Late Complications of Adult Idiopathic Scoliosis Primary Fusions to L4 and Above

Anthony Rinella, MD; Keith Bridwell, MD; Yongjung Kim, MD; Jonas Rudzki, MD; Charles Edwards, MD; Michael Roh, MD; Lawrence Lenke, MD; Annette Berra, BA

Disclosures

Spine. 2004;29(3) 

In This Article

Abstract and Introduction

Study Design: A retrospective analysis of primary cases of adult idiopathic scoliosis treated with long instrumented fusions from the thoracic spine proximally to segments that range from T11 to L4 distally.
Objective: To analyze whether patients requiring revision surgery had lower postoperative SRS-24 scores; age ≥40 years correlated with higher rates of revision surgery; disc degeneration below the fusion occurred more commonly with a more distal lowest instrumented vertebra or older patient age (≥40 years); and whether smokers had higher rates of major complications or revision surgery.
Summary of Background Data: Few reports describe complications related to primary long fusions using modern 2+ rods, hook/pedicle screw instrumentation methods in the treatment of adult idiopathic scoliosis.
Methods: Sixty-seven patients were analyzed with an average age of 38.8 years (range 21-61 years). The average clinical follow-up was 7.8 years (range 2-16 years): 42 patients had >5 years follow-up, including 23 patients with >10 years follow-up. Patients were categorized by age (< or ≥40 years) and level of the lowest instrumented vertebra (T11-L2 vs. L3-L4). Upright radiographs and postoperative SRS-24 questionnaires from the latest follow-up date were analyzed.
Results: Patients requiring revision surgery had lower total score (average 72.0) than those that did not (total score = 94.2; P = 0.01). More specifically, patients with pseudarthrosis had lower total scores (average 74.7) than those without (average total score = 93.5; P = 0.02). When analyzing age, there were similar rates of pseudarthrosis, but higher rates of transition syndrome (2) and sagittal/coronal imbalance (1 each) in patients ≥40 years. Subsequent distal disc degeneration did not correlate significantly with more distal lowest instrumented vertebra or older patient age. Smokers did not have higher rates of major complications or revision surgery than nonsmokers.
Conclusions: Patients with adult idiopathic scoliosis and long fusions had similar pseudarthrosis rates, but higher rates of transition syndrome when lowest instrumented vertebra was L3-L4 relative to levels T11-L2. When categorized by age, complication rates were similar in each group. Patients with pseudarthroses or other diagnoses requiring revision surgery had lower SRS-24 total scores than those without (P = 0.02 and P = 0.01, respectively).

The decision of fusion levels in the surgical treatment of adult idiopathic scoliosis (AIS) is often complex and based on a number of factors: sagittal and coronal balance, the degree and pattern of degenerative changes or neurologic compromise, as well as the patient's overall health, symptoms, and expectations. Several studies have delineated patient outcomes-often in the form of pain or functional assessments[1,2,3] -and complication rates. These studies are frequently based on experience with Harrington instrumentation[4,5,6,7] or mix various diagnoses[8] or treatment type[9] (primary vs. revision, etc.). There is some evidence that long fusions to more distal lumbar levels increases the likelihood of complications, especially with fusions to L5 or S1.[10,11,12] All of these factors make extrapolation of conclusions to more modern 2+ rod-segmental hook/screw constructs difficult.

In order to study a relatively homogenous group, we chose to assess patients with adult scoliosis after primary instrumented fusions from the thoracic spine proximally to segments ranging from T11 proximally to L4 distally. The following hypotheses were made and tested:

  1. Patients with pseudarthrosis or other diagnoses requiring revision surgery will have lower postoperative SRS-24 scores in all domains relative to patients not requiring revision surgery.

  2. Major long-term complications requiring revision surgery will be more likely in older patients (≥40 years) than younger patients.

  3. Subsequent disc degeneration below the fusion will:

    1. Have a higher incidence in patients with more distal lowest instrumented vertebra (LIV);

    2. Be more likely in older patients (≥40 years).

  4. Smokers will have a higher rate of major complications and revision surgery than nonsmokers.

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