Short-Segment Decompression/Fusion Versus Long-Segment for Lenke-Silva VI ADS

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Short-Segment Decompression/Fusion Versus Long-Segment Decompression/Fusion and Osteotomy for Lenke-Silva Type VI Adult Degenerative Scoliosis

Adult degenerative scoliosis (ADS), characterized by a spinal curvature exceeding 10° in skeletally mature individuals, is increasingly prevalent among aging populations. It arises from degenerative changes in intervertebral discs and facet joints, leading to deformities in the coronal, sagittal, and axial planes. Patients often experience debilitating symptoms such as lower back pain, radiculopathy, spinal stenosis, and postural imbalance. Surgical intervention becomes necessary when conservative treatments fail, particularly for severe cases classified under the Lenke-Silva system. This study focuses on Lenke-Silva type VI ADS, defined by Cobb angles >30°, spinal flexibility 50 mm, and lateral or rotational vertebral displacement. Traditionally, long-segment decompression/fusion with osteotomies has been recommended for these complex deformities. However, this approach carries risks of significant blood loss, complications, and prolonged recovery. Recent debates emphasize balancing surgical efficacy with minimizing trauma, prompting investigations into short-segment fusion as a potential alternative.

Study Design and Methodology

This retrospective analysis reviewed 28 patients (6 males, 22 females; mean age 64.5 years) treated for Lenke-Silva type VI ADS between 2012 and 2014. Patients were divided into two groups: 12 underwent long-segment fusion with osteotomy, while 16 received short-segment fusion. Inclusion criteria required confirmed ADS diagnosis with neurogenic symptoms refractory to non-surgical management. Exclusion criteria included prior spinal surgery, infections, tumors, or incomplete follow-up.

Surgical Procedures
Long-segment fusion involved posterior instrumentation extending from the upper thoracic spine (T10) to the lumbar spine (L5/S1). Osteotomies were performed to correct angular deformities, followed by canal decompression, interbody fusion, and rod placement for sagittal realignment. Short-segment fusion targeted focal pathology, typically spanning 1–2 degenerated segments. Decompression relieved neural compression, followed by limited instrumentation and fusion without osteotomies.

Pre- and postoperative radiographic parameters were analyzed using Surgimap Spine software. Coronal balance was assessed via lumbar Cobb angles, while sagittal alignment included SVA (distance from C7 plumb line to sacral posterior angle), lumbar lordosis (LL: L1–S1 angle), pelvic tilt (PT), and sacral slope (SS). Clinical outcomes were evaluated using the Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA) score, Visual Analog Scale (VAS) for pain, and Lumbar Stiffness Disability Index (LSDI).

Results

Demographics and Surgical Metrics
Both groups demonstrated similar baseline demographics. However, significant differences emerged in operative metrics. Long-segment procedures required nearly double the operative time (6.9 vs. 4.3 hours) and blood loss (1162.5 mL vs. 571.9 mL) compared to short-segment fusion. Hospital stays were also longer for the long-segment group (15.3 vs. 10.8 days). Complications in the long-segment group included two cases of wound dehiscence and cerebrospinal fluid leakage; the short-segment group had no complications.

Radiographic Outcomes
Both groups achieved coronal correction, with Cobb angles reduced from 21.8° to 2.8° (long-segment) and 18.9° to 3.4° (short-segment). Sagittal alignment improvements, however, diverged:

  • SVA: Long-segment fusion corrected SVA from 81.2 mm to 26.8 mm, outperforming short-segment fusion (81.0 mm to 47.5 mm).
  • Pelvic Parameters: Long-segment procedures restored PT from 29.3° to 14.7° and SS from 26.9° to 39.8°, whereas short-segment fusion showed no significant PT/SS improvement (PT: 27.9° to 29.1°; SS: 27.2° to 26.1°).
  • Lumbar Lordosis: Both groups enhanced LL, though long-segment fusion achieved greater correction (−28.1° to −40.8° vs. −30.5° to −38.5°).

Clinical Outcomes
Both cohorts reported comparable postoperative improvements in pain and function:

  • ODI: Scores dropped from 74.2 to 19.8 (long-segment) and 72.7 to 15.9 (short-segment).
  • VAS: Pain scores decreased from 7.0 to 2.6 (long-segment) and 7.2 to 2.7 (short-segment).
  • JOA: Scores rose similarly in both groups (8.7 to 22.1 vs. 8.9 to 22.1).

Notably, short-segment fusion preserved lumbar mobility, reflected in lower LSDI scores (1.4 vs. 3.5).

Discussion

This study challenges the conventional preference for long-segment fusion in Lenke-Silva type VI ADS. While long-segment procedures excelled in restoring sagittal alignment, short-segment fusion achieved equivalent clinical outcomes with reduced morbidity. The key findings include:

  1. Sagittal Correction vs. Clinical Relevance: Despite inferior radiographic sagittal parameters, short-segment fusion alleviated symptoms as effectively as long-segment procedures. This suggests that aggressive sagittal correction may not always correlate with patient-reported outcomes, particularly in elderly populations with compensatory mechanisms.

  2. Surgical Risk Stratification: Long-segment fusion carried higher risks of complications, extended operative time, and greater blood loss. Short-segment fusion emerged as a safer option for patients with comorbidities or reduced physiological reserve.

  3. Lumbar Mobility Preservation: The lower LSDI scores in the short-segment group highlight retained spinal flexibility, which may enhance quality of life by minimizing adjacent segment degeneration.

  4. Indications for Short-Segment Fusion: Candidates include patients with localized degeneration, adequate paraspinal muscle strength, and sagittal imbalance amendable to limited correction. Contraindications may involve progressive kyphosis or multilevel instability requiring osteotomies.

Limitations and Future Directions
The retrospective design and small sample size limit generalizability. Short-term follow-up (18 months) precludes assessment of long-term complications like proximal junctional kyphosis. Future prospective studies should evaluate bone density’s role in instrumentation failure and refine selection criteria for short-segment approaches.

Conclusion

For Lenke-Silva type VI ADS, short-segment decompression/fusion offers a viable alternative to traditional long-segment strategies. While less effective in correcting global sagittal imbalance, it matches long-segment fusion in symptom relief and functional recovery while reducing surgical trauma. This approach merits consideration in elderly or high-risk patients, emphasizing the need for individualized surgical planning.

doi.org/10.1097/CM9.0000000000000474

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