A semi-quantitative technique to assess excursion of the flexor hallucis longus

Background: Recent research indicates that restriction in excursion of flexor hallucis longus (FHL) contributes to hallux rigidus development. As described in the literature, clinical evaluation of FHL excursion has poor interobserver reliability. A simple, inexpensive, easily used FHL relative excursion measurement device was developed and tested. Methods: 64 subjects were enrolled with shoe size, height, weight, BMI, and age compared. Using a footplate and series of mechanical wedges, maximum ankle dorsiflexion was measured with the great toe in 15°, 30°, and 45° of dorsiflexion. Results: Ankle dorsiflexion decrease with progressive hallux dorsiflexion increase was statistically significant with a linear correlation (r² = .814 p < .001) and was not statistically related to shoe size, height, weight, BMI, or age. Conclusions: This technique provides consistent assessment of the limitation to ankle dorsiflexion incurred by decreased FHL excursion, establishing groundwork for future studies to assess the relationship between diminished FHL excursion and FHL pathology.