Pe. Greis et al., The influence of tendon length and fit on the strength of a tendon-bone tunnel complex - A biomechanical and histologic study in the dog, AM J SP MED, 29(4), 2001, pp. 493-497
Using a dog model, we examined the influence of tendon length and fit withi
n a bone tunnel on the pullout strength of a tendon-bone tunnel complex at
6 weeks after fixation. Fourteen adult mongrel dogs (weight, 25 to 30 kg) u
nderwent bilateral hindlimb surgery in which the extensor digitorum longus
tendon was transplanted into an extraarticular metaphyseal bone tunnel. Our
findings demonstrated that pull-out strength at 6 weeks was enhanced by in
creasing the length of tendon within the tunnel. The average load to failur
e with 1 cm of tendon within the tunnel was 153.7 +/- 78.6 N, compared with
265.5 +/- 93.3 N for the specimens with 2 cm of tendon in the tunnel. Tend
on fit within the tunnel was also found to be important. The average load t
o failure when a tendon was placed in a 4.2-mm diameter tunnel was 301 +/-
61 N at 6 weeks. The average load to failure when the tendon was placed wit
hin a 6-mm diameter tunnel was 228 +/- 65 N. These differences were statist
ically different. Histologically, the interface between the tendon and bone
appeared to be most mature when there was intimate bone-to-tendon contact.
These data suggest that maximizing tendon length within a bone tunnel and
minimizing tendon-tunnel diameter mismatch will maximize the strength of a
tendon-bone tunnel complex at 6 weeks.