Biomedical subjects
R E Leggon
Publications and source records attributed to R E Leggon.
Strength reduction and the effects of treatment of long bones with diaphyseal defects involving 50% of the cortex.
Currently, three criteria are accepted as indications for prophylactic internal fixation of metastatic disease in long bone, including lesions (a) destroying 50% or more of the cortex; (b) 2.5 cm or greater in diameter; or (c) with pain unrelieved by radiation therapy. Using an oblong defect configuration in which one half of the cross-sectional area was destroyed, canine femora were torsion-tested at high speed to determine (a) the actual strength reduction incurred by a lesion destroying 50% of the cortical circumference, and (b) the effects and benefits of internal fixation using polymethylmethacrylate and/or a six-hole compression plate on such a defect. The femurs with a 50% circumferential cortical defect demonstrated only 12.7 +/- 3.8% of intact strength. Defects treated with a combination of plating (all screws bicortical) and polymethylmethacrylate (torque to failure 4.39 +/- 0.90 times greater than the defect alone or TE/TD = 4.39 +/- 0.90) were statistically stronger than defects treated with polymethylmethacrylate alone (TE/TD = 2.48 +/- 0.66; p less than 0.025) or by plating alone (TE/TD = 2.61 +/- 0.91; p less than 0.025), but torque-to-failure was only increased to approximately 56% of an intact bone. Plated intact bones (TE/TD = 5.33 +/- 0.41) were significantly weaker than intact bones (TE/TD = 8.50 +/- 2.52; p less than 0.001). Our results substantiate the need for using polymethylmethacrylate and internal fixation in combination when prophylactically fixing pathologic lesions of this proportion.
Separation of the symphysis pubis in association with childbearing. A case report.
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Effects of bone graft and electrical stimulation on the strength of healing bony defects in dogs.
Autogenous cancellous bone graft alone or in combination with electrical stimulation is commonly employed yet there exists no conclusive data that the strength of the healing defect is actually modified. The authors examined three groups of paired canine femurs that were torsion tested to failure. Group I (in vitro): an intact femur was compared to a standard defect; Group II (in vivo): a defect alone was compared to a defect plus graft killed at eight weeks; Group III (in vivo): a defect plus graft was compared to a defect graft plus Osteostim (BGS Medical Corp., Milwaukee, Wisconsin) implantable stimulator killed at eight weeks. In Group I the defect decreased the average strength 45% (p = 0.005); in Group II the grafted defect decreased the strength 20% (p = 0.121); in Group III the defect graft plus electrical stimulation increased strength 4% (p = 0.669). At eight weeks, bone grafting, alone or with electrical stimulation did not statistically increase the torsional strength of the healing bony defect.