This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
This fracture, though rare, occasionally occurs, and if union has taken place the deformity is marked and the injury is liable to be diagnosed as a luxation. It has been particularly described by Dr. John B. Roberts (" A Clinical, Pathological, and Experimental Study of Fracture of the Lower End of the Radius with Displacement of the Carpal Fragment toward the Flexor or Anterior Surface of the Wrist," Phila., 1897 ). On account of the difficulties in diagnosis it is well to examine its anatomical peculiarities.
The lower fragment is tilted forward toward the palmar surface of the wrist, carrying the radial side of the hand with it (Fig. 356).
The line of the radius can be followed and felt to curve at its lower portion toward the palmar surface. The hand descending with the displaced fragment causes a groove to appear across the dorsum from one styloid process to the other. The dorsal surface of the lower part of the forearm is on a higher plane than that of the carpus. As the hand is lower than normal this causes the lower end of the ulna to project much higher than it should. On account of the tension of the extensor carpi radialis longior and brevior the hand is held level with the forearm and does not droop as in Colles's fracture. Displacement to the radial side may or may not be marked.
Fig. 355. - Epiphyses of the lower ends of the radius and ulna; union occurs with the shaft of the bones at about the 20th year.
Fig. 356. - Fracture of the lower end of the radius with displacement of the lower fragment toward the palmar surface. (Sketch, by the author, of a specimen in the Mutter Museum of the Philadelphia College of Physicians).