The knee joint is one of the largest and most complex joints in the human body, and bio-mechanically, the joint between the femur and the tibia, which functions as the longest lever in the bone structure, can be easily damaged by various external forces . A medial collateral ligament (MCL) injury of the knee, which is caused by valgus stress on the knee, is the most common form of knee ligament injury. Also, an injury of the tibial attachment is more common than one of the femoral attachment, and in the former, an oppressive pain is the signature symptom of the medial femoral region .
Digital infrared thermographic imaging (DITI) is an examination that screens any existing disorders and any improvements or deteriorations of symptoms in the body through computer imaging that detects traces of infrared light on the surface of the skin on the human body . It is non-invasive, painless, and highly stable and avoids the risk of radiation exposure. Further, it is used as a supplemental means of diagnosis that effectively improves the understanding of the patient by displaying the results visually, and it enables an objective and quantitative evaluation of the physiological and functional states of pain [4, 5]. However, its baseline data as a diagnostic instrument are still lacking. For instance, diagnosing a symmetrical symptom or a subtle temperature difference on the surface of the body and understanding the normal body temperature are difficult due to insufficient standardized diagnostic criterion for the body’s temperature .
Studies on DITI in patient’s with osteoarthritis of the knee have been reported [7-9]; however, no research on infrared thermal imaging related to ligament injuries has been published. Thus, whether the temperature increase seen on DITI is due to the injury to the ligament or to the DITI process itself is difficult to determine. For that reason, we conducted an analysis of the temperature differences between the affected and the unaffected sides of a knee with a MCL injury by using thermography. The purpose of the present study was to determine the applicability of thermography in patient’s with a MCL injury.
Twenty patient’s with a MCL injury who underwent DITI at the Korean Medicine Hospital of Sangji University between September 2012 and June 2014 were included in this study. The patient’s information was obtained from the hospital’s medical records, and target records were selected by reviewing the medical records with the diagnostic code search terms “MCL”. We requested the data anonymously, and we extracted and analyzed data such as gender, age, final diagnosis, date of onset, present illness, physical examination, and infrared thermal image from the selected chart records. This study was approved by the institutional review board of the Korean Medicine Hospital of Sangji University (SJ IRB-14-007). The patient’s records were selected by using the following criteria: chief complaints of medial knee pain, tenderness at the MCL of the knee, positive results on the valgus stress test, and the existence of DITI data on the knee before the treatment. However, the records of some patient’s were excluded based on the following criteria: pain in both knees, arthritis (degenerative arthritis, rheumatoid arthritis, etc.,) and referred pain caused by spine disorders.
DITI was generally done before performing a physical examination and a treatment at the first visit, and a medical thermal imaging system (T-1000, Mesh Co., Wonju, Korea) was used for DITI. DITI was performed in an examination room under controlled conditions with no light and heat other than that from a fluorescent lamp and with consistent indoor air flow with no windows. During the DITI procedure, no personal were allowed to enter, leave, or move around. According to the heights of the patient’s, the measurement distances were in the range of 110 − 120 cm. The patient’s stood in comfortable positions, with their legs spread to shoulder width, and thermographic images were taken on one image around the patella. Thermography was conducted by using the routine thermography protocol of the Korean Medicine Hospital of Sangji University. The knees on the patient’s thermographic images were divided to cover 7 sub-areas: the middle of the patella (R1), and the inferomedial region (R2; Naeseuran, LE201), the inferolateral region (R3; Dokbi, ST35), the superomedial region (R4; Seulsang 2, LE108), the superolateral region (R5; Seulsang 2, LE108), the medial region (R6; Naeseulbang, LE110), and the lateral region (R7; Oeseulbang, LE110) of the patella (Fig 1).
We extracted the temperature of every region from the thermographic images of the patient’s with a MCL injury to the knee and conducted an analysis of the temperature differences between the affected and the unaffected sides by using the Wilcoxon signed rank test. Significance was set at a level of 0.05, which was associated with the 95% confidence intervals. The SPSS software package (version 19.0; SPSS, Inc, an IBM Company, Chicago, Illinois) was used for the statistical analysis.
[Fig. 1] Thermal measurement in patient’s with a medial collateral ligament injury of the knee. The thermographic image from the patient’s knee was divided into 7 areas: the middle of the patella (R1), and the inferomedial region (R2; Naeseuran), the inferolateral region (R3; Dokbi), the superomedial region (R4; Seulsang2), the superolateral region (R5; Seulsang2), the medial region (R6; Naeseulbang), and the lateral region (R7; Oeseulbang) of patella. The temperatures of all regions were measured. The right knee of the patient shows a normal thermograph, but the left knee shows an abnormal one. Thermography on a normal knee joint shows that thermal symmetry exists over the knees, the knees are colder than the adjacent areas, and a narrow temperature isotherm produces a well-shaped oval central pre-patellar zone. The regions from R2 to R7 were equidistant from R1.
[Table. 1] Distribution of sex and age
Distribution of sex and age
[Table. 2] Temperature differences, means ± standard deviations, between the affected side and the unaffected side in patient’s with medial a collateral ligament injury
Temperature differences, means ± standard deviations, between the affected side and the unaffected side in patient’s with medial a collateral ligament injury
The 20 patient’s included in the current study were composed of 14 women (70%) and 6 men (30%), with a mean age of 62.15 ± 15.71 years (mean ± standard deviation (SD)) (Table 1) The temperature of the affected side, which included R1, R2, R4, R5 and R6, showed a significant increase compared to that of the unaffected side (
Knee joint injuries occur in many circumstances, such as trauma, traffic accidents, industrial disasters or accidents. The inside of the knee joint consists of three layers: Ⅰ, Ⅱ, Ⅲ). Layer Ⅰ is a superficial layer with the sartorius and its fascia. Layer Ⅱ is the MCL, and Layer Ⅲ is the articular capsule. Among these, the MCL is located from the medial side of the femoral medial epicondyle to the edge of the tibia, and it supports the medial side of the articular capsule; however, it is vulnerable to valgus stress and can be injured together with the cruciate ligament [10, 11]. When an acute injury of the MCL occurs, it is accompanied by swelling, rigidity, and pain on the medial or the lateral side. Because the medial collateral ligament is deeply involved in the stabilization of the knee joint, any disconnection of the MCL results in instability of the joint, unlike with the lateral collateral ligament . Because recurrence and chronic pain are possible, precise assessment is needed when an injury occurs with hemarthrosis, severe exudation, or instability .
Assessment methods for a MCL injury are local tenderness, palpation of the tissue dent, the valgus stress test, magnetic resonance imaging (MRI), stress view X-rays, ultrasonography, etc. [5, 14]. Kim
DITI is an easy method that measures the temperature of the affected area and examines the degrees of hot and cold that occur with morbidity. Contrary to other diagnostic techniques, DITI makes it possible to objectify the state of the incipient disease by visualizing the temperature of the affected part. As a result, DITI has been used in various areas in the past [3-5, 16]. In Western medicine, DITI has been used to evaluate the physiological state of pain quantitatively by objectively visualizing the muscular condition and to check the progress of or the prognosis for a patient with a disease by identifying the acupoints of a body in Korean medicine .
As to diseases of the knee joint, studies have been done on the correlation of osteoarthritis to DITI. Seo
When the valgus stress is applied to the MCL, stimulation with tissue damage triggers inflammation, and the blood vessels are extended by chemical mediators such as prostaglandin, followed by increased extensions of arterioles and capillaries due to the congestion of blood flow. As a result, local heat and redness may occur.
In this study, higher superficial temperatures of R2, R4 and R6 of the affected knee adjacent to the MCL and articular capsule were observed. Furthermore, by comparison of the superficial temperatures, the extent of the injury could be visually assessed. Thus, DITI can be used as a supportive tool for the diagnosis of a MCL injury to the knee. In addition, the superficial temperatures of R1, R4 and R5 of the affected knee showed significant increases compared to that of the unaffected side (
The limitation of the study is that it was a retrospective study based on medical records, so the medical histories of the patient’s were erratic. Also, thermal images were taken during the first medical examination, so images of the knee after the pain had been alleviated were missing. Thus, we were not able to assess the changes in the thermal images after the symptoms had been alleviated correlation; neither were we able to find a correlation between the DITI and the state of the patient. Consequently, a further study should be conducted with more materials and accurately- controlled clinical parameters.
We reviewed and analyzed the records of 20 patient’s with a MCL injury of the knee who underwent DITI at the Korean Medicine Hospital of Sangji University between September 2012 and June 2014. The temperature on the affected side, which included the middle of the patella and the inferomedial region, the superomedial region, the superolateral region, and the medial region showed a significant increase compared to that on the unaffected side (