TPLO Plate. Tibial plateau leveling osteotomie in the canine proximal tibia.

Transcription

1 TPLO Plate. Tibial plateau leveling osteotomie in the canine proximal tibia. Technique Guide Synthes Veterinary

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3 Table of Contents Introduction Tibial Plateau Leveling Osteotomy Plate 2 Indications 4 AO ASIF Principles of Internal Fixation 5 Implant Features 6 Clinical Cases 8 Surgical Technique Plate Contouring and Positioning 9 Drill Guide Technique 10 Screw Insertion Sequence 12 Product Information Implants 15 Instruments 19 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 1

4 Tibial Plateau Leveling Osteotomy Plate The Synthes Tibial Plateau Leveling Osteotomy (TPLO) Plate is part of a stainless steel plate and screw system that merges locking screw technology with conventional plating techniques. The TPLO Plate has many similarities to existing bone fixation plates, with a few important improvements. The technical innovation of locking screws and an anatomical contour provide the ability to create a fixed-angle construct while following familiar AO plating principles. ` Features and Benefits* Available in right and left versions Uses either conventional or locking screws Precontoured for anatomic fit Plate head specifically designed to engage more bone Plate head holes angled away from the articular surface and osteotomy for optimal locking screw placement. Precontoured shape for anatomical fit Combi hole accepts locking or cortex screw Limited-contact profile preserves bone vascularity * Patent pending design 2 Synthes TPLO Plate Technique Guide

5 LCP Locking Compression Plate Angular stable fixation of fragments regardless of bone quality A B C Minimised risk of primary and secondary loss of reduction, even under high dynamic loading Reduced impairment of periosteal blood supply due to the limited plate contact Good purchase also in osteoporotic bone and in multifragment factures Head screw angulations A. Cranial screw: 5 caudal B. Proximal screw: 3 distal/5 caudal C. Caudal screw: 3 cranial Head holes accept locking, cortex or cancellous bone screws DCP holes provide axial compression LCP combi-hole Intraoperative choice between compression and angularly stable locking With standard screws: interfragmental or dynamic-axial compression Rounded edges minimize soft tissue irritation With locking screws: stable plate-screw connection without loss of reduction, regardless of plate modelling Synthes 3

6 Indications The Synthes Tibial Plateau Leveling Osteotomy (TPLO) Plate is intended for use in stabilizing osteotomies of the canine proximal tibia. 4 Synthes TPLO Plate Technique Guide

7 AO ASIF Principles of Internal Fixation In 1958, the AO ASIF (Association for the Study of Internal Fixation) formulated four basic principles for internal fixation, which are still believed to be valid today. 1 The Synthes Tibial Plateau Leveling Osteotomy (TPLO) Plate has been designed with these principles in mind. These principles are: Anatomical reduction The TPLO Plate is designed to anatomically fit the proximomedial canine tibia, providing proper alignment and optimal function of the repaired stifle. Stable fixation The TPLO Plate provides stable fixation of the canine proximal tibia to promote healing at the osteotomy site. When used with locking screws, the plate and screw construct provides a locked, fixed-angle construct. Preservation of blood supply (to the bone) The limited-contact profile, rounded edges, and anatomical design of this plate assist in preservation of the blood supply by minimizing surface contact with the bone and disruption of soft tissue, and preserving bone vascularity. Early mobilization The TPLO Plate provides secure fixation which may contribute to pain reduction and permits early, active rehabilitation conducive to optimal recovery. 1 A.L. Johnson, J. Houlton, R. Vannini (2005) AO Principles of Fracture Management in the Dog and Cat, Stuttgart: Thieme. Synthes 5

8 Implant Features Plate design Holes The 3.5 mm TPLO plate is designed with three distinct screwhole technologies to accommodate all plating modalities. Along its shaft are two DCP holes separated by a central Combi hole; in its head are three stacked Combi holes. Limited contact The limited-contact shaft design reduces plate-to-bone contact area to preserve vascularity and optimize bone healing. The DCP holes accept cortex screws that may be placed in either loaded or neutral positions, depending on whether or not interfragment compression is desired (see Universal Drill Guide for more detail). The Combi hole in the center of the plate shaft accepts either a cortex screw or a locking screw. The cortex screw should be placed in the unthreaded portion of the Combi hole in either a loaded or neutral position. A locking screw may be used in the threaded portion of the Combi hole when indicated. Stacked Combi hole Combi hole DCP hole The three stacked Combi holes in the plate head accept either cortex, cancellous bone, or locking screws. If locking screws are to be used in conjunction with cortex or cancellous bone screws in the plate head, the locking screws must be inserted after the other screws have been inserted and tightened. Fixed angle stability The threads on the head of the locking screws mate with the threaded plate holes to form a fixed-angle construct that can increase load transfer. When compared to conventional plate-and-screw constructs, the angular and axial stability of locking screws increase the strength of the construct under load without requiring precise anatomical contouring. Angled threaded holes in the head of the TPLO plate help ensure that screws are angled away from the articular surface and osteotomy. Anatomical contour The anatomically shaped TPLO plate is contoured to match the medial aspect of the canine proximal tibia. This can reduce or eliminate the need for additional shaping of the plate. All implants are made of implant quality 316L stainless steel 6 Synthes TPLO Plate Technique Guide

9 Locking screws Screw head The tapered, double-lead machine thread on the head of the locking screw mates with the Combi hole in the plate. This results in stable fixation of the bone fragment without having to compress the fragment to the plate. A perfectly contoured plate is therefore not required to achieve stable fixation. Thread profile Because locking screws do not compress the plate to the bone, the pull-out mode of failure is not applicable to locking screws. Instead, locking screws fail under cantilever loading. For this reason, locking screws are made with a larger core diameter and smaller thread profile. This results in increased mechanical strength over comparably sized cortex and cancellous bone screws. Stardrive recess Double-lead locking threads mate with the threaded portion of the plate Self-tapping flutes Note: The self-tapping flutes of the locking screw make pretapping unnecessary. Drive mechanism The Stardrive recess of a locking screw provides three significant improvements over an internal hex drive. First, stripping of screw heads is minimized as a failure mode, which results in a much higher tolerance to wear for the screwdriver. Second, the tapered Stardrive recess provides automatic screw retention without the need for an additional screw holding mechanism. Third, the more efficient Stardrive recess allows a smaller screw head and flush fitting to the plate. All implants are made of implant quality 316L stainless steel. Synthes 7

10 Clinical Cases Case 1 A 74-lb., six-year-old, neutered female Labrador presented with acute lameness and a painful stifle. The use of three locking screws in the plate head ensures optimal stabilization of the proximal portion of the tibia. The distal portion of the tibia is stabilized using cortex screws in the plate shaft. Preoperative AP Preoperative Lateral Postoperative AP Postoperative Lateral 8-week Follow-up AP 8-week Follow-up Lateral Case 2 An 86-lb., three-year-old, neutered female German Shepherd presented with left hind limb lameness of one week duration. This patient was previously diagnosed with multicentric B-cell lymphoma. Her medication regime includes Leukeran 30 mg every fourteen days, Methotrexate 2.5 mg twice weekly, Prednisone 25 mg every other day, and Pepcid 20 mg once daily. Similarly to Case 1, three locking screws were used in the plate head to ensure optimal stabilization of the proximal portion of the tibia. The distal portion of the tibia was stabilized using cortex screws in the plate shaft. Preoperative AP Preoperative Lateral Postoperative AP Postoperative Lateral 8-week Follow-up AP 8-week Follow-up Lateral 8 Synthes TPLO Plate Technique Guide

11 Plate Contouring and Positioning Plate contouring If three locking screws will be used in the plate head holes, perfect contour match to the bone is unnecessary since the locking screws will not compress the plate to the bone. If conventional screws will be used in the plate head holes, perfect contour match is desirable. Note: Contouring of the plate may redirect the angle of the locking screws. It is best to avoid contouring around the head holes as this can distort the internal threads. Plate positioning The TPLO Plate should be positioned on the medial surface of the tibia, in a manner that best fits the bone contour and osteotomy. The plate is designed to be placed very proximally, just distal to the articular surface. The proximal head screw is angled 3 distal/5 caudal, away from the articular surface. Synthes 9

12 Drill Guide Technique LCP drill sleeve The 2.8 mm LCP drill sleeve fits the threaded holes of the TPLO Plate. When a locking screw is planned, a LCP drill sleeve must be used for guiding the drill bit in the proper direction Note: The LCP drill sleeve can also be used intraoperatively as a reference for visualizing the angle at which the locking screws will engage the bone. 10 Synthes TPLO Plate Technique Guide

13 Universal drill guide The Universal Drill Guide is the only drill guide which functions in all Synthes plate holes. When a cortex or cancellous bone screw is used, it is recommended that a Universal Drill Guide be used to guide the drill bit. If the screw is intended to achieve interfragment compression, the Universal Drill Guide should be placed in the load position, as shown and described in the figure below. If the screw is intended to hold the plate, the Universal Drill Guide should be placed in the neutral position Compression (load) position Compression is achieved by placing the Universal Drill Guide in the eccentric position, and maintaining the drill guide body above the plate as shown. Compression (load) Neutral position Neutral position is achieved by placing the Universal Drill Guide in the eccentric position, then compressing the drill guide body into the hole, which will shift the drill guide into the neutral position as shown. Note: For illustrative purposes, a Combi hole has been depicted. The same methodology applies to LC-DCP and DCP holes. Neutral Synthes 11

14 Screw Insertion Sequence It is recommended that screws be inserted in the sequence described below: 1 Proximal In the proximal DCP shaft hole, place a conventional cortex screw in compression (load) position. This screw should be left slightly loose, by about one turn. Ensure that the plate continues to be pushed proximally against this screw, before the next screw is placed. Note: When locking screws are used, a space between the undersurface of the plate and the proximal bone fragment may occur. Do not push the proximal, head portion of the plate onto the bone. Cranial Caudal 1 Cortex screw in compression position (left slightly loose) Distal 2 Place either a conventional cortex screw or locking screw in the most cranial head hole of the plate. Fully tighten this screw. If both cortex and locking screws are used in the plate head, place all cortex screws first and then place all locking screws. 2 Locking or cortex screw Note: Locking screws should not be tightened more than 1.5 Nm. Overtightening may cause a cold weld and screw removal may be difficult.* * See p.20 for 1.5 Nm Torque Limiting Attachment. 12 Synthes TPLO Plate Technique Guide

15 3 Place either a conventional cortex screw or locking screw in the most proximal head hole of the plate. Fully tighten this screw. If both cortex and locking screws are used in the plate head, place all cortex screws first and then place all locking screws. 3 Locking or cortex screw 4 In the most distal DCP shaft hole, place a conventional cortex screw in the compression position. After ensuring that the first cortex screw (described in step 1) is slightly loose, fully tighten the compression screw in this hole. Return to the cortex screw described in step 1 and tighten fully.* * (fully tighten) Note: Check for compression and alignment of osteotomy before placing the final screw. 4 Cortex screw in compression position Synthes 13

16 Screw Insertion Sequence 5 If a jig is used, it may need to be removed to provide access to this screw hole. 5 Locking or cortex screw Place either a conventional cortex screw or locking screw in the most caudal head hole of the plate. Fully tighten this screw. If both cortex and locking locking screws are used in the plate head, place all cortex screws first and then place all locking screws. Note: It is highly recommended that at least one locking screw be used in the proximal, head portion of the TPLO Plate (steps 2, 3, and 5). 6 In the midshaft Combi hole, place either a conventional cortex screw in the nonthreaded portion of the hole or a locking screw in the threaded portion of the hole. Fully tighten this screw. Check tightness of screws placed in steps Locking or cortex screw in neutral position 14 Synthes TPLO Plate Technique Guide

17 Implants 3.5 mm Tibial Plateau Leveling Osteotomy (TPLO) Plate, left Holes Length Thickness VP4401.L3 3 holes, proximal 66 mm 3.7 mm 3 holes, distal 3.5 mm Tibial Plateau Leveling Osteotomy (TPLO) Plate, right Holes Length Thickness VP4401.R3 3 holes, proximal 66 mm 3.7 mm 3 holes, distal Synthes 15

18 Implants Locking Screw Stardrive 3.5 mm, self-tapping Steel Length (mm) Cortex Screw 3.5 mm Steel Length (mm) Synthes TPLO Plate Technique Guide

19 Cortex Screw 3.5 mm, self-tapping Steel Length (mm) Synthes 17

20 Implants Cancellous Bone Screw 4.0 mm, fully threaded Steel Length (mm) Cancellous Bone Screw 4.0 mm, short thread Steel Length (mm) Thread length (mm) Screw Reference Chart Thread Diameter 3.5 mm 3.5 mm 4.0 mm Screw Type Cortex Locking Cancellous Drill Bit for 2.5 mm 2.8 mm 2.5 mm Threaded Hole Tap 3.5 mm Self-Tapping 4.0 mm Drive Type 2.5 mm T mm Hexagonal Stardrive Hexagonal 18 Synthes TPLO Plate Technique Guide

21 Instruments LCP Drill Bit, 2.8 mm, quick coupling LCP Drill Sleeve 3.5 mm, for Drill Bits 2.8 mm Stardrive Screwdriver, T Stardrive Screwdriver Shaft, quick coupling Centering Sleeve for Kirschner Wire 1.6 mm, length 70 mm mm Universal Drill Guide Synthes 19

22 Instruments for Locking Screws Bending Pin for LCP Plates, 3.5 mm, with thread Instrument for temporary reduction Also available PHILOS Direct Measuring Device for Kirschner Wire 1.6 mm Torque Limiting Attachment, quick coupling, 1.5 Nm 20 Synthes TPLO Plate Technique Guide

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24 04/ Synthes, Inc. or its affiliates Subject to modifications LCP and Stardrive are trademarks of Synthes, Inc. or its affiliates Presented by: Ö öAAbä version AA rev. 1