FACTORS AFFECTING NEW BONE-FORMATION BY C ALLUS DISTRACTION OF ILIZAROV

We evaluated the X-rays of 36 patients who underwent 50 callus distrac tions. With the aid of a computerized digitalisation system for analog ue films, the relative X-ray density of the distraction area was calcu lated for each X-ray. These relative X-ray densities were figured grap hically for the duration of treatment for each patient. In the consoli dation phase, the graph of each patient had a logarithmic relationship . The gradients of the logarithmic density curves were considered an i ndicator of the quantity of new bone formation. These gradients were c orrelated to the following clinical parameters: age of the patient, be ginning of distraction after corticotomy, average speed of distraction , average weight bearing during the distraction and consolidation phas e, location of corticotomy (distal femur versus proximal tibia) and di clofenac medication. Except for the location of the corticotomy and di clofenac, all parameters had an influence on osteoneogenesis by callus distraction. The parameters affecting new bone formation the most wer e the age of the patient and weight bearing. Patients aged under 18 ye ars (p=0.005), beginning of distraction later than 8 days (p=0.109), a n average distraction speed below 1 mm/day (p=0.079), and average weig ht bearing of more than 30 kg (p=0.068 for the distraction phase and p =0.089 for the consolidation phase) showed a quantitatively higher rat e of new bone formation by callus distraction than the patients in the other groups. Patients with a shorter leg due to poliomyelitis and on e patient with an amniotic leg tie showed a slower increase in X-ray d ensity graphs than the other patients.