[One-segment interbody lumbar arthrodesis using impacted cages: posterior unilateral approach versus posterior bilateral approach].
OBJECTIVE
We assessed the relative advantages of unilateral versus bilateral posterior approaches for lumbar spine fusion.


METHODS
Eighty-three patients who underwent lumbar spine fusion via a bilateral posterior approach and who had reached more than two years follow-up were compared with 80 patients who had undergone the same procedure via a unilateral posterior approach, including 54 with a follow-up greater than one year and 24 greater than two years. Most cases were L4-L5 fusions for degenerative spondylolisthesis or recurrent discal herniation with instability. Two composite carbon cages were filled with autologous cancellous bone. The key to the unilateral approach was the comfortable exposure of the disc by lamino-arthectomy; the osteosynthesis could then be performed unilaterally if only one gutter was opened. We measured bleeding and operative time to quantify surgical difficulty. At one year we assessed disc height, lordosis, frontal balance, and fusion of the operated disk. At two years, we assessed lombalgia and sciatalgia [scored from 4 (none) to 0 (intolerable)], subjective outcome, and recovery of former activity level.


RESULTS
Mean blood loss and operative time were 360 ml and 162 min for the 83 classical procedures and 216 ml and 118 min for the 80 unilateral procedures. There were ten dural wounds with the bilateral approach and one dural wound and one transient radicular deficit with the unilateral approach. At one year, 81 of the 83 unilateral cases had reached fusion (2 nonunions). There was a mean 2 degrees gain in discal lordosis despite three cases of impaction due to osteoporosis. For the unilateral procedures, all 54 reached fusion at one year with a mean 2.5 degrees gain in lordosis, also with 3 impactions. With intersomatic distraction, balanced disc height in the frontal plane was obtained in all cases where the initial narrowing was not excessive. There were no cases of posterior displacement. There was a degradation of the supra-adjacent segment in three of the bilateral cases and one of the unilateral cases. At two years, the mean pain score for the bilateral cases was 3.88 for lombalgia (1.22 preoperatively) and 3.51 for sciatalgia (1.30 preoperatively). For the unilateral cases, lombalgia improved from 1.57 to 3.62 and sciatalgia from 0.98 to 3.79. the difference between the two approaches was significant for sciatalgia (p<0.01). The subjective assessment for the bilateral cases was: good 34, improved 43, unchanged 4, worse 2. For the unilateral cases it was: good 10, improved 11, unchanged 2, worse 1. Thirty of the 54 active patients in the bilateral group returned to their former work at a mean 8.5 months and 11 of the 17 active patients in the unilateral group did so at a mean 7.5 months.


CONCLUSIONS
The unilateral approach simplifies the spinal fusion procedure. Fusion conditions and delay to consolidation as well as the final outcome appear to be better for sciatalgia.


CONCLUSIONS
Adapted instrumentation (cages and instruments) allow using this simplified technique for many patients with an indication for classical bilateral access fusion.
Commarmond
J
J
Clinique Saint-François, 22, rue Marcel-Lemoine, 36000 Châteauroux.
D016063:Blood Loss, Surgical / Q000706:statistics & numerical data; D004867:Equipment Design; D005500:Follow-Up Studies; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D017116:Low Back Pain / Q000175:diagnosis / Q000209:etiology; D008159:Lumbar Vertebrae / Q000601:surgery*; D008875:Middle Aged; D011859:Radiography; D020127:Recovery of Function; D012008:Recurrence; D012086:Reoperation / Q000706:statistics & numerical data; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods* / Q000523:psychology; D013168:Spondylolisthesis / Q000150:complications / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome