Sciatic scoliosis is a clinical syndrome resulting from a minor painful lesion in the muscles, fasciae or ligaments of the lower back, the intervertebral or sacroiliac joints, or a sciatica. It is characterized by a lateral tilt of the trunk and a variable disability [1, 5]. In 1973, Finneson proposed that the topographical position of disc herniation in association with the exiting spinal nerve accounts for the displacement [6]. In contrast, when the herniation is located medial to the nerve root, and patient will tilt toward the side of the sciatica to decrease nerve root compression. However, previous studies have demonstrated that the mentioned hypothesis is contradicted to clinical results [1, 3]. Matsui et al. [1] found that sciatic scoliosis may occur with the convexity to the symptomatic side of disc herniation at any topographic location of disc herniation. Suk et al. [3] reported that the direction of sciatic scoliosis was not related to the location of nerve root compression, while it was associated with the side of disc herniation. In the present study, there was a significant association between the side of the disc herniation and the direction of sciatic scoliosis (P = 0.036), which is consistent with previously reported findings. This phenomenon can be explained by the autonomic decompression mechanism that was presented by Suk et al. [3]. They concluded that the herniated disc could be reduced in size by stretching or inward bulging at the convex side of the scoliosis.
Sciatic scoliosis caused by LDH could be improved once the irritation of the nerve root is relieved [1, 3, 7, 8]. Previous researches pointed out that open discectomy surgery has exhibited a great success [3, 8, 9]. However, patients with sciatic scoliosis caused by LDH typically aged between 20 and 40 years old, are in good health, and are often very muscular and vigorous [8]. The open surgery can lead to an important injury to such patients, which may increase the complication rate. In order to relieve the injury, we used the MIS-TLIF technique to treat patients with sciatic scoliosis caused by LDH.
The MIS-TLIF technique was first presented by Foley [10], who utilized tubular retractors under radiological guidance by a muscle-dilating approach. This method can reduce the amount of iatrogenic muscle and soft tissue injuries, which was confirmed by several surgeons [11, 12]. According to the literatures, compared with the traditional open surgery, the MIS-TLIF technique generally possesses minimal blood loss. In the present study, clinical and radiographic results demonstrated that application of MIS-TLIF technique to treat such patients is safe and effective. Previously reported clinical outcomes demonstrated that MIS-TLIF technique for patients with sciatic scoliosis caused by LDH could be associated with shorter operative time, remarkably less blood loss, and shorter length of stay at hospital [12, 13], which may result in significantly lower morbidity, cost, and earlier rehabilitation of the patients. The improved VAS and ODI scores indicated that MIS-TLIF technique could be helpful to achieve a satisfactory decompression, instrumentation and fusion with less injury, relieve patients’ pain, and gain satisfactory clinical outcomes.
Patients with sciatic scoliosis caused by LDH commonly experience coronal and sagittal imbalance [3, 8, 14, 15, 16]. Previous studies demonstrated that the open discectomy surgery can achieve satisfactory imbalance correction [3, 8]. Kim et al. [12, 13] pointed out that improvement of balance by percutaneous lumbar endoscopic discectomy exhibited less therapeutic efficacy than open discectomy surgery. Suk et al. [3] suggested that the improved correction of scoliosis not only could be achieved by removal of the herniated disc, but also by the removal of hypertrophic ligamentum flavum, hypertrophied medial facet, and decompression of the narrow nerve root foramen after exploration of the nerve root during surgery. Thus, a complete decompression is highly essential, and is the most important procedure for the correction of imbalance. In the current research, the coronal balance returned to normal. The C7PL-CSVL improved from 3.36 ± 1.7 cm to 0.69 ± 0.47 cm, and the Cobb angle was elevated from 15.6 ± 4.3° to 3.8 ± 2°. Except for the coronal balance, the sagittal balance was remarkably improved, which may be helpful for patients in the long run. The LL increased from − 23.1 ± 9.4° to -36.1 ± 7.5°. The PT reduced from 29 ± 9.1° to 19.8 ± 4.5°. The SS varied from 23.2 ± 6.34° to 32.4 ± 7°. The change of the parameters demonstrated that MIS-TLIF technique could achieve a satisfactory imbalance correction.
There is a limitation in the present study. Due to the complicated nature of sciatic scoliosis, it may be difficult for junior physicians to truly employ MIS-TLIF technique, which may lead to increase duration of surgery and blood loss.