Small Animal Forelimb RVT: Chapter 20

Objectives: Small Animal Forelimb ID common concerns associated with radiographing the small animal forelimb Safely and appropriately position a patient for various common forelimb positions. Know where to measure & center the beam Include appropriate margins Position properly Use non-manual restraint where possible Understand alternative views Distinguish & identify normal forelimb anatomy

Anatomy Review: Forelimb

Terminology Review Dorsal Recumbency Sternal Recumbency Used for: distal forelimb Dorsal Recumbency Used for: proximal forelimb (scapula, shoulder, and humerus)

Radiographic Concerns: Forelimb Field of view: Long bones – include proximal AND distal joints Joints – Include _______ of the bones proximal & distal Most views done via tabletop Collimate tightly Can split film: Point toes the same direction Collimate & shield other side R Mediolateral carpus

Radiographic Concerns: Forelimb Non-manual restraint (where possible) Place label at: Lateral view - dorsal or cranial aspect Other views – lateral aspect Keep bone ______________ to the cassette Increase exposure factors if splints/casts remain in place R Mediolateral Tarsus

The Forelimb: Radiographic Anatomy Shoulder Joint – Mediolateral & CdCr Scapula – Mediolateral & CdCr Humerus – Mediolateral, CdCr or CrCd Elbow – Mediolateral, CrCd Radius/Ulna – Mediolateral, CrCd Foot – Mediolateral, DPa

The Shoulder

Shoulder Joint (Mediolateral View) Positioning: Area of interest __________ to cassette This means affected limb ____________. Extend affected leg cranially & ventrally Contralateral leg pulled out of way Arch head & neck dorsally Hind limbs in natural position Margins: Proximal 1/3 of _________ & 1/3 of scapula

Shoulder Joint (Mediolateral View) Tips: Don’t over-rotate thorax! Leads to an ____________ view Make sure elbow is in lateral- this should ensure shoulder in correct orientation Set-up: Central ray at area of interest Palpate shoulder joint by finding humeral head Do not include both shoulders in measurement Use settings for pelvis/thorax and change as needed

Shoulder Joint (Mediolateral View)

Scapula (Mediolateral View)

Shoulder Joint (Caudocranial View)

Shoulder & Scapula (Caudocranial View) Positioning: Dorsal, with head pulled away from affected limb Extend both forelimbs cranially with humerus parallel to cassette Body & ribs should fall away from affected scapula Can rotate sternum away to avoid superimposition Sedation is sometimes necessary for full extension. Shoulder margins: Proximal third of humerus & distal third of scapula Scapula margins: Entire scapula and shoulder joint Tip: caudal aspect of scapula is at about 8th rib

CdCr Scapula

Humerus (Mediolateral View) *Positioning is identical to shoulder and scapula

Humerus (Mediolateral View) Lateral recumbency with affected leg towards image receptor Affected leg is extended forward Opposite leg drawn back Head and neck extended dorsally Center beam at mid humerus Margins: proximal to ___________ joint & distal to ___________ joint

Humerus (Caudocranial View) Same positioning as for shoulder/scapula Be aware of distortion since forearm is away from cassette

Humerus (Craniocaudal View) Use when extension above head cannot be achieved

Elbow (Mediolateral Extended View) ML Flexed View Move head & neck dorsally Affected elbow joint is in an extended position Extend other limb caudally (out of view) Maintain symmetry! May need to stabilize distal limb to keep anatomy parallel

Elbow (CrCa View) Pull head away from affected limb Center beam on center of humeral condyles Foam pad under unaffected limb Margins: proximal 1/3 of __________/_________ & distal 1/3 of _________________ * Same positioning for other CrCa views (with different borders)

Radius & Ulna (Mediolateral View) Same as for extended elbow view (with different margins) Place foam under the humerus & cranial thorax to maintain alignment Measure at mid-radius Margins: include entire elbow and carpal joint

Radius & Ulna (CrCa View) Positioning as for CrCd elbow view (with different borders) Measure at mid-radius Limb must be parallel Olecranon must sit in between lateral condyles Use tape to secure Head must be pulled out of view

Fracture of the Radius/Ulna

Fracture of the Radius/Ulna

Carpus (Mediolateral Hyperflexed View)

Carpus (Mediolateral Hyperflexed View) Lateral recumbency Hyperflex carpus Bring toes towards R/U Helps evaluate carpal joint laxity Margins: Proximal third of metacarpus to distal third of radius/ulna *Usually include the digits too

Foot (Mediolateral View) Separate digits with tape Tape the lateral phalanx and medial phalanx and pull apart Measure & center primary beam at site of interest Margins: carpus and everything distal Cassette can be split Point toes in same direction and collimate well!

Foot (Dorsopalmar View) Sternal recumbency Move head laterally Extend both forelimbs & secure affected limb proximally Place carpus flat on cassette Abduct the elbow slightly to straighten carpus Foam pad or rice sock next to elbow to prevent rotation. Flexed or stressed views may be useful in detecting joint instability. Use tape/wooden spoons

Foot (Dorsopalmar View)