Plantar fasciitis vs Baxter’s neuropathy: a case study of diagnosis support with thermography in podiatry

02/05/2021 By: Ismael Fernández Cuevas Home

A case study where thermography can guide the decisions making in podiatry. Not all plantar heel pain are a plantar fasciitis and how to deal with Baxter’s neuropathy

Plantar heel pain is a very common symptom among high performance and amateur athletes (but not only). We normally relate this pain to plantar fasciitis, which is, in most of the cases, a correct diagnosis. In this case study, we will show how thermography helped to reconsider a plantar fasciitis case based on the thermal results (remember “hot or cold“, that is the key factor)

This is the case study of a female athlete (25 years old), specialized in 800m, that was diagnosed at the end of 2020 with plantar fasciitis in her right foot. The symptoms were compatible with the diagnosis (plantar heel pain, more intense in the early morning or after resting, etc.). Physiotherapy treatment, shockwave therapy and cortisone shots were applied during weeks. In addition to that, she also got insoles. Sadly, all these interventions did not improve the situation and she was not able to return to train because her plantar heel pain did not disappear.

“…12.1% of all musculoskeletal foot and ankle consultations in primary care in 2006 were related to heel pain, with 7.5% of them specifying plantar fasciitis. That means that not all plantar heel pain are a plantar fasciitis…”
Menz and collaborators (2010)

The first thermography evaluation was performed on the 10th March 2021, more than 2 months after the diagnosis. At that stage, the athlete did not refer pain -she could do some strength and swimming training-, but heel contact or running were painful activities (5/10 in a NRS pain scale): she was not able to run in the previous 8 weeks.

When taking the foot sole thermal image, we asked her to point at the painful region (figure 1). There was something that did not make sense.

**Figure 1**. Thermal image of the athlete pointing at the painful region diagnosed with plantar fasciitis

One of the most interesting applications of infrared thermography is diagnosis support. This is possible because, depending on the injury/pathology and the involved tissue, the thermal response might be different (Sillero-Quintana et al., 2015). In this case, plantar fasciitis is pathology linked to a hyperthermic response (Gómez Bernal et al., 2020). Thus, we expected to find a warmer right heel and we found a colder one (you can see figure 2, representing the thermal image and asymmetries analyzed by ThermoHuman with -1.92ºC colder right inner arch).

**Figure 2**. Thermal image (on the left) and ThermoHuman thermal asymmetry representation (on the right) of the foot sole of the first athlete evaluation. Please note that the purple line indicates pain and the stripped pattern indicates injury.

In a study performed in the UK (Menz et al., 2010), the authors reported that 12.1% of all musculoskeletal foot and ankle consultations in primary care in 2006 were related to heel pain, with 7.5% of them specifying plantar fasciitis. That means that not all plantar heel pain are a plantar fasciitis. Indeed, Buchbinder (2004) showed some differential diagnosis of plantar heel pain (figure 3), among them we find several nerve issues.

These thermal results forced us to recommend the reconsideration of the diagnosis. Bearing in mind the shown hypothermic pattern (characteristic from nervous issues), we suggest to explore potential differential diagnosis related to nerve syndromes (as the known as Baxter’s neuropathy or Inferior Calcaneal Nerve compression)

**Figure 3**. Adapted list from Buchbinder (2004) (found in Thomas et al., 2019)

Two weeks after the first evaluation, we repeat the assessment on the athlete (24th March 2021). Before that and as a result of the conclusions from the first assessment, she visited an expert that was carefully assessing her case: he found out that her right ankle was blocked. Therefore he started a different treatment focused on releasing the pressure on inner foot and mobilizing the ankle joint. As a result, she started running again pain free (she only reported a mild tingling sensation, which may in fact be an indicator that the nerve has been affected).

“…We can conclude that infrared thermography is a valid tool to support heel pain diagnosis […] in this case study, what was considered as a plantar fasciitis (hyperthermic pattern) did not agree with what was shown on the thermal evaluation: an hypothermic pattern (more linked to nerve issues as Baxter’s neuropathy), which helped reconsidering the diagnosis and treatment and therefore, the athlete could return to running and training without pain…”
Ismael Fernández Cuevas

By the second thermal evaluation, we observed that the injured and painful area (the right foot medial longitudinal arch) presented a no significant -0.12ºC asymmetry. That means a thermal asymmetry decrease of 1.80ºC from the first to the second evaluation (14 days). This evolution can be seen on figure 4.

**Figure 4**. Thermal images, ThermoHuman asymmetry avatars and chart representing the absolute asymmetry evolution of the foot medial longitudinal arch from the first evaluation to the second one 14 days after.

We can conclude that infrared thermography is a valid tool to support heel pain diagnosis, which can be especially interesting for professionals from the world of podiatry, physiotherapy and sports medicine, given the frequency of this injury. In this case study, what was considered as a plantar fasciitis (hyperthermic pattern) did not agree with what was shown on the thermal evaluation: an hypothermic pattern (more linked to nerve issues as Baxter’s neuropathy). After reconsidering the diagnosis and treatment, thermography was also helpful to confirm the significant reduction of the thermal asymmetry in the injured and painful area (from -1.92ºC to -0.12ºC) in just 14 days. During this period, the athlete could return to normal training with no pain. ThermoHuman software was useful to process, quantify and illustrate these results.

REFERENCES

Buchbinder, R. (2004). Plantar Fasciitis. New England Journal of Medicine, 350(21), 2159-2166. doi: 10.1056/NEJMcp032745

Gómez Bernal, A., Fernández-Cuevas, I., Alfaro-Santafé, J. J., & Pérez-Morcillo, A. (2020). Termografía infrarroja para la determinación del perfil térmico en fascitis plantar: estudio descriptivo. Revista Espaсola de Podologнa, 31(Supl1), 1.

Menz, H. B., Jordan, K. P., Roddy, E., & Croft, P. R. (2010). Characteristics of primary care consultations for musculoskeletal foot and ankle problems in the UK. Rheumatology (Oxford, England), 49(7), 1391-1398. doi: 10.1093/rheumatology/keq092

Sillero-Quintana, M., Fernández-Jaén, T., Fernández-Cuevas, I., Gómez-Carmona, P. M., Arnaiz-Lastras, J., Pérez, M.-D., & Guillén, P. (2015). Infrared Thermography as a Support Tool for Screening and Early Diagnosis in Emergencies. Journal of Medical Imaging and Health Informatics, 5(6), 1223-1228. doi: 10.1166/jmihi.2015.1511

Thomas, M. J., Whittle, R., Menz, H. B., Rathod-Mistry, T., Marshall, M., & Roddy, E. (2019). Plantar heel pain in middle-aged and older adults: population prevalence, associations with health status and lifestyle factors, and frequency of healthcare use. BMC musculoskeletal disorders, 20(1), 337-337. doi: 10.1186/s12891-019-2718-6