Abundant synovium surrounding posterior tibial tendon. This extended from inferior edge of flexor retinaculum to tuberosity of navicular. Evaluation for rheumatoid arthritis and seronegative spondyloarthropathy was negative. Patient was large-framed man who had mild unilateral pes planus and posterior tibial insufficiency secondary to tenosynovitis and loss of tendon excursion through pulley of flexor retinaculum (laciniate ligament). SEE TECHNIQUE 83.1.