Biogeometry of flaps.ppt
- 1. Biogeometry of Flaps Dr Raghav Shrotriya Department of Plastic Surgery KEM Hospital, Mumbai
- 2. FLAP • “A flap is a unit of tissue used for reconstruction that is transferred from one site (donor site) to another (recipient site) while maintaining whole or a part of its own blood supply”.
- 5. BIO-GEOMETRY • Definition : It is the integration and summation of biological and geometrical factors that govern the logic involved in efficient - selection, siting, design , construction and transfer of a surgical flap.
- 6. PLANNING OF LOCAL SKIN FLAP • 1- Assessment of tissue loss (true defect) • 2- Decide about reconstructive goals • 3- Planning of flap (Biogeometrical principles) • 4- Planning in reverse • 5- Execution
- 7. PEARLS • Prospective resection should not be compromised by a preconceived plan of reconstruction. • Treat the primary defect 1st ; Concern for secondary defect should not endanger final result • Always plan 10 to 20 % larger flap and review design after final debridement • Establish PIVOT POINT at the outset. • Elasticity-viewed only as an added insurance • Rule out any kink, twist or undue tension after inset of flap
- 9. Advancement flaps ❑ Local flap ❑ Advancement flaps have a linear or rectangular configuration. ❑ Moves linearly into the defect without lateral motion ❑ The movement is similar to that of a sliding door. ❑ Advancement flaps are sub-classified as • Simple / Islanded • Single pedicle • Bipedicle • V-Y / Y-V flaps
- 10. Advancement flaps- Biogeometry ❑ Donor source : Lax tissue that borders the defect ❑ Pedicle is at right angle to the base and directed at the defect. ❑ Width of the base equals that of the defect ❑ The ratio of defect length to that of the flap length should be 1:2, taking into account the altitude or the convexity of the surface.
- 11. Advancement flaps- Biogeometry ❑ Flap is raised by technique of ‘Progressive retropositioning’ of base ❑ Flap and the adjacent tissues must be undermined to facilitate the linear advancement. Without undermining, the flap and the pedicle could only be stretched and not advanced. ❑ Surgical effacement of the reclining cones that result due to approximation of the unequal wound edges become recognizable as the Triangle of Burow.
- 13. Techniques for effacements of reclining cones : 1. Employing the rule of halves while suturing (if the flap is long enough) 2. Excising the Burow’s triangles along the longer side 3. Bilateral Z plasties at the base of the flap (if the pedicle is wide enough) 4. Stark’s modification of advancement flap design (Pentographic Extension)
- 14. V-Y ADVANCEMENT Y-V or V-Y Adv. flap Tissue is advanced in direction of stem of Y at expense of sides Gain in length is perpendicular to stem of Y
- 15. Rotation Flaps • Semicircular flap, which is rotated around a pivot point till the defect is closed • Border of the defect becomes the advancing edge of the flap. • Similar to the effect that occurs along an axis of a revolving door. Flap rotates or moves into the defect in an arc of a circle
- 16. Biogeometry of Rotation flaps • Begins with depicted or actual triangulation of the defect. • Isosceles triangle with its apex C directed towards base or pedicle entry of flap. • Angle at C (between two long sides of the triangle) should be limited to around 30 degrees
- 17. Biogeometry of Rotation flaps • CD must be 50% longer than AC and midpoint of this line forms the centre of the arc with AE as the radius. • Point E can also be obtained by the addition of the long and short sides of the triangle (AC + AB) • Circumference is 5-8 times the width of the defect, can be extended till point D to facilitate rotation without compromising the base of the flap
- 19. Geometry of Back-cut • Back cut : To facilitate the sliding of the flap into the defect without tension, a back-cut is sometimes employed, 1. If circulation is beyond doubt, small cut is made along the diametrical line, which shifts the pivot point towards the centre of the arc reducing the tension.
- 20. Moving end of the flap moves twice the distance of back cut, which should be made equal to half the side of the triangular defect PQ = GH / 2 Secondary defect created due to opening up of back-cut is either closed by undermining of the surrounding skin or skin grafted. Geometry of Back-cut
- 22. 2. Triangular Excision: Cut is taken away from flap, tension line also develops away from the flap Geometry of Back-cut
- 23. • Increasing the size of the flap in relation to the defect helps reducing tension of the transfer. • The rotation flaps are a bit inefficient in the sense that a considerable amount of donor tissue needs to be recruited to cover a comparatively and disproportionately a small defect area.
- 24. Pearls • In scalp: rigidity and inextensibility, requires proper planning and back cut • In trunk: use of perforators for safety • In limbs : inclusion of investing layer of deep fascia adds to the safety of the local flap • Advantages : No secondary defect Distributes the tension over a long suture line away from the point of repair • Disadvantages : No tissue is added and repair relies on tissue elasticity and redundancy A large flap is required and can be geometrically applicable to close small defects only.
- 25. • A transposition flap is created so that the donor site is adjacent to the defect. The flap, whose advancing edge is shared by the defect margin, is moved about the pedicle and transposed over into the defect. • The transfer imparts an angular lateral (jackknife) action upon the pedicle. • Similar to that occurring at a hinge while opening or closing a door. Transposition Flap
- 26. • It is a rectangular / square flap located immediately adjacent to the defect and is moved laterally into the defect • Defect is triangulated into the shape of an isosceles triangle • One of the equal sides of the triangle acts also as a side of the flap
- 27. • Base is sited along the apex of the triangle • Pivot point is sited as a point on the extremity of the base most distant from the defect
- 28. Geometrical aspects • Triangulate with apex proximally and longitudinal side parallel to limb axis or along a blood vessel • Extend the chosen limb so that CP=CB
- 29. • On AP construct a square which is the required flap • Angle PCB is smoothed into a curve and the flap is transposed leaving a small dogear
- 30. • The side which is also part of the defect has to be made longer than the side of the triangulated defect so that the diagonal length of the flap before and the estimated diagonal length after transfer are at least equal
- 31. Pearls • Never mark out four sides, leave the base unmarked • Delay if previous scarring, surgical incisions or the surrounding defects make the vascularity questionable • Knowledge of vascularity and perforators is used wherever possible while planning
- 32. To recapitulate.. Flap Type Movement Similar to 1. Advancement Local Linear, without any lateral movement Sliding Door 2. Rotation Local Radial Arc Revolving Door 3. Transposition Local Lateral/ Angular Hinge Door
- 33. Transposition flaps with direct closure of the donor defect • In this second variety of transposition flaps, the flap passes across a ‘promontory’ of normal, undisturbed skin to gain into the primary defect • If the secondary defect is covered with an imported skin like a SSG, the same rules apply as in type 1, with pivot point and critical line playing identical roles as those described earlier. • If, however, the secondary defect is closed directly, other factors become important. The pivot point of such a flap must be sutured to the tip of promontory between the primary and the secondary defect
- 34. Transposition flaps with direct closure of the donor defect • To achieve this either the pivot point or the promontory or both must move. • The key to planning such a flap is to ensure that such approximation is possible. In this design of transposition flap, no stretch or tension occurs in the flap itself and the critical line is of no significance. • The most disciplined and geometric examples of these Type 2 transposition flaps are Limberg and Dufourmentel flaps.
- 36. Z plasty : • Z plasty is a variant of type 2 flaps, where flap and the promontory form transposition flaps • Definition : Procedure consisting of two identical triangular interdigitating flaps that transpose synchronously with each other recruiting tissue from one axis (transverse diagonal) and redistributing it along a perpendicular axis (contractural diagonal) resulting in length gain.
- 37. Z-plasty - ‘Converging triangular flap’
- 38. Z plasty
- 44. Interpolation flap • Interpolation flap is moved about the pedicle and transposed across intervening tissue; however the pedicle rests over the intervening tissue. • The pedicle must be divided and inset at a second stage after neovascularization occurs. Common interpolation flap is the forehead flap.
- 45. Limberg flap ↖ A rhombus is an equilateral parallelogram ↖ Rhomboid is a parallelogram in which the angles are oblique and adjacent sides are unequal
- 46. • It was first described by Alexander A. Limberg in 1963 • Limberg flap is used for rhombic defect with 60 ,120 degree angle. Limberg flap
- 47. Biogeometry of Limberg flap • Short diagonal of the rhombus defines the width of the flap • It is extended for an equal distance – DE=BD=AD=DC • A line is drawn from point E which is parallel to the side of the rhombus and of same length – EF=DE. • F is the pivot point and DE is the promontary
- 50. Dufourmentel Flap • Variation or modification of limberg flap • Dufourmentel flap is similar to limberg flap except that it can be constructed for a rhombic defect of any angle.
- 51. • Versatile flap - for defect that differs from rhombic, acute angles of variable degrees, • Diagonals are • Not perpendicular Not equal in length Not equal to arm of defect Dufourmentel Flap
- 54. Biogeometry of Dufourmentel flap • Defect is tailored to a rhomboid shape • Line AC and BC are extended to form GCH • Angle GCH is bisected by drawing a line CE • CE is equal to the side of defect
- 55. • EF is drawn which is parallel to BD • Again EF is equal to side of defect (AD = AB = BC = DC = CE = EF) • Now flap BCEF is raised and transposed to close the defect • To close a rhombic defect such 8 dufourmentel flaps can be raised. Biogeometry of Dufourmentel flap
- 56. BILOBED FLAP • The bilobed flap is a double transposition flap. • The primary flap is used to repair the surgical defect and a secondary flap is elevated to repair the original flap donor site • First described by ESSER in 1918 for reconstruction of nasal tip defects. • A total 180 degree transfer increased the trapdoor deformities and pincushioning
- 57. • In 1989, Zitelli emphasized on using a narrow angle of transfer, 45 degrees between each lobe • So the total transposition was 90-110 degrees • Complications were reduced • Disadvantages : Need of wide undermining of the skin surrounding the defect as well as flap and its donor site, most of the incisions necessary to elevate and transfer the flap produces scar that are not parallel to RSTL BILOBED FLAP
- 58. • Base can be laterally or medially as well • Ideal choice of defect is a defects of <=1.5cm situated on lateral nasal tip or side walls • Initially a burrow’s triangle is designed with its apex pointing laterally / towards the proposed base BILOBED FLAP
- 59. Biogeometry of Bilobed flap
- 60. Note Flap
- 61. Reading Man Flap
- 62. Final Thoughts • Be thoughtful. Consider all options, simple to complex, prior to any flap surgery. • Be knowledgeable. Know and understand the anatomy, blood supply, and quality of tissue available. A sound geometrical principle is essential along with knowledge of local tissue availability. • Be prepared for failure. Have several backup plans available if the first plan fails! • Rules can be bent, not broken
- 63. Acknowledgement • Dr Vinita Puri • Dr Mukund Jagannathan • Dr Vinay Jacob • Dr Ameya Bindu
- 64. THANK YOU