DIAG IM3 - Page 130

15Internal 3 Dental Equipment Fixation & Instrumentation Locking Plates www.vetinst.com VILock 2.0 Plates with Stacked Locking Holes Our 2.0mm stacked hole locking plates can be used either with our 2.0mm locking screws or with 2.0mm cortical/cortical self-tap screws. In common with all locking plate constructs, when used with locking screws, precise contouring to the bone surface is not required. Leaving a small gap between plate and bone helps minimise damage to the periosteal blood supply. Closely positioned holes (6mm between centres) makes these plates very useful for smaller fragments. Plate profiles on page 361. fine threads lock head into plate. large core to resist bending. coarser threads than head but still finer than cortical screw for max bone screw interface. LOCKING 2.0 PLATES Standard DCP or Round Hole Plates are held into position by being trapped between the head of the screw and the bone. Tightening the screw pulls the bone up to the plate. When the screw is tight the threads of the screw pull against the bone holding the plate in position. The situation with locking screws and plates is very different. Although the threads of the screw shaft engage the bone, the interface between bone and screw is not related to attachment of the plate. In locking plates and screws it is the interface between the screw head and the plate which attaches the plate to the screw. As the screw is tightened the bone maintains its position relative to the plate, it is not drawn up to it. The screw head engages with the plate. This has a number of implications: LPSH200425 LPSH200531 LPSH200637 LPSH200743 LPSH200849 LPSH200955 LPSH201061 LPSH201167 LPSH201273 LPSH201379 LPSH201485 LS20PSET Contouring of Plates With standard DCPs the plate must be contoured exactly. When the screws are tightened the bone fragments will be pulled towards the plate and assume the contour of the plate. If the plate is not contoured correctly the screws will pull the fragments out of alignment. Using a locking plate and screws once the plate is applied the bone fragments will be held in position relative to one another as is the case with external fixation. Indeed locking plates are sometimes referred to as ‘internal, external fixation’. Locking plates do not therefore require contouring in the same way as DCP type plates. This has particular relevance in the TPLO procedure where contouring the plate is very important and very time consuming. If a Standard Locking TPLO Plate fits all TPLO osteotomies there are significant savings in terms of time and morbidity. 2.0mm Locking Plate 4 Hole 25mm Long 2.0mm Locking Plate 5 Hole 32mm Long 2.0mm Locking Plate 6 Hole 37mm Long 2.0mm Locking Plate 7 Hole 43mm Long 2.0mm Locking Plate 8 Hole 49mm Long 2.0mm Locking Plate 9 Hole 55mm Long 2.0mm Locking Plate 10 Hole 61mm Long 2.0mm Locking Plate 11 Hole 67mm Long 2.0mm Locking Plate 12 Hole 73mm Long 2.0mm Locking Plate 13 Hole 79mm Long 2.0mm Locking Plate 14 Hole 85mm Long 2.0mm Locking Plate Set £54.08 £55.62 £57.68 £59.74 £61.80 £63.86 £65.92 £67.98 £70.04 £72.10 £74.16 £695.25 VILock 2.4 Plates with Stacked Locking Holes Screw Angulation and Numbers In order to fit and lock into the plate the screw must be inserted at a fixed angle relative to the hole in the plate. Drill Guides are provided which screw into the locking holes to ensure that this happens. It is not always desirable that the screws are at 90 degrees to the plate, particularly close to joints. The angle of the screw is dictated by the plate not the surgeon. The rigid attachment of the screw to the plate gives any locking construct a high degree of angular rigidity relative to a DCP construct where a spherical screw head in an oval hole results in a relatively flexibility. This means in any given situation that to achieve the same rigidity as a DCP construct a locking construct needs less screws. Again this has particular implications in terms of time and morbidity. It also offsets, to a degree, the higher costs of locking screws and plates. VI 2.4 locking plates have stacked locking holes as is the case with our 2.7 plates. The twin start hole in the plate is the same size as the 2.7 locking plate. The following screws may be used, locking 2.4 (LS2424**), locking 2.7 screws (LS2724**), cortical 2.4, cortical 2.7 and cancellous 3.0. Screw Diameter and Strength The increased angular rigidity places greater stresses onto the screw. 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