Technetium-99m-methylene diphosphonate(Tc-99m-MDP) has been widely used not only to determine the early vascular change and metabolic process but also to predict viability of the bone. There were, however, few reports which observed the early reparative process of fractures using the radioactive tracer in terms of the quantitative and qualitative measurement.
The purpose of this study is to evaluate the uptake pattern of Tc-99m-MDP at the fracture site and its adjacent bones, and also the course of healing by sequential observation of the uptake ratio of Tc-99m-MDP following fractures of long bones.
In order to study the uptake pattern and ratio of early phase of the fracture, the midshaft of the tibia of twenty mature rabbits were osteotomized intentionally and were divided into two groups; each group consisted of ten rabbits.
Group .I had external cast immobilization with no internal fixation, and group 2 had external cast immobilization with Kirschner wire fixation.
The uptake pattern and ratio of Tc-99m-MDP of the fracture site, its adjacent areas and metaphyses in each group were observed at the intervals of 6 hours, 12 hours, 1 day, 2 days, 3 days, 7 days, 14 days, 21 days and 28 days.
On the other hand, for the prospective clinical study of the uptake pattern of fractures, Tc-99m-MDP scintigraphy was carried out in seventy fracture cases, including sixteen fractures of the femoral shaft, twenty fractures of the tibial shaft, seven fractures of the humerus and forearm bone, fourteen fractures of the femoral neck and thirteen fractures of the femoral trochanter. In these cases, the uptake pattern of Tc-99m-MDP has been observed at intervals up to eighteen months after the injury.
The uptake pattern was classified in three types; proximal metaphyseal pattern, double peak pattern and single peak pattern.
The results obtained were as follows:
1. In experimental group 1, Tc-99m-MDP uptake ratio at the fracture site began to increase in 4 cases at 6 hours after the injury, and at 3rd day it increased in all to cases. In group 2, Tc-99m-MDP uptake ratio at the fracture site began to increase in 5 cases at 6
hours after the injury, and at 2nd day it increased in all 10 cases.
2. In experimental group 1 and 2, Tc-99m-MDP uptake pattern showed proximal metaphyseal pattern within 3 days, double peak pattern between 7 and 21 days. single peak pattern between 14 and 28 days, respectively.
3. In fractures of human humerus and forearm bore, double peak pattern appeared between 7 and 21 days, and single peak pattern appeared 1 month earlier than femoral and tibial fractures.
4. In fractures of human femoral neck, single peak pattern was observed in 13 cases among 14 cases within I month, but double peak pattern was not observed up to 18 months.
5. In fractures of human femoral trochanter, double peak pattern appeared between 1 and 8 months, and single peak pattern appeared at 8 months.
The results suggest that when double peak pattern of fracture site has changed into single peak pattern, we can predict the healing course in fractures before being radiologically evident and it also serves as a guide in the management of fractures.
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