By Dr. Sachin. M, Junior resident, Dept of Orthopaedics, SMCH, Silchar.

1. BASIC PRINCIPLE
AND TECHNIQUES OF
MICROSURGERY
P R E S E N T E D BY : D R . S A C H I N . M .
P G T, D E P T O F O R T H O PA E D I C S , S M C H
M O D E R ATO R : D R . A N S H U M A N D U T TA
A S S O C I AT E P R O F E S S O R , D E P T O F O R T H O PA E D I C S , S M C H

2. LEARNING OBJECTIVES
• Introduction
• Blood supply of skin, Concept of angiosome
• Flaps
– Definition
– Classification
– Indications and contraindications
– Technical approach
– Complications
• Vascular repair
• Nerve repair

3. INTRODUCTION
• Microsurgery is the most sophisticated part of reconstruction surgery which
requires an operating microscope to deal with microstructures like vessels,
nerves etc.
• Sushruta – Father of Plastic surgery
• Sir Harold Gilles – Father of modern plastic surgery
• Requires lot of training – steep learning curve
• Requires operating microscope, microsurgical instruments.

4. BLOOD SUPPLY OF SKIN

5. BLOOD SUPPLY OF SKIN

6. CONCEPT OF ANGIOSOME
• Introduced by Taylor and Palmer
• Each angiosome is a three dimensional unit of skin, subcutaneous tissue,
muscle and bone, supplied by a single vessel, which in turn connects with
adjacent angiosome through choked vessels
• Each angiosome depends on a single named vessel

7. CONCEPT OF ANGIOSOME
• Introduced by Taylor and Palmer

8. FLAPS
• Definition: tongue of tissue containing various kind of tissues which carries
all its own blood supply, which either remains attached to the body at all
times or detached from the body temporarily, for its nourishment.
• Pedicle flap – remains attached to the body at all times
OR
• Free flap – requires reconstruction of vasculature

9. CLASSIFICATION OF FLAPS
• BASED ON RELATION OF DONOR TO RECIPIENT SITE
RELATION OF DONOR TO
RECIPIENT SITE
LOCAL FLAPS
Eg: one leg to same
leg
REGIONAL FLAPS
Eg: One leg to same side
foot
DISTANT FLAPS
DISTANT PEDICLE FLAP
Eg: one leg to another leg with
pedicle attached to the donor leg
DISTANT FREE FLAP
Eg: one limb to another limb
with anastomosis of nutrient
vessels

10. CLASSIFICATION OF FLAPS
TYPE OF MOVEMENT OF FLAP
ROTATIONAL ADVANCEMENT FLAPS TRANSPOSITIONAL FLAPS
- Pivotal flap
- More the pivoting,
lesser will be the
effective length of
flap
- More the pivoting,
more the chances
of formation of dog
ears or standing
cones
- Rectangular flap is made
right next to the defect
area
- Flap is advanced over the
defect by using the laxity of
local skin
- Pivotal flap
- Flaps are constructed at a
distance from the defect
- Aka Interpolation flaps

11. CLASSIFICATION OF FLAPS

12. CLASSIFICATION OF FLAPS
• BASED ON VASCULAR SOURCE AND PATTERN
• Random pattern flaps – source of blood not known
– Aka Local cutaneous flap
– Survival length of flap depends on perfusion pressure of the vessels in
the flap
– 1:1 in extremities and 3 to 4:1 in head and neck
– Receives blood from all the sources

13. CLASSIFICATION OF FLAPS
• BASED ON VASCULAR SOURCE AND PATTERN
• True axial pattern flaps
– Flap of skin and SC tissue that includes a direct cutaneous vessel with
accompanying venous drainage, which runs parallel to the long axis of
the flap
– Flap will be longer with narrow width pedicle

14. DELAY PROCEDURE
• Done to improve the length to breadth ratio of the flap
• To improve the chances of complete survival of all flaps
Gradually decreases the blood supply of the flap over a period of
few days to weeks
Acclimatization OR Orientation of blood vessels due to gradual
ischemia
(Initial vasospasm followed by vasodilation and hypertrophy of
intima)
Vasodilation occurs till size of flap vessels and choke vessels match
Large flaps can be constructed with higher survival
chances of the flaps

15. DELAY PROCEDURE

16. CLASSIFICATION OF FLAPS
• BASED ON COMPOSITION OF FLAP / TISSUE TYPES
– Skin and subcutaneous tissue
– Fasciocutaneous flap – includes deep fascia
– Myo / musculocutaneous flap – includes muscle
– Osseocutaneous flaps – includes bone
– Muscular flaps – only muscle
– Osseous flap – only bone
– Neurocutaneous flap – intact nerve supply
– Omentum / part of small bowel

17. CLASSIFICATION OF FLAPS
• MYOCUTANEOUS FLAPS – Mathes and Nahai classification
– Type I: single pedicle
– Type II: one dominant + one minor pedicle
– Type III: two dominant pedicles
– Type IV: multiple segmental pedicles
– Type V: one dominant + multiple segmental pedicles

18. CLASSIFICATION OF FLAPS
• FASCIOCUTANEOUS FLAPS – Cormack and Lamberty classification
• Type A: depends on multiple unnamed fasciocutaneous vessels
• Type B: one large and consistent vessel among all the unnamed
fasciocutaneous flaps
• Type C: based on multiple perforator vessels arising from one main artery
• Type D: Type C with inclusion of bone, osseo-myo-fascio-cutaneous flaps
• Advantages:
– No need to sacrifice the muscle – no loss of function or contour
– Need lesser dissection, lesser risk of injury to underlying neurovascular
structures

19. CLASSIFICATION OF FLAPS

20. CLASSIFICATION OF FLAPS
• ISLAND FLAP
• In axial pattern flap, nutrient vessels in the pedicle can be skeletonized so
that the flap is attached to the body only by its vascular pedicle
• PERFORATOR FLAPS
• They include only the exact amount of tissue with its immediate vascular pedicle
• No damage is incurred to the adjacent tissue for the sake of providing vascular
supply to the flap – least donor site morbidity
• Thin, pliable and moldable – excellent wound coverage

21. CLASSIFICATION OF FLAPS
ISLAND FLAP PERFORATOR FLAPS

22. CLASSIFICATION OF FLAPS
• PROPELLER FLAPS: islanded
fasciocutaneous flaps
• CROSS-LEG FLAPS:
• Advantages
– donor site is away from loco-
regional scarring and zone of trauma
– possible in the setting of non-
availability of microvascular
facilities
• Disadvantages – joint stiffness
- prolonged hospital

23. INDICATIONS
• Closure of wounds over the exposed bones, joints, cartilage, denuded
tendons and poorly vascularized wound bed
• In chronic osteomyelitis – muscle flaps
• Reconstruction of sole defects
• Reconstruction of bone defects – vascularized bone graft
• Padding in fingertip injuries and pressure sores
• Thumb reconstruction
• Innervated skin flaps – to restore sensation
• Restoration of circulation to distal extremity in case of vascular compromise
• Functional muscle transfer
• Coverage of exposed vessel – to avoid vessel blowout

24. CONTRAINDICATIONS
PATIENT FACTORS
• General health condition of the
patient like nutrition, anemia,
hypoproteinemia
• Comorbid conditions like DM,
HTN, cardiovascular disorders,
Raynaud syndrome, Collagen
vascular diseases
• Ongoing infections
• Radiation
• Smoking
• Uncontrolled coagulopathy
SURGICAL FACTORS
• Lack of well-trained surgeons /
surgical team
• Lack of operating microscope
• Lack of microsurgical
instruments
• Lack of facilities for efficient
post-operative care of the
patient

25. TECHNICAL APPROACH
• INVESTIGATIONS
• Laboratory – Routine blood, coagulation panel, ABO and Rh typing, ECG,
CXR
• Imaging studies: X-ray of the involved part, 3D CT scan, Lower extremity
angiography
• EQUIPMENTS REQUIRED
• Operating microscope
• Microsurgical instruments
• Microsutures (8-0 to 11-0 nylon)
• Vein coupler
• Sterile Doppler device

26. TECHNICAL APPROACH
• APPROACH TO THE PATIENT AND SURGERY
• Prolonged duration of surgery >8hrs
• Informed written consent from the patient and the family
• Preoperative planning, with a BACKUP PLAN
• Recipient vessel should be planned outside the zone of injury
• Discuss the plan among surgical teams, scrub nurses and anesthesiologists

27. PRINCIPLES OF TECHNIQUE
• PREPARATION OF RECIPIENT SITE
– Resect the tumor / diseased area
– Control of infection and thorough debridement
• DOPPLER USG: localization of the recipient vessel
• CHOICE OF OPTIMAL FLAP
– Size of the defect
– Type of tissue required for repair
– Length of the vascular pedicle
– Reliability of the flap

28. PRINCIPLES OF TECHNIQUE
• MICROSURGICAL ANASTOMOSIS
• FINAL INSET OF THE FLAP
• FINAL ASSESSMENT OF THE FLAP VIABILITY
– Clinical assessment
– Doppler assessment
• LOOSE DRESSING WITH PORTION OF FLAP EXPOSED FOR POST-OP
MONITORING

29. POST-OP MONITORING
• Initially, done every hourly, gradually increasing the interval of assessment
• Earlier the recognition of flap vascular compromise and its immediate
rectification, higher the chances of its successful salvage
• Clinical assessment:
– Extremely pale flap: arterial insufficiency
– Congested blue flap: venous obstruction
– Warmth and capillary refill
– Prick with hypodermic needle: look for bleed and its color

30. POST-OP MONITORING
• Objective tests
– Transcutaneous oxygen monitoring (pO2), pH monitoring
– Doppler ultrasound
– Laser Doppler flowmetry
– Microdialysis
– Surface temperature probes
– Injection of fluorescein dye

31. COMPLICATIONS
• INTRAOPERATIVE
– Due to altered vascular anatomy
– Inadvertent separation of components of the flap
– Inadvertent separation of the pedicle
– Inadequate blood supply due to very small perforators
– Inadequate venous drainage – congestion
– Failure of vascular anastomosis in free flaps

32. COMPLICATIONS
• POSTOPERATIVE
• Sutures under tension: due to smaller flap size
– Prompt removal of few stitches will relieve the tension, otherwise flap necrosis
occurs
• Hematoma formation: due to poor hemostasis or use of anticoagulants
– Evacuate and prevent further hematoma formation
• Seroma formation: due to malfunctioning of drain or its premature removal
– Drain the seroma

33. COMPLICATIONS
• POSTOPERATIVE
• Vascular compromise
– Faulty patient position
– Compressive dressings
– Blockage due to thrombus / venous stasis
– Kinking or twisting of the vessels
• Infection
• Wound breakdown
• Systemic complications of anesthesia
• DVT and pulmonary embolism

34. COMPLICATIONS
• LONG TERM COMPLICATIONS
• Aesthetics: bulky flap; biscuit or cookie appearance of flap
• Difference in hair growth and color pattern at recipient site
• Donor site morbidity:
– Hypertrophic scar
– Contour defects
– Difference in hair growth

35. MICROVASCULAR ANASTOMOSIS
• PREOP PREPARATION
• Pharmacological agents: 1% lidocaine, papeverine
• Vessel dilators
• Approximate clamps
• Monofilament nylon (8-0 to 11-0) with 75micron
needle
• Bipolar cautery

36. MICROVASCULAR ANASTOMOSIS
• Resection of vascular wall until the cut ends appear normal
• Mobilization of both ends of vessel to obtain adequate length for
anastomosis
– Approximate the ends with minimal tension
– Colored plastic sheet is placed beneath the Bessel to make it easier to see
• Cauterize the side branches
• Irrigate with heparinized RL solution intermittently
– Clear blood clots by jet of saline

37. MICROVASCULAR ANASTOMOSIS
• Vessel dilation: up to 1.5 times the normal
– Pharmacological agents (1% lidocaine)
– Mechanical dilation: may injure the intimal layer
• Approximate clamps – 2 atraumatic clamps with rectangular frame
– Clamp the vessels with minimal effective pressure
– Pressure >30gm/sq.mm. may damage the endothelium, leading to thrombus
formation
• Removal of adventia from the vessel wall up to 2mm from the vessel wal
– Avoids incorporation of adventia in suture
• Anticoagulation – systemic heparin

38. MICROVASCULAR ANASTOMOSIS
• SUTURE TECHNIQUE
– Inside out sutures: Use double armed suture to insert needle from inside out on
both sides
– Interrupted sutures – prevent vascular constriction
– Avoid suturing both walls together
– Place 2 sutures approximately 120o apart so that posterior wall falls away and
making it less likely to stitch both walls
– Rotate clamp approximator to expose the posterior wall and place the 3rd stitch
120o apart from first 2 stitches
– Place more stitches in remaining spaces to complete the anastomosis
– 1 mm artery requires 5 to 8 stitches
– 1 mm vein requires 7 to 10 stitches

39. MICROVASCULAR ANASTOMOSIS
• 2 methods of vascular anastomosis
• End-to-end anastomosis
• End-to-side anastomosis

40. MICROVASCULAR ANASTOMOSIS
• COMPLETION OF ANASTOMOSIS
• First remove distal clamp and look for back filling in the vessel across the
suture line
• Remove proximal clamp
• Clamp vessel distal to the anastomosis to check the patency of the
anastomosis
• If leakage +, place additional sutures
• COMPLETION ARTERIOGRAM
• To assess quality of reconstruction
• Look for intimal defects, suture line problems and adequacy of the distal
run-off

41. MICROVASCULAR ANASTOMOSIS
• VASCULAR GRAFT OR SHUNTS
• To be used when tension in sutures is expected
• In general, 1 to 2cm of artery may be resected without graft replacement
• Eg: Saphenous bypass graft, prosthetic conduits

42. NERVE INJURY – SUNDERLAND TYPES
TYPE LEVEL OF INJURY WALLERIAN
DEGENERATION
REVOVERY /
SURGERY
SEDDON TYPE
1
(least severe)
Myelin sheath Not seen Spontaneous full
recovery
Neuropraxia
2 Axons Seen Spontaneous full
recovery
Axonotmesis
3 Endoneurium Seen Surgical repair Axonotmesis
4 Perineurium Seen Surgical repair Axonotmesis
5
(most severe)
Epineurium with
complete disruption of
nerve
Seen Surgical repair Neurotmesis

43. NERVE REPAIR
• PRIMARY REPAIR
• Done in a clean sharp cut nerve injury
• Should be performed within 7 days of injury
• Age of the patient is the single most factor in sensory recovery after nerve
repair
• Adversely affected by associated injuries to the muscles, tendons and bones
• ADVANTAGES
• Lack of scarring
• Minimal dissection
• Facilitation of recovery of motor function

44. NERVE REPAIR
• SECONDARY REPAIR
• Done in Gunshot wounds leading to nerve division
• Avulsion injuries
• Grossly contaminated injuries
• Procedure includes
• Initial debridement with resection of nerve ends
• Place the sutures at the nerve ends
• Control infection
• Definitive repair once wound is healthy

45. NERVE REPAIR TECHNIQUE
• EPINEURAL REPAIR
• Most commonly done – sutures are placed in the epineurium
• GROUP FASCICULAR REPAIR
• Each fascicles are tried to be aligned: motor to motor, sensory to sensory
• Increased need for nerve manipulation to achieve fascicular alignment
• Chances of aligning incorrect fascicles
• Nerve repair should be tension free to such an extent that it allows patient
to perform physiotherapy after a brief period of immobilization

46. NERVE REPAIR TECHNIQUE

47. NERVE REPAIR TECHNIQUE
• NERVE GRAFTS
– For nerve defects of > 1cm
– When nerve repair under tension
is expected
– Sural nerve is the most common
donor nerve
– Medial and lateral antebrachial
cutaneous nerve are the other
sources

48. THANK YOU