17 Surgery of the Carpus, Metacarpus, Phalanges, and Sesamoids

Palmigrade stance (plantigrade is the back leg)

This occurs when the foot is positioned such that the palmar surface of the metacarpus contacts the ground, common with carpal fractures

Valgus position

This is outward deviation of a foot

Varus position

This is inward deviation of a foot

Palmigrade stance

What is this?

Carpal joint serves MAJOR weight bearing function

Why are carpal fractures disabling?

Radial carpal bone fracture

What is the most commonly diagnosed carpal bone fracture in companion animals?

joint incongruity and development of osteoarthritis --> severe lameness

Without treatment, what may happen with carpal fractures?

Radial carpal bone fractures

Boxers and sporting breeds are most commonly affected by what type of fracture?

Racing greyhound and sled dogs

Accessory carpal bone fractures occur most commonly in what type of animal?

RIGHT leg

Most commonly, accessory carpal bone fractures occur in which leg?

TRUE

TRUE OR FALSE: accessory carpal bone fractures are considered avulsion injuries

Radial carpal bone

Incomplete ossification is suspected to cause fracture of what bone?

MEDICAL

Medical/surgical therapy is typically NOT INDICATED for carpal fractures.

Carpal arthrodesis

What is the best way to treat (chronic) radial carpal bone fractures?

radial carpal bone

This bone articulates primarily with the radius and serves as a major weight bearing area in joint?

Stabilization of radial carpal bone fracture = LAG SCREW

What is this?

Hyperextension injury

What is the most common type of carpus injury?

PANarthrodesis = 3 steps: remove cartilage, autogenous cancellous bone graft, rigid fixation (plate)

How can you treat carpal hyperextension?

PARTIAL arthrodesis

How can you treat carpal hyperextension when radiocarpal is normal?

Conservative splinting

What modality is RARELY SUCCESSFUL for carpal hyperextension?

Bilateral carpal hyperextension injury

What is this?

Partial carpal arthrodesis

What kind of treatment can you do for carpal hyperextension but the radiocarpal joint is NORMAL?

COAPTATION WITH SPLINT FOR 6 WEEKS

What MUST BE DONE and FOR HOW LONG after surgery for carpal hyperextension?

ONLY if they cause a problem (ex. infected, get loose, etc)

When do you remove screws for reconstruction of radiocarpal bone?

Carpal laxity syndrome

What is this?

Sesamoid bones

These are small, round or oblong bones found adjacent to metacarpophalangeal joints

Direct blow/force to paw OR from hyperextension injuries

What more commonly causes metacarpal bone fractures?

Metacarpal bone fracture

This type of fracture commonly occurs in racing greyhounds due to fatigue or normal bone loaded beyond its yield strain

Greyhounds and Rottweilers

Sesamoid fractures are more common in WHAT breeds?

FORELIMB: sesamoid bones 2 and 7 (there are 8 total, count starting on medial side)

WHICH sesamoid bones are more commonly affected by fractures?

Fragmentation of the second (right side of image) and seventh (left side) sesamoid bones

What is happening here?

History of acute lameness that subsided but recurred with exercise. If CHRONIC LAMENESS = remove

What will the history and symptoms be like in dogs with sesamoid fractures?

Acute

Which type of luxation more commonly occurs in working or racing dogs, acute or chronic

chronic

Which type of luxation can be treated with amputation of the 2nd and 5th toe? chronic or acute

2nd and 5th

Which digits can you amputate because they are NON WEIGHT bearing?

Arthrodesis

Besides amputation, what is the more common treatment for luxation of metacarpophalangeal interpalangeal joints?

Metacarpophalangeal joints or interphalangeal joints

Where does luxation typically occur in greyhounds and working dogs?

Orthopedic wire, IM pins, plates/screws

Name the fixation systems applicable for phalangeal fractures/luxations:

TRUE

TRUE OR FALSE: Early surgical repair of metacarpophalangeal joint or interphalangeal joint luxations yield better than closed reduction/splintage because chronic instability leads to DJD.

Digit amputation

What are these landmarks for?

WEIGHT bearing

Digits 3 and 4 are weight bearing/nonweight bearing

FALSE: The MORE DISTAL = better prognosis (but if it's cancer, you're going to need to go more proximal for a better prognosis)

TRUE OR FALSE: the more proximal the digit amputation, the better the prognosis

1. make elliptical skin incision

2. preserve pad (use sharp dissection, no scissors)

3. remove sesamoids

Name the steps for performing digit amputations:

Avoid LOCAL RECURRENCE = amputate at spot 2

You see a mass. WHERE should you amputate for the best prognosis but preserving the limb as much as possible?

Comminuted fracture of palmar sesamoid on left, image B shows resection of bone fragments

What is this?

Digit arthrodesis

In this procedure, you expose the joint, open the joint capsule, remove articular cartilage, contour surfaces, and temporarily hold bones in position, contour small plate, attach plate, and use K-wire and tension band

Digit arthrodesis with plate and lag screw

What is A?

Digit arthrodesis with K wires and tension band

What is B?

xx

FYI