A biomechanical comparison of unilateral and bilateral String-of-Pearls™ locking plates in a canine distal humeral metaphyseal gap model

R. J. Hurt; J. A. Syrcle; S. Elder; R. McLaughlin

doi:10.3415/VCOT-13-10-0133

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2014; 27(03): 186-191
DOI: 10.3415/VCOT-13-10-0133

Original Research

Schattauer GmbH

A biomechanical comparison of unilateral and bilateral String-of-Pearls™ locking plates in a canine distal humeral metaphyseal gap model

R. J. Hurt

¹Mississippi State University, College of Veterinary Medicine, Mississippi State, MS, USA

,

J. A. Syrcle

¹Mississippi State University, College of Veterinary Medicine, Mississippi State, MS, USA

,

S. Elder

¹Mississippi State University, College of Veterinary Medicine, Mississippi State, MS, USA

,

R. McLaughlin

¹Mississippi State University, College of Veterinary Medicine, Mississippi State, MS, USA

› Author Affiliations

Abstract

Summary

Objective: To compare the in vitro biomechanical performance of two String-of-Pearls (SOP) plate constructs in a canine distal humeral metaphyseal gap model.

Methods: Seven pairs of canine cadaveric humeri, including the elbow joints, were prepared. One group consisted of a unilateral medially placed SOP plate with bicortical screws (UNI). The second group consisted of bilateral caudo-medial and caudo-lateral SOP plates applied with monocortical screws (BI). A 2 cm ostectomy was performed immediately proximal to the supratrochlear foramen. Constructs were tested in torsion and axial compression.

Results: The UNI constructs had significantly lower stiffness in torsion and axial compression than the BI group. However, UNI constructs had a significantly higher ultimate strength than BI constructs. All UNI constructs failed by bending of the transcondylar screw and SOP plate. All BI constructs failed by axial pullout of the distal most screws.

Clinical significance: In stabilizing canine supracondylar humeral fractures as modeled here, both the UNI model and the BI model demonstrated biomechanical advantages. The incorporation of a transcondylar screw through the medial plate appears to be beneficial to construct strength.

Keywords

Supracondylar humeral fracture - mechanical testing - humerus - SOP - String-of-Pearls plate

Full Text

References

References
1 Bardet JF, Hohn RB, Rudy RL. et al. Fractures of the humerus in dogs and cats a retrospective study of 130 cases. Vet Surg 1983; 12: 73-77.
2 Vannini R, Olmstead M, Smeak D. An epidemiological study of 151 distal humeral fractures in dogs and cats. J Am Anim Hosp Assoc 1988; 24: 531-536.
3 Guerin SR, Lewis DD, Lanz OI. et al. Comminuted supracondylar humeral fractures repaired with a modified type I external skeletal fixator construct. J Small Anim Pract 1998; 39: 525-532.
4 Kirkby KA, Lewis DD, Lafuente MP. et al. Management of humeral and femoral fractures in dogs and cats with linear- circular hybrid external skeletal fixators. J Am Anim Hosp Assoc 2008; 44: 180-197.
5 Fearnside SM, Eaton-Wells RD, Mitchel RA. Management of comminuted supracondylar fractures of the humerus with closed reduction and a hybrid type I-II external fixator. Vet Comp Orthop Traumatol 2002; 15: 233-239.
6 McKee WM, Macias C, Innes JF. Bilateral fixation of Y-T humeral condyle fractures via medial and lateral approaches in 29 dogs. J Small Anim Pract 2005; 46: 217-226.
7 Ness MG. Repair of Y-T humeral fractures in the dog using paired ‘String of Pearls' locking plates. Vet Comp Orthop Traumatol 2009; 22: 492-497.
8 Sturgeon C, Wilson AM, McGuigan P. et al. Triceps tenotomy and double plate stabilization of “Y-T” fracture of the humeral condyle in three dogs. Vet Comp Orthop Traumatol 2000; 13: 34-39.
9 Tobias KM, Johnston SA. Veterinary Surgery: Small Animal. St. Louis, Mo.: Elsevier; 2012. pg. 2012-709.
10 Frigg R. Locking Compression Plate (LCP). An osteosynthesis plate based on the Dynamic Compression Plate and the Point Contact Fixator (PC-Fix). Injury 2001; 32 Suppl 2 63-66.
11 Frigg R. Development of the Locking Compression Plate. Injury. 2003; 34 Suppl 2 B6-10.
12 Gautier E, Sommer C. Guidelines for the clinical application of the LCP. Injury 2003; 34 Suppl 2 B63-76.
13 Kraus KH, Ness MG. SOP Interlocking Plate System. Standard Operating Procedure [Company Product Information]. Version1.4. Orthomed (UK) ltd.; October 2007 [Cited on October 29, 2013]. 1-20. Available from: http://www.orthomed.co.uk/pdf-downloads.html
14 Ness MG. The effect of bending and twisting on the stiffness and strength of the 3.5 SOP implant. Vet Comp Orthop Traumatol 2009; 22: 132-136.
15 Filipowicz D, Lanz O, McLaughlin R. et al. A biomechanical comparison of 3.5 locking compression plate fixation to 3.5 limited contact dynamic compression plate fixation in a canine cadaveric distal humeral metaphyseal gap model. Vet Comp Orthop Traumatol 2009; 22: 270-277.
16 Tyler JM, Larinde W, Elder SH. A device for performing whole bone torsional testing in a single-axis linear motion testing machine. Vet Comp Orthop Traumatol 2008; 21: 478-480.
17 Seebeck J, Goldhahn J, Stadele H. et al. Effect of cortical thickness and cancellous bone density on the holding strength of internal fixator screws. J Orthop Res 2004; 22: 1237-1242.
18 Khalid M, Theivendran K, Cheema M. et al. Biomechanical comparison of pull-out force of unicortical versus bicortical screws in proximal phalanges of the hand: a human cadaveric study. Clin Biomech (Bristol, Avon) 2008; 23: 1136-1140.
19 Bockstahler B, Skalicky M, Peham C. et al. Reliability of ground reaction forces measured on a treadmill system in healthy dogs. Vet J 2007; 48: 915-918.
20 Walter R, Carrier D. Ground forces applied by galloping dogs. J Exp Biol 2007; 210: 208-216.
21 Jupiter J, Neff U, Holzach P. et al. Intercondylar fractures of the humerus. J Bone Joint Surg 1985; 67-A: 226-239.
22 Stoffel K, Cunneen S, Morgan R. et al. Comparative stability of perpendicular versus parallel double-locking plating systems in osteoporotic comminuted distal humerus fractures. J Orthop Res 2008; 26: 778-784.
23 Koonce RC, Baldini TH, Morgan SJ. Are conventional reconstruction plates equivalent to precontoured locking plates for distal humerus fracture fixation? A biomechanics cadaver study. Clin Biomech (Bristol, Avon) 2012; 27: 697-701.
24 Galano GJ, Ahmad CS, Levine WN. Current treatment strategies for bicolumnar distal humerus fractures. J Am Acad Orthop Surg 2010; 18: 20-30.
25 Nauth A, McKee MD, Ristevski B. et al. Distal humeral fractures in adults. J Bone Joint Surg Am 2011; 93: 686-700.
26 Penzkofer R, Hungerer S, Wipf F. et al. Anatomical plate configuration affects mechanical performance in distal humerus fractures. Clin Biomech (Bristol, Avon) 2010; 25: 972-978.