In Vivo Measurement of Tension in the Rabbit Patellar Tendon.

Tension developing in the right and left patellar tendon was measured in vivo with a buckle transducer in six rabbits. Peak tension measured during normal running was quite large and ranged from 44 N to 123 N, which is from 130% to 380% of body weight. Maximum load of the whole patellar tendon, which is the failure load determined from tensile testing, was 799±40 N (Mean±S. E.) : it is 7 to 18 times as much as the in vivo peak tension. Right patellar tendons of the other eight rabbits were over. stressed by decreasing the cross-sectional area by about 50% by partial cut-removal of both sides of the tendon. After this surgical treatment, these rabbits were allowed their daily activities in cages for 3 or 6 weeks. Tension developed in the patellar tendon was measured in vivo using the buckle transducer. There were no significant differences in the tension developed in the tendon inside the body between the treated and intact knees, which indicated that the stress applied to the tendon was increased to about 200% by the treatment of partial cut-removal.