Scoliosis in dysplastic spondylolisthesis: a clinical survey of 50 young patients

Abstract

Background: Dysplastic spondylolisthesis is a rare spinal deformity that occurs mainly in young patients. Although its sagittal parameters had been well stated, coronal abnormalities in these patients were poorly studied. The purposes of this study were: (1) to investigate the prevalence of scoliosis in dysplastic spondylolisthesis;(2) to assess scoliosis resolution or persistence after surgery; and (3) to propose a modified classification of scoliosis associated with dysplastic spondylolisthesis.

Methods: Fifty patients (average age 14.9 ± 5.6 years) diagnosed with dysplastic spondylolisthesis who underwent surgical treatment were followed up and their data were analyzed. Standing posteroanterior and lateral full spine radiographs were used to measure the coronal and sagittal parameters. Patients with scoliosis, which was defined as a coronal Cobb angle greater than 10°, were divided into three groups according to their curve characteristics: "independent" scoliosis (IS) group, spasm scoliosis (SS) group, and olisthetic scoliosis (OS) group. SS and OS were spondylolisthesis-induced scoliosis. The radiographic parameters and patient-reported outcomes were collected before and after surgery and compared between groups.

Results: The average slip percentage was 62.8% ± 23.1% and the average follow-up time was 51.5 ± 36.4 months (range 3-168 months). Twenty-eight of the 50 (56%) dysplastic spondylolisthesis patients showed scoliosis, of which 8 were IS (24.7° ± 15.2°), 11 were SS (13.9° ± 3.0°), and 9 were OS (12.9° ± 1.9°). By the last follow-up, no scoliosis resolution was observed in the IS group whereas all SS patients were relieved. Of the nine patients with OS, four (44.4%) had scoliosis resolution after surgery.

Conclusion: Distinguishing different types of scoliosis in dysplastic spondylolisthesis patients may help surgeons to plan treatment and understand prognosis. For patients with significant scoliosis, whether "independent" or spondylolisthesis-induced, treatment of spondylolisthesis should be performed first and scoliosis should be observed for a period of time and treated according to the corresponding principles.

Keywords: Adolescent idiopathic scoliosis; Developmental spondylolisthesis; Dysplastic spondylolisthesis; Olisthetic scoliosis; Spasm scoliosis.

Fig. 1

The mechanism of the development of olisthetic scoliosis, showing the rotation (A) of L5 on the axial plane and the tilt (B) of L5 on the coronal plane during slipping

Fig. 2

A: A 16-year-old female with dysplastic spondylolisthesis (Grade III) and adolescent idiopathic scoliosis (15°). B: A 12-year-old female with dysplastic spondylolisthesis (Grade V) and syndromic scoliosis (44°); she was diagnosed with Marfan Syndrome before surgery

Fig. 3

A 12-year-old male with dysplastic spondylolisthesis (Grade III) and spasm scoliosis with a tilted body, long curve span, and no vertebral rotation

Fig. 4

A 12-year-old female with dysplastic spondylolisthesis (Grade III) and olisthetic spondylolisthesis. A: Preoperative radiograph shows the lower lumbar curve with lower lumbar vertebral tilt and rotation. B: Coronal reconstructive CT scan showing L5 vertebra tilt relative to S1. C: Axial CT scan showing L5 rotation relative to S1

Fig. 5

A 13-year-old female with dysplastic spondylolisthesis (grade III) and idiopathic scoliosis. A: Preoperative radiograph demonstrated obvious trunk tilt and vertebral rotation at the thoracolumbar spine; we believe the scoliosis was composed of idiopathic scoliosis and spondylolisthesis-induced scoliosis (54°). B: Postoperative radiograph at two-year follow-up shows relief of spondylolisthesis-induced scoliosis with normal coronal balance, while the idiopathic scoliosis was restored to its “original” shape (43°)

Fig. 6

A flowchart to distinguish the different types of Modified Crostelli’s Classification of scoliosis associated with spondylolisthesis

Fig. 7

An 11-year-old female with dysplastic spondylolisthesis (grade IV) and sciatic scoliosis greater than 20°. A: The preoperative radiograph shows obvious scoliosis (24°) and coronal imbalance, without vertebral rotation. B: The one-year follow-up radiograph shows scoliosis resolution after spondylolisthesis surgery.