Radiology Packet 45

Carpus and Metacarpus

13-year old Appaloosa“Joker”

Hx: Chronic lameness of front limbs. The films were taken to rule out a problem in the right carpus.

13-year old Appaloosa“Joker”

• RF– The soft tissues surrounding the carpal joint are thickened. This is especially

prominent on the dorsal surface of the joint.– The fat pad that is normally present at the dorsal aspect of the middle carpal joint

is not present.– In the DLPMO view the distal margin of the radial carpal bone is flared and more

lucent than the adjacent bone.

• RD– Mild degenerative joint disease of the middle carpal joint– Capsular distension of the middle carpal joint– Minor osteophyte formation on the dorsomedial margin of the middle carpal joint

6-year old Standardbred“Policy maker”

• No history provided

6-year old Standardbred“Policy maker”

• RF– The soft tissues surrounding the carpal joint are thickened.– The fat pad that is normally present at the dorsal aspect of the middle carpal joint is not

present.– Osteophyte formation is present on the dorsal, dorsomedial and dorsolateral margins of the

middle carpal and carpometacarpal joints.– Significant irregular periosteal new bone is present on the dorsal, dorsomedial and

dorsolateral surfaces of the radial carpal bone, intermediate carpal bone and 3 rd carpal bone.– There is periosteal response on the dorsomedial surface of the 3 rd metacarpal bone.– The medial aspect of the middle carpal joint is narrowed suggesting a loss of cartilage.

• RD– Degenerative joint disease of the middle carpal and carpometacarpal joints

• R/O– Joint sepsis secondary to joint injection.– DJD due to multiple corticosteroid injections.

2-year old Standardbred“Pandora’s Box”

• Hx: 7 week history of right forelimb lameness.

2-year old Standardbred “Pandora’s Box”

• RF– Large corner fracture rising from the medial aspect of the third carpal

bone is identified. – The fracture appears chronic in nature judged by smooth margins and a

wide fracture gap.– There is sclerosis of the surrounding radial fossa.– The fracture is not felt to extend to the distal aspect of the joint surface.– Effusion of the middle carpal joint is present.

• RD– Large, chronic corner fracture off the radial fossa of the right third carpal

bone

4-year old Standardbred“Master Cam”

• Hx: 3-4 month history of lameness of the right forelimb. The lameness has been localized to the carpus.

4-year old Standardbred“Master Cam”

• RF– The soft tissues surrounding the carpal joint are markedly thickened.– The fat pad that is normally present at the dorsal aspect of the middle carpal joint

is not present.– Multiple small osseous fragments are visible in the dorsal aspect of the joint.– In the DLPMO view the dorsomediodistal margin of the radial carpal bone is

much more lucent than the adjacent bone.– Careful evaluation shows a linear lucency separating the corner of the bone from

the rest of the bone. – In the flexed lateral view a small distinct bone fragment is visible at the

dorsoproximal margin of the distal carpal row. This fragment most likely arises from the 3rd carpal bone.

– In the dorsoproximo-dorsodistal oblique (skyline) projection of the distal row of carpal bones a bone fragment is seen at the dosomedial margin of the 3rd carpal bone. There is increased opacity of the radial facet of the 3rd carpal bone.

– The surface of the 3rd carpal bone is irregular and more lucent than normal medial to the bone fragment.

4-year old Standardbred“Master Cam”

• RD– Corner fracture of the distal radial carpal bones– Marginal fracture of the proximal third carpal bone– Multiple small fracture fragments present within the joint capsule– Sclerosis of the radial facet of the third carpal bone with evidence of subchondral

lysis of bone.– Severe capsular distension of the middle carpal joint.

3-year old Standardbred“Selkirk’s Ace”

• Hx: The horse is grade 3 of 4 lame in the left forelimb. Left forelimb lameness has been milder and intermittent but I becoming worse.

3-year old Standardbred“Selkirk’s Ace”

• RF– There is a large area of proliferative bone on the mid-portion of the medial splint

bone (MC2). The surface of the periosteal response is smooth.– The soft tissue of the palmaromedial and palmarolateral aspect of the limb are

markedly thickened.– There is an incidental finding of a 1st carpal bone.

• RD– Exostosis of the medial splint bone, believed to be chronic– Soft tissue thickening of the flexor region

• R/O– Injury to superficial and/or deep digital flexor tendons (flexor tendonitis, “bowed”

tendon)

• Next– Ultrasound

6-year old Standardbred“All Lies”

• Hx: Two week history of training injury to the left forelimb. Persistent lameness and soft tissue swelling.

6-year old Standardbred“All Lies”

• RF– Periosteal response is visible on the margins of the distal 2nd metacarpal bone.– A fracture is present at the distal extent of the bone.– Mild thickening of the palmaromedial soft tissues is noted.– Periosteal response is visible on the margins of the distal ½ of the 4 th metacarpal

bone.– Two fractures are present in this bone, one distally and one at approximately the

mid-portion of the bone.– Moderate thickening of the palmarolateral soft tissues is noted.

• RD– Fractures of the medial (MC 2) and lateral (MC 4) splint bones of the left forelimb

• R/O– Inflammation of the branches of the suspensory ligament causing splint fractures.

• Next– Ultrasound

2-year old Standardbred“Gordon Shumway”

• Hx: The horse developed severe lameness of the left forelimb immediately after racing.

2-year old Standardbred“Gordon Shumway”

• RF– The soft tissues surrounding the carpal joint are thickened.– The fat pad that is normally present at the dorsal aspect of the middle carpal joint is not present.– Several small osseous fragments are visible in the caudal aspect of the joint at the level of the

distal row of carpal bones.– In the lateral view there is a displaced slab fracture in the distal row of carpal bones. – The dorsoproximo-dorsodistal oblique of the distal carpal row shows that the fracture is in the

third carpal bone. In this view the fracture line is visible at the medial margin of the bone.– There is increased opacity of the radial facet of the third carpal bone.– There is an incidental finding of subtle periosteal proliferation on the caudal aspect of the distal

radius at the area of attachment of the superior check ligament and may be evidence of increased stress on the superficial digital flexor tendon.

• RD– Slab fracture of the third carpal bone– Radial facet sclerosis of the third carpal bone

• R/O– Non-adaptive exercise induced bone remodeling leading to bone fracture.

4-year old Appaloosa“Lucy”

• Hx: Swelling on the medial aspect of her proximal left metacarpus (cannon bone).

4-year old Appaloosa“Lucy”

• RF– Proliferative bony response is present involving the second metacarpal bone at

the junction between the proximal and middle 1/3 of this bone.

• RD– Trauma to the medial splint bone (MC 2)

• Next– Surgical removal

3-year old Standardbred• Hx: Presented because of acute lameness and swelling of the right

carpus.

3-year old Standardbred• RF

– Soft tissue swelling surrounds the carpus, centered over the middle carpal joint.

– A large rectangular bony fragment is present arising from the distal medial corner of the radial carpal bone.

– Several small fragments of bone are noted in the caudal aspect of the middle carpal bone.

• RD– Corner fracture of the right radial carpal bone