Canine pubic symphysiodesis: Investigation of electrocautery dose responseby histologic examination and temperature measurement

Objectives-To determine thermal necrosis zone and the maximal temperature a chieved with various electrocautery doses applied to the pubic symphysis of immature dogs, and to establish the minimal electrocautery dose needed to affect thermal necrosis of the germinal chondrocytes of the immature canine pubis. Study Design-A randomized, controlled, prospective study. Animals-Twelve puppies, 15 to 17 weeks of age. Methods-Each treated puppy was randomly selected to receive 3 of 33 possibl e doses of electrical current applied at uniform intervals along the pelvic symphysis. Three treatment sites were sham-operated controls. All treatmen t zones were biopsied 7 days after application of electrocautery. Confocal laser microscopy with calcein green and ethidium homodimer red stains were used to determine cell type and viability within treatment and control zone s. The physeal diameter and thermal necrosis zone were measured. Thermal ne crosis zone and dose, and temperature and dose were compared using regressi on analysis. Prediction equation analysis was used to establish dose recomm endations. Results-Doses of 40 W produced a highly significant linear relationship (R- 2 = .88, P < .01) with thermal necrosis zone, and a significant linear rela tionship (R-2 = .76, P < .02) with maximal temperature. Conclusions-The thermal necrosis zone within the pelvic symphysis and maxim al temperature achieved can be reliably predicted using electrocautery dose s of 40 W. For application of electrocautery to induce pubic symphysiodesis , doses should be chosen based on measured or estimated physeal size. Using prediction equation analysis, the surgeon can plan mean thermal necrosis z one with acceptable variance. Clinical Relevance-Unipolar needle electrocautery can be used to reliably a chieve symphyseal necrosis. Prediction equation analysis can be used to det ermine 40-W doses. (C) Copyright 2001 by The American College of Veterinary Surgeons.