La Surgery -- Fetlock Lameness

Front 1

Fetlock is comprised of which structures (4)?

Back 1

-- metacarpal/metatarsal III

-- phalanx 1

-- two sesamoid bones

-- suspensory apparatus

Front 2

Suspensory apparatus includes which structures?

Back 2

-- suspensory ligement

-- sesamoid bones

-- distal sesamoidean ligaments

Front 3

Why is the fetlock susceptible to injury?

Back 3

-- angular design

-- large range of motion (270 degrees)

-- small cross section weight bearing surfaces

-- lack of soft tissue covering

Front 4

Implications of angular design of fetlock for susceptibility to injury?

Back 4

-- multiple force vectors acting on the joint during normal movement

>> injury to the fetlock is more complicated to treat

Front 5

Fetlock examination?

Back 5

-- fluid distention?

-- fetlock flexion test (degree of motion, pain)

-- metacarpophalangeal joint block

-- radiographs

Front 6

Ways to do the metacarpophalangeal joint block?

Back 6

-- palmar/plantar pouch

-- dorsal surface under common (long) digital extensor tendon

-- through lateral collateral sesamoidean ligament

Front 7

Radiographic views of carpus?

Back 7

-- lateral

-- dorsopalmar (plantar)

-- medial and lateral obliques

Front 8

Synovial effusion in any horse <4y should make you suspicious for?

Back 8

osteochondrosis

>> young animals that have not had much structured exercise or extensive training yet

Front 9

Sites of OCD in the fetlock?

Back 9

-- midsaggital ridge (cranial aspect MC III)

-- lytic lesions on distal metacarpus

-- OCD fragments: cranial aspect P1 or MC/MT III

>> may be confused for chip fracture

Front 10

Causes of traumatic arthritis?

Back 10

-- conformation

-- stress

-- strain

-- concussion

-- overuse

Front 11

Signs of traumatic fetlock arthritis?

Back 11

-- inc. synovial effusion

-- poor viscosity

-- pain (responds to rest)

Front 12

What are osselets?

Back 12

-- traumatic synovitis and capsulitis

-- chronic thickening and inflammation of joint capsule

>> "green osselets" if no osseous radiographic lesions

Front 13

Causes of osselets?

Back 13

-- trauma

-- hyperextension of metacarpophalangeal jt

-- overweight horse/rider

-- confomrational defects

-- classic: young racehorse

Front 14

Diagnosis of osselets?

Back 14

-- lameness& swelling of fetlock

>> inc. synovial fluid, edema, hyperemia of jt capsule result in thickening

-- erosion of proximo-dorsal aspect of P1

-- entesophytes: ossification of jt capsule attach

-- osteophytes: prox/distal articular margins of sesamoids

-- supracondylar lysis of caudal border of MIII

--flattening of caudal condylar borders MIII

Front 15

Treatment of osselets?

Back 15

-- enforced rest early in the course of the disease

(90-120 days)

-- intraarticular steroids, hyaluronate or PSGAG, platelet-rich plasma, shock-wave therapy

Front 16

Contraindicated for treatment of osselets?

Back 16

-- use of steroids and continued work

>> DJD may progress at accelerated rate

Front 17

Advanced degenerative joint disease?

Back 17

-- effusion

-- swollen joint

-- lameness + flexion

Front 18

Chronic proliferative synovitis?

Back 18

-- development of intracapsular mass over a period of several months

-- redundant fold of synovial tissue, projecting from the dorsal proximal aspect of joint capsule

>> becomes traumatized during dorsiflexion

Front 19

Causes of chronic proliferative synovitis?

Back 19

-- excessive dorsiflexion of the fetlock

-- trauma to synovial tissue

-- fibrosis of the synovial tissue

Front 20

Diagnosis of chronic proliferative synovitis?

Back 20

-- lameness when worked, sound when rested

-- enlarging mass causes ST swelling under common digital extensor tendon >> may be palpated (joint feels very thick)

-- pressure necrosis cranial metacarpal bone

>> concavity noticible on rads

-- US may be helpful for dx of lesions

Front 21

Conservative treatment of chronic proliferative synovitis?

Back 21

-- intraarticular injection of steroids

-- prolonged rest (90 days)

Front 22

Surgical treatment of chronic proliferative synovitis?

Back 22

-- surgical removal of chronic proliferative synovitis via fetlock arthroscopy

>> look for signs of irreversible OA

>> is horse a good surgical candidate?

Front 23

Where do chip fx of P1 occur?

Back 23

-- medial to common digital extensor tendon

>> medial aspect of jt surface is larger

>> more weight is borne medially

>> contacts MIII bone first in dorsiflexion

Front 24

Causes of chip fractures of P1?

Back 24

-- trauma, dorsiflexion >> usually in athletic horse

-- common fracture in thoroughbreds

Front 25

Diagnosis of dorsal margin chip fractures of P1?

Back 25

-- ST swelling, effusion, and pain on flexion

-- signs worst at 12-24h after occurrence

-- horse may be sound but get sore when trained

-- radiographs!

Front 26

Are horses with dorsal margin chip fractures of P1 always lame?

Back 26

-- NO

Front 27

Dorsal margin chip fx of P1 are more likely to occur in race horses. T/F?

Back 27

-- true

Front 28

Which type of dorsal proximal margin chip fractures are more likely to cause problems?

Back 28

-- small fx located deep in articular surface

>> cause most damage/lameness

Front 29

Treatment of dorsal proximal margin chip fx of P1?

Back 29

-- ideal arthroscopic candidates

>> sharp dissection nod no curettage of fx bed

-- arthroscopic removal of fx fragment

-- 2-3 mo rest after surgery

Front 30

Cause of palmar fragments of P1?

Back 30

-- etiology is OCD or trauma

Front 31

Sagittal and spiral fractures of P1 are most common in?

Back 31

-- Standardbreds

Front 32

Highest incidence of sagittal and spiral fx occurs in which limb?

Back 32

-- left thoracic limb

Front 33

Cause of sagittal and spiral fx of P1?

Back 33

-- fatigue fx of continued stress

-- fx occur in stages, begin as a fissure

Front 34

Diagnosis of sagittal and spiral fx of P1?

Back 34

-- depend son degree of lameness, pain on palpation, swelling

-- pain on fetlock flexion is characteristic

-- radiographs: dorsopalmar and lateral

Front 35

Treatment of sagittal and spiral fractures?

Back 35

-- 3-4 mo stall rest (short, incomplete sagittal fx)

-- lag screw fixation (longer or displaced fx)

Front 36

Prognosis for sagittal and spiral P1 fx?

Back 36

-- prognosis is good if fx is repaired early and well-aligned

Front 37

What is sesamoiditis?

Back 37

-- condition of proximal sesamoid bones causing chronic lameness

>> flexor and abaxial surfaces involved

-- not a true "itis", too much pull on sesamoids

Front 38

Causes of sesamoiditis?

Back 38

-- conformation

-- stress on the suspensory apparatus due to repeated trauma/strenuous exercise

-- abnormal weight bearing

Front 39

Diagnosis of sesamoiditis?

Back 39

-- heat over sesamoids

-- pain to palpation and fetlock flexion

-- swelling may not be evident

-- lameness increases on hard surfaces

-- radiographs

-- nerve block: high palmar

Front 40

Radiographs for sesamoiditis will show?

Back 40

-- inc. intraosseous canals

-- calcification at fibro-osseous interface of suspensory attachments

Front 41

Treatment of sesamoiditis?

Back 41

-- rest for 90 days (critical!)

> hot walker or swimming

-- heavy support wraps

-- cast (2-3 wks)

-- slow resumption of training is indicated

-- bisphosphonates (not with NSAID!)

Front 42

Bisphosphonates do what?

Back 42

decrease osteoclast activity (maybe)

Front 43

Sesamoid fractures are most common in which breeds?

Back 43

-- thoroughbreds, standardbreds

Front 44

Types of sesamoid fx? Which has the best prognosis?

Back 44

-- apical (best prognosis)

-- mid-body

-- basilar

Front 45

Apical fractures occur? Most often which sesamoid?

Back 45

-- proximal 1/3 of bone

-- right lateral sesamoid

Front 46

Cause of sesamoid fx?

Back 46

-- excessive loading of one br. of suspensory ligament

>> bone failure

>> usually outside leg near end of a race

Front 47

Diagnosis of sesamoid fx?

Back 47

-- pain, heat, swelling over affected bone

-- characteristic pyramid-shaped swelling

-- oblique radiographs most helpful

Front 48

Prior to surgery for sesamoid fx, it is important to check what?

Back 48

-- condition of suspensory ligament

Front 49

Treatment of sesamoid fx?

Back 49

-- surgical removal via arthroscopy (or palmar/plantar fetlock arthrotomy)

-- at least 3 mo post-operative rest

Front 50

If > ___ % suspensory attachment is involved, prognosis is decreased.

Back 50

-- >25% suspensory attachment is involved

Front 51

Basilar fx occur where?

Back 51

distal 1/3 of sesamoid

>> medial sesamoid is most often involved

>> almost always articular fx

>> "T" fx often occur

Front 52

Why do basilar sesamoidean fx carry a poor prognosis?

Back 52

distal sesamoidian ligament involvement

Front 53

Treatment of mid-body (transverse) sesamoidean fx?

Back 53

seamoid is fx mid-way

>> lag screw fixation

>> neither fragment may be safely removed w/o disruption of suspensory apparatus

Front 54

What are condylar fx of MIII?

Back 54

start on articular surface and extend proximally on the cannon bone

Front 55

Condylar fx of MIII are complete if?

Back 55

they exit the lateral cortex

Front 56

Condylar fx repair?

Back 56

internal fixation (lag screws)

>> non-displaced fx: percutaneous placement

>> displaced fx: sx exposure/reduction prior to screw placement

-- 3-4 mo rest