Zielke instrumentation in idiopathic scoliosis: late effects and minimizing complications.

Sixty-eight patients with idiopathic scoliosis treated with Zielke instrumentation are reviewed. Comparison of Groups A and B demonstrates a statistically significant reduction in the incidence of rod fracture by modifying preoperative selection criteria and operative technique as described. Only one-half of the cases with broken implants had an unfavorable clinical course, and those rod fractures with curve progression were associated with significant pain. Average kyphosis was 9.7 degrees, and did not correlate with the subjective result. Analysis of Group A showed that thoracic progression was rare, and tended to occur in patients who were out of balance. Seventy-two percent of patients operated on for severe pain report significant relief at 4.2 years average follow-up, many reporting continued improvement between 1 and 3 years after surgery.