The Hynes and Giddins device was initially described in 2001 but has undergone modification since. It is a dynamic external fixator allowing stabilisation of periarticular fractures while maintaining PIPJ movement. (Journal of Hand Surgery, British and European Volume, 2001; 26B: 2: 122–124)
Principle
This frame is best applied to periarticular fractures of the base of the middle phalanx. It allows for distraction of fracture fragments and offloads the PIPJ that it traverses. It allows rotation around a fixed point therefore maintaining PIPJ inline mobilisation and reducing the risk of stiffness. A long and a short K-wire are required. The short wire becomes the pivot of rotation and the long wire provides the distraction force.
Technique
Step 1 – The short wire is passed through the head of the proximal phalanx at the origin of the collaterals which is the centre point of rotation around the P1 head.
Step 2 – The long K-wire is passed through the shaft of the middle phalanx beyond the fractures in the same transverse plane perpendicular to the axis of the bones. There should be an equal length of wire on each side of the bone.
Step 3 – The long distal K-wire is clamped as it exits the bone, and bent dorsally on each side, until the tips almost touch. These ‘arms’ of the long wire are then rotated to touch the short wire. A clamp is applied beyond the intersection and the ‘arm’ is folded back on itself.
Tip: It is helpful to repeat each manoeuvre immediately on the other side to ensure symmetry.
Step 4 – A second fold is now placed in each arm to create a ‘Z’.
Step 5 – The transverse wire can now be hooked inside the ‘Z’ fold by arching the long K-wire ‘arms’ and loading them with tension. This has the effect of ‘pushing’ the short wire away, creating a distraction force.
Tip: The amount of ‘push’ can be altered by opening or closing the ‘Z’ angles.
Step 6 – The short wire is then also bent to stop the Z arms from disengaging. The ends can be trimmed short.
A check image on the Image Intensifier/C-arm will show whether the joint is over or under distracted.
Note: Remember that with this device the joint is being distracted by this process of LIGAMENTOTAXIS. The fracture fragments are untouched and allowed to rest back into their anatomical position by the ligaments which have tautened and so guide the fragments back into alignment. The joint space is de-tensioned.
Step 7 – In case of subluxation of the PIPJ use of a third wire is recommended. This needs to hook under the arms in the distal fragment to pull that fragment and joint back into alignment.
Tip: It is helpful to use two cannulae to protect the wire ends and stop them catching. Each plastic cannula (without needle) is cut from the hub and threaded over each pair of wire ends. The same effect can be produced using a butterfly needle or fine feeding tube.