Technique Guide. Less Invasive Stabilization System (LISS). Allows percutaneous plate insertion and targeting of screws in the proximal tibia.

Transcription

1 Technique Guide Less Invasive Stabilization System (LISS). Allows percutaneous plate insertion and targeting of screws in the proximal tibia.

2 Table of Contents Introduction Less Invasive Stabilization System (LISS) 2 Indications 5 Clinical Cases 6 Surgical Technique Preoperative Planning 8 Patient Positioning 9 Incision 9 Reduction 10 Instrument Assembly for Insertion 11 Plate Insertion 14 Use of Pull Reduction Instrument 19 Insertion of Locking Screws 21 Postoperative Treatment 25 Troubleshooting 26 Tips 27 Product Information Implants 31 Instruments 32 Set Lists 34 References 37 Image intensifier control Synthes

3 Less Invasive Stabilization System (LISS) Plate osteosynthesis in accordance with AO principles has resulted in improved restoration of full function to the injured limb and mobility to the patient. Infection, refracture, delayed union, loss of reduction, and the need for bone graft are not uncommon, although the majority of fractures heal without complication. These complications may be the result of surgical techniques which impair the normal blood supply to bone and soft tissue (see References, p. 37). Developments such as closed, indirect reduction techniques; implants with minimal bone contact; development of internal fixators; and further advances in the area of extra medullary force carriers have evolved in order to limit soft tissue disruption, preserve the blood supply, and reduce the risk of varus collapse. The Less Invasive Stabilization System (LISS) is an extramedullary, internal fixation system that has been developed to incorporate these technical innovations and surgical techniques. Its main features are an atraumatic insertion technique, minimal bone contact, and a locked, fixed-angle construct. Biomechanics of unicortical, locked screws Traditional compression plating Traditional bone screws in plates have relied on two forces to create stable fixation: compression between opposing cortices and friction between the plate and bone caused by the screw. A tensile force is generated along the axis of the screw. This tensile force relies on the shear strength of the bone at the screw-thread interface. In particularly hard bone, higher forces can be generated, whereas in softer, osteopenic bone, the shear strength is lower and more susceptible to stripping. As the screw is tightened, its increasing tensile force creates increasing compressive force between the plate and bone. This compression generates a friction force between the bone and plate. Applied load is transferred from the bone to the plate, across the fracture, and back to the bone. A tight frictional interface is key to the load transmission. As long as the applied (patient) load is less than the frictional force, the construct will remain stable. Although a bicortical screw has inherent angular stability, when the patient load exceeds the maximum friction available, some collapse across the fracture gap results. This collapse is due to the lack of angular stability between the plate and the screw. 2 Synthes Less Invasive Stabilization System (LISS) Technique Guide

4 Locked screw-plate constructs Traditional unicortical bone screws have lower load carrying capability than bicortical screws. If a unicortical screw is locked to the plate, its load carrying capacity increases due to the angular stability. This locked screw-plate connection is the path for load transmission to the plate. Both a locked screw and a conventional screw are subjected to the same patient load. However, load on the bicortical, non-locked screw is higher, due to the initial tightening required to generate friction between the plate and the bone, to ensure construct stability. In conventional plating, even though the bone fragments are correctly reduced prior to plate application, if the plate does not fit the bone, the result will be fracture displacement. If a locked internal fixator is applied to a reduced long bone fracture, the alignment is maintained by the locked screw construct. A locked internal fixator functions as a splint, which relies on relative stability for secondary healing and callus formation. However, this implant does not inherently reduce or align the fracture during its placement (as with a nail). The implant locks the bone segments in their relative positions regardless of how they are reduced. Preshaping the plate minimizes the gap between the plate and the bone, but an exact fit is not necessary for implant stability. A conventional plate must be tightened against the bone in order to generate the frictional forces needed for stability. This compresses the periosteum between the plate and the bone and theoretically compromises blood flow in the area of plate contact. With a locked internal fixator, the plate is not compressed against the bone, thus reducing or avoiding constriction of the local blood supply. Percutaneous, submuscular insertion of the plate does not disrupt the cortical blood supply. LISS offers the locking internal fixator construct for use in the proximal tibia. In addition, the availability of an aiming guide allows for percutaneous targeting of screws through stab incisions. The aiming guide also ensures that all screws will be properly inserted and locked to the plate. Fixed-angle screws extending into the medial fragment avoids the need for additional implants to buttress a medial split. The anatomic shape of the plate and a locked construct eliminate the need for intraoperative contouring. Synthes 3

5 Less Invasive Stabilization System (LISS) continued Traditional plating and locked internal fixators comparison Traditional plating Screws tighten plate to bone to generate compression Screw threads in bone are under a load applied intraoperatively Patient loads (weight and movement) add to the amount of preload on the bone/plate/screw construct Locked internal fixators Screws lock to the plate Screws inserted into bone with minimal axial preload No stress in the system (bone or plate) prior to patient loads Features Drill Thread Tap Locking thread Unicortical locking screws offer angular stability for optimal purchase and reduced stress on the bone. 5.0 mm locking screws drill, tap and thread into bone as well as threading into the plate to lock. Optimized screw position to place metaphyseal screw in the dense peripheral bone of the plateau. 4 Synthes Less Invasive Stabilization System (LISS) Technique Guide

6 Indications For fixation of fractures in the proximal tibia: Extra-articular fractures Complete intra-articular fractures including those with associated coronal fractures Proximal shaft fractures Synthes 5

7 Clinical Cases Case 1 Articular fracture Female, 44 years old, AO Classification 41-C3. Patient underwent provisional spanning external fixator on date of injury. Definitive fixation occurred nine days post-trauma. Preoperative AP Preoperative lateral Preoperative AP with spanning external fixator and knee in traction Preoperative lateral with spanning external fixator and knee in traction Five-month postoperative AP. Patient began full weight bearing at three months. Five-month postoperative lateral. Note posterior metaphyseal consolidation. 6 Synthes Less Invasive Stabilization System (LISS) Technique Guide

8 Case 2 Proximal third shaft fracture Female, 59 years old, AO Classifica tion 42-A2 with an associated ankle fracture/dislocation. Patient has insulin dependent diabetes mellitus. Preoperative AP Preoperative lateral Three-month postoperative AP. Patient began full weight bearing at this point. Three-month postoperative lateral demonstrates significant posterior consolidation. Synthes 7

9 10/00 GP1606A J3343A Preoperative Planning Use the AO Preoperative Planning Template to determine the length of the plate and position of the screws. Screw length may also be determined with K-wires. In general, LISS plate length and screw position are selected similarly to external fixation determinations; close to and away from the fracture. At least four (4) screws should be placed in the intact shaft distal to the fracture. The selected LISS plate should be longer than a traditional plate. Titanium Proximal Tibia LISS Plates for Left Tibia D E A C B AP View AP View Titanium Proximal Tibia LISS Plates (this view for left tibia) [422.30x series] Note: Plates for right tibia on other side AO ASIF Titanium Screw Hole Insert, 5 mm mm Titanium Locking Screw, 18 mm mm Titanium Locking Screw, 26 mm mm Titanium Locking Screw, 40 mm mm Titanium Locking Screw, 55 mm mm Titanium Locking Screw, 65 mm mm Titanium Locking Screw, 75 mm mm Titanium Locking Screw, 85 mm Screw length recommendations Shaft screws 18 mm or 26 mm locking screws Hole A 40 mm screw places screw tip level with the top of the plate. 26 mm screw places the tip at the level of the D and E screws D Lateral View 5 holes 9 holes 13 holes 140 mm 220 mm 300 mm E A C B Illustrations actual size (0% magnification) mm For use only with the Original AO ASIF System of Instruments and Implants. ASIF is a registered trademark of SYNTHES (USA) and SYNTHES AG Chur. Hole C 75 mm screw places screw tip level with the top of the plate. 55 mm screw places the tip just below the level of the D and E screws. Screw hole inserts Instruments Proximal Tibia LISS Insertion Guide, left or Proximal Tibia LISS Insertion Guide, right Stopper, for LISS Insertion Guides Insertion Sleeve The preoperative planning template is also used to determine which plate holes will be located at the fracture site. To prevent tissue in-growth and facilitate implant removal, 5.0 mm titanium screw hole inserts may be used to fill plate holes that will not be used. Screw hole inserts should be placed prior to plate insertion and the corresponding insertion guide holes marked with stoppers. If a screw must replace a screw hole insert intra operatively, the insert can easily be removed through an insertion sleeve. 8 Synthes Less Invasive Stabilization System (LISS) Technique Guide

10 Patient Positioning and Incision Place the patient in the supine position on a radiolucent table. Support the knee while allowing the leg to move freely. A bump under the patient s buttock brings the patella directly anterior to facilitate true AP and lateral intraoperative images. Use a sterile tourniquet on the injured leg, if desired. Lateral incision A lateral curved (hockey stick) or straight incision is recommended. The skin incision starts at Gerdy s tubercle and extends approximately 50 mm in a distal direction. In cases of complex articular fractures, the incision may extend more proximally than represented. Retract the anterior tibialis muscle approximately 30 mm distally, starting approximately 5 mm from the tibial ridge. Note: If it is determined that a closed insertion procedure is not appropriate, the LISS plate may be applied in an open procedure. This technique may also be used when reduction cannot otherwise be achieved. Synthes 9

11 Reduction Reduction Articular fracture reduction must be complete prior to the placement of the LISS plate. Lag screws are used to reduce the articular surface. The lag screw placement should take into account the preoperative plan for the LISS plate and locking screw locations. Possible sites of lag screw fixation indicated in gray. Before locking screws are placed in each main fragment, length, rotation, varus-valgus and recurvatum correction should be achieved. Extra-articular reduction is accomplished by indirect means (examples: external fixator, distractor, traction, joysticks, bumps, etc.). The metaphyseal/diaphyseal component of the fracture can be aligned by manual traction, a knee-bridging fixator, or a distractor. (The use of two Schanz screws will prevent fragment rotation.) The pull reduction instrument ( ) is available to aid in minor varus-valgus and translation corrections prior to screw placement. (See Use of Pull Reduction Instrument. ) Perform reduction under C-arm guidance and assess in both the AP and lateral views. It is important to verify that the plate is applied on the proximal tibia in the appropriate lateral position. Note: Plate placement which is too posteriorly or anteriorly rotated can cause the screw in hole D to exit the plateau in the proximity of the peroneal nerve and popliteal artery. (See page 28 for optimum plate placement) An external fixator can serve as preliminary fixation. This will not only help maintain reduction or length prior to surgery, but can aid in operative reduction. Example of a possible external fixator frame to facilitate reduction of length, rotation, recurvatum and varus-valgus. 10 Synthes Less Invasive Stabilization System (LISS) Technique Guide

12 Instrument Assembly for Insertion 1 Assemble insertion guide Instruments Proximal Tibia LISS Insertion Guide, left or Proximal Tibia LISS Insertion Guide, right Radiolucent extension Assemble the two parts of the left or right insertion guide: the main component and the radiolucent extension. Main component 2 Insert fixation bolt Instrument Fixation Bolt Insert the fixation bolt through hole A of the insertion guide, ensuring that the knurled nut on the fixation bolt is against the head of the bolt. Note: Letters (A E) are used to identify proximal plate holes and numbers (1 13) are used to identify diaphyseal plate holes. Synthes 11

13 Instrument Assembly for Insertion continued 3 Align insertion guide Align the three points of the insertion guide with the corresponding three points on the plate. 4 Screw fixation bolt to plate Instruments mm Pin Wrench Fixation Bolt Screw the fixation bolt into the LISS plate using the top segment of the bolt. Final tightening is completed with a quarter turn of the pin wrench. 12 Synthes Less Invasive Stabilization System (LISS) Technique Guide

14 5 Screw nut Instruments mm Pin Wrench Insertion Sleeve Stabilization Bolt Screw the nut on the fixation bolt toward the insertion guide to stabilize the attachment between the guide and the LISS plate. Final tightening is completed with a quarter turn of the pin wrench. Note: If desired, insert a stabilization bolt with the insertion sleeve into hole B or C for a more stable attachment of the plate to the insertion guide. This offers greater stability if there is resistance from soft tissue or fracture fragments during insertion. Synthes 13

15 Plate Insertion 1 Insert plate Insert the plate between the anterior tibialis muscle and the periosteum, under fluoroscopic control. Keep the distal end of the plate in constant contact with the bone during insertion. Place the proximal end of the plate against the lateral plateau. Note: It is recommended that the plate be inserted with the distal tip sliding along the tibial crest. This allows for visual clues or palpation of the plate s progress. It also prevents migration of the plate posterior into neurovascular structures. 2 Adjust plate position To find proximal-distal plate placement, slide the plate distal and then proximal. Tactile feedback will indicate proper plate placement on the flare of the lateral plateau. 14 Synthes Less Invasive Stabilization System (LISS) Technique Guide

16 3 Insert K-wire Instrument mm Kirschner Wire, with threaded spade point tip, 280 mm Insert a 2.0 mm Kirschner wire through the K-wire hole proximal to holes D and E to provide preliminary fixation of the plate. The K-wire will be approximately parallel to the plateau. Note: Alternatively, or in addition, a K-wire may be placed through the fixation bolt for preliminary plate fixation. 4 Confirm plate position Confirm proper position of the distal end of the plate with a lateral C-arm view. The diaphyseal screws must be positioned through the center of the intramedullary canal; therefore, in a lateral view the distal end of the plate should be centered on the shaft. Synthes 15

17 Plate Insertion continued 5 Make incision at distal hole Instruments Insertion Sleeve mm Trocar Mark the most distal hole using the insertion sleeve with the 5.0 mm trocar in hole 5, 9, or 13 and make an incision. A slightly elongated distal incision is useful to both check plate location and avoid damage to the superficial peroneal nerve. The nerve crosses the tibia in the proximity of the distal part of the 13-hole plate. This extended incision is recommended to visualize the nerve. 16 Synthes Less Invasive Stabilization System (LISS) Technique Guide

18 6 Replace insertion sleeve and trocar Replace the insertion sleeve and trocar through the stab incision. Ensure that the insertion sleeve is fully seated in the guide, to avoid interposed soft tissue, which can keep the bolt from engaging with the plate. Secure the sleeve by tightening the nut on the side of the guide. 7 Remove trocar; insert stabilization bolt Instruments mm Pin Wrench Stabilization Bolt Remove the trocar and close the plate insertion frame by threading the stabilization bolt into the distal plate hole. Final tightening of the stabilization bolt is completed with a quarter turn of the pin wrench. 8 Insert K-wire through stabilization bolt Instrument mm Kirschner Wire Insert the 2.0 mm K-wire through the stabilization bolt. Check the position of the plate and reduction. Complete reduction and confirm the plate position prior to placing locking screws. Note: If a supplementary stabilization bolt was inserted in a proximal hole, it may now be removed. The insertion sleeve has a square pattern where it mates with the hole in the insertion guide. This must be fully seated to allow the stabilization bolt to thread into the plate. Synthes 17

19 Plate Insertion continued 9 Reconfirm plate placement Instruments Insertion Sleeve mm Kirschner Wire Insertion Sleeve Slight variations in plate placement can cause the screw in hole D to exit the plateau in the proximity of the peroneal nerve and popliteal artery. To avoid this, it is important to check the plate position again before the locking screws or the pull reduction instrument are inserted. Place the insertion sleeve and 2.0 mm K-wire insertion sleeve in hole D. Insert a 2.0 mm K-wire. Using a lateral C-arm view, confirm that the wire does not exit the plateau posteriorly. If the K-wire exits the plateau posteriorly, the plate should be repositioned or a shorter screw than originally planned should be used. 18 Synthes Less Invasive Stabilization System (LISS) Technique Guide

20 Use of Pull Reduction Instrument Instruments Insertion Sleeve mm Trocar Pull Reduction Instrument Additional varus-valgus correction can be completed prior to placement of locking screws in both main fracture fragments. The pull reduction instrument with quick coupling is placed through guide and plate holes to pull or push the bone fragments in relation to the plate. This instrument can be used for: Minor varus-valgus adjustment (approximately 2 4 ) Translational adjustments Stabilization of plate-bone orientation during insertion of the first screws Alignment of segmental fragments Predrilling dense or thick cortical bone before placement of a 5.0 mm locking screw to prevent the screw drilling flutes from filling before the screw is fully inserted. (For options in dealing with dense or thick cortices, see page 30.) Three insertion sleeves are included in the set. The stabilization bolt must be used with an insertion sleeve, and one must be reserved for locking screw insertion. If more than one pull reduction instrument is used, insert the reduction instrument without the nut attached. The sleeve can be removed for use elsewhere, and the nut replaced to tighten against the guide. 1 Make a stab incision Place the insertion sleeve and trocar in the insertion guide. Mark the location with a skin impression. Remove the sleeve and trocar to create a stab incision. 2 Reinsert sleeve with trocar Reinsert the sleeve with the trocar until it is fully seated, to ensure that no soft tissue is interposed. Remove the trocar. Synthes 19

21 Use of Pull Reduction Instrument continued 3 Insert pull reduction instrument Instrument Pull Reduction Instrument With the pull reduction instrument attached to a power tool (quick coupling), place it in the desired position through the sleeve. (Use the irrigation method described on page 29, Irrigation and cooling ). With the nut in the highest position possible, begin power insertion of the pull reduction instrument. Stop insertion before the end of the threaded portion meets the plate surface. Attempting to advance beyond this point may cause the screw threads to strip in the bone. 4 Reduce fracture Remove the power tool and begin tightening the nut toward the sleeve (or guide) while monitoring progress under C-arm. Stop when the desired reduction is achieved. Note: The diameter of the pull reduction instrument is 4.0 mm, to allow later placement of a 5.0 mm locking screw in the same hole. 20 Synthes Less Invasive Stabilization System (LISS) Technique Guide

22 Insertion of Locking Screws Instruments mm Kirschner Wire Measuring Device mm Kirschner Wire Insertion Sleeve Proper screw placement depends upon fracture type. Choose screw sites in accordance with biomechanical principles for external fixation: screws should be placed close to and away from the fracture. A minimum of four (4) screws is recommended in each main fracture fragment. More screws may be appropriate in osteopenic bone Insert self-drilling 5.0 mm titanium locking screws ( ) proximally, recheck reduction, and then place distal screws. After final fracture alignment is confirmed, insert the remaining locking screws as planned. Note: Due to the close proximity of holes D and E in the insertion guide, insertion sleeves cannot be placed in both holes at the same time. Proximal screws Proximal screw lengths (alpha screws) can be determined through preoperative planning and/or measurement from a K-wire. The 2.0 mm Kirschner wire should be inserted through the 2.0 mm K-wire insertion sleeve and measured with the 2.0 mm K-wire measuring device for LISS. The selected screw length should place the screw drill tip at least 5 mm short of the medial cortex to ensure that it will not protrude. Diaphyseal screws Proper plate placement is important to ensure that diaphyseal screws are centered on the intramedullary canal and engage in the bone. For diaphyseal screw insertion, it may be necessary to use the pull reduction instrument to maintain plate-bone distance (see page 19). In dense or thick cortical bone, drilling action of the initial screw may push the bone away from the plate. Measurement with a K-wire of hole D is recommended as the first step in screw insertion. Placement of the wire in this position not only provides screw length but also feedback on proper plate placement. Use this wire to ensure that a screw in hole D will not exit the tibial plateau near the popliteal artery and peroneal nerve. Synthes 21

23 Insertion of Locking Screws continued 1 Make a stab incision Instruments mm Trocar mm Kirschner Wire Measuring Device mm Kirschner Wire Insertion Sleeve Place the insertion sleeve and trocar into the insertion guide. Mark the location with a skin impression. Remove the sleeve and trocar to create a stab incision. 2 Reinsert sleeve with trocar Reinsert the sleeve with the trocar to ensure there will be no soft tissue interposed between the locking screw and the plate hole. Remove the trocar. 3 Insert locking screw Instrument mm Hexagonal Screwdriver Shaft, self-retaining Attach the selected screw to the 3.5 mm hexagonal screwdriver shaft until it snaps securely in place. Use high-speed power and limited axial pressure to insert a 5.0 mm locking screw. Use irrigation throughout the drilling process (see page 29). Note: If the screwdriver shaft is difficult to remove, see page 26. The shoulder of the hexagonal screwdriver shaft indicates the distance of the screwhead from the plate. Stop power insertion before the screw locks to the plate Synthes Less Invasive Stabilization System (LISS) Technique Guide

24 4 Final tightening Instruments * Large Hexagonal Screwdriver, long or * Hexagonal Screwdriver mm Torque Limiting Screwdriver, self retaining For final tightening, use the torque limiting screwdriver to ensure the torque applied reaches the minimum level necessary for locking. Screwheads should be flush with the plate surface. Note: In some instances, the bone density or interposed soft tissue provides greater resistance to screw insertion than is normally expected. In order to ensure the screwhead is flush with the plate and the screw is locked, additional tightening may be performed using a large hexagonal screwdriver. 5 Mark screw location Instrument Stopper, for LISS Insertion Guides Mark each screw location in the guide using a stopper for reference as screw insertion proceeds. * Also available Synthes 23

25 Insertion of Locking Screws continued Insertion of screws at locations of fixation or stabilization bolt Instrument Stabilization Bolt If preoperative planning determined that the distal end hole or hole A requires a locking screw, follow the instructions below. These steps ensure that the insertion guide remains aligned with the LISS plate for final screw insertion. When used, hole A must always be the last hole filled by a locking screw. Screw placed in hole A (always inserted last) The fixation bolt is the most important connection in stabilizing the insertion guide and the plate. Once the bolt has been removed, it is difficult to reattach the handle to the plate. To avoid losing the orientation between plate and guide, insert this screw last. Before removing the fixation bolt, place at least one stabilization bolt with an insertion sleeve in an adjacent hole. Remove the K-wire and fixation bolt. Place the insertion sleeve and then the locking screw. It is also possible to insert this screw freehand, but only insertion through the handle ensures that the screw and plate are aligned to provide a locked construct. If a locking screw is not planned for hole A, it is recommended that a titanium screw hole insert be used. This ensures that the guide can be reattached to aid in later implant removal. Screw placed in most distal hole The stabilization bolt is used in the distal hole to stabilize the insertion guide and plate. Removal of the stabilization bolt disrupts orientation with the remaining plate holes; therefore this should be the last screw placed in the diaphysis. To insert the screw, remove the K-wire and then the stabilization bolt, with the insertion sleeve remaining. Without applying pressure to the insertion guide, insert a 5.0 mm locking screw. (For 9- or 13-hole plates, the stabilization bolt and insertion sleeve may be placed in holes 5 and 9 to stabilize the frame, if these holes are free of screws.) 24 Synthes Less Invasive Stabilization System (LISS) Technique Guide

26 Postoperative Treatment Postoperative treatment with LISS does not differ from conventional internal fixation procedures. Range of motion of the knee joint and partial weight bearing to at least 10 kg is appropriate. Restrictions may be appropriate in special cases. The presence of callus formation on x-ray indicates indirect or secondary bone healing. Implant removal Instruments * Large Hexagonal Screwdriver or * Hexagonal Screwdriver mm Pin Wrench Proximal Tibia LISS Insertion Guide, left Proximal Tibia LISS Insertion Guide, right Fixation Bolt mm Torque Limiting Screwdriver, self-retaining * Cleaning Instrument Remove the implant only after complete consolidation of the fracture and remodeling of the medullary canal. Remove the implant in reverse order to implantation. First make the incision to fit the insertion guide. Make stab incisions and use the torque limiting hexagonal screwdriver to remove the screws by hand (any long hexagonal screwdriver can be used through the sleeves, but they lack the self-retaining mechanism to aid in screw removal through a stab incision.) After removal of all the screws, remove the plate. If the plate is not easily removed after removal of all the screws, remove the insertion guide, and use only the fixation bolt for the subsequent loosening of the plate. Loosen the plate by applying reciprocating movements to the fixation bolt. Note: Use the additionally available cleaning instrument, as necessary, to remove tissue from the hexagonal socket of the screwhead to facilitate removal. * Also available Synthes 25

27 Troubleshooting Instruments * Large Hexagonal Screwdriver or * Hexagonal Screwdriver mm Torque Limiting Screwdriver, self-retaining Optional instrument T-Handle, with quick coupling If the screwhead is not flush with the plate: The screw may not be fully locked. Use the 3.5 mm torque limiting screwdriver, turning until it clicks. Soft tissue may be interposed between the plate and screwhead. If the screwhead is not flush after use of the torque limiting screwdriver, use a large hexagonal screwdriver to complete tightening. To help avoid this problem, use the trocar prior to screw insertion. If the power screwdriver jams in the screwhead at insertion, the driver may be off center in the sleeve: Release the quick coupling from the driver and loosen or remove the drill sleeve, or Back up the screw slightly and perform final tightening by hand with the torque limiting screwdriver, or If other options do not work, attach the T-handle with quick coupling to pull the screwdriver out. If the locking screw is difficult to insert or stops advancing prior to locking to the plate: The screw should be removed and the flutes cleaned with a K-wire. The screw can be reused if its hexagonal socket is undamaged. This condition may be caused by unusually dense or thick cortical bone (see page 30). 26 Synthes Less Invasive Stabilization System (LISS) Technique Guide

28 Tips Reduction and fixation Instrument Pull Reduction Instrument To avoid interfering with the placement of the LISS plate on the lateral side, lag screws can be placed percutaneously from the medial side. Bumps made of 8, 10, 12, or 15 towels can be used under the knee to help reduce the fracture in the lateral view. Small adjustments in these bumps can make marked changes in the reduction. Varus-valgus can be checked using the C-arm, intraoperative long cassette x-rays or a cautery cord from the femoral head to the center of the ankle joint on an AP view. Use the C-arm at the knee to check that the cord passes 10 mm medial to the center of the knee joint. Adjustment to varus-valgus reduction can be performed with the pull reduction instrument prior to locking screw placement in the malaligned fragment, or with manual pressure on the insertion guide opposed by pressure on the medial aspect of the proximal tibia. A distractor or large external fixator is a useful tool in gaining length reduction. Two distractors may also be used to gain reduction. One is applied medially and the second anterolaterally to minimize malreduction due to uneven distraction. Fractures not treated acutely should be placed in a spanning external fixator to maintain length until LISS fixation can be performed. This frame can also be used intraoperatively to assist fracture reduction. Plate contouring Bending and twisting of the LISS plate is not recommended as this results in misalignment of the insertion guide with the corresponding plate holes. This will make locking screws to the plate difficult or impossible. The fixator s stability is not dependent on the plate matching the contour of the bone exactly, as in standard compression plating. Synthes 27

29 Tips continued Plate placement It may be necessary to increase the incision if soft tissue is impeding proper plate placement. If the plate s position on the tibial shaft is too anterior or posterior, the screws may not be centered on the bone. Malposition of the plate on the dyaphysis may not provide stable fixation. If the plate is placed too posterior or anterior in the plateau, the screw in hole D may exit the plateau in the area of the peroneal nerve and popliteal artery. Correct plate placement Drill Tap Screw locks plate to bone Incorrect plate placement To ensure proper plate placement, these techniques may be used: Direct palpation through a slightly elongated distal incision can be used to confirm the position of the distal end of the plate. This larger incision is also recommended to check the location of delicate neurovascular structures. The holes of the insertion guide may be aligned with the plate holes under C-arm ( bulls-eye ) to confirm central location of the plate on the tibial shaft. The proximal end of the plate tends to lie approximately cm anterior to the anterior aspect of the fibular head. The anterior-proximal aspect of the plate is then approximately 1 cm posterior to Gerdy s tubercle. To check the position of the most proximal screws, holes D and E, place a K-wire in the hole just proximal to holes D and E. This proximal K-wire hole is angled to approximate the angle of the joint surface. The wire is also within one or two degrees of the angle of holes D and E. Drill Threads strip and do not tap Screw locks to plate but has inadequate purchase in bone Correct plate and screw placement Incorrect plate and screw placement 28 Synthes Less Invasive Stabilization System (LISS) Technique Guide

30 Irrigation and cooling The LISS insertion sleeve has a side port to allow for irrigation. This is useful in cooling self-drilling, locking screws or the pull reduction instrument during drilling. It is important to prevent thermal necrosis during the drilling step. Use standard IV tubing and a 60 cc syringe filled with sterile, physiologic, saline solution. Attach the Luer lock to the syringe and cut the opposite end of the tubing. Slide the cut end of the tubing onto the port of the insertion sleeve. Synthes 29

31 Tips continued Screw insertion Instruments mm Hexagonal Screwdriver Shaft, self-retaining mm Torque Limiting Screwdriver, self-retaining Implant removal Instruments Proximal Tibia LISS Insertion Guide, left Proximal Tibia LISS Insertion Guide, right * Cleaning Instrument Use power tools for screw insertion to ensure adequate performance of the self-drilling screw tip. The ease with which the screws advance into the bone will depend on several factors such as bone density and power output of the tools. The screws should be advanced into the bone until the screwhead locks in the plate. The screw s drilling tip has been dimensioned according to an average cortex thickness. If during preoperative planning, it is determined that the cortex is 7 mm thick or more, predrill the cortex using the pull reduction instrument, which is 4.0 mm in diameter. If a standard locking screw is inserted and the drill tip flutes fill with bone chips, the screw will stop advancing. In this case, the screw should be removed and the flutes cleaned with a K-wire. The screw can be reused if its hexagonal socket is undamaged. Both the screwdriver shaft and the torque limiting screwdriver are equipped with a self-retaining mechanism. Slight pressure should be used to ensure that the screwdriver shaft penetrates the socket of the screwhead on pick-up. This retaining feature is key during a closed implant insertion. If necessary, bicortical 4.5 mm cortex screws may be used through the plate. These screws should be used prior to placement of any locking screws in that fracture fragment. If the cleaning instrument is used during implant removal, it should be used through the insertion guide. Inspect the cleaning instrument after every use. Note: Heads will be prominent. Should a screw be removed and reinserted, it is recommended to reinsert by hand using the torque limiting screwdriver to ensure the screw follows the previously established thread path. * Also available 30 Synthes Less Invasive Stabilization System (LISS) Technique Guide

32 Implants Titanium Proximal Tibia LISS Plates, right Holes Length (mm) Titanium Proximal Tibia LISS Plates, left Holes Length (mm) mm Titanium Locking Screws, self-drilling Length (mm) mm Titanium Locking Screws, self-tapping Length (mm) * * 18 Titanium Screw Hole Insert Length (mm) * Also available Synthes 31

33 Instruments mm Kirschner Wire, with threaded spade point tip, 280 mm mm Pin Wrench, 120 mm Proximal Tibia LISS Insertion Guide, left Proximal Tibia LISS Insertion Guide, right Stopper, for LISS Insertion Guides, 5 mm Insertion Sleeve, for 5.0 mm Titanium Locking Screws mm Trocar, for use with Insertion Sleeve ( ) 32 Synthes Less Invasive Stabilization System (LISS) Technique Guide

34 Pull Reduction Instrument, for LISS mm Kirschner Wire Measuring Device, for LISS Fixation Bolt, for LISS Insertion Guides Stabilization Bolt, for LISS Insertion Guides mm Hexagonal Screwdriver Shaft, self-retaining mm Torque Limiting Screwdriver, self-retaining mm Kirschner Wire Insertion Sleeve, for use with Insertion Sleeve ( ) Synthes 33

35 Titanium Proximal Tibia LISS Implant and Insertion Guide Set ( ) Graphic Case LISS Proximal Tibia Graphic Case Instruments Proximal Tibia LISS Insertion Guide, left Proximal Tibia LISS Insertion Guide, right Stopper, for LISS Insertion Guides, 5 mm, 20 ea. Implants Titanium Proximal Tibia LISS Plates, right Holes Length (mm) Qty Titanium Proximal Tibia LISS Plates, left Holes Length (mm) Qty Note: For additional information, please refer to package insert. 34 Synthes Less Invasive Stabilization System (LISS) Technique Guide

36 LISS Instrument and 5.0 mm Titanium Locking Screw Set ( ) Graphic Case LISS Instrument Set Graphic Case Instruments mm Kirschner Wire, with threaded spade point tip, 280 mm, 10 ea mm Pin Wrench, 120 mm Insertion Sleeve, for 5.0 mm Titanium Locking Screws, 3 ea mm Trocar, for use with Insertion Sleeve ( ) Pull Reduction Instrument, for LISS, 2 ea mm Kirschner Wire Measuring Device, for LISS Fixation Bolt, for LISS Insertion Guides Stabilization Bolt, for LISS Insertion Guides, 2 ea mm Hexagonal Screwdriver Shaft, self-retaining mm Torque Limiting Screwdriver, self-retaining mm Kirschner Wire Insertion Sleeve, for use with Insertion Sleeve ( ) Implants Titanium Screw Hole Insert, 5 mm, 5 ea. 5.0 mm Titanium Locking Screws, self-drilling Length (mm) Qty Note: For additional information, please refer to package insert. Synthes 35

37 Also Available Instruments mm Drill Bit, quick coupling, 280 mm Large Hexagonal Screwdriver, long Hexagonal Screwdriver mm Drill Sleeve, for use with LISS mm Kirschner Wire Centering Sleeve Kirschner Wire Aiming Attachment, for LISS Cleaning Instrument for 3.5 mm Hex, for 5.0 mm Locking Screws X-Ray Calibrator, for use with Distal Femur LISS Implants 5.0 mm Titanium Locking Screws, self-tapping Length (mm) Synthes Less Invasive Stabilization System (LISS) Technique Guide

38 References LISS Publication Schavan, Robert et al. LISS-The Less Invasive Stabilization System for Metaphyseal Fractures of Femur and Tibia. OTA Poster #1. Vancouver, B.C Subcutaneous Plating and Treatment of the Vascular Structures Baumgaertel, M. et al. Fracture healing in biological plate osteosynthesis. Injury ; 29, 3. Farouk, O., C. Krettek, T. Miclau, P. Schandelmaier, P. Guy, and H. Tscherne. Minimally invasive plate osteosynthesis: does percutaneous plating disrupt femoral blood supply less than the traditional technique? Journal of Orthopaedic Trauma. 1999; 13, 6. Gerber, C., J.W. Mast and R. Ganz, Biological internal fixation of fractures. Archives of Orthopaedic Trauma Surgery. 1990; 109. Krettek, C., P. Schandelmaier, T. Miclau, and H. Tscherne. Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury. 1997; 28, 1 (suppl). Krettek, C. and T. Miclau, Minimally invasive plate osteosynthesis and vascularity: preliminary results of a cadaver injection study. Injury. 1996; 10, 6. Indirect Reduction Ruedi, Thomas, Christophe Sommer and Adrian Leutenegger. New techniques in indirect reduction of long bone fractures. Clinical Orthopaedics and Related Research. 1998; 347. Mast, Jeffrey et al. Planning and Reduction Technique in Fracture Surgery. Springer Verlag Locking Screw Constructs Tepic, S. and S.M. Perren, Biomechanics of the PC-Fix Internal Fixator. Injury. 1995; 26, 2 (suppl). Related Implants Karnezis, I.A., A.W. Miles, J.L. Cunningham and I.D Learmouth. Biological Internal Fixation of Long Bone Fractures: A Biomechanical Study of a Noncontact Plate System. Injury. 1998; 29, 9. Miclau, T. et al. A Mechanical Comparison of the Dynamic Compression Plate, Limited Contact-Dynamic Compression Plate, and Point Contact Fixator. Journal of Orthopaedic Trauma. 1995; 9, 1. Other Helpful References Krettek, C., T. Miclau, O. Grün, P. Schandelmaier, and H. Tscherne. Intraoperative Control of Axes, Rotation and Length in Femoral and Tibial Fractures. Injury. 1998; 29, 3 (suppl). Synthes 37

39 Synthes (USA) 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. Synthes is a trademark of Synthes, Inc. or its affiliates. Printed in U.S.A. 2/10 J3342-G