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

BACKGROUND: So 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. METHOD: Freezing 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. RESULTS: Thanks 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. CONCLUSIONS: Adequate 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.