Inclusion of patients
A retrospective study was conducted on the clinical data of 142 patients with TOLF and laminectomy in the Spine surgery of the XXX Medical University from January 2003 to January 2018. Inclusion criteria: 1. Patients with OLF undergoing laminectomy; 2. Complete clinical data; 3. The last follow-up of two years or more. Exclusion criteria:1. Combined with anterior disc herniation, obvious compression of spinal cord or nerve root; 2. Combined with other spinal cord related diseases;3. Trauma, inflammation, infection, tumor involving the spine; 4. Patients with severe compression of cervical or lumbar nerves. Of the 142 patients included in the study(male 89, female 53). According to whether the laminectomy was combined with instrumentation, the patients were divided into two groups: group A (laminectomy alone LA, n = 77) and group B (laminectomy with instrumentation LI, n = 65).
Ethics Committee of The XXX Medical University approved the study, and written informed consents were obtained from all patients before they were recorded.
Study Variables
Age, Sex, BMI, Smoking, Drinking, Heart disease, Hypertension, and Diabetes were collected by different staffs at the time of admission. Preoperative symptoms (Gait disturbance, Thoracic and back pain, Numbness in LE, Pain in LE, Sensory deficit in LE, Urination disorder, Sense of constriction in thoracic or abdomen) were recorded in the physical examination was performed. Operation-related variables includeed: Preoperative duration of symptoms, OLF segment, Intramedullary signal change on MRI, Dural ossification, Residual rate of cross-sectional spinal canal area on CT, Shape on the sgittal MRI, Operation time, Blood loss, Pre-mJOA, Post-mJOA, JOA improvement rate.
Operation Method
The same group of surgeons performed the operation. The patient was in the prone position under general anesthesia. Monitoring of electromyography and somatosensory evoked potentials during operation was applied. Operation segment confirmed by C-arm fluoroscopy.Make a posterior median incision along the spinous process,the skin and subcutaneous tissue were separated layer by layer, and the structures of spinous process, lamina and articular process were exposed.(For patients underwent laminectomy with instrumentation, pedicle screws were screwed first.)First, the spinous process and the outer layer of the lamina were bited off, and then the lateral lamina were removed by high-speed grinding drill in the longitudinal direction at the inner edge of the facet joints of the bilateral lamina. Then, the interspace of the lamina was enlarged, and the ligaments between the upper and lower spine were removed,and then used a high-speed grinding drill to scan the middle lamina with normal saline flushing, and did not polish each line too deeply until the ossified tissues were eggshell-like translucent. The remaining thin layer of bone was lifted with towelet forceps, and the inner vertebral plate, ossified ligamentum flavum and dural mater were gently probed with nerve exfoliator to see if there was adhesion. If there was no adhesion, the inner vertebral plate and ossified ligamentum flavum would be removed to achieve full decompression. Continued to nibble on both sides to the outer 1/3of the facet joint, exposed both sides of the dural sac, at this time the dural sac could be completely expanded. In this study, 16 patients (4 cases in group A and 12 cases in group B) were found to have heavy adhesion to the dura mater, which could not be separated.
They were resected together and repaired with local fascia.
After decompression was completed, (The patients who underwent laminectomy and internal fixation installed the pre-bent connecting rod on the pedicle screw and tightened and locked it.), rinse the operation field thoroughly, indwelling negative pressure drainage tube, suture the incision layer by layer, and the operation was finished. All patients were routinely treated with antibiotics within 3 days after operation. 7 days after operation, patients were encouraged to wear braces to move under the ground, and brace protection was maintained for about 3 months.
Satisfaction Evaluation
All patients were followed up by outpatient or telephone at 6 months, 1 year, and 2 years postoperatively. The neurological function was evaluated by the Japanese Orthopaedic Association (JOA) score during the follow-up.Thoracic neurological function JOA score (out of 11) was improved by cervical JOA score (out of 17) [11–12], 4 points on dexterity of hands and 2 points on sensation of upper limbs were removed based on cervical JOA score (Table 1). Japanese Orthopaedic Association recovery rates were calculated as follows: [(postoperative JOA score - preoperative JOA score)/(11 - preoperative JOA score)]×100%. Recovery outcome was ranked as excellent(≥ 75%), good(50%-74%), generally(25%-49%), poor(༜25%) [10]. During the follow-up, anterior and lateral X-ray and Three-dimensional CT were taken.
Table 1 .
Modified Japanese Orthopaedic Association (JOA) scoring system for the assessment of thoracic myelopathy. (Total score 11 points)
Functional score
Motor function: lower limb
0 Unable to walk.
1 Support was needed to walk on flat ground.
2 Need a cane or aid on flat ground.
3 Walking on flat ground or up stairs did not require support,
but the lower limbs were not flexible.
4 Normal.
Sensory function: lower limb
0 Obvious sensory impairment.
1 Mild sensory impairment or numbness.
2 Normal.
Sensory function: Trunk
0 Obvious sensory impairment.
1 Mild sensory impairment or numbness.
2 Normal.
Bladder function
0 Uroschesis.
1 Highly dysuria, laborious, irretention or incontinence.
2 Mild dysuria, frequent urination, hesitation in urination.
3 Normal.
Statistical analysis
All statistical analyses were carried out by SPSS software version 22.0 (IBM, Armonk, NY, USA), and the test level was α = 0.05.The measurement data between the two groups were compared by independent sample t-test or non-parametric test according to whether they were in line with normal distribution and homogeneity of variance. Analysis of counting data by chi-square test.Significance was accepted for a p value < 0.05.