Wound and Tendon Healing


Wound Healing

Healing by 1st Intention
Clean incised wound freshly sutured and heals without complication
Healing by 2nd Intention
Wound left open ® granulates, organises and eventually epithelialises ® contraction of the defect
Healing by 3rd Intention
Delayed closure, open wound ® decontaminated after which it is closed either directly, using steri strips or skin graft

Factors Affecting Wound Healing

1. Systemic

Hypoprotinaemia
Hypoxia and poor tissue perfusion
Deficiencies of Vitamin C & Zinc
Diabetes, Jaundice and Uraemia
Increasing age healing becomes less efficient

2. Local

Impaired local circulation
Infection and the presence of foreign bodies

3. Exogenous Chemicals

Corticosteroids
NSAIDs to a lesser extent
(Vitamin A reverses the effect of the above)
Oestrogen retards healing
Androgens promote healing

4. Physical Factors

Physical stress
Emotional stress

5. Surgical Factors

Poor tissue handling
Poor haemostasis
Avoid drains out through the wound
Post-operatively encourage early mobilisation
Acute inflammatory response ® appearance of macrophages
New blood vessels appear
Fibroblasts migrate to the wound ® lay down collagen whose disposition is determined by mechanical stress
Collagen synthesis and lysis occur in parallel
Ground substance is laid down and epithelialisation occurs
Wound contraction due to full thickness skin migrating towards the centre of the wound (healing by secondary intention)
Phase 1
Substrate phase or inflammatory response
Phase 2
Proliferative phase, collagen deposition ~ 3 - 14 days ® rapid increase in strength to about 75% of normal
Phase 3
Differentiation phase, continues for 6/12 or more, collagen remodelled along lines of stress until the wound strength approaches normal
Little to be gained by retention of sutures after 14 days in any site.

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Tendon Healing

A tendon consists of a central core (endotendon) made up of cellular longitudinal collagen fibres. A thin epitendon surrounds the central core, and this is then surrounded by a paratenon or a fibro osseous sheath such as the flexor pulley system of the hand.

Tendon Nutrition

Blood supply derived from the muscle belly, vinculae (long and short but only the long provides vascular supply) or the transverse vascular supply from the mesotendon
Diffusion of nutrients is probably a more significant pathway however

Physiology of Tendon Healing (2 theories)

1. Extrinsic Healing

One wound / one scar, ie healing occurs along the lines of secondary intention with a fibrovascular repair response originating from cells and vessels in the fibrous sheath, synovial lining and epitendon as well as subcutaneous and periosteal and bony tissue ® formation of tendon callus
Fibrous tissue joining the tendon and sheath is replaced by lining cells at ~ 6/52
Advocate gentle handling of the tendon and use of non reactive suture material
After treatment ® active movements at 4/52, no passive

2. Intrinsic Healing

Can occur in the absence of a fibrous sheath and synovial fluid medium. Cellular elements within epitendon and endotendon ® contribute to the repair process.
May involve early phagocytic process and later fibroblastic and collagen formation from epitendon and endotendon cells.
Under clinical circumstances particularly if the tendon is immobilised after repair the intrinsic response may be overwhelmed by an extrinsic response ® adhesions
Advocate windowing the sheath ® repair, use of non absorbable and non reactive suture material and early passive mobilisation
Animal and clinical evidence to support the use of early limited passive mobilisation in terms of improved strength of repair and digital function (Gelberman)
Tendon grafts ® should remove the peri tendon as if retained ® increased incidence of adhesions. Obtain nutrition by diffusion.

 



Burnell ® five tendon Zones

Zone 1
One tendon only (FDP) from middle of middle phalanx distally
Zone 2
Two tendons (FDS & FDP) from MCP joints to middle of middle phalanx
Zone 3
Central palm
Zone 4
Tendons in the carpal tunnel
Zone 5
Tendons proximal to the carpal tunnel

Kleinert method of rehabilitation following tendon repair

  1. Injury ® 3rd week splint wrist at 40-60o palmar flexion
    MCPs splinted in 60o flexion
    IPs splinted in neutral
    Active extension to splint with rubber band flexion
    No passive extension and no resisted flexion
  2. 5 1/2 - 6 weeks ® active flexion against mild resistance
    Gentle passive extension
  3. 10 weeks ® Dynamic splints for extension
    Progressive strengthening
    Joint jacks ® castings for flexion contractures
  4. 12 weeks ® resume full and normal activities
In children: Early motion or splintage for 3-4 weeks ® comparable results. Splinting > 4 weeks ® prejudicial influence on ultimate performance.
Prevention of Adhesions
  1. Avoid rough handling of tendon
  2. Use a core suture (Kessler, Burnell)
  3. Avoid primary repair in cases of severe trauma
  4. Make use of early passive mobilisation
  5. ? close tendon sheath (probably not important).


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