Tendon graft dnb ms question with answer

TENDON GRAFT

• used when tendon ends can not be approximated at the time of repair

Single stage tendon graft

• Indications
  • delay in repair, esp flexor tendons of hand (proximal end of tendon necrotic)
  • segmental lose of tendon ends
  • gap can not be closed because of myocontracture
• Pre requisites
• complete wound healing
• adequate soft tissue coverage
• absence of edema and induration
• skeletal alignment satisfactory and stable and full range of passive motion for all joints
• sensation normal or at least one digital nerve intact in fingers

• Contraindications
  • adherent extensor tendons
  • planned capsulotomy for stiff joints
  • need for pulley reconstruction

Two stage tendon graft

• I stage
  • excising the tendon ends and scar tissue from tendon bed
  • preserving the pulley system and reconstructing it if necessary
  • dacron impregnated silicone rod inserted to maintain the tunnel in area of excised tendons
• II stage
  • rod removed and tendon graft inserted
• Indications
  • severely scarred wound bed and bone exposure
  • simultaneous fracture fixation
  • both repair of flexor and extensor tendons
  • repair of A2 or A4 pulley
  • joint stiffness when capsulotomy planned
  • when local finger flap is needed
  • failed zone II tendon repair

Donor sites

• palmaris longus
  • easy access, no functional loss and good caliber for digit flexors
  • may be absent in 10% persons
• plantaris tendon
  • long tendon, no functional loss
  • can be easily braided if thicker graft is required
  • less accessible, absent in 20% persons
  • no test to determine its presence pre op
• extensor digitorum longus
• extensor indicis proprius
• flexor digitorum superficialis
• tendon grafts harvested from an irreparably injured structures

Tendon substitutes

• allograft
  • tendons contain minimal cellular elements- so less antigenicity – decreases the risk of fibrosis from immunologic reaction
• synthetic graft replacements
  • replacements made from dacron, expanded poly tetra fluro ethylene, carbon fibre, woven nylon
  • needed properties : biocompatibility, properties of the implant, ability to withstand repetitive stress, fixation of implant

Complications

• lumbrical plus finger
  • graft tension less – graft too long
  • seen in free tendon graft for FDP zone II injury
  • pull of profundus musculotendinous unit applied through lumbricals than flexor tendon graft – which is distal to lumbrical origin
  • pull on lumbricals cause extension of IP joints
  • gentle flexion – patient makes a fist
  • fast powerful flexion – IP joint extends in paradoxical extension
  • treatment : resection of involved lumbrical tendon
• quadriga effect
  • tendon graft too tight – increased tension
  • during flexion – grafted finger flexes more than other fingers and reaches palm first – limits the flexion ability of other fingers

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