The effects of Stimbone-1, a complex of growth factors deposited by osteal tissue, on maturation of distraction regenerative substrate are studied in dogs. At the end of distraction, the preparation is injected into the regenerative connective tissue interlayer. Roentgenological, biochemical, and quantitative morphological data show that Stimbone-1 stimulates reparative osteogenesis. Key Words: growth factors; d&traction osteosynthesis; reparative osteogenesisShortening of medical treatment of orthopedic patients is an important problem. Elongation of extremities and repair of the tubular bone defects by perosseal osteosynthesis according to Ilizarov requires more than half of the treatment period for maturation and mineralization of the osteal regenerative substrate obtained by distraction [7]. A new preparation was developed in our Center, which is a complex of growth-regulating noncollagenous proteins of mature osteal tissue [2]. Previously, we reported that systemic administration of this preparation modifies reparative osteogenesis [3]. In this work we examined the effects of this preparation named Stimbone-1 on maturation of the distraction osteal regenerative substrate (DORS) after local administration into the connective tissue interlayer that separates the ossified subdivisions of the regenerative substance. MATERIALS AND METHODSExperiments were carried out on 24 adult mongrel dogs subjected to distraction of the tibia using the G. A. Ilizarov Russian Research Center for Reparative Traumatology and Orthopedics, Kurgem Ilizarov apparatus. "Severe" conditions for distraction osteosynthesis were created to reduce osteosynthetic activity and to provide the background against which preparation could exhibit the highest activity. To this end transverse osteotomy was performed in the median third of the tibia with cutting the bone marrow and intraoste'al vessels. Distraction was started 3 days after operation at a late of 1 ram/day (4 times by 0.25 lnm) and stopped after 28 days. During the first 3-4 days of fixation, the preparation (2 ml) was injected into the median interlayer of regenerative substrate. Control dogs received 0.15 M NaCI (2 ~N). During the 28-day distraction period and 6-and 12-week frxation periods, the activity of osteogenesis was estimated by roentgenological data: size of DORS cross-section, height of the connective tissue interlayer, its crossing and replacelnent by trabecular ghosts, formation of cortical plate (CP) and bone marrow lumen (BML), by optical density, and using a 5-point scale.The animals were euthanized 6 or 12 weeks after fixation. DORS were divided into two parts in the sagittal plane. The lateral half was studied by biochemical methods [4] with determination of collagen, noncollagen protein, calcium, and nonorganic phos-

Two types of growth factors were used in an attempt to improve the quality of the regenerate bone in canine tibias after Ilizarov lengthening. Mechanical testing, biochemical analysis and histology did not demonstrate appreciable differences between the treated and the control limbs.