The clinical effectiveness and complications of lumbar selective fenestration and concave-side fusion (LSFCF) in degenerative lumbar scoliosis (DLS) combined with lumbar spinal stenosis (LSS)

This is a retrospective study.

This study has been approved by the ethics committee of Shanghai Changzheng Hospital. We retrospectively reviewed the data of patients with DLS who underwent surgical treatment in our hospital from January 2018 to March 2020.

The inclusion criteria

(1) All patients had different degrees of chronic low back pain and neurological symptoms of lower extremities (neurogenic claudication or sensory or/and motor symptoms or cauda equina syndrome), and multi-segmental LSS was demonstrated by MRI; (2) Presence of adult scoliosis, defined by a coronal Cobb angle above 10°; (3) all patients had no significant improvement after conservative treatment for at least 6 months; (4) patients aged 50 years and over.

The exclusion criteria

(1) History of lumbar spinal surgery; (2) other spinal diseases (e.g., ankylosing spondylitis, spine tumor, fracture, or neurologic disorders); (3) unwillingness to complete study questionnaires; (4) non-adherence to clinical and radiographic follow-up protocols.

A total of 26 eligible patients (mean age, 64.73 y; 17 men, 9 women) were enrolled in the current study based on data of our department. In the current study, patients underwent LSFCF included 4 cases with 5 operated levels, 11 cases with 4 operated levels, 9 cases with 3 operated levels and 2 cases with 2 operated levels (Table 1). The average follow-up period of the patients was 20.14 ± 5.21 months.

The clinical effects were evaluated by visual analogue scale (VAS) and Oswestry disability index (ODI) [10, 14]. In addition, the operated levels, the blood loss and operative time were also evaluated. We obtained and evaluated the VAS and ODI scores of patients before and immediately after surgery, 3 months, 6 months, 1 year after surgery, and at the end of follow-up period. In addition, the operated levels, the blood loss, operative time and adverse events were also recorded.

Imaging examinations were performed preoperatively and at the final follow-up postoperatively, including measurement of cobb angle, lumbar lordosis (LL), pelvic tilt (PT), apical vertebral translation (AVT), coronal vertical axis (CVA), sagittal vertical axis (SVA), sacral slope (SS) and pelvic incidence (PI). The radiological parameters were recorded before surgery and at the last follow-up after surgery. The cobb angle is formed by the intersection of two lines constructed from the superior and inferior vertebrae of the scoliosis curve. The LL is defined by the angle between the upper plane of the L1 lumbar vertebrae and the upper plane of the S1 sacral vertebrae. The PT is defined as the angle created by a line running from the sacral endplate midpoint to the center of the bifemoral heads and the vertical axis. The AVT is defined as the distance between the center of lumbar apical vertebra and central sacral vertical line (CSVL). The CVA is defined as the horizontal distance measured from a vertical plumb line centered in the middle of the C7 vertebral body to the CSVL. The SVA is measured as the distance between the C-7 plumb line and the posterior superior aspect of the S1 [15, 16]. The SS is defined as the angle between the sacral plate and the horizontal plane [17, 18]. The PI is defined as the angle between the line perpendicular to the sacral plate at its midpoint and the line connecting this point to the femoral head’s axis [18].

The procedures of LSFCF were as follows: (1) after the success of anesthesia, the patients were placed in a prone position on the operating table. Take the operated level of L3–S1 for an example. Expose the L3–S1 facet joints and the lamina of the operated level bilaterally; (2) the L3–S1 pedicle screw fixation was performed bilaterally (Tianjin Zhengtian Medical Instrument Co., Ltd, China); (3) fenestration of the L3/4 level on the symptomatic side: decompression range should include medial to dorsal dural, lateral to L4 nerve root, cephalic to upper L4 nerve root sleeve, and caudal to L4 nerve root canal; (4) the interbody fusion was then performed following three principles: Firstly, if the symptomatic side of L3/4 is located on the concave side of the scoliosis, interbody fusion should be performed on the same side. In the meanwhile, on the asymptomatic side, decompression was not performed, and therefore the spinous process, interspinous ligament and lamina were preserved to maintain integrity of posterior spinal structures to the maximum; Secondly, if the symptomatic side of the segment is located on the convex side of the scoliosis, interbody fusion should be performed on the opposite side, that is, the concave side. Under this circumstance, fenestration on the opposite side should be performed; Thirdly, if the patient has sensory or motor impairment in both lower limbs, bilateral fenestration should be adopted, and interbody fusion should be performed on the concave side. The role of these principles is to ensure that interbody fusion is always performed on the concave side of the scoliosis. The cages used in this study were all manufactured by Johnson & Johnson (China) Medical Equipment Co., Ltd or Double Medical Technology Inc, China; (5) the L4/L5 and L5/S1 were managed in the same way; (6) the intraoperative fluoroscopy was used to confirm the good position of the screws; (7) special attention should be paid to the fact that convex compression and concave distraction were not performed after interbody fusion. All patients were immobilized in a waist support for 12 weeks postoperatively.

Independent sample t-test was used to compare the mean value of VAS or ODI scores before and after surgery. The SPSS software for Windows (ver. 26.0; SPSS Inc, Chicago, IL, USA) was used to analyze the clinical data of patients. P < 0.05 was accepted as indicative of significant differences.

The operation time and blood loss of patients underwent LSFCF were 129.33 ± 15.74 min and 356.13 ± 21.28 ml. The VAS and ODI scores significantly improved from 8.04 ± 0.91 preoperatively to 1.62 ± 0.74 postoperatively, and from 61.33 ± 18.47 preoperatively to 39.24 ± 13.58 postoperatively (P < 0.05). There was one patient with venous thrombosis in lower extremities (3.85%), pneumonia (3.85%) and urinary tract infection (3.85%) after surgery, respectively (Table 2). The overall complication rate was 11.54% and all patients were cured by conservative treatment before discharge. There was no case with cerebrospinal fluid leakage, cage subsidence, displacement, etc. during the follow-up period. No patients underwent secondary surgery during follow-up period and bony fusion was achieved in each patient at the final follow-up.

There was a significant improvement in cobb angles from 27.38 ± 5.24° preoperatively to 10.03 ± 3.13° at the final follow-up postoperatively (P < 0.05, Table 3). In the meanwhile, the LL significantly increased from 26.84 ± 4.38° preoperatively to 38.92 ± 4.46° at the final follow-up postoperatively (P < 0.05, Figs. 1, 2). Furthermore, the PT showed a significant decrease from 26.19 ± 3.09° preoperatively to 19.54 ± 2.35° at final follow-up postoperatively (P < 0.05). Finally, the AVT, CVA and SVA demonstrated significant improvements from 8.37 ± 2.41 mm to 3.83 ± 1.92 mm, from 27.18 ± 4.83 mm to 11.25 ± 2.74 mm, and from 32.87 ± 4.71 mm to 16.74 ± 3.22 mm at final follow-up postoperatively (P < 0.05). The SS exhibited an significant increase from 38.27 ± 7.37° to 44.73 ± 8.05° (P < 0.05), however, there is no significant change in the value of PI (P > 0.05).