Anatomical relation and carpal instability

1. ANATOMICAL RELATION AND CARPAL INSTABILITY
DR SHARAN HONGAL

2. ANATOMY

4.  Radial height: the distance between two parallel lines drawn perpendicular to the long axis of the
radial shaft— one from the tip of the radial styloid and the other from the ulnar corner of the lunate
fossa. Average = 12 mm.

6.  Radial inclination: the angle between two lines—one drawn perpendicular to the long axis of the
radius at the ulnar corner of the lunate fossa and the other between that point in the lunate fossa and
the tip of the radial styloid. Average = 23°.

8.  Ulnar variance: a measurement of the relative lengths of radius and ulna at the wrist. The distance
between two parallel lines drawn perpendicular to the long axis of the radius at the distal articular
surface of the ulna and the ulnar corner of the sigmoid notch of the radius. 60% of the population are
ulnar neutral.

10.  Capitolunate angle : A straight line drawn down third metacarpal shaft , capitate , lunate and shaft of
radius with wrist in neutral position on lateral radiograph which is 0 degree

12.  Scapholunate angle : The scapholunate angle is the angle between the long axis of the scaphoid and
the mid axis of the lunate . 30 to 70 degree

14.  Carpal height ratio : carpal height of proximal and distal carpal is 0.53 degree

16.  Palmar tilt : The volar tilt, or palmar/volar inclination, is an angle between a line drawn perpendicular
to the long axis of the radius and a tangential line drawn along the radial articular surface.

18. DEFINITIONS
 Dynamic stability : maintains normal alignment at rest but will collapse under applied load

19.  Static instability : abnormal intercarpal alignment on static radiograph

20.  Carpal instability : instability occurs between the individual bones. In the same row

22.  Carpal instability : instability occurs between the row of bones

23. THANK YOU