Plantar fasciitis and calcaneal spur formation are associated with abductor digiti minimi atrophy on MRI of the foot

Objective To determine the association of atrophy of the abductor digiti minimi muscle (ADMA), an MRI manifestation of chronic compression of the inferior calcaneal nerve suggesting the clinical diagnosis of Baxter’s neuropathy, with MRI markers of potential etiologies, including calcaneal spur formation, plantar fasciitis, calcaneal edema, Achilles tendinosis and posterior tibial tendon dysfunction (PTTD). Materials and methods Prevalence of calcaneal spur formation, plantar fasciitis, calcaneal edema, Achilles tendinosis and PTTD was assessed retrospectively on 100 MRI studies with ADMA and 100 MRI studies without ADMA. Patients ranged in age from 10–92 years. Pearson chi-square analyses and Fisher’s exact test were used to compare prevalence of the above findings in patients with and without ADMA. Logistic regression was used to determine which variables were significantly associated with ADMA. Results Among patients with ADMA, there was significantly greater age (57.2 years vs 40.8 years, p \u3c 0.001), presence of Achilles tendinosis (22.0% vs 3.0%, P \u3c 0.001), calcaneal edema (15.0% vs 3.0%, P = 0.005), calcaneal spur (48.0% vs 7.0%, P \u3c 0.001), plantar fasciitis (52.5% vs 11.0%, P \u3c 0.001), and PTTD (32.0% vs 11.0%, P \u3c 0.001). After multivariate logistic regression analysis, only age [odds ratio (OR) 1.06, 95% confidence interval (CI) 1.03, 1.09], calcaneal spur (OR 3.60, 95% CI 1.28, 10.17), and plantar fasciitis (OR 3.35, 95% CI 1.31, 8.56) remained significant. Conclusion Advancing age, calcaneal spur, and plantar fasciitis are significantly associated with ADMA. Their high odds ratios support the notion of a possible etiologic role for calcaneal spur and plantar fasciitis in the progression to Baxter’s neuropathy

Biomechanical evaluation of two clinical tests for plantar heel pain: The dorsiflexion-eversion test for tarsal tunnel syndrome and the windlass test for plantar fasciitis

Background: Plantar heel pain may result from several conditions such as tarsal tunnel syndrome (TTS) and plantar fasciitis. The dorsiflexion-eversion test is used to diagnose TTS, whereas the windlass test is used for plantar fasciitis. Given the similarity between both tests, the purpose of this study was to evaluate whether these tests are able to selectively load the structures which they aim to examine. Methods: Both tests were evaluated in six cadavers by measuring strain in the plantar fascia, tibial nerve, lateral plantar nerve (LPN), and medial plantar nerve (MPN) using miniature displacement transducers. Longitudinal excursion of the nerves was measured with a digital caliper. Results: With the dorsiflexion-eversion test, dorsiflexion and eversion of the ankle in combination with extension of the metatarsophalangeal (NITP) joints significantly increased strain in the tibial nerve (+1.1%), LPN (+2.2%), and MPN (+3.3%) but also in the plantar fascia (+1.2%) (all: p = 0.016). Both components (dorsiflexion-eversion and MTP extension) resulted in significant increases. With the windlass test, extension of all MTP joints significantly increased strain in the plantar fascia (+0.4%, p = 0.016), but also in the tibial nerve (+0.4%, p = 0.016), LPN (+0.8%, p = 0.032) and MPN (+2.0%, p = 0.016). Excursion of the nerves was always in the distal direction but only reached significance for the tibial nerve (6.9 mm, p = 0.016) and LPN (2.2 mm, p = 0.032) during the dorsiflexion-eversion test. Conclusions: Both tests mechanically challenge various structures that have been associated with plantar heel pain. This questions the usefulness of the tests in the differential diagnosis of plantar heel pain