Scaphoid Fixation Iliac Crest vs Distal Radius Bone Graft A Biomechanical Study Vera Kinzel Paul Jarrett Karl Stoffel Fremantle Hospital,WA
Introduction Most common fracture of carpus Displaced fractures/Non-unions: - require ORIF - +/- bone grafting Common graft sites -Distal radius -Iliac crest
Introduction lliac crest: -most common source of bone graft -better quality of osteoprogenitor cells -better biomechanical properties -accurately restore shape and size of s. -higher donor site morbidity -long incision -painful donor site
Introduction Distal radius graft: -no perceptible co-morbidities -easy to shape -increasing skin incision by just 2 cm -vascularised bone graft
Aim Biomechanical properties of scaphoid fractures with different bone grafts Guide future clinical practise Establish scaphoid morphology
Methods Fresh frozen cadaver wrist: - 14 paired wrist - 28 scaphoids - thawed to room temperature 12 hours prior to testing - soft tissue removed - leaving scaphoid and cartilage intact
Methods Photographed
Methods Weighted Measured
Methods CT
Methods CT
Methods DEXA bone desitometry
Methods Osteotomy -5 mm midwaist -custom made jig
Methods Paired scaphoids -Randomised left /right iliac crest or distal radius corticocancelleous grafts Cannulated compression screw (Titanium miniAcutrek® screw, Acumed)
Methods
Post Grafting
Methods Scaphoid was cemented into standard nut Orientated to scaphoid axis Placed into material testing machine (Zwick Z010, Test-Expert-Software Zwick, Inc., Ulm, Germany)
Methods Testing: - Gradual loading - Assessment of load to failure Data: - Load to 2 mm displacement - Load to failure - Moment at 2 mm displacement - Moment at failure - Stiffness
Methods
Statistics Significance paired Students’ t-test Statistical significance accepted at 0.05 level
Results Morphology: Weight:4.57 g Volume:2413 mm 3 Density:0.39 g/cm 2 Height:11.4 mm Length:29.3 mm Width Waist13.7 mm
Results Morphology: Many features vary considerably Basic shape similar Significant difference - Dimension - Density
Results Load 2 mm displacement
Results Load at failure
Results Moment at 2 mm
Results Moment at Failure
Results Stiffness
Summary No significant difference in biomechanical testing between Iliac crest and distal radius bone graft
Discussion Insufficient literature on different grafts Iliac crest and distal radius provide grafts - suitable size/shape Iliac crest: - creates closer morphology
Discussion Biomechanical properties similar Distal radius source of less donor site morbidity
Discussion Limitation of study: -Ex vivo study -No conclusion on: - Osteoprogenitor cells - healing cadaver bone -unknown handedness - most likely elderly donors - ? differences to actual fracture population
Thank you