Coxa pedis: can calcaneal pronation angle be considered a predictive sign of medial plantar arch overload?

Abstract

PurposeTo assess whether a correlation between the calcaneal pronation angle and the presence of internal plantar arch overload signs (such as upper-medial spring ligament lesion, posterior tibial tendon tenosynovitis, etc.) could lead to a better understanding of coxa pedis pathology.Material and methodsOne hundred ankle MRIs of consecutive patients were retrospectively reviewed measuring the calcaneal pronation angle and either the presence or absence of internal plantar arch overload signs. Next, the association of overload signs with increasing pronation angle was evaluated to establish a cut-off point beyond which coxa pedis pathology could be defined.ResultsThe tibial-calcaneal angle values in patients with and without effusion proved to be significantly different (p < 0.0001). The tibial-calcaneal angle values in patients with and without oedema also demonstrated a significant difference (p < 0.0056). Regarding posterior tibial tendon, a significant difference was found between the two groups (p < 0.0001). For plantar fascia enthesopathy, the result was borderline significant (p < 0.054). A linear correlation was found between the value of pronation angle and the extent of spring ligament injury (p < 0.0001). In contrast, no correlation with age was found.ConclusionIn conclusion, the literature associates medial longitudinal plantar arch overload with posterior tibial tendinopathy and spring ligament complex injuries. Our data show that both injuries are highly correlated with increased calcaneal pronation angle, which could be considered a predictive sign of internal plantar arch overload, prior to the development of the associated signs.