Auer Ch 91 Phalanges, Fetlock

Front 1

How is P2 loaded?

Back 1

Axial and torsional planes

Front 2

Who is predisposed to P2 fractures?

Back 2

Horses turning on hindlimbs such as western performance horses or jumpers

Front 3

Categories of P2 fractures:

Back 3

dorsal/ palmar-plantar IA OC chip, palmar-plantar eminence, axial, comminuted

Front 4

Where do P2 OC fractures occur?

Back 4

Most often palmar-plantar, immediately medial or lateral to midline

Front 5

Treatment of P2 OC fractures:

Back 5

arthroscopic removal if determined to cause lameness

Front 6

Approaches to surgical removal of P2 OC fractures:

Back 6

dorsal or palmar-plantar arthroscopy preferred, open approach through DFTS for palmar-plantar or arthrotomy dorsally

Front 7

Mechanism of palmar-plantar P2 eminence fractures:

Back 7

hyperextension of pastern joint with tension on palmar-plantar attachments of SDFT, middle scutum, and distal sesamoidean ligaments

Front 8

How are uniaxial P2 eminence fractures treated?

Back 8

Lag screw fixation or pastern arthrodesis

Front 9

How are biaxial P2 eminence fractures treated?

Back 9

Pastern arthrodesis (with interfragmentary compression through plate or in addition to plate)

Front 10

Treatment of axial P2 fracture:

Back 10

lag screw fixation + casting for 4 weeks

Front 11

Treatment of comminuted P2 fracture:

Back 11

lag screw fixation for minimally comminuted fractures, single LCP or DCP with interfragmentary screws, 2 LCP or DCP for pastern arthrodesis, lag screw fixation + TPC

Front 12

Which P2 fracture fixation option optimizes chances for adequate reconstruction of distal P2 articular surface?

Back 12

Plate fixation with independent lag screw fixation of fracture

Front 13

When is TPC used for P2 fractures?

Back 13

Fractures than can not be reduced and stabilized with implants and euthanasia is not an option

Front 14

What decreases the prognosis for P2 fracture fixation repair?

Back 14

Fragments entering DIP joint, compromise to vasculature and soft tissue structures, concurrent fracture of NB

Front 15

Treatment of PIP OA:

Back 15

IA corticosteroid injection, alcohol facilitated ankylosis, pastern arthrodesis

Front 16

Arthrodesis options for PIP OA:

Back 16

2-3 5.5 transarticular screws, LCP or DCP with or without adjacent transarticular screws, minimally invasive placement of 1 or 2 LCP with or without transarticular screws, laser ablastion with 2 5.5 transarticular screws

Front 17

What types of OC lesions affect PIP joint?

Back 17

SCL more often than OCD, usually distal articular surface of P1 (more than proximal articular surface of P2)

Front 18

Treatment of PIP SCL:

Back 18

solitary SCL treated with transosseous drilling, curettage of SCL, and grafting with tricalcium phosphate granules or hydrogel with parathormone; multiple SCL treated with pastern arthrodesis

Front 19

Treatment of PIP luxation or subluxation:

Back 19

for dorsal subluxation due to upright conformation, NSAIDs and controlled exercise; for dorsal subluxation due to tension on DDFT, release of medial head of DDFT; for others, pastern arthrodesis

Front 20

What causes dorsal PIP subluxation?

Back 20

Damage to SL and SL extensor branches or occasionally contracture of distal sesamoidean ligaments or excessive tension on DDFT

Front 21

What causes palmar-plantar PIP subluxation?

Back 21

Failure of distal sesamoidean ligament, middle scutum, SDFT insertions on P2 due to hyperextension

Front 22

Categories of P1 fractures:

Back 22

proximal IA OC fractures (dorsal and palmar-plantar), fractures of the shaft or diaphysis

Front 23

Cause of dorsal proximal IA P1 OC fractures:

Back 23

hyperextension of the MC/MTP joint with impact of proximal P1 on the dorsal aspect of distal MC/MT3

Front 24

Most common location of dorsal proximal IA P1 OC fractures:

Back 24

dorsomedial eminence of P1

Front 25

Treatment of dorsoproximal IA P1 OC fracture:

Back 25

small fragments can be left if not causing lameness, larger fragments are removed with dorsal fetlock arthroscopic approach

Front 26

Post-op care dorsoproximal IA P1 OC fractures:

Back 26

rest 6-12 weeks depending on damage to MC3 cartilage

Front 27

Types of palmar-plantar proximal IA P1 OC fractures:

Back 27

1: avulsion from axial, proximal, plantar-palmar rim of P1, mostly articular, extensive attachment of short sesamodian ligament; 2: large, abaxial, partially articular fractures extending 2-3 cm distally with minimal articular cartilage

Front 28

Radiographic projection for palmar-plantar type 1 P1 OC fracture:

Back 28

proximo-20-dorso-15-lateral to distal palmaromedial or proximo-20-dorso-15-medial to distal palmarolateral

Front 29

Treatment of type 1 P1 OC fractures:

Back 29

arthroscopic removal

Front 30

Treatment of type 2 P1 OC fractures:

Back 30

removal only if causing lameness, even if radiographic fusion is not evident

Front 31

Post-op care for palmar-plantar type 1 P1 OC fractures:

Back 31

6-12 weeks rest depending on degree of short sesamoidean ligament injury

Front 32

Characteristics of dorsal frontal P1 fractures:

Back 32

short, extending 2-5 cm distal in the dorsolateral cortex, complete, minimally displaced

Front 33

Treatment of dorsal frontal P1 fractures:

Back 33

complete: lag screw fixation using 1 or 2 3.5 cortex screws with arthroscopic reduction of articular surface; incomplete: stall rest or lag screw fixation

Front 34

Most common characteristics of P1 diaphyseal fractures:

Back 34

sagittal, distal from articular surface from mid-sagittal groove

Front 35

Mechanism of P1 diaphyseal fractures:

Back 35

torsion with axial weight bearing applied to sagittal groove of P1 from sagittal ridge of MC/MT3

Front 36

Treatment of short P1 sagittal fractures:

Back 36

if incomplete, conservative therapy or lag screw fixation

Front 37

Prerequisite of P1 fracture repair:

Back 37

intact strut of bone spanning from MC/MTP joint to PIP joint

Front 38

Treatment of complete, non-displaced P1 diaphyseal fractures:

Back 38

lag screw fixation with a proximal 5.5 cortex screw placed within 5mm of the distal point of the sagittal groove, and the rest of the fracture fixed with 4.5 cortex screws, post-operative cast (hind limb) or bandage/ splint (fore limb)

Front 39

Treatment of mild to moderate displaced P1 diaphyseal fractures:

Back 39

open, dorsal with I or S shaped incision for articular alignment and interfragmentary screw placement

Front 40

Benefits of I shaped dorsal approach to P1 diaphyseal fractures:

Back 40

exposes entire dorsal surface, preservation of collateral ligaments

Front 41

Disadvantages of S shaped dorsal approach to P1 diaphyseal fractures:

Back 41

transection of collateral ligament of fetlock joint

Front 42

Treatment of severely comminuted diaphyseal P1 fractures:

Back 42

salvage TPC or external skeletal fixation device

Front 43

Disadvantages of cast only fixation of diaphyseal P1 fractures:

Back 43

cast does not provide resistance to axial collapse of the fracture

Front 44

What is the cause of palmar MC fragmentation?

Back 44

Accumulation of stress and sclerosis of the palmar MC condyles because of hyperextension during racing

Front 45

Radiographic projection for palmar MC fragmentation?

Back 45

125-dorsopalmar

Front 46

Radiographic appearance of palmar MC fragmentation:

Back 46

differently shaped defects with intense sclerosis of the palmar condyle, secondary OA

Front 47

Lesion associated with palmar MC fragmentation:

Back 47

acellular necrotic bone over the entire distal palmar MC condyle, with a sclerotic zone deep to the necrotic bone

Front 48

Treatment of palmar MC fragmentation:

Back 48

none (conservative) because develop in region not accessible arthroscopically

Front 49

Types of PSB fractures:

Back 49

apical, mid-body, basal, abaxial, sagittal, comminuted

Front 50

What predicts prognosis with apical PSB fractures?

Back 50

Extent of loss of SL insertion and preexisting SL desmitis

Front 51

What percent of the PSB is involved with articular apical fractures?

Back 51

PSB fractures involving ¼ - 1/3 of the bone are always articular

Front 52

Treatment for apical PSB fractures:

Back 52

for fragments up to 1/3of the PSB, palmar arthroscopic removal, large fragments need internal fixation

Front 53

Treatment of mid-body PSB fractures:

Back 53

internal fixation with cerclage wire (STB) or lag screws (TB)

Front 54

How is lag screw fixation of mid-body PSB fractures performed?

Back 54

Oblique fracture declining from medial to lateral has screw placed proximolaterally from the apex embedded in the insertion of the SL branch; oblique fractures declining from lateral to medial has screw placed from base in a fossa between the oblique and straight distal sesamoidean ligament or from a contralateral approach for proximal to distal screw insertion

Front 55

What affects the prognosis for basal PSB fractures?

Back 55

Involvement of distal sesamoidean ligament and thin fragment profile

Front 56

Treatment of basal PSB fractures:

Back 56

if less than 25% of base, remove fragment, if more than 25% consider internal fixation

Front 57

Radiographic projection for abaxial PSB fracture:

Back 57

60 degree skyline of abaxial PSB surface to determine if IA or not

Front 58

Treatment of abaxial PSB fracture:

Back 58

if IA, remove by arthroscopy, if not IA, conservative management

Front 59

Where and when do sagittal PSB fractures occur?

Back 59

Axial margin of PSB in conjuction with other MCP joint injuries such as condyle fractures

Front 60

Treatment of sagittal PSB fractures:

Back 60

if no other injuries, lag screw fixation from lateral to medial with 3.5mm cortex screws

Front 61

What is chronic proliferative or villnodular synovitis?

Back 61

Development of soft tissue mass in dorsal MCP joint secondary to chronic fibrosing synovitis or advancing OA

Front 62

Radiographic features of chronic proliferative synovitis:

Back 62

cortical lysis on dorsal distal MC3 with enlarged ST mass

Front 63

Best diagnostic imaging for diagnosis of chronic proliferative synovitis:

Back 63

ultrasound

Front 64

What is critical for surgical decision regarding chronic proliferative synovitis?

Back 64

Extent of OA

Front 65

Treatment of palmar-plantar MC/MT3 OCD:

Back 65

none, unless accessible via arthroscopy, which is rare

Front 66

Treatment of dorsal sagittal ridge or parasagittal MC/MT3 OCD:

Back 66

arthroscopic removal

Front 67

Treatment of distal MC/MT3 SCL:

Back 67

if accessible by arthroscopy and dorsal to the transverse ridge of MC/MT3, debridement through arthroscopic approach, if not accessible arthroscopically, does not communicate with joint, or located palmar-plantarly, transosseous approach with debridement and graft therapy

Front 68

Cause of fetlock luxation:

Back 68

rupture of either medial or lateral collateral ligament, usually from entrapment of the distal limb in a hole

Front 69

Treatment of closed fetlock luxation:

Back 69

cast immobilization for 6 weeks

Front 70

Treatment of open fetlock luxation:

Back 70

joint and wound lavage and debridement, support in splint until infection cleared, then support in cast or arthrodesis

Front 71

Disadvantages of open approach to DFTS:

Back 71

delay in initiation of exercise post-operatively which increases risk of adhesion formation, increase wound dehiscence if exercise is initiated too early

Front 72

Options for annular ligament desmotomy:

Back 72

open approach with incision over entire length of ligament, closed approach with paramedian incision over entire length of ligament, 1 cm proximal incision with blind transection with curved bistoury, 2 cm proximal incision, tenoscopy transection with 90 degree angled blade, bistoury, or RF probe

Front 73

Post-op care for DFTS tenoscopy:

Back 73

bandaging for 3-4 weeks, walking after 5 days, intrathecal HA

Front 74

Most common type of ruminant MC/MT fracture:

Back 74

distal metaphysis from forced fetal extraction, SH type 1 or 2 in non-neonates, mid-diaphyseal in adults

Front 75

Fixation of neonatal ruminant distal metaphyseal MC/MT fractures:

Back 75

external coaptation or external skeletal fixation

Front 76

Internal fixation of ruminant MC/MT fractures:

Back 76

external fixation in smaller animals, internal fixation with double plating (1 dorsal) for larger animals