Clin Orthop Surg.  2015 Mar;7(1):77-84. 10.4055/cios.2015.7.1.77.

The Importance of Proximal Fusion Level Selection for Outcomes of Multi-Level Lumbar Posterolateral Fusion

• Nam WD
• Cho JH

• KMID: 2069878
• DOI: http://doi.org/10.4055/cios.2015.7.1.77

Abstract

BACKGROUND
There are few studies about risk factors for poor outcomes from multi-level lumbar posterolateral fusion limited to three or four level lumbar posterolateral fusions. The purpose of this study was to analyze the outcomes of multi-level lumbar posterolateral fusion and to search for possible risk factors for poor surgical outcomes.
METHODS
We retrospectively analyzed 37 consecutive patients who underwent multi-level lumbar or lumbosacral posterolateral fusion with posterior instrumentation. The outcomes were deemed either 'good' or 'bad' based on clinical and radiological results. Many demographic and radiological factors were analyzed to examine potential risk factors for poor outcomes. Student t-test, Fisher exact test, and the chi-square test were used based on the nature of the variables. Multiple logistic regression analysis was used to exclude confounding factors.
RESULTS
Twenty cases showed a good outcome (group A, 54.1%) and 17 cases showed a bad outcome (group B, 45.9%). The overall fusion rate was 70.3%. The revision procedures (group A: 1/20, 5.0%; group B: 4/17, 23.5%), proximal fusion to L2 (group A: 5/20, 25.0%; group B: 10/17, 58.8%), and severity of stenosis (group A: 12/19, 63.3%; group B: 3/11, 27.3%) were adopted as possible related factors to the outcome in univariate analysis. Multiple logistic regression analysis revealed that only the proximal fusion level (superior instrumented vertebra, SIV) was a significant risk factor. The cases in which SIV was L2 showed inferior outcomes than those in which SIV was L3. The odds ratio was 6.562 (95% confidence interval, 1.259 to 34.203).
CONCLUSIONS
The overall outcome of multi-level lumbar or lumbosacral posterolateral fusion was not as high as we had hoped it would be. Whether the SIV was L2 or L3 was the only significant risk factor identified for poor outcomes in multi-level lumbar or lumbosacral posterolateral fusion in the current study. Thus, the authors recommend that proximal fusion levels be carefully determined when multi-level lumbar fusions are considered.

Keyword

Lumbar vertebrae; Spinal stenosis; Spinal fusion; Risk factors

MeSH Terms

Aged
Female
Humans
Lumbar Vertebrae/surgery
Lumbosacral Region
Magnetic Resonance Imaging
Male
Middle Aged
Retrospective Studies
Risk Factors
Scoliosis/complications/surgery
Spinal Fusion/methods
Spinal Stenosis/complications/diagnosis/*surgery
Spondylolisthesis/complications/surgery
Treatment Outcome

Figure

• 

  Fig. 1 Measurements of radiological parameters. (A) The horizontal tilt was measured as the angle between the upper end plates of the superior instrumented vertebra (SIV) and the lines linking the top of both iliac crests on the lumbar standing anteroposterior radiograph (arrow). (B) Lumbar lordosis was measured as the angle between the superior endplates of L1 and S1 (arrow). The disc height and segmental angle directly above the level of SIV are illustrated as a white asterisk and a black asterisk, respectively.

• 

  Fig. 2 Comparisons of numeric rating scales (NRS) between 'good' group and 'bad' group in each period. (A) The NRS regarding radiating pain. (B) The NRS regarding low back pain. Preop: preoperative, PO: postoperative.

• 

  Fig. 3 A 70-year-old female patient who suffered from severe back pain and radiating pain after lumbar posterolateral fusion from L3 to L5 level at another hospital. Preoperative anteroposterior (A) and lateral (B) radiographs showed disc space narrowing (arrow) just above the level of superior instrumented vertebra. Postoperative anteroposterior (C) and lateral (D) radiographs. (E) The lateral radiograph at 9 months postoperative revealed progression of disc space narrowing at the L1-2 level (arrow). (F,G) Revision operation was performed to relieve severe back pain and radiating pain.

• 

  Fig. 4 Comparison of the direction of vertical forces by weight between the cases where superior instrumented vertebra (SIV) is L2 and L3. If SIV is L3, the translational force will be minimal because the upper end plates of L3 are nearly parallel to the ground in standing positions. If SIV is L2, the translational force (*) will be increased because the vector of the vertical force is divided by the vector which is perpendicular and parallel to the upper end plates of L2 by lumbar lordosis (arrow means gravity force to each disc level).

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