Download PDF
Vet Comp Orthop Traumatol 2013; 26(05): 385-391
DOI: 10.3415/VCOT-12-10-0126
Original Research
Schattauer GmbH

In vitro biomechanical testing of a micro external skeletal fixator

R. Deiss
1   Veterinary Practice Kiesen, Kiesen, Switzerland
,
M. S. Bali
2   Small Animal Hospital Stommeln, Stommeln, Germany
,
M. Doherr
3   University of Bern, Veterinary Medicine, Clinical Research, Bern, Switzerland
,
D. Spreng
4   University of Bern, Small Animal Clinic, Bern, Switzerland
,
U. Rytz
4   University of Bern, Small Animal Clinic, Bern, Switzerland
,
S. J. Ferguson
5   Swiss Federal Institute of Technology Zurich (ETH), Institute for Biomechanics, Zurich, Switzerland
› Author Affiliations
Further Information

Publication History

Received 14 October 2012

Accepted 28 April 2013

Publication Date:
23 December 2017 (online)

Also available at
    Permissions and Reprints

Summary

Objective: To biomechanically test the properties of three different Universal Micro External Fixator (UMEX™) configurations with regard to their use in very small animals (<5kg) and compare the UMEX system to the widely used IMEX External Skeletal Fixation (SK™) system in terms of stiffness, space needed for pin placement and weight.

Methods: Three different UMEX configurations (type Ia, type Ib, and type II modified) and one SK configuration type Ia were used to stabilize Delrin plastic rods in a 1 cm fracture gap model. These constructs were tested in axial compression, craniocaudal bending, mediolateral bending, and torsion. Testing was conducted within the elastic range and mean stiffness in each mode was determined from the slope of the linear portion of the load-deformation curve. A Kruskal Wallis one-way analysis of variance on ranks test was utilized to assess differences between constructs (p <0.05).

Results: The UMEX type II modified configuration was significantly stiffer than the other UMEX configurations and the SK type Ia, except in craniocaudal bending, where the SK type Ia configuration was stiffer than all UMEX constructs. The UMEX type Ia configuration was significantly the weakest of those frames. The UMEX constructs were lighter and smaller than the SK, thus facilitating closer pin placement.

Conclusions: Results supported previous reports concerning the superiority of more complex constructs regarding stiffness. The UMEX system appears to be a valid alternative for the treatment of long-bone fractures in very small animals.

Keywords

External skeletal fixation - frame configuration - close pin placement - miniature dogs - cats

 

  • References

  • 1 Chao YSE, Aro HT, Lewallen DG. et al. The effect of rigidity on fracture healing in external fixation. Clin Orthop Relat Res 1989; 143: 25-35.
    PubMedGoogle Scholar
  • 2 Lappin MR, Aron DN, Herron HL. et al. Fractures of the radius and ulna in the dog. J Am Anim Hosp Assoc 1982; 19: 643-650.
    PubMedGoogle Scholar
  • 3 Egger EL, Histand MB, Norrdin RW. et al. Canine osteotomy healing when stabilized with decreasingly rigid fixation compared to constantly rigid fixation. Vet Comp Orthop Traumatol 1993; 6: 182-187.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 4 Toombs JP, Bronson DG, Ross D. et al. The SK TM external fixation system: description of components, instrumentation, and application techniques. Vet Comp Orthop Traumatol 2003; 16: 76-81.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 5 Muir P. Distal Antebrachial fractures in toy-breed dogs. The Compendium 1997; 19: 137-145.
    PubMedGoogle Scholar
  • 6 Larsen LJ, Roush JK, McLaughlin RM. Bone plate fixation of distal radius and ulna fractures in small- and miniature-breed dogs. J Am Anim Hosp Assoc 1999; 35: 243-250.
    CrossrefPubMedGoogle Scholar
  • 7 Waters DJ, Breur GJ, Toombs JP. Treatment of common forelimb fractures in miniature- and toy breed dogs. J Am Anim Hosp Assoc 1993; 29: 442-448.
    PubMedGoogle Scholar
  • 8 Lincoln JD. Treatment of open, delayed union, and nonunion fractures with external skeletal fixation. Vet Clin N Am Small 1995; 22: 195-207.
    PubMedGoogle Scholar
  • 9 Laverty PH, Johnson AL, Toombs JP. et al. Simple and multiple fractures of the radius treated with an external fixator. Vet Comp Orthop Traumatol 2002; 15: 97-103.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 10 Welch JA, Boudriaeu RJ, DeJardin LM. et al. The intraosseous blood supply of the canine radius: implications for healing of distal fractures in small dogs. Vet Surg 1997; 26: 57-61.
    CrossrefPubMedGoogle Scholar
  • 11 Wilson JW. Vascular supply to normal bone and healing fractures. Semin Vet Med Surg (Small Animal) 1991; 6: 26-38.
    PubMedGoogle Scholar
  • 12 Dugat D, Rochat M, Ritchey J. et al. Quantitative analysis of the intramedullary arterial blood supply of the feline tibia. Vet Comp Orthop Traumatol 2011; 24: 313-319.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 13 Langley-Hobbs SJ, Carmicheal S, McCartney WT. External skeletal fixation for stabilisation of comminuted humeral fractures in cats. J Small Anim Pract 1997; 38: 280-285.
    CrossrefPubMedGoogle Scholar
  • 14 Dudley M, Johnson AL, Olmstead M. et al. Open reduction and bone plate stabilization, compared with closed reduction and external fixation, for treatment of comminuted tibial fractures: 47 cases (1980-1995) in dogs. J Am Vet Med Ass 1997; 211: 1008-1012.
    PubMedGoogle Scholar
  • 15 Haas B. Use of the tubular external fixator in the treatment of distal radial and ulnar fractures in small dogs and cats. Vet Comp Orthop Traumatol 2003; 16: 132-137.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 16 Piras L, Cappellari F, Peirone B. et al. Treatment of fractures of the distal radius and ulna in toy breed dogs with circular external skeletal fixation: a retrospective study. Vet Comp Orthop Traumatol 2011; 3: 228-235.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 17 Eger CE. A technique for the management of radial and ulnar fractures in miniature dogs using transfixation pins. J Small Anim Pract 1990; 31: 377-387.
    CrossrefPubMedGoogle Scholar
  • 18 Voss K, Kull MA, Heassig M. et al. Repair of long-bone fractures in cats and small dogs with the unilock mandible locking plate system. Vet Comp Orthop Traumatol 2009; 22: 398-405.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 19 Johnson AL, Kneller AK, Weigel RM. Radial and tibial fracture repair with external skeletal fixation. Vet Surg 1989; 18: 367-372.
    CrossrefPubMedGoogle Scholar
  • 20 Hamilton MH, Langley Hobbs SJ. Use of the AO veterinary mini ‘T’-plate for stabilisation of distal radius and ulna fractures in toy breed dogs. Vet Comp Orthop Traumatol 2005; 18: 18-25.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 21 Diaz-Bertrana MC, Durall I, Puchol JL. et al. Interlocking nail treatment for long-bone fractures in cats: 33 cases (1995-2004). Vet Comp Orthop Traumatol 2005; 18: 119-126.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 22 Altunatmaz K, Ozsoy S, Mutlu Z. et al. Use of intramedullary fully-threaded pins in the fixation of feline and canine humeral, femoral and tibial fractures. Vet Comp Orthop Traumatol 2012; 25: 321-325.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 23 Shahar R. Relative stiffness and stress of type I and type II external fixators: acrylic versus stainless-steel connecting bars-a theoretical approach. Vet Surg 2000; 29: 59-69.
    CrossrefPubMedGoogle Scholar
  • 24 Kenwright J, Goodship AE. Controlled mechanical stimulation in the treatment of tibial fractures. Clin Orthop Relat R 1989; 241: 36-47.
    PubMedGoogle Scholar
  • 25 Claes LE, Wilke HJ, Augat P. et al. Effect of dynamization on gap healing of diaphyseal fractures under external fixation. Clin Biomech 1995; 10: 227-234.
    CrossrefPubMedGoogle Scholar
  • 26 Kawoosa AA, Dhar SA, Mir MR. et al. Distraction osteogenesis for ulnar lengthening in Kienbock`s disease. Int Orthop 2007; 31: 339-344.
    CrossrefPubMedGoogle Scholar
  • 27 Rumph PF, Kincaid SA, Visco DM. et al. Redistribution of vertical ground reaction force in dogs with experimentally induced chronic hindlimb lameness. Vet Surg 1995; 24: 384-389.
    CrossrefPubMedGoogle Scholar
  • 28 Rumph PF, Lander JE, Kincaid SA. et al. Ground reaction force profiles from force platform gait analyses of clinically normal mesomorphic dogs at the trot. Am J Vet Res 1994; 55: 756-761.
    PubMedGoogle Scholar
  • 29 Bronson DG, Ross JD, Toombs JP. et al. Influence of the connecting rod on the biomechanical properties of five external skeletal fixation configurations. Vet Comp Orthop Traumatol 2003; 16: 82-87.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 30 White DT. A mechanical comparison of veterinary linear external fixation systems. Vet Surg 2003; 32: 507-514.
    CrossrefPubMedGoogle Scholar
  • 31 Bouvy BM, Markel MD, Chelikani S. et al. Ex vivo biomechanics of Kirschner-Ehmer external skeletal fixation applied to canine tibiae. Vet Surg 1993; 22: 194-207.
    CrossrefPubMedGoogle Scholar
  • 32 Reaugh HF, Rochat MC, Bruce CW. et al. Stiffness of modified Type 1a linear external skeletal fixators. Vet Comp Orthop Traumatol 2007; 20: 264-268.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 33 Muir P, Johnson KA, Markel MD. Area moment of inertia for comparison of implant cross-sectional geometry and bending stiffness. Vet Comp Orthop Traumatol 1995; 8: 146-152.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 34 O´Doherty DM. Stress protection due to external fixation. J Biomech 1995; 28: 575-586.
    CrossrefPubMedGoogle Scholar
  • 35 DeAngelis MP, Old RB, Stoll SG. et al. Repair of fractures of the radius and ulna in small Dogs. J Am Anim Hos Assoc 1973; 9: 436-441.
    PubMedGoogle Scholar
  • 36 Silva HR, Clements DN, Yeadon R. et al. Linear-circular external skeletal fixation of intra-condylar humeral fractures with supracondylar comminution in four cats. Vet Comp Orthop Traumatol 2012; 25: 61-66.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 37 Worth AJ. Management of fractures of the long bones of eight cats using external skeletal fixation and a tied-in intra-medullary pin with a resin-acrylic bar. N Z Vet J 2007; 55: 191-197.
    CrossrefPubMedGoogle Scholar
  • 38 Ross JT, Matthiesen DT. The use of multiple pin and methylmethacrylate external skeletal fixation for the treatment of orthopaedic injuries in the dog and cat. Vet Comp Orthop Traumatol 1993; 6: 115-121.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 39 Yu J, DeCamp CE, Rooks R. Improving surgical reduction in radial fractures using a ‘dowel’ pinning technique in miniature and toy breed dogs. Vet Comp Orthop Traumatol 2011; 24: 45-49.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 40 Shani J, Shahar R. The unilateral external fixator and acrylic connecting bar, combined with I.M pin, for the treatment of tibial fractures. Vet Comp Orthop Traumatol 2002; 15: 104-110.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 41 Willer RL, Egger EL, Histand MB. Comparison of stainless steel versus acrylic for the connecting bar of external skeletal fixators. J Am Anim Hosp Assoc 1991; 27: 541-548.
    PubMedGoogle Scholar
  • 42 Staudte KL, Gibson NR, Read RA. Evaluation of a metal acrylic repair product as a clamp for an external fixator. Vet Comp Orthop Traumatol 2004; 17: 97-103.
    Article in Thieme ConnectPubMedGoogle Scholar
  • 43 Bennett RA, Egger EL, Histand M. et al. Comparison of the strength and holding power of 4 pin designs for use with half pin (type I) external skeletal fixation. Vet Surg 1987; 16: 207-211.
    CrossrefPubMedGoogle Scholar
  • 44 Anderson MA, Mann FA, Wagner-Mann C. et al. A Comparison of nonthreaded, enhanced threaded, and Ellis fixation pins used in type 1 external skeletal fixators in dogs. Vet Surg 1987; 16: 207-211.
    CrossrefPubMedGoogle Scholar