Evaluation of complications of treatment of severe Blount's disease by circular external fixation using a novel classification scheme

Corrective osteotomy for recalcitrant varus deformity secondary to adolescent and infantile Blount's disease can be challenging because of a combination of severity of deformity, complexity of deformity, and frequent association with patient obesity. We present here the outcome of treatment by osteotomy and gradual deformity correction by circular external fixation in 31 patients with either infantile or adolescent Blount's disease. We used a unique classification scheme to quantify and qualify complications in this patient group: category I, complications not requiring an alteration in the treatment plan, not involving unplanned return to surgery, and not influencing outcome; category II, complications requiring an alteration in the treatment plan, including unplanned returns to surgery, but that did not influence outcome; category IIIA, complications that resulted in a failure to achieve treatment goals; and category IIIB, complications that resulted in a failure to achieve treatment goals and the development of a new pathology or worsening of patient condition. All but one patient in this group incurred at least one complication. However, despite the complex nature of this patient population, 88% achieved satisfactory correction without developing category IIIA or IIIB complications. Careful selection of patients and vigilant postoperative management can result in excellent outcomes with circular external fixation and gradual correction in this challenging patient population.