Principles of Tendon & Ligament Injury and Repair Flashcards
what is the function of tendons?
- transmit forces between muscle and bone, mainly tensile
- concentrate muscle forces + allow directional changes
- store energy and proprioception
what is the best disney princess movie
sleeping beauty
what is the best movie ever made
steel magnolias
what is the main component of the collagen in the extracellular matrix?
type 1 collagen! 98%
what is the fibrocartilagenous region of a tendon?
collagen type II, large protoeoglycans, reflects ability to cope with compressive load
describe the blood supply to tendons**
- 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
T/F: tendons have a similar blood supply to bone
FALSE tendons are relatively avascular: 2-4% oxygen normal
blood supply and thus ability to heal of tendons is affected by what 3 factors? **
- age: higher in foals, gradual decline in blood flow to adult level by 3 years of age
- exercise: training induced increased blood flow (200%)
- injury: blood flow elevated in affected & contralateral limbs (300%)
what type of collagen are tendons and ligaments made up of?
tendons: type 1
ligaments: type 3
viscoelastic properties of tendons/ligaments
- stress: force/area
- strain: change in length/original length
- stiffness: load divided by deformation
how does anatomy relate to resolution of injuries?**
- 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
T/F: a healed tendon has less elasticity/strength than a healthy tendon
true
what is an extrinsic tendon injury?
- 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
when is an extrinsic tendon injury most serious? (think anatomic region)
palmar/plantar metacarpal or phalangeal region
what is an intrinsic tendon injury?
- biomechanical overload/strain
- altered hoof conformation
- very hard or soft ground
- shoeing
- horse speed
- end performance muscular fatigue
what are contributing factors to tendon injury?**
- conformation
- shoeing
- fatigue related incoordination during performance
- aging
- exercise
what are predispositions in tendon injury?**
- flexor tendons > extensors
- SDFT > DDFT: more external, smaller surface area, less vascular midcarpal region
- forelimbs > hindlimbs
are flexor or extensor tendons more predisposed to injury?
flexor
is SDFT or DDFT more likely to be injured?
SDFT
are forelimbs or hindlimbs more predisposed to tendon injury?
forelimbs
what is the earliest and most subtle sign of tendon/ligament injury?
heat
how do you diagnose tendon/ligament injuries?
- physical examination
- musculoskeletal palpation: heat, pain, swelling/bow
- lameness of affected limb
- ultrasound: echogenic score 1-4
- radiograph: desmitis, evaluate sesamoid and splint bones
- nuclear scintigraphy: picks up areas of increased bone turnover
tendonitis
inflammation of tendon and tendon-muscle attachments
tendosynovitis
inflammation of tendon and tendon-muscle attachments within tendon sheath
tenosynovitis
inflammation of tendon sheath alone
desmitis
ligament inflammation
T/F: laceration involving digital flexor tendon sheath is considered a life-threatening emergency
true: stabilize horse and limb before moving further.
flexor tendons: dorsal splint (Kimzey)
what do you see when the SDFT alone is lacerated?**
mild hyperextension
what do you see when the SDFT and DDFT are lacerated?**
moderate hyperextension and elevation of toe off ground
what do you see when SDFT, DDFT and suspensory ligament are lacerated?**
complete loss of fetlock join support
how do you approach tendon lacerations involving synovial structure?
- life threatening! emerg
- synoviocentesis of synovial structure
- synovial arthoscopic lavage and debridement
- abx therapy
- injection? coaptation?
stages of tendon healing
- acute inflammatory phase: 1-2 weeks
- subacute reparative/fibroblastic phase: 2-28d
- remodeling phase: 60days-18 months
acute inflammatory stage
- hemorrhage
- edema
- fibrin accumulation
- local swelling
- increased risk reinjury!
subacute reparative/fibroblastic phase
- 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
maturation/remodeling phase
- fibroblasts make type 1 collagen
- collagen bundles orient along lines of stress
- vascularity and cellularity decreased
treatment for tendon/ligament injuries?
- surgical vs medical
- phase of disease: acute, subacute, chronic
flexor tendon laceration approach **
- debride vs suture tendon closed?
- suture patterns: 3 loop pulley vs interlocking loop
- distal limb cast 6-8 weeks
- 55% return to athletic function
compare suture patterns used to fix flexor tendon lacerations**
- three loop pulley:
- prevents distraction tendon ends - interlocking loop:
- little suture left outside tendon: used for intrathecal tendon repair (within tendon sheath)
- not as strong as 3 loop pulley
what suture approach is stronger for flexor tendon lacerations: 3 loop pulley or interlocking?**
three loop pulley
how long do flexor tendon lacerations need to be in a cast
6-8 weeks
what has a better return to athleticism: flexor or extensor tendon injuries?
extensors: 70-80% return
flexors: 55% return
approach to extensor tendon lacerations
- debride and close
- splint bandage or cast if knuckling
- exercise confinement 4-6 weeks
- complications: granulation tissue, sequestrum formation
physical treatments for tendon/ligament injuries
- cold therapy
- compression/coaptation
- shoeing
- controlled exercise
- shockwave therapy
- US
- low level laser therapy
pharmacologic treatments for tendon/ligament injuries
- systemic: NSAIDs, corticosteroids
- intralesional: hyaluronan, corticosteroids, biologics
what biological therapies can be used with tendon/ligament injuries?
- bone marrow/adipose mesenchymal stromal cells
- autologous conditioned serum
- bone marrow aspirate concentrate
- platelet rich plasma
acute stage care
- exercise confinement
- minimize inflammation
- support tendon/ligament
subacute stage care
- controlled exercise: aligns collagen fibers, walking swimming
- ultrasounds
chronic stage care
- rehab exercises
- tendon splitting?
- counter-irritation “firing” or “blistering” SHOULD BE ABANDONED
