## 6 Cooling Methods and Their Effects on PMMA Bone Cement Properties
have shown that this method has a significant effect and can be effective in mitigating thermal damage when utilizing PMMA bone cement [39; 47; 48]. Other attempts have been made to utilize heat sinks inside the joint cavity, like irrigation with cooled liquid, during cementing. This can reduce the temperature peak of the polymerization reaction, but it also extends the handling time of the cement [49]. Utilizing bone cement with a modified composition, such as with added castor oil or nanoparticles, can result in decreased exothermic temperatures. These changes also have a tendency to extend the handling time of the cement, but do have an effect in reducing the temperature values of the exothermic reaction [50; 51]. Submerging the PMMA bone cement in an ice bath prior to mixing reduces the temperature values but significantly extends the handling time. This effect can be a desirable one, particularly during surgical interventions such as vertebplasty [46] (Table 2). Cooling PMMA bone cement during its polymerization reaction affects the mechanical properties and handling characteristics of the cement. These may be desirable effects, such as extending the handling time, a useful feature during procedures like vertebplasty, as it permits a more controlled manipulation of the cement [46]. Pre-cooled PMMA has a reduced peak temperature during polymerization, and the time necessary to achieve this peak is extended; these two factors decrease the risk of thermal damage occurring in the adjacent bone tissue [52; 53]. The mechanical properties of pre-cooled cement, such as density, modulus, and compressive strength, are not significantly affected compared to a control group [53; 54]. Another characteristic of the cement is affected by cooling is its porosity. Lower peak temperatures may be preferable for reducing the risk of thermal necrosis, but they can lead to increased porosity at the implant-cement interface, compromising the implant's longevity. This is particularly true for low-viscosity-type PMMA bone cement [54]. The choice of PMMA bone cement, according to its viscosity, significantly impacts the surgical outcome of the orthopedic procedure because of its effects on healing, the setting time of the cement, and the characteristics of the polymerization reaction. Viscosity is a key factor when it comes to the injectability of the cement during stabilizing procedures such as vertebplasty and kyrophplasty. Lower viscosity bone cement is easier to handle and insert into its final location but presents a higher risk for extravasation. Higher viscosity bone cement has a significantly lower handling time and requires more precise handling, but the risk of extravasation is considerably lower [55,56]. Lower viscosity bone cements are easier to inject but have a higher risk for extravasation, while higher viscosity bone cements are safer to use but have significantly lower handling times and require more precise handling, but are easier to handle [53,54]. Pre-cooling and using ice baths may extend the handling time of high-viscosity bone cement while also lowering the peak temperature values, but this can lead to increased microporosity at the implant-cement interface, increasing the risk of implant failure. Controlling the handling time is important during orthopedic surgery to prevent premature setting [53,55]. Adding castor oil or other such modifiers can further adjust the viscosity of the bone cement and the characteristics of the polymerization reaction and enhance the handling capability safety of the cement while also lowering the peak temperatures of the polymerization reaction [50]. Understanding these prospects can help optimize the surgical outcome of these procedures, balancing ease of use with safety and effectiveness [42,53,55] (Table 3). The exothermic polymerization reaction of PMMA bone cement leads to the thermal necrosis of adjacent tissues and compromises long-term outcomes. To address these issues, various modifications to bone cement formulations and techniques have been investigated.