Are enlarged peroneal tubercle and accessory anterolateral talar facet associated with calcaneal spur?

EPT may lead to the degeneration and damage of peroneal tendons and the appearance of stenosing peroneal tenosynovitis. It is an important disease in tendon disorders because EPT causes lateral foot pain, clicking sensation, discomfort when wearing shoes, and limitation of gait [12‐15]. EP itself is reported to be found in 90% of people [16, 17], and EPT is found in 20–44% [18, 19]. The rate of presence reported in this study was 31.6%, which was within the range previously reported, and the prevalence was about 30% for those over 40 years old by age group. Taneja et al. [13] and Shibata et al. [20] reported that EPT was slightly more in men and is increasingly found in middle-aged or older age groups than in younger people, but our study found less data on young people and women, which could not be concluded.

AALTF is a congenital variance, which forms a facet between the anterolateral talocalcaneal joint, the average facet size is 7 mm, that causes impingement between talus and calcaneus, resulting in pain in the lateral part of the ankle joint [4, 21, 22]. It was reported that the prevalence of AALTF was 3.6–32.7% [23, 24], and there was a report that it was also seen in 34% of children [5]. The rate of presence on AALTF in our study was 24.7%, which was within the range previously reported, and the prevalence might be about 20% for those over 40 years old by age group. Although the high prevalence has been reported in men [5, 8], it could not be concluded because there is little data available on women in the present study.

Here, we would also like to consider the pathogenesis of EPT and AALTF a little. First of all, because CS is thought to be caused by aging, obesity, physical activity, hard labor, leg deformity, the presence of arthritis [11, 25, 26], people with CS (+) might have had a lot of mechanical loads to the plantar region. From the results of our study that CS was significantly seen in the EPT (+) group, it is inferred that there is a more mechanical load on the sole of the people with EPT than in those of AALTF. We guess that tightness occurs in the peroneal tendons in people with EPT by aging, and mechanical stimulation or load is gradually added to the peroneal tubercle and made the larger size of EPT, and then, clinical symptoms such as pain and discomfort might appear. There have been some reports of flat foot accompanied with AALTF [4, 22, 27], however, because the present study showed that there was no significant relationship between CS that is deeply related to flat foot and AALTF, it was speculated that AALTF might not have occurred due to talocalcaneal impinge by flat foot. Therefore, both EPT and AALTF are congenital variants, however, EPT might be more susceptible to various acquired influences by the mechanical loads or mechanical stimulations to the plantar region than AALTF.

The limitations of this study were as follow: (1) Clinical information such as body weight, occupation, and foot pain was not obtained at all except for age and sex, (2) Gender differences could not be examined because there were few female samples, (3) We set the CS cutoff value to 3 mm, but this value is controversial, (4) The cartilage lesion could not be evaluated for observation of dried bone in the present study, and (5) The number of samples might still not be enough to obtain the prevalence of EPT and AALTF. As the above described, there are many limitations because of the research with cadaveric bones, but we would like to conduct further research in a clinical setting based on the results obtained in this study.