DIAG IM3 - Page 196

15Joint 5 Dental Surgery Equipment & Instrumentation TPLO Plates with Locking Screw Holes www.vetinst.com Tips and tricks for locking TPLO plating. - The TPLO procedure is performed in the normal way, except that soft tissue elevation in the proximal tibial plateau segment is not necessary - Once the tibial plateau is rotated and the osteotomy is stabilised, the TPLO locking plate is applied to the tibia and positioned appropriately. Use a K-wire or needle to ensure that the plate is correctly positioned and is over bone at all points, particularly the proximal screw hole adjacent to the joint and the caudal proximal locking screw hole if the bone is not visible because of overlying soft tissue. Since the beginning of the millennium, the advent of locking plate technology has revolutionised TPLO surgery arguably more than any other surgical procedure. Locking TPLO plates have made the procedure quicker and simpler with less dissection and therefore biological trauma required, and post-operative osteotomy stability is better. - In the distal tibial diaphysis segment, a single non-locking screws is placed to secure the plate to the bone - TPLO locking plates use locking screws in the proximal tibial plateau segment and the plate is pre-contoured to match the shape of the proximal tibia. - Using the locking drill guide, all the proximal locking screws are placed in the tibial plateau segment. This means that the plate does not need to be contoured to the shape of the proximal tibia during surgery, which saves time and avoids potential plate weakening by doing so. - In the distal tibial diaphyseal segment, a non-locking screw is placed in compression using the compression guide; this is to compress the osteotomy. - The position and direction of the locking screws in the tibial plateau segment of the plate is designed so that the screws are positioned adjacent to, but reliably angled and directed away from the joint. This means that so long as the plate is placed correctly, intra-articular screw placement should be impossible. This is a significant advantage as the potential for intra-articular screw placement is a potential complication when TPLO is performed without locking screws; because if this happens, the surgery has to be revised to re-direct the intra-articular screw. - The remaining distal screws are placed; these may be either locking or non-locking screws at the surgeon’s preference, and depending on the plate configuration. NB before placement of locking screws in the distal tibial diaphysis segment, all non-locking screws must be fully tightened. - Given the specific position and direction of the locking screws in the tibial plateau section, the plate should not be contoured. This is because contouring the plate may result in inappropriate direction of the locking screws into the stifle joint. - As locking plates do not rely on friction generated between the plate and the bone for stability, it is not necessary to elevate soft tissues beneath the locking part of the plate. For locking TPLO application, this means that elevation of the soft tissues medial to the tibial plateau i.e. the medial buttress is no longer required. This saves time as removing the medial buttress can be time consuming, it can bleed, it minimises iatrogenic trauma, and minimises chance of medial collateral ligament damage that could occur with over-exuberant removal of the medial buttress. - As locking screws are angle stable, placement of locking screws in the tibial plateau segment means maximal stability of the tibial plateau. In other words, the chances of post-operative instability of the tibial plateau segment developing should be minimised. Post-op instability can lead to loss of osteotomy reduction, post-operative increase in tibial plateau angle, VI Locking TPLO Plates Locking TPLO Plate showing both converging and diverging Locking Screws VILock TPLO plates are available in 2.7mm, 3.5mm and 3.5mmm broad, covering the vast majority of TPLO patients. Head of Broad 3.5 Locking TPLO Plate The head section is both wider and shallower than any other locking design maximising the area of bone spanned to give very even force distribution across the whole of the proximal segment whilst also permitting a very proximal osteotomy. The locking holes are both convergent and divergent to maximise pull-out resistance and angled to avoid articular surfaces. and a complication know as “rock-back”. - Locking screws rely on locking of the screw head into the plate for security instead of screwing the screw very tightly into the bone so as to generate high frictional forces between the screw head, plate hole and bone. This means that for locking screws, the risk of stripping a screw in the bone bone is longer a possible complication, compared to non-locking screw where screw thread stripping in the bone is a real complication, particularly in the cancellous metaphyseal bone of the tibial plateau. TPLO PLATES WITH LOCKING SCREW TECHNOLOGY TPLO27LPCL TPLO27LPCR TPLO35LPCL TPLO35LPCR TPLO35BLPCL TPLO35BLPCR LSDG2724 LSDG35 The disadvantage of locking plates for TPLO surgery is that a slightly expanded inventory of implants and equipment is needed. Equipment needed includes a locking plate, locking drill guide, drill bit appropriate to the core diameter of the locking screws (e.g. for a 3.5mm locking screw, a 2.8mm drill bit rather than a 2.5mm drill bit is used), and locking screws. Use of locking plates for TPLO surgery is strongly recommended over non-locking plates. TPLO Plate Locking 2.7 Left TPLO Plate Locking 2.7 Right TPLO Plate Locking 3.5 Left TPLO Plate Locking 3.5 Right TPLO Plate Broad Locking 3.5 Left TPLO Plate Broad Locking 3.5 Right Locking Screw Drill Guide for small 2.7 3.5 Locking Screw Drill Guide For plate profiles see page 375. 180 £82.40 £82.40 £82.40 £8 "C*3"s*3"s*3SB*3SB