Sports Medicine: Just the Facts

SPACEAVAILABLE FORCORD(SAC)
•Also known as spinal canal width.

• Posterior aspect of odontoid process or vertebral body
  to the nearest posterior structure.


• Normal @ craniocervical junction: 13–14 mm


• Normal below C2: 12 mm


• Significance: Cord compression

ATLANTALDENSINTERVAL(ADI)

• Distance from anterior border of odontoid to posterior
  border of atlantal ring.


• Normal: <3 mm (adults); <4 mm (children)


• Significance: Atlantoaxial instability


• ADI 10–12 mm: All ligaments ruptured

THORACIC AND LUMBAR SPINE

COBBANGLE
•Degree of scoliotic curvature on anteroposteior(AP)
radiograph.

• Select vertebrae most tilted from horizontal above and
  below apex of curve.


• Line drawn along superior surface of upper vertebra
  and along lower surface of lower vertebra.
  •Method 1
  
  
  • Perpendiculars are drawn to each line.
  
  
  • Where perpendiculars intersect: Cobb angle
    •Method 2
    •Where lines drawn along superior surface of upper
    vertebra and along lower surface of lower vertebra
    intersect.
  
  
  
  


• Both methods produce equivalent angles.


• Normal = 0o


• Can use same method to measure kyphosisand lordo-
  sison lateral films.

CENTRALSACRALLINE

• Drawn through center of sacrum and perpendicular to
  line connecting the tops of the iliac crests.
  •Patient must be standing and pelvis level.


• Normal: Line passes through each vertebrae up the
  spine.
  •Vertebrae bisected by this line in scoliosis patients are
  considered stable (surgery).

HARRINGTONSTABLE-ZONELINES
•Parallel lines through lumbrosacral facets
•Normal: All vertebrae fall between these lines.
•Vertebrae within this zone are stable (surgery for rod
placement).

SCOTTYDOG

• Used for diagnosis of spondylolysis on oblique views
  of the lumbar spine.
  
  
  • The neck of the “Scotty Dog” appears to have a collar
    on it.
  
  
  • Signifies fracture of the pars interarticularis.
  
  
  
  

SACRALINCLINATION

• Relationship of sacrum to the vertical plane.


• Method of measuring the lumbosacral kyphosis in
  patients with higher degrees of spondylolisthesis.

SLIPANGLE

• Angle between intersection of lines drawn along pos-
  terior border of S1 and the inferior endplate of L5.


• Method of measuring the lumbosacral kyphosis in
  patients with higher degrees of spondylolisthesis.


• Used in evaluating and describing L5–S1 spondylolis-
  thesis.


• Normal < 0 °.


• Greater than 45°has a higher risk of slip progression.

PERCENTAGESLIP

• Percentage of anterior displacement of the superior
  vertebra on the lower body.


• Used in evaluating, describing, and grading spondy-
  lolisthesis.


• Grade I slip: 0–25% displaced


• Grade II slip: 25–50% displaced


• Grade III slip: 51–75% displaced


• Grade IV slip: 76–100% displaced


• Grade V slip: >100% displaced

SHOULDER, CLAVICLE, PROXIMAL HUMERUS

ACROMIALTYPE

• Useful in the evaluation of rotator cuff impingement.


• Describes morphology of acromium as viewed on
  outlet view of plain radiographs or T1 coronal oblique
  view of magnetic resonance imaging(MRI) as depicted
  above.
  •Type 1: Flat
  •Type 2: Curved
  •Type 3: Hooked

ACROMIOHUMERALINTERVAL

• AP shoulder with humerus in neutral rotation.


• The minimum distance between inferior surface of the
  acromion and the articular cortex of the humerus.


• Normal: 7–11 mm


• Greater than 7 mm thought to be at risk for impinge-
  ment of the rotator cuff tendons and an indicator of a
  possible rotator cuff tear.

WIDTH OFACROMIOCLAVICULARJOINTSPACE

• Normal: 0.3–0.8 mm


• If >0.8 mm, consider the following:

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