Distal Radius Frx: Dorsal Angulation 

- See:
            - Reduction of Dorsal Angulation

- Discussion:
    - measured on lateral, from angle created between articular surface of distal radius & line perpendicular to long axis of radius;
    - normal volar tilt measures between 0 to 22 degrees (mean 11 to 14.5 deg);
          - rare individuals may even have a dorsal tilt (which for them is normal);
    - dorsal tilt decreases moment arm of finger extensors, making wrist less efficienct;
    - w/ dorsal tilt deformity, there will be significant transfer of load onto ulna;
          - normally 82% of compressive load across the wrist is borne by radio-carpal joint, and 18% is borne thru the ulnocarpal joint;
          - w/ a 45-deg dorsal angulation deformity, 65 % of axial load across carpus is directed onto ulna;
          - remaining loads on radius will be concentrated on dorsal aspect of scaphoid fossa;

- Acceptable Reduction:
    - most orthopaedist will generally not accept any angulation past neurtal;
          - consider obtaining a lateral radiograph of the opposite wrist for comparison;
          - note that some patients may be predisposed to ulnar mid carpal instability, and hence, even an "acceptable reduction" w/ 5 deg volar tilt may cause symptoms;
                 - note whether there is abnormal dorsal tilt of the lunate;
    - as pointed out by Jupiter (1991), dorsal tilt greater than 20 deg will often become symptomatic w/ pain at radiocarpal articulation, as well as in limited grip strength, if angulation is not reduced;
    - when radial shortening occurs w/ dorsal tilt, there may be dysfunction of the distal R-U joint, manifested by limited rotation of forearm & impingement of ulna on radius;
    - Fractures of the distal end of the radius.
- Assoicatted Findings in Acute Injury:
    - see unstable distal radial frx;
    - in younger patients w/ distal radius frx, mid-carpal instability may be found in association w/ excessive dorsal tilt;
            - look for dorsal tilt of the lunate (DISI deformity);
    - comminution:
          - dorsal surface is frequently comminuted;
          - if comminution extends volar to midaxial plane of radius, then cast immobilization will frequently fail;
                 - expect increase in comminution w/ incr in amount of dorsiflexion;
                 - high-loading angles, (70-90 deg), have much more comminution than low loading angles of 20 to 40 deg;

- Effects of Chronic Dorsal Tilt:
    - in chronic cases, a malunion w/ excessive dorsal tilt may lead to ulnar mid carpal instability;
    - w/ healed fractures, symptotomatic dorsal angulation greater than 20 deg can be managed w/ a corrective opening wedge radial osteotomy

Midcarpal instability caused by malunited fractures of the distal radius.

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, August 7, 2012 2:26 pm