To examine the effects on 99mTc medronate (MDP) bone scintigraphy of unilateral anterior cruciate ligament (ACL) transection in the unstable and contralateral knee of dogs.
Bone scintigraphy was performed in 5 dogs at baseline and 6 and 12 weeks after ligament transection, with images of both knees obtained 3-4 h after intravenous injection of the radionuclide. An image of the T4-T5 vertebral region was also acquired as an internal standard. In 3 additional dogs, scintigraphy was performed at baseline and 5 1/2 weeks after sham ACL transection.
A marked increase in uptake of 99mTc MDP was seen in the unstable knee. In contrast, in all but one case uptake in the contralateral knee did not increase significantly. Sham ligament transection had no effect on uptake of the radionuclide.
Changes occur in subchondral bone as well as in articular cartilage in the unstable knee in this model. The bony changes, which could be either primary or secondary to early changes in the biomechanical properties of the cartilage, may contribute to the pathogenesis of cartilage damage. No appreciable effects on bone turnover in the contralateral knee could be proved in this study.