A connection between the fibularis longus tendon and plantar aponeurosis

Introduction Plantar fasciitis is a debilitating condition that results from pain coming from the plantar aponeurosis, which has distinct medial, central, and lateral bands. During its descent, the fibularis longus tendon passes close to the lateral and central bands of the plantar aponeurosis as it crosses the cuboid bone. As it does so it sometimes gives off accessory connections called the anterior and posterior frenular ligaments. We noted the existence of a previously-unrecognized fibrous band that also arose from the tendon of the fibularis longus and inserts into the central and lateral bands of the plantar aponeurosis. This band may be an unrecognized source of pain in plantar fasciitis and might connect dysfunction of the lateral leg muscles and the plantar aponeurosis. Methods The leg and plantar foot of 20 specimens from anatomical donors were dissected to identify any connections between the fibularis longus tendon and the plantar aponeurosis. The lateral band of the plantar aponeurosis was then reflected from its attachments, followed by the central band. Once free, connections between the plantar aponeurosis and fibularis longus tendon were cleaned and examined. Their width at the widest point was measured using Vernier digital calipers. The length of the ligament from its origin on the fibularis tendon to the plantar aponeurosis was measured in the same way. Results The fibrous band was present in 16/20 (80%) CI [0.563, 0.943] of the feet examined as a single, broad, flat ligament (14/16) with an average width of 9.4 mm [range 4.0–20.1 mm] and average length of 9.4 mm [range 5.0–11.8 mm], or as two distinct bands. Discussion This band may assist in stabilizing the arches of the foot during loading and may play a role in the biomechanics and clinical conditions related to the fibularis longus muscle and plantar aponeurosis.