Disclosures Synthes A Biomechanical Comparison Between Superior and - PowerPoint PPT Presentation

5/8/2014 Disclosures � Synthes A Biomechanical Comparison Between Superior and � OREF Anterior Plating Positions for Mid-Shaft Clavicle Fractures Using Pre-contoured Plates � JOJ Paul Toogood, MD/MS, Dezba Coughlin, PhD, David Rodriguez, Jeffery Lotz, PhD, Brian Feeley, MD Canadian Orthopaedic Trauma Society Nonoperative Treatment Compared with Background Plate Fixation of Displaced Midshaft JBJS, 2007 Clavicular Fractures DASH: � Historic data suggested Multicenter, prospective RCT � � Better in ORIF at all time points up to 1 yr extremely low non-union � N = 132 � Constant Score: rates with mid-shaft � 67 ORIF � Better in ORIF at all time points up to 1 yr clavicle fractures � 65 sling Time to Union: � � � Neer, JAMA, 1960: ORIF: 16.4 wks Outcomes � � Sling: 28.4 wks � DASH � 2235 non- � Non-unions: � Constant Score operatively treated ORIF: 2 � � clavicles Sling: 7 Radiographic/clinical f/u � � Complications: � � 3 nonunions ORIF: 37% (hardware irritation, infection) � Sling: 63% (non-union, malunion requiring � treatment 1

5/8/2014 Plate Position Prior Literature Anterior Superior No clinical comparisons � Biomechanical Data: � � Celestre, 2008, JOT � Harnroongroj, 1996, Clin Biomech Favored superior plating � Iannotti, 2002, JSES � Robertson, 2009, JSES � Taylor, 2011, Clin Biomech 1) Less prominent (less ROH) Favored anterior plating 2) Longer anterior-posterior 1) Flat surface � Partal, 2010, JOT screw purchase 2) Less muscular stripping 3) Instrumentation away from at risk neurovascular structures Prior Literature: Limitations Transverse Fracture Pattern Author Implants Loading Fracture Model 1/3 rd Tubular Harnroongroj, Bending Transverse Fx 1996 Iannotti, 2002 Reconstruction Compression, Transverse Fx Torsion Celestre, 2008 DCP Compression, Transverse Fx Torsion, Bending Robertson, 2009 Reconstruction Compression, Transverse Fx Torsion, Bending Partal, 2010 Reconstruction Compression, Transverse Fx Torsion, Bending Epidemiologic data suggests these fractures are uncommon (~5%) clinically 2 . Taylor, 2011 Pre-contoured Bending Transverse Fx Prior authors admit it is also uniquely stable fracture pattern1 2,15 .. 2

5/8/2014 Purpose Methods: Fracture Model OTA/AO/ASIF Classification � To biomechanically compare superior and anterior plating positions of: � Clinically relevant mid-shaft clavicle fracture patterns � Using pre-contoured plates � When loaded in axial compression, torsion, and cantilever bending. Methods: Fracture Model Methods: Fracture Model •Bending Wedge Fracture Pattern (B2.2): •Oblique Fracture Pattern (B1.2): •The entire B2 category is •Single most common fracture pattern amongst the more common (26.3%) 2 . fracture patterns (28.9%) 2 . •More reproducible than the spiral pattern, •Of the three, it was felt the and less tested than the transverse pattern. Bending wedge would be the most reproducible. 3

5/8/2014 Methods: Fracture Model Methods: Fracture Model x75 B1.2: 32 degrees, superior-lateral to inferior medial •Comminuted Fracture Pattern (B3.3): •When segmental fractures occur, they are B2.2: Wedge will be 16% of clavicular length overwhelmingly comminuted (79.9%) 2 . B3.3: Comminuted section will be 21% of clavicular length Methods: Clavicle Model Methods: Implants 1) Pre-contoured Superior Left Locking Mid-shaft � Synthetic clavicles (Pacific Research Laboratories Clavicle Plate, 8-hole model 3408-1) � Easier to obtain � Reduces variability in bone geometry and quality � > 2 testing groups 2) Pre-contoured Anterior Left Locking Mid-shaft Clavicle Plate, 8-hole � Now produce an intact model Three locking screw on each side of the fracture Lag screws placed across oblique and wedge patterns 4

5/8/2014 Methods: Loading 6 Superiorly Plated Torsion � Axial Compression � Cantilever 12 Oblique B1.2 6 Anteriorly Plated Torsion � Axial Compression � Cantilever Osteotomy 6 Superiorly Plated Torsion � Axial Compression � Cantilever 12 Bending Wedge B 2.2 6 Anteriorly Plated Torsion � Axial Compression � Cantilever Osteotomy Compression 6 Superiorly Plated Torsion Torsion � Axial Compression � Cantilever 12 Complex Cantilever bending Comminuted B 3.3 6 Anteriorly Plated Torsion � Axial Compression � Cantilever Results: Axial Compression Results: Torsion Axial Compression Torsion Clockwise Torsion Counter-Clockwise Superior Plate Anterior Plate Superior Plate Anterior Plate * Superior Plate Anterior Plate 973 914 805 3142 735 2873 650 573 552 578 433 465 418 455 1657 1257 1212 1008 Oblique Wedge Comminuted Oblique Wedge Comminuted Oblique Wedge Comminuted Superior stiffer than anterior for all fracture patterns Superior stiffer than anterior for all fracture patterns, except no difference oblique fx clockwise torsion* Oblique stiffer than wedge & comminuted patterns Oblique stiffer than wedge & comminuted patterns 5

5/8/2014 Results: Cantilever Bending Anterior Plate Cantilever Bending Anterior � Resistance to Superior Plate Anterior Plate Cantilever bending 116 100 � Lies with a larger 75 69 dimension (width) perpendicular to the 41 line of force 25 Superior Oblique Wedge Comminuted Anterior stiffer than superior for all fracture patterns Oblique stiffer than wedge & comminuted patterns Superior Plate Limitations � Resistance to Torsion � Little is know about in vivo loading of the clavicle � Greater mass (18.5 vs � Clinical failure is fatigue vs construct stiffness 13 gm) � Sequential testing � S-shape � Moves mass away from centeroid, increasing polar moment of inertia Superior � Resistance to Compression Anterior � Flat along axis of compression 6

5/8/2014 Conclusions References 1) Neer CS 2 nd . Nonunion of the clavicle. JAMA. 1960;172:1006-11. � 2) Robinson CM. Fractures of the clavicle in the adult: Epidemiology and classification. J Bone Joint Surg [Br]. 1998;80-B:476-84 � 3) Hill JM. Closed treatment of displaced middle third fractures of the clavicle gives poor results. J Bone Joint Surg [Br]. 1997;79-B:537-9 � Current study suggests that for multiple mid- � 4) McKee MD. Mid-shaft malunions of the clavicle. J Bone Joint Surg. 2003;85-A:790-97 � 5) McKee MD. Deficits following treatment of displaced midshaft clavicular fractures. J Bone Joint Surg. 2006;88:35-40 shaft clavicle fracture patterns: � 6) Nowak J. Sequelae from clavicle fractures are common. Acta Ortho. 2005;76:496-502 � 7) Zlowodzki M. Treatment of acute midshaft clavicle fractures: systematic review of 2144 fractures: on behalf of the evidence based orthopaedic trauma � working group. J Orthop Trauma. 2005;19:504-7. � Compression and torsion appear better controlled with 8) Canadian Orthopaedic Trauma Society. Nonoperative treatment compared with plate fixation of displaced mid-shaft clavicular fractures. A multi- � center, randomized clinical trial. J Bone Joint Surg. 2007;89:1-10. a pre-contoured superior plate 9) Kloen P. Anteroinferior Plating of Midshaft Clavicular Nonunions. J Orthop Trauma. 2002;16(6):425-30. � 10) Collinge C. Anterior-inferior Plate Fixation of Middle-third Fractures and Nonunions of the Clavicle. J Orthop Trauma. 2006;20(10):680-685. � 11) Chen C. Anterior-inferior plating of middle-third fractures of the clavicle. Arch Orthop Trauma Surg. 2010;130(4):507-11. � Cantilever bending is bettered resisted by the improved � 12) Celestre P. Biomechanical evaluation of clavicle fracture plating techniques: Does a locking plate provide improved stability? J Orthop Trauma. � 2008;22(4):241-7 areal moment of inertia of the pre-contoured anterior 13) Harnroongroj T. Biomechanical aspects of plating osteosynthesis of transverse clavicular fracture with and without inferior cortical defect. Clin � Biomech. 1996;11(5);290-4 plate 14) Iannotti MR. Effects of plate location and selection on the stability of midshaft clavicle osteotomies: A biomechanical study. J Should Elbow Surg. � 2002;11(5):457-62 15) Robertson C. Reconstruction plates for the stabilization of mid-shaft clavicle fractures: Differences between nonlocked and locked plates in two � � Until the relative importance of these forces is different positions. J Should Elbow Surg. 2009;18:204-9 16)Taylor P. The comminuted midshaft clavicle fracture: A biomechanical evaluation of plating methods. Clinical Biomechnics. Article in Press. � known, reasons other than biomechanics should 17) Partal G. Superior versus Anteroinferior Plating of the Clavicle Revisited: A Mechanical Study. J Orthop Trauma. 2010;24(7):420-24. � 18) Allman F. Fractures and ligamentous injuries of the clavicle and its articulation. J Bonr Joint Surg [Am]. 1967;49-A:774-84. � be used to determine plate position 19) Harrington M.A.J. Geometric properties and the predicted mechanical behavior of adult human � clavicles. J Biomech. 1993;26(4–5):417–426. � 7