Effects of antebrachial torsion on the measurement of angulation in the frontal plane: A cadaveric radiographic analysis

Summary

Objectives: To quantify the effect of antebrachial torsion on the miscalculation of radial valgus measured radiographically and to assess a radiographic positioning method used to mitigate torsion-associated artifactual miscalculation of concurrent frontal plane angulation.

Methods: A canine cadaveric forelimb was used to model different combinations of valgus and external torsion. Valgus was induced in the limb in increments of five degrees, radiographic images were taken at each increment, and the observed radiographic valgus was measured. Various angles of torsion were then induced and the process was repeated for a range of torsional angles at 15° increments. For the second objective, the study was repeated with the forelimb rotationally re-positioned to mirror the degree of the induced torsion of the deformity at each valgus and torsion iteration.

Results: Both zero degrees and 15° torsional iterations possessed mean artifactual valgus (AV) values between zero and five degrees for every valgus increment. With torsion of 30° and higher, mean AV values varied widely and did not fall within the zero to five degree accepted range. Rotationally re-positioning the limb in an attempt to alleviate the AV discrepancies resulted in the 30° torsional group having acceptable AV values for valgus values between zero and 20°.

Clinical significance: Increasing antebrachial torsion interferes with accurate radiographic measurement of frontal plane deformities. Radiographically repositioning the limb allows the accurate calculation of more valgus and torsion combinations, but still results in miscalculations of more complex deformities.

Keywords

Angular limb deformity - radioulnar torsion

• References

• 1 Johnson JA, Austin C, Breur GJ. Incidence of canine appendicular musculoskeletal disorders in 16 veterinary teaching hospitals from 1980 through 1989. Vet Comp Orthop Traumatol 1994; 7: 56-69.
• 2 Theyse LFH, Voorhout G, Hazewinkel HAW. Prognostic factors in treating antebrachial growth deformities with a lengthening procedure using a circular external skeletal fixation system in dogs. Vet Surg 2005; 34: 424-435.
• 3 Meola SD, Wheeler JL, Rist CL. Validation of a technique to assess radial torsion in the presence of procurvatum and valgus deformity using computed tomography: A cadaveric study. Vet Surg 2008; 37: 525-529.
• 4 Paley D. Rotation and Angulation-Rotation Deformities. In: Herzenberg JE. editor. Principles of Deformity Correction. 1st ed, 2nd printing. Berlin: Springer-Verlag; 2003. pg. 235-268.
• 5 Dismukes DI, Fox DB, Tomlinson JL. et al. Use of radiographic measures and three-dimensional computed tomographic imaging in surgical correction of an antebrachial deformity in a dog. J Am Vet Med Assoc 2008; 232: 68-73.
• 6 Fox DB, Tomlinson JL, Cook JL. et al. Principles of uniapical and biapical radial deformity correction using dome osteotomies and the center of rotation of angulation methodology in dogs. Vet Surg 2006; 35: 67-77.
• 7 Paley D. Hardware and Osteotomy considerations. In: Herzenberg JE. editor. Principles of Deformity Correction. 1st ed, 2nd printing. Berlin: Springer-Verlag; 2003. pg. 291-410.
• 8 Fasanella FJ, Tomlinson JL, Welihozkiy A. et al. Radiographic measurements of the axes and joint angles of the canine radius and ulna. Proceedings of the 37th Veterinary Orthopedic Society Symposium. 2010. February 20-27 Breckenridge, Colorado, USA: pg. 21.
• 9 Anderson LD, Hutchins WC, Wright PE. et al. Fractures of the tibia and fibula treated by cast and transfixation pins. Clin Orthop 1974; 105: 179-191.
• 10 Cross AR, Newell SM. Definition and determination of acetabular component orientation in cemented total hip arthroplasty. Vet Surg 2000; 29: 507-516.
• 11 Apelt D, Kowaleski MP, Dyce J. Comparison of computed tomographic and standard radiographic determination of tibial torsion in the dog. Vet Surg 2005; 34: 457-462.
• 12 Crosse KR, Worth AJ. Computer-assisted surgical correction of an antebrachial deformity in a dog. Vet Comp Orthop Traumatol 2010; 23: 354-361.