Article
Shape of the spinal canal in lumbar stenosis does not predict surgical outcome
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Authors
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Monika Horanin
- Klinik für Neurochirurgie, Universitätsmedizin Göttingen, Germany
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Bawarjan Schatlo
- Klinik für Neurochirurgie, Universitätsmedizin Göttingen, Germany
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Veit Rohde
- Klinik für Neurochirurgie, Universitätsmedizin Göttingen, Germany
| Published: | June 8, 2016 |
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Outline
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Objective: Lumbar spinal stenosis is one of the most frequent neurosurgical affections. It has been argued that the anatomical shape of the spinal canal predicts outcome. Three types of segmental anatomy have been described: oval, round and trefoil. It was suggested that the necessity to perform a bilateral decompression should be made based on this distinction in one level-decompression surgery. We routinely perform a unilateral microsurgical approach with undercutting to decompress both sides of the spinal canal. The aim of the current study is to assess whether this anatomical distinction into oval, round and trefoil-shaped spinal canal is of relevance when routine bilateral decompression is performed.
Method: We performed a retrospective chart review of patients undergoing lumbar decompression surgery. Spinal canal configuration was assessed based on maximal transverse and anterior-posterior diameter and shapes were classified accordingly into oval, trefoil and round. Associations between canal shape and outcome improvement (aggregate of walking distance and leg pain) were tested using receiver-operator curve analysis and Chi2 evaluation.
Results: A total of 236 lumbar levels were operated on in 159 patients. Mean age was 71± 9 years. Mean BMI was 29.3 ± 6 and the average no. of operated segments was 1.3 ± 0.6. Oval shaped configurations were detected in 155 (65%; L1/2: 67%, L2/3: 96%, L3/4: 73%, L4/5: 57%, L5/S1: 0%). Round shaped segments constituted 11 (5%; L1/2: 0%, L2/3: 0%, L3/4: 8%, L4/5: 3%, L5/S1: 0%) and trefoil-shaped segments 70 (30%; L1/2: 33%, L2/3: 4%, L3/4: 19%, L4/5: 39%, L5/S1: 100%) levels. There was no correlation between improvement in walking distance or lumbar pain and shape of the spinal canal (Pearson Chi2, p=0.319) with insignificant areas under the curve regardless of shape (trefoil: 0.505; oval: 0.506; round: 0.395).
Conclusions: Our results suggest that the configuration of the spinal canal, particularly the nomenclature of oval, round and trefoil is an anatomical function varying in frequency with lumbar segment. Our results do not support the notion that the classification should influence surgical decision-making.
