USS Variable Axis Screw (VAS) System. For posterior fixation of the lumbar spine.

Transcription

1 USS Variable Axis Screw (VAS) System. For posterior fixation of the lumbar spine. Technique Guide Instruments and implants approved by the AO Foundation

2 Table of Contents Introduction USS Variable Axis Screw (VAS) System 2 AO Principles 4 Indications 5 Surgical Technique Prepare Pedicles 6 Insert Screws 7 Insert Rods 8 Place Collars and Nuts 9 Apply Distraction or Compression 10 Tighten Nuts 11 Optional Techniques 14 Product Information Instruments 16 Set List 21 Synthes Spine

3 USS Variable Axis Screw (VAS) System Designed to restore lordosis Variable axis head offers ±25 of angulation for minimal rod contouring Precontoured rods designed to mimic spinal curvature Permits sagittal and lateral screw offset and reduces the need to contour the rod precisely Technique permits posterior compression Provides stable internal fixation Dual core screw design creates rigid fixation by engagement of cortical threads within the pedicle and cancellous threads inside the vertebral body Rounded, blunt screw tip design allows bicortical fixation 2 Synthes Spine USS Variable Axis Screw (VAS) System

4 Provides optimal environment Variable axis head offers ±25 of angulation to provide optimal rod placement and simplify construct assembly Uses atraumatic technique Preassembled head reduces operative time and minimizes trauma to patient Double-lead thread increases speed of screw insertion for 5.2 mm, 6.2 mm, and 7.0 mm screws Synthes Spine 3

5 AO Principles In 1958, the AO formulated four basic principles, which have become the guidelines for internal fixation. 1 They are: Anatomical reduction Stable internal fixation Preservation of blood supply Early, active 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. 2 AO Principles as Applied to the Spine 3 Anatomic alignment Restoration of normal spinal alignment to improve the biomechanics of the spine. Stable internal fixation Stabilization of the spinal segment to promote bony fusion. Preservation of blood supply Creation of an optimal environment for fusion. Early, active mobilization Minimization of damage to the spinal vasculature, dura, and neural elements, which may contribute to pain reduction and improved function for the patient. 1. M.E. Müller, M. Allgöwer, R. Schneider, and H. Willenegger: Manual of Internal Fixation, 3rd Edition. Berlin; Springer-Verlag Ibid. 3. M. Aebi, J.S. Thalgott, and J.K. Webb. AO ASIF Principles in Spine Surgery. Berlin; Springer-Verlag Synthes Spine USS Variable Axis Screw (VAS) System

6 Indications The Synthes USS are non-cervical spinal fixation devices intended for posterior pedicle screw fixation (T1-S2/ilium), posterior hook fixation (T1-L5), or anterolateral fixation (T8-L5). Pedicle screw fixation is limited to skeletally mature patients with the exception of the Small Stature USS, which includes small stature and pediatric patients. These devices are indicated as an adjunct to fusion for all of the following indications: degenerative disc disease (defined as discogenic back pain with degeneration of the disc confirmed by history and radiographic studies), spondylolisthesis, trauma (i.e., fracture or dislocation), deformities or curvatures (i.e., scoliosis, kyphosis, and/or lordosis, Scheuermann s Disease), tumor, stenosis, and failed previous fusion (pseudoarthrosis). When treating patients with Degenerative Disc Disease (DDD), transverse bars are not cleared for use as part of the posterior pedicle screw construct. When used with the 3.5 mm/6.0 mm parallel connectors, the Synthes USS 6.0 mm rod systems can be linked to the CerviFix 3.5 mm Systems. In addition, when used with 3.5 mm/5.0 mm parallel connectors, the Synthes Small Stature USS can be linked to the CerviFix 3.5 mm Systems. When used with the 5.0 mm/6.0 mm parallel connectors, the Synthes Small Stature USS can be linked to the Synthes USS 6.0 mm rod systems. When used with the 5.5 mm/6.0 mm parallel or extension connectors, Synthes USS 5.5 mm rod systems can be linked to the Synthes USS 6.0 mm rod systems. 5.5 mm/5.5 mm parallel or extension connectors can be used to link all Synthes USS 5.5 mm rod systems to one another. 6.0 mm/6.0 mm parallel or extension connectors can be used to link all Synthes USS 6.0 mm rod systems to one another. Rod-to-rod connectors can be used to link all Synthes USS 5.5 mm rod systems to one another. When used with the 3.5 mm/6.0 mm and 4.0 mm/6.0 mm tapered rods, the Synthes USS 6.0 mm rod systems can be linked to the CerviFix 3.5 mm and 4.0 mm Systems, respectively. When used with the 3.5 mm/5.5 mm and 4.0 mm/5.5 mm tapered rods, Synthes USS 5.5 mm rod systems can be linked to the CerviFix 3.5 mm and 4.0 mm Systems, respectively. When used with the 5.5 mm/6.0 mm tapered rods, the Synthes USS 6.0 mm rod systems can be linked to Synthes USS 5.5 mm rod systems. In addition, Synthes USS 6.0 mm rod systems can be interchanged with all USS 6.0 mm rods and transconnectors except Synthes 6.0 mm cobalt-chromium-molybdenum alloy and titanium grade 3 rods, which can only be used with Pangea. Synthes USS 5.5 mm rod systems can be interchanged with all USS 5.5 mm rods and transconnectors. Synthes USS 6.0 mm Rod Systems: USS Side-Opening, USS Dual- Opening, USS VAS variable axis components, USS Fracture, Click X, Click X Monoaxial, Pangea, Pangea Monoaxial, USS Polyaxial, USS Iliosacral, ClampFix 5.5 mm Rod System: Matrix, MIRS 5.0 mm Rod System: USS Small Stature CerviFix 3.5 mm Rod Systems: CerviFix, Axon, Synapse 4.0 mm Rod System: Synapse Contraindications Use of these devices is contraindicated when there is active systemic infection, infection localized to the site of the proposed implantation, or when the patient has demonstrated allergy or foreign body sensitivity to any of the implant materials. Severe osteoporosis may prevent adequate fixation and thus preclude the use of this or any other orthopaedic implant. Conditions that may place excessive stresses on bone and implants, such as severe obesity or degenerative diseases, are relative contraindications. The decision whether to use these devices in patients with such conditions must be made by the physician taking into account the risks versus the benefits to the patient. Use of these implants is relatively contraindicated in patients whose activity, mental capacity, mental illness, alcoholism, drug abuse, occupation, or lifestyle may interfere with their ability to follow postoperative restrictions, thereby placing undue stresses on the implant during bony healing. This could result in a higher risk of implant failure. When treating patients with Degenerative Disc Disease (DDD), transverse bars are not cleared for use as part of the posterior pedicle screw construct. Please refer to package insert (GP2774 or GP0001) for the full list of warnings and precautions. Synthes Spine 5

7 Prepare Pedicles 1 Prepare pedicles Instruments Pedicle Reamer Pedicle Probe, for 7.0 mm, 8.0 mm and 9.0 mm screws or Probe Awl or Awl, for 8.0 mm and 9.0 mm screws Locate pedicles as described in AO ASIF Principles in Spine Surgery. 4 Use the awl to open the cortex of the pedicles to a depth of 10 mm. Continue opening the pedicles using the probe with markings at 30 mm, 40 mm, and 50 mm. Determine the required lengths of the USS variable axis screws. Note: For 8.0 mm or 9.0 mm screws, use the awl for 8.0 mm and 9.0 mm screws and the pedicle probe for 7.0 mm 9.0 mm screws. To ensure mobility of the polyaxial screwhead, insert the tip of the pedicle reamer into the prepared pedicle. Use rotating movement to remove excess bone. Repeat this procedure for each pedicle. 4. Ibid. 6 Synthes Spine USS Variable Axis Screw (VAS) System

8 Insert Screws 2 Insert screws Instruments mm Hexagonal Screwdriver with T-Handle Holding Sleeve, for Screwdriver Hook or Screw Holder or Handle for Hook or Screw Holder Alternative Instruments mm Hexagonal Screwdriver Shaft Ratchet T-Handle, 6 mm hex coupling Insert screws using the 3.0 mm hexagonal screwdriver with T-handle and holding sleeve or the ratchet T-handle, 3.0 mm hexagonal screwdriver shaft and holding sleeve. Remove the selected self-tapping variable axis screw from the screw rack. Insert the screw into the prepared pedicles until the screwheads are well seated. Turn the T-handle counterclockwise one-half turn in order to ensure that the screwhead is fully flexible. Align the side opening on the screwhead to one side to receive the rod. Repeat for each screw. Note: Before inserting the rod, make sure each of the screwheads is mobile. To facilitate collar and nut placement, use the hook or screw holder. Insert one hook or screw holder into each screwhead and tighten in order to guide the collar and nut in Step 4. Alternatively, use the handle for hook and screw holder to insert the hook and screw holder. Note: The knob on the handle can be turned to tighten or loosen the screw on the hook or screw holder, or it can be pressed down to release the hook or screw holder from the handle. Synthes Spine 7

9 Insert Rods 3 Insert rods Instruments Rod Holding Forceps, for 6.0 mm rods Coated Rod Template for 6.0 mm rod, 150 mm Rod Bender, with bend radius adjustment Determine the correct rod contour and length using the coated rod template. The polyaxial mobility of the screw head aids in compensation for a lateral screw offset. Select the appropriate length 6.0 mm titanium rod and, if necessary, bend the rods using the rod bender. Insert the rods into the side-opening polyaxial screwheads using the rod holding forceps. 8 Synthes Spine USS Variable Axis Screw (VAS) System

10 Place Collars and Nuts 4 Place collars and nuts Instrument Socket Wrench with straight handle Load a collar and a nut directly onto a loading post in the tray. Align the socket wrench with straight handle directly over the loading post and press down until the nut and collar are secured in the wrench. Place the loaded wrench over the hook or screw holder and onto the screwhead. Hand-tighten nuts to hold the rod, while allowing some movement for final adjustments. Note: For constructs with more than two screws on each side, start with the medial screwhead. Repeat for all remaining screws. Although the rods are now secured in the side opening, the screwheads remain mobile. Synthes Spine 9

11 Apply Distraction or Compression 5 Apply distraction or compression (optional) Instruments Distraction Forceps, curved Compression Forceps Distraction or compression with variable axis screws is possible only before the nuts have been tightened. To distract, use the distraction forceps and then tighten the nuts as described in Step 6. To achieve compression, use the compression forceps and then tighten the nuts as described in Step Synthes Spine USS Variable Axis Screw (VAS) System

12 Tighten Nuts 6 Tighten nuts Instruments Socket Wrench with L-Handle Nm Torque Wrench Internal Counter Torque Alternative Instruments Socket Wrench with straight handle Hook or Screw Holder Each nut can be tightened using the socket wrench with L-handle. Either the internal counter torque or the socket wrench with straight handle and a hook or screw holder can be used for countertorque. Tightening method using the internal counter torque Insert the internal counter torque into the socket wrench with L-handle. Hold the internal counter torque stationary and turn the socket wrench with L-handle to secure the nut. This reduces the torque on the bone while tightening the nut. Synthes Spine 11

13 Tighten Nuts continued 6 Tighten nuts continued Tightening method using socket wrench with straight handle for countertorque Place the socket wrench with L-handle over the hook or screw holder and insert the socket wrench with straight handle. Hold the socket wrench with straight handle stationary and turn the socket wrench with L-handle to secure the nut. This reduces the torque on the bone while tightening the nut. Note: Any distraction or compression maneuvers must be completed before tightening. 12 Synthes Spine USS Variable Axis Screw (VAS) System

14 The 10 Nm torque wrench must be used for the final construct tightening Before final tightening, check that the rod is properly positioned in the USS VAS screw. Place the 10 Nm torque wrench over the nut. Insert the internal counter torque into the 10 Nm torque wrench. Hold the internal counter torque stationary while turning the 10 Nm torque wrench. The wrench will click at the preset torque of 10 Nm. Synthes Spine 13

15 Optional Techniques Adding transconnectors Instruments Long Small Hexagonal Screwdriver Measuring Template, for Low Profile Transconnectors The low profile transconnector is designed to be used as a construct stabilizer to reduce rotation. Use the measuring template for low profile transconnectors to measure the distance between the two rods. Choose a transconnector of the appropriate length. With the transconnector setscrews loosened, apply it to the rods. Use the long small hexagonal screwdriver to secure the trans con - nector to the rods by tightening the setscrews on each end. Note: For transconnectors with stargrind, tighten the stargrind setscrew to lock the angle between the rods. When using an adjustable length transconnector, adjust the distance between the rods, if desired, by compressing or distracting; then tighten the center setscrew on the rotating shaft using the long small hexagonal screwdriver. Note: If any part of the construct requires further adjustment, all transconnector setscrews must be loosened. After final adjustment, retighten the setscrews. 14 Synthes Spine USS Variable Axis Screw (VAS) System

16 Remobilization Instrument Locking Ring Extractor Remove the nut, collar, and rod from the construct. Prior to remobilization using the locking ring extractor, loosen the pusher by turning the T-handle counterclockwise to the marked thread and move the tube back. Slide the slotted part of the extractor over the cam of the screwhead s locking ring and push the tube down. Slowly turn the T-handle clockwise until resistance is encountered. Continue turning until the screwhead is remobilized. Caution: Further turning of the T-handle will cause removal of the locking ring from the construct. If the locking ring is removed, the variable axis screw must be removed and replaced. Synthes Spine 15

17 Instruments For pedicle preparation Taps for Dual Core Screws mm mm mm mm mm Cannulated Taps for Dual Core Screws mm mm mm mm mm Universal Spinal System Tap Handle Taps for dual core screws penetrate the pedicle prior to screw insertion. They prepare a pathway with the same pitch as the screw and smaller cancellous core diameter Pedicle Reamer Removes excess bone around the pedicle to enable rotation of USS Variable Axis Screw Head Pedicle Probe, for 7.0 mm, 8.0 mm and 9.0 mm screws Used to open the pedicle canal and determine the proper screw length Probe Straight Ball Tip Probe Used to palpate the walls of the pedicle and to determine proper screw length using the depth markings at 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, and 70 mm. 16 Synthes Spine USS Variable Axis Screw (VAS) System

18 Curved Ball Tip Probe Awl Used to perforate the posterior cortex of the pedicle Awl, for 8.0 mm and 9.0 mm screws For screw insertion mm Hexagonal Screwdriver Shaft mm Hexagonal Screwdriver with T-Handle Holding Sleeve, for Screwdriver, for sideopening implants Ratchet T-Handle, 6 mm hex coupling Synthes Spine 17

19 Instruments continued For rod preparation and insertion Rod Holding Forceps, for 6.0 mm rods Used to place the rod into the Variable Axis Screw. Ratchet-locking mechanism ensures a consistent and stable grip on the 6.0 mm rod. Quick release permits one-handed application for easy maneuvering and rod placement Coated Rod Template for 6.0 mm rods, 150 mm Used to determine the length and contour of the rod Rod Pusher, for 6.0 mm rods Assists rod placement into the side-opening implants Rod Bender, with bend radius adjustment Used to contour the rod. Knob is used to adjust the bend radius. For construct assembly Socket Wrench with L-Handle, 11 mm width across flats Used to tighten the nut once it has been loaded onto the implant Socket Wrench with straight handle, 6 mm width across flats Used with Hook or Screw Holder (388.61) for countertorque during tightening. 18 Synthes Spine USS Variable Axis Screw (VAS) System

20 Socket Wrench with straight handle, 11 mm width across flats Used to load the collar and nut directly onto the implant and secure them to the rod. The instrument retains both the collar and nut for ease of construct assembly Nm Torque Wrench, 11 mm width across flats Important: For final tightening of the construct, this wrench must be used to apply the proper amount of torque Counter Torque Sleeve This instrument is used in conjunction with the Hook or Screw Holder to reduce torque on the bone while tightening the nut Internal Counter Torque Used with the 11 mm Hex Socket Wrench to reduce the torque on the bone while tightening the nut Long Small Hexagonal Screwdriver Used to secure transconnector to the rods Hook or Screw Holder Synthes Spine 19

21 Instruments continued Handle for Hook or Screw Holder Facilitates positioning of the USS VAS collar and nut, acting as an extension to the implants Measuring Template, for Low Profile Transconnectors For distraction and compression Distraction Forceps, curved Compression Forceps For extraction Locking Ring Extractor, for USS Variable Axis Screws 20 Synthes Spine USS Variable Axis Screw (VAS) System

22 Universal Spinal System Variable Axis Screw Instrument Set ( ) Graphic Case USS Variable Axis Screw Instrument Set Graphic Case Instruments Taps for Dual Core Screws mm mm mm mm mm Cannulated Taps for Dual Core Screws mm mm mm mm mm mm Hexagonal Screwdriver Shaft mm Hexagonal Screwdriver with T-Handle, 2 ea Socket Wrench with L-Handle, 11 mm width across flats Socket Wrench with straight handle, 6 mm width across flats Socket Wrench with straight handle, 11 mm width across flats, 2 ea Nm Torque Wrench, 11 mm width across flats Counter Torque Sleeve Internal Counter Torque Universal Spinal System Tap Handle Long Small Hexagonal Screwdriver Locking Ring Extractor, for USS Variable Axis Screw Holding Sleeve, for Screwdriver, for side-opening implants, 2 ea Distraction Forceps, curved Compression Forceps Rod Holding Forceps, for 6.0 mm Rods, 2 ea Pedicle Reamer Pedicle Probe, for 7.0 mm, 8.0 mm and 9.0 mm screws Probe Straight Ball Tip Probe Curved Ball Tip Probe Awl Awl, for 8.0 mm and 9.0 mm screws Hook or Screw Holder, 8 ea Handle for Hook or Screw Holder, 2 ea Ratchet T-Handle, 6 mm hex coupling Measuring Template, for Low Profile Transconnectors Coated Rod Template for 6.0 mm rods Rod Pusher, for 6.0 mm rods Rod Bender, with bend radius adjustment Synthes Spine 21

23 Titanium Universal Spinal System Variable Axis Screw Implant Set ( ) Graphic Case Titanium USS Variable Axis Screw Implant Set Graphic Case Implants Titanium Collar, for USS Variable Axis Screws, 16 ea Titanium Nut, 11 mm across flats, 16 ea. Titanium Low Profile Transconnectors mm 34 mm, 2 ea mm 41 mm, 2 ea mm 55 mm, 2 ea mm 83 mm, 2 ea. 6.0 mm Titanium Curved Rod mm, 2 ea mm, 2 ea mm, 4 ea mm, 4 ea mm, 4 ea. 6.0 mm Titanium Soft Rod mm, 4 ea mm, 4 ea mm, 4 ea mm, 4 ea mm, 4 ea. 5.2 mm Titanium USS Variable Axis Screws* mm thread, 2 ea mm thread, 6 ea mm thread, 6 ea mm thread, 4 ea mm thread, 2 ea mm thread, 2 ea. 6.2 mm Titanium USS Variable Axis Screws* mm thread, 2 ea mm thread, 6 ea mm thread, 8 ea mm thread, 8 ea mm thread, 6 ea mm thread, 2 ea mm thread, 2 ea mm thread, 2 ea. *Double lead thread 7.0 mm Titanium USS Variable Axis Screws* mm thread, 2 ea mm thread, 6 ea mm thread, 8 ea mm thread, 8 ea mm thread, 6 ea mm thread, 2 ea mm thread, 2 ea mm thread, 2 ea. 8.0 mm Titanium USS Variable Axis Screws mm thread, 2 ea mm thread, 6 ea mm thread, 8 ea mm thread, 8 ea mm thread, 6 ea mm thread, 2 ea mm thread, 2 ea mm thread, 2 ea. Note: For additional information, please refer to package insert. For detailed cleaning and sterilization instructions, please refer to In Canada, the cleaning and sterilization instructions will be provided with the Loaner shipments. 22 Synthes Spine USS Variable Axis Screw (VAS) System

24 Also Available Implants 4.2 mm Titanium USS Variable Axis Screws* mm thread mm thread mm thread mm thread 5.2 mm Titanium, USS Variable Axis Screw* mm thread 6.2 mm Titanium USS Variable Axis Screw* mm thread 7.0 mm Titanium USS Variable Axis Screws* mm thread mm thread mm thread mm thread mm thread mm thread 8.0 mm Titanium USS Variable Axis Screws mm thread mm thread mm thread mm thread mm thread mm thread 9.0 mm Titanium USS Variable Axis Screws mm thread mm thread mm thread mm thread mm thread mm thread mm thread mm thread mm thread mm thread mm thread mm thread mm thread *Double lead thread Synthes Spine 23

25 Synthes Spine 1302 Wrights Lane East West Chester, PA Telephone: (610) To order: (800) Fax: (610) Synthes (Canada) Ltd Meadowpine Boulevard Mississauga, Ontario L5N 6P9 Telephone: (905) To order: (800) Fax: (905) Synthes, Inc. or its affiliates. All rights reserved. CerviFix and Synthes are trademarks of Synthes, Inc. or its affiliates. Printed in U.S.A. 8/12 J3911-G