Surgical technique of spine-shortening vertebral osteotomy for adult tethered cord syndrome: a case report and review of the literature

Abstract

Background: Miyakoshi et al. reported three cases of tethered cord syndrome treated by spine-shortening vertebral osteotomy, which provided relief of the patients' symptoms with no complications. Although the details of these cases were described in a previous report, the surgical technique was not thoroughly explained. In the present report, we describe the details of our procedure with reference to a fourth case.

Case presentation: A 47-year-old Asian woman was admitted to our hospital with a 1-year history of worsening leg numbness and urinary dysfunction. Magnetic resonance imaging revealed a low-lying conus medullaris extending to the level of S2 and surrounded by fat tissue at that level. We diagnosed her condition as adult tethered cord syndrome, and spine-shortening vertebral osteotomy was planned. The target level for the osteotomy was L2. Bilateral pedicle screw implants were placed at L1 and L3 using an anterior-posterior image intensifier. In this procedure, it is essential to use monoaxial screws inserted exactly parallel to the rostral endplates of each vertebral body; this ensures appropriate alignment between the L1 caudal endplate and the L2 osteotomy surface. The upper one-third of the lamina of L2 was resected, and the bilateral two-thirds of the pedicle of L2 was removed with a surgical air drill. After exposure of the lateral side of the L1-2 disc, discectomy was performed with a knife and curette. Following complete discectomy of L1-2, the upper vertebral body of L2 was removed with a surgical air drill. After complete removal of the vertebral body, a straight rod was connected to two screws and applied pressure between the screws. Two polyethylene tapes were applied to the L2 lamina and bilateral rods.

Conclusion: Spine-shortening osteotomy that preserves the caudal one-third of the pedicle and lamina with one-above and one-below instrumentation successfully reduced the spinal cord tension without causing neural damage.

Keywords: Adult tethered cord syndrome; Case report; Spine-shortening vertebral osteotomy; Surgical technique.

Fig. 1

Preoperative lumbar magnetic resonance images of a 47-year-old woman. Magnetic resonance imaging revealed a low-lying conus medullaris extending to the level of S2 and surrounded by fat tissue at that level. a T1 sagittal image. b T2 sagittal image. c T2 axial image

Fig. 2

A drawing of the surgical procedure of shortening osteotomy. a Posterior image. The black shadow shows the area of the osteotomy. b Postoperative image. c Lateral image. The black shadow shows the area of the osteotomy. d Postoperative lateral image. During this procedure, it is essential to use monoaxial screws inserted exactly parallel to the rostral endplates of the vertebral bodies. Taping to the L2 lamina and bilateral rods makes the osteotomy site biomechanically stable

Fig. 3

Preoperative and postoperative radiographs. a Preoperative lateral radiograph. b Postoperative anteroposterior radiograph. c The postoperative lateral radiograph shows 18-mm shortening of the spine compared with the preoperative radiograph

Fig. 4

One-year postoperative computed tomography images. a Sagittal reconstruction image. b Coronal reconstruction image. Complete bone union was achieved