Seligson [1] describes how Hoffmann and Jaquet, a medical doctor and an engineer, respectively, developed the original Hoffmann fixator as a tool to stabilize human fractures with minimal invasiveness.
Whether being utilized in mass trauma injury situations such as the 2010 Haitian earthquake, within our emerging geriatric population, or in veterinary applications, external fixation is widely used [1–4]. In this investigation, a rod-to-wire coupling, shown in Figure 1, and hereafter referred to as the R2W clamp, has been designed and validation tested for Stryker Orthopaedic’s Hoffmann II (HII) External Fixation System. As the name implies, this clamp has the purpose of connecting 8mm rods to 1.5mm or 2mm Kirschner (k-) wires or olive wires to stabilize bony fragments in the lower extremity, thus expediting healing in a trauma case. This paper summarizes the results of the validation tests conducted on prototype clamps.
This clamp effectively allows placement of a wire to further stabilize a frame [3] by allowing wire placement without the addition of an intermediate ring, as shown in Figure 2. The wire could be added to any configuration with two parallel rods extending in plane with the bone.
As shown in Figure 3, the R2W clamp can be positioned “outboard” with the rod between it and the bone, or “inboard” between the rod and the bone, allowing the surgeon geometric flexibility. The use of two k-wires is recommended to stabilize each bone fragment [5].
One of the goals of the validation testing was to determine the effectiveness and functional safety of the clamp as related to surgically applied k-wire tensions of either 50 kg or 100 kg.
Since it is feasible that surgeons may tighten, loosen, then retighten the clamp while positioning it during surgery, the effects of clamp retightenings on the performance of the R2W clamp were also evaluated [4].
