Blood flow in rat gastrocnemius muscle and Achilles tendon after Achilles tenotomy.

The effect of Achilles tenotomy on resting blood flow of rat gastrocnemius muscle and Achilles tendon was studied by radioactive microspheres. Tenotomy produced an immediate, marked decrease in both intramuscular and intratendinous blood flow and it remained significantly lowered at both sites till the end of the observation period, i.e., day 18 after tenotomy. The decrease in the resting blood flow was more rapid and pronounced in the Achilles tendon than in the gastrocnemius muscle. Although the blood flow of the Achilles tendon started to recover after the 4th postoperative day, it was still 33% (statistically not significant) lower than that in the controls 18 days after tenotomy. In the gastrocnemius muscle, the 18-day deficit was 38% (p < 0.001), respectively. The results indicate that after division of a rat Achilles tendon the resting blood flow to the gastrocnemius muscle and Achilles tendon is not adequately restored, remaining at a significantly lowered level even 18 days after tenotomy.