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 Bone and Soft-Tissue Disorders

= soft-tissue injury with break in continuity of bone or cartilage

General description:

  1. OPEN / CLOSED
    open Fx = communication between fractured bone + skin
  2. COMPLETE / INCOMPLETE
    complete Fx = all cortical surfaces disrupted
    incomplete Fx = partial separation of bone
    Incomplete pediatric fractures:
    1. longitudinal compressive force:
      • buckle / torus Fx
      • bowing Fx = plastic deformity of thin long bone (ulna >clavicle, fibula)
    2. force perpendicular to long axis of bone greenstick Fx
    3. combination fracture lead-pipe Fx = combination of greenstick + torus Fx
  3. SIMPLE / COMMINUTED
    simple Fx = noncomminuted
    comminuted Fx = >2 fragments
    segmental Fx = isolated segment of shaft
    butterfly fragment = V-shaped fragment not completely circumscribed by cortex
  4. DIRECTION OF FRACTURE LINE relative to long axis of bone:
    • transverse, oblique, oblique-transverse, spiral

Special terminology:

Description of anatomic positional changes:

= change in position of distal fracture fragment in relation to proximal fracture fragment

LENGTH = longitudinal change of fragments

DISPLACEMENT = latitudinal change of anatomic axis

ANGULATION / TILT

= long axes of fragments intersect at the fracture apex:

eg, “ventral angulation of fracture apex”

eg, “in anatomic / near anatomic alignment”

ROTATION

NUC:

Typical time course:

  1. Acute phase (3–4 weeks) abnormal in 80% <24 hours, in 95% <72 hours
    • Elderly patients show delayed appearance of positive scan
    • broad area of increased tracer uptake (wider than fracture line)
  2. Subacute phase (2–3 months) = time of most intense tracer accumulation
    • more focal increased tracer uptake corresponding to fracture line
  3. Chronic phase (1–2 years)
    • slow decline in tracer accumulation
    • in 65% normal after 1 year; >95% normal after 3 years

Return to normal:

  1. Simple fractures: 90% normal by 2 years
  2. Open reduction / fixation: <50% normal by 3 years
  3. Delayed union: slower than normal for type of fracture
  4. Nonunion: persistent intense uptake in 80%
  5. Complicated union (true pseudarthrosis, soft-tissue interposition, impaired blood supply, presence of infection)
    • intense uptake at fracture ends
    • decreased uptake at fracture site
  6. Vertebral compression fractures: 60% normal by 1 year; 90% by 2 years; 97% by 3 years

Pathologic Fracture  !!navigator!!

= fracture at site of preexisting osseous abnormality

Cause: tumor, osteoporosis, infection, metabolic disorder

Stress Injury (Fracture)  !!navigator!!

= fracture produced as a result of repetitive prolonged muscular action on bone exceeding its capability for self-repair

Insufficiency Fracture

= normal physiologic stress applied to bone with abnormal elastic resistance / deficient mineralization

Cause:

  1. Osteoporosis
  2. Renal osteodystrophy

    Types of Fractures

    TypeBone QualityLoad
    Traumaticnormalsingle large
    Fatigue (stress)normalrepetitive
    Insufficiency (stress)abnormal (metabolic)minimal
    Pathologicabnormal (tumor)minimal
  3. Osteomalacia / rickets
  4. Hyperparathyroidism
  5. Radiation therapy
  6. Rheumatoid arthritis
  7. Paget disease
  8. Fibrous dysplasia
  9. Osteogenesis imperfecta
  10. Osteopetrosis
  11. Prolonged corticosteroid treatment
  12. Tumor treatment with ifosfamide, methotrexate

Location: thoracic vertebra, sacrum, pubic bone, ilium, lower extremity (calcaneus, tibia, fibula)

Fracture orientation: perpendicular to long axis of bone

Plain film / CT (1–2 weeks after onset of fracture):

  • often normal in early stage of fracture
  • cortical linear lucency ← disruption (= fracture line)
  • localized cortical thickening
  • periosteal new bone formation
  • medullary sclerosis (endosteal callus formation)

MR:

  • zone of low SI on T1WI + variable intensity on T2WI (= discrete fracture line)
  • surrounded by diffuse marrow edema (hypointense on T1WI + hyperintense on T2WI) = stress reaction
  • circumferential periosteal reaction + early callus + surrounding edema adjacent to bone hyperintense on T2WI + enhancement after IV Gd-chelate (DDx: osteomyelitis with more eccentric involvement)

NUC (bone scan):

  • increased abnormal uptake

Pelvic Insufficiency Stress Fracture

  • severe pain in lower back + sacroiliac joints; radiates to buttocks, hips, groin, legs; worsens with weight bearing
  • walking ability impaired

Prevalence: 1.8–5% of women >55 years

Predisposed: postmenopausal women

Location: sacral ala, parasymphyseal region of os pubis, pubic rami, supraacetabular region, iliac blades, superomedial portion of ilium

Types:

  1. occult fracture:
    Site: sacrum >supraacetabulum, ilium
    • sclerotic band, cortical disruption, fracture line
    • Often obscured by overlying bowel gas + osteopenia!
  2. aggressive fracture:
    Site: parasymphysis, pubic rami
    • exuberant callus formation, osteolysis + fragments ← prolonged / delayed healing / chronic nonunion

    CAVE: fracture may be misdiagnosed as neoplasm; interpretation also histologically difficult

NUC:

  • butterfly / H-shaped (“Honda” sign) / asymmetric incomplete H-shaped pattern of sacral uptake
  • pelvic outlet view for parasymphyseal fx

CT and MR (most accurate modalities):

  • sclerotic band, linear fracture line, cortical disruption, fragmentation, displacement
  • bone marrow edema
  • Excludes bone destruction + soft-tissue masses!

Prognosis: healing in 12–30 months

Femoral Insufficiency Fracture

Site: subcapital

  • subtle femoral neck angulation
  • trabecular angulation
  • subcapital impaction line

Fatigue (Stress) Fracture

= normal bone subjected to repetitive stresses (none of which is singularly capable of producing a fracture) → leading to mechanical failure over time

Risk factors: new / different / rigorous repetitive activity; female sex; increased age; Caucasian race; low bone mineral density; low calcium intake; fluoride treatment for osteoporosis; condition resulting in altered gait

  • activity-related pain abating with rest
  • constant pain with continued activity
  • infraction in the center of an area of cortical thickening
  • extensive bidirectional cortical thickening from endosteum to periosteum
  • focal cortical ridge

NUC:

  • linear intense uptake of tracer

DDx: Osteoid osteoma (round nidus, no cortical ridge, “double-density” sign on bone scan)

  • Spine
    1. Clay shoveler's fracture: spinous process of lower cervical / upper thoracic spine
    2. Spondylolysis = pars interarticularis of lumbar vertebra: ballet, gymnastics, diving
    3. Ribs: carrying heavy pack, golf, coughing
  • Pelvis
    1. Obturator ring of pelvis: stooping, bowling, gymnastics
      Site: superior / inferior pubic ramus
    2. Sacrum (<2%): long-distance runner, military recruits
      Site: unilateral ? ← leg length discrepancy
  • Upper extremity
    1. Clavicle: postoperative (radical neck dissection)
    2. Coracoid process of scapula: trap shooting
    3. Coronoid process of ulna: pitching ball, throwing javelin, pitchfork work, propelling wheelchairs
    4. Distal shaft of humerus: throwing ball (basketball, baseball, softball, javelin)
    5. Hook of hamate: swinging golf club / tennis racquet / baseball bat
    6. Other wrist bones: capitate >lunate >scaphoid
  • Lower extremity
    1. Femur
      • neck: ballet, long-distance running
        Site: inferior surface of medial femoral neck
        • subtle lucency / sclerosis (= acute fracture)
        • lucent line surrounded by sclerosis (= subacute fracture)
      • shaft: ballet, marching, long-distance running, gymnastics
      • distal metaphysis: endurance athlete (runner, soccer player, triathlete)
    2. Patella: hurdling
    3. Tibial shaft:
      • proximal diaphysis: running
      • middle + distal diaphysis: football, soccer, tennis, ballet, jogging
      • Shin splint = early stress response
    4. Fibula (distal diaphysis): long-distance running, jumping, parachuting
  • Foot (in order of frequency):
    1. 2nd>3rd + 4th metatarsal: marching, stomping on ground, prolonged standing, ballet, long-distance running, postoperative bunionectomy
    2. Calcaneus: jumping, parachuting, prolonged standing, long standing, recent immobilization
      • vertical / oblique fracture orientation anterior to tuberosity
    3. Tarsal navicular: stomping on ground, marching, long-distance running, prolonged standing, ballet
      • vertically oriented fracture in midbody
      • Midfoot fractures are difficult to diagnose by conventional radiography; CT + MRI are often helpful
    4. Sesamoids of metatarsal: prolonged standing, gymnastics, long jumping

X-RAY (15% sensitive in acute fractures, increasing to 50% on follow-up):

  • cancellous (trabecular) bone (notoriously difficult to detect)
    • subtle blurring of trabecular margins
    • faint sclerotic radiopaque area of peritrabecular callus (50% change in bone density needed)
    • sclerotic band (← trabecular compression + callus formation) usually perpendicular to cortex
  • compact (cortical) bone
    • “gray cortex” sign = subtle ill definition of cortex
    • intracortical radiolucent striations (early)
    • solid thick lamellar periosteal new bone formation
    • endosteal thickening (later)
  • Follow-up radiography after 2–3 weeks of conservative therapy

NUC (no longer “gold standard” compared with MR):

  • Highly sensitive with low specificity + ineffective in early cortical stress injuries
  • abnormal uptake within 6–72 hours of injury (prior to radiographic abnormality)
  • “stress reaction” = focus of subtly increased uptake
  • focal fusiform area of intense cortical uptake
  • abnormal uptake persists for months

MR (very sensitive modality; fat saturation technique most sensitive as it detects an increase in water content of medullary edema / hemorrhage):

  • increased marrow SI on T2WI + STIR (extensive micro- fractures cause edema + hemorrhage, which may obscure the fracture line); resolves within 6 months in 90%
  • low-intensity band contiguous with cortex on T2WI = fracture line of more advanced lesion
  • diminished marrow SI on T1WI of fracture line (less helpful)
  • periosteal edema = hyperintense line along periosteal surface on T2WI

CT (best modality for cortical abnormalities):

helpful in: longitudinal stress fracture of tibia; in confusing pediatric stress fracture (to detect endosteal bone formation)

  • cortical abnormalities:
    • osteopenia = increased hypoattenuation
    • resorption cavities = round / oval hypoattenuating intracortical defect
    • striations = subtle hypoattenuating intracortical lines

DDx:

  1. Shin splints (activity not increased in angiographic / blood-pool phase)
    • long linear uptake on posteromedial (soleus muscle) / anterolateral (tibialis anterior muscle) tibial cortex on delayed images (from stress to periosteum at muscle insertion site)
  2. Osteoid osteoma (eccentric, nidus, solid periosteal reaction, night pain)
  3. Chronic sclerosing osteomyelitis (dense, sclerotic, involving entire circumference, little change on serial radiographs)
  4. Osteomalacia (bowed long bones, looser zones, gross fractures, demineralization)
  5. Osteogenic sarcoma (metaphyseal, aggressive periosteal reaction)
  6. Ewing tumor (lytic destructive appearance with soft-tissue component, little change on serial radiographs)

Apophyseal Injury = Avulsion Fracture  !!navigator!!

Mechanism: excessive avulsive force

◊Physis under secondary ossification center is weakest part!

At risk: young athletes: hurdlers, sprinters, cheerleaders (repetitive to and fro adduction / abduction + flexion / extension)

Age: children >adults

Avulsion injury of lesser trochanter in adults suggests underlying malignant disease

  • pain, point tenderness, swelling
  • physeal widening
  • irregularity at site of avulsion
  • displaced pieces of bone of variable size:
    • crescentic ossific opacity if viewed on tangent
    • very subtle disk-shaped opacity if seen en face
  • abnormal foci of heterotopic ossification (later)
  • prominent bone formation in chronic avulsion injury from overuse with repeated microtraumas

DDx of healing acute injury: osteomyelitis, Ewing sarcoma

Overuse Injury to Physis  !!navigator!!

Little League Shoulder

= overuse injury to proximal humeral physis

Mechanism: excessive overhead throwing

Apophyseal Avulsion Injuries

LocationMuscle Origin / Insertion
Iliac crestabdominal musculature
Anterior superior iliac spinesartorius muscle + tensor fasciae latae m.
Anterior inferior iliac spinerectus femoris muscle
Symphysis pubis + inferior pubic ramuslong + short adductors, gracili
Ischial tuberosityhamstrings
Lesser trochanteriliopsoas muscle
Greater trochantergluteus medius + minimus, internal obturator, gemellus, piriformis
Inferior pole of patellapatellar tendon
Tibial tuberositypatellar tendon
  • widening + irregularity of proximal humeral physis

Little League Elbow

= traction injury of medial humeral epicondyle

Mechanism: pitching → valgus stress of cocking and acceleration

  • localized bone marrow edema
  • widening of physis

Gymnast Wrist

Mechanism: repetitive weight bearing on wrist

  • physeal stress changes of distal radius ± ulna
  • positive ulnar variance ← abnormal distal radial growth

Cx: strain / tear of triangular fibrocartilage complex

Epiphyseal Plate Injury  !!navigator!!

Prevalence: 6–18–30% of bone injuries in children <16 years

Peak age: 12 years

Location: distal radius (28%), phalanges of hand (26%), distal tibia (10%), distal phalanges of foot (7%), distal humerus (7%), distal ulna (4%), proximal radius (4%), metacarpals (4%), distal fibula (3%)

Mechanism: 80% shearing force; 20% compression

Resistance to trauma: ligament >bone >physis (hypertrophic zone most vulnerable)

MR:

  • focal dark linear area (= line of cleavage) within bright physis on gradient echo images (GRE)

Cx:

  1. progressive angular deformity from segmental arrest of germinal zone growth with formation of a bone bridge across physis = “bone bar”
  2. limb length discrepancy from total cessation of growth
  3. articular incongruity from disruption of articular surface
  4. Bone infarction in metaphysis / epiphysis

Salter-Harris Classification:

(considering probability of growth disturbance)

[Robert Bruce Salter (1924–) and W. Robert Harris (1922–), orthopedic surgeons in Toronto, Canada]

◊Prognosis is worse in lower extremities (ankle + knee) irrespective of Salter-Harris type!

mnemonic: SALTR

  • S lip of physis = type 1
  • A bove physis = type 2 (distal)
  • L ower than physis = type 3 (proximal)
  • T hrough physis = type 4
  • R ammed physis = type 5

Salter Type 1 (6–8.5%)

= slip of epiphysis (← shearing force separates epiphysis from physis)

Line of cleavage: confined to physis

Location: most commonly in phalanges, distal radius (includes: apophyseal avulsion, slipped capital femoral epiphysis)

  • widening of growth plate
  • displacement of epiphyseal ossification center

Prognosis: favorable irrespective of location

Salter Type 2 (73–75%)

= shearing force splits growth plate

Line of fracture: through physis + extending through margin of metaphysis separating a triangular metaphyseal fragment (= “corner” sign)

Location: distal radius (33–50%), distal tibia + fibula, phalanges

Prognosis: good, may result in minimal shortening

Salter Type 3 (6.5–8%)

= intraarticular fracture, often occurring after partial closure of physis

Line of fracture: vertically / obliquely through epiphysis + extending horizontally to periphery of physis

Location: distal tibia, distal phalanx, rarely distal femur

  • epiphysis split vertically

Prognosis: fair (imprecise reduction leads to alteration in linearity of articular plane)

Salter Type 4 (10–12%)

Location: lateral condyle of humerus, distal tibia

  • fracture involves metaphysis + physis + epiphysis

Prognosis: guarded (may result in deformity + angulation)

Triplane Fracture (6%)

Location: distal tibia, lateral condyle of distal humerus

  • vertical fracture of epiphysis + horizontal cleavage plane within physis + oblique fracture of adjacent metaphysis

Salter Type 5 (<1%)

= crush injury with injury to vascular supply

Location: distal femur, proximal tibia, distal tibia

Often associated with: fracture of adjacent shaft

  • no immediate radiographic finding
  • shortening of bone + cone epiphysis / angular deformity on follow-up

Prognosis: poor (impairment of growth in 100%)

Scapula Fracture  !!navigator!!

Most scapular fractures are minimally displaced extraarticular fractures of the scapular body, acromion, or coracoid process. Fractures of the glenoid neck or articular surface are more likely to require surgical repair.

= rare <1% of all extremity fractures

Mechanism: high-energy chest trauma

In 90% associated with: injury to chest, spine, pelvis, internal organs, brachial plexus, axillary vessels

Proximal Humerus Fracture  !!navigator!!

= may consist of up to 4 parts (fragment displaced by ≥1 cm / angled by ≥45°)

  1. anatomic head
  2. metaphyseal fragment with lesser tuberosity
  3. metaphyseal fragment with greater tuberosity
  4. humeral shaft

Prognosis: anatomic neck fractures are associated with an increased risk of avascular necrosis. The PPV is 97% if combined with a medial metaphyseal fragment <8 mm short and >2 mm displaced.

Neer classification (1970):

  • 1-part fracture (85%) = no displacement / angulation
  • 2- / 3- / 4-part fracture (15%)

Elbow Fracture  !!navigator!!

Pediatric Elbow Fracture

Age: common at 2–14 years

  • Soft-tissue
    • displacement of anterior + posterior fat pads (= elbow joint effusion with supracondylar / lateral condylar / proximal ulnar fractures)
    • displaced supinator fat pad (= fracture of proximal radius)
    • focal edema medially (= medial epicondyle fx) / laterally (= lateral condyle fx)
  • Humerus (80%)
    Supracondylar fracture (55%)
    • Mechanism: hyperextension with vertical stress
    • transverse fracture line
    • distal fragment posteriorly displaced / tilted
    • anterior humeral line intersecting anterior to posterior third of capitellum (on lateral x-ray)

    Lateral condylar fracture (20%)
    • Mechanism: hyperextension with varus stress
    • fracture line between lateral condyle + trochlea / through capitellum

    Medial epicondylar fracture (5%)
    • Mechanism: hyperextension with valgus stress
    • avulsion of medial epicondyle (by flexor muscles of forearm)
    • may become trapped in joint space (after reduction of concomitant elbow dislocation)
  • Radius (10%)
    Mechanism: hyperextension with valgus stress
    • Salter-Harris type II / IV fracture
    • transverse metaphyseal / radial neck fracture

    Mechanism: hyperextension with varus stress
    • dislocation as part of Monteggia fracture (from rupture of annular ligament)
  • Ulna (10%)
    • longitudinal linear fracture through proximal shaft
      Mechanism: hyperextension with vertical stress
    • transverse fracture through olecranon
      Mechanism: hyperextension with valgus / varus stress; blow to posterior elbow in flexed position
    • coronoid process avulsion
      Mechanism: hyperextension-rotation associated with forceful contraction of brachial m.

Elbow Dislocation  !!navigator!!

2nd most common joint dislocation in adult after shoulder

  1. Posterior elbow dislocation
  2. Anterior dislocation (rare): most often in child as a result of rebound following posterior dislocation

Associated soft-tissue injury (in sequence): lateral → medial

  1. Lateral collateral ligament complex
  2. Joint capsule + other lateral structures
  3. MCL complex

Associated osseous injury:

  • Fracture of radial head + coronoid process (= terrible triad); medial epicondyle fracture; Essex-Lopresti fracture (rare)

Forearm Fracture  !!navigator!!

Pediatric Distal Forearm Fracture

Buckle / Torus Fracture

= break in soft fibrous cortex with frequently intact periosteal sleeve

Cause: longitudinal compressive force

Location: distal radial + ulnar metaphyses

  • buckle in cortex on compression side of fracture
  • intact cortex on tension side

Prognosis: excellent stability; healing without complications after cast / splint immobilization

Greenstick Fracture

= break of bone cortex on tension side + intact periosteum

Cause: force perpendicular to long axis of bone

  • cortical disruption on tension (convex) side of fracture
  • intact cortex on compression side

Prognosis: unstable fracture → continued displacement for first 2 weeks

Barton Fracture

[John Rhea Barton (1794–1871), orthopedic surgeon at Pennsylvania Hospital, Philadelphia]

Mechanism: fall on outstretched hand

  • intraarticular oblique fracture of ventral / dorsal lip of distal radius
  • carpus dislocates with distal fragment up + back on radius

Chauffeur Fracture

= HUTCHINSON FRACTURE = BACKFIRE FRACTURE = LORRY DRIVER FRACTURE

[Jonathan Hutchinson (1828–1913), British surgeon]

= name derived from direct trauma to radial side of wrist sustained from recoil of crank used in era of hand cranking to start automobiles

Mechanism: acute dorsiflexion + abduction of hand

  • triangular fracture of radial styloid process

Colles Fracture

[Abraham Colles (1773–1843), surgeon in Dublin, Ireland]

= POUTEAU FRACTURE (term used in France)

[Claude Pouteau (1725–1775), surgeon in Lyon, France]

◊Most common fracture of forearm!

Mechanism: fall on outstretched hand

  • nonarticular radial fracture in distal 2 cm
  • dorsal displacement of distal fragment + volar angulation of fracture apex
  • ± ulnar styloid fracture
  • “silver-fork” deformity

Cx: posttraumatic arthritis

Rx: anatomic reduction important

Significant postreduction deformity:

  1. Residual positive ulnar variance >5 mm indicates unsatisfactory outcome in 40%
  2. Dorsal angulation of palmar tilt >15° decreases grip strength + endurance in >50%

Essex-Lopresti Fracture

[Peter Gordon Essex-Lopresti (1918–1951), surgeon at Birmingham Accident Center, England]

Mechanism: FOOSH-type injury

  • wrist pain / tenderness
  • “floating radius”:
    • comminuted displaced radial head fracture
    • dislocation of distal radioulnar joint = discrepancy of radioulnar distance >5 mm compared to contralateral uninjured wrist (on lateral radiograph)
  • disruption of interosseous membrane

Rx: nearly always surgical intervention

Galeazzi Fracture

[Ricardo Galeazzi (1866–1952), orthopedic surgeon in Italy]

= PIEDMONT FRACTURE

Mechanism: fall on outstretched hand with elbow flexed

  • radial shaft fracture (most commonly) at junction of distal to middle third with dorsal angulation
  • subluxation / dislocation of distal radioulnar joint
  • ulnar plus variance (= radial shortening) of >10 mm implies complete disruption of interosseous membrane = complete instability of radioulnar joint

Cx:

  1. High incidence of nonunion, delayed union, malunion (unstable fracture)
  2. Limitation of pronation / supination

Galeazzi-equivalent Fracture

= exclusively in skeletally immature children

Mechanism: hyperpronation / hypersupination

  • radial shaft fracture (4 primary types)
  • dislocation / epiphyseolysis of distal ulna

Monteggia-type Fracture

= ulnar shaft fracture + (often missed) radiocapitellar dislocation

Bado Classification:

[Jose Luis Bado (1903–1977), orthopedic surgeon in Uruguay]

Type I = classic Monteggia fracture

[Giovanni Battista Monteggia (1762–1815), professor of anatomy and surgery at Istituzioni Chirurgiche at University of Pavia]

Mechanism: direct blow to the forearm

  • anteriorly angulated proximal ulnar fracture
  • anterior dislocation of radial head
  • may have associated wrist injury

Cx: nonunion, limitation of motion at elbow, nerve abnormalities

Type II = reverse Monteggia fracture

  • radial head displaced posteriorly / posterolaterally
  • dorsally angulated proximal ulnar fracture

Type III

  • lateral dislocation of radial head
  • ulnar metaphyseal fracture

Type IV

  • anterior displacement of radial head
  • fracture of proximal third of radius + ulna at the same level

Smith Fracture

= REVERSE COLLES FRACTURE = REVERSE BARTON FRACTURE = GOYRAND FRACTURE (term used in France)

[Robert William Smith (1807–1873), succeeding Colles as professor of surgery at Trinity College in Dublin, Ireland]

Mechanism: hyperflexion with fall on back of hand

  • nonarticular distal radial fracture
  • ventral displacement of fragment
  • radial deviation of hand
  • “garden spade” deformity

Cx: altered function of carpus

Carpal Injury  !!navigator!!

Hamate Fracture

Prevalence: 1.7% of all carpal fractures

Mechanism: handle of racket / bat / club presses against protruding hook; axial loading force on body with clenched fist; fall on outstretched hand

May be associated with: perilunate dislocation

Location:

  1. hamate hook at palmar nonarticular surface
  2. body
  • grip weakness; pain with resistance to flexion of 5th finger
  • hamulus not depicted on standard PA view
  • cortical density of hamulus lower than normal

Cx: 5th finger flexor tendon rupture; ulnar nerve palsy; hook nonunion

DDx: os hamuli proprium (ovoid / pyramidal bone with peripheral cortical bone)

Rx: open reduction with internal fixation for fractures displaced >1 mm

Lunate Fracture

Prevalence: 4% of all carpal fractures

Mechanism: direct axial compression from head of capitate driven into lunate

Location: volar pole; dorsal pole; body

Fracture orientation: transverse, sagittal

Cx: nonunion → Kienböck disease

Pisiform Fracture

Prevalence: 1.3% of all carpal fractures (only 50% are diagnosed on PA radiograph)

Mechanism: fall on outstretched hand with direct impact on pisiform bone

May be associated with: carpal dislocation, distal radial fracture

Fracture type: linear, comminuted, chip

Cx: ulnar nerve injury

Rx: excision of pisiform bone

Scaphoid Fracture

= NAVICULAR FRACTURE

◊Most frequent (90%) of all carpal bones fractures!

Age: active men during 2nd + 3rd decade

Mechanism: fall on dorsiflexed outstretched hand (hyperextension injury)

Location: waist (80%) >proximal pole

Fracture orientation: horizontal oblique, vertical oblique, transverse

  • pain + tenderness at anatomic snuff box

Radiographic misses: 25–33–65%

N.B.: If initial radiograph negative, reexamine in 2 + 6 weeks after treatment with thumb-spica cast or proceed to CT / MRI!

CT: 89–97% sensitive; 85–100% specific; 97–99% NPV; 6–12 seconds examination time

MR: high sensitivity; 30–40 minutes examination time

Bone scan: up to 100% sensitive, 93% PPV after 2–3 days

Prognosis: dependent on following factors

  • fracture displacement with >1 mm offset / angulation / rotation of fragments (less favorable)
  • location of blood supply:
    • distal ⅓ (10%) = usually fragments reunite
    • middle ⅓ (70%) = failure to reunite in 30%
    • proximal ⅓ (20%) = failure to reunite in 90%
  • orientation of fracture
    • transverse / horizontal oblique = relatively stable
    • vertical oblique (less common) = unstable
  • Good prognosis with distal fracture + no displacement + no ligamentous injury!
  • Less favorable prognosis with displaced / comminuted fracture + proximal pole fracture!

Cx:

  1. Malunion; delayed union; nonunion (5–15%)
  2. Progressive fragment displacement
  3. Avascular necrosis of proximal fragment (13–50%); higher prevalence if proximal pole fractured ← distal location of main nutrient a.

Trapezium Fracture

Prevalence: 3–5% of all carpal fractures

Mechanism: direct blow to volar surface / avulsion

Location: trapezial ridge (= vertical prominence on volar aspect); body

Associated with: carpometacarpal joint involvement; fracture through base of 1st metacarpal / scaphoid

Triquetral Fracture

Prevalence: 18% of all carpal fractures

Mechanism: wrist hyperextension with ulnar deviation → impingement of ulnar styloid process against dorsal surface of triquetrum

Location:

  1. dorsal ridge fracture
  2. triquetral body fracture (in combination with perilunate dislocation)
  • fragment along dorsal edge of triquetrum (LAT view in slight pronation)

Hand Fracture  !!navigator!!

Bennett Fracture

[Edward Halloran Bennett (1837–1907), surgeon in Dublin, Ireland]

Mechanism: forced abduction of thumb

  • intraarticular fracture-dislocation of base of 1st metacarpal
  • small fragment of 1st metacarpal continues to articulate with trapezium
  • lateral retraction of 1st metacarpal shaft by abductor pollicis longus

Rx: anatomic reduction important, difficult to keep in anatomic alignment

Cx: pseudarthrosis

Boxer's Fracture

Mechanism: direct blow with clenched fist

  • transverse fracture of distal metacarpal (usually 5th)

Gamekeeper's Thumb

= SKIER'S THUMB (originally described as chronic lesion in hunters strangling rabbits)

Frequency: 6% of all skiing injuries; 50% of skiing injuries to the hand

Mechanism: violent abduction of thumb with injury to ulnar collateral ligament (UCL) in 1st MCP (faulty handling of ski pole)

  • disruption of ulnar collateral ligament of 1st MCP joint, usually occurring distally near insertion on proximal phalanx
  • avulsed bone fragment (in 12% of lesions)
  • radial stress examination results in abduction angle >35–45° or >10° greater than on opposite side
    • Controversial maneuver to document ligamentous disruption as it may complete incomplete tear
  • displacement of UCL superficial to aponeurosis of adductor pollicis (= Stener lesion) [torn end of UCL may be marked by avulsed bone fragment]

Rolando Fracture

[Silvio Rolando (?–1931?), surgeon in Genoa, Italy]

  • comminuted Y- / T-shaped intraarticular fracture-dislocation through base of thumb metacarpal

Prognosis: worse than Bennett fracture (difficult to reduce)

Chest Wall Fracture  !!navigator!!

Rib Fracture

◊Most common skeletal injury in blunt chest trauma (in 50%)

Associated with: pneumothorax, hemothorax, lung contusion / laceration

CT is the most sensitive technique for imaging rib fractures by determining the site and number of fractures and providing information about any associated injuries.

  • 1st–3rd rib
    ◊ Indicates high-energy trauma ← protected location
    Cause: acute trauma / fatigue fracture (from carrying a heavy back pack)
    Associated with: aortic / great vessel + subclavian vascular injury; brachial plexus injury; thoracic vertebral fracture; scapular fracture
  • Lower ribs
    Associated with: injury to liver, spleen, kidney, diaphragm

Cx: atelectasis + subsequent pneumonia ← limited respiratory movement

Flail Chest

= segmental fracture of >3 contiguous ribs in >2 places

In >50% associated with: significant intrathoracic injury that requires surgical Rx

  • paradoxic motion of fractured chest wall with respiration on clinical examination
  • respiratory failure

Rx: mechanical ventilation for prolonged periods

Cough Fracture

Location: 4th–9th rib in anterior axillary line

Scapula Fracture

Prevalence: 3–5% of all shoulder girdle fractures

  • In 3.7% of patients with multiple injuries

Cause: motor vehicle accident, fall from great height

Associated with: pneumothorax, hemothorax, lung injury, spinal injury (in 35–98%)

Prognosis: displaced glenoid intraarticular fracture + displaced juxtaarticular fracture require surgical management

Sternal Fracture

Cause: deceleration, direct blow

Associated with: anterior mediastinal hemorrhage

Sternal fractures are best demonstrated on multiplanar reformatted CT images, especially on sagittal views.

Pelvic Fracture  !!navigator!!

Unstable pelvic fractures:

  1. anterior compression
    1. Bilateral vertical pubic rami fractures
    2. Symphysis + sacroiliac joint diastasis
  2. lateral compression
    1. Malgaigne (ipsilateral anterior + posterior fx)
    2. Bucket-handle (contralateral anterior + posterior fx)
  3. vertical shear
    1. Superior displacement of pelvis

Acetabular Fracture

Anatomy & Function:

most important portion of acetabulum is roof / dome; weight-bearing surface for entire lower limb is derived + supported by 2 columns which are oriented in an inverted “Y” and join above the acetabular roof at an angle of 60°:

  1. anterior iliopubic column of acetabulum
  2. posterior ilioischial column of acetabulum

Classification (Judet and Letournel):

  1. Elementary 5 fractures
    Posterior wall* 27% Anterior column 5%
    Transverse* 9% Posterior column 4%
    Anterior wall 2%
  2. Associated 5 fractures (= combinations / partial combinations of elementary fractures)
    Transverse + posterior wall* 27%
    Both columns* 19%
    T-shaped* 6%
    Anterior wall + posterior hemitransverse 5%
    Posterior column + posterior wall 3%

*= account for 80%of all acetabular fractures (3 most common types underlined)

Posterior wall (lip / rim) fracture (27%)

Mechanism: indirect force transmitted through length of femur with flexed hip joint (knee strikes dashboard)

Associated with: posterior dislocation of femur

A posterior wall fracture involves only the posterior articular surface and is not seen on the medial acetabular surface.

Transverse fracture (9%)

N.B.: most difficult to diagnose + comprehend

  • transects both the iliopubic + ilioischial columns with fracture line in an anteroposterior direction

On subsequent axial CT images, a transverse acetabular fracture is represented by a sagittal fracture line simulating anterior and posterior wall fractures, a pitfall easily avoided with 3-D reconstructions.

Anterior column fracture (5%)

Mechanism: blow to greater trochanter with hip externally rotated

Associated with: posterior column / transverse fracture

  • fracture begins between anterior iliac spines + traverses the acetabular fossa + ends in the ischiopubic ramus

Posterior column fracture (4%)

Mechanism: indirect force transmitted through length of femur with hip abducted

Associated with: posterior dislocation of femur + sciatic nerve injury

  • fracture begins at greater sciatic notch + traverses the posterior aspect of acetabular fossa + ends in the ischiopubic ramus

Anterior wall fracture (2%)

Mechanism: force transmitted through greater trochanter

Associated with: posterior dislocation of femur + sciatic nerve injury

  • fracture begins on anterior rim of acetabulum + emerges on lateral aspect of superior pubic ramus

Associated Both Column fracture (19%)

= separation of both columns from each other with 2 dominant fractures nearly perpendicular to each other

Associated with: additional fracture lines + medial displacement of femoral head

  • “spur sign” = shard of bone superior to femoral neck (on obturator view)

With both-column fractures the entire weight-bearing portion of the acetabulum is disconnected from the sciatic buttress.

Bucket Handle Fracture

  • double vertical fracture through superior and inferior pubic rami + sacroiliac joint dislocation on contralateral side

Duverney Fracture

[Joseph Guichard Duverney (1648–1730), French surgeon]

  • isolated fracture of iliac wing

Malgaigne Fracture

[Joseph François Malgaigne (1806–1865), French surgical historian, published first comprehensive book on fractures]

= fracture-dislocation of one side of the pelvis with anterior + posterior disruption of pelvic ring

Mechanism: direct trauma

  • shortening of involved extremity
  • vertical fractures through one side of pelvic ring
    1. superior to acetabulum (ilium)
    2. inferior to acetabulum (pubic rami)
    3. ± sacroiliac dislocation / fracture
  • lateral unstable fragment contains acetabulum

Proximal Femur Fracture  !!navigator!!

Intracapsular Femur Fracture

  1. Complete Femoral Head Fracture (uncommon)
    Often associated with: posterior hip dislocation
    Pipkin classification:
    • Type 1 below fovea centralis
    • Type 2 above fovea centralis with ligamentum teres often attached to fracture fragment
    • Type 3 type 1/2 + femoral neck fracture
    • Type 4 type 1/2 + acetabular fracture

    The lateral margin of the femoral head-neck junction is crucial as it is the most common penetration point of the lateral epiphyseal vessels. Fractures involving this area create a high risk of critical vascular injury resulting in nonunion / AVN, with decreasing risk as fractures occur more distally along the femoral neck.
  2. Osteochondral Impaction Fracture of Femoral Head
    Often associated with: anterior hip dislocation
    • radiographically relatively occult:
      • subtle flattening / focal compression defect of head
    • subchondral fracture line + marrow edema at MRI
  3. Femoral Neck Fracture
    Location: subcapital, transcervical, basicervical
    • valgus-impacted / nondisplaced
      N.B.: frequently missed on initial radiographs ← subtlety of cortical distortion at femoral head-neck junction + only mild fracture angulation
    • varus-impacted (“mushroom cap” = medially rotated head) / displaced → high risk for AVN
  4. Femoral Neck Stress Fracture
    • often initially radiographically occult
    • Inferomedial cortex = fatigue fracture
      Age: young athletic patient
      • cortical thickening + incomplete fracture line
      • extensive marrow edema
    • Superolateral cortex = insufficiency / fatigue fracture
      Age: osteoporotic elderly
      • frequently displaced ← side of high tension

Extracapsular Fracture

  1. Intertrochanteric Fracture
    Cause: frequently osteoporosis in the elderly woman
    N.B.: Isolated fractures of the lesser trochanter in adults should be considered PATHOGNOMONIC for tumor infiltration.
  2. Subtrochanteric Fracture
    • comminuted / spiral morphology

Knee Fracture  !!navigator!!

Anterior Cruciate Ligament Avulsion Fracture

Age: children >adults

Mechanism:

  1. children: forced flexion of knee + internal rotation
  2. adults: severe hyperextension

May be associated with: kissing bone contusion + tear of medial collateral lig. + PCL

  • aching flexed knee; signs of anterior instability
  • avulsion of ACL from its distal insertion site just medial and anterior to tibial eminence

Arcuate Complex Avulsion Fracture

Mechanism: direct blow to anteromedial tibia with knee in extension / varus force to externally rotated tibia / sudden hyperextension

May be associated with:

  • disruption of ACL and PCL, lateral capsular lig., iliotibial band, popliteal muscle, menisci, damage to peroneal nerve
  • subtle physical finding
  • mild swelling + tenderness
  • “arcuate” sign = avulsed elliptic bone fragment at fibular styloid process with its long axis horizontally oriented (AP view)
  • bone marrow edema in head of fibula + adjacent soft-tissue swelling

Biceps Femoris Tendon Avulsion Fracture

May be associated with:

  • disruption of lateral collateral lig., Segond fracture, damage to popliteal musculotendinous unit
  • irregular bone fragment off lateral fibular head in posterolateral aspect of knee joint (DDx: “arcuate sign” = horizontally oriented elliptic fragment off fibular styloid process)
  • avulsion + retraction of biceps femoris tendon

Iliotibial Band Avulsion Fracture

= primary stabilizing structure of anterolateral knee

Mechanism: pure varus force (rare)

May be associated with: ACL injury

  • avulsion + retraction of iliotibial band from its distal insertion on Gerdy tubercle

Posterior Cruciate Ligament Avulsion Fracture

Location: at tibial insertion site (40–55%)

Mechanism: direct blow to anterior tibia with flexed knee (dashboard injury); severe hyperextension

May be associated with:

  • disruption of medial / lateral collateral ligament complexes; medial / lateral meniscal tear; bone contusion of anterior tibia + lateral femoral condyle
  • focal discontinuity of posterior articular surface (LAT view)

Quadriceps Tendon Avulsion Fracture

Cause: strong deceleration in young athletes

Mechanism: sudden contraction of quadriceps muscle during jumping / kicking

  • comminuted bone fragments off superior aspect of patella (LAT view)
  • patella baja deformity = abnormally low position of patella with respect to femur
  • marrow edema in upper pole of patella
  • suprapatellar joint effusion

DDx: rupture of quadriceps tendon (at musculotendinous junction; repetitive microtrauma / systemic diseases like HPT, diabetes, collagen vascular disease, gout)

Reverse Segond Fracture

= cortical avulsion of tibial insertion of deep capsular component of medial collateral ligament

Mechanism: external rotation + valgus stress

May be associated with:

  • midsubstance tear of posterior cruciate ligament; avulsion of PCL from posterior tibial plateau; tear of medial meniscus
  • elliptic bone fragment arising from medial aspect of proximal tibia

Segond Fracture

[Paul Ferdinand Segond (1851–1912), surgeon in chief at Salpêtrière in Paris, France]

= cortical avulsion of the tibial insertion of middle third of lateral capsular ligament ± avulsion of iliotibial tract ± anterior oblique band

Mechanism: internal rotation + varus stress

May be associated with:

  • lesion of anterior cruciate ligament (75–100%), meniscal tear (67%), avulsion of fibular attachment of long head of biceps femoris tendon + fibular collateral ligament
  • pain at lateral joint line
  • anterolateral rotational instability of the knee
  • “lateral capsular” sign = small elliptic fragment of proximal lateral tibial rim just distal to lateral plateau parallel to tibia (AP view)
  • marrow edema on MRI

Semimembranosus Tendon Avulsion Fracture

Mechanism: external rotation + abduction of flexed knee; varus force applied to flexed knee; valgus force applied to tibia

May be associated with:

  • ACL tear; tear of posterior horn of medial meniscus; posterior meniscocapsular separation
  • tiny avulsed bone fragment off tibia displaced posterosuperiorly (difficult to see on LAT view)

Tibial Plateau Fracture (Schatzker classification)

Type I = wedge-shaped pure cleavage fracture 6%

  • <4 mm depression / displacement
  • ± distraction injury to MCL / ACL

Type II = combined cleavage + lateral plateau compression fracture 25%

  • distraction injury of MCL / medial meniscus in 20%

Type III = pure compression fracture of lateral tibial plateau 36%

  • depression of articular surface:
    • lateral depression (type IIIA)
    • central depression (type IIIB)

Type IV = medial plateau fracture with a split / depressed comminution 10%

  • ± distraction injury of lateral knee with LCL tear / posterolateral corner injury
  • ± fracture / dislocation of proximal fibula
    Cx: injury to peroneal nerve / popliteal vessels

Type V = wedge fracture of medial + lateral plateau in 3%

  • often inverted Y appearance
  • articular depression typically of lateral tibial plateau
  • ± fracture of intercondylar eminence (= unstable 4-part fracture)
  • peripheral meniscal detachment (50%)
  • ACL avulsion injury (33%)

Type VI = transverse / oblique fracture with dissociation of metaphysis from diaphysis 20%

  • open fracture in (33%)

◊Lateral plateau fractures (type I–III) are most common!

◊Fractures of medial plateau are associated with greater violence and higher percentage of associated injuries!

Mechanism:

  1. for type I + II + III = valgus force combined with axial loading (“bumper / fender fracture” from lateral force of automobile against a pedestrian's fixed knee) / compression force often on extended knee
  2. for type IV = varus force combined with axial loading on hyperflexed knee
  3. type V + VI = combination of valgus + varus stresses combined with axial loading

Tibial Tubercle Fracture

Ogden classification:

  • Type 1: involvement of distal portion of tubercle
  • 1A: without displacement
  • 2A: with displacement
  • Type 2: involvement of entire ossification center
  • 2A: separation of tubercle from proximal tibia
  • 2B: comminuted fracture
  • Type 3: involvement of proximal tibial epiphysis into joint space
  • 3A: without displacement
  • 3B: with displacement

Toddler's Fracture  !!navigator!!

= CHILDHOOD ACCIDENTAL SPIRAL TIBIAL FRACTURE (CAST)

= lower extremity fracture associated with onset of ambulation

Cause: low-energy trauma ± rotational component

Age: toddler (9 months–3 years), young child (<8 years)

  • refusal to bear weight without recognized trauma

Location: distal third to distal half of tibia; fibula, tarsus (posterior calcaneus >base of cuboid >talus)

  • (typically) nondisplaced oblique spiral fracture of distal tibia
  • undisplaced spiral fracture

Foot Fracture  !!navigator!!

Ankle Fracture

Frequency: ankle injuries account for 10% of all emergency room visits; 85% of all ankle sprains involve lateral ligaments

Lateral Malleolar Fractures

Weber Type A

[Bernhard Georg Weber (1929–), orthopedic surgeon in St. Gall, Switzerland]

= SUPINATION-ADDUCTION INJURY = INVERSION-ADDUCTION INJURY

Mechanism:

  1. avulsive forces affect lateral ankle structures
  2. impactive forces ← talar shift stresses medial structures
  • sprain / rupture of lateral collateral ligament
    • Anterior tibiofibular ligament ruptures alone in 66%
    • Injury of all 3 lateral ligaments in 20%

Prognosis: chronic lateral ankle instability in 10–20%

  • transverse avulsion of malleolus sparing tibiofibular ligaments
  • ± oblique fracture of medial malleolus
  • ± posterior tibial lip fracture

Weber Type B

= SUPINATION-ABDUCTION INJURY = EVERSION-EXTERNAL ROTATION

Mechanism:

  1. avulsive forces on medial structures
  2. impacting forces on lateral structures (talar impact)
  • oblique / spiral fracture of lateral malleolus starting at level of joint space extending proximally
  • lateral subluxation of talus
  • partial disruption of tibiofibular ligament
  • ± sprain / rupture / avulsion of deltoid ligament
  • ± transverse fracture of medial malleolus
  1. Dupuytren Fracture
    [Guillaume Dupuytren (1777–1835), French surgeon]
    • fracture of distal fibula above a disrupted tibiofibular ligament + disruption of deltoid lig.
  2. Le Fort Fracture of Ankle
    [Léon Clément Le Fort (1829–1893), French surgeon]
    • vertical fracture of anterior medial portion of distal fibula
    • avulsion of anterior tibiofibular ligament

Weber Type C

= PRONATION-EXTERNAL ROTATION = EVERSION + EXTERNAL ROTATION

  • fibular fracture higher than ankle joint (Maisonneuve fracture if around knee)
  • ± deltoid ligament tear
  • ± medial malleolar fracture
  • tear of tibiofibular ligament / avulsion of anterior tubercle (Tillaux-Chaput) / avulsion of posterior tubercle (Volkmann)
  • tear of interosseous membrane = lateral instability
  1. Tillaux Fracture
    [Paul Jules Tillaux (1834–1904), French surgeon and anatomist]
    • avulsion injury of anterior tibial tubercle at attachment of distal anterior tibiofibular ligament
    • type 3 epiphyseal plate injury in children
    • CT more sensitive in identification of fracture displacement >2 mm (cutoff that requires reduction)

  2. Maisonneuve Fracture
    [Jacques Gilles Maisonneuve (1809–1897), student of Dupuytren]
    • tear of distal tibiofibular syndesmosis + interosseous membrane
    • spiral fracture of upper third of fibula
    • associated fracture of medial malleolus / rupture of deep deltoid ligament

Calcaneal Fracture

Frequency: most commonly fractured tarsal bone; 60% of all tarsal fractures; 2% of all fractures in the body; commonly bilateral

Mechanism: fall from heights (axial overload)

In 10% associated with: thoracolumbar compression fracture

Age: 95% in adults, 5% in children

  • adulthood: intraarticular (75%), extraarticular (25%)
  • childhood: extraarticular (63–92%)

Classification:

  1. extraarticular fracture (25%) = no involvement of posterior talar facet:
    • anterior process fracture
    • fracture of mid calcaneus (body, sustentaculum tali, peroneal tubercle, lateral calcaneal process)
    • fracture of posterior calcaneus (tuberosity, medial calcaneal tubercle)
  2. intraarticular fracture (75%)
    • subtalar joint involvement: undisplaced, displaced, comminuted
    • calcaneocuboid joint involvement

Sanders Classification of intraarticular fractures (correlates with prognosis):

Technique: CT with image reformation parallel + per-pendicular to posterior facet of subtalar joint

  • Type I nondisplaced (<2 mm) fracture
  • Type II 2 articular fragments
  • Type IIA laterally located fracture line
  • Type IIB centrally located fracture line
  • Type IIC medially located fracture line
  • Type III 3 articular fragments
  • Type IIIAB lateral+ central fracture line
  • Type IIIAC lateral + medial fracture line
  • Type IIIBC central + medial fracture line
  • Type IV >3 intraarticular fracture lines
  • apex of lateral talar process does not point to “crucial angle” of Gissane
  • Böhler angle decreased below 28°–40°

Chopart Fracture

[François Chopart (1743–1795), surgeon in Paris, France]

  • fracture-dislocation through midtarsal / Chopart (calcaneocuboid + talonavicular) joint
  • commonly associated with fractures of the bones abutting the joint

Jones Fracture

[Robert Jones (1857–1933), British orthopedic surgeon and pioneer in radiology described fracture in Ann Surg 1902]

Mechanism: adduction of forefoot with ankle in plantar flexion

  • transverse fracture at base of 5th metatarsal bone at junction of diaphysis and metaphysis (>1.5 cm distal to proximal tip of metatarsal tuberosity)

Cx: delayed union / nonunion (poor blood supply)

Lisfranc Fracture

[Jacques Lisfranc de Saint Martin (1787–1847), field surgeon in Napoleon's army]

Mechanism: metatarsal heads fixed and hindfoot forced plantarward and into rotation

  • fracture-dislocation / fracture-subluxation of tarsometatarsal joints (typically 2 through 5)
  • lateral displacement of metatarsals

Peroneus Brevis Avulsion Fracture

= METATARSAL 5 TUBEROSITY FRACTURE

◊Most common fracture of the proximal 5th metatarsal bone

Mechanism: plantar flexion + inversion (stepping off a curb)

  • transverse avulsion fracture of base of 5th metatarsal bone

Location: proximal to metatarsal tuberosity (insertion of peroneus brevis tendon); usually extraarticular

DDx: Jones fracture (slightly different location)

Shepherd Fracture

[Francis J. Shepherd (1851–1929), demonstrator in anatomy at McGill University in Montreal, Canada]

  • fracture of lateral tubercle of posterior process of talus

DDx: os trigonum

 Outline