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aaaabbbb > 11 - Tendon Healing and Transfer > Flashcards

11 - Tendon Healing and Transfer Flashcards

1
Q

Introduction

A
  • Tendon transplantation redirects power while maintaining function and form
  • Does not create a new source of movement – utilizes the available power by eliminating less important motions and directing it to better advantage
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2
Q

Tendon transfer

A

o Detachment of a tendon of a functioning muscle at its insertion and then its relocation to a new insertion or attachment

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3
Q

Tendon transportation

A

o The rerouting of the course of a normal muscle tendon without detachment to assist other functions

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4
Q

Muscle-tendon transplantation

A

More of a plastics procedure
o The detachment of a muscle tendon at both its origin and its insertion and moving it to a new location along with its neurovascular support structures constitute a muscle–tendon transplantation

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5
Q

Tendon suspension

A

o Tendon procedures designed to support a structure (AKA tenosuspension)

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6
Q

Tendon histology

A
  • 30% collagen – makes tendon strong
  • 2% elastin – tendon does not rupture with little tension
  • Extracellular matrix 68% water
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7
Q

Tendon structure

A
  • Collagen fibril
  • Collagen fiber
  • Primary fiber bundle (sub-fascicle)
  • Secondary fiber bundle (fascicle)
  • Tertiary fiber bundle
  • Tendon
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8
Q

Epitenon

A

Synovial Layer, surround the tendon

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9
Q

Endotenon

A

surrounds primary, secondary and tertiary fiber bundles

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10
Q

Paratenon

A

Areolar tissue, continuous with epitenon contains nerve and blood vessels – straight

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11
Q

Mesotenon

A

Epitenon plus the paratenon

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12
Q

Tendon sheath

A
  • Tendon sheath is present when tendon angles around structures
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13
Q

Details of paratenon vs tendon sheath

A

Paratenon

  • Continuous with epitenon
  • Contains nerve and blood vessels
  • Allows tendon to glide
  • Only found on tendons with straight pull i.e. Achilles tendon

Tendon sheath

  • Tubular structure prevents bowstringing
  • Lined with synovial cells
  • Allows tendon to glide like a piston in a cylinder
  • Epitenon and inner layer of sheath make up mesotenon
  • Contains blood and lymphatics
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14
Q

Tendon anatomy - hilus and pilcae

A
  • Hilus = point of attachment in mesotenon
  • Plicae = connective tissue doubled over on itself to provide free pistoning motion of the tendon, stretching and folding to protect the vital mesotenon from excessive tension
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15
Q

VASCULAR SUPPLY

A

3 sources of vascular supply
o Musculotendinous junction (attachment to muscle)
o Bone/periosteum (attachment to bone)
o Paratenon by way of hilus (majority of supply)

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16
Q

Tendon attachment to bone

A
  • Tendon fans at insertion (especially for Achilles tendon)
  • Transitions from collagen –> fibrocartilage –> calcification as it inserts into the bone
  • Sharpey’s fibers (didn’t talk about)
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17
Q

Phases of tendon healing

A 
1 = impact (injury) 
2 = inflammatory 
3 = proliferative
4 = remodeling
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18
Q

Phase 1 = impact (injury)

A
  • Moment of injury activates complement cascade
  • Vasoconstriction, platelet aggregation (intrinsic and extrinsic pathway activation)
  • Chemotaxis (chemical stimulus response)
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19
Q

Phase 2 = inflammatory

A
  • Cellular infiltration with jelly-like serous and granulation tissue at gap zone
  • PMN’s and macrophages come to site of injury
  • Acidic environment with low oxygen tension stimulates fibroblast and collagen production
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20
Q

Phase 3 = proliferative

A
  • Fibroblasts bridge gap zone leading to collagen synthesis and eventual return of function
    o Collagen is in a disordered orientation at this point
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21
Q

Phase 4 = remodelling

A
  • Healing – systematic organization of collagen bundles with anatomic orientation
    o Here the collagen will reorganize for maximum strength/function
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22
Q

Tendon healing - week 1

A

Histology
- Softening, production of “jelly-like fibroblastic splint”

Strenght
- Comes from the sutures

Treatment
- Immobilization

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23
Q

Tendon healing - week 2

A

Histology
- Increased vascularity and proliferation of fibroblasts

Strength
- Suture

Treatment
- Immobilization

24
Q

Tendon healing - week 3

A

Histology
- Vigorous productions of collagen fibers

Strength
- Moderate bond strength

Treatment
- Gentle motion or isometric exercises

25
Q

Tendon healing - week 4

A

Histology

  • Collagen fiber alignmet
  • Cleavage from local tissues

Strength
- Gradual return to not quite full strength

Treatment
- Progressive muscular force

26
Q

Tendon healing - 3 months

A

Small collagen bundle formation with anatomic orientation

27
Q

Tendon healing - 4 months

A

Larger collagen bundle formation, normal tendon is restored

28
Q

Blix curve

A

Physiology of tension
- Blix determined that there is a certain muscle length at
which contractile force is strongest and most efficient
o Goal is to have your repair in this curve
o Don’t want muscle too short or too long
- Tension developed by muscle is related to length of the
muscle when it contracts
- **Muscle produces greatest force at 120% resting length
- **Zero tension is found to be at 60% resting length

29
Q

Physiologic tension

A
  • The tension of the muscle when it is completely relaxed – easy to assess under anesthetics in OR
  • When there is a rupture, there is no physiologic tension on the muscle or tendon
30
Q

Determining zero tension for transferred tendons

A
  • The foot is placed in the desired position for
    correction by dorsiflexing the foot to 90 degrees
  • Then all slack is removed from the tendon and
    it is fixed in place with 0 pounds of tension
31
Q

Tendon surgery forces and angles at the StJ

A
  • If you are trying to limit motion, get your tendon transfer as close to the joint axis as possible
  • If you want to rotate around the STJ axis, go 90 degrees from STJ, perpendicular to axis
  • If you want to stabilize, go parallel to bone, away from joint axis
  • If you want to rotate and stabilize, go halfway between – 45 degrees from joint axis
32
Q

Tendon fulcrum

A
  • Increases angle of application and improves efficiency of tendon function
  • Example:
    o Sesamoids within FHB tendon
    o Cuboid where peroneus longus passes
33
Q

Torque

A
  • Ratio of torque produced by anterior vs. posterior leg muscles in controlling foot function is 1:4
    o You have a lot stronger muscles in the posterior leg, weaker in front
  • This is due in large part to long lever arm of forefoot (weaker) vs. the short lever arm of triceps surae (stronger)
34
Q

Tendon surgery (phase function)

A

Extensor muscles are all swing phase muscles
o This makes it difficult if you want to transfer an extensor for a flexor - It is still possible, it takes some retraining of muscles – goal is regaining function
o Muscles: tibialis anterior, EHL, EDL, peroneus tertius

Remaining muscles are all stance phase muscles
o Muscles transferred “in phase” take 7 to 8 weeks to regain activity (requires less PT)

35
Q

Principles of tendon transfer

A

Improve motor function #1 goal
o Tendon transfers are typically done to regain function
o Most common tendon transfer is for pes cavus, commonly due to neuro deficits seen with Charcot Marie Tooth (lose muscle function in anterior and lateral muscle groups)

Other goals

  • Eliminate deforming forces
  • Restore lost motor function
  • Increase stability
  • Eliminate need for bracing
  • Improve cosmetic appearance
36
Q

Grading system for manual muscle testing

A

Grade 5 = normal, full resistance at end range of motion

Grade 4 = good, some resistance at end range of motion

Grade 4 + = moderate resistance at end range of motion

Grade 4 - = mild resistance at end range of motion

Grade 3 = fair, able to move against gravity alone

Grade 2 = poor, able to move with gravity eliminated

Grade 1 = trace, can palpate or visualize muscle contraction

Grade 0 = no evidence of muscle contraction

37
Q

Tendon transfer muscle testing

A
  • Make sure you are testing the tendon you are transferring for adequate strength
  • You will lose 1 muscle grade withthe transfer, so it needs to be strong initially (3/4- is NOT strong enough)
  • Fasten tendon under zero tension
38
Q

Zero tension

A
  • You want a LACK of tension in the tendon when the foot

is in the position of maximum contraction of the muscle

39
Q

Providing direct or mechanically efficient line of pull

A
  • The arrows indicate the relative direction and amount
    of force of tendons transposed at different levels
  • A more proximal transfer of the insertion enhances
    available dorsiflexory power
  • With a more distal insertion, the line of pull tends
    to parallel the lever arm and the mechanical
    advantage of dorsiflexion is lost
40
Q

Tendon fixation types

A
  • Side to side anastomosis
  • End to end
  • Tendon to bone
41
Q

Side to side anastomosis

A
  • Most physiologic pull
  • Problem is slippage, so cross-hatch or rough up tendons to promote fibrous union
  • Need to suture really well or you will get slippage
42
Q

End to end

A

There are 4 different suturing types that can be used for this type

  1. Bunnell (“crisscross through entire tendon”)
    o Most common end to end suture repair
    o Moderate strength, pull is longitudinal
    o Disadvantage: constricts vascular supply to tendon (due to crisscross orientation)
  2. Lateral Trap
    o Designed after Chinese finger trap - grips outside of tendon
    o Avoids constricting microcirculation
  3. Kessler
  4. Krackow –> most common for Achilles tendon repair
    o Interlocking weave stitch
    o Good tensile strength, doesn’t constrict microcirculation, technically easy to perform
43
Q

Tendon bone repair purpose

A

o If you are removing tendon from bone, you need a way to get the tendon back down and attached to the bone - many ways to do this

44
Q

Trephine plug

A

o You can create a bone hole, put the tendon in, then put the bone plug back in there

45
Q

Interference screw

A

o Drill a hole that is a little larger, put the tendon in, then use a ridged edge screw to hold the tendon in the hole (there are ridged edges that hold the tendon down)

46
Q

Button anchor

A

o Tendon anchors into bone using an external “button” on the outside of the skin for a few weeks until there is good bone and tendon healing – gives good tension

47
Q

Three hole suture

A

o Drill a hole then a smaller hole so you can pull the suture out the smaller hole

48
Q

Screw and washer

A

o “Old school” detach tendon, reattach elsewhere, shoving tendon in hole then putting screw and washer to anchor it in there

49
Q

Suture anchor

A

o Tack it to outside of bone, do suture anchors into the area, suture on the outside
o Suture needles allow you to suture tendon to the bone

50
Q

Tendon lengthening

A
  • “Z” tendon lengthening, allows tendon to slide on itself

- Commonly used in EDL for contracted digits

51
Q

Tendon augmentation products

A

Makes the tendon LONGER and STRONGER

  • You can use one of these products if you don’t have enough length or the repair is not very good due to a weak/measly tendon (you can wrap one of these around tendon to strengthen it)
  • The problem is that you then get a “bulky tendon” repair
  • Products: Graft Jacket, Restore, Pegasus, Cadaveric graft
52
Q

Split FDL transfer for contracted digit

A

o For hammer toe repair

o You can resect out the joint, split FDL in half then wrap it around the toe to hold it down

53
Q

FHL transfer for Achilles repair

A

o If you have a rupture, you can do a FHL transfer
o Easy to harvest then drill through bone or anchor it down to the bone to augment repair
o Restores plantar flexor action

54
Q

Jones Tenosuspension

A

o In the case of a plantarflexed 1st metatarsal, you can detach extensor tendon and reattach in midfoot to release tension
o Same as Hibbs, just for the 1st metatarsal and not the lesser digits

55
Q

Hibbs tenosuspension

A

o Used in FLEXIBLE pes cavus deformity - Toes stick straight up while non-WB, flat while WB
o Take extensor longus tendons to each of the lesser digits, cut them, then reattach them in a bundle to the midfoot to release the “pull” on the toes so they lay flat
o Since it was reattached to midfoot, it still has dorsiflexory power
o Toes still have extension function because of extensor digitorum brevis
o Sometimes done in conjunction with Jones (for hallux relaxation as well)

56
Q
  • Posterior tibial tendon transfer
A

o Used in patients with severe DROP FOOT (neuro, congenital, genetic neuromuscular, trauma or other etiology)
o In drop foot, the posterior tibial tendon is over firing and is the only one working, so it is overpowering the dorsiflexors (no dorsiflexion is occurring)
o Harvest at insertion site, transfer it to have a dorsiflexion function by pulling it though the tibial-fibular interosseous membrane

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