Holding Power of 3.5 mm Versus 4.0 mm Screw Applications Placed in Stripped 2.7 mm Screw Sites

Summary

Mechanical stripping of orthopaedic screws is a complication that can occur during plate fixation of fractures. This report compares the holding power of 3.5 mm cortical and 4.0 mm cancellous orthopaedic screws inserted as a salvage technique in stripped 2.7 mm screw sites in cadaver bone. Both 3.5 mm and 4.0 mm orthopaedic screws were applied with and without tapping to stripped screw sites in the diaphysis of mature canine tibiae. Mechanical testing of the pull-out force required to extract these screws showed that all of the applications have comparative holding powers, but the 4.0 mm screw had significantly greater holding power when compared with the 3.5 mm screw. Tapping the stripped screw site, prior to placing the 3.5 mm or 4.0 mm screw, did not significantly affect the holding power. The 4.0 mm cancellous screw has the advantages of significantly greater holding power and less interference with the 2.7 mm dynamic compression plate, when compared to the 3.5 mm cortical screw.

The holding power of 3.5 mm cortical and 4.0 mm cancellous orthopaedic screws placed tapped and untapped into 2.7 mm stripped screw sites in post-mortem canine tibiae were compared. All applications had comparable holding power, but with the 4.0 mm screw the holding power was significantly greater. Tapping stripped screw sites did not have any significant effect on holding power.

Keywords

Canine - screws - holding power - screw stripping - fracture repair

• REFERENCES

• 1 Nunamaker D, Perren S. Force measurements in screw fixation. J Biomechan 1976; 9: 669-75.
• 2 Schatzker J, Home JG, Sumner-Smith G. The effect of movement on the holding power of screws in bone. Clin Orthop Rel Res 1975; 3: 258-62.
• 3 Korvick DL, Monville JD, Pijanowski GJ. et al. The effects of screw removal on bone strain in an idealized plated bone model. Vet Surg 1988; 17: 111-6.
• 4 Fitch R, Oliver J, Kerwin S. et al. In vitro microscopic evaluation of orthopaedic screw sites stripped with a 2.7 mm screw, before and after application of a 3.5 mm cortical and 4.0 mm cancellous screw applied tapped and untapped. Vet Comp Orthop Traumatol 1998. (Submitted)
• 5 Klause SE, Gustafson SB, Blackketter DM. et al. Holding strength of 4.5 mm cortical screws in polymethyl methacrylate filled medullary cavities of canine bone. Vet Comp Orthop Traumatol 1992; 5: 109-13.
• 6 Texhammar R, Colton C. AO/ASIF Instruments and implants: A technical manual. 2nd ed. New York: Springer Verlag; 1994
• 7 DeCoster TA, Heetderks DB, Downey DJ. et al. Optimizing bone screw pullout force. J Orthop Trauma 1990; 4: 169-74.
• 8 Kirpensteijn J, St Jean G, Roush JK. et al. Holding power of orthopaedic screws in metacarpal and metatarsal bones of young calves. Vet Comp Orthop Traumatol 1992; 5: 100-3.
• 9 Sardinas JC, Kraus KH, Sisson R. Comparison of the holding power of 3.5 mm cortical versus 4.0 mm cancellous orthopaedic screws in the pelvis of immature dogs (cadavers). Am J Vet Res 1995; 56: 248-51.
• 10 Yovich JV, Turner AS, Smith FW. Holding power of orthopaedic screws in equine third metacarpal and metatarsal bones, Part II. Adult Horse Bone. Vet Surg 1985; 14: 230-4.
• 11 Yovich JV, Turner AS, Smith FW. Holding power of orthopaedic screws in equine third metacarpal and metatarsal bones, Part I. Foal bone. Vet Surg 1985; 14 (03) 221-9.
• 12 Yovich JV, Turner AS, Smith FW. Holding power of orthopaedic screws; comparison of self-tapped and pre-tapped screws in foal bones. Vet Surg 1986; 15 (01) 55-9.
• 13 Hearn T, Surowiak J, Schatzker J. Effects of tapping on the holding strength of cancellous bone screws. Vet Comp Orthop Traumatol 1992; 5: 10-2.
• 14 Markel M, Seilman E, Rapoff A. et al. Mechanical properties of long bones in dogs. Am J Vet Res 1994; 55 (08) 1178-83.
• 15 Boyd CL, Bynum D, Ray DR. et al. In vitro evaluation of bone fasteners. Southwestern Vet 1970; 23: 279-81.
• 16 Gantous A, Phillips JH. The effects of varying pilot hole size on the holding power of miniscrews and microscrews. Plast Reconstr Surg 1995; 1165-9.
• 17 Chapman JR, Harrington RM, Lee LM. et al. Factors affecting the pullout strength of cancellous bone screws. J Biomech Eng 1996; 118 (03) 391-8.
• 18 Hughes AN, Jordan BA. The mechanical properties of surgical bone screws and some aspects of insertion practice. Injury. British J Accident Surg 1972; 4: 25-38.
• 19 Bahr W. Comparison of torque measurements between cortical screws and emergency replacement screws in the cadaver mandible. J Oral Maxillofac Surg 1992; 50 (01) 46-9.
• 20 Hunt CA, Litsky AS. Stabilization of canine pelvic osteotomies with AO/ASIF plates and screws. Vet Comp Orthop Traumatol 1988; 1: 52-7.
• 21 Ronderos JF, Jacobowitz R, Sonntag VK. et al. Comparative pull-out strength of tapped and untapped pilot holes for bicortical anterior cervical screws. Spine 1997; 22 (02) 167-70.
• 22 Muller M, Allgower M, Schneider R. et al. Manual of internal fixation: Techniques recommended by the AO-ASIF Group. 3rd ed. New York: Springer Verlag; 1991
• 23 Fitch R, Kerwin S. Unpublished data from sixteen 2.7 mm screw pull-outs trials in mature canine tibiae. 1997
• 24 Boyle JM, Frost DE, Foley WL. et al. Evaluation of emergency screws in nonstripped pilot holes in bone. Int J Adult Orthod Orthognath Surg 1993; 8: 211-5.
• 25 Boyle JM, Frost DE, Foley DE. et al. Torque and pullout analysis of six currently available self-tapping and "emergency" screws. J Oral Maxillofac Surg 1993; (51) 45-50.