Problem of Pin Breakage in Equine Transfixation Pin Casting: Biomechanical Ex Vivo Testing of Four Different PinsFunding None.
26. Juni 2018
08. Januar 2019
07. März 2019 (online)
Objective The aim of this study was to evaluate cyclic fatigue behaviour of a new pin with a thread run-out design in comparison with three other types of pins commonly used for equine transfixation pin casting.
Materials and Methods Twenty-four pairs of equine cadaveric third metacarpal bones (MC3) equipped with one transfixation pin placed horizontally in the distal metaphysis were tested using a simplified model, mimicking the biomechanical situation of equine transfixation pin casting. A 6.3/8.0-mm Imex Duraface pin with thread run-out design (ITROP) was compared with a 6.1-mm smooth Steinmann pin (SSP), a Securos 6.2-mm, positive-profile pin (SPPP) and an Imex 6.3-mm, positive-profile pin (IPPP) under cyclic loading until failure in axial compression of MC3.
Results All pins broke at clinically relevant load levels and cycle numbers. The SSP endured significantly (p = 0.0025) more cycles before failure (mean: 48685) than the ITROP (mean 25889). No significant differences in cycles to failure were observed comparing the SPPP versus ITROP, and the IPPP versus ITROP, respectively.
Clinical Significance A thread run-out design does not necessarily lead to higher resistance against pin breakage under cyclic loading conditions. The SSP was most resistant against cyclic failure in these testing conditions, even though it was associated with more lateromedial displacement and cortical wear-out. This could outweigh reported disadvantages of the SSP such as reduced resistance to axial extraction and pin loosening.
Sebastian Valet and Jan M. Kümmerle contributed to conception of study, study design, acquisition of data and data analysis and interpretation. Sara A. Keller contributed to study design, acquisition of data and data analysis and interpretation. Ann Martens, Bernhard Weisse, and Anton E. Fürst contributed to conception of study, study design, and data analysis and interpretation. All authors drafted, revised and approved the submitted manuscript.
- 1 Auer JA. Principles of fracture treatment. In: Auer JA, Stick JA. , eds. Equine Surgery. 4th ed. Saint Louis, Missouri: W.B. Saunders; 2012: 1047-1081
- 2 Kraus BM, Richardson DW, Nunamaker DM, Ross MW. Management of comminuted fractures of the proximal phalanx in horses: 64 cases (1983-2001). J Am Vet Med Assoc 2004; 224 (02) 254-263
- 3 Rossignol F, Vitte A, Boening J. Use of a modified transfixation pin cast for treatment of comminuted phalangeal fractures in horses. Vet Surg 2014; 43 (01) 66-72
- 4 McClure SR, Watkins JP, Ashman RB. In vitro comparison of the effect of parallel and divergent transfixation pins on breaking strength of equine third metacarpal bones. Am J Vet Res 1994; 55 (09) 1327-1330
- 5 Joyce J, Baxter GM, Sarrafian TL, Stashak TS, Trotter G, Frisbie D. Use of transfixation pin casts to treat adult horses with comminuted phalangeal fractures: 20 cases (1993-2003). J Am Vet Med Assoc 2006; 229 (05) 725-730
- 6 Lescun TB, McClure SR, Ward MP. , et al. Evaluation of transfixation casting for treatment of third metacarpal, third metatarsal, and phalangeal fractures in horses: 37 cases (1994-2004). J Am Vet Med Assoc 2007; 230 (09) 1340-1349
- 7 Hopper SA, Schneider RK, Johnson CH, Ratzlaff MH, White KK. In vitro comparison of transfixation and standard full-limb casts for prevention of displacement of a mid-diaphyseal third metacarpal osteotomy site in horses. Am J Vet Res 2000; 61 (12) 1633-1635
- 8 Hopper SA, Schneider RK, Ratzlaff MH, White KK, Johnson CH. Effect of different full-limb casts on in vitro bone strain in the distal portion of the equine forelimb. Am J Vet Res 1998; 59 (02) 197-200
- 9 Schneider RK, Ratzlaff MC, White KK, Hopper SA. Effect of three types of half-limb casts on in vitro bone strain recorded from the third metacarpal bone and proximal phalanx in equine cadaver limbs. Am J Vet Res 1998; 59 (09) 1188-1193
- 10 McClure SR, Watkins JP, Bronson DG, Ashman RB. In vitro comparison of the standard short limb cast and three configurations of short limb transfixation casts in equine forelimbs. Am J Vet Res 1994; 55 (09) 1331-1334
- 11 Morisset S, McClure SR, Hillberry BM, Fisher KE. In vitro comparison of the use of two large-animal, centrally threaded, positive-profile transfixation pin designs in the equine third metacarpal bone. Am J Vet Res 2000; 61 (10) 1298-1303
- 12 Palmer RH, Hulse DA, Hyman WA, Palmer DR. Principles of bone healing and biomechanics of external skeletal fixation. Vet Clin North Am Small Anim Pract 1992; 22 (01) 45-68
- 13 Clary EM, Roe SC. Enhancing external skeletal fixation pin performance - consideration of the pin-bone interface. Vet Comp Orthop Traumatol 1995; 8 (01) 6-13
- 14 Anderson MA, Mann FA, Wagner-Mann C, Hahn AW, Jiang BL, Tomlinson JL. A comparison of nonthreaded, enhanced threaded, and Ellis fixation pins used in type I external skeletal fixators in dogs. Vet Surg 1993; 22 (06) 482-489
- 15 Aron DN, Toombs JP, Hollingsworth SC. Primary treatment of severe fractures by external skeletal fixation: threaded pins compared with smooth pins. J Am Anim Hosp Assoc 1986; 22 (05) 659-670
- 16 Griffin H, Toombs JP, Bronson DG, Ross JD, Browne RH. Mechanical evaluation of a tapered thread-run-out half-pin designed for external skeletal fixation in small animals. Vet Comp Orthop Traumatol 2011; 24 (04) 257-261
- 17 Keller SA. The problem of pin breakage in equine transfixation pin casting: A retrospective clinical study and biomechanical testing of four different transfixation pin designs. [Doctoral Thesis]: University of Zurich; 2018
- 18 Martens A, Pille F, Declerq J. Pin breaking as a serious complication in two cases of comminuted P1 fractures treated with transfixation-pin casting with threaded Imex pins. In: Clegg P, ed. Proceedings of 19th annual scientific ECVS meeting; Helsinki, Finland; July 1–10, 2010:157–158
- 19 Rybicki EF, Mills EJ, Turner AS, Simonen FA. In vivo and analytical studies of forces and moments in equine long bones. J Biomech 1977; 10 (11/12): 701-705
- 20 McDuffee LA, Stover SM, Coleman K. Limb loading activity of adult horses confined to box stalls in an equine hospital barn. Am J Vet Res 2000; 61 (03) 234-237
- 21 Sverdlova NS, Witzel U. Principles of determination and verification of muscle forces in the human musculoskeletal system: muscle forces to minimise bending stress. J Biomech 2010; 43 (03) 387-396
- 22 Affolter C, Müller U, Leinenbach C, Weisse B. Compressive testing of high-strength alloys. J Test Eval 2015; 43 (06) 1554-1562