Experimental and Clinical Experience with an IM Pin External Skeletal Fixator Tie-in Configuration^[*]

Summary

An intramedullary (IM) pin external skeletal fixator “tie-in” configuration is described, for use as a stabilizing device, in the treatment of fractures of the humerus and femur in the dog and cat. With in vitro testing of the configuration using cadaver bones, more resistance to bending was gained by the tie-in arrangement than was possible with one not tied-in. Forty-one clinical cases documented the use of the tie-in configuration for fracture repair. Twenty-four dogs and 17 cats were treated over the past seven years. Fourteen were used to stabilize fractures of the humerus and 27 for the femur. Migration of the IM pin or external fixation frame was not seen and all of the cases went to bone union. The unconventional method of leaving the IM pin protruding from the skin did not lead to complications. All of the owners, contacted from one to two months after removal of the implants, reported their animals to have excellent or good results. Five animals were lost to follow-up.

Keywords

External skeletal fixation - IM pin - fracture fixation

^* Presented in part at the Annual Conference of the Veterinary Orthopaedic Society, 1990

• References

• 1 Smith GK. Biomechanics pertinent to fracture etiology, reduction, and fixation. In: Textbook of small animal orthopaedics. Newton CS, Nunamaker DM. (eds). Philadelphia: JB Lippincott; 1985: 195-230.
• 2 Rhinelander FW. Blood supply of healing long-bones. In: Textbook of small animal orthopaedics. Newton CD, Nunamaker DM. (eds). Philadelphia: JB Lippincott; 1985: 39-58.
• 3 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: 659-70..
• 4 Braden TD, Brinker WO. Effect of certain internal fixation devices on functional limb usage in dogs. J Am Vet Med Assoc 1973; 162: 642-6..
• 5 Egger EL, Rigg DL, Blass CE. et al. Type 1 biplanar configuration of external skeletal fixation. J Am Vet Med Assoc 1985; 187: 262-7..
• 6 Nunamaker DM. Methods of internal fixation. In: Textbook of small animal orthopaedics. Newton CD, Nunamaker DM. (eds). Philadelphia: JB Lippincott; 1985: 261-86.
• 7 Brinker WO, Hohn RB, Prieur WD. Manual of internal fixation in small animals. Berlin: Springer; 1984
• 8 Chao EYS, Pope MH. The mechanical basis of external fixation. In: Concepts in external fixation. Seligson D, Pope M. (eds). New York: Grune & Stratton; 1982: 13-39.
• 9 Egger EL. Static strength evaluation of six external skeletal fixation configurations. Vet Surg 1983; 12: 130-6..
• 10 Sumner-Smith G, Bishop HM. Nonunion: Pathogenesis and treatment. In: Bone in clinical orthopaedics. Sumner-Smith G. (ed). Philadelphia: WB Saunders; 1982: 399-415.
• 11 Aron DN. External Skeletal Fixation. Vet Med Rep 1989; 1: 181-201..
• 12 Egger EL, Histand MB, Nordin RW, Konde LJ. An experimental comparison of canine osteotomy healing stabilized with constantly rigid fixation against decreasingly rigid fixation. Trans Orthop Res Soc 1986; 11: 473.
• 13 Weber BG. Duration of external fixation, and removal of the external fixator. In: The external fixator. Weber BG, Magerl F. (eds). Berlin: Springer; 1985: 96-9.
• 14 Aron DN, Toombs JP. Updated principles of external skeletal fixation. Comp Cont Ed 1984; 6: 845-58..