FEATURE ORTHOPAEDICS
fractures typically have a bimodal age distribution with fracture peaks occurring at 5-14 and 60-65 years old. Fractures in the younger group are usually the result of high-energy mechanisms (sports or road traffic accidents), whereas the older group sustain these fractures due to osteoporotic bone and low energy forces. There is a diversity of fractures patterns
of the distal radius and the many of the fracture eponyms used today are based on the authors who first described them. In 1838, John Rhea Barton first
described anterior and posterior fracture-dislocations of the wrist, which have since become known as volar and dorsal Barton’s fractures respectively. Volar Barton fractures occur more commonly than dorsal and are characterized by a fracture through the volar margin of the carpal surface of the radius with associated subluxation of the radiocarpal joint. Barton’s fractures are inherently
unstable and, in 1965, John Ellis suggested these fractures were best held in a reduced position using a small buttress plate secured to the lower radial shaft. He recommended that screws were to be inserted only into the proximal fragment and that the distal end of the plate would be acting purely as a buttress for the distal fragment. Buttress plates used for Barton’s fractures are pre-bent with an angulation of approximately 20 degrees to compensate for the shape of the distal radius. It has recently been suggested that
internal fixation using distal radius buttress plates offer a superior outcome compared to Kirschner wire and external fixation for Barton’s fractures.
CASE PRESENTATION A 53-year old, righthand dominant, female patient presented to the accident and emergency department with pain and deformity of her left wrist following a fall on to her outstretched hand. Examination demonstrated obvious
volar subluxation of the wrist with swelling and tenderness over the volar aspect of the distal radius. This was a closed injury and no neurovascular deficit was found. No other injuries were elicited. Antero-posterior and lateral x-rays of the
left wrist revealed a left volar Barton fracture. The patient was taken to theatre for
open reduction and internal fixation of her left volar Barton fracture. The operating surgeon turned over a right-sided AO stainless steel distal radius buttress plate and bent the angulation from dorsal to volar distally to fix the fracture. Post- operative check x-ray was satisfactory. 13 months later the patient was seen
in clinic following a trivial injury with pain and deformity in her left wrist. Examination demonstrated no swelling, but tenderness over the dorsal aspect of the distal radius. X-rays now revealed a left Colle’s fracture (dorsal displacement of the distal radius) with the plate still fixed. The patient was again taken to theatre and during intra-operative repair it was observed that despite the deformity the fracture site had healed. The plate was removed and it was noted that it had been put on upside-down. The fracture was reduced and a new stainless steel buttress plate was used to fix the fracture. The patient has made a good recovery of left wrist function post operatively. The buttress plate that was removed has since been sent for metal analysis.
DISCUSSION The plate deformation caused by the operating surgeon was elastic and the recoil to its original shape resulted in gradual transformation of the left volar Barton fracture to a left Colle’s fracture. A material is said to be elastic if it
deforms under stress and returns to its original shape when the stress is removed. The amount of deformation is the strain. This phenomenon can be explained using Young’s modulus of elasticity (E), a measure of a material’s resistance to elastic deformation, whereby E=stress/ strain. Approximate values for stainless steel and bone are 200x109 9x109
N/M2 N/M2 and respectively. This explains the
greater elasticity exerted by the plate effectively ‘pulling’ the bone across the healed fracture site. It is essential that manufacturers inform
orthopaedic surgeons not to inversely bend the angulation of the pre-bent stainless steel distal radius buttress plates otherwise a gradual deformation at the fracture site will inevitably occur. ■
AH
REFERENCES References available on request (
magazine@informa.com)
FIGS 1, 2a, 2b 1
1A
2a
2b
FIG 1: The AO stainless steel distal radius buttress plate removed from the patient FIG 2a: Post operative check x-rays following an open reduction and internal fixation using a pre-bent stainless steel distal radius buttress plate to fix a volar Barton fracture. The plate had been bent against its angulation from dorsal to volar distally. FIG 2b: Repeat x-rays 13 months later reveal the distal radius buttress plate had returned to its original shape, thereby causing a left Colle’s type fracture with the plate still fixed.
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The 8th Middle East Orthopaedics conference, running during Arab Health 2012, will offer delegates a three day review and update, covering pressing clinical issues in the management of musculoskeletal trauma, sports injuries, degenerative diseases and congenital disorders. To attend the event, visit the Al Wasl foyer between halls 4 and 5 at Arab Health to register as a delegate.
Arab Health Show Issue 2012 107
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