Differential knee skin temperature following total knee arthroplasty and its relationship with serum indices and outcome: A prospective study

Synthesis of Temperature Sensing Nitrogen-Doped Carbon Dots and Their Application in Fluorescent Ink

With the discovery of research, many properties of carbon dots are getting better and better. People have taken advantage of this and utilized them interspersed in various fields. In the present study, water-soluble nitrogen-doped carbon dots (N-CDs) with excellent optical and fluorescence thermal properties were prepared by the hydrothermal method using 4-dimethylaminopyridine and N,N'-methylenebisacrylamide as precursors. Co2+ has a selective bursting effect on the fluorescence of N-CDs. The fluorescence of N-CDs is selectively burst by Co2+, and the high sensitivity is good in the range of 0-12 μM with a detection limit of 74 nM. In addition, the good temperature response (reversible and recoverable fluorescence in the temperature range of 20~90 °C) and excellent optical properties of the N-CDs also make them new potentials in the field of fluorescent inks and temperature sensing.

Natural history of changes in knee skin temperature following total knee arthroplasty: a systematic review and meta-analysis

Patients undergoing total-knee arthroplasty (TKA) have transient increases in anterior knee skin temperature (ST) that subside as recovery progresses-except in cases of systemic or local prosthetic joint infections (PJI). This meta-analysis was designed to quantify the changes in knee ST following TKA in patients with uncomplicated recovery as a prerequisite for assessing the usefulness of thermal imaging for diagnosis of PJI. This meta-analysis (PROSPERO-CRD42021269864) was performed according to PRISMA guidelines. PUBMED and EMBASE were searched for studies reporting knee ST of patients that underwent unilateral TKA with uncomplicated recovery. The primary outcome was the weighted means of the differences in ST between the operated and the non-operated knees (ΔST) for each time point (before TKA, and 1 day; 1,2, and 6 weeks; and 3,6, and 12-months post-TKA). For this analysis, 318 patients were included from 10 studies. The elevation in ST was greatest during the first 2-weeks (ΔST = 2.8 °C) and remained higher than pre-surgery levels at 4-6 weeks. At 3-months, ΔST was 1.4 °C. It decreased to 0.9 °C and 0.6 °C at 6 and 12-months respectively. Establishing the baseline profile of knee ST following TKA provides the necessary first step for evaluating the usefulness of thermography for the diagnosis of post-procedural PJI.

Thermal imaging in total knee replacement and its relation with inflammation markers

Total knee replacement is an end-stage surgical treatment of osteoarthritis patients to improve their quality of life. The study presents a thermal imaging-based approach to assess the recovery of operated-knees. The study focuses on the potential of thermal imaging for total knee replacement and its relation with clinical inflammatory markers. A total of 20 patients with bilateral knee replacement were included for thermal imaging and serology, where data was acquired on pre-operative day and five post-operative days. To quantify the inflammation, the temperature-based parameters (like mean differential temperature, relative percentage of raised temperature) were evaluated from thermal images, while the clinically proven inflammation markers were obtained from blood samples for clinical validation. Initially, the knee region was segmented by applying the automatic method, subsequently, the mean skin temperature was calculated and investigated for a statistical relevant relationship with inflammatory markers. After surgery, the mean skin temperature was first increased (>2.15 ℃ for different views) then settled to pre-operative level by 90th day. Consequently, the mean differential temperature showed a strong correlation with erythrocyte sedimentation rate (r > 0.893) and C-reactive protein (r > 0.955). Also, the visual profile and relative percentage of raised temperature showed promising results in quantifying the temperature changes both qualitatively and quantitatively. This study provides an automatic and non-invasive way of screening the patients for raised levels of skin temperature, which can be a sign of inflammation. Hence, the proposed temperature-based technique can help the clinicians for visual assessment of post-operative recovery of patients.

Embedded sensing package for temporary bone cement spacers in infected total knee arthroplasty

The re-infection rate of total knee arthroplasty (TKA) after two stage revision (15%) remains high as it can be challenging to determine whether the infection has been fully cleared between the first and second stage procedures. Temporary embedded sensor systems could be a potential solution to indicate whether the infection has been cleared. In this study a telemetric sensor system to integrate with a bone cement spacer and measure knee joint temperature was designed and evaluated. The sensor package precision, accuracy, hysteresis, and thermal equilibrium were empirically determined. Cadaveric testing was performed with the sensor package implanted inside the femoral notch alongside a pre-formed femoral and tibial bone cement spacer. The limb was tested though 30,000 cycles at 0.5 Hz under a 500 N load. Accuracy and precision of the sensing package were found to be ±0.24 °C and 0.09 °C respectively with negligible hysteresis. Thermal insulation caused by the implant itself was found to produce a thermal time constant of 263 ± 5 s, resulting in a 17 min rise time. Memory capacity enabled data logging every 20 s for a 6 week period before necessitating data transfer. Bluetooth was suitable for data transmission while the package was implanted. Following cyclic loading of the cadaveric specimen, imaging and debridement revealed no issues related to mechanical integrity of the bone cement spacer or encapsulated sensor package. While additional validation is required before use in patients, the concept of temporary embedded sensing technology to aid management of infection treatments is promising.

Detection of skin temperature differences using palpation by manual physical therapists and lay individuals

Objectives

To evaluate the accuracy of detection of temperature differences among skin sites of lay individuals and manual physical therapists.

Methods

Forty-four manual physical therapists and 44 lay individuals were recruited. Subjects palpated two temperature-controlled surfaces that ranged in temperature between 30 and 35 °C and varied randomly by 1, 2, 3, 4, or 5 °C for 10 s. The subjects were then asked to identify the warmer pad.

Results

Accuracy increased with larger temperature differences. Accuracy of detection of 1 and 3 °C temperature differences was higher in manual physical therapists than lay individuals.

Discussion

Palpation can be used to accurately detecting temperature differences between sites and is more accurately performed by an experienced practitioner.

Level of Evidence

3b.