"Asymmetric scalloping of the regenerate": a radiological sign of pseudoaneurysm in distraction osteogenesis

Abstract

Pseudoaneurysm formation is an uncommon but well-recognised and important complication in limb reconstruction surgery. Postoperative diagnosis is usually clinical or an incidental finding. We present an 11-year-old girl, who underwent two-stage limb lengthening with a circular fixator, for a previously treated pseudoarthrosis of the tibia. During the lengthening plan, a concave defect was noted on one side of the regenerate, which was found to be due to extrinsic compression by a pseudoaneurysm. Normal regenerate formation was seen after selective embolisation of the pseudoaneurysm. This concave appearance on one side of the regenerate has previously been described secondary to a difference in stability on the two sides of the osteotomy, when a monolateral fixator is used, but not due to extrinsic compression by a pseudoaneurysm. The authors propose that this radiographic appearance of "asymmetrical scalloping" on one side of the regenerate may represent a radiological sign of a pseudoaneurysm formation and should provoke investigation for the same.

Fig. 1

a Anteroposterior and b lateral radiographs of the proximal tibia 4 months into distraction osteogenesis showing “asymmetric scalloping” of the posterolateral aspect of the regenerate

Fig. 2

Ultrasound scan around the pin sites revealing a large mass with turbulent flow, suspicious of a pseudoaneurysm

Fig. 3

a Anteroposterior and b lateral radiograph of the tibia 1-month after angiographic coil embolisation of the pseudoaneurysm arising from the anterior tibial artery. A reduction in the concavity of the regenerate was noted. The embolisation coil can be seen at the site of the pseudoaneurysm

Fig. 4

Plain radiographs at 1-year follow-up showing a fully healed corticotomy site with filling-in of the previous scalloping