MatrixNeuro Ultra Low Profile (ULP)

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MatrixNeuro Ultra Low Profile (ULP)

Fig 1 MatrixNeuro ULP implants.

The MatrixNeuro system was developed in 2008 to offer a complete system for use in craniotomies, cranial trauma repair, and reconstruction of the craniofacial skeleton. Although it provided the lowest profile of plate and screw of its kind at that time, patients continued to require an even lower profile. Many patients find that plates can still be felt or seen as lumps under the skin. This is increasingly significant due to the growing number of procedures that include the frontal area, which, according to Prof Christian Matula, Chair of the Neuro Trauma Reconstruction Expert Group (NTREG) "is an area that the patient looks at every day in the mirror and any abnormality can make them feel unhappy". In addition, the unconscious rubbing of plates can lead to other skin issues.

The new MatrixNeuro Ultra Low Profile (ULP) system (Fig 1) was developed in response to the need to decrease implant profile whilst also providing comparable construct stiffness and strength to the plates in the existing MatrixNeuro system.

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The plate thickness is only 0.28 mm (MatrixNeuro standard plates are 0.40 mm). Also, the screw recess was improved (Fig 2) to achieve a better seating of the screw, which has led to a plate-screw profile of 0.44 mm, a reduction of another 10% compared with the existing system. And instead of having a rectangular edge, the plates are chamfered to achieve almost no palpability under the skin (Fig 3).

The new MatrixNeuro ULP system is fully compatible with the existing MatrixNeuro system so that no new or specific instruments are needed, and the same surgical techniques are used. Furthermore, all implants are fixated with the already existing self-drilling screws from the MatrixNeuro system, which have a unique thread design for rapid screw starting and significantly lower insertion torque. The screws start with bone contact almost instantaneously providing a fast closure of bone flaps and rapid fixation of cranial fractures.

Fig 2ab Screw recess modified for more plate-screw contact (better seating) and lower profile.

Fig 3 Chamfered edges on the ULP implants (green).

A wide range of plates is available (Fig 4) based on the most frequently used MatrixNeuro standard plates, ie, Burr Hole Covers ranging from 1224 mm with one additional version for shunt or drainage, as well as straight plates with center space in 2-hole and 4-hole versions. The system is completed with an X Plate, a square and a rectangular Frame Plate, a Double Y Plate, and a Strut Plate.

Fig 4 Selection of implant shapes.

Case: Apert Syndrome

An 8-year-old girl with Apert Syndrome (Fig 5) was examined after being treated at another institution. The cause for loss of cranial bone was unknown. An anterior and posterior cranial expansion was given to treat the increased intracranial pressure.

Fig 5 An 8-year-old girl with Apert Syndrome (Fig 5)

After that healed, a simultaneous PSI cranioplasty and Le fort II osteotomy with zygoma repositioning were performed. The PEEK implants were fixated using MatrixNeuro ULP implants (Fig 6). A midface distraction device was then mounted on the PSI implants and distracted the Lefort 2 segment to treat the patient's sleep apnea (Fig 7).

Case provided by Richard Hopper, Seattle, USA.

Neurocranial Reconstruction

A presentation delivered by Christian Matula (Austria) and Stephen Lewis (Australia) in 2012.

Optimizing Surgical Cranial Access

A presentation delivered by Christian Matula (Austria) and Stephen Lewis (Australia) in 2017.

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