Abstract
Objective: To report a new method for reduction and stabilisation of a high grade isthmic spondylolisthesis.
Design: Case study
Subjects: A 14 year old boy presented with persistent low back pain from an L5/S1 grade 3 isthmic spondylolisthesis. MRI scan confirmed the L5/S1 spondylolisthesis with a degenerative disc at this level and healthy discs above. After discussion with the patient and his family, it was decided to attempt to reduce the spondylolisthesis.
Operation: Surface SSEP and CMEP were performed throughout the procedure. The patient was positioned prone on a Montreal frame and a standard posterior, midline approach made from L4 to the sacrum with careful preservation of the L4/5 facet joints. Wide laminectomy at L5, with partial laminectomy of the superior aspect of S1 and the inferior aspect of L4 allowed visualisation of the L5, S1 and S2 nerve roots. The postero-superior aspect of S1 was removed with an osteotome from each side in preparation for the reduction of L5. An L5/S1 discectomy and end-plate preparation was performed in preparation for a PLIF. Reduction was not possible at this stage. The wound was closed and the patient re-positioned supine. A transperitoneal approach was made to L5/S1 allowing removal of the anterior disc protrusion and associated fibrosis. Following careful removal of this material, L5 could be translated posteriorly. The anterior approach was closed and the patient was repositioned prone with the posterior wound re-opened. Pedicle screws were inserted into S1 bilaterally but it was not possible to get pedicle screws into the deep seated and dysplastic L5 pedicles so screws were placed in the L4 pedicles. Contoured rods (5mm) were placed into the S1 screws. After very mild distraction, the screw in L4 on one side was reduced to the rod allowing placement of an L5 pedicle screw on the opposite side. This process was repeated to allow placement of a second L5 pedicle screw on the other side. The plan was to the remove the L4 pedicle screws to avoid fusing the L4/5 level. Unfortunately, due to the dysplastic pedicles, the L4/5 facet joints were destroyed by the pedicle screw insertion and an L4 to S1 fusion performed. Iliac crest bone graft was harvested for the posterolateral fusion and also used to fill two Rotafix cages inserted into the reduced L5/S1 disc space. A radiograph at this stage confirmed reduction of the L5/S1 spondylolisthesis. Total estimated blood loss was 4200ml and a cell saver system was used throughout the operation. The patient had no neurological deficit after surgery and made an uneventful recovery being discharged 4 days after surgery. There was a haematoma/seroma beneath a well healed wound noted at the six week clinic appointment but no other complications have been observed. He is delighted with his improved cosmetic appearance and his back pain has resolved.
Conclusions: We feel this single operation, three stage procedure is a safe way of reducing a high grade spondylolisthesis.
The abstracts were prepared by Mr Peter Millner. Correspondence should be addressed to Peter Millner, Consultant Spinal Surgeon, Orthopaedic Surgery, Chancellor Wing, Ward 28 Office Suite, St James’ University Hospital, Beckett Street, Leeds LS9 7TF.
