UniX® Metaphyseal Hinge Fixator

The UniX® Metaphyseal Hinge Fixator is a unilateral external fixator for gradual or acute correction of frontal-plane deformities of the proximal tibia, with a hinge that aligns to the center of the deformity and corrects up to 20° of varus or 10° of valgus.

Available in three sizes (small, medium, large) to match tibial anatomy, fixed with four conical 6 mm titanium half pins.

At 9 mm thick, it is one of the lowest-profile external fixators available, supporting patient comfort through the correction and consolidation period.

All-titanium construction keeps the frame lightweight and easier to maintain than a ring fixator, positioned over the region of thinnest soft tissue coverage at the knee.

Designed on the idea and patent of Prof. Rainer Baumgart MD, trauma surgeon and mechanical engineer.

Acute correction with a static plate does not account for how the surrounding ligaments react once the patient bears full load, which can leave the construct under- or over-corrected relative to the plan. Correcting from valgus to varus acutely can also stretch the peroneal nerve, risking drop foot.

Gradual correction with the hinge lets the surgeon adjust the angle under load, reducing the risk of over- or under-correction and nerve traction injury.

New bone forms by callus distraction, the same mechanism used in limb lengthening, rather than requiring a fixed osteotomy reduction at the time of surgery.

For open-wedge corrections, gradual distraction can avoid the need for iliac crest bone grafting.

UniPlasty® is Response Ortho's gradual opening-wedge high tibial osteotomy (HTO): a joint-preserving realignment technique built around the UniX® Metaphyseal Hinge Fixator, with four priorities for the surgeon and patient:

Minimally invasive — correction is achieved through small incisions rather than an open reduction.

No second open operation to remove an internal plate — after bone healing, the external fixator is taken off and only its four pins are removed, in a simple procedure.

Nothing left under the skin — UniPlasty® works without internal plates or screws; once the external fixator and its pins are removed, no implant remains in the body.

Accurate alignment — the adjustable hinge lets the surgeon fine-tune the correction under load, rather than committing to a single acute reduction.

After a post-operative waiting period of 5–7 days, the hinge is adjusted twice daily — 0.33° each time, for a combined 0.66° per day — until the planned correction is reached. Bone consolidation typically takes 2–3 months, bringing the frame's total time on the leg to approximately 3–4 months before removal, once radiographs confirm sufficient healing.

Patient information on bow legs, high tibial osteotomy and the UniPlasty® treatment stages is available at www.UniPlasty.com.

This product is CE-marked and has also been cleared by the FDA for distribution in the United States.