Technique Guide. Prodisc-C. Modular intervertebral disc prosthesis for restoring disc height and segmental motion in the cervical spine.

Transcription

1 Technique Guide Prodisc-C. Modular intervertebral disc prosthesis for restoring disc height and segmental motion in the cervical spine.

2 Table of Contents Introduction Overview 2 Kinematics 3 Indications and Contraindications 4 Product Information Implants 5 Instruments 8 Surgical Technique Minimally Invasive Access, Simple and Safe 13 Surgical Technique Surgical Technique 14 Multi-Level Cases 24 Case Examples 25 Bibliography 27 Image intensifier control Warning This description alone does not provide sufficient background for direct use of the instrument set. Instruction by a surgeon experienced in handling these instruments is highly recommended. Note: Training by Synthes is mandatory. For more information please contact your local Synthes representative. Synthes 1

3 Prodisc-C. Modular intervertebral disc prosthesis for restoring disc height and segmental motion in the cervical spine. Proven concept from the field of joint endoprosthetics Tested materials Superior and inferior implant plate made of cobalt-chromium-molybdenum alloy Rough surface coating of pure titanium supports bony ongrowth within a few months Inlay made of ultra-high molecular weight polyethylene (UHMWPE) Ball and socket principle Permits a physiological range of motion in regard to flexion/extension, rotation, and lateral bending Restores anatomical balance Guided, controlled motion limits the load on facet joints Modular anatomical design Optimal primary stability due to keel anchorage of the prosthesis in the vertebral body Anatomical footprint design for maximum end plate coverage 2 Synthes Prodisc-C Technique Guide

4 Kinematics The kinematics correspond to the joint guidance in vertebral joints 1 : The center of rotation is located just below the superior end plate of the affected caudal vertebral body. The location of the center of rotation and the flexion radius correspond to the natural joint guidance in the vertebral joints. The physiological range of motion in regard to flexion/extension and lateral bending is restored. The axial rotation is limited only by the anatomical structures and not by the prosthesis. Pure translatory movements are not possible due to the ball and socket principle.. Flexion/extension 17 min Lateral bending 11 min Axial rotation White, Panjabi 1990 Synthes 3

5 Indications and Contraindications Prodisc-C implants are used to replace a cervical intervertebral disc and to restore disc height and segmental motion. Indications Symptomatic cervical disc disease (SCDD) Specific contraindications Fractures, infections, tumours Spinal stenosis by hypertrophic spondylarthrosis Facet joint degeneration Increased segmental instability Ossification of posterior longitudinal ligament (OPLL) General contraindications Osteoporosis, Osteochondrosis, and severe Osteopenia Acute or chronic systemic, spinal, or localized infections Systemic and metabolic diseases Any medical and surgical conditions precluding the benefits of spinal surgery Foreign body sensitivity to the implant materials Dependency on pharmaceutical drugs, drug abuse or alcoholism Pregnancy Severe obesity (Body Mass Index above 36) Lack of patient cooperation 4 Synthes Prodisc-C Technique Guide

6 Implants Dimensions M 8.7 mm MD/L 10.7 mm LD/XL 12.7 mm XLD 14.7 mm 2.0 mm 3.5 mm 1.8 mm 2.3 mm 3.5 mm 1.8 mm 3.0 mm Six different footprints are available for optimal coverage of the vertebral end plate: M, MD, L, LD, XL, XLD mm mm Panjabi /17/19 mm 12/14/16/18 mm Three different heights (5, 6, and 7 mm) allow adjustment to the individual dimensions of the patient s disc mm Yoganandan et al /6/7 mm Synthes 5

7 H-keel design H-keel is the actual design variation that is distributed since April It has an additional cavity at the posterior end of both keels. This cavity can lodge potential residual bone debris and thereby facilitates the posterior positioning of the implant. Implant M Width 15 mm Depth 12 mm Implant MD Width 15 mm Depth 14 mm 18 mm 16 mm 14 mm 12 mm Depth MD M LD L XLD XL Height Height SSC255H SSC256H 5 mm 6 mm SSC275H SSC276H 5 mm 6 mm Width 15 mm 17 mm 19 mm SSC257H 7 mm SSC277H 7 mm Implant L Width 17 mm Depth 14 mm Implant LD Width 17 mm Depth 16 mm Height Height SSC355H 5 mm SSC375H 5 mm SSC356H 6 mm SSC376H 6 mm SSC357H 7 mm SSC377H 7 mm Implant XL Width 19 mm Depth 16 mm Implant XLD Width 19 mm Depth 18 mm Height Height SSC455H 5 mm SSC475H 5 mm SSC456H 6 mm SSC476H 6 mm SSC457H 7 mm SSC477H 7 mm 6 Synthes Prodisc-C Technique Guide

8 Standard design Before March 2006 Prodisc-C was manufactured in a slightly different design without cavity in the posterior part of the keel. These implants are still available with the following article numbers: 18 mm 16 mm LD XLD XL Implant M Width 15 mm Depth 12 mm SSC205C Height 5 mm Implant MD Width 15 mm Depth 14 mm SSC225C Height 5 mm 14 mm 12 mm Depth MD M L SSC206C 6 mm SSC226C 6 mm SSC207C 7 mm SSC227C 7 mm Width 15 mm 17 mm 19 mm Implant L Width 17 mm Depth 14 mm Implant LD Width 17 mm Depth 16 mm Height Height SSC305C 5 mm SSC325C 5 mm SSC306C 6 mm SSC326C 6 mm SSC307C 7 mm SSC327C 7 mm Implant XL Width 19 mm Depth 16 mm Implant XLD Width 19 mm Depth 18 mm Height Height SSC405C 5 mm SSC425C 5 mm SSC406C 6 mm SSC426C 6 mm SSC407C 7 mm SSC427C 7 mm Synthes 7

9 Instruments The Prodisc-C instrument set was developed for a minimally invasive or microscopic procedure. Retainer screw system SFC800R Center Punch SFC810R Screwdriver SFC805R Vertebral Body Retainer The vertebral body retainer is used to maintain the distraction achieved with the vertebral distractor. This construct assures stabilization of the vertebral body for end plate preparation and implant insertion. Retainer screw 3.5 mm Retainer screw 4.5 mm SFC812R SFC814R SFC816R SFC818R Length of thread 12 mm 14 mm 16 mm 18 mm SFC813R SFC815R SFC817R SFC819R Length of thread 13 mm 15 mm 17 mm 19 mm SFC811R Retainer Nut SFC802R Vertebral Distractor, rough tip 8 Synthes Prodisc-C Technique Guide

10 Trial implant system Trial Implant M Height SFC251R 5 mm SFC261R 6 mm SFC271R 7 mm Trial Implant MD Height SFC255R 5 mm SFC265R 6 mm SFC275R 7 mm Trial Implant L Height SFC351R 5 mm SFC361R 6 mm SFC371R 7 mm Trial Implant LD Height SFC355R 5 mm SFC365R 6 mm SFC375R 7 mm Trial Implant XL Height SFC451R 5 mm SFC461R 6 mm SFC471R 7 mm Trial Implant XLD Height SFC455R 5 mm SFC465R 6 mm SFC475R 7 mm The adjustable stop provides a positive stop against the anterior portion of the vertebral bodies during chiseling and can be adjusted to permit the correct positioning of the trial implant. Adjustable Stop Trial Implant SFC500R M SFC501R MD SFC502R L SFC503R LD SFC504R XL SFC505R XLD SFC840R Handle for Trial Implant Synthes 9

11 Drilling system Before the keel cut is performed, the drilling system can be used to open the anterior cortex of the vertebrae and to remove some bone material. Drill guides Drill bits Height Type SFC338R 5 mm SFC341R Synthes SFC339R 6 mm SFC342R J-Latch SFC340R 7 mm SFC343R Mini Quick Chisel instruments The keel cutting chisel, guided by the trial implant, is used to prepare the position of the implant keel. The box cutting chisel is used to prepare the posterior end of the keel cut for the optimal insertion of the implant. Chisel, Keel Cutting Height SFC258R 5 mm SFC268R 6 mm SFC278R 7 mm Chisel, Box Cutting Height SFC257R 5 mm SFC267R 6 mm SFC277R 7 mm SFC850R Wing for Chisel SFC860R Chisel Cleaning Plate SFC825R Mallet SFC320R Keel Cut Cleaner 10 Synthes Prodisc-C Technique Guide

12 Position gauge system After the keel cut was performed with the box cutting chisel, and the trial implant has been removed, position gauges can be used to check the correct depth and the parallelness of the keel cuts. Position Gauge M Height SFC252R 5 mm SFC262R 6 mm SFC272R 7 mm Position Gauge MD Height SFC256R 5 mm SFC266R 6 mm SFC276R 7 mm Position Gauge L Height SFC352R 5 mm SFC362R 6 mm SFC372R 7 mm Position Gauge LD Height SFC356R 5 mm SFC366R 6 mm SFC376R 7 mm Position Gauge XL Height SFC452R 5 mm SFC462R 6 mm SFC472R 7 mm Position Gauge XLD Height SFC456R 5 mm SFC466R 6 mm SFC476R 7 mm Shaft for Position Gauges Position Gauge SFC506R all Synthes 11

13 Insertion instruments SFC602R Implant Inserter, Scissors The pre-assembled and sterile packed Prodisc-C prosthesis can be easily secured on the implant inserter. Spacer for Implant Inserter, radiolucent SFC615R SFC616R SFC617R Height 5 mm 6 mm 7 mm Removal instruments SFC601R Implant Remover, Scissors 12 Synthes Prodisc-C Technique Guide

14 Minimally Invasive Access, Simple and Safe Surgical Technique The instruments are simple and safe to handle: Vertebral body retainer for fixing the vertebral body Trial implant with an adjustable stop Orientation at the midline for precise implanting The prosthesis can be inserted in simple steps due to the pre-assembled polyethylene inlay Early mobilization of the patients and short hospital stay due to minimal invasive access 1. Orientation at the midline 2. Insertion of trial implant 3. Guidance of chisels over trial implant 4. Final positioning of the prosthesis Synthes 13

15 Surgical Technique 1 Patient positioning Please ensure that the neck of the patient is firmly positioned, using a cushioned but not too soft roll. When treating C6 C7 make sure that the shoulders do not limit the x-ray monitoring. Both vertebrae have to be completely visible. 2 Access Expose the intervertebral disc and the adjacent vertebral bodies through a standard anterolateral approach to the cervical spine. Mark the level of the surgery and expose the intervertebral disc segment. Determine the midline using image intensifier control and make a permanent midline mark. 14 Synthes Prodisc-C Technique Guide

16 3 Fix retainer screw system Instruments SFC800R SFC810R SFC805R SFC812R 819R SFC811R Center Punch Screwdriver Vertebral Body Retainer Retainer Screw Retainer Nut Perforate the anterior cortex in the midline with the center punch in the upper third of the superior vertebra and in the lower third of the inferior vertebra. Ensure the spacing of the holes allows for the height of the implant keel. Insert the retainer screws bicortically in the upper or lower third of the respective vertebral body parallel and adjacent to the end plates. Begin with the smaller diameter screw of the longest possible length. Use the larger diameter screw when extra bone purchase is needed. Note: Insert screws under image intensifier control. Attach the vertebral body retainer away from the working zone and secure it with the retainer nuts. Synthes 15

17 4 Mobilize segment Instrument SFC802R Vertebral Distractor, rough tip Perform a complete discectomy and decompression. Remove intervertebral disc tissue and cartilage fragments from the end plates. Care should be taken to minimize bone remodeling. Distract the intervertebral space with the vertebral distractor in a parallel manner to restore the height and to gain access to the posterior intervertebral space. Readjust the vertebral body retainer to the distracted height of the intervertebral space. Continue the discectomy and decompression. Notes: Avoid over-distraction with the vertebral distractor as this can lead to nerve root tension or improper implant selection. Avoid using the vertebral body retainer as a distractor. Excess force on the vertebral body retainer can lead to bending and pull out of the screws from bone. Avoid excessive end plate removal. Excessive end plate removal increases the risk of implant subsidence. Ensure the cartilageous tissue is removed from the end plates. Cartilageous tissue may prevent osseointegration of the implant and reduce the fixation strength. 16 Synthes Prodisc-C Technique Guide

18 5 Insert the trial implant Instruments SFC500R 505R Adjustable Stop Trial Implant see Instruments page 9 SFC840R SFC825R Handle for Trial Implant Mallet Assemble the trial handle to the adjustable stop. The movable stop should be positioned closest to the trial implant as possible. Insert the trial implant under image intensifier control to determine the appropriate implant size, height and position. Align the trial implant at the midline. The goal is to select the largest footprint possible and the smallest height necessary. The implant should cover the majority of the vertebral body end plate. Undersized implants lead to increased risk of implant subsidence. 1 rev 0.5 mm The trial implant must be positioned at the posterior wall of the vertebral body. If it is not deep enough it can be positioned deeper by turning the adjustable stop counter clockwise (1 rev = 0.5 mm). Briefly release the vertebral body retainer to determine the optimal implant height. The trial implant should be lightly secured by the end plates of the adjacent vertebral bodies. If the implant is seated too loosely in the intervertebral space, select the next higher size. Check the position of the trial implant under lateral and AP image intensifier control. Notes: The shaft of the trial implant (stop included) must be screwed on completely. Avoid compression of the posterior elements during trial insertion. If in doubt of the correct trial size, try the smaller one. Avoid over-distraction by oversized trials as this can result in facet irritation and nerve root tension. The limit for the positioning of the trial is the posterior line of the vertebral body. The trial must not be placed any further posterior. Check CT for the posterior form of the vertebral bodies to ensure that the posterior end on the x- ray matches the actual posterior ends of the vertebral bodies. Synthes 17

19 6 Keel cut preparation A Drilling for keel cut preparation The use of special drill guides and drill bits is recommended in all cases, especially for sclerotic bone. Instruments SFC338R SFC339R SFC340R SFC341R SFC342R SFC343R Drill Guide, Height 5 mm Drill Guide, Height 6 mm Drill Guide, Height 7 mm Drill Bit, Synthes Drill Bit, J-Latch Drill Bit, Mini Quick Choose the correct drill guide according to the heigth of the trial implant. Insert the drill guide over the shaft of the trial implant until the mechanical stop is reached. Note: The drill guide must be inserted up to the mechanical stop. Otherwise the drilled hole risks to be too short. Attach the drill bit with quick coupling to a power tool like Colibri or E-Pen. Insert the drill bit through the drill guide. On both sides of the trial implant drill a hole in the vertebrae to open the cortex and prepare the vertebral bodies for the chiseling procedure. Drill until the mechanical stop is reached. Remove drill bit and drill guide Note: Synthes recommends a single use of the drills bits. 18 Synthes Prodisc-C Technique Guide

20 B Chiseling the keel cut Instruments SFC2x8R* SFC2x7R* SFC850R SFC825R Chisel, Keel Cutting, Height 5, 6, or 7 mm Chisel, Box Cutting, Height 5, 6, or 7 mm Wing for Chisel Mallet * x = corresponds to the height of 5, 6, or 7 mm The selected trial implant serves as a guide for the two chisels and sets the direction and chisel depth. Ensure the trial implant stop is positioned prior to chiseling. The stop controls posterior advancement of the trial and chisel. Monitor the position of the trial and the chisel cutting under lateral image intensifier control. Open the anterior cortex with the keel cutting chisel and prepare the position of the implant keel. Using the box cutting chisel, prepare the posterior end of the implant keel for insertion of the implant. The depth of the cut made with the keel cutting chisel determines the posterior end of the chisel cut. It is not possible to go deeper with the box cutting chisel. The chisel cut determines the final implant position and is to be checked with the image intensifier. Re-open the vertebral body retainer a little bit before removing the trial implant in order to avoid damage of the end plate when inserting the implant. Synthes 19

21 7 Check keel cut Instruments SFC320R Keel Cut Cleaner Position Gauge see Instruments page 11 SFC506R Shaft for Position Gauge Insert the sharp tip of the keel cut cleaner at the posterior end of one of the keel cuts and pull outwards. Repeat procedure until all bone material is removed. Repeat procedure with second keel cut. Check depth of the keel cut A Using the keel cut cleaner Insert the sharp tip of the keel cut cleaner at the posterior end of one of the keel cuts and check its position under lateral image intensifier control. If possible save this x-ray picture and consult it during insertion of the implant (see step 8, Insert implant ). If desired position is not reached, insert trial implant again and repeat procedure with box cutting chisel (see step 6 B, Chiseling ). 20 Synthes Prodisc-C Technique Guide

22 B Using the position gauges Choose position gauge with the same footprint and same height as the trial implant that was used (same color coding). Screw the shaft to the chosen position gauge. Verify correct size of the footprint Insert position gauge to the very posterior end of the disc space. Check correct posterior position under lateral image intensifier control. Judge the size of the footprint with respect to the vertebral end plates. If in doubt check again with a position gauge of a larger footprint (width or depth). Verify correct depth and parallelness of the keel cut Place the position gauge at the posterior end of the keel cuts. Make sure that the posterior rim of the position gauge reaches the position where the Prodisc-C implant finally should be. The distances of both keels to the posterior walls of the vertebrae must be identical. Check both under lateral image intensifier control. Notes: The position gauge is cannulated; there is a thread for the shaft on one side only. The position gauge has the same outer dimensions as the respective Prodisc-C implant. Just the keels are slightly narrower, in order not to endanger the press fit. Thus the position gauge should nicely fit into the space prepared for the implant. Synthes 21

23 8 Insert implant Instruments SFC61xR* SFC602R SFC825R Spacer for Implant Inserter, radiolucent, height 5, 6 or 7 mm Implant Inserter Mallet * x = corresponds to the height of 5, 6 or 7 mm Spread the distal tips of the implant inserter and install the appropriate sized spacer as determined by the selected implant height. Insert the pre-assembled Prodisc-C implant en bloc with the implant inserter under image intensifier control into the prepared implant bed. Ensure the inferior plate with the PEinlay is caudal. View in the image intensifier The polymeric part of the spacer is not visible in the lateral view of the image intensifier. A small tantalum marker represents the anterior rim of the Prodisc-C implant. Notes: The spacer must not only fit with its metal rod in the inserter but also with the cylindrical part of the polymer. Avoid compression of the posterior elements during implant insertion. Avoid damage to the end plate, as it can increase the risk of implant migration. 22 Synthes Prodisc-C Technique Guide

24 9 Remove instruments Instrument SFC810R Screwdriver The implant inserter can be easily released from the implant and removed by pulling it straight back out of the operative field. Step by step remove the securing nuts, the vertebral body retainer, and the retainer screws. Synthes 23

25 Multi-Level Cases Multi-level Prodisc-C surgeries should be performed level by level. The more symptomatic level should be operated on first. In multi-level cases, there must be sufficient bone between the keels of the prosthesis. If necessary, e.g. with small vertebral bodies, the retainer screws of the vertebral retainer can also be inserted obliquely. The screws in the upper and lower vertebrae should be placed in the upper and lower third of the respective vertebra. The screw in the vertebra in the middle should be placed in line with the others screws, but in the middle of the vertebra. Insert the screws under image intensifier control. If both levels show severe symptomatic degeneration, the discectomy should be performed on both levels at the same time. To stabilize the treated segments a trial implant should be placed into one level while mobilizing and preparing the second level. The second trial is only used as a spacer; it is not important to choose the correct size. The three screws to mount the vertebral body retainer are in place during preparation of the disc space and insertion of the implant. Always position the vertebral body retainer over the segment you are currently working on. 24 Synthes Prodisc-C Technique Guide

26 Cases Examples Case 1: Symptomatic cervical disc disease C5 C7 Patient: Symptoms: Diagnosis: History: Male, 50 years Arm pain Abnormal motor function C7 right (active movement against resistance) Symptomatic cervical disc disease C5 C7 Osteophytes formation C5 C6 and C6 C7 Disc herniation C5 C6 and C6 C7 Radiculopathy C6 C7 Loss of disc height C6 C7 Arm and neck pain for more than 6 weeks Physiotherapy, chiropractic and injection without success Visual analog scale: pre-op 6 months 12 months post-op post-op VAS for neck pain intensity VAS for neck pain frequency VAS for arm pain intensity VAS for arm pain frequency VAS for satisfaction Preoperative Anteroposterior Lateral Flexion Extension MRI lateral 12 months follow up Anteroposterior Lateral Flexion Extension Synthes 25

27 Case 2: Degenerated disc disease C6 C7 Patient: Symptoms: Diagnosis: History: Female, 42 years Frequently arm and neck pain Sensory dysfunctions left Symptomatic cervical disc disease C6 C7 Degenerated disc C5 C6 Disc herniation C5 C6 and C6 C7 Sensory dysfunction C6 C7 Arm and neck pain for more than 6 weeks Visual analog scale: pre-op 6 months 12 months post-op post-op VAS for neck pain intensity VAS for neck pain frequency VAS for arm pain intensity VAS for arm pain frequency VAS for satisfaction Preoperative Anteroposterior Lateral Flexion Extension MRI lateral 12 months follow up Anteroposterior Lateral Flexion Extension 26 Synthes Prodisc-C Technique Guide

28 Bibliography Bertagnoli R, Duggal N, Pickett GE, Wigfield CC, Gill SS, Karga A, Voigt S (2005) Cervical total disc replacement, part two: clinical results. Orthop Clin North Am 36 (3): Bertagnoli R, Yue JJ, Pfeiffer F, Fenk-Mayer A, Lawrence JP, Kershaw T, Nanieva R (2005) Early results after ProDisc-C cervical disc replacement. J Neurosurg Spine 2 (4): DiAngelo DJ, Foley KT, Morrow BR, Schwab JS, Jung Song, German JW, Blair E (2004) In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant. Neurosurg Focus 17 (3): Durbhakula MM, Ghiselli G (2005) Cervical total disc replacement, part I: rationale, biomechanics, and implant types. Orthop Clin North Am 36 (3): Review. Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH (1999) Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am. 81 (4): Hilibrand AS, Robbins M (2004) Adjacent segment degeneration and adjacent segment disease: the consequences of spinal fusion? Spine J 4 (6 Suppl): 190S 194S. Review. Le H, Thontrangan I, Kim DH (2004) Historical review of cervical arthroplasty. Neurosurg Focus 17 (3): 1 9 Panjabi M et al (1991) Cervical Human Vertebrae: Quantitative Three-Dimensional Anatomy of the Middle and Lower Regions.Spine 16 (8): White A, Panjabi M (1990) Clinical BioMechanics of the Spine. J. B. Lippincott Company: Yoganandan N, Kumaresan S, Pintar FA (2001) Biomechanics of the cervical spine Part 2. Cervical spine soft tissue responses and biomechanical modeling. Clin Biomech 16 (1): 1 27 Synthes 27

29 Presented by: SE_ AC Synthes 2007 Prodisc is a trademark of Synthes Subject to modifications