Effects of Hole Diameter on Torsional Mechanical Properties of the Rabbit Femur

Abstract

Objective The aim of this study was to evaluate and compare the effect of three clinically applicable screw hole diameters on rabbit femoral torsional structural properties.

Sample Eighteen pairs of skeletally mature New Zealand White rabbit femora (36 bones).

Materials and Methods Femora with a bicortical hole at mid-diaphysis from one of the 3-drill bit sizes, 1.1 mm, 1.5 mm, 2.0 mm, and intact bones were studied. Each bone was bi-axially loaded in a servo-hydraulic load frame with the bone positioned so the neutral axis of torsion was aligned with the centre of the bone diaphysis. Axial compression to 35% body weight was applied to represent compression at stance, and rapid external torsion was applied to failure. Torque and angular deformation data were plotted for each test, with pre-yield and post-yield stiffnesses derived. Yield and failure torques and angles were determined, along with calculated yield, failure and post-yield energies.

Results Failure torque was reduced compared with that of intact bone; weakened by 37% in 1.1-mm hole models, 53% in 1.5-mm hole models and 65% in 2.0-mm hole models. The torque angular deformation curves lacked plastic deformation.

Conclusions and Clinical Relevance This study demonstrates the unique, brittle biomechanics of rabbit bone. Based on data from other species that strength loss of no more than 50% is acceptable when placing orthopaedic implants, no defect greater than 1.1 mm (15% bone diameter) is recommended in rabbit femora.

Keywords

mechanical properties - rabbit bone - torsional properties - drill hole

Note

Supported by a grant from the Center for Companion Animal Health, School of Veterinary Medicine, University of California, Davis. This study was presented at the 2017 Surgery Summit, Indianapolis, IN.

Author Contribution

Tanya C. Garcia contributed to conception of study, study design, acquisition of data and data analysis and interpretation. Anna M. Massie contributed to study design, acquisition of data and data analysis and interpretation. Amy S. Kapatkin and Susan M. Stover contributed to conception of study, study design, and data analysis and interpretation. David Sanchez-Migallon Guzman and Po-Yen Chou contributed to study design and data analysis and interpretation. All authors drafted, revised and approved the submitted manuscript.

• References

• 1 Langley-Hobbs S, Harcourt-Brown N. Fracture management. In: Harcourt-Brown F, Chitty J. , eds. BSAVA Manual of Rabbit Surgery, Dentistry and Imaging. British Small Animal Veterinary Association Gloucester, United Kingdom; 2013: 283-304
• 2 Northrup NC, Barron GH, Aldridge CF. , et al. Outcome for client-owned domestic rabbits undergoing limb amputation: 34 cases (2000-2009). J Am Vet Med Assoc 2014; 244 (08) 950-955
• 3 Donnelly TM. Basic anatomy, physiology, and husbandry. In Hillyer EV, Quesenberry KE. , eds. Ferrets, Rabbits, and Rodents, 1st ed. Philadelphia, PA: WB Saunders; 1997: 147-159
• 4 Zehnder A, Kapatkin AS. Orthopaedics in small mammals. In Quesenberry KE, Carpenter JW. , eds. Ferrets, Rabbits, and Rodents. Clinical Medicine and Surgery. 3rd edition. St. Louis, MO: Elsevier Saunders; 2011: 472-484
• 5 Terjesen T. Bone healing after metal plate fixation and external fixation of the osteotomized rabbit tibia. Acta Orthop Scand 1984; 55 (01) 69-77
• 6 Brewer NR, Cruise LJ. Physiology. In: Manning PJ, Ringler DH, Newcomer CE. , eds. The Biology of the Laboratory Rabbit. 2nd ed. Orlando, FL: Academic Press; 1994: 63-70
• 7 Cruise LJ, Brewer NR. Anatomy. In Manning PJ, Ringler DH, Newcomer CE. , eds. The Biology of the Laboratory Rabbit. 2nd ed. Orlando, FL: Academic Press; 1994: 47-61
• 8 Neyt JG, Buckwalter JA, Carroll NC. Use of animal models in musculoskeletal research. Iowa Orthop J 1998; 18: 118-123
• 9 Gilsanz V, Roe TF, Gibbens DT. , et al. Effect of sex steroids on peak bone density of growing rabbits. Am J Physiol 1988; 255 (4 Pt 1): E416-E421
• 10 Pearce AI, Richards RG, Milz S, Schneider E, Pearce SG. Animal models for implant biomaterial research in bone: a review. Eur Cell Mater 2007; 13: 1-10
• 11 Wang X, Mabrey JD, Agrawal CM. An interspecies comparison of bone fracture properties. Biomed Mater Eng 1998; 8 (01) 1-9
• 12 Martiniaková M, Omelka R, Chrenek P. , et al. Changes of femoral bone tissue microstructure in transgenic rabbits. Folia Biol (Praha) 2005; 51 (05) 140-144
• 13 Castañeda S, Largo R, Calvo E. , et al. Bone mineral measurements of subchondral and trabecular bone in healthy and osteoporotic rabbits. Skeletal Radiol 2006; 35 (01) 34-41
• 14 Barron HW, McBride M, Martinez-Jimenez D. , et al. Comparison of two methods of long bone fracture repair in rabbits. J Exot Pet Med 2010; 19: 183-188
• 15 Hak DJ, Schulz KS, Khoie B, Hazelwood SJ. The effect of Cox-2 specific inhibition on direct fracture healing in the rabbit tibia. J Orthop Sci 2011; 16 (01) 93-98
• 16 Edgerton BC, An KN, Morrey BF. Torsional strength reduction due to cortical defects in bone. J Orthop Res 1990; 8 (06) 851-855
• 17 Gushue DL, Houck J, Lerner AL. Rabbit knee joint biomechanics: motion analysis and modeling of forces during hopping. J Orthop Res 2005; 23 (04) 735-742
• 18 Burstein AH, Frankel VH. A standard test for laboratory animal bone. J Biomech 1971; 4 (02) 155-158
• 19 Currey JD. Physical characteristics affecting the tensile failure properties of compact bone. J Biomech 1990; 23 (08) 837-844
• 20 Les CM, Stover SM, Keyak JH, Taylor KT, Kaneps AJ. Stiff and strong compressive properties are associated with brittle post-yield behavior in equine compact bone material. J Orthop Res 2002; 20 (03) 607-614
• 21 McBroom RJ, Cheal EJ, Hayes WC. Strength reductions from metastatic cortical defects in long bones. J Orthop Res 1988; 6 (03) 369-378
• 22 Burchardt H, Busbee III GA, Enneking WF. Repair of experimental autologous grafts of cortical bone. J Bone Joint Surg Am 1975; 57 (06) 814-819