Introduction and Objective. Digital infra-red thermography may have the capability of identifying local inflammations. Nevertheless, the role of thermography in diagnosing pin site infection has not been explored yet and the reliability and validity of this method for pin site surveillance is in question. The purpose of this study was to explore the capability and intra-rater reliability of thermography in detecting pin site infection. Materials and Methods. This explorative proof of concept study follows GRRAS -guidelines for reporting reliability and agreement studies. After clinical assessment of pin sites by one examiner using Modified Gordon Pin Infection Classification (Grade 0 – 6), thermographic images of the pin sites were captured with a FLIR C3 camera and analyzed by the FLIR tools software package. The maximum skin temperature around the pin site and the maximum temperature for the whole thermographic picture was measured. Intra-rater agreement was established and test-retests were performed with different camera angles. Results. Thirteen (4 females) patients (age 9–72 years) were included. Indications for frames: 4 fracture, 2 deformity correction, 1 lengthening, 6 bone transport. Days from surgery to thermography ranged from 27 to 385 days. Overall, 231 pin sites were included. Eleven pin sites were diagnosed with early signs of infection: five grade 1, five grade 2, one grade 3. Mean pin site temperature was 33.9 °C (29.0–35.4). With 34 °C as cut-off value for infection, sensitivity was 73%, specificity 67%, positive predictive value 10% and negative predictive value 98%. Intra-rater reliability for thermography was ICC 0.85 (0.77–0.92). The temperature measured was influenced by the camera postioning in relation to pin site with a variance of 0.2. Conclusions. Measurements of pin sites using the handheld FLIR C3 infrared camera was a reliable method and the temperature was related to infection grading. This study demonstrates that digital thermography with a handheld camera might be used for monitoring the pin sites after operations to detect early infection, however, future larger prospective studies are necessary

Thermal osteonecrosis is a side effect when used Kirschner (K) wires and drills in orthopaedic surgeries. This osteonecrosis may endanger the fixation. Orthopaedic surgeons sometimes have to use unsharpened K-wires in emergent surgery. The thermal effect of used and unsharpened K wire is ambiguous to the bone. This experimental study aims to assess the thermal osteonecrosis while drilling bone with three different types of K-wires especially a previously used unsharpened wire and its thermographic measurements correlation. Two different speeds of rotation were chosen to investigate the effect of speed on thermal necrosis to the bone.

A total of 16 New Zealand white rabbits weighing a mean of 2.90 kg (2.70 – 3.30 kg) were used. All rabbits were operated under general anaesthesia in a sterile operating room. Firstly, 4 cm longitudinal lateral approach was used to the right femur and then the femur was drilled with 1.0 mm trochar tip, spade tip and previously used unsharpened K-wires and 1.0 mm drill bit at 1450 rpm speed. Left femur was drilled with same three type K-wires and drill bit at 330 rpm speed. One cm distance was left among four penetrations on the femur. The thermal changes were recorded by Flir® E6 Thermal Camera from 50 cm distance and 30-degree angle. Thermographic measurements saved for every drilling process and recorded for the highest temperature (°C) during the drilling. All subjects were sacrificed post-operatively on the eighth day and specimens were prepared for the histological examination. The results of osteonecrosis assessment score and thermographic correlation were evaluated statistically.

Histological specimens were evaluated by the scoring of osteonecrosis, osteoblastic activity, haemorrhage, microfracture and inflammation. Results were graded semi-quantitatively as none, moderate or severe for osteonecrosis, haemorrhage and inflammation. The microfracture and osteoblastic activity were evaluated as present or absent. There was no meaningful correlation between osteonecrosis and the drilling speed (p=0.108). There was less microfracture zone which was drilled with trochar tip K-wires at 1450 rpm speed (p=0.017). And the drilling temperature of trochar tip K-wires was higher than the others(p=0.001). Despite this evaluation, osteonecrosis zone of spade and unsharpened tip K-wires were more than trochar tip K-wires (p=0.039). The drill bit at 330 rpm caused the least osteonecrosis and haemorrhage and respectfully the lowest drilling temperature (p=0,001). The osteoblastic activity shows no difference between the groups. (p=0,122; 0,636;0.289)

On the contrary to the literature, our experiment showed that there is no meaningful correlation between osteonecrosis score and temperature produced by drilling. The histological assessment showed the osteonecrosis during short drilling time but, not clarify the relation with drilling temperature. Eventually, the osteonecrosis showed a positive correlation with drilling time independently of drilling temperature at 330 rpm. (p=0,042) These results show that we need more studies to understand about osteonecrosis and its relationship with drilling heat temperature. Trochar tip K-wires creates higher drilling temperature but less osteonecrosis than a spade and unsharpened cut tip K-wires. Using unsharpened tip K-wire causes more osteonecrosis. Previously used and, unsharpened K-wires should be discarded

To detect early signs of infection infrared thermography has been suggested to provide quantitative information. Our vision is to invent a pin site infection thermographic surveillance tool for patients at home. A preliminary step to this goal is the aim of this study, to automate the process of locating the pin and detecting the pin sites in thermal images efficiently, exactly, and reliably for extracting pin site temperatures. A total of 1708 pin sites was investigated with Thermography and augmented by 9 different methods in to totally 10.409 images. The dataset was divided into a training set (n=8325), a validation set (n=1040), and a test set (n=1044) of images. The Pin Detection Model (PDM) was developed as follows: A You Only Look Once (YOLOv5) based object detection model with a Complete Detection Intersection over Union (CDIoU), it was pre-trained and finetuned by the through transfer learning. The basic performance of the YOLOv5 with CDIoU model was compared with other conventional models (FCOS and YOLOv4) for deep and transition learning to improve performance and precision. Maximum Temperature Extraction (MTE) Based on Region of Interest (ROI) for all pin sites was generated by the model. Inference of MTE using PDM with infected and un-infected datasets was investigated. An automatic tool that can identify and annotate pin sites on conventional images using bounding boxes was established. The bounding box was transferred to the infrared image. The PMD algorithm was built on YOLOv5 with CDIoU and has a precision of 0.976. The model offers the pin site detection in 1.8 milliseconds. The thermal data from ROI at the pin site was automatically extracted. These results enable automatic pin site annotation on thermography. The model tracks the correlation between temperature and infection from the detected pin sites and demonstrates it is a promising tool for automatic pin site detection and maximum temperature extraction for further infection studies. Our work for automatic pin site annotation on thermography paves the way for future research on infection assessment using thermography

Introduction. Patients with external fixators are at risk of pin site infection. A more objective assessment of possible pin site infection is warranted, particularly for future home-based monitoring of pin sites. The aim was to determine if thermography can detect signs of inflammation around pin sites by 1) Establishing a maximum temperature cut-off value 2) Investigating the correlation between local temperature and visual signs of inflammation 3) Adjust for anatomical location and ambient room temperature. Method. This was a cross-sectional international multi-center study following STROBE guidelines. All patients with external ring-fixators scheduled for a visit in the out-patient clinic were eligible. Visual signs of inflammation were categorized using the Modified Gordon classification System (MGS, simplified sMGS). Thermographic imaging was done with an infrared camera (FLIR T540) and the maximum temperature within the ROI (MaxTp) was the primary outcome measure. Sample size and reliability were estimated. Cohen-Kappa, ROC-curve/AUC and Poisson regression were used for statistical analysis. Result. Data from 1970 pin sites were included. Inter-rater reliability of MGS was Kappa=0.79 and for MaxTp ICC=0.99 (95%CI: 0.99;0.99). Overall, a tendency of rising temperature with increasing sMGS was seen. The difference between sMGS=0 and sMGS>0 was significant. The performance of MaxTp as a screening tool to detect inflammation was reasonable with an AUC of 0.71 (95% CI: 0.65-0.76). The empirically optimal cut-off value was 34.1°C (Sensitivity=65%, Specificity=72%, Positive predictive value=23%, Negative Predictive value=94%). A 1°C increase in MaxTp increased the RR of visual signs of inflammation by a factor 1.5 (95% CI: 1.3; 1.7). Conclusion. We found a clinical positive association between the temperature at the pin site measured with thermography and visual signs of inflammation. The empirically optimal temperature cut-off value for inflammation screening was 34.1°C. Thermography may be a promising tool for a for a future point of care technology

We undertook a study of the anti-tumour effects of hyperthermia, delivered via magnetite cationic liposomes (MCLs), on local tumours and lung metastases in a mouse model of osteosarcoma. MCLs were injected into subcutaneous osteosarcomas (LM8) and subjected to an alternating magnetic field which induced a heating effect in MCLs. A control group of mice with tumours received MCLs but were not exposed to an AMF. A further group of mice with tumours were exposed to an AMF but had not been treated with MCLs. The distribution of MCLs and local and lung metastases was evaluated histologically. The weight and volume of local tumours and the number of lung metastases were determined. Expression of heat shock protein 70 was evaluated immunohistologically. Hyperthermia using MCLs effectively heated the targeted tumour to 45°C. The mean weight of the local tumour was significantly suppressed in the hyperthermia group (p = 0.013). The mice subjected to hyperthermia had significantly fewer lung metastases than the control mice (p = 0.005). Heat shock protein 70 was expressed in tumours treated with hyperthermia, but was not found in those tumours not exposed to hyperthermia.

The results demonstrate a significant effect of hyperthermia on local tumours and reduces their potential to metastasise to the lung.