Abnormal presentation of tibialis anterior herniation

Abstract

Herniation of muscle tissue through a defect in the fascial sheath is rare; it is extremely uncommon for a patient to present in a clinic with a symptomatic muscle hernia. The usual presentation of a tibialis anterior muscle herniation is a bulge seen at the level of a fascial defect which decreases in size or disappears when the muscle contracts. We report an abnormal presentation of a tibialis anterior herniation in which the herniation swelling became more prominent on muscle contraction instead of diminishing. It is hypothesized that an increased pressure in leg compartment leads to a partially avascular and less responsive posterior portion of tibialis anterior muscle. This fixed volume of non-contracting muscle is then pushed out through the fascial defect during active muscle contraction. The herniation in this particular case was treated by enlarging the fascial defect. No recurrence was noted in a 12 months follow-up.