Blood supply and structural changes of canine intact tibia following plate fixation with different rigidities

To study the causes of osteopenia after plate fixation in the treatment of fractures and bone diseases, intact tibiae of 26 dogs were fixed by 3 different plates at various rigidities. The dogs were killed at 24 hours 3, 6, 12, 20 weeks. Disulphine blue was injected intravenously before killing. The results showed that in addition to stress shielding the disturbance of blood supply was the main cause of osteopenia in the early stage. Reaction to the implant might be another cause in the middle stage. The disuse of the affected limb was the most important factor in the late stage. Osteopenia can be treated by active exercises and normal weight-bearing before plate removal.