A Simple External Fixator Construct for Intra-operative Assessment of the Distal Femur Coronal Mechanical Alignment: A Case Report
Abstract
Stable surgical fixation of the distal femur relies significantly on accurate restoration of the lower limb mechanical axis. Methods previously described such as the cable method, axis board method, and alignment rod method require assessment to be performed with the lower limb in extension. We describe a novel technique – which utilises simple and easily accessible components such as an Ilizarov half-ring, connecting rod, and two nuts – that permits intra-operative assessment of the lower limb mechanical axis with the knee in both flexion or extension. Allowing the knee to remain in flexion also facilitates fracture reduction, as the flexed position reduces the pull of the gastrocnemius muscle on the distal fragment. Intra-operatively, the Ilizarov half-ring is attached to the connecting rod in at the perpendicular and secured with two nuts. Fluoroscopy is used to confirm that the ring is placed parallel to the knee joint, and the tip of the rod centred on the femoral head; when both of these landmarks are aligned, it indicates the lower limb mechanical axis has been restored. This technique has proven accurate and reproducible in our institution but will require further evaluation with more detailed studies in a larger patient sample.
Abstract | Reference
