Infrared Thermography in Wound Care, Surgery, and Sports Medicine: A Review

Application of infrared thermography for predicting pressure injury healing: A prospective study

BACKGROUND

An accurate assessment of pressure injury healing is crucial for the timely implementation of nursing intervention. This study aimed to investigate the accuracy of infrared thermography-based wound temperature measurement in predicting wound outcomes.

METHODS

This prospective, 16 days observational study included 156 adults with pressure injury. The temperature of wound bed, periwound skin and normal skin was recorded by using infrared thermography every three days. After that, three relative temperatures of PI were analyzed. The aim was to assess the significance of wound temperature in predicting healing outcomes for pressure injuries.

RESULTS

Relative temperature between periwound skin and normal skin was positively correlated with pressure injury healing (r > 0.64). Particularly the first day of follow up, it was found to be closely related to pressure injury healing (r = 0.687). On the last day and median time (the eighth to ninth day) of follow up, the optimal cutoff values of the indicator were negative values (periwound skin temperature was lower than normal skin). COX proportional hazard regression model analysis showed that relative temperature between periwound skin and normal skin on the first day of follow-up was the most significant predictor of pressure injury healing, and the healing risk increased largest- 8.79 times (95%CI: 4.53, 17.05), when its temperature greater than 0.000 °C.

CONCLUSION

Relative temperature between periwound skin and normal skin monitoring by infrared thermography better than visual assessment which can objectively serve as an indicator for predicting the healing status of pressure injury.

Symptoms and joint degeneration correlate with the temperature of osteoarthritic knees: an infrared thermography analysis

PURPOSE

This study aim was to analyze the joint temperature of patients affected by bilateral knee osteoarthritis (OA) using infrared thermography to investigate whether thermographic imaging patterns are influenced by the severity of symptoms and joint degeneration.

METHODS

Sixty-sixpatients ranging from 43 to 78 years old (63.3 ± 8.8 years) with bilateral knee OA and one symptomatic knee were enrolled. Thermograms of the two knees were captured using a thermographic camera FLIR T1020 and analyzed with the ResearchIR software to calculate the temperature of the overall knee and the four regions of interest (ROIs): patella, suprapatellar, medial, and lateral areas.

RESULTS

The temperature of knees affected by OA was influenced by joint degeneration level and symptoms: patients with higher OA grade in the symptomatic knees presented higher total knee temperatures compared to the asymptomatic ones (p = 0.002), as well as in the patellar (p = 0.005), lateral (p = 0.002), and medial (p = 0.001) areas. On the other hand, patients with the same OA level in the two knees presented a higher temperature in the symptomatic knee only in the medial area (p = 0.037). Symptomatic knees demonstrated a different pattern compared to asymptomatic knees, with the medial area presenting the highest temperature changes (p = 0.020). Patients reporting prevalent pain in the lateral knee area presented higher differences in total knee temperature (0.7 ± 0.7 °C) than patients with pain in the medial area (0.1 ± 0.5 °C) (p = 0.023).

CONCLUSION

The temperature of knees affected by OA is influenced by the degree of joint degeneration and by the presence of symptoms, with higher temperatures found in symptomatic joints, especially with prevalent lateral knee pain, and in more severe OA. Symptomatic knees demonstrated a different pattern compared to asymptomatic knees, with the medial area presenting the highest temperature changes.

Flexible bioelectronic systems with large-scale temperature sensor arrays for monitoring and treatments of localized wound inflammation

Continuous monitoring and closed-loop therapy of soft wound tissues is of particular interest in biomedical research and clinical practices. An important focus is on the development of implantable bioelectronics that can measure time-dependent temperature distribution related to localized inflammation over large areas of wound and offer in situ treatment. Existing approaches such as thermometers/thermocouples provide limited spatial resolution, inapplicable to a wearable/implantable format. Here, we report a conformal, scalable device package that integrates a flexible amorphous silicon-based temperature sensor array and drug-loaded hydrogel for the healing process. This system can enable the spatial temperature mapping at submillimeter resolution and high sensitivity of 0.1 °C, for dynamically localizing the inflammation regions associated with temperature change, automatically followed with heat-triggered drug delivery from hydrogel triggered by wearable infrared light-emitting-diodes. We establish the operational principles experimentally and computationally and evaluate system functionalities with a wide range of targets including live animal models and human subjects. As an example of medical utility, this system can yield closed-loop monitoring/treatments by tracking of temperature distribution over wound areas of live rats, in designs that can be integrated with automated wireless control. These findings create broad utilities of these platforms for clinical diagnosis and advanced therapy for wound healthcare.

Digital infrared thermography and machine learning for diabetic foot assessment: thermal patterns and classification

Objectives

Digital infrared thermography is a noninvasive tool used for assessing diseases, including the diabetic foot. This study aims to analyze thermal patterns of the foot sole in patients with type 2 diabetes mellitus using thermography and explore correlations with clinical variables. Additionally, a machine learning approach was developed for classification.

Methods

A total of 23 diabetic patients and 27 age- and sex-matched controls were included. Thermograms of the plantar foot surface were acquired and segmented into regions of interest. Mean foot temperature and temperature change index were calculated from predefined regions of interest. Pearson's correlation analysis was conducted for temperature measures, glycated hemoglobin, and body mass index. A two-layered cross-validation model using principal component analysis and support vector machines were employed for classification.

Results

Significant positive correlations were found between mean foot temperature and glycated hemoglobin (ρ = 0.44, p = 0.0015), as well as between mean foot temperature and body mass index (ρ = 0.35, p = 0.013). Temperature change index did not show significant correlations with clinical variables. The machine learning model achieved high overall accuracy (90%) and specificity (100%) with a moderate sensitivity (78.3%) for classifying diabetic and control groups based on thermal data.

Conclusions

Thermography combined with machine learning shows potential for assessing diabetic foot complications. Correlations between mean foot temperature and clinical variables suggest foot temperature changes as potential indicators. The machine learning model demonstrates promising accuracy for classification, suitable for screening purposes. Further research is needed to understand underlying mechanisms and establish clinical utility in diagnosing and managing diabetic foot complications.

Clinical Applications, Legal Considerations and Implementation Challenges of Smartphone-Based Thermography: A Scoping Review

Medical thermography is a non-invasive technique that allows the measurement of the temperature of the human body surface, exploiting the heat emitted by the body through the skin in the form of infrared electromagnetic radiation. Recently, smartphone-based thermography (ST) has drawn considerable attention. This scoping review (SR) aims to describe its current applications and reliability based on currently available research findings, also taking into account the medico-legal implications linked to its use. A search of the sources was conducted on multiple databases (PubMed, Scopus, Cochrane, Lilacs, Google Scholar). Based on a set of eligibility criteria, all articles deemed useful were included in the SR. Collected data, processed with descriptive statistics, are then discussed. From the initial 241 results, after duplicate removal and full-text reading based on inclusion/exclusion criteria, 20 articles were classified according to the main characteristics and indications and outcomes are highlighted based on clinical evidence. The most frequently documented fields of ST are wound care management and vascular surgery. Other disciplines are less explored (dentistry, ophthalmology, otorhinolaryngology, orthopedics, etc.). Practicality, operational simplicity and affordability of mobile thermographic devices are the chief strengths of this technology. Comparative studies with traditional thermal imaging methods are poor in terms of the number of patients analyzed but this technology showed high sensitivity and accuracy in the large number of patients enrolled in observational studies, encouraging the development of further operational protocols in all medical specialties. Gaining a deeper understanding of such techniques will also help settle the medico-legal issues which may arise from the clinical implementation of ST, thus appraising its reliability and safety from that perspective as well.

A pilot prospective study of forward-looking infrared (FLIR) camera measurements to predict postoperative wound complications in high-energy lower extremity fractures

PURPOSE

To prospectively determine if forward-looking infrared (FLIR) camera temperature measurements can predict postoperative wound complications in high-energy lower extremity fractures.

METHODS

This is a prospective cohort study from a single level 1 trauma centre. Adult patients who sustained unilateral high-energy lower extremity fractures (tibial plateau, tibial plafond, trimalleolar ankle, midfoot, or calcaneus fractures) were included in the study. Preoperative and post-induction FLIR thermographic measurements were taken using the FLIRONE ® PRO camera system. The main outcome of interest was the development of any wound related postoperative complication.

RESULTS

Forty-eight patients were included in the study. A majority of the patients were male (58%) with a mean age of 44.2 years. FLIR imaging detected temperature differences between the operative extremity and the contralateral extremity, both in the preoperative area and following induction (Pre-op: 33.0 vs 30.8, p < 0.001; Post-induction: 29.6 vs 28.5, p = 0.046). Overall, 11 (23.9%) patients experienced a wound complication. Regression analysis did not demonstrate a significant association between preoperative or post-induction FLIR measurements and the development of wound complications.

CONCLUSION

While FLIR imaging could detect temperature changes related to traumatic injury, these differences did not correlate with postoperative outcomes. Further large-scale study may be warranted.

LEVEL OF EVIDENCE

III.

The role of thermography in assessment of wounds. A scoping review

Assessment of wounds based on visual appearance has poor inter- and intra-rater reliability and it is difficult to differentiate between inflammation and infection. Thermography is a user-friendly quantitative image technique that collects the skin surface temperature pattern of the wound area and immediately visualizes the temperatures as a rainbow coloured diagram. The aim of this scoping review is to map and summarize the existing evidence on how thermography has been used to assess signs of inflammation in humans and animals with surgical or traumatic wounds. The method follows the Joanna Briggs Institute methodology. The databases searched were PubMed, Embase, CINAHL and Cochrane Library. 3798 sources were identified, 2666 were screened on title and abstract, 99 on full text and 19 studies were included for review. We found that the literature is diverse and originates from a variety of scientific fields. Thermography has been used to detect and predict inflammation and infection in surgical wounds. Grading systems based on the visual appearance correlate to temperature patterns detected with thermography. The general tendency is that thermography detects the temperature in a wound with inflammation to be warmer than a reference area or the same skin area before surgery. In a surgical wound the temperature is elevated 1-2 weeks after surgery due to natural physiological inflammation that induces healing, after 2 weeks the temperature of the wound area slowly and steady decreases to baseline over 1-3 months. If a secondary temperature peak happens during the healing phase of a surgical wound, it is likely that infection has occurred. Modern handheld thermographic cameras might be a promising tool for the clinician to quickly quantify the temperature pattern of surgical wounds to distinguish between inflammation and infection. However, firm evidence supporting infection thermography surveillance of surgical wounds as a technique is missing.

Non-invasive techniques for wound assessment: A comprehensive review

Efficient wound assessment is essential for healthcare teams to facilitate prompt diagnosis, optimize treatment plans, reduce workload, and enhance patients' quality of life. In recent years, non-invasive techniques for aiding wound assessment, such as digital photography, 3D modelling, optical imaging, fluorescence and thermography, as well as artificial intelligence, have been gradually developed. This paper aims to review the various methods of measurement and diagnosis based on non-invasive wound imaging, and to summarize their application in wound monitoring and assessment. The goal is to provide a foundation and reference for future research on wound assessment.

The Thermal Signature of Wound Healing

BACKGROUND

Despite major efforts in prevention, surgical site infections (SSIs) remain a burden on patients and the healthcare system and are associated with significant morbidity. SSIs are one of the costliest healthcare-associated infections. The diagnosis of SSIs is based mainly on clinical assessment, which may result in a delay in detection. The ability to detect SSIs in subclinical phase and initiate effective therapy earlier may reduce morbidity and hospital stay. In this study, we attempted to utilize long-wave infrared (LWIR) imaging to define the healing process of the surgical site and to detect abnormal healing.

METHODS

In this prospective study, 50 patients undergoing elective abdominal surgery had LWIR images of their incision obtained at determined intervals from their operation to discharge. Images were processed with proprietary algorithms to create a thermal topograph used to define the healing process.

RESULTS

Images of 45 patients were available for a final review. Of these 45 patients, 10 patients developed SSIs. Using the thermal topograph, 10 criteria for image analysis were defined, yielding a prediction of six out of the 10 SSIs and 35 out of the 35 normal healing wounds. Sensitivity was 60%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 90.1%, with 92% accuracy. A preliminary program was created that allows trained users to methodically evaluate images providing them with a risk estimate.

CONCLUSIONS

In this preliminary study, LWIR analysis of surgical wounds was able to identify normal and abnormal wound healing. Further large-scale studies are needed to validate results.

Stimuli-responsive drug delivery systems for inflammatory skin conditions

Inflammatory skin conditions highly influence the quality of life of the patients suffering from these disorders. Symptoms include red, itchy and painful skin lesions, which are visible to the rest of the world, causing stigmatization and a significantly lower mental health of the patients. Treatment options are often unsatisfactory, as they suffer from either low patient adherence or the risk of severe side effects. Considering this, there is a need for new treatments, and notably of new ways of delivering the drugs. Stimuli-responsive drug delivery systems are able to deliver their drug cargo in response to a given stimulus and are, thus, promising for the treatment of inflammatory skin conditions. For example, the use of external stimuli such as ultraviolet light, near infrared radiation, or alteration of magnetic field enables drug release to be precisely controlled in space and time. On the other hand, internal stimuli induced by the pathological condition, including pH alteration in the skin or upregulation of reactive oxygen species or enzymes, can be utilized to create drug delivery systems that specifically target the diseased skin to achieve a better efficacy and safety. In the latter context, however, it is of key importance to match the trigger mechanism of the drug delivery system to the actual pathological features of the specific skin condition. Hence, the focus of this article is placed not only on reviewing stimuli-responsive drug delivery systems developed to treat specific inflammatory skin conditions, but also on critically evaluating their efficacy in the context of specific skin diseases. STATEMENT OF SIGNIFICANCE: Skin diseases affect one-third of the world's population, significantly lowering the quality of life of the patients, who deal with symptoms such as painful and itchy skin lesions, as well as stigmatization due to the visibility of their symptoms. Current treatments for inflammatory skin conditions are often hampered by low patient adherence or serious drug side effects. Therefore, more emphasis should be placed on developing innovative formulations that provide better efficacy and safety for patients. Stimuli-responsive drug delivery systems hold considerable promise in this regard, as they can deliver their cargo precisely where and when it is needed, reducing adverse effects and potentially offering better treatment outcomes.

Sensors and Devices Guided by Artificial Intelligence for Personalized Pain Medicine

Personalized pain medicine aims to tailor pain treatment strategies for the specific needs and characteristics of an individual patient, holding the potential for improving treatment outcomes, reducing side effects, and enhancing patient satisfaction. Despite existing pain markers and treatments, challenges remain in understanding, detecting, and treating complex pain conditions. Here, we review recent engineering efforts in developing various sensors and devices for addressing challenges in the personalized treatment of pain. We summarize the basics of pain pathology and introduce various sensors and devices for pain monitoring, assessment, and relief. We also discuss advancements taking advantage of rapidly developing medical artificial intelligence (AI), such as AI-based analgesia devices, wearable sensors, and healthcare systems. We believe that these innovative technologies may lead to more precise and responsive personalized medicine, greatly improved patient quality of life, increased efficiency of medical systems, and reducing the incidence of addiction and substance use disorders.

Impact of professional experience on clinical judgment and muscular response in various neuromuscular tests

Muscle testing is an integral component in assessing musculoskeletal function and tailoring rehabilitation efforts. This study aimed i. to identify an objective evaluation system sensitive to analyze changes in different muscular conditions in different neuromuscular tests across a spectrum of professional experience levels; and ii. to analyze differences in objective parameters and clinical judgment between participants of different levels of expertise in different muscular conditions in different neuromuscular tests. Participants included 60 subjects with Level I to III expertise who performed blinded neuromuscular tests on the middle deltoid and rectus femoris muscles of 40 volunteer subjects. The methodology centered on standardizing test protocols to minimize variability, employing EMG to quantify muscle activity, thermography to capture thermographic muscular response, and digital dynamometry to measure muscular resistance. The findings revealed that while traditional methods like thermography and electromyography provide valuable insights, digital dynamometry stands out for its sensitivity in detecting muscle condition changes in neuromuscular test. Moreover, the data underscored the pivotal role of advanced training and expertise in enhancing the precision and accuracy of neuromuscular diagnostics, since there were significant differences in objective parameters and clinical judgment between participants of different levels of expertise in the different muscular conditions in Middle deltoid and Rectus femoris neuromuscular tests analyzed, presenting higher expertise participant clinical judgment like objective validated instrument.

Cannabidiol plus krill oil supplementation improves chronic stifle osteoarthritis in dogs: A double-blind randomized controlled trial

Osteoarthritis (OA) is the most common orthopedic disorder characterized by chronic inflammation and pain in dogs and cats. Cannabis spp. contains cannabidiol (CBD), a substance with pain relief and anti-inflammatory properties in different animals including dogs with OA. The use of CBD supplements has been increasingly intertwining in veterinary medicine. This study aimed to evaluate the clinical efficacy of CBD + krill oil-supplemented biscuit against canine OA. In total, 30 dogs with stifle OA were randomized and divided into the placebo, krill oil, and CBD + krill oil groups. The Canine Brief Pain Inventory questionnaire was used to evaluate the efficacy of each treatment against pain. Stifle temperature was monitored to identify degrees of stifle inflammation. Two and one dogs in the placebo group were excluded from the study due to worsening lameness and increased pain interference score (PIS) and pain severity score (PSS) at days 14 and 28, respectively. The PIS and PSS scores of the krill oil and CBD + krill oil groups gradually and significantly improved after two weeks of treatment. The CBD + krill oil group had better PIS and PSS scores than the placebo and krill oil groups. However, there was no statistically significant difference in the PIS and PSS scores between the krill oil and CBD + krill oil groups. The stifle temperature of the three groups at different periods did not significantly differ. In conclusion, CBD + krill oil supplements are safe against canine OA. CBD can reduce pain and inflammation.

Use of Non-Thermal Plasma as Postoperative Therapy in Anal Fistula: Clinical Experience and Results

Anal fistula, characterized by abnormal tracts between the perianal skin and the anal canal, presents challenges in treatment because of its diversity and complexity. This study investigates the use of non-thermal plasma as a postsurgical therapy for anal fistula, aiming to promote healing and tissue regeneration. A specialized plasma reactor was designed to apply non-thermal plasma within the anorectal cavity practically. Non-thermal plasma treatment was administered to 20 patients including 10 undergoing fistulectomies and 10 undergoing fistulotomies. The average duration of non-thermal plasma application in the operating room was shorter for fistulotomies. The pain reported the day after surgery was similar in both groups. Improvements in the number of evacuations starting from the day after surgery, as well as the assessment of stool quality using the Bristol scale, indicated satisfactory intestinal recovery. Fistulotomy patients exhibited faster wound healing times. These findings underscore the efficacy of non-thermal plasma as a postoperative therapy for anal fistula, enhancing healing and recovery outcomes without increasing complication risks.

Short-term effects of 448 kilohertz radiofrequency stimulation on plantar fascia measured by quantitative ultrasound elastography and thermography on active healthy subjects: an open controlled clinical trial

Objective: This study is an open clinical trial. The aim of this study was to show the changes that occur in the viscoelastic properties of the plantar fascia (twenty healthy volunteers) measured by SEL and the changes in the plantar fascia temperature measured by thermography after the application of a 448 kHz capacitive resistive monopolar radiofrequency (CRMR) in active healthy subjects immediately after treatment and at the 1-week follow-up.

Methods: Furthermore, to analyze if an intervention with 448 kHz CRMR in the plantar fascia of the dominant lower limb produces a thermal response in the plantar fascia of the non-dominant lower limb. The final objective was to analyze the level of association between the viscoelastic properties of the PF and the temperature before and after the intervention with 448 kHz CRMR.

Results: Our results showed that a temperature change, which was measured by thermography, occurred in the plantar fascia after a single intervention (T0-T1) and at the 1-week follow up (T1-T2).

Conclusion: However, no changes were found in the viscoelastic properties of the plantar fascia after the intervention or at the 1-week follow up. This is the first study to investigate changes in both plantar fascia viscoelastic properties and in plantar fascia temperature after a radiofrequency intervention.

Advancing DIEP Flap Monitoring with Optical Imaging Techniques: A Narrative Review

OBJECTIVES

This review aims to explore recent advancements in optical imaging techniques for monitoring the viability of Deep Inferior Epigastric Perforator (DIEP) flap reconstruction. The objectives include highlighting the principles, applications, and clinical utility of optical imaging modalities such as near-infrared spectroscopy (NIRS), indocyanine green (ICG) fluorescence angiography, laser speckle contrast imaging (LSCI), hyperspectral imaging (HSI), dynamic infrared thermography (DIRT), and short-wave infrared thermography (SWIR) in assessing tissue perfusion and oxygenation. Additionally, this review aims to discuss the potential of these techniques in enhancing surgical outcomes by enabling timely intervention in cases of compromised flap perfusion.

MATERIALS AND METHODS

A comprehensive literature review was conducted to identify studies focusing on optical imaging techniques for monitoring DIEP flap viability. We searched PubMed, MEDLINE, and relevant databases, including Google Scholar, Web of Science, Scopus, PsycINFO, IEEE Xplore, and ProQuest Dissertations & Theses, among others, using specific keywords related to optical imaging, DIEP flap reconstruction, tissue perfusion, and surgical outcomes. This extensive search ensured we gathered comprehensive data for our analysis. Articles discussing the principles, applications, and clinical use of NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR in DIEP flap monitoring were selected for inclusion. Data regarding the techniques' effectiveness, advantages, limitations, and potential impact on surgical decision-making were extracted and synthesized.

RESULTS

Optical imaging modalities, including NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR offer a non- or minimal-invasive, real-time assessment of tissue perfusion and oxygenation in DIEP flap reconstruction. These techniques provide objective and quantitative data, enabling surgeons to monitor flap viability accurately. Studies have demonstrated the effectiveness of optical imaging in detecting compromised perfusion and facilitating timely intervention, thereby reducing the risk of flap complications such as partial or total loss. Furthermore, optical imaging modalities have shown promise in improving surgical outcomes by guiding intraoperative decision-making and optimizing patient care.

CONCLUSIONS

Recent advancements in optical imaging techniques present valuable tools for monitoring the viability of DIEP flap reconstruction. NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR offer a non- or minimal-invasive, real-time assessment of tissue perfusion and oxygenation, enabling accurate evaluation of flap viability. These modalities have the potential to enhance surgical outcomes by facilitating timely intervention in cases of compromised perfusion, thereby reducing the risk of flap complications. Incorporating optical imaging into clinical practice can provide surgeons with objective and quantitative data, assisting in informed decision-making for optimal patient care in DIEP flap reconstruction surgeries.

Noncontact Sensors for Vital Signs Measurement: A Narrative Review

Vital signs are crucial for monitoring changes in patient health status. This review compared the performance of noncontact sensors with traditional methods for measuring vital signs and investigated the clinical feasibility of noncontact sensors for medical use. We searched the Medical Literature Analysis and Retrieval System Online (MEDLINE) database for articles published through September 30, 2023, and used the key search terms "vital sign," "monitoring," and "sensor" to identify relevant articles. We included studies that measured vital signs using traditional methods and noncontact sensors and excluded articles not written in English, case reports, reviews, and conference presentations. In total, 129 studies were identified, and eligible articles were selected based on their titles, abstracts, and full texts. Three articles were finally included in the review, and the types of noncontact sensors used in each selected study were an impulse radio ultrawideband radar, a microbend fiber-optic sensor, and a mat-type air pressure sensor. Participants included neonates in the neonatal intensive care unit, patients with sleep apnea, and patients with coronavirus disease. Their heart rate, respiratory rate, blood pressure, body temperature, and arterial oxygen saturation were measured. Studies have demonstrated that the performance of noncontact sensors is comparable to that of traditional methods of vital signs measurement. Noncontact sensors have the potential to alleviate concerns related to skin disorders associated with traditional skin-contact vital signs measurement methods, reduce the workload for healthcare providers, and enhance patient comfort. This article reviews the medical use of noncontact sensors for measuring vital signs and aimed to determine their potential clinical applicability.

Knee temperature remains abnormal in patients successfully treated with anterior cruciate ligament reconstruction: An infrared thermography analysis

Purpose

The aim of this study was to evaluate if the operated knee environment remains abnormal in patients successfully treated with anterior cruciate ligament reconstruction (ACL-R).

Methods

Thirty asymptomatic patients were enrolled (28 men, 2 women, age 28.6 ± 6.54 years, body mass index: 24.9 ± 3.0 kg/m2) and evaluated at 42.2 ± 12.5 months after surgery. Patients were assessed with patient-reported outcome measurements and with a triaxial accelerometer. The temperature of the knees as well as four regions of interest were evaluated with an infrared thermographic camera FLIR T1020 (FLIR® Systems) according to a standardised protocol including a baseline evaluation and further evaluations immediately after exercise and after 5, 10 and 20 min. The temperature of the ACL-R knee was compared to that of the contralateral healthy knee for the purpose of the study.

Results

The mean temperature of the knee was higher (p = 0.010) for the ACL-R knees (31.4 ± 1.4°C) compared to the healthy knees (31.1 ± 1.6°C), as well as for the patellar area (p = 0.005), the lateral area (p = 0.016) and the medial area (p = 0.014). The analysis of the response to the exercises of the ACL-R knees showed similar trends to the healthy knees but higher temperature values at all time points (p < 0.05). Patients who underwent ACL-R with concomitant meniscal treatment showed higher knee temperatures compared to ACL-R knees without concomitant meniscal treatment after 5 (p = 0.047), 10 (p = 0.027) and 20 min (p = 0.048).

Conclusions

The temperature of asymptomatic knees previously treated with ACL-R is higher than the contralateral healthy knee, both at rest and after exercise, with a further increase in knees that underwent both ACL-R and meniscal treatment. These results suggest an inflammatory state persisting years after the surgery, which could predispose to the early onset of knee degeneration.

Level of Evidence

III, Case-control study.

Neurectomy of the Nerve of Henle Associated with Periarterial Sympathectomy for Management of Intractable Raynaud Phenomenon

BACKGROUND

In periarterial sympathectomy for intractable Raynaud phenomenon, the extent of adventitectomy and postoperative outcomes and hand perfusion assessment tools remain debatable. The authors evaluated the outcome of neurectomy of the nerve of Henle combined with ulnar tunnel release and periarterial adventitectomy in the treatment of refractory Raynaud phenomenon using objective measurements and patient-reported outcomes.

METHODS

Nineteen patients with 20 affected hands were prospectively enrolled and underwent the proposed procedures from 2015 to 2021. Relevant data, including Michigan Hand Outcomes Questionnaire and 36-Item Short Form health questionnaire scores, were documented for analysis during a 3-year follow-up.

RESULTS

The average ingress value of the three measured fingers (index, long, and ring) on indocyanine green angiography increased after surgery ( P = 0.02). The median number of ulcers decreased ( P < 0.001), and the median digital skin temperature increased ( P < 0.001). Questionnaire scores showed improvement in physical aspects, such as overall hand function ( P ≤ 0.001), activities of daily living ( P = 0.001), work performance ( P = 0.02), pain ( P < 0.001), physical function ( P = 0.053), and general health ( P = 0.048), and mental aspects, such as patient satisfaction ( P < 0.001) and mental health ( P = 0.001). The average indocyanine green ingress value of the three measured fingers significantly correlated with the patient-reported outcomes, including overall hand function ( r = 0.46, P = 0.04), work performance ( r = 0.68, P = 0.001), physical function ( r = 0.51, P = 0.02), and patient satisfaction ( r = 0.35, P= 0.03).

CONCLUSIONS

The proposed surgical procedures provided satisfactory outcomes, both subjectively and objectively, over a follow-up period of up to 3 years. Indocyanine green angiography may provide rapid and quantitative measurements for perioperative hand perfusion assessment.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Chronic Pain and Joint Hypermobility: A Brief Diagnostic Review for Clinicians and the Potential Application of Infrared Thermography in Screening Hypermobile Inflamed Joints

Joint hypermobility syndromes, particularly chronic pain associated with this condition, including Hypermobile Ehlers-Danlos Syndrome (hEDS) and Hypermobility Spectrum Disorders (HSD), present diagnostic challenges due to their multifactorial origins and remain poorly understood from biomechanical and genomic-molecular perspectives. Recent diagnostic guidelines have differentiated hEDS, HSD, and benign joint hypermobility, providing a more objective diagnostic framework. However, incorrect diagnoses and underdiagnoses persist, leading to prolonged journeys for affected individuals. Musculoskeletal manifestations, chronic pain, dysautonomia, and gastrointestinal symptoms illustrate the multifactorial impact of these conditions, affecting both the physical and emotional well-being of affected individuals. Infrared thermography (IRT) emerges as a promising tool for joint assessment, especially in detecting inflammatory processes. Thermal distribution patterns offer valuable insights into joint dysfunctions, although the direct correlation between pain and inflammation remains challenging. The prevalence of neuropathies among hypermobile individuals accentuates the discordance between pain perception and thermographic findings, further complicating diagnosis and management. Despite its potential, the clinical integration of IRT faces challenges, with conflicting evidence hindering its adoption. However, studies demonstrate objective temperature disparities between healthy and diseased joints, especially under dynamic thermography, suggesting its potential utility in clinical practice. Future research focused on refining diagnostic criteria and elucidating the underlying mechanisms of hypermobility syndromes will be essential to improve diagnostic accuracy and enhance patient care in this complex and multidimensional context.

Exploring Thermal Dynamics in Wound Healing: The Impact of Temperature and Microenvironment

Exploring the critical role of thermal dynamics in wound healing, this manuscript navigates through the complex biological responses initiated upon wound infliction and how temperature variations influence the healing trajectory. Integrating biothermal physics, clinical medicine, and biomedical engineering, it highlights the significance of thermal management in wound care, emphasizing the wound microenvironment's division into internal and external domains and their collaborative impact on tissue repair. Innovations in real-time wound temperature monitoring, especially through intelligent wireless sensor dressings, are spotlighted as transformative, enabling precise wound condition management. The text underscores the necessity for further research to elucidate thermal regulation's molecular and cellular mechanisms on healing processes. It advocates for standardized protocols for localized heating treatments, integrating them into personalized wound care strategies to enhance therapeutic outcomes, improve patient well-being, and achieve cost-effective healthcare practices. This work presents a forward-looking perspective on refining wound management through sophisticated, evidence-based interventions, emphasizing the interplay between thermal dynamics and wound healing.

A systematic review of the exercise effects on burn wound healing

The emerging evidence has indicated the role of microRNAs (miRNA) in various physiological or pathological processes. Also, documents have suggested that exercise, by affecting miRNA regulation, may enhance burn wound healing. The current study aims to systematically review the role of exercise in regulating miRNAs related to burn wound healing to provide potential therapeutic targets. A comprehensive, systematic search was performed in different international electronic databases, such as Embase, PubMed and Google Scholar search engine, Science Direct, ProQuest and Ovid using keywords extracted from Medical Subject Headings from 2010 to September 2023. The keywords, including 'exercise' AND 'burn wound' AND 'microRNA' and finally, six cases were achieved. Evidence has indicated that exercise may promote the healing of burn wounds by regulating certain miRNAs. Studies have found that exercise regulates the expression of miRNAs such as mir-155, miR-21, let-7a, miR-146a, miR-122 and mir-210 in burn wound tissue, which regulate inflammation and angiogenesis. These findings suggest that miRNAs may play a role in the positive effect of exercise on burn wound healing. However, further research is needed to understand the mechanisms involved fully.

Thermal Imaging as a Method to Indirectly Assess Peripheral Vascular Integrity and Tissue Viability in Veterinary Medicine: Animal Models and Clinical Applications

Infrared thermography (IRT) is a technique that indirectly assesses peripheral blood circulation and its resulting amount of radiated heat. Due to these properties, thermal imaging is currently applied in human medicine to noninvasively evaluate peripheral vascular disorders such as thrombosis, thromboembolisms, and other ischemic processes. Moreover, tissular damage (e.g., burn injuries) also causes microvasculature compromise. Therefore, thermography can be applied to determine the degree of damage according to the viability of tissues and blood vessels, and it can also be used as a technique to monitor skin transplant procedures such as grafting and free flaps. The present review aims to summarize and analyze the application of IRT in veterinary medicine as a method to indirectly assess peripheral vascular integrity and its relation to the amount of radiated heat and as a diagnostic technique for tissue viability, degree of damage, and wound care.

Utility of Thermographic Imaging for Callus Identification in Wound and Foot Care

Calluses are thickened skin areas that develop due to repeated friction, pressure, or other types of irritation. While calluses are usually harmless and formed as a protective surface, they can lead to skin ulceration or infection if left untreated. As calluses are often not clearly visible to the patients, and some areas of dead skin can be missed during debridement, accessory tools can be useful in assessment and follow-up. The practical question addressed in this article is whether or not thermal imaging adds value to callus assessment. We have performed a theoretical analysis of the feasibility of thermographic imaging for callus identification. Our analytical calculations show that the temperature drop in the epidermis should be on the order of 0.1 °C for the normal epidermis in hairy skin, 0.9 °C for glabrous skin, and 1.5-2 °C or higher in calluses. We have validated our predictions on gelatin phantoms and demonstrated the feasibility of thermographic imaging for callus identification in two clinical case series. Our experimental results are in agreement with theoretical predictions and support the notion that local skin temperature variations can indicate epidermis thickness variations, which can be used for callus identification. In particular, a surface temperature drop on the order of 0.5 °C or more can be indicative of callus presence, particularly in callus-prone areas. In addition, our analytical calculations and phantom experiments show the importance of ambient temperature measurements during thermographic assessments.

Pressure pain sensitivity, thermographic changes, function, life and sleep quality in patients with unilateral rotator cuff injury: A case-control study

INTRODUCTION-AIM

This study aimed to assess pressure pain sensitivity, thermographic changes, functional status, quality of life, and sleep in individuals with unilateral shoulder pain due to rotator cuff tear and compare these parameters with the unaffected side and asymptomatic individuals.

MATERIAL-METHOD

Thirty-two patients with unilateral rotator cuff injury and 32 volunteers without shoulder problems were included. Pain was evaluated using a visual analogue scale, pressure pain sensitivity with a digital algometer, thermographic changes with a thermal camera, upper extremity function through the Disabilities of the Arm, Shoulder, and Hand Disability Questionnaire, sleep quality using the Pittsburgh Sleep Quality Index, and quality of life using SF-36.

RESULTS

Pressure pain sensitivity of the deltoideus, supraspinatus, and subscapularis muscles in the affected limb was lower than in the unaffected limb (p = 0.027, p = 0.005, p < 0.001). Conversely, pressure sensitivity of the deltoideus, biceps brachii, and subscapularis muscles was higher in the patient group (p = 0.008, p = 0.042, p < 0.001). Furthermore, a decrease in temperature was observed in all patients, except for the trapezius muscles of the affected side (p < 0.05).

CONCLUSION

This study sheds light on altered pressure pain sensitivity and thermographic changes in individuals with unilateral shoulder pain due to rotator cuff tear. Additionally, the study highlights impairments in functional status, quality of life, and sleep in these individuals, emphasizing the broader impact of such injuries. Targeted interventions based on these findings have the potential to enhance overall well-being and functional outcomes for affected individuals.

LEVEL OF EVIDENCE

Level III, Case-control study, prognosis study.

[Deep Learning-Based Identification of Common Complication Features of Surgical Incisions]

Objective

In recent years, due to the development of accelerated recovery after surgery and day surgery in the field of surgery, the average length-of-stay of patients has been shortened and patients stay at home for post-surgical recovery and healing of the surgical incisions. In order to identify, in a timely manner, the problems that may appear at the incision site and help patients prevent or reduce the anxiety they may experience after discharge, we used deep learning method in this study to classify the features of common complications of surgical incisions, hoping to realize patient-directed early identification of complications common to surgical incisions.

Methods

A total of 1 224 postoperative photographs of patients' surgical incisions were taken and collected at a tertiary-care hospital between June 2021 and March 2022. The photographs were collated and categorized according to different features of complications of the surgical incisions. Then, the photographs were divided into training, validation, and test sets at the ratio of 8∶1∶1 and 4 types of convolutional neural networks were applied in the training and testing of the models.

Results

Through the training of multiple convolutional neural networks and the testing of the model performance on the basis of a test set of 300 surgical incision images, the average accuracy of the four ResNet classification network models, SE-ResNet101, ResNet50, ResNet101, and SE-ResNet50, for surgical incision classification was 0.941, 0.903, 0.896, and 0.918, respectively, the precision was 0.939, 0.898, 0.868, and 0.903, respectively, and the recall rate was 0.930, 0.880, 0.850, and 0.894, respectively, with the SE-Resnet101 network model showing the highest average accuracy of 0.941 for incision feature classification.

Conclusion

Through the combined use of deep learning technology and images of surgical incisions, problematic features of surgical incisions can be effectively identified by examining surgical incision images. It is expected that patients will eventually be able to perform self-examination of surgical incisions on smart terminals.

Application of intraoperative infrared thermography in bypass surgery for adult moyamoya syndrome: A preliminary study

Background and objectives

Cerebral revascularization surgery is the mainstay of treatment for moyamoya syndrome (MMS) today, and intraoperative determination of the patency of the revascularized vessel is a critical factor in the success of the procedure. Currently, major imaging modalities include intraoperative indocyanine green (ICG) videoangiography (ICG-VA), digital subtraction angiography (DSA), and vascular ultrasound Doppler. Infrared thermography is a modern imaging modality with non-contact devices for the acquisition and analysis of thermal data. We aimed to investigate the feasibility and advantages of infrared thermography in determining anastomotic patency during MMS surgery.

Methods

Indocyanine green videoangiography and infrared thermography were performed simultaneously in 21 patients with MMS who underwent bypass surgery. The detection result of vessel patency was compared, and the feasibility and advantages of infrared thermography were assessed.

Results

The patency of the anastomosis was accurately determined in 21 patients using either ICG angiography or infrared thermography. In 20 patients, the results of infrared thermography showed that the vascular anastomosis was unobstructed, and there was an agreement with the subsequent results of ICG-VA. In one patient, we suspected inadequate patency after testing the anastomosis with infrared thermography, and the results of ICG-VA evaluation of the anastomosis confirmed that there was indeed an anastomotic obstruction.

Conclusion

Compared with ICG-VA, infrared thermography might offer an alternative non-invasive, contrast-free option in assessing anastomosis patency compared with ICG-VA, and it is likely to become more widely used in the clinic in the near future.

Infrared Thermography in Symptomatic Knee Osteoarthritis: Joint Temperature Differs Based on Patient and Pain Characteristics

The aim of this study was to evaluate osteoarthritis (OA) patients with infrared thermography to investigate imaging patterns as well as demographic and clinical characteristics that influence knee inflammation. Forty patients with one-sided symptomatic knee OA were included and evaluated through knee-specific PROMs and the PainDETECT Questionnaire for neuropathic pain evaluation. Thermograms were captured using a thermographic camera FLIR-T1020 and temperatures were extracted using the software ResearchIR for the overall knee and the five ROIs: medial, lateral, medial patella, lateral patella, and suprapatellar. The mean temperature of the total knee was 31.9 ± 1.6 °C. It negatively correlated with age (rho = −0.380, p = 0.016) and positively correlated with BMI (rho = 0.421, p = 0.007) and the IKDC objective score (tau = 0.294, p = 0.016). Men had higher temperatures in the knee medial, lateral, and suprapatellar areas (p = 0.017, p = 0.019, p = 0.025, respectively). Patients with neuropathic pain had a lower temperature of the medial knee area (31.5 ± 1.0 vs. 32.3 ± 1.1, p = 0.042), with the total knee negatively correlating with PainDETECT (p = 0.045). This study demonstrated that the skin temperature of OA symptomatic knees is influenced by demographic and clinical characteristics of patients, with higher joint temperatures in younger male patients with higher BMI and worst objective knee scores and lower temperatures in patients affected by neuropathic pain.

Intra- and inter-session reliability and repeatability of an infrared thermography device designed for materials to measure skin temperature of the triceps surae muscle tissue of athletes

Background

Infrared thermography devices have been commonly applied to measure superficial temperature in structural composites and walls. These tools were cheaper than other thermographic devices used to measure superficial human muscle tissue temperature. In addition, infrared thermography has been previously used to assess skin temperature related to muscle tissue conditions in the triceps surae of athletes. Nevertheless, the reliability and repeatability of an infrared thermography device designed for materials, such as the Manual Infrared Camera PCE-TC 30, have yet to be determined to measure skin temperature of the triceps surae muscle tissue of athletes.

Objective

The purpose was to determine the procedure's intra- and inter-session reliability and repeatability to determine skin temperature within the Manual Infrared Camera PCE-TC 30 thermography device in the triceps surae muscle tissue of athletes, which was initially designed to measure the superficial temperature of materials.

Methods

A total of 34 triceps surae muscles were bilaterally assessed from 17 healthy athletes using the Manual Infrared Camera PCE-TC 30 thermography device to determine intra- (at the same day separated by 1 h) and inter-session (at alternate days separated by 48 h) reliability and repeatability of the skin temperature of the soleus, medial and lateral gastrocnemius muscles. The triceps surae complex weas measured by a region of interest of 1 cm² through five infrared thermography images for each muscle. Statistical analyses comprised intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimum detectable change (MCD), systematic error of measurement, correlation (r), and Bland-Altman plots completed with linear regression models (R ²).

Results

Intra- and inter-session measurements of the proposed infrared thermography procedure showed excellent reliability (ICC_(1,2) = 0.968-0.977), measurement errors (SEM = 0.186-0.232 °C; MDC = 0.515-0.643 °C), correlations (r = 0.885-0.953), and did not present significant systematic error of measurements (P > 0.05). Adequate agreement between each pair of measurement moments was presented by the Bland-Altman plots according to the limits of agreement and non-significant linear regression models (R ² = 0.000-0.019; P > 0.05).

Conclusions

The proposed procedure to determine skin temperature within the Manual Infrared Camera PCE-TC 30 thermography device presented excellent intra- and inter-session reliability and repeatability in athletes' triceps surae muscle tissue. Future studies should consider the SEM and MDC of this procedure to measure the skin temperature of soleus, medial, and lateral gastrocnemius muscles to promote triceps surae muscle prevention and recovery in athletes.

Skin temperature normalizes faster than pressure pain thresholds, pain intensity, and pain distribution during recovery from eccentric exercise

INTRODUCTION

Acute musculoskeletal injuries have diverse symptomatology and a multidimensional recovery process, including changes in swelling, redness, hyperalgesia, and expanded pain distribution. In a small proportion of cases, the tissue heals, although these symptoms persist, reflecting altered peripheral and central pain mechanisms. However, the otherwise healthy multidimensional recovery process following damage and pain is less than clear. The objective was to assess mechanical muscle hyperalgesia, skin temperature, and pain intensity and distribution during the recovery process in response to eccentric exercise in the hamstring muscles.

METHODS

Twenty-four healthy males participated in four sessions (Day-0, Day-2, Day-4, and Day-7). Exercise-induced muscle soreness was induced on Day-0 by five sets of 20 repetitions of an eccentric exercise involving the hamstrings on the dominant leg. Each session included assessments of thermography, pressure pain thresholds (PPTs), pain intensity, and area of exercise-induced pain.

RESULTS

Decreased PPTs (P < 0.005), higher pain intensity (P < 0.001), and a larger area of pain (P < 0.001) were displayed on Day-2 and Day-4 than Day-0. Skin temperature decreased on Day-2 than Day-0 (P < 0.01) and returned to baseline assessments by Day-4, despite lower temperature than the contralateral tight (P < 0.01). Further, there was a positive correlation between pain intensity and area on Day-2 and Day-4 (P < 0.005), but no for changes in skin temperature.

CONCLUSION

Thermographic changes and pain-related variables altered following eccentric exercise demonstrate different recovery times. These results provide insights into potential mechanisms and measures that can be used to assess recovery from exercise-induced damage.

Skin Temperature: The Impact of Perfusion, Epidermis Thickness, and Skin Wetness

This work aimed to elucidate the primary factors which affect skin temperature. A simple thermophysical model of the skin, which accounts for radiative, convective, and evaporative heat losses, has been developed to address it. The model is based on the skin’s morphology and consists of passive (nonviable tissue) and active (viable tissue) layers. The bioheat equation was solved for these layers using realistic assumptions. It was found that other than the ambient temperature, blood perfusion and epidermis thickness are the primary factors responsible for the skin temperature variations. The main temperature drop in the skin is attributed to the cooling of the blood in the venous plexus. The temperature drop in the epidermis is on the scale of 0.1 °C for the normal epidermis but can be 1.5–2 °C or higher in calluses. Thus, local skin temperature variations can indicate the epidermis thickness variations, particularly in callus-prone areas. The effects of relative air humidity and skin wetness on skin temperature were also quantified. The presence of free moisture on the skin (e.g., wet wound) significantly increases the heat transfer, resulting in a skin temperature drop, which can be on the scale of several degrees Celsius. The relative air humidity significantly contributes (by slowing heat dissipation) only in the case of evaporative heat loss from wet skin. Therefore, wet skin is undesirable and should be avoided during a thermographic assessment.

Preparing infection detection technology for hospital at home after lower limb external fixation

Background

Patients with severe bone fractures and complex bone deformities are treated by orthopedic surgeons with external fixation for several months. During this long treatment period, there is a high risk of inflammation and infection at the superficial skin area (pin site). This can develop into a devastating, sometimes fatal, and always costly condition of deep bone infection.

Objective

For pin site infection surveillance, thermography technology could be the solution to build an objective and continuous home-based remote monitoring tool to avoid frequent nursing care and hospital visits. However, future studies of infection monitoring require a preliminary step to automate the process of locating and detecting the pin sites in thermal images reliably for temperature measurement, and this step is the aim of this study.

Methods

This study presents an automatic approach for identifying and annotating pin sites on visible images using bounding boxes and transferring them to the corresponding thermal images for temperature measurement. The pin site is detected by applying deep learning-based object detection architecture YOLOv5 with a novel loss evaluation and regression method, control distance intersection over union. Furthermore, we address detecting pin sites in a practical environment (home setting) accurately through transfer learning.

Results and conclusion

The proposed model offers the pin site detection in 1.8 ms with a high precision of 0.98 and enables temperature information extraction. Our work for automatic pin site annotation on thermography paves the way for future research on infection assessment on thermography.