored with a piece of dog‘s cranium (Van Meekeren, 1668). • Subsequently, after he had been excommunicated from the Russian church (which could not accept the presence of animal bone on a human skull), removal of the graft was impossible due to bony union.
  6. 6. Definition The restoration of a defect in the cranial bone or correction of a deformity of the bone that may happen after trauma as in depressed fracture
  7. 7. Bone graft integration • The dynamic nature of living bone was first realised in 19th century. • In 1893 the histological sequence of bone replacement, ‘creeping substitution’ • Survival of a bone implantation graft depends on the reaction of the surrounding tissue and on functional contact between cancellous bone and adjacent resident bone.
  8. 8. • 1st week → Capillaries from surrounding bone diploe, dura and scalp infiltrate the transplant bed. • 2nd week → fibrous granulation tissue proliferates and osteoplastic activity occurs. • Osteoinduction – – Primitive mesenchymal cells → Osteoprogenitor cells → Osteoblasts that are capable of forming newbone to replace the necrotic bone which is gradually absorbed
  9. 9. • Osteoconduction – Osteoprogenitor cells from the surrounding tissue migrate into the 3-D structure of bony and protein matrix. • Auto- and allo-grafts have relied on osteoconduction as the main principle of cranioplasty. • In osteoinduction, cells do not have to migrate from the surrounding tissues but, probably with the help of bone morphogenetic proteins, can be produced in situ.
  10. 10. • Osteoactivity – Ability of the biomaterial to be replaced with bone formation either through osteoinduction / osteoconduction • Osteoproductivity – The process whereby a bioactive surface is colonised by osteogenic stem cells from the defective environment as a result of surgical intervention
  11. 11. AETIOLOGY OF THE CRANIAL DEFECT • • • • • Trauma Decompressive craniectomy Infection Neoplasms Congenital: Encephalocele, meningoencephalocele, large parietal foramina, aplasia cutis congenita, cranium bifida, sphenoid wing defect
  12. 12. INDICATIONS • Aesthetic / protective / discomfort • Those prone for trauma - seizure disorder, sports, military • ? Local tenderness • ? Post traumatic seizure • Hemispheric collapse • Children—asymmetric growth and cerebral hernia
  13. 13. INDICATIONS • GRANT AND NORCROSS (1939) 1. 2. 3. 4. 5. Severe headache and syndrome of trephined Epilepsy assumed to be due to defect Danger of trauma Unsightly defect Pulsate unduly and painful
  14. 14. When to do it? • 3-6 months after compound wounds • 1 year after wound infection / if frontal sinus is opened • 3 months with autograft • Wait for 1 year after craniectomy in a child
  15. 15. SYNDROME OF THE TREPHINED • Yamura and Makino (1977) coined the term “syndrome of the sunken skin flap” to describe the neurological symptoms due to a craniectomy defect • Progressive contralateral hemiparesis, local pain and postural headache with cognitive and functional decline due to a skull defect • Not affected by size or location of defect • Early cranioplasty may improve the symptoms
  16. 16. SYNDROME OF THE TREPHINED • Pathophysiology – Stretching of the dura and underlying cortex due to the atmospheric pressure – Cicatrical changes occurring between the cortex, dura and the skin exerting pressure on the skull contents – Impairment of the venous return due to the atmospheric pressure acting on the region of skull defect with a resultant increase in the local external pressure
  17. 17. SYNDROME OF THE TREPHINED • How does cranioplasty work? – Increase in cerebrospinal fluid (CSF) and superior sagittal sinus pressure, cerebral expansion, increase in CSF motion after cranioplasty due to an increase in cerebral arterial pulsations and improvement in cerebral blood flow, cerebral metabolism and cerebral vascular reserve capacity have been demonstrated after cranioplasty.
  18. 18. CONTRAINDICATIONS • • • • • Hydrocephalus Cerebral oedema Infection Compound wound Contiguous functional sinus
  19. 19. IDEAL • • • • • • • • • • Malleable Easy to sterilize Strong Light-weight Easily securable Non ferro-magnetic Inexpensive Bio-compatible & chemically inert Radiolucent Readily available
  20. 20. Preservation of autografts • In the interim - “hockey helmet” • Boiling (Westermann – 1916) • Alcohol / formalin / autoclaving  Bone resorption & infection • Bone flap in abominal wall (Kreider – 1920)  Another operation, unsightly scar, no osteogenic potential • The bone flap remains sterile in a −70°C freezer for many months. • Autoclaving of the bone (e.g., if contaminated by a compound scalp wound before cranioplasty)  reduce the viability of the graft. • ETO sterilisation
  21. 21. Critical size of defect • Bone defects > 2 cm on the cerebral convexity and bone defects of glabrous frontal region • No need for repair in – Defects below the temporal & occipital muscles – Very elderly – Children < 6 yrs in whom dura is not damaged – Parietal area defect < 5 cm2
  22. 22. Anatomy of the defect
  23. 23. Preparation of the cranial defect • The surgical bed must be clean and free of debris • Both surgical bed and overlying surgical flap must be well-vascularised • Incorporate the previous scar into repair • Scars in hair-bearing areas, avoiding parallel ones • Cranialise the sinus • Pericranium brought up as second layer with pedicle intact • Bone edges freshened • Meticulous hemostasis & gentle handling of soft tissues • Any foreign material that is used should be perforated
  24. 24. AUTO BONE GRAFT • Wrap in blood soaked sponge for 4-6 hrs • More than 6 hrs → 10 % serum / 90 % salt solution at 3 C. • Don’t expose to air for more than 30 min. • Normal saline is toxic • Avoid antibiotic soak • Split bone graft – Outer & inner tables split
  25. 25. • RIB – 3-4 times more resorption – Contour deformity – Difficult to stabilize • ILIUM – Post op pain – Second operation site – Difficult to contour • TIBIA – Small segments – Difficult to contour – # Tibia • VASCULAR FLAP – IRRADIATED TISSUE
  26. 26. Cranioplasty after left decompressive hemicraniectomy for intractable intracranial hypertension. A. Preoperative CT scan demonstrating Lt skull defect B. autologous bone flap secured to native skull with plating system C. Postoperative computed tomographic scan demonstrating cranioplasty
  27. 27. POLYMETHYL METHACRYLATE • • • • • • • Inert Minimum reaction Tight adherence Not thermoconductive MRI compatible Prepare intra-operatively Powder polymerised ester of acrylic acid + benzoyl peroxide liquid monomer (2:1) • A paste-like substance into a translucent material with strength comparable to that of native bone
  28. 28. • • • • Exothermic – 1000°C 20 minutes Mix in plastic bag Evaporated monomer → Hypotension, hypoxia, CV collapse, death
  29. 29. Cranioplasty after resection of right frontal meningioma with growth through the skull. • A skull defect • B methyl methacrylate sheet over skull defect • C methyl methacrylate plated into skull defect. • D Postoperative CT scan
  30. 30. Hydroxyl apatite • • • • • • Tissue compatibility is high Radiolucent Readily available Adhere to bone Bioactive – Capable of osteoconduction MRI signal void
  31. 31. Nova Bone (Porex Surgical) • Synthetic bio-active glass particulate • 45% silica dioxide + 45% sodium oxide + 5% calcium + 5% phosphate • Osteoproductive and osteoconductive
  32. 32. POROUS POLYETHYLENE • For facial augmentation and to restore continuity to craniofacial skeletal defects • Straight chain aliphatic hydrocarbons • Non toxic, inert and stable • Ingrowth of bone and soft tissue rapid. • Small and medium defects • Pattern transferred to smooth surface. • Cut with knife • Soak in sterile saline at 180°F - to modify shape • Secure using titanium screws.
  33. 33. TITANIUM • • • • • • • Non corrosive Light weight Fatigue resistant Biocompatible Thermal expansion similar to bone Minimal fibrous encapsulation Non allergic / radiolucent
  34. 34. TANTALUM • • • • 0.38 mm thick Easy to reshape Expensive Radio opaque
  35. 35. OSTEOINDUCTIVE AGENTS • Bone morphogenic protein – Group of proteins extracted from the bone matrix that stimulate bone growth – Some are well-characterized biochemically and produced by recombinant DNA techniques – Wozney et al defined 7 BMPs – BMP 2 to 7 are related by amino acid homology and are members of TGF-β superfamily
  36. 36. • Combination of TGF-β 1, Natural coral skeleton and human fibrin glue • Rabbit skull
  37. 37. PAEDIATRIC PLASTY • • • • • • Not in less than 3 yrs Wait for 1 yr Auto bone preferred No alloplasty less than 8 yrs No split graft in infants Alloplasty – dislodges, retards growth
  38. 38. Methyl methacrylate • At least 5mm thick except over temporal region or in child. • Antibiotics • Scalp incision outside defect, never parallel to previous scar. • Avoid incising dura • Reflect temporalis
  39. 39. Split skull • Autograft of choice. • Either totally removed and then split or only outer table removed. • Along margin of defect outer table removed to create 5mm shelf. • Transfer to paper, avoid bone wax. • Donor---full thickness skull excised.
  40. 40. Rib and ilium • Sub periosteal excision of rib • Alternate ribs (never take >2 adjacent ribs) • Total length = A/W × 2 A - area of defect W - width of rib • Cut 4 mm longer than defect
  41. 41. Allogenic skull • • • • Human skull plates Demineralized powder Skull discs Resorption - 60 %
  42. 42. COMPLICATIONS • • • • • • Infection 1-8 % Granuloma, pneumatocele Erode skin Compression of brain and internal herniation Fracture and injure brain Donor site complications
  43. 43. Dead space morbidity • • • • • • Following planned plasty Children—obliterate spontaneously Adults - uncertain Microvascular free flap under plasty Mass effect, prolonged surgery Does not alter either external contour or protective function • Causes late infection
  44. 44. Infection • • • • • Auto -0-4 % Alloplasty -4 % MMA -1-4 % Avoidance - exclude connection with sinus Management - Antibiotics - Removal
  45. 45. Resorption • • • • Frozen and autoclaved Autoclaved Fresh Avoidance— – – – – Use membranous bone Avoid dessication Avoid boiling/autoclaving Stable fixation - 7-24 % - 10 % - 0-5 %
  46. 46. Migration • Less than 1 % • Avoidance - wire/mesh scaffolding, Rigid fixation • Management - Refixation
  47. 47. Hematoma • Avoidance – Hemostasis & Drain • Management – explore and evacuate if large
  48. 48. FUTURE • • • • Bone morphogenetic protein—BMP Recombinant BMP-2 - trial PDGF EGF, IGF – chemotaxis

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