SAS: Ortho Exam 3

Physical Exam

• Orthopedic → systematic

  • When: Observe before stress/pain

  • Look for: regional and gross 

    • Lameness, abnormal posture, gait, atrophy, behavior 

      • “sound is down” → forelimb headbob lameness

      • look at “Bad” leg last

      • 1st exam: awake, 2nd exam sedated

• Neuro

  • Look for: conscious proprioception

• Dt:

  • Non-Invasive: rads, CT, MRI (soft tissue), Scintigraphy 

  • Invasive: FNA / Biopsy, Arthrography, Arthrocentesis, Arthroscopy

Regional Examination of the Forlimb

• Digits & Metacarpal/Metatarsal Bones

  • Check each digit/nail bed and webbing

  • Pain, abnormal size, foreign material, draining tracts

  • Flex/extend phalangeal joints

    • Increased effusion: Tarsus (tarsocrural joint) – craniolateral and caudolateral

• Carpus

  • Effusion: radiocarpal joint (cranial)

    • Increased effusion: (radiocarpal joint) – cranial

      • Check collateral ligaments

• Long Bones (Radius/Ulna, Humerus)

  • Palpate systematically (avoid muscle belly pressure)

  • Look for atrophy, stiffness, swelling, proliferation, focal pain, neoplasia, panosteitis, HOD, HO, fractures

• Elbow: hinge joint

  • Effusion: caudomedial/caudolateral

    • pronation, supination

• Shoulder

  • Effusion: tricky

  • ROM: Check biceps tendon: cranial surface of joint

    • Abduction angle: medial collateral lig.

Regional Examination of the Hindlimb

• Tarsus

  • Effusion: tarsocrural joint (craniolateral, caudolateral)

  • ROM: Check Achilles tendon integrity

    • pronation, supination, varus, valgus

• Long Bones (Tibia/Fibula, Femur)

  • Palpate systematically (avoid muscle belly pressure)

  • Look for atrophy, stiffness, swelling, proliferation, focal pain, neoplasia, panosteitis, HOD, HO, fractures

• Stifle

  • Effusion: parapatellar

  • Collateral lig: Medial limits valgus, Lateral limits varus, patella tracking

• Hip

  • Effusion: rarely palpable

  • Ortolani maneuver (hip laxity; done under sedation)

  • Lumbosacral vs Hip Pain

    • Palpation: compression test

    • Standing exam: Take weight off legs, lateral

    • extension of limbs: iliopsoas pain (tightens w/ age)

    • Raise tail: flexes hip joint

    • Rectal exam: pressure dorsal to joint

Scintigraphy

• IV Radioactive substance (isotope)

• Localization of lameness

• ID avascular bone 

Computed Tomography (CT) vs. Magnetic Resonance Imaging (MRI)

• CT: Skull, spine, joints

  • 3D reconstruction

• MRI: Soft tissue

  • Cross-sectional and multiplanar anatomy

    • Articular cartilage

    • Ligaments

    • Joint capsule

    • Muscle and fascial planes

Arthrocentesis

• When: Performed after non-invasive imaging

• Why: confirm/categorize joint disease, monitor therapy

• Risks: infection

• Where:

  • Carpus (cranial, flexed)

  • Elbow (caudomedial/lateral)

  • Shoulder (lateral, distal to acromion)

  • Tarsus (craniolateral/caudolateral)

  • Stifle (parapatellar, flexed)

  • Hip (dorsal/craniodorsal, neutral)

• Synovial fluid analysis: color, turbidity, viscosity, bacteria

Normal Blood Supply of Long Bones

• Proper Nutrient artery: medullary cavity (30%), inner 2/3 cortical bone (70%)

  • Medullary circulation is mostly disrupted → fracture

• Metaphyseal arteries: proximal & distal metaphyseal

  • Hypertrophy if nutrient artery is damaged

• Periosteal arteries: outer 1/3 cortical bone

  • Primary circulation in fractures

• Epiphyseal arteries: supply epiphysis only (do not cross physis)

3 stages of fracture healing

• Inflammation

• Repair

• Remodeling

Inflammatory Phase of Bone Fracture Healing

• When: Immediate after fracture step 1

• How: 

  • Mediators: serotonin, histamine, thromboxane A, vasodilation, permeability

  • Hematoma: fibrin, platelets, clot → increased vascular permeability

  • Removal of necrotic osteocytes

  • New extraosseous blood vessels form

• Cs: swelling, erythema, pain, impaired fxn

Repair Phase of Bone Fracture Healing

• Step 2

• Necrotic tissue replaced with new cells/matrix

• Undifferentiated mesenchymal cells migrate to injury via inflammation

  •  bone, cartilage, vessels, fibrous tissue

• Callus formation: will form bone over time

  • Soft callus: cartilage (central) + fibrous tissue

  • Hard callus: bony (peripheral)

Remodeling Phase of Bone Fracture Healing

• Step 3

• Reorganization and reshaping of reparative tissue

• Callus → more ordered structure and resorbed 

• ↓ Cell density, ↓ vascularity = new bone formation

• Matrix fibrils align along stress lines

• Endochondral ossification → cartilage → bone

• Woven bone → lamellar bone : late stages 

  • parallel

Direct (Primary) Bone Healing

• Fracture ends in direct contact

• Requires rigid stability

• Osteoblasts cross fracture line → bone deposition

• No callus required

• Gap healing: Gap ≤ 150–300 µm minimal 

  1. Gap filled with fibrous bone @ fracture site

  2. Haversian remodeling: longitudinal bone

Indirect (Secondary) Bone Healing

• Occurs with instability

• Ends not in contact

• Requires callus formation

  • increased Motion = larger callus

  • Involves endochondral ossification

The 4 A’s of healing

• Apparatus: implant integrity

• Activity: evidence of bone formation/healing

  • Direct: fracture line becomes fuzzy

  • Indirect: callus

• Alignment of bone

• Apposition of repair

Complications of Bone Healing

• Dt: Take xrays every 4-6 weeks postop** compare pre/post op

• Delayed Union: Healing slower than expected, but evidence of healing present

  • Tx: wait, bone graft, stabilize, remove loose implants

• Nonunion: No progression on rads for 3+ months, instability, poor blood supply

  • Vascular (viable): callus present, fracture line persists

    • Tx: stabilize, remove implants, align

  • Avascular (non-viable): little/no callus, poor biology 

    • Tx: curettage, rigid fixation, cancellous graft, remove loose implants

• Malunion: Fracture healed in abnormal alignment

  • Varus: distal limb deviates medially: elbow/knee away

  • Valgus: distal limb deviates laterally: elbow/knees touching

  • Torsion: bone rotated on long axis

  • Translation: displacement, longitudinal axis intact

  • Recurvatum: apex caudal, distal limb cranial to fracture

  • Procurvatum (antecurvatum): apex cranial, distal limb caudal to fracture

• Wolff’s Law: bone remodels along stress lines 

  • explains partial correction of malunion

Bone Grafting Materials

• placed into spaces around a fracture, or within defects in bone

• Autograft (auto): donor = recipient (same animal)

  • best osteogenic potential

• Allograft: donor = same species

• Xenograft: donor = different species 

  • less useful in ortho

• Cortical: strong, structural support; osteoconduction only, min osteoinduction (banked, avascular, acellular)

  • risk of sequestrum with infection

• Cancellous: highly cellular, weak mechanically; provides osteogenesis + induction + conduction (freah/frozen, high cellular)

• Corticocancellous: mix (ribs, iliac crest, ulna) (chunk)

• Synthetic: calcium phosphate, bioactive glass

Bone Graft Procedure

• Why: Delayed union, nonunion, arthrodesis, osteotomies, high-risk fractures, segmental replacement, fill defects or cavities

  • Osteogenesis: direct new bone formation by grafted osteoblasts

  • Osteoinduction: stimulates progenitor cell proliferation (BMPs)

  • Osteoconduction: scaffold for new bone growth

  • Osteopromotion: enhances osteoinduction

• Sites: proximal humerus, wing of ilium, proximomedial tibia, distal femur, proximolateral femur

• How: Harvest only when ready, use separate instruments if infection, store in blood (not saline)

• Risk: Infection, donor site seeding, neoplasia, donor site morbidity (pain, fracture, seroma, dehiscence)

General Principles of Fracture Management and Repair

• Evaluate, describe fracture, and plan 

  • Open: Antibiotics asap, analgesia, cover, immobilize

    • Broad spec (ampicillin/sulbactam) intra/post-op

    • URGENT

  • Closed: Immobilize, analgesia, stabilize before repair 

    • Cefazolin q90 min intra-op only

    • Not urgent

  • Joint involvement: urgent 

  • Fixation: load sharing, control forces, maintain alignment 

  • Implant: tension surface > compression surface

• Ensure peripheral nerves are intact: radial, sciatic

• Skin prep: Clip after induction

  1. #1 source of infection = patient’s own skin

• Perform surgery

• Evaluate: rads q4-6w; alignment, apparatus integrity, activity of healing, apposition

Fracture Classification

• Location: 

  • Spine, skull, joints: require special imaging (CT, oblique, stress views)

  • Long bones: Epiphysis, Physis (growth plate), Metaphysis, Diaphysis, Articular

    • Salter-Harris = Physeal Fractures

      • Common in young animals (open physes)

• Gustilo/Anderson Grading system: Open fractures!

  • Grade I: inside-out, puncture <1 cm, clean

• Grade II: wound >1 cm, mild soft tissue trauma, no flaps

• Grade III: extensive trauma, skin loss, exposed bone

Describe the Fracture

• Forces: Tension, compression, bending, torsion, shear

• Pattern: Transverse, Oblique, Spiral, Comminuted

Physeal fractures

• Young animals, open growth plates

Fracture Forces

• Load sharing

  • Balance with degree of fixation and soft tissue damage

  • Plate should absorbs most the energy

• Implant location

  • Tension surface **

  • Compression surface(weight is applied)

GOAL: • Appropriate fracture healing • Restoration of function

Halstead’s principles

• Gentle tissue handling

• Control hemorrhage

• Maintain strict asepsis

• Preserve blood supply

• Eliminate dead space

• Accurate tissue apposition

External Coaptation

• Why: Immobilization, support, protect, analgesia, compression 

  • Limb fractures, lig instability, pre/post-op support, swelling, luxation

• How: Bandages and slings 

  • Avoid excessive tightness: 2° & 3° layers

  • circulation risk

  • Always include joint above & below

  • Always allow visualization of 3/4 digits

• Risk: Bandage sores, necrosis, slippage, nonunion

Bandage Components

• Tape stirrups: adhesive strips for stability

• Primary layer: non-adherent dressing 

  • protects wounds

• Secondary layer: cast padding or rolled cotton

  • Protects tissue, relieves pain, immobilizes limb

• Tertiary layer: cling gauze + Vetwrap/Elasticon

  • Compression & protection

Robert Jones Bandage

• Big and bulky!! - most compression

• Why:Temp distal limb splint for below elbow/stifle

  • compression, immobilization, reduces swelling, dead space, pain, protect

• How:

  • Cover with non-adherent dressing

  • Tape stirrups applied cranial/caudal or medial/lateral

  • Limb held in extension

  • x2 Rolled cotton(LG) or cast padding 3-6 layers layer(SM)

    • Apply each layer with 50% overlap, tight as possible

  • x2 Cling gauze (compression) layer

  • Fold stirrups over bandage

  • Vetwrap/Elasticon (compression) layer

    • gentle pressure

• Check: “thump like a watermelon”

  • Toe alignment 

Modified Robert Jones Bandage

• Why: Less bulk, immobilization, compression, support

• How:

  • Cover with non-adherent dressing

  • Tape stirrups applied cranial/caudal or medial/lateral

  • Limb held in standing angle

  • 3-4 layers cast padding only

    • NO rolled cotton

  • Cling gauze (compression) layer

  • Fold stirrups over bandage

  • Vetwrap/Elasticon (compression) layer

Splint Bandage

• Why: Temp immobilization, support post-op, definitive for mod stable fracture, money constraints

  • No compression = not for swollen limbs

• Types:

  • Distal limb: below elbow/stifle

  • Spica: proximal limb, extends to opposite hip/shoulder 

  • Malleable: metal rods, thermoplastics, padded metal, cast tape

  • Rigid: preformed plastic/metal

• Common complication: rub sores, monitor pressure points!!

Casts

• Why: definitive fracture stabilization 

  • indirect bone healing

  • Fractures are closed, stable (not axial), distal to elbow/stifle, heal quickly!!

• How:

  • Limb immobilized

  • Closed reduction of fracture

  • Tape stirrups → stockinette! → casting tape 

    • 2-4 layers, 50% overlap

• Check: 

  • Rads with >50% reduction needed min

  • Common complication: rub sores, monitor pressure points!!, weekly checks

• Removal: bivalve or saw/spreader

  • Bivalve: cast can be reused, cut once they are formed for easy cast changes!! 

Ehmer Sling

• Why: maintain reduction of craniodorsal hip luxation

  • abducts + internally rotates hip putting femur into acetabulum

• How:

  • Under anesthesia, reduce hip first

  • Elasticon tape applied around metatarsals across dorsum to opposite hip

    • Keep metatarsal wrap loose (avoid swelling)

  • Repeat multiple times

• Removal: after 10-14 days

Velpeau Sling

• Stabilizes shoulder with medial dislocation

• Supports scapular fractures

• Prevents weight-bearing

Intramedullary Pins

• Why: Controls bending, Strength ∝ radius⁴

  • NOT effective against rotation or axial loading

• Where: femur, tibia, ulna, humerus

  • NOT for radius!!!

• Type: 

  • Primary stabilizer: 60-70% diameter of medullary canal

    • big and bulky

  • Adjunct stabilizer: 30-40% diameter of medullary canal

    • smaller pin

  • Texture: smooth > threaded(don’t use)

• How: 

  • Adjunct fixation: required; plate/screws, cerclage, external fixator

    • Exception is physeal fractures in young dogs (can be sole implant)

Intramedullary Pins insertion

• Insertion: 

  • Retrograde: fracture site → out epiphysis → repositioned → across fracture

    • Ulna: retrograde; canal is narrow distally

    • Humerus: normograde OR retrograde; proximolateral → distomedial

  • Normograde: proximally → down medullary canal → across fracture

    • Femur: normograde, ↓ sciatic/physis risk; start at trochanteric fossa

    • Tibia: normograde ONLY; start at tibial crest 

      • medial, ~⅓ distance caudal to joint line, near patellar tendon

    • Humerus: normograde OR retrograde; start proximolateral → end distomedial (avoid fossa)

Cross Pins

• Why: physeal fractures 

  • femur, tibia

• What: Small smooth IM pins

• How: inserted laterally, cross physis and eachother

Cerclage Wire

• What: Stainless steel 18–22 gauge

• Why: adjunctive, long oblique fracture (>2× diameter)

  • never sole fixation

• How: Fully encircles bone

  • Anatomical reduction

  • Use ≥ 2 wires perpendicular to fracture line

    • Closest wire 3-5 mm from fracture

    • Wires ~1 cm apart (closer is better)

Screws

• Classified: by outer diameter

• Types: Stainless steel or titanium, partially or fully threaded, Locking vs. non-locking

  • standard Non-locking: rely on bone–plate friction

  • Locking: screw head threads into plate, plate/screw interface

    • fixed-angle stability

  • Individual: lag screw 

Plates

• What:

  • Round (compression) or oval holes @ fracture line

  • Dynamic compression plate (DCP)

  • Limited-contact DCP (LC-DCP)

  • Locking plates: rigid plate-screw interface, for poor bone quality, less contouring needed

• Why: 

  • Compression: transverse fractures (plate/screws)

  • Neutralization: protects adjunct fixation (lag screw/cerclage + plate/screws)

  • Buttress: plate carries full load for unstable fracture

• How:

  • Apply to tension surface of bone

  • Must engage ≥6 cortices on each side of fracture!!

Interlocking Nail

• What: IM pin + locking bolts proximal and distal

  • IM pin controls bending

  • Bolts control shear & rotation

• Why: femur, tibia, humerus: limited to

  • $$, technically demanding, specialized

• How: 

  • Fills 80-90% of medullary canal

  • Place proximal and distal of break

Tension Band Wiring

• primary distractive forces

• Why: Converts distractive into compressive forces

  • Patellar, Traction physeal, Olecranon fractures, Tibial crest avulsion

• What: Kirschner wires + figure-of-eight cerclage wire (18-22g)

External Skeletal Fixation

• Why: Long bone fractures, Arthrodesis, Spinal stabilization, Mandibular fractures, Distraction osteogenesis

• What: Pins, Clamps, Connecting bar

  • Use threaded pins, Lg size possible (25% diameter of bone)

• How: use the simplest frame design that will work

  • Place 3-4 pins per main fragment, evenly, and perpendicular to long axis of bone along safe corridors

    • Safe corridors: distal radius/ulna, tibia/fibula

      • Femur has NONE

  • Connecting bar placed 1-2 cm from bone

  • Clamp interface inside connecting bar

• Risk: infection, neurovascular injury, breakage/loosening, loss of reduction, necrosis, delayed union, iatrogenic fracture

Safe corridors

• Safe corridors: distal radius/ulna, tibia/fibula

  • Femur has NONE

• Tibia: medial

• Humerus: lateral

• Radius: medial

Fixation Pins

• Class: thread location

  • Half pin and Full pin

• Types:

  • Smooth (Steinmann pin, Kirschner wire)

    • ↓ Pullout strength

    • ↑ Susceptibility to cyclic loading

    • ↑ Premature loosening

  • Threaded

    • Positive: threads rolled, strong

    • Negative: threads cut, weak

    • Tapered end improves strength

Types of External Skeletal Fixation

• What: 

  • Pins: Engage bone, provide stabilization

  • Clamps: Secure pins to connecting bar.

  • Connecting bar: Links clamps and pins.

• Types: 

  • Linear: Frame strength ↑ with complexity

    • Type IA: Unilateral, uniplanar

    • Type IB: Unilateral, biplanar

    • Type II: Bilateral, uniplanar

    • Type III: Bilateral, biplanar

  • Hybrid ring 

    • Why: fractures with small bone fragments

    • What: Combo half pins + ring with small fixation wires

  • Circular

    • What: Kirschner wires + rings + connecting bars

    • Why: comminuted fractures, angular limb deformities

Linear Type 1/A ESF

• ½ pins

• Unilateral, uniplanar

  • all pins enter one 1 side

  • all pins going in the same plane (medial→lateral)

Linear type 1B ESF

• ½ pins

• Unilateral, biplanar 

  • different planes

Linear type 2 ESF

• Full pins

• Bilateral, uniplanar

  • same plane (medial → lateral)

Linear type 3 ESF

• full pins and ½ pins

• bilateral, biplanar

  • type 1+2

  • different planes 

• Frame strength increases as frame complexity increases

Scapular Fractures

• Body & Spine

  • Minimally displaced: stable, Velpeau sling 2-3w

  • Comminuted or Transverse: unstable, internal fixation**

    • can fold on itself

• Supraglenoid Tuberosity

  • Et: immature dogs, avulsion/physeal separation from biceps pull

  • Tx: pin + tension band, or lag screw

• Neck & Glenoid Cavity

  • Tx: reconstruction required, cross pins, lag screw

Humeral Fractures

• spica splints required!

• Considerations: 

  • Radial n.: lateral/superficial to brachiali muscle

• Proximal Physeal Fractures

  • Sig: growing dogs

  • Tx: parallel K-wires, cross the physis, heals fast

• Diaphyseal Fractures

  • Tx: fxn alignment

    • Spiral: plate + screws, or IM pin + cerclage 

      • pin sized to distal canal; normograde/retrograde; lateral → medial

    • Transverse: plate + screws, IM pin

    • Comminuted: plate + screws + IM pin, buttress, external fixator

• Condylar Fractures: Lateral > medial

  • Sig: Young dogs w/ Salter-Harris IV, older dogs w/ incomplete ossification of humeral condyle

  • Tx:

    • Lateral condyle: lag screw + anti-rotational K-wire

    • T or Y fracture: bilateral plates + screws

Radius & Ulna Fractures

• Considerations: No soft tissue envelope, weight-bearing, blood supply poor in small breeds, poor healing, Robert/modified jones bandage

• Tx: rigid fixation, often only radius tx

  • Bone plate & screws (#1)

    • IM pins contraindicated for radius

  • IM pins NOT in radius (cats need both)

  • JUST the radius in fixed(dogs)

  • External skeletal fixation→ open fractures, 1A ESF

  • Casting: acceptable if 50% reduction; best for transverse fractures in young dogs

    • NOT in toy breeds

Pathologic Fractures

• Et: neoplasia, fungal osteomyelitis

• Tx: Repairable if limb, adjunctive therapy

• Px: Same as underlying disease

Carpal, Metacarpal, Digital, Metatarsal Fractures

• Very common, greyhounds

• Carpal: lag screw

• Metacarpal and Metatarsal: medical tx most common

  • Tx: closed reduction + caudal splint (Rx #1), IM pins/plates + caudal splint (Sx)

    • Sx indicated if open, grossly displaced, intra-articular, or all 4 fractured

• Digital: caudal splint bandage for 6w

Pelvis Fractures

• Considerations: Multi physes, normally breaks at multi sites 

  • Sciatic n.: through ischiatic notch

  • Weight transfer: paw → tibia → femur → acetabulum → ilium → SI joint

• Et: males > females, trama

• Dt: Rads, CT for complex fractures/Sx planning

• Tx: 

  • Rx: non-displaced, unilateral, non-articular, non-weight-bearing fractures

    • 6 w crate rest, sling, pain control, controlled walks, PT

  • Sx: ilium/acetabulum/SI joint (weight-bearing), bilateral fractures, displacement, colon compromise, pelvic canal compromise (parturition), sciatic entrapment

    • Ilium: plate + screws

    • Acetabulum: plate + screws, cross pins, PMMA

    • SI joint: screw stabilization

Femur Fractures

• Capital Physis: Salter-Harris I, skeletally immature

  • Dt: AP & frog-leg radiographs

  • Tx: K-wires (diverging/parallel), temp“apple-coring” due to pins and blood supply

• Patellar fractures: uncommon, direct blow

  • Apical (<1/3 patella): excision

  • Multifragmentary: patellectomy

  • Transverse (#1): wire + tension band

• Greater Trochanter Avulsion: Young, gluteal muscle traction

  • Tx: pin + tension band

• Diaphyseal fractures (#1)

  • Tx: plate + screws, interlocking nail, IM pin + cerclage

    • ESF not recommended as no safe corridors

    • Compartment syndrome: muscles feel like rock

• Distal Physeal fractures: young, Salter-Harris type, growth plate involvement

  • Tx: cross pins (linear), plates (if comminuted)

    • Risk of quadriceps contracture(esp. extended postion) peg leg

Tibia & fibula Fractures

• Considerations: Common, Min soft tissue envelope, risk of open fracture

  • fibula broke concurrently, not broke in young 

• Tx:

  • Rx: Casting/splinting 

    • closed, transverse fractures, >50% reduction, lateral splint (greenstick fractures)

  • Sx: Plate + screws, IM pin + cerclage, Interlocking nail, ESF

    • Avulsion: tension band + K-wire, or K-wires alone

    • Physeal: urgent fixation, cross pins

      • younger animals

Fractures of the Mandible and Maxilla

• Check occlusion!!

• Considerations: 

  • Body: bending forces, tension greatest at alveolar surface

  • Ramus: shear forces

  • Symphysis/Incisive region: rotational forces

• Et: Trauma, severe dental disease, neoplasia

  • Mandibular: Dogs body and cats incisor region

  • Maxillary: Dogs alveolar region and cats midline palate separation

• Dt: Rads, CT for surgical planning

• Comp: Dental issues, malocclusion, facial deformity, oronasal fistula, palate defects, osteomyelitis, bone sequestration, delayed union/non-union

Treatment for Fractures of the Mandible and Maxilla

• Keep teeth for stability & occlusion, strong fixation and tension at alveolar surface, pharyngostomy intubation

• Non-surgical:

  • Tape muzzle: cheap, easy, unilateral stable fractures

    • not good for cats/brachycephalics

  • Symphyseal wiring: cats, cerclage wire between canines, 6-8w healed

  • Maxillomandibular bonding: bonds upper/lower canines, cats/brachycephalics

    • aspiration risk, slurry diet needed

  • Interdental splinting: acrylic/wire splinting, good for rostral, requires stable teeth

• Surgical:

  • Interfragmentary wiring: good for linear, 2-piece fractures, requires exact reduction

  • not good for comminution/bone loss

  • Plates & screws: body/ramus, avoid tooth roots & mandibular canal, place ventrolaterally

    ESF: strong, min invasive, high postop care, self-trauma risk