USS II Screws and Hooks

Transcription

1 USS II Screws and Hooks with Dual Opening Handling Manual Original Instruments and Implants of the Association for the Study of Internal Fixation AO/ASIF

2 Table of contents Implants 2 Indications 6 Handling instructions Handling implants with stick 7 Pedicle screw positioning (posterior instrumentation) 8 Vetebral body screw positioning with washer (anterior instrumentation only) Pedicle hook positioning 3 Lamina hook positioning 5 Angled lamina hook positioning 6 Rod contouring 7 Locking implants to rods 8 Introducing rods into dual-opening implants 20 Distraction or compression of two adjacent implants 23 Connecting a rod to an implant with rod connectors 24 Connecting two rods with cross-link connectors 25 Bibliography 27 The system USS II Screws and Hooks with Dual Opening is a further development of the Universal Spine System (USS). Image intensifier control Warning This description is not sufficient for immediate application of the instrumentation. Instruction by a surgeon experienced in handling this instrumentation is highly recommended. SYNTHES

3 Implants All implants are available in titanium alloy (TAN) and stainless steel (SSt). For titanium alloy, the X in the article number must be replaced by a 4, for stainless steel, the X must be replaced by a 2. USS II Pedicle Screws with Dual Opening and Dual Core 4.2 mm (X ) 5.2 mm (X ) 6.2 mm (X ) 7.0 mm (X ) Rounded tip with thread Double thread Dual core USS II Pedicle Hooks Extra-small (X99.36/37 front opening) Small (X99.34/35 front opening) Standard version (X99.278/279 front opening) Dual opening or front opening (when using rod connectors) USS Screws for Pedicle Hooks Lengths mm (X ) Thread diameter 3.2 mm Core diameter 2. mm USS II Lamina Hooks Extra-small (X99.32/33 front opening) Small (X99.270/27 front opening) Medium (X99.272/273 front opening) Large (X99.274/275 front opening) Dual opening or front opening USS II Lamina Hooks, Angled Right (X99.280/282 front opening) Left (X99.28/283 front opening) Dual opening or front opening 2

4 USS II Sleeves For rods 5.0 mm (TAN, dark blue: X99.239) (a) For rods 6.0 mm (TAN, turquoise: X99.292) (b) a b USS II Nut 2-point (X99.294) USS Rods 5.0 mm Rods, hard, lengths mm (TAN, dark blue: ; SSt: ) For fractures and deformities USS Rods 6.0 mm Rods, hard, lengths mm (pure titanium, gold: ; SSt: ) For fractures and deformities Rods, hard, lengths mm (TAN, turquoise: ) For deformities Rods, soft, lengths mm, (pure titanium, gold: ; SST: ) For lumbar spine in case of degenerative diseases USS II Rod Connectors and Toothed Sleeve for Rods 6.0 mm Rod connectors, open, lengths 5 25 mm (X ) Sleeve, toothed (X99.293) Connectors for USS Rods 5.0 mm and 6.0 mm a Extension connector 5.0 mm (X98.364) Extension connector 6.0 mm (X98.65) Extension connector 5.0/6.0 mm (X98.67) b Parallel connector 5.0 mm (X98.59) Parallel connector 6.0 mm (X98.60) Parallel connector 5.0/6.0 mm (X98.62) a b c c Parallel connector 3.5/5.0 mm ( ) Parallel connector 3.5/6.0 mm ( ) SYNTHES 3

5 Fixation Ring for Compression and Distraction For rods 5.0 mm (X98.909) For rods 6.0 mm (X98.90) Cross-Link Connectors Cross-link rod 3.5 mm, lengths mm (X ) For rods 5.0 mm Cross-link clamp for rods 5.0 mm, right (X99.30) Cross-link clamp for rods 5.0 mm, left (X99.3) Cross-link clamp with rod 5.0 mm (X99.306) For rods 6.0 mm Cross-link clamp for rods 6.0 mm, right (X99.320) Cross-link clamp for rods 6.0 mm, left (X99.32) Cross-link clamp with rod 6.0 mm (X99.307) Implants for anterior stabilisation Anterior Vertebral Body Screw 6.2 mm, lengths mm, dual core, core diameter 4.0/3.5 mm (X ) 8.0 mm, lengths mm, dual core, core diameter 5.0/4.3 mm (X ) Washer for Anterior Vertebral Body Screw 6.2 and 8.0 mm Flat, outer diameter 3.0/5.0 mm (X99.403/404) Angled, outer diameter 3.0/5.0 mm (X99.40/402) 4

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7 Indications Spinal deformities (congenital, idiopathic, neuromuscular) Tumours Fractures Degenerative diseases Note: In the USS II system, rods 5.0 and 6.0 mm can be used but with different sleeves (see page 3). Compared to the 6.0 mm rods, the mechanical strength of the 5.0 mm rods is reduced by 50%. 6

8 Handling implants with stick Since the dual-opening screws have exactly the same head as the pedicle, lamina and angled hooks, the following handling instructions apply to pedicle screws, anterior vertebral body screws, and all three kinds of hooks (subsequently referred to as implants). Attach handle to stick Press the knurled release button on the upper end of the Handle ( ) and simultaneously attach the USS Hook and Screwholder with Hexagonal 4.0 mm (388.62), also called stick, to the handle. 2 Pick up implant Connect the dual-opening implant to the stick and handle by rotating the release button on the handle. 3 Release handle from stick Insert the implant. To release the handle from the stick, press the release button on the handle. SYNTHES 7

9 Pedicle screw positioning (posterior instrumentation) Determine entry point and position of pedicle screws a. Thoracic spine The entry point is just below the rim of the upper facet joint (). The screws should be inserted at an angle of 7 0 towards the midline (2) and 0 20 caudally (3) b. Lumbar spine 2 3 The entry point is at the intersection of a vertical line tangential to the lateral border of the superior articular process and the horizontal line bisecting the transverse processes (4). The screws should be inserted at an angle of 5 0 towards the midline at the thoracolumbar junction (5). They should converge by 0 at L2, increasing to 5 at L5 (6) c. Sacrum The entry point for S is located at the intersection of the vertical line tangential to the lateral border of the superior articular process and the horizontal line tangential to its inferior border (7) Insert the screws converging towards the midline (8) so that they aim towards the anterior corner of the promontorium (9). Note: Ensure that laterally exiting pedicle screws do not injure the L5 nerve root. Avoid the S foramen

10 2 Open pedicle and determine screw length Use one of the Pedicle Awls () ( for screws 4.2 mm; for larger screws) to open the cortex of the pedicle to a depth of 0 mm. Continue opening the pedicle using one of the USS Pedicle Probes (2) with markings at 30, 40 and 50 mm Note: Use the Pedicle Probe 2.8 mm ( ) for 4.2 mm screws, the Probe 3.8 mm ( ) for 5.2 and 6.2 mm screws and the Probe 4.8 mm ( ) for 7.0 mm screws and larger. Determine the length of the pedicle screws using the Depth Gauge for Pedicle Screws ( ) Probe pedicle channel Using the Straight Feeler 2.3 mm ( ) or the Curved Feeler 2.3 mm ( ), probe the pedicle screw channel in order to check the walls in respect of perforation. SYNTHES 9

11 4 Insert pedicle screw into pedicle Pick up the pedicle screw as described on page 7. Insert the pedicle screw into the prepared pedicle until the screw head is well seated and one of the openings points towards the rod that is to be subsequently inserted (). To disconnect the stick from the handle, press the release button (2). Note: If using a rod connector, align the screw head such that one of the openings is perpendicular to the rod. 2 0

12 Vertebral body screw positioning with washer (anterior instrumentation only) The vertebral body screws for anterior instrumentation () ( 6.2 and 8.0 mm) have specially large thread flanks providing enhanced pull-out strength compared to standard pedicle screws. 2 3 Flat (2) and angled (3) washers can be used to reinforce the seating of the screws in an end vertebra for anterior stabilisation. The washer distributes the force exerted by the screw to the bone. The angled washers provide a fixed angle with the screw and prevent the screw from stripping. Prepare screw hole and determine screw length Determine the entry point for the screw, preferably at the junction of the pedicle and the vertebral body. Align the Pedicle Awl () ( ) perpendicularly to the contralateral side and prepare the screw hole. Deepen the screw hole using the Pedicle Probe (2) ( 3.8 mm [ ] for screws 6.2 mm; 4.8 mm [ ] for screws 8.0 mm) until it penetrates the contralateral cortex. 2 3 Determine the length of the vertebral body screw using the Depth Gauge ( ) (3). If an angled washer is used, the definitive length of the selected screw should be 5 mm longer than the measured depth in order to make space for the washer. 2 A Insert flat washer and screw Place a flat washer with the convex side facing down onto the concavity of the vertebral body. Pick up a dual-opening vertebral body screw as described on page 7. Insert the screw into the prepared vertebral body until the screw head is well seated. To disconnect the stick from the handle, press the release button on the handle. SYNTHES

13 2 B Insert angled washer and screw Load an angled washer in the inserter ( ) by simultaneously pressing the loading button () and anchor the washer in the bone by gently tapping the inserter (2). Once the washer is firmly seated, remove the inserter by pressing the loading button (3). Pick up a dual-opening pedicle screw as described on page 7. Insert the screw into the prepared vertebral body until the screw head is well seated (4). To disconnect the stick from the handle, press the release button on the handle

14 Pedicle hook positioning The unique feature of the USS pedicle hooks is that they can be securely fixed to the pedicle by a Screw 3.2 mm (X ), ensuring a high pull-out strength comparable with the pull-out strength of a pedicle screw 6.2 mm. 2 Prepare seat for pedicle hook Prepare the pedicle using the USS Feeler (388.50) (). Place the pedicle feeler between the inferior and superior facet joints. Ensure that the feeler is placed in the articular space and not in the bone of the inferior facet. 3 4 mm To facilitate the insertion of the pedicle hook, remove a small portion of the interior facet with an osteotome (2). There are six marks on the pedicle feeler, when the last mark is reached sufficient bone has been removed to accommodate the hook around the pedicle. Check the optimal position of the pedicle feeler by moving it laterally and cranially (3). Do not push medially. 3 Remove the pedicle feeler. 3 2 Position pedicle hook Using the stick, pick up a pedicle hook from the tray, as described on page 7. Note: Use a front-opening hook if a rod connector is needed for connecting the hook with the longitudinal rod. Insert the Hook Positioner for USS II ( ) into the screw hole of the pedicle hook and ease the hook into the previously prepared seat. Check that the pedicle hook is snug around the pedicle by axial loading of the hook positioner and also by pushing laterally. If it does not move, the pedicle hook is correctly placed around the pedicle. Gently tap the hook positioner with a hammer to firmly seat the hook. Remove the hook positioner and the handle. The stick remains attached to the hook. SYNTHES 3

15 3 Drill hole for screw 3.2 mm For secure anchorage of the pedicle hook to the pedicle, a screw 3.2 mm can be inserted through the hole at the back of the hook. Use the three-fluted Drill Bit 2.0 mm (35.90) together with the USS drill sleeve 2.0 and an oscillating drill to drill the screw hole. The drill sleeve consists of two components, the Drill Sleeve (388.58) and the Handle ( ). These two components must be screwed together before use. Note: Do not start the power drill if the bit does not hit bone after passing through the drill sleeve. 4 Determine screw length Remove the drill sleeve and determine the depth with the Depth Gauge (39.060). 5 Insert screw 3.2 mm Pick up an appropriate screw for pedicle hooks using the Holding Sleeve (388.38) and the Hexagonal Screwdriver (34.070) and insert the screw into the previously prepared drill hole. The pedicle hook is now firmly attached to the pedicle. 4

16 Lamina hook positioning Prepare seat for lamina hook The lamina hook can be placed around either the superior or inferior portion of the lamina. Prepare the seat for the lamina hook using a Lamina Feeler ( or ). To ensure good seating of the hook, carefully remove the ligamentum flavum and a small portion of the lamina with a rongeur. Remove the lamina feeler. 2 Position lamina hook Using the stick, pick up an appropriate lamina hook from the tray as described on page 7. Note: Use a front-opening hook if a rod connector is needed. Insert the Hook Positioner for USS II ( ) into the positioning hole of the hook and ease the lamina hook into the previously prepared seat. The inferior part of the lamina hook must fit closely to the lamina. Note: Ensure that the lamina hook does not lie too deep or press upon the spinal cord. Remove the hook positioner and the handle. The stick remains attached to the hook. SYNTHES 5

17 Angled lamina hook positioning Prepare seat for angled lamina hook Remove the soft tissue from the transverse process. Place a Lamina Feeler ( or ) around the transverse process, elevating the soft tissue attachments from the anterior portion of the transverse process. Remove the lamina feeler. 2 Position angled lamina hook Using the stick, pick up an appropriate angled lamina hook from the tray as described on page 7. Note: Use a front-opening hook if a rod connector is needed. Insert the Hook Positioner for USS II ( ) into the positioning hole of the hook and ease the angled lamina hook into the previously prepared seat. Remove the hook positioner and the handle. The stick remains attached to the hook. 6

18 Rod contouring Use the Bending Template for USS Rods (for rods 5.0 mm: /907; for rods 6.0 mm: /880) to determine the proper rod contour and length. Contour the rod using either the Bending Pliers with Rolls for USS Rods () ( ), or the USS Bending Irons (2) ( left, right). Stainless steel rods can also be contoured in situ using bending irons. Note: Once bent, titanium rods should not be bent back again. Do not bend titanium rods more than Note: Hook/screw offset The anatomical contouring may occasionally prevent the perfect alignment of the implants, making it impossible to insert the rod from the same side. The dual opening and the offset (rods 5.0 mm: 7.8 mm; rods 6.0 mm: 8.8 mm) of the pedicle screws and hooks help compensate for this offset and avoid the need to bend the rod. 7,8 or 8,8 mm SYNTHES 7

19 Locking implants to rods The rod is secured with a sleeve and nut. Note: For a rod 5.0 mm use Sleeve X (in TAN dark blue), for a rod 6.0 mm use Sleeve X (in TAN turquoise). 2 Pick up and locate sleeve with sleeve positioner Fit the Sleeve Pusher ( ) to the Sleeve Positioner for USS II (388.6). Pick up a sleeve, ensuring that the shorter leg of the sleeve pusher stands above the narrow-fluted side of the sleeve. Slide the sleeve positioner over the stick and place on the implant. Press down on the sleeve pusher to place the sleeve on the implant/rod (). Retract the sleeve pusher (2), leaving the sleeve on the implant/rod. If the sleeve cannot easily be positioned, gently tap the sleeve pusher to position the sleeve on the implant using the Hook Positioner for USS II ( ) which is placed in the round dent on the handle of the sleeve pusher. 2 Place nut on implant Pick up the nut from the loading station using the Socket Wrench for 2-point nut, with L-Handle ( ). Introduce the Socket Wrench 5.0 mm with T-Handle (388.43) into the socket wrench for 2-point nut and slide together over the stick. The socket wrench 5.0 mm must engage in the hexagon of the stick, which is used to apply countertorque. If the stick has already been removed, insert the Screwdriver 4.0 mm with T-Handle ( ) into the socket wrench for 2-point nut and apply countertorque. 8

20 3 Tighten nut Tighten the nut with the socket wrench for 2-point nut with L-handle. The socket wrench used for applying countertorque is spring-loaded and can be kept under constant pressure by holding of the T-handle with your left hand. To tighten the nut further, lift off the L-handle with your right hand and relocate. Note: When using a rod 6.0 mm, some thread convolutions will remain visible. SYNTHES 9

21 Introducing rods into dual-opening implants Using the rod introduction pliers, the persuader Occasionally, a rod cannot easily be introduced into a dualopening implant because of the distance between the rod and the implant. When using the Rod Introduction Pliers for USS II ( ), the persuader, the dual-opening implants can be lifted and pulled towards the rod. Thereby, the rod and the implant are fixed directly with the sleeve to be used. For a rod 5.0 mm use Sleeve X99.239, for a rod 6.0 mm use Sleeve X Mount sleeve pusher onto persuader Place the Sleeve Pusher ( ) onto the cylinder of the persuader (). Pick up a sleeve from the loading station using the sleeve pusher (2). The handle of the sleeve pusher must be located on the side of the persuader with the arrow. 2 2 Locate persuader on implants Slide the cylinder of the persuader on the stick and the limb of the pliers on the rod. 20

22 3 Attach support for rod introduction pliers The Support for Rod Introduction Pliers (388.65) serves as a locking device when lifting the implants and allows the implants to be rotated. Slide the support for rod introduction pliers over the protruding end of the stick and simultaneously pull the lever (). The forked opening of the support must face upwards. Release the lever so that the fork of the support engages in the hexagon of the stick (2). 2 4 Bring rod towards dual-opening implant Place the Spreader Forceps (388.40) on the stick between the support for rod introduction pliers and the persuader. Slowly open the spreader to bring the implant up towards the rod. When the opening of the implant is opposite the rod, close the persuader to engage the rod. Note: Do not completely close the persuader since this instrument can exert considerable force. If necessary, the catch can be flipped up so that the persuader does not remain in the closed position. Remove the support for rod introduction pliers. Note: Do not apply too much force on the anchorage of the implant otherwise it will tear out of the bone. SYNTHES 2

23 5 Place sleeve over implant and rod Push the sleeve pusher down the cylinder to place the sleeve over the rod and implant (). Retract the sleeve pusher (2), leaving the sleeve on the implant/rod. If the sleeve cannot easily be positioned, gently tap the sleeve pusher to position the sleeve on the implant using the Hook Positioner for USS II ( ) which is placed in the round dent on the handle of the sleeve pusher. 2 6 Attach implant to rod Remove the persuader. Pick up a nut using the socket wrench for 2-point nut (as described on page 8), drop it over the stick and screw loosely onto the implant. 22

24 Distraction or compression of two adjacent implants Distraction or compression with corresponding forceps Once the rod has been introduced and loosely attached to the implant, carry out any distraction or compression. Before tightening the nut of the implant, use the Spreader Forceps (388.40) for distraction or the Compression Forceps ( ) for compression. a. Option Additional use of fixation ring If the two implants are placed too far from each other, use the Fixation Ring (for rods 5.0 mm: X98.909; for rods 6.0 mm: X98.90). Place the small Hexagonal Screwdriver (34.070) with the Holding Sleeve ( ) onto the fixation ring and place it next to the implant. Carry out distraction or compression. The implant-rod connection must be loose during this procedure. Remove the fixation ring and tighten the nut of the implant. b. Option Additional use of holding forceps for rods Instead of using the fixation ring, secure the Holding Forceps (for rods 5.0 mm: ; for rods 6.0 mm: ) next to an implant and carry out the distraction or compression. SYNTHES 23

25 Connecting a rod to an implant with rod connectors Rod connectors can be used to bridge distances between rod and implant in cases where this cannot be achieved with the persuader (as described on page 20). All rod connectors are open and can be applied at any point during the operation. When using rod connectors, front-opening hooks must be used or the pedicle screws rotated through 90. Note: The rod connectors provided in the set can only be used with rods 6.0 mm. Fasten rod connector to rod Position the rod connector on the rod and insert the ribbed part of the rod connector in the hook or the front-opening screw. Tighten the set screw of the rod connector using the small Hexagonal Screwdriver (34.070). 2 Connect rod connector to implant Place the toothed, golden Sleeve (X98.023) and the 2-point Nut (X99.294) onto the implant and tighten the nut using the Socket Wrench for 2-point Nut with L-Handle ( ), applying countertorque using the Socket Wrench 5.0 mm with T-Handle (388.43) mounted on the stick. Note: Only use the toothed sleeve with rod connectors. 24

26 Connecting two rods with cross-link connectors Cross-link connectors are transverse stabilizers linking the two longitudinal rods, which increases the stiffness of the construct. They are recommended for unstable fractures and multisegmental constructs. Assemble cross-link connectors Outside the operating field, push the appropriate length of cross-link rod 3.5 mm (X ) through the two cross-link clamps (). One right (for rods 5.0 mm: X99.30; for rods 6.0 mm: X99.320) and one left (for rods 5.0 mm: X99.3; for rods 6.0 mm: X99.32) clamp (a) or two identical clamps (b) can be used depending on the space available on the rod. Alternative If the distance between the two rods to be connected is less than 30 mm, one of the two cross-link clamps must be replaced by a Cross-Link Clamp with Rod (for rods 5.0 mm: X99.306; for rods 6.0 mm: X99.307) (c). Push the rod section of the cross-link clamp with rod through the second cross-link clamp. a b Do not tighten the set screws yet. c 2 Mount cross-link connector on rods Click the assembled cross-link connector onto the rods (2a), ensuring that the fixation screws for the rod on the clamps (large screws) are completely unscrewed. 2a The cross-link rod 3.5 mm can be angled by up to ±5 (2b). If the cross-link connector cannot be clicked onto the rod, completely loosen the fixation screw for the rod on both cross-link clamps b SYNTHES 25

27 3 Secure cross-link connector First, tighten the fixation screws for the rods on both crosslink clamps using the Screwdriver 4.0 mm with T-Handle ( ) (). Next, tighten both set screws for the cross-link rod 3.5 mm using the small Hexagonal Screwdriver 2.5 mm (34.070) (2). 2 4 Distract cross-link assembly (optional) Loosen one of the set screws with the small hexagonal screwdriver. Place the Holding Forceps ( ) next to the corresponding clamp and use the Spreader Forceps (388.40) to exert distraction. Retighten the set screw. 26

28 Bibliography For a detailed surgical technique for side-opening USS pedicle screws and hooks, which is comparable with the USS II, refer to the chapter Modular Stabilization System: The Universal Spine System, in: Aebi M, Thalgott JS, JK Webb (998) AO ASIF Principles in Spine Surgery, Springer Berlin Heidelberg, 23 ff. Note: The design of the Universal Spine System USS allows the concept of segmental derotation to be used in the correction of scoliosis while still offering the possibility of applying the classical derotation method following the Cotrel- Dubousset (CD) technique. It offers the possibility of segmental correction and realignment of the spine to the sagitally placed rod. SYNTHES 27

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