Microsurgery in Hand Surgery

Microsurgery Basics & Tools - Tiny Titans Triumph

• Core Principles: High magnification, coaxial illumination, meticulous hemostasis, atraumatic tissue handling, stable operative field.
• Magnification:
  • Operating Microscope: Essential, provides 5x to 40x magnification.
  • Loupes: 2.5x to 8x magnification, for less critical dissection.
• Microinstruments: Specialized design for precision.
  • Needle holders (e.g., Castroviejo)
  • Forceps (e.g., Jeweler’s, Dumont)
  • Scissors (e.g., Vannas)
  • Vascular clamps (e.g., Acland, Yasargil)
• Suture Material: Fine, non-reactive monofilament (e.g., Nylon, Prolene), typically 8-0 to 12-0 gauge.
• Needles: Small, swaged, taper-point needles (e.g., BV series).

⭐ Successful microvascular anastomosis relies on the "no-touch" technique for the intima and precise suture placement, often 6-8 interrupted sutures for a 1mm vessel.

Microvascular Anastomosis - Stitching Streams

• Core Aim: Watertight, patent vessel union.
• Essentials: Magnification (microscope), fine instruments (e.g., Jeweler's forceps, Acland clamps), "no-touch" technique.
• Vessel Prep: Gentle adventitial stripping, lumen irrigation (heparinized saline).
• Suture: 9-0 to 11-0 monofilament nylon.
• Anastomotic Sequence:

• Patency Signs: Pulsatile flow, good capillary refill distal to anastomosis.

⭐ Thrombosis due to technical error is the primary cause of early failure in microvascular anastomosis.

Microneural Repair - Wiring Wonders

• Goal: Align fascicles for optimal axonal regeneration.
• Principles: Tension-free repair, atraumatic handling, meticulous hemostasis.
• Types of Repair:
  • Epineurial: Sutures through epineurium; most common.
  • Grouped Fascicular (Perineurial): Aligns specific fascicle groups; technically demanding.
• Suture Material: Monofilament nylon (e.g., 9-0 to 11-0).
• Timing: Primary (ideal, <24 hrs), delayed primary (days), or secondary repair (weeks; may need grafting).
• Nerve Grafts: Autografts (e.g., sural nerve) for gaps >2-3 cm.
• Prognosis Factors: Young age, distal injury, sharp transection, early repair.

⭐ Sunderland's classification (Grades I-V) guides prognosis and management of nerve injuries. Grade I (neurapraxia) has the best prognosis; Grade V (neurotmesis) the worst, requiring repair or grafting for recovery.

Free Flaps & Replantation - Patch & Reattach

• Free Flaps: Vascularized tissue transfer for complex defects.
  • Donor tissue (skin, muscle, bone) with artery/vein moved to recipient site.
  • Vessels anastomosed microsurgically.
  • Examples: Radial forearm, ALT, Gracilis (functional muscle).
  • Monitor: Color, temp, capillary refill, Doppler.

• Replantation: Reattachment of amputated parts.
  • Indications: Thumb, multiple digits, child (any part).
  • Warm ischemia limits: Muscle >6 hrs, Digit >12 hrs.
  • Cold ischemia (transport at 4°C): Muscle <12 hrs, Digit <24 hrs.
  • Repair Sequence (📌 BAVNTS): Bone → Artery → Vein → Nerve → Tendon → Skin.

⭐ Arterial repair is prioritized after bone stabilization in replantation to minimize ischemia.

High‑Yield Points - ⚡ Biggest Takeaways

• Microsurgery is essential for replantation, free tissue transfer, and intricate nerve repairs.
• Utilizes operating microscope, micro-instruments, and fine sutures (8-0 to 11-0 nylon).
• Vessel anastomosis (end-to-end) is critical; Acland clamps aid in temporary occlusion.
• Nerve repair techniques include epineural and fascicular coaptation; sural nerve is a common graft.
• Flap survival hinges on patent anastomoses and adequate perfusion.
• Allen's test is crucial pre-operatively to assess palmar arch patency for procedures involving radial or ulnar arteries.