antebrachial fractures IN PATIENTS LESS THAN 10KG! ! ! TIM PRESTON overview • Anatomy • Aetiology ! • Pathophysiology ! • A history of complications ! • Treatment options ! • Summary anatomy review ▪Antebrachium ▪ Paired bones of radius & ulna anatomy review ▪Attachments between bones ▪ Proximal & distal radioulnar synovial joints ! ▪ Annular ligament ! ▪ Interosseous ▪ Ligament – ~2cm long, thick, radial head distal ▪ Membrane – 100% in cats; in dogs thin & perforated ! ▪ Distal radioulnar ligament ▪ Between ulna styloid and radial ulna notch anatomy review ▪Forelimb load distribution ▪Dogs ~58-67% ▪Cats ~50% (Voss, 2011) (Lascelles, 2007) ! ▪Antebrachial load distribution ▪80% radius? ▪51% radius; 49% ulna (Mason, 2005) anatomy review ▪Vessels ▪Nutrient, metaphyseal, and periosteal arterioles ▪Periosteal vessels ▪Outer 1/10 to 1/3 of cortical bone ▪Nutrient artery & medullary branches ▪Remainder of the cortex Garofalo, 2013 anatomy review ▪Important regional muscles ! ▪ Proximal ▪ Pronator teres (medial) ▪ Flexor carpi radialis (medial) ▪ Supinator (lateral) ▪ Extensor carpi radialis (lateral) ! ▪ Distal ▪ Abductor pollicus longus ▪ Extensor carpi radialis ▪ Common digital extensors Piermattei, 2006 aetiology Motor vehicles • Dogs - 77% • Cats – 90% • Bites, projectiles, stepped on…. Philips 1979 Jump down • 62% (16/26) Muir 1997 • 26% bilateral Muir 1997, Larssen 1999 aetiology ▪Radius and ulna fracture incidence & location ! - 17% of all fractures are R/U (Waters, ▪Dogs 1993) ▪70% distal 1/3rd (Philips, 1979) ▪Transverse, short oblique ! - 2-8% of all fractures are R/U ▪Cats 1979) ▪57% are mid-diaphyseal (Wallace, 2009) (Philips, pathophysiology ▪Are small breeds predisposed to R/U fracture? ▪Bone density? ▪No evidence to suggest bone is less strong ▪Bone morphometry? radial morphometry Cortical thickness (mean mm) Medial Dogs 4.5kg – distal 30% (Brianza, 2006) 2.59 Cat 3.3kg – distal 33% (Preston, 2013) 1.60 Lateral 2.84 1.36 Cranial 2.00 1.27 Caudal 1.89 1.13 pathophysiology Brianza, 2006 ▪No differences in normalised cortical thickness at distal 1/3 ▪ There is no stress concentration due to cortical thickness changes ! ▪↓Normalised cortical bone moments of inertia at distal 1/3 pathophysiology Biological Mechanical ••Infection - 0.2% (Atilola,1984) ••Blood supply ••Dogs <6kg (Welch, 1997) ••↓ intraosseous vascular density ••Distal diaphysis and metaphysis ••Cats? ••Limited soft tissue ••Large bone deficit ••Bone graft, rh-BMP 2/7 ••Instability ••Improper fracture stabilisation ••↑ interfragmentary strain ••Callus to form bone ••<2% & < 0.5 degrees ••Bone morphology ••Torsional ROM? Delayed or non-union a history of complications ▪ 3.4% overall non-union rate in dogs ▪ >2500 cases (Atilola 1984) ! ▪ Major complications ▪ Surgical revision, refracture, non-union or amputation a history of complications 100% 100% 50 years of complications McCartney, 2010 Piras, 2011 Saikku, 2005 Hamilton, 2005 Larsen, 1999 Lappin, 1983 Vaughan, 1964 •• Retrospective case series Prospective case series – 11 dogs, acute – 14 dogs 22 dogs, 23 Retrospective case series 98 • small 17 acute fracture 16 dogs, 20dogs fractures fracture • AO mini T-plate –acute 1.5/2.0 mm fractures 26 breed 18 •• Type IIainitially ESF &IM acrylic Circular ESF Polylactide plates -non-unions, 1.5/2.0 mm10 screws 46/8 chronic non-unions, acute • cast, 13/23 chronic acute 8/8 pin, 1/10 plate 12/18 casted -10non-union •• 1/17 refractured 18 weeks 50% pin tract discharge, 44% ulna resorption 1/11 4 weeks No major complications Plates used Recommendations Plate applied and@100% ‘healed’ • Long term radiographic outcome 1/16 refractured @radiographic 12 weeks (10/11) • 9/14 ulna resorption @ wks 2.0 and 2.7mm DCP, 2.0 VCP, T-plate Plates – term 87.5% return to4full function No long follow up •• Union in 10-16 • Long term radiographic outcome 9-12radial weeks outcome (12/14) 4/22 majorplace complications Don’t IM pins Recommendations –weeks check casts q5-7d • Union 4-17 weeks Owner assessed as good-excellent in • Long term in outcome External coaptation has ↑ non-union • 10/12 89% return to normal function risk • No long term radiographic review 75% 75% 67% 50% 25% 18% 10% 0% 10% 0% 1964, Vaughan 6% 6% 0% 1983, Lappin 1999, Larsen Cast/splint 2005, Hamilton Plate 2005, Saikku ESF 2010, McCartney IM pin 2011, Piras a history of complications - cats ▪Overall non-union rate 4.3% (Nolte, 2005) Wallace, 2009 ▪ R/U non-union rate of 5% Major complications in cats 100% 75% 50% 31% 28% 25% 20% 12.50% 0% 1979, Philips Cast/splint 2003, Haas Plate 2009, Wallace ESF Wallace, 2009 1979 Haas, 2003 Philips, • Retrospective case series • Retrospective case • 26 cats 5 cats series • ESF Type Ia ESF • 13 cats • 4/14 1/5 non-union • Cast • Plate Radiographic union in 6-20 • 4/13 non-union • 1/10 weeks • Mean radiographic Long term outcomeunion not 12 weeks reported external coaptation ▪Dogs ▪ 30-75% non-union ( Vaughan 1964, Sumner-Smith 1970) ▪ 63% soft tissue injury (Meeson, 2011) ▪Cats ▪ 31% non-union (Philips, 1979) ▪ 50% soft tissue injury (Meeson, 2011) ▪Post op? ▪ 12-24hrs, soft padded ▪ No evidence to suggest prolonged use helps with outcomes Not recommended bone plates ▪Types ▪ Metallic ▪ DCP, VCP or LC-DCP ▪ T plate (Larsen, 1999 , Hamilton, 2005) ▪ Straight (Larsen, 1999) ▪ Locking plates ▪ 100% union ! ( Voss, 2009) ▪ Lactides ▪ Good results in single case series (Saikku-Backstrom, 2005) ▪ 1 re-fracture (1/10) ▪ Plates ▪ Sizes ▪ 1.5/2.0 most common bone plates ▪ Application ▪ Limb alignment should be maintained ! ▪ Radius ▪ Cranial – tension side of radius ▪ Medial ▪ Stiffer, less tissue dissection and avoids extensors ▪ Limited by patient bone size ▪ Not appropriate for proximal fractures ! (Sardinas, 1997) ▪ Ulna ▪ Cats – wide in Cr-Cd plane, can take a sizeable lateral implant ▪ Dogs – tapers quickly in Cr-Cd plane, very limited bone proximally bone plates Biological osteosynth esis Preserve blood supply & soft tissue ↓envelope dissection & fracture handling Graft? Indirect or closed reduction Fracture/ limb alignment Bridging osteosynth esis Locking ↓ contouring Limited or no contact Internal fixator Dynamic screw selection dual bone fixation (DBF) ▪Wallace (2009) - cats ▪ Various stabilisation methods – n=28 ▪ DBF cases had < ½ the revision rate Dual bone 12.5% (1/8) Single bone 27.8% (5/18) ▪Witsberger (2010) - dogs ▪ Radial plate & ulna pin -MIPO ▪ Ulna pin ‘increased stiffness and strength’ of radial plate?! DBF Radial plate ! Radial plate + ulna pin Radial plate + ulna plate ! ! ! ••Stiffer than the plate ••In CC bending ••Axial compression ••Load to failure ••Not significantly stiffer than plate +pin ••In CC bending and compression ••Significantly higher yield load ••Least stiff ••Lowest load to failure Preston (2014) summary Major complications ••Dogs ••Improving with time ••0-18% ••Cats ••May be due to ↑ ROM? ••5-28% DBF provides an advantage ••Plate-rod ≠ DBF External coaptation ••Not recommended Small dogs have ••↓ blood vessels in distal third ••↓ cortical bone moment of inertia Prospective studies required • In vivo DBF vs radial plating • Define feline periosteal blood supply references & acknowledgments ▪See drop box for detailed references ▪Thanks to ▪ Prof Hosgood, Murdoch ▪ Assoc Prof Glyde , Murdoch ▪ Dr Snow , Murdoch ▪ Robert Day, Royal Perth Hospital ▪ DePuy-Synthes
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