(2008) Posterior instrumented correction of degenerative lumbar scoliosis augmented with ALIF vs. TLIF: 3 year clinical and radiographic outcomes

2008

BACKGROUND CONTEXT

Several approaches are possible to correct Degenerative Lumbar Scoliosis (DLS). The benefits of interbody support in fostering post-op stability and promoting fusion are also well established. Whether the interbody fusion is better performed from an anterior or posterior approach has not been studied for DLS.

PURPOSE

To compare the clinical and radiographic outcomes in a series of DLS patients treated with posterior instrumented correction/fusion with additional Anterior Lumbar Interbody Fusion (ALIF) vs. Transforaminal Lumbar Interbody Fusion (TLIF) to help define the indications for anterior surgery.

STUDY DESIGN/SETTING

Prospective, nonrandomized consecutive series of patients undergoing surgery by a single surgeon.

PATIENT SAMPLE

Forty-two consecutive patients with painful DLS age 68 years (47-85 yrs) underwent posterior instrumented reduction/fusion and ALIF in 21 patients at average 4.2 levels (3-6 levels) or TLIF in 21 at average 2.7 levels (1-4 levels). The decision of ALIF vs. TLIF was surgeon preference. ALIF group curves were larger (34° vs 27°) with less lordosis (25° vs 45°) pre-op. Follow-up averaged 38 months (24-68 months).

OUTCOME MEASURES: Oswestry Disability Index (ODI), visual analog pain scores (VAS), and pain medication use were followed. Radiograph measurements included the main scoliosis curvature, T12-S1 lordosis, coronal and sagittal spinal balance, and pelvic incidence. Fusion was defined as bridging bone on imaging without implant loosening and <3mm motion on flexion-extension.

METHODS

Indications for surgery included painful stenosis, rotational listhesis, or spinal imbalance failing >6 months conservative care. Cages and rhBMP-2 were used in TLIF, and structural allograft or cages and rhBMP-2 in ALIF. Posterior arthrodesis was achieved with local autograft and allograft. The deformity in both groups was corrected by a combination of direct translation, derotation, and compression/distraction on 5.5mm titanium rods. Posterior constructs averaged 6.8 levels (4-9 levels) for both groups. Clinical and radiographic data was collected pre-op and post-op 6 weeks, 1 year, 2 years, and latest follow-up.

RESULTS

The ALIF group had 3 nonunions, 3 adjacent level fractures, 3 revisions for adjacent level degeneration, 3 infections, and one footdrop. Revision surgery was performed in 8/21. Medical complications in this group included 1 each pulmonary embolus, ileus requiring temporary colostomy, and stroke. The TLIF group had 1 each infection, nonunion, adjacent segment degeneration, transient footdrop, and additional surgery to adjust coronal balance, with 3/21 requiring revision surgery. VAS for both groups were similar: TLIF 6.7 pre-op (3-10) improved to 2.9 (1-8), and ALIF 6.5 pre-op (0-10) improved to 2.9 (1-7). Pain medication usage declined post-op for both groups. Oswestry outcomes were also similar: TLIF 46.9 (18-66) pre-op improved to 25.5 (18-36), and ALIF 52.0 (28-82) improved to 31.0 (0-64). Curve correction was similar: ALIF group curves of 34° (13-49°) pre-op correcting 70% to 10° (0-18°). TLIF group curves of 27° (14-64°) pre-op corrected 70% to 8° (0-22°). Lordosis improvement was similar for both groups.

CONCLUSION

With current deformity correction techniques, both ALIF and TLIF are effective adjuncts in DLS surgery, with similar deformity correction and fusion rates. However, the complications with posterior-only surgery for DLS appear to be significantly fewer.