Sports Medicine: Just the Facts

RADIOGRAPHIC LINES AND ANGLES IN SPORTS MEDICINE 611

•Acromioclavicular separation

• Osteolysis of the distal clavicle

CORACOCLAVICULARDISTANCE(CCD)

• Normal: 1.0–1.3 cm


• Greater than 1.3 cm considers Grade II or higher
  acromioclavicular separation.
  
  
  • Grade I: CCD =1.0–1.3 cm
  
  
  • Grade II: CCD =1.0–1.5 cm
  
  
  • Grade III: CCD ≥1.5 cm
  
  
  
  

ANGLEBETWEENHUMERALHEAD
ANDHUMERALSHAFT

• The angle formed between a line bisecting the shaft of
  the humerus and a line bisecting the head of the
  humerus.
  
  
  • Normal = 135 °
  
  
  • An angle ≤ 90 °or >180°signifies a fracture that may
    require surgical reduction.
  
  
  
  

DISTAL HUMERUS, ELBOW, AND PROXIMAL
FOREARM

BAUMANN’SANGLE

• AP elbow


• Used to evaluate suspected elbow fractures in skele-
  tally immature patients.


• The angle of the distal lateral humeral condylar physis
  relative to the metaphysis.


• Normal: 8–20°


• An absolute number degree is not as significant as dif-
  ference from the contralateral side.

CARRYINGANGLE

• AP elbow


• Longitudinal axis of humerus to forearm.


• Normal: 15°children <4-year-old; 17.8°adults


• No significant difference between males and females.

HUMERAL-LATERALCONDYLARANGLE

• Lateral view of elbow.


• Longitudinal axis of humerus relative to axis of lateral
  condyle.


• Normal: Symmetric, 40°


• If abnormal, consider supercondylar fracture.

ANTERIORHUMERALLINE

• Lateral view of elbow.


• Line down anterior humerus through lateral condyle.


• Normal: Line should pass through middle third of lat-
  eral condyle ossification nucleus.


• If abnormal, suspect supracondylar fracture.

ANTERIORFATPAD

• Lateral elbow radiograph.


• Normally a thin radiolucent line over the coronoid fossa.
  
  
  • If displaced anteriorly from the fossa, suspect capsular
    distention secondary to a fracture causing a hemarthro-
    sis.
  
  
  
  

POSTERIORFATPAD

• Lateral elbow radiograph.
  •Over olecranon fossa.


• If seen, considered diagnostic of an intra-articular
  elbow fracture.


• Only seen with significant hemarthrosis of the joint.

RADIOCAPITELLARLINE

• Lateral elbow radiograph.
  •A line drawn bisecting the long axis of the radius and
  head of the radius should intersect the capitellum
  regardless of the degree of elbow flexion or extension.


• If it does not, suspect fracture of proximal radius or
  distal humerus.

HAND AND WRIST

LATERAL WRIST RADIOGRAPHS

RADIALAXIS

• Longitudinal axis of radius.


• Runs through the center of the medullary canal at 2
  and 5 cm proximal to the radiocarpal joint.

LUNATEAXIS

• Bisector of lunate.


• Runs perpendicular to the tangent of the two distal
  poles.

CAPITATEAXIS

• Longitudinal axis of capitate.


• Bisects the proximal and distal poles.

GENERALRULES OF THERADIAL, LUNATE,

ANDCAPITATEAXES

• All three should form one line on the lateral wrist view.


• If the lunate is subluxed:
  
  
  • Line of axes of radius and capitate will not bisect the
    lunate.
  
  
  • The radial and capitate axes will transect only a
    small portion or none of the lunate.
    •With extension, capitate and lunate should both
    extend relative to radial axis.
    •With flexion, capitate and lunate should both flex rel-
    ative to radial axis.
    •Asynchronous movement with flexion or extension sug-
    gests carpal instability.
  
  
  
  

SCAPHOIDAXIS

• Bisector of the scaphoid.


• Bisects proximal and distal poles.