Distraction Laminoplasty With Interlaminar Lumbar Instrumented Fusion (ILIF) for Lumbar Stenosis With or Without Grade 1 Spondylolisthesis: Technique and 2-Year Outcomes.

STUDY DESIGN: Prospective, nonrandomized cohort.

OBJECTIVE: Describe the surgical technique and clinical outcome of distraction lumbar laminoplasty with allograft bone block augmentation and interlaminar lumbar instrumented fusion (ILIF) SUMMARY OF BACKGROUND DATA.: ILIF is a recently described technique that may offer a less invasive alternative to traditional posterior pedicle screw fixation for stabilization during posterior or posterolateral lumbar fusion after decompression for lumbar spinal stenosis.

METHODS: Data from two sites of a prospective, multicenter clinical study is described in this report and includes 37 patients over age 40 with single-level degenerative disc disease between L1-2 and L4-5 with neurogenic claudication. Subjects were treated with lumbar decompression using a distraction laminoplasty procedure followed by insertion of a preshaped allograft bone block and interspinous stabilization with a fixation device. BMP-2 was not used. Follow-up clinical evaluation was performed at baseline and at 6 weeks, 3, 6, 12, and 24 months, including perioperative complications, visual analog pain score, Oswestry Disability Index, Zurich Claudication Questionnaire scores and return to activity and work. Radiographic evaluation of fusion and segmental and regional lumbar lordosis were performed to 2 years.

RESULTS: Thirty-three patients (89%) of mean age 71 years (17% woman) met all follow-up criteria at 2 years. Levels treated were L4-5 (78.4%), L3-4 (16.2%), or L2-3 (5.4%). Thirty-two of 37 (86%) of patients had a grade-1 spondylolisthesis. Mean hospital length of stay (LOS) was 2 days. Complications included one dural tear, one new neuro deficit that resolved by 6 weeks, one implant failure, one seroma, and one case of cancer diagnosis. At 2 years, 67% had >2 cm improvement on visual analog pain score and 73% had >12.4% Oswestry Disability Index improvement. Symptom severity and physical function subset scores of Zurich Claudication Questionnaire improved by >0.5 cm in 76 and 73% of patients, respectively. At 2 years 94% of patients were off all narcotics and NSAIDS and 94% reported satisfaction with the procedure. Mean lumbar lordosis at baseline and 2 years was 53 ± 14° and 53 ± 13°, respectively. Seventy-two percent of subjects met strict fusion criterion of <3° motion on flexion/extension XRAY and bridging bone; 97% met criteria for stability by independent surgeon evaluation.

CONCLUSION: Distraction laminoplasty with allograft bone block augmentation and ILIF may provide a less-invasive alternative to traditional pedicle screw fixation after decompression and posterolateral fusion. The present study describes this technique, and demonstrates excellent clinical outcomes and an acceptable rate of radiographic fusion success.

LEVEL OF EVIDENCE: NA.