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Fractures of the distal end of the radius.

Fractures of the distal radius , Fractures of the distal radius , کتابخانه دیجیتال جندی شاپور اهواز

Fractures of the distal radius.

In an attempt to explain disability in dorsally angulated malunited distal radius fractures, an experiment was designed to evaluate load patterns about the wrist with varying degrees of dorsal angulation of the distal radius. Osteotomies were made in the distal radius of fresh cadaver arms after a modified external fixator was applied to the radius and load cells applied to the proximal radius and ulna. Pressure-sensitive film was inserted into the radioulnar carpal joint. After a predetermined load was applied to the wrist it was found that the load through the ulna increased from 21 % to 67 % of the total load as the angulation of the distal radial fragment increased from 10° of palmar tilt to 45° of dorsal tilt. The pressure distribution on the ulnar and radial articular surfaces changed in position and became more concentrated as dorsal angulation increased.

A biomechanical study of distal radial fractures

An experimental model using a static positioning frame, pressure-sensitive film (Fuji), and a microcomputer-based videodigitizing system was used to measure contact areas and pressures in the wrist. Contact areas and pressures were compared in a group of wrists between the normal state and with simulated distal radius fracture malunions of varying degrees. In simulated malunions, radial shortening to any degree slightly increased the total contact area in the lunate fossa, and was significant at 2 mm of shortening. By angulating the distal radius more than 20 degrees either palmar or dorsal, there was a dorsal shift in the scaphoid and lunate high pressure areas, and the loads were more concentrated, but there was no change in the load distribution between the scaphoid and lunate. Decreasing the radial inclination shifted the load distribution so that there was more load in the lunate fossa and less load in the scaphoid fossa.

Effects of distal radius fracture malunion on wrist joint mechanics

Fractures of the distal end of the radius should be treated on the same principles as other fractures involving joints. Displaced articular fractures require open reduction to allow anatomical reconstruction of both the radiocarpal and the radio-ulnar joints. For extra-articular fractures with severe comminution and shortening this enables the radial length to be re-established achieving radio-ulnar congruency. Stable internal fixation can be achieved with two 2.0 AO titanium plates placed on each of the 'lateral' and the 'intermediate' columns of the wrist at an angle of 50 degrees to 70 degrees. This gives good stability despite the tiny dimensions of the plates, and allows early function. We report a series of 20 fractures treated by this method of internal fixation with satisfactory results in all.

Fractures of the distal end of the radius treated by internal fixation and early function : A preliminary report of 20 cases

Thirteen patients with malunited fractures of the distal radius developed symptoms of pain and instability of the midcarpal joint In six cases, a recurrent voluntary midcarpal subluxation was also present during ulnar deviation These symptoms were first noticed several weeks, and at times several months, after all immobilization for the treatment of the original fracture had been discontinued We believe that the loss of the normal palmar tilt of the distal articular surface of the radius prepositions the carpus in a dorsal collapse alignment, which enables this instability to develop Although the instability is localized to the midcarpus, it is treated best, in our opinion, by a corrective osteotomy of the distal radius In nine patients, osteotomies resulted in relief of preoperative symptoms and correction of midcarpal instability In one patient, osteotomy of the radius was deemed unnecessary because the loss of palmar tilt of the radius was minimal Instead the midcarpal (triquetrohamate) joint was stabilized by ligament reconstruction Only transient correction was obtained, with later recurrence of the voluntary midcarpal subluxation

H. Kirk Watson

Papers

Midcarpal instability caused by malunited fractures of the distal radius