Cryosurgery in long bones with new miniature cryoprobe: an experimental in vivo study of the cryosurgical temperature field in sheep

Aim: The aim of this in vivo study was to determine whether new miniature cryoprobes provide adequate tissue cooling in long bones by measuring the field of temperature under various conditions. Methods: Freezings were performed in femoral and tibial bones of 10 sheep under general anaesthesia. Applying one cryoprobe, temperatures of −75°C resp. −51°C could be reached within 0.75 cm resp. 1.00 cm of the probe. Results: Histological examinations revealed compact bone and marrow necroses along the isotherm in all 10 sheep. Using two cryoprobes simultaneously, a mean temperature decrease to −71°C between the two cryoprobes was achieved thanks to the synergistic freezing effect. Looking at consecutive freezes, it was apparent that with similar cryoprobe end temperatures, the temperature dropped faster if the number of freezing cycles was increased. Conclusion: In conclusion, it was seen that despite its small diameter, the new miniature cryoprobe delivers adequate in vivo tissue cooling in long tubular bones. Employing the synergistic freezing effect by using two or more cryoprobes simultaneously, efficient in vivo freezing of larger bone segments is also possible. Thus, cryosurgery with the new miniature probes can provide a valuable complement to conventional resection of long tubular bones, and offers a viable alternative to surgical treatment of neoplastic diseases of the skeletal system.