PubMed2000
This study was conducted in order to determine the values of forces necessary to stretch bony fragments during tibia lengthening in rabbits. The aim of this study was to determine the conditions which lead to complications of the lengthening process related to the rate of distraction. The experiment was conducted on 16 rabbits of New Zealand breed. The construction of the apparatus eliminated tension resulting from the so-called "bending moment". In all rabbits distraction was began on the 5th day after fixing the apparatus. The standard rate of lengthening was 2 x 0.25 mm per day. In 8 rabbits the rate of distraction was regulated. The distraction forces were measured and electronically recorded during the distraction procedure, during the animal's movement and resting position at strictly monitored intervals. Radiological examination of the lengthened tibia was performed once a week. Histological examination was performed in three rabbits after completion of the experiment. We made 328 measurements of the involved distractive forces, collecting a total of 223 MB of data. Graphical representation of the lengthening force and it's performance turned out to be similar for various experimental animals and it's course was typical for every stage of the lengthening process. At the time of distraction of the apparatus the measured force increased on average by 0.87 N (minimum 0.61, maximum 1.1N). Abnormal rates of distraction resulted in a break of the callus continuity in 3 rabbits. Radiological and histological examinations were used to assess to confirm certain observations concerning the technique and rate of distraction.