An in vitro study of bone drilling: infrared thermography and evaluation of thermal changes of bone and drill bit

Comparison of the thermal bone damage done by the oscillating saw and bone mill burr during total knee arthroplasty

Background

Thermal osteonecrosis from bone cutting during total knee arthroplasty (TKA) may cause aseptic implant loosening. The study compares thermal bone injury from oscillating saw (CTKA) and bone milling burr treatments (RATKA).

Method

A prospective study comparing thermal necrosis during CTKA and RATKA was performed. The sample size (n = 36) was determined with 18 patients per group, assuming a 15 % relative increase in thermal necrosis with RATKA, with statistical thresholds set at α = 5 % and β = 10 %. The upper tibia cut surface was analyzed, with histological sections examined from 20 randomly selected fields. Thermal necrosis was evaluated by determining the proportion of non-viable cells relative to viable ones and measuring the depth from the cut bone surface at which the first intact osteocyte was observed. Statistical analysis was conducted using appropriate comparative tests, including Chi-square and t-tests, with significance determined at a threshold of p < 0.05.

Results

There was no significant variability in preoperative patient characteristics (gender, age, body mass index, diagnosis, range of motion, deformity and comorbidities) between CTKA (n = 18) and RATKA (n = 18) groups. The percentage of dead osteocytes at the resected surface in CTKA and RATKA were 40.3 % and 46.5 % respectively (p = 0.6309). The minimum depth where viable osteocytes were found was 25.5 ± 3.5 μmm and 27.1 ± 3.6 μmm in CTKA and RATKA respectively (p value = 0.091).

Conclusion

Conventional TKA and RATKA produce similar thermal effects on bone, with no significant difference in osteocyte viability. This indicates that both surgical methods are comparable regarding thermal impact on bone health.

Thermographic analysis of perforations in polyurethane blocks performed with experimental conical drill bit in comparison to conventional orthopedic drill bit: a preliminary study

OBJECTIVE

Conical orthopedic drill bits may have the potential to improve the stabilization of orthopedic screws. During perforations, heat energy is released, and elevated temperatures could be related to thermal osteonecrosis. This study was designed to evaluate the thermal behavior of an experimental conical drill bit, when compared to the conventional cylindrical drill, using polyurethane blocks perforations.

RESULTS

The sample was divided into two groups, according to the method of drilling, including 25 polyurethane blocks in each: In Group 1, perforations were performed with a conventional orthopedic cylindrical drill; while in Group 2, an experimental conical drill was used. No statistically significant difference was observed in relation to the maximum temperature (MT) during the entire drilling in the groups, however the perforation time (PT) was slightly longer in Group 2. Each drill bit perforated five times and number of perforations was not correlated with a temperature increase, when evaluated universally or isolated by groups. The PT had no correlation with an increase in temperature when evaluating the perforations universally (n = 50) and in Group 1 alone; however, Group 2 showed an inversely proportional correlation for these variables, indicating that, for the conical drill bit, drillings with longer PT had lower MT.

Limiting Temperature Rise in Cochlear Implantation Bone Drilling: A Novel Approach

OBJECTIVE

In the process of cochlear implantation surgery, it is crucial to develop a method to control the temperature during the drilling of the implant channel since high temperatures can result in damage to bone and nerve tissue.

METHODS

This paper simplified the traditional point heat source temperature rise model and proposed a novel extreme peck drilling model to quantitatively calculate the maximum temperature rise value. It is also innovatively introduced a new method for calculating the best peck drilling duty cycle to strictly control the maximum temperature rise value. Besides, the neural network is trained with virtual data to identify two important thermal parameters in the temperature rise model.

RESULTS

In the experiment of epoxy resin and temporal bone, the difference between predicted maximum temperature and actual maximum temperature was less than 1.5 °C, and the error rate was less than 10%. And the error source was analyzed by variational mode decomposition, along with discussion of potential solutions. In the temperature control experiment, the model successfully controlled the maximum temperature rise within 10 °C.For cochlear implantation surgery, we also divide the implantation channel into different stages based on the bone density in CT images to identify thermal parameters and calculate drilling strategies.

CONCLUSION

This method provides a new strategy for accurate and effective control of borehole heat generation.

SIGNIFICANCE

These achievements provide new ideas and directions for research in cochlear implantation surgery and related fields, and are expected to have extensive application in medical practice.

Effect of process parameters on the temperature changes during robotic bone drilling

In medical surgery, bone drilling is an inevitable procedure. The thermal necrosis in the drilling process can affect post-operative recovery. In this study, the method of drill bit precooling is proposed in bone drilling with robot assisted system. The influence of process parameters on the drilling temperature were investigated and analyzed. The results showed that the method of drill bit precooling could reduce the drilling temperature. The drill bit starting temperature and the feed rate were more important parameters on the drilling temperature compared with rotational speed and cooling length of the drill bit. The quadratic regression model obtained from response surface experiments can predicted the drilling temperature correctly under the range of process parameters in this study. The optimal parameter combination is rotational speed = 1610 rpm, feed rate = 0.5 mm/s, the starting temperature of drill bit = 8°C, and the cooling length = 34.8 mm. The results provide an effective method to reduce thermal necrosis of bone cells in drilling.

Resection of bone by sagittal saw: Investigation of effects of blade speed, feed rate, and irrigation on temperature rise

Heat generation during bone cutting by sagittal saw may lead to temperature rise and possible incidence of thermal necrosis. The aim of the present research is to examine the effect of saw blade oscillation rate, blade feed rate, and irrigation by physiological saline solution on the bone temperature rise during sawing in order to determine the desired conditions for reducing the extent of thermal damage. For this purpose, empirical tests of bovine femur cutting were performed in 15 states, including five levels for the blade oscillation rate (10,000-18,000 cpm with 2000 cpm intervals) and three levels for the feed rate (10-30 mm.min^-1 with 10 mm.min^-1 intervals) for dry conditions; and five states, including five levels for the blade oscillation rate (10,000-18,000 cpm with 2000 cpm intervals) and one level in feed rate of 20 mm.min^-1 for the irrigation conditions. The results indicated that the bone temperature rise had a direct relationship with the blade oscillation rate and an inverse relationship with its feed rate. In the state of no cooling, the minimum temperature rise (ΔT = 65.45°C) occurred at the blade speed of 10,000 cpm and feed rate of 30 mm.min^-1, while in the state of sawing with irrigation, the temperature rise almost did not exceed the allowable range (ΔT ≤ 10°C). The results suggested that to lower the possibility of incidence of osteonecrosis in the bone resection by sagittal saw, cooling with physiological saline solution or application of the minimum blade oscillation rate and maximum feed rate is recommended.

A predictive model for cortical bone temperature distribution during drilling

Bone drilling is an important procedure in medical orthopedic surgery and it is inevitable that heat will be generated during the drilling process and higher temperatures can cause thermal damage to the bone tissue near the drilled hole. Therefore, the capability to obtain the cortical bone drilling temperature distribution area can have great significance for medical bone surgery. Based on the theory of heat transfer, a predictive model for cortical bone drilling temperature distribution was established. The energy distribution coefficient in cortical bone drilling was derived, based on conjugate gradient inversion. A cortical bone drilling experiment platform was built to verify the temperature distribution prediction model. The results show that the model of cortical bone drill temperature distribution could predict accurately the drilling temperature distribution, both for different depths and for different radial distances. Additionally, the effects of different drilling conditions (spindle speed, feed rate, drill diameter) on the temperature of drilling cortical bone were considered.