Design and evaluation of a cryogenic soft tissue fixation device - load tolerances and thermal aspects

Mechanical studies of soft connective tissues often encounter methodologica l difficulties, particularly in the secure fixation of the tissues. A simpl e, inexpensive technique which allowed stable cryofixation of soft tissues in uniaxial loading machines was developed. The cryogenic fixation device w as evaluated in terms of its fixation strength and the temperature gradient s within the tested tissues. Human patellar ligaments and quadriceps tendon s were tested successfully to an average failure load of 2219 N (S.D. 448 N ) with mid-substance failures occurring in 90% of the specimens. The temper ature gradients within porcine flexor and extensor tendons were determined and found to exhibit a typical diffusion profile. The fixation quality was dependent upon the initial block temperature and the desired testing time. In summary, the cryofixation device presented here is an effective tool for soft tissue fixation but the effect of this type of fixation on internal t issue temperatures and possible testing times must be acknowledged. (C) 200 1 Elsevier Science Ltd. All rights reserved.