Tag: Fractional curve

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Coronal balance with circumferential minimally invasive spinal deformity surgery for the treatment of degenerative scoliosis

J Neurosurg Spine 34:879–887, 2021

Coronal malalignment (CM) in adult spinal deformity is associated with poor outcomes and remains underappreciated in the literature. Recent attempts at classifying CM indicate that some coronal shifts may be more difficult to treat than others. To date, outcomes for circumferential minimally invasive surgery (cMIS) of the spine in the context of these new CM classifications are unreported.

METHODS A retrospective evaluation of patients with degenerative scoliosis (Cobb angle > 20 ) consecutively treated with cMIS at a single institution was performed. Preoperative and 1-year postoperative standing radiographs were used to make the comparisons. Clinical outcome measures were compared. Patients were subgrouped according to the preoperative distance between their C7 plumb line and central sacral vertical line (C7-CSVL) as either coronally aligned (type A, C7-CSVL < 3 cm); shifted ≥ 3 cm toward the concavity (type B); or shifted ≥ 3 cm toward the convexity (type C) of the main lumbar curve.

RESULTS Forty-two patients were included (mean age 67.7 years). Twenty-six patients (62%) were classified as type A, 5 patients (12%) as type B, and 11 patients (26%) as type C. An average of 4.9 segments were treated. No type A patients developed postoperative CM. All type B patients had CM correction. Six of the 11 type C patients had CM after surgery. Overall, there was an improvement in the C7-CSVL (from 2.4 to 1.8 cm, p = 0.04). Among subgroups, only type B patients improved (from 4.5 to 0.8 cm, p = 0.002); no difference was seen for type A patients (from 1.2 to 1.4 cm, p = 0.32) or type C patients (from 4.3 to 3.1 cm, p = 0.11). Comparing type C patients with postoperative CM versus those without postoperative CM, patients with CM had worse visual analog scale back scores at 1 year (5 vs 1, p = 0.01). Moreover, they had higher postoperative L4 tilt angles (11  vs 5 , p = 0.01), indicating inadequate correction of the lumbosacral fractional curve.

CONCLUSIONS cMIS improved coronal alignment, curve magnitudes, and clinical outcomes among patients with degenerative scoliosis. It did not result in CM in type A patients and was successful at improving the C7-CSVL in type B patients. Type C patients remain the most difficult to treat coronally, with worse visual analog scale back pain scores in those with postoperative CM. Regional coronal restoration of the lumbosacral fracture curve should be the focus of correction in cMIS for these patients.

 

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Curve Laterality for Lateral Lumbar Interbody Fusion in Adult Scoliosis Surgery: The Concave Versus Convex Controversy

Neurosurgery 83:1219–1225, 2018

Minimally invasive lateral lumbar interbody fusion (LLIF) is an effective adjunct in adult degenerative scoliosis (ADS) surgery. LLIF approaches performed fromthe concavity or convexity have inherent approach-related risks and benefits.

OBJECTIVE: To analyze LLIF approach-related complications and radiographic and clinical outcomes in patients with ADS.

METHODS: A multicenter retrospective review of a minimally invasive adult spinal deformity database was queried with a minimum of 2-yr follow-up. Patients were divided into 2 groups as determined by the side of the curve from which the LLIF was performed: concave or convex.

RESULTS: No differences between groups were noted in demographic, and preoperative or postoperative radiographic parameters (all P > .05). There were 8 total complications in the convex group (34.8%) and 21 complications in the concave group (52.5%; P = .17). A subgroup analysis was performed in 49 patients in whom L4-5 was in the primary curve and not in the fractional curve. In this subset of patients, there were 6 complications in the convex group (31.6%) compared to 19 in the concave group (63.3%; P < .05) and both groups experienced significant improvements in coronal Cobb angle, Oswestry Disability Index, and Visual Analog Scale score with no difference between groups.

CONCLUSION: Patients undergoing LLIF for ADS had no statistically significant clinical or operative complication rates regardless of a concave or convex approach to the curve. Clinical outcomes and coronal plane deformity improved regardless of approach side. However, in cases wherein L4-5 is in the primary curve, approaching the fractional curve at L4-5 from the concavity may be associated with a higher complication rate compared to a convex approach.

 

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