Building a Sheffield Ring Fixator Construct for a deformity correction

The problem: a lower third tibial malunion at two levels from two separate fractures.
The solution: an oblique plane correction at the lower level, lengthening, derotation and finally correction of residual translation.
The oblique plane is deformity is measured to be 18 degrees (16 degrees valgus and 8 degrees anterior angulation) 7 cm from the ankle joint. The ring is laid over the tracing with the front of the ring anterior on the tracing to identify the position of the motor and hinges). Rotation translation hinges are selected to facilitate subsequent corrective stages. Since the ring is 15mm thick, its lower most wire 2mm below this and positioned 5mm above the joint the hinge is placed 48mm above the ring.
The second hinge is applied at the same height and correct orientation confirmed by placing a 2mm wire through the cannulation of the two hinges.
Three long threaded bars are inserted tempoarily in holes that will not be used and a second ring is mounted using the same holes.
The hinges are locked and a motor built from two hinge clamps applied at right angles to the hinges.
The temporary bars are removed, the hinges unlocked, and smooth movement of the frame confirmed from the deformed to the corrected position.