Increased flexor hallucis longus tension decreases ankle dorsiflexion

Abstract

BackgroundRestricted excursion of the flexor hallucis longus (FHL) is associated with several clinical problems. An FHL excursion measurement device (EMD) was used to objectively assess differences between patients with clinically normal or tight FHL tendons. Methods188 patients (356 feet) were enrolled. The EMD measured maximum ankle dorsiflexion with the great toe in 15°, 30°, and 45° of dorsiflexion. All had clinical assessment of FHL tightness by their provider independently of the EMD measurement. ResultsIncreased hallux DF always caused decreased ankle DF. Patients with clinically tight FHLs demonstrated decreased ankle DF compared to normal subjects at all hallux positions (p<0.01). The EMD measurement was not sensitive enough for detection of FHL tightness in individuals. A clinically tight FHL was seen in almost 50% of feet. ConclusionsTension in the FHL can limit ankle DF. Clinical tightness of the FHL is likely more common than currently recognized.