MSK Flashcards
Ddx pathologic fracture - benign tumour
Aneurysmal bone cyst
Enchondroma
Eosinophilic granuloma
Fibrous dysplasia
Giant cell tumour
Nonossifying fibroma
Ostochondroma
Unicameral bone cyst
Ddx pathological fracture - malignant tumour
Chondrosarcoma
Ewing sarcoma
Neuroblastoma
Osteogenic sarcoma
Ddx pathological fracture - Hereditary diseases
Gaucher disease
Neurofibromatosis
Osteogenesis imperfecta
Osteopetrosis
Sickle cell disease
Ddx Pathologic fracture - metabolic disorders
Copper deficiency
Cushing syndrome
Hyperparathyroidism
Renal osteodystrophy
Rickets
Scurvy
What pathogens are most commonly responsible for septic arthritis?
** S. aureus
S. pneumoniae
GAS
Gonococcus (older)
Kingella kingae
Salmonella - kids with hemoglobinopathiesq
How is septic arthritis spread?
hematogenous usually
What is the imaging of choice for SCFE?
AP + frog-leg radiographs
MRI works too
What endocrinopathy is associated with SCFE outside the normal age range?
hypothyroidism
what is the most common hip disorder in adolescent patients?
SCFE
How much more common is SCFE in males than females?
2x more common
In what directio is slippage most common in SCFE?
posterior + inferior relative to the proximal femoral metaphysis
What is the cutoff between acute and chronic scfe?
3 weeks
What are risk factors for “atypical” SCFE?
endocrine disorder (esp hypothyroid)
renal failure
radiation therapy
What hip movements are limited/painful in SCFE?
full flexion’
internal rotation
abduction
What are the cardinal signs of tenosynovitis?
four cardinal Kanavel signs
- finger held in mild flexion
- fusiform swelling of the digit
- tenderness along the entire tendon sheath, especially at the palmar surface of the metacarpophalangeal (MCP) joint
- severe pain with passive extension
What is the maximum angulation acceptable for a fracture of the 4th or 5th metacarpals?
Up to 40 degrees is acceptable for the 4th and 5th metacarpals
What is the maximum angulation acceptable for a fracture of the 2nd or 3rd metacarpals?
10 to 20 degrees is acceptable for the 2nd and 3rd metacarpals
What are the signs and symptoms of compartment syndrome?
7 Ps
- pulseless
- pale
- paralysis
- hard on palpation
- painful
- poikilothermia
- paresthesia
What is the most common site of compartment syndrome?
anterior compartment of the leg
When does muscle necrosis become irreversible after start of tissue anoxia??
6-8 hrs
What causes the Volkmann’s contracture?
Displaced supracondylar fractures may injure the anterior interosseous artery and the flexor compartment of the forearm causing a compartment syndrome
What nerve is usually affected in compartment syndrome of the flexor aspect of the forearm?
Median nerve
how to test for axillary nerve damage?
o innervates deltoid and teres minor (motor) = abduction and external rotation
o sensation = lateral shoulder sensation
What are the classic findings on X-ray of a lisfranc fracture?
Widened space (diastasis) between base of 1st & 2nd metatarsals
Fleck fracture adjacent to base of 1st MT
Loss of alignment of medial edge of proximal second MT with medial edge of second cuneiform
What is the classic mechanism of injury for a lisfranc fracture?
Axial load on plantar flexed foot
What are reasons to non urgently send patient to ortho for consult in MT fractures?
Displaced fracture of fifth metatarsal styloïde
Shaft fracture near metatarsal head
Unacceptable position needing reduction or unsuccessful reduction attempts
Lisfranc injury or suspected
Multiple Mt fractures
What is a jones fracture?
Fracture at the diaphyseal-metaphyseal junction at base of 5th MT
4 signs of SCFE on X-ray
Klein line (along superior edge of neck of femur) does not intersect epiphysis (AP view)
Widened epiphysis
Caudal displacement of femoral head
Posterior displacement of the epiphysis
A line along the inferior margin of the proximal femur should smoothly continue over the physis and epiphysis in an S shape. If there is discontinuity or abrupt bending of the line, SCFE should be strongly suspected
What endocrinopathy is most commonly associated with SCFE?
hypothyroidism
In what percentage of cases are SCFE bilateral?
25%
What are signs of SCFE on physical exam?
limited internal rotation
pain with external rotation
What is the difference between a SH1 fracture and a SCFE?
in SCFE the perichondrium remains intact
Risk factors for SCFE
pre-pubertal/around puberty
M>F
African american
Obesity
Vertically inclined physeal angles
Hypothyroidism
Renal failure
Radiation therapy
What is the time period for chronic vs acute SCFE?
Chronic > 3 weeks
Where does the chin point in a muscular torticollis?
chin points toward unaffected side
What pressure is diagnostic of compartment syndrome?
30mmHg
What is rotatory subluxation?
consider if head cannot be rotated past midline
spontaneous or follows URTI or traumatic event
Chin points to same side as SCM spasm (cock-robin position)
What xray finding could be indicative of rotary subluxation?
open-mouth radiograph with one of lateral masses of C1 appearing more forward and closer to midline vs other mass appears narrow and away from midline
*CT scan is more useful
Possible traumatic causes of torticollis
cervical fracture
atlanto-axial subluxation
muscle spasm
rotary dislocation
SAH with extension into neck
Non-traumatic causes of torticollis
Spinal column infection (discitis, osteomyelitis, epidural abscess)
RPA
Cervical adenitis
Myositis of SCM
Rotary dislocation (Grisel’s syndrome)
Complications of splinting of an MSK injury
Neurovascular compromise
Pressure ulcers
Contact dermatitis
Contracture if prolonged splint or not in position of function
Volkmann’s Contracture
Ischemic contracture resulting from unrecognized vascular compromise due to a supracondylar fracture, vessel injury during reduction or compartment syndrome - anterior interosseous artery
Most common pathogens of diskitis and vertebral osteomyelitis
Staph
GAS
E.Coli
Kingella kingae (< 3 years)
What is the clinical appearance of a volkmann’s contracture?
Decreased sensation
Paleness of the skin
Muscle weakness and loss (atrophy)
Deformity of the wrist, hand, and fingers that causes the hand to have a claw-like appearance
Contraindications to knee aspiration
No absolute contraindications. Relative contraindications include:
-overlying cellulitis
- coagulopathy/bleeding disorders
- a joint prosthesis
- acute fracture
- adjacent osteomyelitis
- uncooperative patient.
What is a Jefferson fracture
bursting fracture of ring of C1
result of axial load
radiographic criterion for Jefferson fracture
lateral offset of lateral mass of C1 more than 1mm from vertebral body of C2
In what age grops can a “pseudo-jefferson fracture” be seen?
0-6 yrs
What is a hangman’s fracture
traumatic spondylolisthesis of C2 resulting from hyperextension
sublixation associated with hangman’s fracture
anterior subluxation C2 on C3
How can the distinction be made between a subtle hangman’s fracture and pseudosubluxation
using Swischuk’s posterior cervical line - > 1.5-2mm suggests occult fracture
Causes of ligament instability that can lead to atlantoaxial subluxation
tonsillitis
cervical adenitis
pharyngitis
arthritis
connective tissue disorders
T21
Radiographic findings suggestive of atlantoaxial subluxation
widened predental space on lateral radiograph
4 types of atlantoaxial subluxation
Type 1 - no displacement of c1
Type 2 - 3-5mm C1 on C2 anterior displacement
Type 3 - >5 mm C1 on C2 anterior displacement
Type 4 - posterior displacement of C1 on C2
what is the most common cause of atlantoaxial subluxation in young children?
dens fracture
Cause of cervical distraction injures
rapid acceleration or deceleration incidents
eg. MVC, pedestrian accident, infant abusive head trauma
Measurements for potential distraction injuries of cervical spine
atlantooccipital distance should not exceed 5mm
C1-C2 interspinous distance should not exceed 10mm
What is sun’s ratio
C1-C2:C2-C3
should be < 2.5 - if more, suggests potential ligamentous instability
most frequent cause of vertebral compression injuries
axial loading and hyperflexion
radiographic findings of vertebral compression injuries
isolated anterior wedging, teardrop fracture, burst vertebral bodies
What is SCIWORA?
spinal cord injury without radiographic abnormality
mainly children < 8 y
symptoms consistent with cervical cord injuries but no abnormal radiographs
How to distinguish between muscular torticollis vs SCM spasm
muscular = chin points toward unaffected side
SCM - chin points toward affected side
when should rotary subluxation be considered in a patient with torticollis
when patients head cannot be rotated past midline
chin pointed towards same side as SCM spasm
radiographic findings of rotary subluxation
openmouth radiograph - one of lateral C1 masses appears forward and lcoser to midline while opposite lateral mass appears narrow and away from midline
(lateral offset)
MOst useful diagnostic tool in rotary subluxation
CT scan
treatment of mild rotary subluxation
cervical collar
analgesia
What is anterior cord syndrome
loss of neurologic function in areas supplied by anterior spinal artery with loss of motor function below level of the lesion but normal touch and proprioceptive function
What is posterior cord syndrome?
loss of proprioceptive function,. deep pressure, pain, vibratory sense with preservation of temperature sensation and motor function
What is Brown-Sequard syndrome?
hemisection of the cord
contralateral loss of pain and temperature sensation with ipsilateral motor findings below the lesion
What is central cord syndrome
injury most severe in center of the cord
motor strength more severely depressed in arms than legs
Which lesions of the spinal cord are usually non-reversible?
anterior cord syndrome
complete transection
What type of thoraco-lumbar spinal fracture requires immediate surgical consult?
any chance or burst fracture associated with 15+ degrees of kyphosis or any degree of neurologic impairment
