Four Thousand Wires Under the Lamina

Background Context: Sub laminar wiring (SLW) has been labeled as a neurologically hazardous technique of spinal fixation based on few repeatedly cited reports, most of which are over two decades old. There are few modern reports about the safety of SLW. Purpose: To evaluate the neurological safety of SLW. Study Design: This clinical study is a retrospective analysis of 273 consecutive patients in whom 4275 sub laminar wires were used for spinal fixation for varying etiologies. Outcome Measures: Frankel grading was used to quantify pre and post operative neurological status.

Methods: An independent observer analyzed 273 successive patients operated using SLW between May 1993 to June 2004 at our clinic. Follow up period ranged from 2 to 12 years. These consisted of 90 deformities, 45 tumors, 38 fractures and 100 infections. Pre and postoperative neurological status (using Frankel's grading) was documented in each patient. Indications for SLW, levels and number of wires used in each case were also noted.

Results: 175 of the 273 patients had some neurological deficit at the time of surgery (Frankel A = 39, Frankel C = 111). 143 of the 175 patients with pre operative neurological deficit showed neurological recovery post operatively, of which 107 had a recovery of over 2 Frankel grades. Fifteen patients with a pre op Frankel A (total sensori motor deficit) regained functional power (grade C or more) post operatively. 31 of the 175 patients remained unchanged neurologically post op. 1 patient developed an implant related cord deficit post operatively, unreleated to he wiring. No patient had any major wire related neurological complications. Two patients developed transient radicular paraesthesiae post op, which recovered.

Conclusions: Sublaminar wiring is a safe technique, if done using the correct principles and techniques, in the correct indications.