The use of a new miniature cryoprobe for ablation of bone tissue: In vivo assessment of the probe and application of the method to bone in a sheep model

Abstract

BackgroundSo far, modern miniature cryoprobes were used for local destruction of soft tissue tumours without damaging the adjacent healthy tissue. In this study, cryoablation methodology was applied to bone and the cooling capacity of the probe was examined in vitro and in vivo.MethodFreezing was performed by cooling one or two probes (diameter 3.2 mm) to -180°C with liquid nitrogen. The cooling capacity of the probes was determined optically and thermally against a homogeneous reference gel, followed by in vivo measurements on femoral and tibial sheep bone followed by histological examination.ResultsThanks to the synergistic effect, the simultaneous use of 2 probes produced an almost spherical expansion of cold in the homogenous gelatin. During the in vivo freezes, the temperature curves showed a more moderate trend. Nevertheless, due to the synergistic effect, temperatures below -50°C could be reached at a distance of 1 cm from the probe. No local or systemic intraoperative complications were observed. Histological examination revealed cell necrosis up into the -10°C isotherm.ConclusionsAdequate tissue cooling of the bone matrix can be achieved with in vivo freezes by means of one or more miniature cryoprobes. Therefore, this probe could provide an alternative to or supplement surgical resection of pathological bone processes.

Temperature Isotherms during Pulmonary Cryoablation and their Correlation with the Zone of Ablation

“…The ablation zones were consistent and reproducible with a close relationship identified between the −20°C isotherm and the zone of coagulative necrosis. This finding is in agreement with that of previous studies, which have found that the critical isotherm is between −20 and −40°C depending on the tissue type (15,17). Also, the results show that clinically relevant ablation zone sizes can be achieved in the lung with percutaneous cryoprobes.…”

Changes in morphology of long bone marrow tissue of rats submitted to cryotherapy with liquid nitrogen

“…In this study we observed no pathological fracture, even in the group two weeks of both protocols, where was observed the peaks of medullar inflammation, and corroborated by other studies such as those made by Kuylenstierna et al 10,11 and Popken et al 13 . …”

Experimental cryosurgery investigations in vivo

“…However the strength of the bone was weakened by the process of resorption, so fractures were common in this weight-bearing bone about three months after freezing. Popken et al used miniature cryoprobes cooled by liquid nitrogen to produce freezing in the tibia and femur of sheep [162,163]. The probe temperature was −180°C.…”