Chapter 7 - Veterinary Instrumentation

www.vetinst.comTRAUMA IMPLANTS & INSTRUMENTS 7AO Type Screws, Plates and EquipmentDRILL & EQUIPMENT for Cortical and Cancellous ScrewsCORTICAL = CSCORTICAL SELF TAP = CSST SELF- SELF SELF- SELF-CANCELLOUS = CAN TAPPING SMALL TAPPING TAPPING SMALL SMALL TAPPINGCORTICAL CORTICAL CORTICAL CANCELLOUS CORTICAL CORTICAL CORTICAL CANCELLOUS CORTICAL CANCELLOUS CORTICAL CANCELLOUS CORTICAL CORTICAL CANCELLOUS1.5 2.0 2.0 2.2 2.4 2.7 2.7 3.0 3.5 3.5 3.5 4.0 4.5 5.5 6.5PILOT DRILL 1.1 1.5 1.5 1.5 1.8 2.0 2.0 2.0 2.5 2.0 2.5 2.5 3.2 4.0 3.2JACOBS HARD H090100 H090101 H090101 H090101 H090208 H090102 H090102 H090102 H090112 H090102 H090112 H090112 H090105S H090107 H090105SJACOBS SOFT - 090101 090101 090101 N/A 090102 090102 090102 090112 090102 090112 090112 090105 090107 090105SYNTHES FIT S090100S S090101S S090101S S090101S N/A S090102S S090102S S090102S S090112S S090102S S090112S S090112S S090105S S090107 S090105STAP - QUICK FIT TD0015 TD0020 N/A N/A N/A TS0027 N/A N/A TS12535 TS17535 N/A TS17535 TS00045 TS00055 TS00065TAP - ‘T’ BAR TBT015 TBT020 N/A N/A N/A TBT027 N/A N/A TBT12535 TBT17535 N/A TT17535 TBT045 - TBT065CLEARANCE DRILL 1.5 2.0 2.0 2.0 2.4 2.7 2.7 3.0 3.5 3.5 3.5 4.0 4.5 5.5 6.5JACOBS HARD H090101 H090102 H090102 H090102 H090209 H090104 H090104 H090205 H090106S H090106S H090106S H090107 H090108S H090109 -JACOBS SOFT 090101 090102 090102 090102 N/A 090104 090104 - 090106 090106 090106 090107 090108 - -SYNTHES FIT S090101S S090102S S090102S S090102S N/A S090104S S090104S SDD1500 S090106S S090106S S090106S S090107 S090108S S090109 -SCREW DRIVER - TYPE 1.5 HEX 1.5 HEX 1.5 HEX 1.5 HEX 1.5 HEX 2.5 HEX 2.5 HEX 2.5 HEX 2.5 HEX 2.5 HEX 2.5 HEX 2.5 HEX 3.5 HEX 3.5 HEX 3.5 HEXSDHS20F SDHS20F SDHS20F SDHS20F SDHS20F SDHS35F SDHS35F SDHS35F SDHS35F SDHS35F SDHS35F SDHS35F SDH3500 SDH3500 SDH3500Larger table available on page 399.7Compression Plates and Cortical Screws(AO/ ASIF type)By carefully positioning screws within the special holes of compressionplates, compression can be exerted at the reduced fracture site as thescrew is tightened. As the spherical head of the screw strikes the rearedge of the hole in the plate, the screw, (and the attached bone) areforced away from the edge of the hole and towards the fracture site.The object of compression is to provide for primary bone union. A specialguide must be used to position accurately the screw hole within the plate.The oval shaped holes in DCP’s allow a greater range of screwangulations than round hole plates. Cortical screws are available in bothtapped and self tapping formats.AO type screws and plates have, for many years, been the human and veterinary standard implants.They were originally designed in the 1950s by the AO study group [Arbeitsgemeinschaft fürOsteosynthesefragen (English: Association for the Study of Internal Fixation, AO/ASIF) ] which continuesto this day to lead the world in implant design. The design of the spherical screw head and thecompression hole are particularly important as, unless made to very exacting specifications, they will notwork properly together.The composition and design of AO type implants are laid down in very detailed international standards.The specification for plates and screws are detailed below. Provided implants are made to theseexacting standards it is safe to mix and match sources. Be very wary about using implants which maynot comply.MaterialsBS 7252-1:1997 ISO 5832-1:1997BS 7252-3:1997 ISO 5832-3:1996BS 7252-9:1993 ISO 5832-9:1992BS ISO 5832-2:1999Bone ScrewsBS 3531-5.3:1991, ISO 5835:1991BS 3531-5.6:1991, ISO 6475:1989BS 3531-5.4:1993, ISO 9268:1988Metallic materials for surgical implants. Specification for wrought stainless steel.Metallic materials for surgical implants. Specification for wrought titanium 6al4v.Metallic materials for surgical implants. Specification for high nitrogen stainless steelImplants for surgery. Metallic materials. Unalloyed titanium.Implants for osteosynthesis. Bone screws and auxiliary equipment. Specification for the dimensions of screwshaving hexagonal drive connection, spherical under-surfaces and asymmetrical thread.Implants for osteosynthesis. Bone screws and auxiliary equipment. Specification for the mechanicalrequirements and test methods for screws having asymmetrical thread and spherical undersurface.Implants for osteosynthesis. Bone screws and auxiliary equipment. Specification for screws havingsymmetrical and asymmetrical thread and conical undersurfaces.Bone PlatesBS 3531- 23.1:1991 ISO 9585:1990 Implants for osteosynthesis. Bone plates. Method for determination of bending strength and stiffness.BS 3531- 23.2:1993 ISO 9269:1988 Implants for osteosynthesis. Bone plates. Specification for holes and slots for use with screws of 4.5mm4.2mm 4.0mm 3.9mm 3.5mm and 2.9mm nominal sizes.BS 3531- 23.3:1991 ISO 5836:1988 Implants for osteosynthesis. Bone plates. Specification for holes corresponding to screws with asymmetricalthread and spherical under surfaces.159