Tag: Spinal canal stenosis

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Radiographic and MRI evidence of indirect neural decompression after the anterior column realignment procedure for adult spinal deformity

J Neurosurg Spine 37:703–712, 2022

The anterior column realignment (ACR) procedure, which consists of sectioning the anterior longitudinal ligament/annulus and placing a hyperlordotic interbody cage, has emerged as a minimally invasive surgery (MIS) for achieving aggressive segmental lordosis enhancement to address adult spinal deformity (ASD). Although accumulated evidence has revealed indirect neural decompression after lateral lumbar interbody fusion (LLIF), whether ACR serves equally well for neural decompression remains to be proven. The current study intended to clarify this ambiguous issue.

METHODS A series of 36 ASD patients with spinopelvic mismatch, defined as pelvic incidence (PI) minus lumbar lordosis (LL) > 10°, underwent a combination of ACR, LLIF, and percutaneous pedicle screw (PPS) fixation. This “MIS triad” procedure was applied over short segments with mean fusion length of 3.3 levels, and most patients underwent single-level ACR. The authors analyzed full-length standing radiographs, CT and MRI scans, and Oswestry Disability Index (ODI) scores in patients with minimum 1 year of follow-up (mean [range] 20.3 [12–39] months).

RESULTS Compared with the preoperative values, the radiographic and MRI measurements of the latest postoperative studies changed as follows. Segmental disc angle more than quadrupled at the ACR level and LL nearly doubled. MRI examinations at the ACR level revealed a significant (p < 0.0001) increase in the area of the dural sac that was accompanied by significant (p < 0.0001) decreases in area and thickness of the ligamentum flavum and in thickness of the disc bulge. The corresponding CT scans demonstrated significant (all p < 0.0001) increases in disc height to 280% of the preoperative value at the anterior edge, 224% at the middle edge, and 209% at the posterior edge, as well as in pedicleto-pedicle distance to 122%. Mean ODI significantly (p < 0.0001) decreased from 46.3 to 26.0.

CONCLUSIONS The CT-based data showing vertebral column lengthening across the entire ACR segment with an increasingly greater degree anteriorly suggest that the corrective action of ACR relies on a lever mechanism, with the intact facet joints acting as the fulcrum. Whole-segment spine lengthening at the ACR level reduced the disc bulge anteriorly and the ligamentum flavum posteriorly, with eventual enlargement of the dural sac. ACR plays an important role in not only LL restoration but also stenotic spinal canal enlargement for ASD surgery.

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Poor Fusion Rates Following Cervical Corpectomy Reconstructed With an Expandable Cage

Neurosurgery 89:617–625, 2021

Expandable cages are often used to reconstruct cervical corpectomies but there are few long-term follow-up studies with large numbers.

OBJECTIVE: To analyze the clinical and radiographic results of cervical corpectomy reconstructed with expandable cages for degenerative stenosis.

METHODS: We performed a retrospective analysis of 78 patients with degenerative cervical stenosis treated with a corpectomy reconstructed with an expandable cage. We evaluated the clinical and radiographic outcomes, as well as complications of the procedure at a minimum 2-yr follow-up.

RESULTS: There was a decrease in the visual analog scale pain average from 75 mm to 8.5mm(P=.02); a decrease in the Neck Disability Index average from55% to 12% (P=.009); and improvement in the Japanese Orthopaedic Association average from 12 to 14 points (P = .01). There was a change in cervical lordosis (Cobb method) average from −9.3◦ to −15.1◦ (P = .002), without significant loss of lordosis (P = .63). The fusion rate, by criteria of theCervical Spine Research Society (CSRS), was low: using dynamic X-rays –50%(n=39/78) and using computed tomography (CT) – 47.4% (n = 37/78). A total of 11 patients (14.1%) suffered complications.

CONCLUSION: To our knowledge, this is the largest series (78)with a minimum 2-yr followup in the literature and the first using the dynamic radiographic and CT criteria endorsed by the CSRS. Using these criteria, our fusion rates were much lower than all previous reports in the literature. Despite this, patient-reported outcomes were reasonable. There was a relatively low incidence of perioperative complications, most of which were likely not implant-specific and there was only 1 case of implant failure.

 

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