Principles of Tendon & Ligament Injury and Repair

Question 1

what is the function of tendons?

Answer 1

• transmit forces between muscle and bone, mainly tensile
• concentrate muscle forces + allow directional changes
• store energy and proprioception

Question 2

what is the best disney princess movie

Answer 2

sleeping beauty

Question 3

what is the best movie ever made

Answer 3

steel magnolias

Question 4

what is the main component of the collagen in the extracellular matrix?

Answer 4

type 1 collagen! 98%

Question 5

what is the fibrocartilagenous region of a tendon?

Answer 5

collagen type II, large protoeoglycans, reflects ability to cope with compressive load

Question 6

describe the blood supply to tendons**

Answer 6

• relatively avascular: 2-4% oxygen is normoxic for healthy tendon in vivo
• blood supply and thus ability to heal is affected by age, exercise, injury

Question 7

T/F: tendons have a similar blood supply to bone

Answer 7

FALSE tendons are relatively avascular: 2-4% oxygen normal

Question 8

blood supply and thus ability to heal of tendons is affected by what 3 factors? **

Answer 8

1. age: higher in foals, gradual decline in blood flow to adult level by 3 years of age
2. exercise: training induced increased blood flow (200%)
3. injury: blood flow elevated in affected & contralateral limbs (300%)

Question 9

what type of collagen are tendons and ligaments made up of?

Answer 9

tendons: type 1
ligaments: type 3

Question 9

viscoelastic properties of tendons/ligaments

Answer 9

1. stress: force/area
2. strain: change in length/original length
3. stiffness: load divided by deformation

Question 10

how does anatomy relate to resolution of injuries?**

Answer 10

• tendon heals SLOWLY = low blood supply!
• healed tendon lacks elasticity and strength compared to healthy tendon
• high incidence of recurrent injuries from impaired elasticity/strength: increased collagen 3 vs 1 content, reduced strength of scar tissue

Question 10

T/F: a healed tendon has less elasticity/strength than a healthy tendon

Answer 10

true

Question 11

what is an extrinsic tendon injury?

Answer 11

• percutaneous laceration or blunt trauma
• most serious when palmar/plantar metacarpal or phalangeal region: up to 50% tendon can be lacerated and still provide full walk fx

Question 12

when is an extrinsic tendon injury most serious? (think anatomic region)

Answer 12

palmar/plantar metacarpal or phalangeal region

Question 13

what is an intrinsic tendon injury?

Answer 13

• biomechanical overload/strain
• altered hoof conformation
• very hard or soft ground
• shoeing
• horse speed
• end performance muscular fatigue

Question 14

what are contributing factors to tendon injury?**

Answer 14

1. conformation
2. shoeing
3. fatigue related incoordination during performance
4. aging
5. exercise

Question 15

what are predispositions in tendon injury?**

Answer 15

1. flexor tendons > extensors
2. SDFT > DDFT: more external, smaller surface area, less vascular midcarpal region
3. forelimbs > hindlimbs

Question 16

are flexor or extensor tendons more predisposed to injury?

Answer 16

flexor

Question 17

is SDFT or DDFT more likely to be injured?

Answer 17

SDFT

Question 18

are forelimbs or hindlimbs more predisposed to tendon injury?

Answer 18

forelimbs

Question 19

what is the earliest and most subtle sign of tendon/ligament injury?

Answer 19

heat

Question 20

how do you diagnose tendon/ligament injuries?

Answer 20

1. physical examination
2. musculoskeletal palpation: heat, pain, swelling/bow
3. lameness of affected limb
4. ultrasound: echogenic score 1-4
5. radiograph: desmitis, evaluate sesamoid and splint bones
6. nuclear scintigraphy: picks up areas of increased bone turnover

Question 21

tendonitis

Answer 21

inflammation of tendon and tendon-muscle attachments

Question 22

tendosynovitis

Answer 22

inflammation of tendon and tendon-muscle attachments within tendon sheath

Question 23

tenosynovitis

Answer 23

inflammation of tendon sheath alone

Question 24

desmitis

Answer 24

ligament inflammation

Question 25

T/F: laceration involving digital flexor tendon sheath is considered a life-threatening emergency

Answer 25

true: stabilize horse and limb before moving further. flexor tendons: dorsal splint (Kimzey)

Question 26

what do you see when the SDFT alone is lacerated?****

Answer 26

mild hyperextension

Question 27

what do you see when the SDFT and DDFT are lacerated?****

Answer 27

moderate hyperextension and elevation of toe off ground

Question 28

what do you see when SDFT, DDFT and suspensory ligament are lacerated?****

Answer 28

complete loss of fetlock join support

Question 29

how do you approach tendon lacerations involving synovial structure?

Answer 29

- life threatening! emerg - synoviocentesis of synovial structure - synovial arthoscopic lavage and debridement - abx therapy - injection? coaptation?

Question 30

stages of tendon healing

Answer 30

1. acute inflammatory phase: 1-2 weeks 2. subacute reparative/fibroblastic phase: 2-28d 3. remodeling phase: 60days-18 months

Question 31

acute inflammatory stage

Answer 31

- hemorrhage - edema - fibrin accumulation - local swelling - increased risk reinjury!

Question 32

subacute reparative/fibroblastic phase

Answer 32

- several days after injury onset, overlaps w inflamm phase - strong angiogenic response, fibroblasts, scar tissue formation! - scar tissue composition different from tendon: higher collagen 3 content

Question 33

maturation/remodeling phase

Answer 33

- fibroblasts make type 1 collagen - collagen bundles orient along lines of stress - vascularity and cellularity decreased

Question 34

treatment for tendon/ligament injuries?

Answer 34

- surgical vs medical - phase of disease: acute, subacute, chronic

Question 35

flexor tendon laceration approach ****

Answer 35

1. debride vs suture tendon closed? 2. suture patterns: 3 loop pulley vs interlocking loop 3. distal limb cast 6-8 weeks 4. 55% return to athletic function

Question 36

compare suture patterns used to fix flexor tendon lacerations****

Answer 36

1. three loop pulley: - prevents distraction tendon ends 2. interlocking loop: - little suture left outside tendon: used for intrathecal tendon repair (within tendon sheath) - not as strong as 3 loop pulley

Question 37

what suture approach is stronger for flexor tendon lacerations: 3 loop pulley or interlocking?****

Answer 37

three loop pulley

Question 38

how long do flexor tendon lacerations need to be in a cast

Answer 38

6-8 weeks

Question 39

what has a better return to athleticism: flexor or extensor tendon injuries?

Answer 39

extensors: 70-80% return flexors: 55% return

Question 40

approach to extensor tendon lacerations

Answer 40

- debride and close - splint bandage or cast if knuckling - exercise confinement 4-6 weeks - complications: granulation tissue, sequestrum formation

Question 41

physical treatments for tendon/ligament injuries

Answer 41

- cold therapy - compression/coaptation - shoeing - controlled exercise - shockwave therapy - US - low level laser therapy

Question 42

pharmacologic treatments for tendon/ligament injuries

Answer 42

- systemic: NSAIDs, corticosteroids - intralesional: hyaluronan, corticosteroids, biologics

Question 43

what biological therapies can be used with tendon/ligament injuries?

Answer 43

- bone marrow/adipose mesenchymal stromal cells - autologous conditioned serum - bone marrow aspirate concentrate - platelet rich plasma

Question 44

acute stage care

Answer 44

1. exercise confinement 2. minimize inflammation 3. support tendon/ligament

Question 45

subacute stage care

Answer 45

1. controlled exercise: aligns collagen fibers, walking swimming 2. ultrasounds

Question 46

chronic stage care

Answer 46

1. rehab exercises 2. tendon splitting? 3. counter-irritation "firing" or "blistering" SHOULD BE ABANDONED