its axis a similar steinman pin may be inserted through complementary pilot hole 25 on the lateral side to further assist in rigidly mounting the clamp the ulna fixation assembly 26 is next mounted on the humeral clamp by means of u clamp 27 the ulna fixation assembly 26 comprises a telescopically expandable arm 28 lockable at any selected length by u clamp 29 a crosshead 30 is adjustably and clampingly mounted at the end of arm 28 by means of clamp 31 intermediate the ends thereof coronoid arms 32 33 extend substantially perpendicularly to arm 28 and to crosslead 30 at opposite ends thereof and angularly adjustable relative thereto intermediate the ends of crosslead 30 there is provided an olecranon bracket 34 which may be locked at any desired angle to arms 32 33 by means of locking screws 35 36 the olecranon bracket 34 is adjusted so that the adjustable pin clamp 37 lies adjacent the olecranon and a threaded steinman pin 38 may be inserted through clamp 37 and drilled not more than about 1 cm into the olecranon so that pin 38 is substantially parallel to the longitudinal axis of the ulna with the elbow flexed at about 45 u00b0 and held at that angle by a rigid telescopically adjustable bracket 83 and wrist 81 and humeral straps the linked parallel coronoid bracket arms 32 33 are adjusted.