Large Animal Tendon/Ligament Injuries

Question 1

what are the 5 commonly injured tendons/ligaments in the horse?

Answer 1

1. superficial digital flexor tendon
2. deep digital flexor tendon
3. inferior check ligament
4. suspensory ligament
5. distal sesamoidean ligament

Question 2

what are 4 common clinical signs of soft tissue injuries?

Answer 2

1. swelling at site of injury
2. heat at site of injury
3. pain on palpation at site of injury
4. lameness (often more apparent on soft versus hard surface)

Question 3

describe superficial digital flexor tendinopathy

Answer 3

1. SDFT originates from the radius and inserts on the middle scutum (pastern region) and acts as a spring to propel the limb
2. common locations injured: metacarpus and proximal pastern
3. clinical signs:
   -variable acute lameness
   -swelling, pain on palpation, heat
   -tendon sheath effusion if injured in digital flexor tendon sheath
4. diagnosis: ultrasound
5. older horse: can have degeneration of SDFT; typically proximal metacarpus, carpal canal, check for pars pituitary intermedia dysfunction (PPID)
6. if occurs due to laceration or severe injury, clinical signs will be severe, acute swelling and lameness with a dropped fetlock

Question 4

describe deep digital flexor tendinopathy

Answer 4

1. 3 heads, originate from radius and insert on P3
2. commonly injured at
   -distal metacarpus/metatarsus
   -pastern region
   -foot (level of navicular bursa)
   -insertion
3. clinical signs:
   -variable acute lameness
   -swelling, pain on palpation, heat (dependent on location)
   -tendon sheath effusion if injured in digital flexor tendon sheath
   -if injured at level of navicular bursa, may not have obvious clinical signs but might be sensitive to hoof testers across heel
4. diagnosis: ultrasound and MRI

Question 5

who are the soft tissue neighbors of the navicular bone?

Answer 5

1. DDFT
2. navicular bursa

need to consider both

Question 6

describe deep digital tendon rupture

Answer 6

1. can occur due to laceration or severe breakdown injury
2. clinical signs: acute, severe lameness
   -toe will be off the ground!

Question 7

describe inferior check ligament desmopathy

Answer 7

1. inferior check ligament (distal check of accessory ligament) originates on the palmar aspect of MC III and its insertion blends in with the DDFT; located in the proximal 1/3 of metacarpus
2. in hindlimb, check ligament is small and often difficult to visualize
3. commonly injured the forelimb
4. clinical signs:
   -lameness usually mild (grade 1-2/5)
   -swelling in proximal 1/3 of metacarpus
5. diagnosis: ultrasound, image from lateral approach!

Question 8

describe suspensory ligament desmopathy

Answer 8

1. suspensory ligament originates on proximal metacarpus/tarsus and inserts on proximal sesamoid bones
2. commonly injured at: proximal aspect, branches, or midbody (races in the hindlimb)

Question 9

describe proximal suspensory desmopathy

Answer 9

1. common in sporthorses, forelimb and hind limb
2. clinical signs:
   -highly variable lameness
   -might have pain on palpation
   -forelimb: lameness often worse with leg on outside of circle
   -hindlimb:
   –lameness (inside or outside limb when circling)
   –trouble picking up correct lead at canter
   –lack of impulsion
   –reluctance to work
3. ultrasound:
   -proximal suspensory contains ligament and fat/muscle bundles
   -pain can come from: ligament, bone (enthesopathy (extra bone formation where soft tissues attach) or sclerosis (more dense bone)), or nerves
   -non-weight bearing ultrasound most helpful, but may often need an MRI to pick up more subtle changes

Question 10

describe suspensory branch desmopathy

Answer 10

1. clinical signs:
   -variable lameness
   -swelling at fetlock region: may have acute effusion in the palmar/plantar pouch of the fetlock joint and digital flexor tendon sheath
   -variable pain on palpation
2. ultrasound:
   -no fat/muscle bundles present
   -make sure to US the branches IF
   –sesamoiditis seen on fetlock rads or
   –proximal sesamoid bone fragments seen on fetlock rads
   -ultrasound entire suspensory ligament if splint bone fracture or severe exostosis present

Question 11

describe suspensory avulsion fractures

Answer 11

can occur at origin or insertion if pull of ligament is stronger than the bone

Question 12

describe the distal sesamoidean ligaments; be able to name them!

Answer 12

2 obliques and 1 straight

Question 13

describe desmopathy of the distal sesamoidean ligaments

Answer 13

1. most commonly injured are:
   -straight sesamoidean ligaments anywhere in the ligament
   -oblique sesamoidean ligaments: most commonly at the origin
2. clinical signs:
   -variable lameness (usually 3/5 or less)
   -may have swelling in pastern region
   -may have pain on palpation
3. diagnosis: ultrasound and MRI

Question 14

describe degenerative suspensory ligament desmitis

Answer 14

1. DSLD: progressive degeneration of the entire suspensory apparatus due to proteoglycan accumulation
2. affects all soft tissues in the body but suspensory apparatus most clinically apparent
3. affects hindlimbs prior to forelimbs, will see a dropped fetlock!
4. diagnosis: ultrasound can be supportive, biopsy of nuchal ligament needed for definitive
5. treatment: supportive care; disease is progressive regardless of treatment
   -NSAIDs
   -therapeutic shoeing (heel extensions)
   -reduction in exercise

Question 15

how long does it take tendons to heal? ligaments?

Answer 15

tendon: 6 letters = 6-12 months

ligament: 8 letter = 8-12 months

Question 16

describe conservative treatment options for tendon and ligament healing

Answer 16

1. controlled exercise: hand walking
2. physiotherapy exercises: eccentric loading beneficial
3. icing
4. heat once chronic if scar tissue, peritendinous (ligamentous) thickening present
5. NSAIDs: systemic/topical
6. orthobiologics: expensive
7. additional therapies: ESWT, LASER, therapeutic ultrasound: goal is to decrease patient pain and stimulate healing, but will not decrease time needed to heal
8. rehab plan: gradual increase in exercise, goal of returning to full work by end of recovery period, but risk of reinjury always possible; weakest at junction of normal and abnormal tissue