Medial High Tibial Plate (TomoFix Anatomical)

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Medial High Tibial Plate (TomoFix Anatomical)

Michael Blauth, Hiroaki Minchara, J Spence Reid, Steffen Schröter, Theodor F Slongo

Fig 1: X-rays of HTO plate application in the same patient. a) AP view TomoFix MHT Standard first generation (right leg). b) AP TomoFix MHT Anatomical Left (left leg). c) Lateral view TomoFix MHT Standard first generation (right leg). d) Lateral view TomoFix MHT Anatomical Left (left leg).

The new generation of joint preserving technology TomoFix Anatomical

Joint-preserving therapies and specifically realignment osteotomy have been steadily gaining importance over the past decade. The combination of malalignment and unicompartmental osteoarthritis, most often encountered on the medial side, is a common problem which arises in all age groups. The high tibial osteotomy (HTO) is an established procedure for the treatment of knee osteoarthritis and can be performed through either an additive open wedge approach or a subtractive closed wedge procedure.

In 2001, the Knee Expert Group (KNEG) and AOTK in collaboration with Synthes, approved the world's first open wedge high tibia valgisation osteotomy system with plate fixator. It was named TomoFix and has remained a global market leader in the field of joint preservation and knee osteotomy for fourteen years.

Earlier this year, the AOTK approved a next generation of TomoFix in the form of a new Medial High Tibial Plate indicated for:

Unicompartmental medial or lateral gonarthrosis with malalignment of the proximal tibia.
Idiopathic or posttraumatic varus or valgus deformity of the proximal tibia.

The TomoFix knee osteotomy system is based on the trusted locking compression plate (LCP) technology, enabling angular stable connections between the screws and the plate. This angular stability allows the stable fixation of an osteotomy intended for early and safe mobilization in accordance with AO principles.

The TomoFix Anatomical Medial High Tibial Plate is contoured to provide an anatomical fit. When compared with the TomoFix Standard and small plates, the new design is intended to reduce both implant prominence
and postoperative implant irritation. Fig 1 shows x-rays from one patient.

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Features include:

The 5° slant of the plate helps achieve parallel fixation of the proximal plate to the plateau slope of smaller statured tibia (Fig 2)
The new plate shape facilitates plate placement towards the medial side, providing support on the medialposterior edge of the tibial plateau. This also functions to help prevent neurovascular damage
caused by possible screw protrusion (Fig 3)
The TomoFix MHT plate is designed to accommodate both small and large oblique osteotomies

Fig 2: The TomoFix MHT plate.

Fig 3: The new plate shape facilitates the support on the medialposterior edge of the tibial plateau.

Not only does the new TomoFix Knee Osteotomy System contain a new MHT plate with more anatomical features, it also includes new osteotomy instrumentation intended to improve both surgical accuracy and procedural efficiency. The new instrumentation is compatible with the existing Standard and small TomoFix Medial High Tibia plates. Fig 4 shows a patient with post-traumatic deformity after a proximal tibial fracture (at the 6-week follow-up after open wedge HTO in descending technique and fixation with the TomoFix MHT anatomical plate).

Fig 4: Patient with post-traumatic deformity at the 6-week follow-up.

High tibial osteotomy is a technically demanding procedure. Complications commonly include postoperative malalignment, imprecise correction, and damage to the tibial dorsal neurovascular structures. Correcting malalignment to the desired angle with precision is a key element of the surgery. The new TomoFix Osteotomy Instrumentation is intended to assist surgeons to define the osteotomy line and maintain steady sawing during the osteotomy cut. Additionally:

The aiming arm and K-wire guide support the insertion of K-wires to help maintain tibial slope and aim at the hinge points (Fig 5)
The saw guide allows surgeons to perform biplanar osteotomy under x-ray guidance (Fig 6)
The radiolucent retractor is intended to protect the posterior neurovascular structures while sawing (Fig 7)

Fig 5: Aiming arm and K-wire guide.

Fig 6: Saw guide.

Fig 7: Radiolucent retractor.

Innovations in osteotomies around the knee

Presentation delivered by S. Schröter (DE), R. Takeuchi (JP) and S. Döbele (DE), introducing Innovations in osteotomies around the knee.

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