The Safety and Effectiveness of Multi-Segment Cortical Bone Trajectory Screws in Adult Degenerative Scoliosis with Stenosis Among the Elderly: Minimum 5-year Follow-up Study

Abstract

Purpose: To evaluate the long-term efficacy and safety of multi-segment cortical bone trajectory screws for treating mild adult degenerative scoliosis with stenosis among the elderly.

Patients and methods: From January 2018 to December 2019, a total of 41 patients of mild adult degenerative scoliosis with stenosis underwent posterior lumbar decompression, bone graft fusion, and internal fixation, which were retrospectively divided into pedicle screw (PS) group and cortical bone trajectory (CBT) screw group according to different internal fixation methods. The operation time, intraoperative blood loss, immobilization, and length of hospital stay were compared between the two groups. The visual analog score (VAS) of low back and leg pain, Oswestry disability index (ODI), Cobb angle, lumbar lordosis (LL) angle, apex vertebral translation (AVT), coronal balance distance (CBD) and sagittal vertical axis (SVA) were compared between the two groups preoperatively and 6 months, 1 year, 5 years postoperatively. Perioperative and follow-up complications were observed.

Results: The CBT group was superior to PS group in operation time, intraoperative blood loss, immobilization, length of hospital stay (P<0.05). The low back VAS and ODI in CBT group were significantly lower than those in PS group at 6 months, 1 year and 5 years postoperatively (P<0.05). The leg VAS in CBT group was lower than PS group at 5 years postoperatively (P<0.05). The incidence of screw loosening and adjacent segment disease 5 years postoperatively in CBT group was significantly lower than that in PS group (P<0.05).

Conclusion: Multi-segment cortical bone trajectory screws is a safe and effective treatment option for mild adult degenerative scoliosis with stenosis among the elderly. This technique features miniinvasive trauma and quick recovery, which might lead to improved long-term quality of life and a reduction in screw loosening and adjacent segment disease rates.

Keywords: adult degenerative scoliosis; cortical bone trajectory screw; elderly; stenosis.

Figure 1

Illustrative case of adult degenerative scoliosis with stenosis (CBT group). Preoperative X-ray: mild scoliosis, lumbar multi-level disc space narrowing (a and b); preoperative CT: Multi-level lumbar disc degeneration (c); preoperative MRI: multi-level lumbar spinal stenosis (L2/3, L3/4, L4/5), bilateral ligamentum flavum hyperplasia and hypertrophy pressing dural sac, bilateral facet joint hyperplasia and cohesion (d and e); X-ray immediately postoperatively: internal fixation system firmly in place (f and g); CT immediately postoperatively: CBT screws in good position (h); X-ray 5 years postoperatively: scoliosis not aggravated (I and j); CT 5 years postoperatively: “corticalization” phenomenon around screws (red arrows), no loosening of screws (k); MRI 5 years postoperatively: adequate spinal canal decompression, no radiographic ASD occur (l–n).

Figure 2

Illustrative case of adult degenerative scoliosis with stenosis (CBT group). Preoperative X-ray: mild scoliosis, lumbar multi-level disc space stenosis, osteophyte hyperplasia (a and b); preoperative CT: Lumbar multi-level intervertebral space height decreased, degeneration is obvious (c); preoperative MRI: multi-level stenosis (L2/3, L3/4, L4/5), cauda equina redundancy, dural sac compression obvious (d); X-ray immediately postoperatively: internal fixation system firmly in place (e and f); CT immediately postoperatively: CBT screws in good position (g and h); X-ray 5 years postoperatively: scoliosis not aggravated (i and j); CT 5 years postoperatively: “corticalization” phenomenon around screws (red arrows), no loosening of screws (k); MRI 5 years postoperatively: no radiographic ASD occur (l-n).

Figure 3

Illustrative case of adult degenerative scoliosis with stenosis (PS group). Preoperative X-ray: mild scoliosis, lumbar multi-level disc space stenosis (a and b); X-ray immediately postoperatively: internal fixation system firmly in place (c and d); X-ray immediately after revision surgery: screws in good position (e and f); MRI 5 years postoperatively: spinal stenosis at L5/S1 (g-k); CT immediately after revision surgery: screws in good position (l-n); X-ray 1 year after revision surgery: scoliosis not aggravated (o and p).

Figure 4

Pedicle screw placement (a); cortical bone trajectory screw placement (b).

Figure 5

Comparison of two screws in anteroposterior and lateral position (a); Comparison of two screws in axial position (b).

Figure 6

Comparison of operation time (a), blood loss (b), immobilization (c), and length of hospital stay (d) between two groups.

Figure 7

Comparison of low back VAS (a), ODI (b), and leg VAS (c) between two groups preoperatively and postoperatively.