Experimental investigation and statistical modeling of temperature rise in rotary ultrasonic bone drilling

Soft material drilling: A thermo-mechanical analysis of polyurethane foam for biomimetic bone scaffolds and optimization of process parameters using Taguchi method

Drilling is a widely employed technique in machining processes, crucial for efficient material removal. However, when applied to living tissues, its invasiveness must be carefully considered. This study investigates drilling processes on polyurethane foam blocks mimicking human bone mechanical properties. Various drill bit types (118° twist, 135° twist, spherical, and conical), drilling speeds (1000-1600 rpm), and feed rates (20-80 mm/min) were examined to assess temperature elevation during drilling. The Taguchi method facilitated systematic experiment design and optimization. Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) identified significant drilling parameters affecting temperature rise. Validation was conducted through confirmation testing. Results indicate that standard twist drill bits with smaller point angles, lower drilling speeds, and higher feed rates effectively minimize temperature elevation during drilling.

Experimental investigation on punch shear strength of poly lactic acid specimens for biomedical applications

The designed biomedical implants require excellent shear strength primarily for mechanical stability against forces in human body. However, metallic implants undergo stress shielding with release of toxic ions in the body. Thus, Fused Deposition Modeling (FDM) has made significant progress in the biomedical field through the production of customized implants. The mechanical behavior is highly dependent on printing parameters, however, the effect of these parameters on punch shear strength of ASTM D732-02 standard specimens has not been explored. Thus, in the current study, the effect of infill density (IFD), printing speed (PTS), wall thickness (WLT), and layer thickness (LYT) has been investigated on the punch shear strength using Response Surface Methodology. The Analysis of Variance (ANOVA) has been performed for predicting statistical model with 95% confidence interval. During the statistical analysis, the terms with p-value lower than 0.05 were considered significant and the influence of process parameters has been examined using microscopic images. The surface plots have been used for discussing the effect of interactions between printing parameters. The statistical results revealed IFD as the most significant contributing factor, followed by PTS, LYT, and WLT. The study concluded by optimization of printing parameters for obtaining the highest punch shear strength.

Experimental investigation of ultrasonic assisted coating on three-point bending behavior of 3D printed polymeric bone plates for biomedical applications

3D printed Poly Lactic Acid (PLA) bone plates exhibit limited three-point bending strength, restricting their viability in biomedical applications. The application of polydopamine (PDM) enhances the three-point bending strength by undergoing covalent interactions with PLA molecular structure. However, the heavy nature of PDM particles leads to settling at the container base at higher coating solution concentrations. This study investigates the impact of ultrasonic-assisted coating parameters on the three-point bending strength. Utilizing Response Surface Methodology (RSM) for statistical modeling, the study examines the influence of ultrasonic vibration power (UP), coating solution concentration (CC), and submersion time (TIME). RSM optimization recommended 100 % UP, 6 mg/ml CC, and 150 min TIME, resulting in maximum three-point bending strength of 83.295 MPa. Microscopic images from the comparative analysis revealed non-uniform coating deposition with mean thickness of 6.153 µm under normal coating. In contrast, ultrasonic-assisted coating promoted uniform deposition with mean thickness of 18.05 µm. The results demonstrate that ultrasonic-assisted coating induces PDM particle collision, preventing settling at the container base, and enhances three-point bending strength by 7.27 % to 23.24 % compared to the normal coating condition. This study emphasizes on the potential of ultrasonic-assisted coating to overcome the limitations of direct immersion coating technique.

Investigation of transient machining in the cortical bone drilling process by conventional and axial vibration-assisted drilling methods

A temperature exceeding the safety threshold and excessive drilling force occurring during bone drilling may lead to irreversible damage to bone tissue and postoperative complications. Previous studies have shown that vibration-assisted drilling methods could have lower temperatures and drilling forces than those of the conventional drilling method; we hypothesized that the main reason for these reductions stems from the differences in the transient machining processes between conventional and vibration-assisted drilling methods. To investigate these differences, comparative experiments and two-dimensional finite element models were performed and developed. The differences in the transient machining processes were verified by experimentation and clearly exhibited by the finite element models. Compared with the steady cutting process that produced continuous-spiral chips in the conventional drilling method, transient machining in the low-frequency vibration-assisted drilling method was a periodically dynamic cutting-separation process that produced uniform petal chips with specific settings of drilling and vibration parameters. Moreover, the transient machining process in the ultrasonic vibration-assisted drilling method was transformed into a combined action with high-speed impact and negative rake angle cutting processes; this action produced a large proportion of powdery chips. Therefore, it could be concluded that the superposed axial vibration significantly changed the transient machining process and radically changed the mechanical state and thermal environment; these changes were the main reason for the apparent differences in the drilling performance levels.

Prediction of temperature elevation in rotary ultrasonic bone drilling using machine learning models: An in-vitro experimental study

Bone drilling is frequently used during orthopaedic surgeries to treat the fractured part of the bone. A major concern for surgeons is the increase in temperature during real-time orthopaedic bone drilling. The temperature elevation at the bone-tool interface may cause permanent death of regenerative soft tissues and cause thermal osteonecrosis. A robust predictive machine-learning model is suggested in this in-vitro research for monitoring temperature rise during surgery. The objective of the present work is to introduce different machine learning algorithms for predicting temperature elevations in rotary ultrasonic bone drilling. Different machine-learning models were compared with the standard response surface methodology. The performance and accuracy of different predictive models were compared at different error metrics. It was witnessed that support vector machines performed the best for predicting the change in temperature in comparison to other predictive models. Moreover, the error metrics for statistical response surface methodology analysis were comparatively higher than the machine learning algorithms. By using machine learning models, it is possible to predict temperature rise during bone drilling.

Computational analysis of cutting parameters based on gradient Voronoi model of cancellous bone

Bone cutting is a complicated surgical operation. It is very important to establish a kind of gradient porous bone model in vitro which is close to human bone for the research of bone cutting. Due to the existing bone cutting researches are based on solid bone model, which is quite different from human bone tissue structure. Therefore, Voronoi method was used to establish a gradient porous bone model similar to real bone tissue to simulate the process of bone drilling in this paper. High temperature and large cutting force during bone drilling can cause serious damage to bone tissue. Urgent research on bone drilling parameters is necessary to reduce cutting temperature and cutting force. The finite element analysis (FEA) of Voronoi bone models with different gradients is carried out, and a Voronoi model which is similar to real bone tissue is obtained and verified by combining the cutting experiment of pig bone. Then orthogonal experiments are designed to optimize the cutting parameters of Voronoi bone model. The range method is used to analyze the influence weights of cutting speed, feed speed and tip angle on cutting temperature and cutting force, and the least square method was used to predict the cutting temperature and cutting force, respectively. The gradient porous bone model constructed by Voronoi method was studied in detail in this paper. This study can provide theoretical guidance for clinical bone drilling surgery, and the prediction model of bone drilling has practical significance.

Thermal changes during drilling in human femur by rotary ultrasonic bone drilling machine: A histologic and ultrastructural study

Undue heat production in surgical bone drilling leads to osteonecrosis and can be an important cause of failure of osteosynthesis, impaired healing, and loosening of implants following orthopedic surgery. The present work aims to minimize heat production below the critical temperature for thermal osteonecrosis (i.e., 47°C) and obviate thermal bone damage due to drilling. A total of 20 samples from the shaft of the human femur were obtained at autopsies and drilling was performed at room temperature by an operation theater (OT) compatible rotary ultrasonic bone drilling (RUBD) machine. K-type thermocouples were used to measure the temperature rise during drilling and the physical changes of the bone samples were observed by infrared gama camera. Light microscopic and transmission electron microscopic studies were performed to evaluate the bone cell damage. The maximum temperature recorded in RUBD (40.6 ± 1.3°C) was much below the critical temperature for thermal osteonecrosis (p < .05) at the rotational speed of 2000 rpm. Light microscopic and ultrastructural studies also revealed that there was no appreciable damage to the bone cells. Conventional bone drilling (CD) on the other hand recorded much higher temperature (66.6 ± 3.2°C), tissue burn and bone cell necrosis. Hence, RUBD machine has a potentiality for its use in orthopedic surgery and may provide better results.

Effects of rotary ultrasonic bone drilling on cutting force and temperature in the human bones

Efficacy and outcomes of osteosynthesis depend on various factors including types of injury and repair, host factors, characteristics of implant materials and type of implantation. One of the most important host factors appears to be the extent of bone damage due to the mechanical force and thermal injury which are produced at cutting site during bone drilling. The temperature above the critical temperature (47 °C) produces thermal osteonecrosis in the bones. In the present work, experimental investigations were performed to determine the effect of drilling parameters (rotational speed, feed rate and drill diameter) and techniques (conventional surgical bone drilling and rotary ultrasonic bone drilling) on cutting force and temperature generated during bone drilling. The drilling experiments were performed by a newly developed bone drilling machine on different types of human bones (femur, tibia and fibula) having different biological structure and mechanical behaviour. The bone samples were procured from male cadavers with the age of second to fourth decades. The results revealed that there was a significant difference (p < 0.05) in cutting force and temperature rise for rotary ultrasonic bone drilling and conventional surgical bone drilling. The cutting force obtained in rotary ultrasonic bone drilling was 30%-40%, whereas temperature generated was 50%-55% lesser than conventional surgical bone drilling process for drilling in all types of bones. It was also found that the cutting force increased with increasing feed rate, drill diameter and decrease in rotational speed, whereas increasing rotational speed, drill diameter and feed rate resulted in higher heat generation during bone drilling. Both the techniques revealed that the axial cutting force and the temperature rise were significantly higher in femur and tibia compared with the fibula for all combinations of process parameters.

Comprehensive analysis on orthopedic drilling: A state-of-the-art review

Bone drilling is a well-known internal fixation procedure to drill a hole, fixing the bone fragments to reduce the susceptibility of permanent paralysis. The success of bone drilling is evaluated based on the extent of osteonecrosis in terms of heat generation, tissue damage, quality of hole, and drilling forces. The appropriate control of cutting conditions, drill geometric parameters, and bone-specific parameters offer bone drilling a viable solution through conventional and non-conventional drilling techniques. The majority of the published research work considers only limited parameters and tries to optimize the drilling parameters and performance measures. However, bone drilling involves numerous conventional and non-conventional drilling parameters and technologies. In order to develop a better understanding of all the studied parameters and performance measures, there is a dire need to develop a framework. The key objective of this review study is to establish a hierarchy of the framework by collecting almost all the parameters studied until now and addressed the relationship between parameters and performance measures to diminish the controversies in the published literature. Therefore, this framework is novel in nature, organizing all the parameters, performance measures, logical comparisons, and limitations of studies. This holistic review can help medical surgeons and design engineers to understand the complicated relationship among parameters and performance measures associated with this state-of-art technologies. Also, modeling, simulations, and optimization techniques are included to explore the application of such techniques in recent advancements in orthopedic drilling.

An in-vitro study of temperature rise during rotary ultrasonic bone drilling of human bone

Temperature rise in surgical bone drilling is an important factor that leads to death of the bone cells, known as Osteonecrosis, and results into poor osteosynthesis i.e. implant failure. The present work aims to study the temperature rise during bone drilling by a recently developed operation theatre (OT) compatible machine. The temperature during the drilling process was recorded from K-type thermocouple devices, which were embedded in the human tibial bone at four different positions (at 0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) from the drilling site. Comparative study revealed that rotary ultrasonic bone drilling (RUBD) technique produced lesser temperature (40 - 50%) than conventional drilling on human tibia. Statistical model was developed to predict the temperature rise in RUBD process using response surface methodology (RSM), and the optimum parameters were determined using Genetic Algorithm. Analysis of variance (ANOVA) was carried out at a confidence interval of 95 percent (α = 0.05) to determine the influence of various drilling parameters such as rotational speed, feed rate, drill diameter and abrasive particle size on temperature rise. It was observed that the rotational speed was responsible for the maximum temperature rise (51.8%) followed by drill diameter (18.8%), and abrasive particle size (14.3%); whereas, the feed rate contributed minimal (4%) temperature rise.

In vitro comparison of conventional surgical and rotary ultrasonic bone drilling techniques

In orthopedic and trauma surgical operations, drilling of bone is one of the commonly used procedures performed in hospitals and is a clinical practice for fixing the fractured parts of human bones. Force, torque and temperature play a significant role during the bone drilling and decide the stability of the medical implants. Therefore, it is necessary to minimize force, torque and temperature while drilling to avoid the thermal necrosis and osteosynthesis. This study focused on studying the influence of various types of bone drilling parameters (rotational speed, feed rate, drill diameter and ultrasonic amplitude), tools (solid tool, hollow tool and conventional twist drill bit) and techniques (conventional surgical drilling, rotary ultrasonic bone drilling and rotary bone drilling) on force, torque, temperature and microcracks produced in the drilled surface of the bone. The experimental investigations were conducted on porcine bone samples to perform the comparative study. Results revealed that increasing the diameter of drill tool and feed rate results in the increase in force, torque and temperature, while low rotational speed (500 r/min) generated a low temperature, high cutting force and torque for all types of drilling processes and tools evaluated in this study. Experimental results also revealed that rotary ultrasonic bone drilling with hollow tool generated the lowest cutting force, torque, temperature (<47 °C) and microcracks in the drilled surface of the bone as compared to the other four types of drilling techniques evaluated in this study. Influence of external irrigation technique on temperature was also studied with respect to the rotary ultrasonic bone drilling with a hollow tool, which could eliminate the problem of thermal necrosis. In conclusion, this study revealed that the rotary ultrasonic bone drilling process with hollow tool produced lesser cutting force as compared to rotary bone drilling and conventional surgical drilling for hollow and solid tools. The study also revealed that rotary ultrasonic bone drilling process has the potential to minimize the cutting force, torque and temperature as compared to the conventional surgical drilling for orthopedic surgery.

Measurement and prediction of drilling force in fresh human cadaver mandibles: A pilot study

BACKGROUND

Bone drilling is a vital procedure in implant surgery and dental implant training systems based on virtual reality technology.

PURPOSE

Predict and update drilling force in real time based on a virtual dental implant training system and lay the foundation for realizing force feedback in dental implant training instruments.

MATERIALS AND METHODS

An experimental platform was established to measure the drilling force for human mandibles from donors of different ages. Response surface methodology was applied to analyze the drilling force.

RESULTS

Force regression equations for different age groups were acquired. The order of the effects (from greatest to least) of the drilling parameters on the drilling force was the drill bit diameter, feed rate, and rotational speed. To obtain the minimum force, higher rotational speeds, lower feed rates, and smaller diameters were preferred within the range of commonly used medical reference parameters of bone drilling.

CONCLUSION

The experimental data were confirmed to be scientific for the predicted models of drilling force.

Experimental investigations and statistical modeling of cutting force and torque in rotary ultrasonic bone drilling of human cadaver bone

Cutting force and torque are important factors in the success of the bone drilling process. In the recent past, many attempts have been made to reduce the cutting force and torque in the bone drilling process. In this work, drilling on human cadaver bones has been performed using rotary ultrasonic bone drilling process to investigate the effect of drilling parameters on cutting force and torque. The experimental work was carried on a recently developed rotary ultrasonic bone drilling machine for surgical operations. The experimental work was performed in two phases. The first phase includes a comparative study between rotary ultrasonic bone drilling and conventional surgical bone drilling, to study the influence of various drilling parameters (rotational speed, drill diameter, and drilling tool feed rate) on the cutting force and torque. The results revealed that the cutting force and torque produced during drilling operations in rotary ultrasonic bone drilling were lesser (30%–40%) than conventional surgical bone drilling. In the second phase, response surface methodology was used to perform the statistical modeling of cutting force and torque in rotary ultrasonic bone drilling process. Analysis of variance was performed at a confidence interval of 95% to analyze the significant contribution ( p < 0.05) of process parameters (drilling speed, feed rate, drill diameter, and abrasive particle size) on the responses (cutting force and torque). The confirmatory experiments were performed to validate the developed statistical models. It was found that both cutting force and torque decrease with increase in drilling speed and increases with the increasing drill diameter, feed rate, and abrasive particle size.

Experimental investigation of the temperature elevation in bone drilling using conventional and vibration-assisted methods

Bone drilling is widely used in orthopaedics for inserting screws and fixing prostheses. Thermal necrosis is one of the major problems that may seriously affect post-operative recovery. Accordingly, this paper mainly focuses on comparing the influences of conventional drilling (CD), ultrasonic vibration-assisted drilling (UVAD) and low-frequency vibration-assisted drilling (LFVAD) methods, and drilling parameters on the temperature elevation in bone drilling process. A full factorial experiment was performed, and the temperatures were measured using an infrared camera. The lowest temperature elevation was obtained by LFVAD compared with CD and UVAD at the same drilling conditions. Setting CD as a reference, the maximum difference between LFVAD and CD was approximately -4 °C, whereas that between UVAD and CD was approximately 16 °C. The temperature elevation increases linearly with the spindle speed and follows an inverted U-shaped curve, with the feed rate having a peak at 40 min/mm in each drilling method. The results were discussed with regard to the features of LFVAD and UVAD. It was expected that the LFVAD could achieve minimal thermal damage and attain better results in the medical bone drilling process.

Optimization of drilling parameters for thermal bone necrosis prevention

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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

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.

CONCLUSIONS

It is envisaged that finite element simulation with RSM can simplify tedious experimental works and useful in the clinical application to avoid bone necrosis.

Rotary ultrasonic drilling on bone: A novel technique to put an end to thermal injury to bone

Bone drilling is common in orthopedic procedures and the heat produced during conventional experimental drilling often exceeds critical temperature of 47 °C and induces thermal osteonecrosis. The osteonecrosis may be the reason for impaired healing, early loosening and implant failure. This study was undertaken to control the temperature rise by interrupted cutting and reduced friction effects at the interface of drill tool and the bone surface. In this work, rotary ultrasonic drilling technique with diamond abrasive particles coated on the hollow drill tool without any internal or external cooling assistance was used. Experiments were performed at room temperature on the mid-diaphysis sections of fresh pig bones, which were harvested immediately after sacrifice of the animal. Both rotary ultrasonic drilling on bone and conventional surgical drilling on bone were performed in a five set of experiments on each process using identical constant process parameters. The maximum temperature of each trial was recorded by K-type thermocouple device. Ethylenediaminetetraacetic acid decalcification was done for microscopic examination of bone. In this comparative procedure, rotary ultrasonic drilling on bone produced much lower temperature, that is, 40.2 °C ± 0.4 °C and 40.3 °C ± 0.2 °C as compared to that of conventional surgical drilling on bone, that is, 74.9 °C ± 0.8 °C and 74.9 °C ± 0.6 °C with respect to thermocouples fixed at first and second position, respectively. The conventional surgical drilling on bone specimens revealed gross tissue burn, microscopic evidence of thermal osteonecrosis and tissue injury in the form of cracks due to the generated force during drilling. But our novel technique showed no such features. Rotary ultrasonic drilling on bone technique is robust and superior to other methods for drilling as it induces no thermal osteonecrosis and does not damage the bone by generating undue forces during drilling.

In-situ tool wear monitoring and its effects on the performance of porcine cortical bone drilling: a comparative in-vitro investigation

Background

Drilling is one of the most widely used process in orthopaedic surgical operation and the same drill bit is used a number of times in hospitals. Using the same drill bit a several times may be the cause of osteosynthesis and osteonecrosis.

Methods

In the present work, the effect of repeated orthopaedic surgical twist drill bit on the tool wear, force, torque, temperature and chip morphology during porcine cortical bone drilling is studied. Results were compared with rotary ultrasonic drilling (RUD) on the same bone using a hollow drill tool coated with diamond grains. A sequence of 200 experiments (100 with each process, RUD and CD) were performed with constant process parameters.

Results

Wear area on the drill bit is significantly increased as the drill bit is used repeatedly in CD, whereas no attritious wear was found on the diamond coated grains in RUD.

Conclusions

Comparative results showed that cutting force, torque and temperature increased as a function of tool wear in CD as the same drill bit was used a number of times. No significant variation in the cutting force and torque was observed in RUD as the number of drilled holes increased.