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SURGICAL TECHNIQUE

Modular tension band system for posterior fixation of the occipito cervical spine, upper and lower cervical spine, and upper thoracic spine

CERVIFIX

Instruments and implants approved by the AO Foundation.This publication is not intended for distribution in the USA.

Image intensifier control

WarningThis description alone does not provide sufficient background for direct use of DePuy Synthes products. Instruction by a surgeon experienced in handling these products is highly recommended.

Processing, Reprocessing, Care and MaintenanceFor general guidelines, function control and dismantling of multi-part instruments, as well as processing guidelines for implants, please contact your local sales representative or refer to:http://emea.depuysynthes.com/hcp/reprocessing-care-maintenanceFor general information about reprocessing, care and maintenance of Synthes reusable devices, instrument trays and cases, as well as processing of Synthes non-sterile implants, please consult the Important Information leaflet (SE_023827) or refer to: http://emea.depuysynthes.com/hcp/reprocessing-care-maintenance

CerviFix Surgical Technique DePuy Synthes 1

TABLE OF CONTENTS

INTRODUCTION Features and Benefits 2

AO Principles 4

Indications and Contraindications 5

PRODUCT INFORMATION Implants 6

Instruments 9

Set 11

SURGICAL TECHNIQUE Occipito-Cervical Stabilization 12

Fixation of Lower Cervical Spine 21

BIBLIOGRAPHY 26

2 DePuy Synthes CerviFix Surgical Technique

FEATURES AND BENEFITS

INDIVIDUAL SCREW PLACEMENT

CerviFix is a modular tension band system for posterior fixation of the occipitocervical spine, upper and lower cervical spine, and upper thoracic spine (T2). A choice of clamps are fixed on a rod by means of set screws. Bone screws can be optimally positioned through the clamps in the desired direction at each level.

Freedom of clamp positioning on the rod lets you choose the anatomically optimal screw entry sites.

T1–T2

C2

C2


SECURE SCREW SETTING

CLEVER SOLUTIONS

Three different clamp angles, according to Magerl trajec-tories, allow deep, secure anchorage in the lateral masses of C2 and C3–C7, and in the pedicles of T1–T2.

• Lateral rods allow maximum space for extensive bone grafting.

• Lamina bridging for dura protection after laminectomy.• Lamina hooks for osteoporotic vertebrae.


In 1958, the Association for the Study of Internal Fixa-tion (AO) formulated four basic principles1, which have become the guidelines for internal fixation. They are:

• Anatomical reduction• Stable internal fixation• Preservation of blood supply• Early, active pain-free mobilization

The fundamental aims of fracture treatment in the limbs and fusion of the spine are the same. A specific goal in the spine is returning as much function as possible to the injured neural elements.

AO Principles as applied to the spine2

Anatomical reductionRestoration of normal spinal alignment to improve the biomechanics of the spine.

Stable internal fixationStabilization of the spinal segment to promote bony fusion.

Preservation of blood supplyCreation of an optimal environment for fusion.

Early, active pain-free mobilizationMinimization of damage to the spinal vasculature, dura, and neural elements, which may contribute to pain reduction and improved function for the patient.

AO PRINCIPLES

1 Müller ME, Allgöwer M, Schneider R, Willenegger H (1995) Manual of Internal Fixation. 3rd, exp. a. completely rev. ed. 1991. Corr. 3rd printing. Berlin, Heidelberg, New York: Springer

2 Aebi M, Thalgott JS, Webb JK (1998) AO ASIF Principles in Spine Surgery. Berlin, Heidelberg, New York: Springer


Indications

Occipitocervical and upper cervical spine instabilities: • Rheumatoid arthritis • Anomalies• Posttraumatic conditions• Tumours• Infections

Instabilities in the lower cervical spine: • Posttraumatic instabilities• Tumours• Iatrogenic instabilities following laminectomy

Degenerative and painful posttraumatic conditions in the lower cervical spine

Anterior fusions requiring additional posterior stabilization

INDICATIONS AND CONTRAINDICATIONS

Contraindications

• Spinal destruction accompanied by loss of ventral support (caused by tumours, fractures and infections) results in major instability of the cervical spine and upper thoracic spine. In this situation, stabilization with CerviFix only is not sufficient. Additional anterior stabilization is crucial.

• Severe osteoporosis


Cortex Screws B 3.5 mm

• Titanium Alloy (TAN)• Spherical head• Core diameter 2.4mm• Self-tapping

Art. No. Length

404.310 10 mm

404.312 12 mm

404.314 14 mm

404.316 16 mm

404.318 18 mm

404.320 20 mm

404.322 22 mm

404.324 24 mm

404.326 26 mm

404.328 28 mm

404.330 30 mm

404.332 32 mm

404.334 34 mm

404.336 36 mm

404.338 38 mm

404.340 40 mm

404.345 45 mm

404.350 50 mm

IMPLANTS


C2 Clamps (TAN)

Art. No. Angulation

498.920 Right

498.921 Left

C3/C7 Clamps (TAN)

Art. No. Angulation

498.930 Right

498.931 Left

Pedicle Clamp (TAN)

Art. No. Angulation

498.955 Neutral

Lamina Clamps (TAN)

Art. No. Angulation

498.950 Right

498.951 Left

Hooks, Titanium Alloy (TAN)

Art. No. Angulation

498.942 Right, small

498.943 Left, small

498.940 Right, large

498.941 Left, large

Set Screw with Cone

Art. No.

498.002


Implants

Rods B 3.5 mm• Available in lengths 80, 120 and 240 mm• Titanium Alloy (TAN) / Pure Titanium (TiCP)

Art. No. Length Material

498.120 80 mm TAN

498.925 80 mm TiCp

498.125 120 mm TAN

498.926 120 mm TiCp

498.957 240 mm TiCP

Occiput RodB 3.5 mm• Available length 240 mm• Pure Titanium (TiCp)

Art. No.

498.956

Connecting Rods• Available in lengths 300 and 500 mm• Pure Titanium (TiCp)

Art. No. Length B

498.936 300 mm 3.5/5.0 mm

498.937 300 mm 3.5/6.0 mm

498.938 500 mm 3.5/5.0 mm

498.939 500 mm 3.5/6.0 mm

Parallel Connectors• Titanium Alloy (TAN)

Art. No. B

498.935 CerviFix Parallel Connector, gold 3.5/3.5 mm

498.959 Parallel Connector for USS Small Stature/Paediatric, light blue, 3.5/5.0 mm

498.960 CerviFix Parallel Connector 3.5/6.0 mm


INSTRUMENTS

312.860 Handle for Drill Guide Inserts, for Nos. 312.840, 312.870 and 312.880

312.880 Drill Guide Insert 3.5, with Knurled Nut, for No. 312.860

315.630 Drill Bit B 2.5 mm, length 160/135 mm, 3-flute, for Quick Coupling

388.017 Drill Guide Insert 2.7, calibrated, with Knurled Nut, for Nos. 312.860 and 315.630

311.330 Tap for Cortex Screws B 3.5 mm

311.440 T-Handle with Quick Coupling

319.010 Depth Gauge for Screws B 2.7 to 4.0 mm, measuring range up to 60 mm • For depth measurement through

the plate


Instruments

388.020 Screwdriver, hexagonal, small, self-holding

388.868 Trial Rod B 3.5 mm

388.000 Trial Rod B 2.8 mm, length 240 mm, for CerviFix

388.869 Occiput Trial Rod B 3.5 mm

388.016 Rod Cutter, for Rods B 3.5 mm

388.005 Bending Pliers for Rods B 3.5 mm and Plates 3.5



388.015 CerviFix Compression Forceps for Rods B 3.5 mm

Set

687.000 Vario Case for CerviFix, with Lid, without Contents

2

8

1 1

9

7

9

4 5 6 13 3

10

12

11


PositioningThe patient is placed in a prone position.

ReductionReduction of C1 on C2 is performed when indicated, using image intensification.

ApproachSubperiosteal exposure of occiput, posterior atlas ring, posterior elements of C2, spinous processes, vertebral arches, and articular masses of those lower cervical spine vertebrae to be included in the fusion. For a transarticu-lar screw fixation of C1/C2, the isthmus of C2 must be exposed on both sides.

1 Semispinalis capitis muscle 2 Semispinalis cervicis muscle 3 Superior oblique muscle of the head 4 Smaller straight muscle of the head 5 Greater straight muscle of the head 6 Inferior oblique muscle of the head 7 Posterior arch of the atlas 8 Zygapophyseal articulations 9 Vertebral artery10 Occipital artery11 Third occipital nerve12 Greater occipital nerve13 Suboccipital nerve

OCCIPITO-CERVICAL STABILIZATION


1Bending the rod

Instruments

388.869 Occiput Trial Rod B 3.5 mm



Optional instruments



Bend the template in such a way that its cranial end, ad-jacent to the midline, is situated just caudal to the protu-berantia occipitalis externa, and that the rod passes over the lateral rims of the articular processes of C2, C3, etc.

Bend and cut the occipital rod according to the template and confirm the correct fit in situ.

Note: Titanium rods are weakened when being bent back and forth.


Occipito-Cervical Stabilization

2Instrumenting C1/C2

Instruments




388.017 Drill Guide Insert 2.7, with calibrated with Knurled Nut, for Nos. 312.860 and 315.630

If necessary, reduce a C1/C2 dislocation under image in-tensification and drill the screw holes on both sides for a trans articular C1/C2 fusion using the Magerl technique. In order to provisionally stabilize C1/C2, leave the drill bit in situ on one side while drilling and instrumenting the other side.


3Instrumenting the most caudal vertebra

Instruments





311.330 Tap for Cortex Screws B 3.5 mm, length 180/110 mm

Drill the screw hole in the most caudal vertebra to be stabilized using the Magerl technique. Tap the near cortex only.



4Provisional clamp mounting

Instruments


388.011 CerviFix Holding Forceps for Rods B 3.5 mm

Provisionally mount and slightly fasten all necessary clamps on the rod.

5C1/C2 screw insertion

Instruments

319.010 Depth Gauge for Screws B 2.7 to 4.0 mm, measuring range up to 60 mm




Measure the length of the C1/C2 transarticular screw through its corresponding clamp. Tap and insert the screw. Choose a screw that is a little too short rather than one that is too long.


6Occipital screw insertion

Instruments








Drill three occipital screw holes, measure the screw length through the plate. Tap and insert the screws.


7Caudal screw insertion

Instruments




Insert the most caudal screw of the assembly.



8Intermediate screw insertion

Instruments








Through the corresponding clamps, drill the screw holes for the intermediate clamps between C2 and the most caudal element. Tap and insert the screws.



9Insert second occiput rod accordingly

Repeat steps 1 to 8.

10Bone grafting

Apply cancellous bone graft. Between the occiput and the spinous process of C2, a corticocancellous bone graft is inserted acting as a buttress.

Postoperative care

A Philadelphia collar is worn for a period of 12 weeks. It may be removed for daily care and while resting. If no cancellous bone graft has been applied (for tumour cases only, when bone cement is used!), an orthosis must be worn for life.


Positioning

The patient is placed in a prone position.

Approach

Perform a midline incision, subperiosteally expose the spinal processes, laminae, and articular masses of the vertebrae to be included in the fusion.

1Bending the rod

Instruments






Measure the rod length, cut and slightly contour the rod in lordosis.

Note: Titanium rods are weakened when being bent back and forth.

FIXATION OF LOWER CERVICAL SPINE


2Instrumenting the most cranial and most caudal vertebrae

Instruments






Drill the screw holes for the most cranial and most cau-dal clamps using the Magerl technique. Tap the near cor-tex only.

3Clamp mounting

Instruments



Mount all the planned clamps on the rod.

Fixation of Lower Cervical Spine


4Caudal and cranial screw insertion

Instruments

319.010 Depth Gauge for Screws B 2.7 to 4.0B mm, measuring range up to 60B mm





388.015 CerviFix Compression Forceps for Rods B 3.5 mm

Measure the screw length through the clamps. Tap the near cortex and insert the most caudal screw, then the most cranial. If you desire slight posterior compression (lordosis), bring the cranial clamp closer to the caudal one and fix it to the rod. The cranial screw will cause in-tersegmental compression and lordosis when tightened.


Fixation of Lower Cervical Spine

5Instrumenting the intermediate vertebrae

Instruments









Drill the intermediate screw holes through the clamps. Tap and screw in the corresponding screws.

6Insert second occiput rod accordingly

Repeat steps 1 to 5.


7Mounting a laminar substitute

Instruments



To increase rotational stability, to protect the dura after laminectomies, and to suture the musculature, mount a laminar substitute.

8Bone grafting

Apply cancellous bone graft on the articular processes.

9Wound closure

Close the wound. The musculature may be sutured to the laminar substitute.

Postoperative care

Immobilization of the cervical spine for 8 weeks in a Philadelphia collar which can be removed for resting.


Jeanneret B, Magerl F, Ward EH, Ward JC (1991) Poste-rior Stabilization of the Cervical Spine with Hook Plates. Spine 16 (3S): 56–63

Jeanneret B (1992) Posterior Fusion of the Cervical Spine. Spine: State of the Art Reviews 6 (3)

Jeanneret B (1994) Posterior Transarticular Screw Fixation of C1–C2. Techniques in Orthopaedics 9 (1) 1994

Jeanneret B (1996) AO Posterior Rod System of the Cervical Spine: a new implant allowing optimal screw insertion. Eur Spine J 5 (5): 350–356

Sasso RC, Jeanneret B, Fischer K, Magerl F (1994) Occipi-tocervical Fusion with Posterior Plate and Screw Instru-mentation: a long-term follow-up study. Spine 19 (20): 2364–2368

Müller ME, Allgöwer M, Schneider R, Willenegger H (1995) Manual of Internal Fixation. 3rd, expanded and completely revised ed. 1991. Berlin, Heidelberg, New York: Springer

BIBLIOGRAPHY

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Synthes GmbHEimattstrasse 34436 OberdorfSwitzerlandTel: +41 61 965 61 11Fax: +41 61 965 66 00www.depuysynthes.com

Not all products are currently available in all markets.

This publication is not intended for distribution in the USA.

All surgical techniques are available as PDF files at www.depuysynthes.com/ifu ©

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