The ‘missing piece’ sign: distant migration of a patellar tendon cerclage wire

Abstract

A 37-year-old man presented with a tender palpable lump medial to his left patella. Two years previously he underwent surgical repair of a patellar tendon rupture including a protecting cerclage wire. He was informed that the wire did not require removal. There was no further history of trauma subsequent to the surgery. He had no other musculoskeletal problems and no past history of relevance. Clinical examination revealed a midline scar over the left knee with a tender palpable wire on the medial side of the patella. There were no other significant clinical findings in the knee. Plain radiographs revealed three wire fragments around the knee (Figure 1). These three fragments did not appear to account for the full circumference of the patellar tendon, raising the concern of a missing piece of wire. A further radiographic survey revealed that the missing wire fragment lay at the anterolateral aspect of the ankle joint (Figures 2 and 3). On surgical exploration, the wire was located between the peroneus tertius and extensor digitorum longus tendons with the tip just proximal to the superior retinaculum. It was assumed to have found its way from the subcutaneous space anterior to the knee into the anterior compartment of the leg and migrated distally to abut the talus.