Three patients developed lumbar radicular pain after Harrington instrumentation and posterior spinal fusion for idiopathic scoliosis. They required a second surgical procedure for nerve root decompression. The presenting complaint after the initial procedure was persistent radicular and buttock pain. Subsequent evaluation revealed direct compression by the inferior hook. At surgery the inferior hook was noted to be encased in bone and had imploded into the canal after a stress fracture of the lamina. Removal of the entire Harrington instrumentation resulted in effective relief of nerve root compression and resolution of radicular pain. To avoid this occurrence the addition of a leg extension to a postoperative brace has been instituted for procedures involving instrumentation to L5 and occasionally to L4.