Blood flow in the human Achilles tendon assessed by laser Doppler flowmetry

This study evaluated microvascular perfusion in the human Achilles tendon by laser Doppler flowmetry (LDF) at rest, during vascular occlusion, and during passive stretch and isometric contraction of the triceps surae. In 40 healthy volunteers, an intratendinous needle probe was introduced 5 mm above the distal insertion, at the midportion, and at the musculotendinous junction of both legs. Values were obtained at rest and during temporary vascular occlusion. Twenty-eight of the subjects also were assessed during physical provocation by passive stretch and isometric contraction of the triceps surae. Blood flow was significantly lower near the calcaneal insertion but otherwise was distributed evenly in the tendon. The output signal showed a pulsatile variation synchronous with heart activity, and temporary vascular occlusion always caused a pronounced reduction in LDF values. Passive stretch and isometric contraction induced a progressive decline in LDF values as tension increased. Hyperemia often appeared after contraction. Tendon blood flow was higher in women and decreased with increasing age.