Thermal Bone Necrosis Research Articles

In vivo reduction of biofilm seeded on orthopaedic implants.

Electromagnetic induction heating has demonstrated in vitro antibacterial efficacy over biofilms on metallic biomaterials, although no in vivo studies have been published. Assessment of side effects, including thermal necrosis of adjacent tissue, would determine transferability into clinical practice. Our goal was to assess bone necrosis and antibacterial efficacy of induction heating on biofilm-infected implants in an in vivo setting. Titanium-aluminium-vanadium (Ti6Al4V) screws were implanted in medial condyle of New Zealand giant rabbit knee. Study intervention consisted of induction heating of the screw head up to 70°C for 3.5 minutes after implantation using a portable device. Both knees were implanted, and induction heating was applied unilaterally keeping contralateral knee as paired control. Sterile screws were implanted in six rabbits, while the other six received screws coated with Staphylococcus aureus biofilm. Sacrifice and sample collection were performed 24, 48, or 96 hours postoperatively. Retrieved screws were sonicated, and adhered bacteria were estimated via drop-plate. Width of bone necrosis in retrieved femora was assessed through microscopic examination. Analysis was performed using non-parametric tests with significance fixed at p ≤ 0.05. The width of necrosis margin in induction heating-treated knees ranged from 0 to 650 μm in the sterile-screw group, and 0 to 517 μm in the biofilm-infected group. No significant differences were found between paired knees. In rabbits implanted with sterile screws, no bacteria were detected. In rabbits implanted with infected screws, a significant bacterial load reduction with median 0.75 Log10 colony-forming units/ml was observed (p = 0.016). Induction heating was not associated with any demonstrable thermal bone necrosis in our rabbit knee model, and might reduce bacterial load in S. aureus biofilms on Ti6Al4V implants.

Supervised Machine Learning to Predict Drilling Temperature of Bone

Surgeons face a significant challenge due to the heat generated during drilling, as excessive temperatures at the bone–tool interface can lead to irreversible damage to the regenerative soft tissue and result in thermal osteonecrosis. While previous studies have explored the use of machine learning to predict the temperature rise during bone drilling, this in vitro study introduces a comprehensive approach by combining the Response Surface Methodology (RSM) with advanced machine learning techniques. The main objective lies in the comprehensive evaluation and comparison of support vector machine (SVM) and random forest (RF) models specifically for the optimization of the bone drilling parameters to prevent thermal bone necrosis. A total of 27 experiments were conducted using a multi-level factorial method, with analysis performed via the Minitab software version 19.1. Performance metrics such as the mean squared error (MSE), mean absolute percentage error (MAPE), and coefficient of determination (R2) were used to assess model accuracy. The RF model emerged as the most effective, with R2 values of 94.2% for testing and 97.3% for training data, significantly outperforming other models in predicting temperature fluctuations. This study demonstrates the superior predictive capabilities of the RF model and offers a robust framework for the optimization of surgical procedures to mitigate the risk of thermal damage.

Heat Generation and Risk of Thermal Necrosis during Minimally Invasive Hallux Valgus Correction Utilizing a Shannon Burr: A Cadaveric Study

Category: Midfoot/Forefoot; Other Introduction/Purpose: Minimally invasive (MIS) bunion correction is growing in popularity as a treatment option of hallux valgus deformities. This technique has been shown to help with post-operative pain and improve functional outcomes. Despite these benefits there are concerns that the Shannon burr may lead to excess heat generation, thermal necrosis of bone and potentially increase the risk of nonunion. The purpose of our study was to assess the heat generation while using a Shannon burr during MIS first metatarsal osteotomies. Methods: Four below knee cadavers were utilized and osteotomies of the distal and proximal aspects of each of the first metatarsal were performed utilizing a 2mm x 20mm Shannon burr under fluoroscopic guidance. 3 K-type thermocouples were placed in each metatarsal, one distal, one in between and one proximal to the osteotomy sites. Temperatures were evaluated during the entire burring process and after to assess heat dissipation and total heat generated. Three different techniques of burring were utilized, 1. Continuous without irrigation, 2. Continuous with irrigation and 3. Pulse burring technique with irrigation (20 seconds on, 10 seconds off). Results: The pulse burring technique with irrigation showed the overall lowest max temperature and change in temperature compared to the other techniques. Average burr time, maximum heat generation and overall change in heat was 86.2 seconds, 102.4 °F and 78.9 °F for all trials. Conclusion: The pulse burr technique with irrigation generated less heat than both continuous burring with and without irrigation. There was an overall trend toward higher heat generation with longer burr times regardless of irrigation and burring technique. Utilizing a Shannon burr with pulse burring and irrigation can minimize heat generation and potentially decrease the risk of thermal necrosis of bone.

Heat Accumulation in Implant Inter-Osteotomy Areas-An Experimental In Vitro Study.

To examine the influence of the distance between adjacent implant osteotomies on heat accumulation in the inter-osteotomy area, two experimental groups with 15 pairs of osteotomies in Type II polyurethane blocks were compared: 7 mm inter-osteotomy separations (Group A, n = 15) and 14 mm inter-osteotomy separations (Group B, n = 15). An infrared thermographic analysis of thermal changes in the inter-osteotomy area was completed. A one-way analysis of variance (ANOVA) and Fisher post-test were used to determine group differences. Higher temperatures were recorded in Group A at the coronal and middle levels compared to the apical level in both groups. The temperature reached max temperatures at T80s and T100s. In Group A, the threshold for thermal necrosis was exceeded. Meanwhile, Group B did not reach the threshold for thermal necrosis. Preparing adjacent implant osteotomies in dense bone with a 7 mm separation between their centers increases the temperature in the inter-osteotomy area, exceeding the threshold for bone thermal necrosis; meanwhile, increasing the distance between osteotomies reduces the thermal accumulation and the risk for thermal necrosis.

Better Wielding the Electric Drill

one is a dense, mineral-rich tissue with organic components. Implants such as plates and nails are used to reconstruct fractures. Various types of drills are used in orthopedic surgery, ranging from pneumatic and battery-operated to electric devices, each of which has its own set of benefits and drawbacks. Standard care is generally achievable through orthopedic battery-operated and pneumatic drills, which are costly and have high maintenance costs. So, orthopedic surgeons frequently employ alternatives such as the Bosch battery drill, and a corded electric drill is generally used in developing nations. These drills are inexpensive, but they cannot be used for reaming. Furthermore, some models of these drills have a constant speed, making them difficult to be utilized for reaming. We offered modifications to this type of drill to control its speed, so it can be used for reaming. There is abundant evidence dismissing misconceptions such as electric drills’ overheating and subsequently leading to bone thermal necrosis. There are multiple scientifically documented methods to effectively sterilize an electric drill. Due to its affordability and ease of maintenance, our innovations, such as speed control and drill cannulation, enable us to adopt this device for most traumatic surgeries, particularly in developing nations.

The electric drill to better use

Bone is a dense, mineral-rich tissue with organic components. Implants such as plates and nails are used to reconstruct fractures. In orthopedic surgery, broad-spectrum of drills ranges from pneumatic to battery-operated to electric drills. Each drill has its own set of benefits and drawbacks.Though the standard of care, the orthopedic battery drill, and pneumatic drills are costly, the expense of maintenance is too high. Orthopedic surgeons frequently employ alternatives such as the Bosch battery drill and a corded electric drill in developing nations. These drills are inexpensive, but they cannot be used for reaming. Furthermore, some models have a constant speed, making them difficult to utilize for reaming.We offer drill modifications to control the speed and use it for reaming. The literature has abundant evidence to dismiss misconceptions concerning electric drill overheating and bone thermal necrosis. There are multiple scientifically documented methods for effectively sterilizing an electric drill. Due to its affordability and ease of maintenance, our innovations, such as speed control and drill cannulation, enable us to adopt it for most trauma surgeries, particularly in developing nations.

The Effect of Chilled vs Room Temperature Irrigation on Thermal Energy Dissipation During MIS Calcaneal Osteotomy

Category: Hindfoot; Basic Sciences/Biologics; Other Introduction/Purpose: Minimally Invasive (MIS) calcaneal osteotomy has grown in popularity in recent years to address hindfoot deformity. A potential complication is thermal bone necrosis secondary to heat generation from the burr, leading to nonunion of the osteotomy. Irrigation is commonly employed to reduce this risk. The effect of irrigation on reducing this risk remains an understudied area. The purpose of this study was to evaluate the effect of cooled versus room-temperature irrigation on thermal energy dissipation on a temperature curve during calcaneal osteotomy using a Shannon burr. Methods: Ten cadaveric limbs (5 pairs) at room temperature (68 0F) were randomized to receive either cooled saline or room temperature irrigation during MIS calcaneal osteotomy. Two thermocouple probes (EL-USB-TC-LCD, Lascar Electronics) were inserted 5mm away from the plane of the osteotomy, on proximal and distal sides respectively (Fig. 1). The probes were inserted to a depth of 2cm. A 3 x 30mm Shannon burr was used to perform the osteotomy. The burr was run continuously under continuous irrigation using either room temperature (680F) and chilled (370F) irrigation, until the osteotomy was completed. All osteotomies were performed in approximately 60 seconds. Temperature was recorded at 15sec, 30sec, 45 sec and 60 sec for the two groups and used as a measure of thermal energy generation. Results: Both room temperature and chilled irrigation were effective in minimizing temperature change. On the proximal side, an overall mean increase of 2.60F (70.60F) with room temperature irrigation and a mean increase of 0.70F (68.70F) with chilled irrigation were observed at the 60 sec interval (p=0.09). On the distal side both irrigation methods were more effective in heat control (70.20F vs 67.10F; p=0.17). Conclusion: For the duration of a MIS calcaneal osteotomy, both continuous room temperature and chilled irrigation can reduce thermal energy generation. Use of chilled irrigation can be considered for osteotomies of denser bone that may take longer to perform and generate higher temperatures.

The Effect of Chilled vs Room-Temperature Irrigation on Thermal Energy Dissipation During Minimally Invasive Calcaneal Osteotomy of Cadaver Specimens.

Minimally invasive (MIS) calcaneal osteotomy has grown in popularity in recent years to address hindfoot deformity. A potential complication is thermal bone necrosis secondary to heat generation from the burr that may lead to osteotomy nonunion. Irrigation is commonly employed to reduce this risk. The effect of irrigation on reducing heat accumulation remains an understudied area. The purpose of this study was to evaluate the effect of cooled vs room-temperature irrigation on thermal energy dissipation during calcaneal osteotomy using a Shannon burr. Fourteen cadaveric limbs at room temperature (68 °F) were randomized to receive either cooled saline (7 limbs) or room-temperature (7 limbs) irrigation during MIS calcaneal osteotomy. Two thermocouple probes were inserted 5 mm away from the plane of the osteotomy, on the proximal and distal sides, respectively. A 3 × 30-mm Shannon burr was used to perform the osteotomy. The burr was run continuously with continuous irrigation using either room-temperature (68 °F) or chilled (37 °F) irrigation, until the osteotomy was completed. Temperature was recorded at 0, 15, 30, 45, and 60 seconds for the 2 groups and used as a measure of thermal energy accumulation. Both room-temperature and chilled irrigation were effective in minimizing temperature change. On the proximal side, an overall mean increase of 2.5 °F with room-temperature irrigation and a mean decrease of 1.0 °F with chilled irrigation were observed at the 60-second interval (P = .004). On the distal side, there was a mean increase of 1.3 °F with room-temperature irrigation and a mean increase of 0.5 °F with chilled irrigation (P = .05). For the duration of an MIS calcaneal osteotomy, both continuous room-temperature and chilled irrigation can minimize temperature increases and potentially reduce the risk of an osteotomy nonunion. Both room-temperature and chilled irrigation can minimize bone temperature increases during MIS calcaneal osteotomy.

Bone grinding using coarse-grained diamond wheels to suppress thermal damage

Bones, which are hard tissues in the human body, are frequently removed during spine, joint, and brain surgeries. Diamond grinding wheels are widely used for the careful removal of bones during surgeries such as an endoscopic surgery. However, the wheels generate a considerable amount of heat, causing thermal damage, such as thermal bone necrosis and thermal injury to adjacent tissues. Considerable research has been conducted to suppress this heat generation using #120–#200 (grit size) wheels; notably, #30–#120 wheels are often used in actual surgeries to reduce the operating time. In this study, the bone grinding characteristics associated with a temperature increase were studied when using a coarse-grained wheel, i.e., a #30 wheel. Results showed that the temperature increased owing to the large grain size of the wheel. Furthermore, a decrease in the rotation speed of the wheel effectively suppressed the temperature increase. Consequently, an increase in the grain depth of cut and a decrease in the generated frictional heat between bone and grains effectively suppressed the temperature increase.

Effect of Guiding Sleeve Design on Intraosseous Heat Generation During Implant Site Preparation (In Vitro Study).

To compare the effect of different designs of guiding sleeves on heat generation during implant surgery while using different cooling fluid temperatures. Temperature measurements were performed during guided implant site preparation in bovine rib samples using two K- type thermocouples at 2 mm and 8 mm depths. Three groups were tested according to guiding sleeve design: conventional cylindrical sleeve, open C-shaped sleeve, and modified cylindrical sleeve. Each group was irrigated with three fluid temperatures: 10°C, 15°C, and 20°C. The groups were compared using Kruskal Wallis test followed by post hoc comparisons with Bonferroni correction. The level of statistical significance was set at p = 0.05. Surgical guides with conventional cylindrical sleeve design showed significantly higher heat generation during implant site preparation than guides with both the open C-shaped and the modified cylindrical sleeve designs at both 2mm and 8mm depths. The difference between C-shaped and modified cylindrical sleeves was not significant in any group. Using pre-cooled irrigation fluids (10°C and 15°C) reduced the generated heat; however, the differences within the same group were not statistically significant. The use of a surgical guide with the conventional cylindrical sleeves led to higher heat generation than other sleeve designs, which might reach or near the critical threshold of bone thermal necrosis. Using surgical guides with open sleeves or modified cylindrical sleeves could be helpful in irrigation fluid delivery and decreasing the generated heat.

Temperature Threshold Values of Bone Necrosis for Thermo-Explantation of Dental Implants-A Systematic Review on Preclinical In Vivo Research.

Purpose: Very high or low temperatures will lead to bone damage. The objective of this review was to analyze threshold values for thermal bone necrosis. Methods: Histological animal studies evaluating thermal effects on bone necrosis were selected via electronic and hand searches in English and German language journals until 1 November 2019. The outcome measures were temperature-exposure intervals and laser settings effecting bone damage. Furthermore, investigated parameters were the bone-to-implant contact ratios (BIC) and infrabony pockets around dental implants after thermal treatment. For quality assessment of studies, the CAMARADES study quality checklist was applied. Results: A total of 455 animals in 25 animal studies were included for data extraction after screening of 45 titles from 957 selected titles of the MEDLINE (PubMed), The Cochrane Library, Embase and Web of Science search. The threshold values for bone necrosis ranged between 47 °C and 55 °C for 1 min. A threshold value for cryoinsult and laser treatment has not yet been defined. However, temperatures in the vicinity of 3.5 °C produce a histologically proven effect on the bone and in the surrounding tissue. At 50 °C for 1 min, BIC values significantly decreased and infrabony pockets increased. Bone quality had an influence on the outcome, as cancellous bone suffered higher bone damage from thermal treatment compared to cortical bone. Conclusion: No clear threshold value for bone necrosis is available according to the current literature for warm and cold stimuli. More in-depth and clinical studies are required to provide further insights in assessing the potential of thermal necrosis for implant removal.

The effect of spatial distances between holes and time delays between bone drillings based on examination of heat accumulation and risk of bone thermal necrosis

Background and objectiveThis study was designed to investigate heat accumulation and bone thermal necrosis for various distances between holes and time delays between drillings.MethodsThe tests were performed at three distances (6, 12, 16 mm) and three time delays: 0, 5 and 10 s. To examine the efficiency of coolants, CO2 coolant was also tested in addition to two common cooling modes in bone drilling.ResultsThe main results were the trend of temperature–time graph, maximum temperature at drilling site, temperature distribution on the surface of drilling site, temperature durability and returning time. The effect of lateral drillings on the initial hole was notable in drilling at a distance of 6 mm without cooling. This effect did not disappear even by increasing the time delay up to 10 s. The results obtained for drilling with normal saline coolant were not sufficiently acceptable due to the manual and non-uniform cooling process as well as the relative obstruction of the chips exit path. Generally, drillings with two common cooling modes, even when the distances between holes and time delays between drillings were controlled, did not yield all favorable conditions for preventing bone thermal necrosis.ConclusionBone drilling using CO2 coolant eliminates the risk of bone thermal necrosis completely even in cases that the distances between holes in plates or implants are 6 mm and there is no time delay between drillings. These results can be especially useful in emergency orthopedic surgeries and for designing the location of screw holes in implants and plates.

Osteotomy speed, heat development, and bone structure influence by various piezoelectric systems-an in vitro study.

The aim of this in vitro study was to evaluate osteotomy speed, heat development, and bone structure influence from osteotomies performed by various piezoelectric devices and insert tips. These devices and tips were compared among each other with regard to conventional rotatory and oscillating systems with special focus on the insert tip design and thickness. The osteotomies were conducted on porcine ribs utilizing 12 different insert tips (straight and angulated) and three conventional systems. After time and temperature measurements, histological analysis was carried out. Light microscopy was used to evaluate the roughness of the osteotomic surface and to search for indications of thermal bone necrosis. A special software analyzing tool was employed to determine cutting width (mm) and debris (%). All piezoelectric tips created smooth cuts. Cutting widths in general were wider than the actual insert tip size with a tendency for narrow straight insert tips producing relatively wide osteotomies, whereas narrow angulated inserts produced relatively small osteotomies. None of the samples demonstrated distinct indication of necrosis. Overall, there was only a small amount of debris in all osteotomy gaps. Conventional rotatory saws were faster and created less heat compared to all tested piezoelectric systems. Straight tips proved faster osteotomy speed than angulated tips. Thin insert tips indicated to have a positive correlation to osteotomy time and performed faster than conventional microsaw. The average temperature rise was lower when using conventional systems, but critical exceeding temperatures were only observed in short-time exceptional cases. In general, temperature rise was less when using angulated inserts. All tested tips are appropriate for bone surgery. Only small differences were found among the piezoelectric insert tips. Although conventional rotatory systems in general performed faster osteotomies, special designed and thin piezoelectric insert tips seem to have a positive influence on osteotomy speed. Ultimately, none of the tested devices or inserts combined all best features of speed, heat development, bone structure influence, and safety. Narrow and straight piezoelectric insert tips demonstrated reduced osteotomy times. Nevertheless, a combination of conventional and piezoelectric systems in clinical practice might be the best way to work time-efficient, patient-oriented, and safe. The choice of instrument should be based on clinical experience of the user and should be evaluated individually depending on the case.

Optimization of drilling parameters for thermal bone necrosis prevention.

Bone drilling is a mandatory process in orthopedic surgery to fix the fractured bones. Excessive heat is generated due to the shear deformation of bone and friction energy during the drilling process. This paper is carried out to optimize the bone drilling parameters to prevent thermal bone necrosis. The main contribution of this work is instead of only consider the influence of rotational speed and feed rate, the effect of tool diameter and drilling hole depth are also incorporated for optimization study. Response surface methodology (RSM) was used to develop a temperature prediction model. Drilling experiments were performed using finite element software DEFORM-3D. Analysis of variance (ANOVA) was conducted to investigate the drilling parameters' effect. Desirability function in RSM was used to determine the optimum combination of drilling parameters. Results indicated that one applicable combination of drilling parameters could increase the bone temperature by less than 0.03%. To avoid thermal bone necrosis, eight reasonable combinations of drilling parameters were proposed. 3.3∘C residuals between in-vitro experiments and predicted values were demonstrated. It is envisaged that finite element simulation with RSM can simplify tedious experimental works and useful in the clinical application to avoid bone necrosis.

The thermal conductivity of cortical and cancellous bone.

Surgical interventions close to vulnerable structures, such as nerves, require precise handling of surgical instruments and tools. These tools not only pose the risk of mechanical damage to soft tissues, but they also generate heat, which can lead to thermal necrosis of bone or soft tissues. Researchers and engineers are trying to improve those tools through experimentation and simulations. To simulate temperature distributions in anatomical structures, reliable material constants are needed. Therefore, this study aimed at investigating the thermal conductivity of cortical and cancellous bone. Accordingly, a custom-made steady-state experimental setup was designed and validated. 6 bovine and 3 human cortical bone samples, as well as 32 bovine cancellous bone samples, with variable bone volume fraction were tested. The cancellous bone samples were scanned by micro-computed tomography (µCT) and micro-finite element (µFE) voxel models were created to calculate iteratively the thermal conductivity of the bone marrow. The experimental results provided 0.64 ± 0.04 W/mK for bovine cortical bone and 0.68 ± 0.01 W/mK for human cortical bone. A linear dependency of thermal conductivity on bone volume fraction was found for cancellous bone [R-square (R2) = 0.8096, standard error of the estimates (SEE) = 0.0355 W/mK]. The thermal conductivity of the bone marrow was estimated to be 0.42 ± 0.05 W/mK. These results will help to improve thermal finite element simulations of the human skeleton and aid the development of new surgical tools or procedures.

Unicortical self-drilling external fixator pins reduce thermal effects during pin insertion

IntroductionExternal fixation is associated with the risk of pin loosening and pin infection potentially associated to thermal bone necrosis during pin insertion.ObjectiveThis study aims to investigate if the use of external fixator systems with unicortical pins reduces the heat production during pin insertion compared to fixators with bicortical pins.MethodsPorcine bone specimens were employed to determine bone temperatures during insertion of fixator pins. Two thermographic cameras were used for a simultaneous temperature measurement on the bone surface (top view) and a bone cross-section (front view). Self-drilling unicortical and bicortical pins were inserted at different rotational speeds: (30–600) rpm. Maximum and mean temperatures of the emerging bone debris, bone surface and bone cross-section were analyzed.ResultsMaximum temperatures of up to 77 ± 26 °C were measured during pin insertion in the emerging debris and up to 42 ± 2 °C on the bone surface. Temperatures of the emerging debris increased with increasing rotational speeds. Bicortical pin insertion generated significantly higher temperatures at low insertion speed (30 rpm)ConclusionThe insertion of external fixator pins can generate a considerable amount of heat around the pins, primarily emerging from bone debris and at higher insertion speeds. Our findings suggest that unicortical, self-drilling fixator pins have a decreased risk for thermal damage, both to the surrounding tissue and to the bone itself.

Increased wound complication with intramedullary screw fixation of clavicle fractures: Is it thermal necrosis?

Adult mid-shaft clavicle fractures are common injuries. For displaced fractures, open reduction with plate or intramedullary (IM) fixation is the widely used techniques. All methods have their own potential drawbacks, especially related to local soft tissue complications. There is little information about outcome and management of local wound complications after clavicle fracture fixations. Ninety-seven patients underwent open reduction and internal fixation, 17 were treated with IM screw fixation and 80 with plate fixation. Wound complication occurred in eight patients (8.2%) and rates differed significantly between IM and plate fixations (29.4% vs. 3.8%). Patients were assessed on average 58.3 months with visual analogue pain scores (VASs), Oxford Shoulder Score (OSS), and QuickDash (QD) score. Five patients had wound breakdown and three patients had wound erythema. In seven patients with stable fixation, it was possible to "dress and suppress" with average 3 weeks of oral antibiotics. One patient had unstable fixation and required longer antibiotic treatment with early screw removal. One patient developed a chronic discharging wound, requiring debridement and later plate removal. At final follow-up, all wounds remained healed, bony union was achieved in all. The average scores were: VAS 1, OSS 46, and QD 4.5. Good function with dry healed wound and united clavicle can be achieved. Further studies are required to investigate the difference in soft tissue complication rates, which may be due to the IM technique of retrograde drilling with a guide wire and due to aseptic thermal bone necrosis, rather than true infection.

Real-Time Prediction of Temperature Elevation During Robotic Bone Drilling Using the Torque Signal.

Bone drilling is a surgical procedure commonly required in many surgical fields, particularly orthopedics, dentistry and head and neck surgeries. While the long-term effects of thermal bone necrosis are unknown, the thermal damage to nerves in spinal or otolaryngological surgeries might lead to partial paralysis. Previous models to predict the temperature elevation have been suggested, but were not validated or have the disadvantages of computation time and complexity which does not allow real time predictions. Within this study, an analytical temperature prediction model is proposed which uses the torque signal of the drilling process to model the heat production of the drill bit. A simple Green's disk source function is used to solve the three dimensional heat equation along the drilling axis. Additionally, an extensive experimental study was carried out to validate the model. A custom CNC-setup with a load cell and a thermal camera was used to measure the axial drilling torque and force as well as temperature elevations. Bones with different sets of bone volume fraction were drilled with two drill bits ([Formula: see text]1.8 mm and [Formula: see text]2.5 mm) and repeated eight times. The model was calibrated with 5 of 40 measurements and successfully validated with the rest of the data ([Formula: see text]C). It was also found that the temperature elevation can be predicted using only the torque signal of the drilling process. In the future, the model could be used to monitor and control the drilling process of surgeries close to vulnerable structures.

Effect of surgical drill guide and irrigans temperature on thermal bone changes during drilling implant sites - thermographic analysis on bovine ribs.

During drilling implant sites, mechanical energy is converted into thermal one resulting in transient rise in temperature of surrounding bone. The temperature of 47°C exeeding one minute impairs osseointegration, compromises mechanical properties of the local bone and could cause early implant failure. This in vitro study aimed to assess the effect of surgical drill guide and temperature of irrigans on thermal changes of the local bone during drilling implant sites, and to test the influence of irrigans temperature on the temperature of surgical drill guide. A total of 48 specimens obtained from bovine ribs were randomly allocated to four experimental conditions according to the 2 x 2 factorial design: drill guide (with or without) and saline (at 25°C or 5°C). Real-time infrared thermography was used as a method for temperature measurement. The primary outcome was bone temperature change during drilling implant sites measured at 3 osteotomy depths, whereas the second one was change in the temperature of the drill guide. Data were analyzed by Brunner and Langer nonparametric analysis and Wilcoxon test. The effect of drill guide on the changes of bone temperature was significant at the entrance of osteotomy, whereas the effect of saline temperature was significant at all osteotomy levels (p < 0.001). No significant interaction was found (p > 0.05). Guided surgery and irrigation with saline at 25°C were associated with the highest bone temperature increase. Increase in drill guide temperature was significantly higher when saline at 25°C was used (p < 0.001). Guided implant site preparation generates higher temperature of the local bone than conventional drilling, not exceeding the threshold for thermal bone necrosis. Although saline at room temperature provides sufficient heat control during drilling, cooled saline is more effective regardless the use of surgical drill guide.

Subaquatic reaming during arthrodesis of the first metatarsophalangeal joint to prevent thermal necrosis of bone.

When performing fusions of the first metatarsophalangeal joint, it has been hypothesized that the use of a cup and cone reamer may cause thermal necrosis, leading to potential nonunion. The friction created by the reamer spinning against the bone has been shown to cause elevations of temperatures capable of causing thermal necrosis. Failing to cool the bony-reamer interface, or doing so inadequately with a bulb syringe, increases the patient's odds of experiencing a nonunion. The authors describe a simple technique that prevents significant temperature elevations at the reamer-bony interface, decreasing the potential for thermal necrosis and increasing the likelihood of successful fusion. The authors have performed this procedure for several patients without complications.