Injury follow-up from a thermographic perspective

Of all the applications of thermography in sports and health that ThermoHuman discloses (injury prevention, diagnostic support, fatigue identification, and injury monitoring), the latter probably brings together the most scientific evidence and the most solid results.

For this reason, we want to provide tools based on scientific results through the ThermoHuman software for optimal use of injury follow-up.

In November 2020, an oral communication on the most common sports injuries and their follow-up from a thermographic perspective.

This presentation served as a starting point to generate a reference database on the behaviour of thermal asymmetries in the most common musculoskeletal injuries. Unfortunately, the scientific literature hardly has published results that help us to determine the most common trend in injuries as typical as an ankle sprain, a fracture, a muscle tear, or an Anterior Cruciate Ligament injury. From ThermoHuman we have proposed to use these published results, improve them, and update them with more recent cases and implement a block in the software focused on lesion monitoring.

For this, it is essential to indicate a lesion and its location in the software. A block called Evolution of lesion automatically appears in the individual follow-up report where a graph appears that allows the comparing of the evolution of the individual’s lesion with the evolution of the ThermoHuman database, and thus being able to determine with a greater objective and visual accuracy if the evolution of the lesion is on the right track (as can be seen in the following image)

Figure 1. Example of the lesion follow-up block of a case of Biceps femoris injury with the evolution of the asymmetry of the affected central back thigh (orange line) and the evolution with a confidence margin (grey area) generated based on the database.

The software currently has four types of tracking patterns described for lesions:

• Follow-up of the anterior cruciate ligament injury, to identify the behaviour of the knee in recovery (based on 102 individuals and 455 recorded sessions).
• Ankle sprain follow-up, where we understand that the tissue will behave in a similar way in other sprains (32 cases and 222 sessions).
• Monitoring of hamstring muscle tears, which, like sprains, can be applied to other muscle injuries (based on 25 cases and 134 sessions).
• Bone fracture, where the bone behaves in a similar way in all regions of the body (mainly based on the article by Haluzan et al 2015)

Follow-up of Anterior Cruciate Ligament (ACL) injury

Anterior cruciate ligament (ACL) rupture involves very significant changes both locally and in other structures and soft tissues (mainly due to the biomechanics of gait) that we have previously shown in case studies. In addition, there are various factors to consider, the first and most important of which is whether a surgical operation occurs, and in this case, the type of plasty used, the type of readaptation, or the potential subsequent development of osteoarthritis is also relevant that is going to affect that knee and its prognosis.

Many of these factors can be monitored to a large extent through different technologies, among which thermography has shown very interesting results in recent years (Cano-Piñonosa 2016). Monitoring with thermography helps to know the physiological state of that joint throughout the recovery process, knowing that it has a hyperthermic reaction. In addition, a “thermal scar” will accompany the process and the subsequent life of the individual. For this reason, thermography is a very interesting tool in the control of this joint.

In the following figure, we show the different statistical analyses that have been carried out and incorporated into the software.

Ankle sprain follow-up

An ankle sprain is another injury that involves connective and arthrokinematic tissue, so its response will be hyperthermic as it is related to an increase in metabolism in that region. In principle, all sprains should behave in the same way, what could vary would be the acute response to the increase in temperature, depending on the degree of the sprain and the location.

We have previously published case studies and their correlation with technologies such as GPS. In this case, we are talking about the database of 32 cases of ankle sprain, which, as in the case of ACL injuries, has hyperthermic behaviour. Another of the findings that have been seen with this type of injury is that if they are subjected to thermal stress and analyzed by means of dynamic thermography, underlying alterations can be observed, even though time has passed since the injury. Therefore, it seems that, in the same way that occurred with the ACL lesion, there is a signal or “thermal scar” that must be controlled.

The following figure reports the analysis to generate the follow-up chart for this type of lesion.

Injury follow-up muscle injuries

On muscle injuries and monitoring with thermography, there are several investigations (Fernandez-Cuevas et al. 2022; Pimenta E et al. 2022). It should be noted in your answer, that contrary to the intuitive idea, we are going to find a hypothermic region. During the first phases of the injury, we have hypothermic behaviour that harmonises with recovery. When athletes recover from this type of injury, we do not usually find signs of a “scar” as in other tissues. This may be because it is a highly vascularized and innervated tissue and therefore when it recovers it returns to thermal equilibrium.

In the following graphs, we observe the pattern in the follow-up and evolution of muscle injury.

Injury follow-up of bone fractures

Finally, bone lesions have a hyperthermic behaviour, which had already been previously described in the literature (Curkovic et al 2015; Haluzan et al. 2015). This may be due to the importance of that tissue for survival and increased metabolism to repair it. This behaviour, as in sprains, will depend on the severity and the affected structures, but it will always be hyperthermic.

As its recovery progresses, the pattern recovers its balance, since it is a deep tissue, covered in many layers and with little vascularity, when we are in the last phases of its recovery, the asymmetry should be close to degrees of symmetry. This can be seen in this case study we published on a stress fracture.

The following figure shows the evolution graphs of the different data from which we extract our monitoring graph.

Conclusions

Depending on the type of tissue injured, there are two responses: cold and hot. The hyperthermic ones are the majority (bone, ligament, meniscus, fascia) and the hypodermic ones mainly affect muscle and nerve injuries.

Our idea and commitment are to continue researching to improve both the database and the tools for the practical and intuitive use of thermography in an injury monitoring application. The data that we show here will be updated as we can collect more cases, and thus improve the reference values for the evolution of injuries.

References

Ćurković, S., Antabak, A., Halužan, D., Luetić, T., Prlić, I., & Šiško, J. (2015). Medical thermography (digital infrared thermal imaging–DITI) in paediatric forearm fractures–A pilot study. Injury, 46, S36-S39.

Fernandez-Cuevas et al. (2020). Thermal profile description of most common soccer injuries by Infrared Thermography: case studies. “ I International Congress on Application of Infrared Thermography in Sport Science” Valencia, Spain

Fernández-Cuevas et al. (2022). Hamstring injuries in professional soccer players get colder. Infrared Thermography as an additional technology for return to play decisions. Conference: 27th Annual Congress of the European College of Sport Sciences ECSS. Sevilla, Spain

Haluzan D, Davila S, Antabak A, Dobric I, Stipic J, Augustin G, Ehrenfreund T, Prlic I. Thermal changes during healing of distal radius fractures-Preliminary findings. Injury. 2015 Nov;46 Suppl 6:S103-6.

Pimenta, E. M. (2022). The Integrated Use of Thermography and Ultrasonography as Predictive Load Control Model of Muscle Injuries in Soccer Athletes. J Clin Med Img, 6(18), 1-8.

Piñonosa Cano, S. (2016). Use of infrared thermography as a tool to monitor skin temperature along the recovery process of an anterior cruciate ligament surgery (Doctoral dissertation, Ciencias).