Abstract
Introduction: Spinous process osteotomy (SPO) and multiple laminotomy can be used for multi-level lumbar decompression. We conducted an experimental study to compare the effects of these two methods on spinal kinetics.
Method: Ten fresh calf spines (L2- sacrum) were mounted in dental stone and segmental motion of L3 relative to L5 was assessed using an electromagnetic 3-D motion detection system (FASTRAK, Polhemus, Colchester, VT, USA). Pure moments of 0, 2.5, 5, 7, and 10 Nm were used in flexion/extension, right/left lateral bending, and right/left axial rotation. The moments were generated by applying two equal and opposite forces (weights) to the perimeter of a plastic circular disc, which was fixed to the superior end plate of L3 by three screws. In five spines decompression was performed at L3/4 and 4/5 using standard laminotomy technique. Decompression using SPO was done at L3–5 through a unilateral approach in the rest. Segmental mobility between the two methods was compared using the Mann-Whitney test.
Results: Mean range of motion in the specimens before intervention was-lateral bending (32.70 ± 7.6 SD), rotation (13.10 ± 4.8 SD), flexion/extension (19.30 ± 7.1 SD). There was statistically significant difference between mean increase in lateral bending after SPO to that following laminotomy (4.00 ± 1.5 SD vs 0.60 ± 1.6 SD; p=0.008). Mean increase in flexion- extension after SPO was not significantly different from that after laminotomy (4.50 ± 1.1 SD vs 3.90 ± 3.8 SD; p= 0.75). There was no difference in the mean increase in axial rotation after SPO compared to that following laminotomy (7.90 ± 3.6 SD vs 6.80 ± 5.0 SD; p= 0.75).
Conclusions: Both laminotomy and SPO produced increased range of motion in a calf spine model. SPO produced significant increase in lateral bending although its clinical significance is unknown.
Ethics approval: none
Interest Statement: Local grant (Research Fund, Centre for Spinal Studies, Robert Jones and Agnes Hunt Hospital, UK
Correspondence should be addressed to BASS/BCSS c/o BOA, at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London, WC2A 3PE, England.
