Harrington rod is a surgical implant used to stretch the spine in order to correct abnormal curvature. The rod is attached to the spine with hooks inserted into the vertebra at the top of the curve and the vertebra at the bottom of the curve.
The Harrington rod has a ratcheting mechanism that works to straighten the spinal curve and stabilize the spine. The vertebrae in between the hooks are then allowed to fuse.
The Harrington rod is largely an antiquated spinal fixation system as it only allowed fixation at two points. Modern rod fixation systems used for deformity surgery allow for multiple points of fixation making it much stronger. The newer systems also allow for better correction of deformity.