Thermal Conductivity of Human Bone in Cryoprobe Freezing as Related to Density

Intraoperative Cryotherapy in the Treatment of Metastatic Renal Cell Carcinoma of the Bone

Osseous metastases in renal cell carcinoma (RCC) are a heterogeneous mix of cells with hypervascular and rapidly destructive properties that frequently exhibit resistance to both radiation and chemotherapy. Despite this, some patients with isolated and oligometastatic disease have the potential to be cured. Regardless, aggressive metastatic control is critical to minimizing morbidity and mortality for all patients with metastatic RCC. Percutaneous cryoprobes were developed as a minimally invasive technique for both pain relief and tumor control. However, there is little evidence describing an alternative use of this technology in the operating room to assist with open tumor resections, and no formal role for its use in orthopedics exists. Therefore, the authors added this modality to their intraoperative treatment of osseous RCC to investigate whether it would influence their ability to obtain local metastatic control. The authors performed a retrospective chart review of prospectively obtained data to evaluate the role of intraoperative cryotherapy in the treatment of osseous RCC. From 2004 to 2017, cryotherapy was used in 43 procedures, alleviating the need for additional radiation 84% (36 of 43) of the time. Local tumor control was achieved in 100% (43 of 43) of cases. There were 2 wound-related complications and 1 pathologic fracture. Despite the study's limitations, the authors believe that cryotherapy contributed to the reliability and reproducibility of their intralesional resections. Given the palliative, and potentially curative, opportunities afforded by complete locoregional tumor control, the authors support further investigation into the use of intraoperative cryotherapy to treat osseous metastases secondary to RCC. [Orthopedics. 2021;44(5):e645-e652.].

Heat analysis of different devices for thermo-explantation of dental implants: a numeric analysis and preclinical in-vitro model

Thermal treatment may reverse the osseointegration of implants and could become an atraumatic controlled method for implant removal in the future. The aim of this non-random in vitro study was to empirically identify suitable sources for a controlled heating process, in order to generate a homogenous temperature distribution at a threshold level of 47°C for future in vivo research. Two different set-ups evaluating four different sources (water, laser, monopolar and an electrical joule heater device) were used to carry out infrared measurements and numerical calculations at 47°C along the implant axis and along the periimplant area at the axial plane. Furthermore, required time intervals to heat up the implant tip from 33°C to 47°C were determined. The monopolar electric device led to the most uneven and unpredictable implant heating and was therefore excluded. The thermal analysis suggested identical thermal distributions without any significant differences for water and electrical joule sources with a heat maximum at the implant shoulder (p > 0.05). On the other hand, the laser device may produce the temperature maximum in the middle of the implant without any afterglow effect (p < 0.01). When the implant was heated from 33°C up to 47°C, the water device indicated the fastest approach. Thermal distributions of water and laser sources may be suitable for clinical applications. For future research the numerical analysis may suggests an ideal time interval of 120s to 180s for a homogenous implant temperature of 47°C.

Influence of ageing on human body blood flow and heat transfer: A detailed computational modelling study

Ageing plays a fundamental role in arterial blood transport and heat transfer within a human body. The aim of this work is to provide a comprehensive methodology, based on biomechanical considerations, for modelling arterial flow and energy exchange mechanisms in the body accounting for age-induced changes. The study outlines a framework for age-related modifications within several interlinked subsystems, which include arterial stiffening, heart contractility variations, tissue volume and property changes, and thermoregulatory system deterioration. Some of the proposed age-dependent governing equations are directly extrapolated from experimental data sets. The computational framework is demonstrated through numerical experiments, which show the impact of such age-related changes on arterial blood pressure, local temperature distribution, and global body thermal response. The proposed numerical experiments show that the age-related changes in arterial convection do not significantly affect the tissue temperature distribution. Results also highlight age-related effects on the sweating mechanism, which lead to a significant reduction in heat dissipation and a subsequent rise in skin and core temperatures.