Surgical Technique Manual

Transcription

1 InterFuse S Interbody Fusion System Surgical Technique Manual VERTEBRAL TECHNOLOGIES MS Rev. O

2 Product Overview Introduction The VTI InterFuse S implant is an interbody fusion device that combines the large vertebral endplate contact area characteristic of many ALIF devices with the ability for implantation through a less invasive unilateral posterior lumbar interbody fusion approach. The unique design of the InterFuse S device incorporates an anatomical shape that assures contact with the peripheral margins and the well-vascularized central portion of the vertebral endplate, areas shown to be critical to proper loading and for reduction of subsidence risk. The interlocking design provides the necessary structural support and endplate contact area while the open caudal and cephalad spaces accommodate new bone growth and fusion. The VTI InterFuse S device is made of radiolucent PEEK-OPTIMA to provide structural strength with nearly the same stiffness of cortical bone while maintaining the ability to assess fusion progress radiographically. The VTI InterFuse S device incorporates tantalum markers to aid in visualizing the device during intraoperative and postoperative radiographic assessment. The unique rail-and-slot design assures proper placement and alignment of each module, and the symmetry of the internal segment allows for the use of as few as three to as many as six modules to provide the best fit possible for each individual patient at each disc level. The rail extensions are made of stainless steel (see photo above). The VTI InterFuse S device is available in four heights (8mm, 10mm, 12mm, 14mm) and two endplate angles (parallel, 5º lordotic angle). All devices have a 20mm A-P length. The VTI InterFuse S device is intended for use with supplemental spinal fixation systems, and provides structural anterior column support even in the absence of fusion when used as intended. Indications for Use: Caution: Federal (USA) law restricts this device to sale by or on the order of a physician. The InterFuse S Intervertebral Body Fusion Device is indicated for intervertebral spinal fusion procedures in skeletally mature patients with degenerative disc disease (DDD) at one or two contiguous levels from L2-S1. DDD is defined as discogenic back pain with degeneration of the disc confirmed by patient history and radiographic studies. These patients may also have up to Grade I spondylolisthesis or retrolisthesis at the involved level(s). The InterFuse S device is to be used in patients who have had at least six (6) months of non-operative treatment. These patients may have had a previous non-fusion surgery at the involved spinal level(s). The InterFuse S device is indicated for use with autogenous bone graft, and to be used with supplemental internal spinal fixation systems that have been cleared for use by the FDA in the lumbosacral spine (e.g., posterior pedicle screw and rod systems, anterior plate systems, and anterior screw and rod systems) Vertebral Technologies, Inc. Page 2 of 17

3 InterFuse S Instruments Various instruments are provided to aid in the implantation of the InterFuse S device. Nucleus Probe Device Sizers Module Holder 2012 Vertebral Technologies, Inc. Page 3 of 17

4 Threaded Inserter Tail Removal Tool Positioning Levers Slap Hammer 2012 Vertebral Technologies, Inc. Page 4 of 17

5 Tail Traction Tool Insertion Guard Module Disengagement Tool Surgical Technique Preoperative Planning Preoperative planning is recommended for determining the height and lateral width of the InterFuse S device that will most likely provide the best fit and fill in the patient s disc space. Determine the approximate implant height required for the patient by using sagittal measurements of the intervertebral discs adjacent to the disc being treated on MRI obtained within the previous 6 months. An alternate method is to use digitally-aided lateral radiographs. Select the device height that most closely matches, but does not exceed, the disc height of the adjacent levels. The implant must fit securely between the endplates when the segment is fully distracted. It is essential to use the tallest possible implant, as determined by the preoperative planning, to maximize segmental stability Vertebral Technologies, Inc. Page 5 of 17

6 Next, determine the approximate InterFuse S device width expected to be implanted from the patient s A-P MRI or radiograph. Select the number of InterFuse S modules to be used in order for the InterFuse S device to maximize contact with the peripheral margins of the endplates once assembled in-vivo. Due to variations in radiographic magnification, these measurements provide only an estimate of the ideal implant size. Final device sizing must be performed just prior to implant insertion using the sizing instruments provided. Actual lateral dimension of the InterFuse S device is determined intraoperatively by the ability to insert modules effectively. Patient Positioning The patient is positioned prone on a lumbar frame that promotes suitable exposure and restores sagittal alignment. Use of c-arm intraoperative radiographic equipment is recommended to assure operative site selection, confirm the precise position of the InterFuse S device implant and minimize surgical exposure. Incision and Pedicle Screw Implantation Perform a midline or paramedian incision and identify the anatomical landmarks including the facets, pars interarticularis, laminae, spinous processes, and transverse processes. If a pedicle screw system is intended to be used, placement of the pedicle screws prior to implantation of the InterFuse S device allows for their use in distraction of the disc to temporarily increase the posterior disc height. If a facet screw system is intended to be used, lateral exposure only to the facets is necessary, and may reduce dissection and trauma to the paraspinal muscles. Distraction Parallel distraction of the disc provides easier insertion of the InterFuse S device modules and subsequent movement of the modules across the disc midline. Parallel distraction also aids in ensuring implantation of an InterFuse S device with sufficient height for complete contact with the endplates following removal of distraction. Distraction can be accomplished by patient positioning with appropriate surgical table or by the following methods Vertebral Technologies, Inc. Page 6 of 17

7 Pedicle Distraction Method Distraction can be applied between the heads of inserted pedicle screws. Use a lateral distractor with the appropriate inserts for the specific pedicle system being utilized. This method temporarily opens the posterior disc space and promotes increased exposure for access, decompression and delivery of the implant. Alternatively, lateral distraction can be applied in a similar fashion after rods have been installed in the pedicle screw system, tightening the screws to maintain distraction and allowing the removal of the lateral distractor. After InterFuse S device insertion is complete, some of the tension on the pedicle screw system can be released to put more pressure onto the InterFuse S device to ensure complete contact between the InterFuse S device and the endplates. Spinous Process / Lamina Spreader Method Place a spreader either between the laminae or at the base of the spinous processes of the appropriate levels and apply distraction. This method temporarily opens the posterior disc space and promotes increased exposure for access, decompression and delivery of the implant. Disc Access and Preparation Create a sufficient unilateral window in the lamina to allow instruments and the implant to be inserted parallel to the vertebral endplates and to allow easy insertion of the implant modules. Extending the laminectomy to the medial border of the inferior facet ensures the greatest ability to reach with instruments across the midline of the disc for removal of the contralateral nucleus, and may aid in reducing contact with local nerve tissue. A device sizer can be used to confirm that the size and shape of the lamina window is adequate for delivery of the InterFuse S modules. The access to the disc is made via a box opening through the annulus using a #11 blade. Use of a paddle shaver, box cutter, or similar cutting tool may aid in removal of the cartilage and posterior vertebral lip which might otherwise prevent implantation of the proper height InterFuse S device. Kerrison rongeurs are useful for squaring off the corners of the working channel to ensure the access is rectangular. Completely remove the disc nucleus and endplate cartilage using a mechanical system and/or rongeurs and curettes. A complete nucleus removal, with special attention to removing the disc material contralateral and ipsilateral to the annulus access, will aid in the proper placement of the InterFuse S device. Up- and down-biting rongeurs and angled ring and cup curettes can be particularly useful in reaching across the midline of the disc. The anterior and lateral walls of the annulus must be preserved Vertebral Technologies, Inc. Page 7 of 17

8 Important: Clean the disc space thoroughly by irrigation with sterile saline solution followed by aspiration. Assess nucleus tissue removal using the Nucleus Probe, with tactile feel and/or radiographic image. Warning: Excessive removal of subchondral bone may weaken the vertebral endplate and result in implant subsidence and loss of segmental stability. Care should be taken not to create a bony ledge in the central portion of the disc medial to the access channel. This will impair movement of subsequent modules across the midline. Determination of Implant Size InterFuse S device height and A-P length chosen preoperatively should be confirmed using the Device Sizers supplied. A small mallet can be used to aid insertion of the Device Sizers if needed. Use the Slap Hammer as needed to remove the sizers. Each sizer has the general shape of an InterFuse S module and the sizer set is provided with 8mm, 10mm, 12mm and 14mm heights and 20mm A-P length. Starting with a smaller sizer, insert the sizer completely into the disc space with the surfaces showing the word ENDPLATE contacting the vertebral endplates. Final height selection is determined when the sizer appears to fit securely in the disc space but does not require the use of the Slap Hammer for removal. Bone Graft Placement Autogenous cancellous bone should be packed firmly within each InterFuse S device module prior to insertion into the disc space. Screw the Threaded Inserter into the posterior threaded hole of the module until it is flush with the back of the module, being careful not to over-tighten the Threaded Inserter, especially for the first module. Modules may instead be loaded into the Insertion Guard prior to the packing of autogenous cancellous bone. Placing the module into the Module Holder helps to secure it while packing the module cavity with bone graft. Should there be any significant space remaining in the disc following InterFuse S device implantation, fill the space with autogenous cancellous bone Vertebral Technologies, Inc. Page 8 of 17

9 Implant Insertion Insert the A module into the disc space (utilizing either the Insertion Guard or Threaded Inserter) such that the serrated surfaces contact the vertebral endplates and the curved portion of the module is oriented to the contralateral side of the disc space. The tail of the module should be protruding from the disc space. Move the A module contralaterally as necessary with the Positioning Lever, using the facet joint as a fulcrum if needed. Insertion of the A Module Insert the tail of the A module into the anterior aspect of the slot of the B module. While holding on to the Threaded Inserter, slide the B module along the tail of the A module until it is completely in the disc space and aligned with the A module. Pulling back gently on the tail of the A module will aid in this process. IT IS VERY IMPORTANT THAT THE MODULES BE PARALLEL TO ONE ANOTHER WHEN THE B MODULE ENGAGES THE A MODULE TO PREVENT ACCIDENTAL REMOVAL OF THE TAIL FROM THE A MODULE (See left figure below). The B module will have achieved proper orientation to the A module when the inter-segment snap lock has been felt and /or heard to engage. Laser marks on the shaft of the Inserter or Insertion Guard show when the front of the B module is past the back of the A module. Use of a small mallet on the end of the Threaded Inserter may be helpful to ensure the modules are fully engaged. DO NOT USE A MALLET ON THE THREADED INSERTER OR INSERTION GUARD UNTIL THE FRONT OF THE B MODULE IS PAST THE POSTERIOR END OF THE A MODULE (See center figure below) Vertebral Technologies, Inc. Page 9 of 17

10 Do not use mallet here. Can use mallet here. Proper engagement of modules. Insertion of the B Segment Successful engagement of the two modules should be assessed by comparing the ends of the tails to be sure they are aligned and to examine the junction of the two modules visually or with the Nerve Probe or other small instrument. Once successful engagement is confirmed, unscrew and remove the Threaded Inserter. If using Insertion Guard, wait to remove the Insertion Guard until after tail removal and module movement. Verification of Module Engagement 2012 Vertebral Technologies, Inc. Page 10 of 17

11 Removing the Module Tails The tail of the A module is then removed using the Tail Removal Tool. 1. Slide the Tail Removal Tool over the tail of the A module so the distal tip of the tool is contacting the implanted module. The end of the A module tail should align with the proximal end surface of the Tail Removal Tool. If the tip of the tail does not align with the end of the Tail Removal Tool, re-evaluate the completeness of the engagement of the two modules and reposition them if necessary, and assure the Tail Removal Tool is in full contact with the InterFuse module. 2. Once assured that the Tail Removal Tool is in proper position, twist the Tail Removal Tool onehalf to one complete rotation to remove the tail from the module. Once the tail separates from the module, hold the metal tail end against the flat area of the handle and remove the Tail Removal Tool from the incisi on. Remove the cut tail from the Tail Removal Tool in preparation for use with the next module. Once the tail of module A has been removed, move the combined modules of A and B contralaterally using one of the Positioning Levers in order to make room for insertion of the next module Vertebral Technologies, Inc. Page 11 of 17

12 The remaining modules are attached and inserted into the disc space in the same fashion as the B module, followed by tail removal as described above. Special attention should be focused on ensuring that the C module is properly aligned with the Threaded Inserter when threading it into the module to avoid cross-threading. This may be facilitated by using the Module Holder to hold the C module and aligning the Threaded Inserter parallel to the flat side of the C module. When advancing the C module, ensure the Inserter is kept parallel with the tail of the B module. It may be necessary to remove additional nucleus material from the ipsilateral side of the disc to ensure there is sufficient space to insert and seat the C module. Most patients are expected to require five modules, utilizing two additional B modules and the final C module (an A-B-B-B-C configuration, based on the order they were inserted). For patients with smaller lateral disc dimensions, a total of three or four modules may be appropriate ( A-B-C or A-B- B-C ). For patients with larger lateral disc dimensions, six modules may be appropriate ( A-B-B-B-B- C ). Before opening up additional single B modules take special care to ensure that there is enough room for the additional modules. A-B-C A-B-B-C A-B-B-B-C A-B-B-B-B-C Three Modules Four Modules Five Modules Six Modules Implantation of the InterFuse device is complete when all desired modules have been interlocked, completely inserted, and all module tails have been removed. If a module needs to be removed, engage the Threaded Inserter instrument in the posterior threaded hole in the InterFuse module for removal. Remove in reverse order of installation with only one module being removed at a time. Use of the Slap Hammer may be helpful for module removal. A lateral radiograph can be performed to assure proper placement of the final assembled device. An example of a two-level implantation with five modules at each level is shown below. Note that the junction of each adjacent module has a set of markers the use of five modules results in four junctions, and therefore four sets of markers Vertebral Technologies, Inc. Page 12 of 17

13 After implantation of the InterFuse S device is complete, release the distraction of the disc prior to permanent positioning of the pedicle screw rods, facet screws, or other posterior fixation system in order to assure complete contact of the InterFuse S device with the endplates. The InterFuse S device is intended for use in conjunction with a supplemental internal spinal fixation system, such as a pedicle screw system. Please refer to the surgical technique manual for the specific spinal fixation system utilized. Documentation of the final InterFuse S device position via fluoroscopic imaging or x-ray film is recommended Vertebral Technologies, Inc. Page 13 of 17

14 Module Disengagement Before use of Module Disengagement Tool, make sure a nerve root retractor is in place to protect the exiting nerve rootlet. In the event one module needs to be removed from the adjacent module, slide the Module Disengagement Tool down the length of the Threaded Inserter as shown in the depictions below. Depress the lever to initiate the disengagement while holding the Module Disengagement Tool against the Threaded Inserter to maintain a parallel orientation of the Threaded Inserter to the Module Disengagement Tool. The threaded module can now be removed Vertebral Technologies, Inc. Page 14 of 17

15 Closure and Postoperative Care A routine wound closure is performed following completion of the InterFuse S device implantation. Routine monitoring of the vital signs, and of the hemodynamic and neurologic status of the patient Pain medication NG tubes and/or Foley catheters, if used, are discontinued within hours Diet is restricted to small amounts of liquids until return of bowel function is completed The patient is encouraged to ambulate as soon as possible. The individual surgeon determines activity level for the patient External bracing is to be used per each surgeon's discretion 2012 Vertebral Technologies, Inc. Page 15 of 17

16 Product Information Implants Catalog Number Implant (Height x A-P Length) Catalog Number Implant (Height x A-P Length) mm x 20mm Parallel mm x 20mm 5º Angle mm x 20mm Parallel mm x 20mm 5º Angle mm x 20mm Parallel mm x 20mm 5º Angle mm x 20mm Parallel mm x 20mm 5º Angle B 8mm x 20mm Parallel B 8mm x 20mm 5º Angle B 10mm x 20mm Parallel B 10mm x 20mm 5º Angle B 12mm x 20mm Parallel B 12mm x 20mm 5º Angle B 14mm x 20mm Parallel B 14mm x 20mm 5º Angle Implant Instrument Set Disc Prep Set (Optional) Catalog Number Instrument Device Sizer, 8mm x 20mm Device Sizer, 10mm x 20mm Catalog Number Instrument Long Ring Cone Curette #2 Angled 15 Ring Cone Curette #2 Lateral Angled Device Sizer, 12mm x 20mm Long Curette #2 Angled Device Sizer, 14mm x 20mm Curette #2 Angled Right 9079 Threaded Inserter Curette #2 Angled Left Positioning Lever - Convex /08 Curved Rongeur Positioning Lever Flat Long Curette #2 Reverse Angled 9082 Slap Hammer 9084 Module Holder 9085 Nucleus Probe 9090 Tail Removal Tool Insertion Guard 9116 Tail Traction Tool Module Disengagement Tool 2012 Vertebral Technologies, Inc. Page 16 of 17

17 Please refer to the InterFuse S Interbody Fusion Device package insert for further information on: INDICATIONS FOR USE CONTRAINDICATIONS WARNINGS & PRECAUTIONS INSTRUMENT CLEANING & STERILIZATION Caution: Federal (USA) law restricts this device to sale by or on the order of a physician. The InterFuse S Interbody Fusion Device Surgical Technique is presented to demonstrate the surgical technique utilized by Jesse P. Butler, M.D., Illinois Bone & Joint, Chicago, IL, Paul Asdourian, M.D., Greater Chesapeake Orthopedic Associates, Baltimore, MD, and Neill M. Wright M.D., Washington University School of Medicine, St. Louis, MO. Vertebral Technologies, Inc., as the manufacturer of this device, does not practice medicine and does not recommend this product or any specific surgical technique for use on any specific patient. The surgeon who performs any implant procedure is responsible for determining the appropriate product(s) and utilizing the appropriate technique(s) for said implantation in each specific patient. For further information, contact: Vertebral Technologies, Inc Baker Road, Suite 550 Minnetonka, MN (952) InterFuseS Surgical Technique MS Rev. O Notes: 2012 Vertebral Technologies, Inc. Page 17 of 17