Chang Ju Hwang

Fusion Rates of Instrumented Lumbar Spinal Arthrodesis according to Surgical Approach: A Systematic Review of Randomized Trials

Background Lumbar spine fusion rates can vary according to the surgical technique. Although many studies on spinal fusion have been conducted and reported, the heterogeneity of the study designs and data handling make it difficult to identify which approach yields the highest fusion rate. This paper reviews studies that compared the lumbosacral fusion rates achieved with different surgical techniques. Methods Relevant randomized trials comparing the fusion rates of different surgical approaches for instrumented lumbosacral spinal fusion surgery were identified through highly sensitive and targeted keyword search strategies. A methodological quality assessment was performed according to the checklist suggested by the Cochrane Collaboration Back Review Group. Qualitative analysis was performed. Results A literature search identified six randomized controlled trials (RCTs) comparing the fusion rates of different surgical approaches. One trial compared anterior lumbar interbody fusion (ALIF) plus adjunctive posterior transpedicular instrumentation with circumferential fusion and posterolateral fusion (PLF) with posterior lumbar interbody fusion (PLIF). Three studies compared PLF with circumferential fusion. One study compared three fusion approaches: PLF, PLIF and circumferential fusion. Conclusions One low quality RCT reported no difference in fusion rate between ALIF with posterior transpedicular instrumentation and circumferential fusion, and PLIF and circumferential fusion. There is moderate evidence suggesting no difference in fusion rate between PLF and PLIF. The evidence on the fusion rate of circumferential fusion compared to PLF from qualitative analysis was conflicting. However, no general conclusion could be made due to the scarcity of data, heterogeneity of the trials included, and some methodological defects of the six studies reviewed.

Laminar closure after classic Hirabayashi open-door laminoplasty.

Study Design. Prospective analysis of preoperative and postoperative radiological data. Objective. To assess the incidence and extent of laminar closure after Hirabayashi open-door laminoplasty, as determined by multi-detector computed tomography (CT), and to investigate the influence of this phenomenon on spinal cord compression, as shown by magnetic resonance imaging (MRI). Summary of Background Data. Although laminar closure occurs after laminoplasty, little is known about its progression or its effect on restenosis of the spinal canal. Methods. Thirty-five patients (132 laminae) underwent classic Hirabayashi laminoplasty and were followed for at least 12 months. Multi-detector CT was performed preoperatively, at 1 week, or less, and 6 months after surgery. At each level, the anteroposterior (AP) diameter of the spinal canal and the angle of the opened lamina were measured. MRI was performed preoperatively and 1 year after surgery to evaluate the severity of cord compression based on a six-grade classification system. Results. The mean AP diameter and the mean opening angle increased immediately after surgery (P <0.05 each) and decreased 6 months after surgery (P < 0.0001 each), with the AP diameter and opening angle decreasing by 9.4% and 10.2%, respectively. CT at 6 months showed fusion of the hinge in 91% of opened laminae. Segments with high-grade cord compression (grade ≥3) at 1 year showed greater decreases in AP diameter and opening angle (P < 0.05). Conclusion. After classic Hirabayashi open-door laminoplasty, opened laminae showed reclosure at 6 months, with approximately 10% decrease in AP diameter and opening angle. Postoperative lamina closure was associated with recurrent spinal cord compression, suggesting the need for other augmenting techniques that keep the laminae opened.

Optimal entry points and trajectories for cervical pedicle screw placement into subaxial cervical vertebrae

The present study was performed to determine the optimal entry points and trajectories for cervical pedicle screw insertion into C3–7. The study involved 40 patients (M:Fxa0=xa020:20) with various cervical diseases. A surgical simulation program was used to construct three-dimensional spine models from cervical spine axial CT images. Axial, sagittal, and coronal plane data were simultaneously processed to determine the ideal pedicle trajectory (a line passing through the center of the pedicle on coronal, sagittal, and transverse CT images). The optimal entry points on the lateral masses were then identified. Horizontal offsets and vertical offsets of the optimal entry points were measured from three different anatomical landmarks: the lateral notch, the center of the superior edge and the center of lateral mass. The transverse angle and sagittal angles of the ideal pedicle trajectory were measured. Using those entry points and trajectory results, virtual screws were placed into the pedicles using the simulation program, and the outcomes were evaluated. We found that at C3–6, the optimal entry point was located 2.0–2.4xa0mm medial and 0–0.8xa0mm inferior to the lateral notch. Since the difference of 1xa0mm is difficult to discern intra-operatively, for ease of remembrance, we recommend rounding off our findings to arrive at a starting point for the C3–6 pedicle screws to be 2xa0mm directly medial to the lateral notch. At C7, by contrast, the optimal entry point was 1.6xa0mm lateral and 2.5xa0mm superior to the center of lateral mass. Again, for ease of remembrance, we recommend rounding off these numbers to use a starting point for the C7 pedicle screws to be 2xa0mm lateral and 2xa0mm superior to the center of lateral mass. The average transverse angles were 45° at C3–5, 38° at C6, and 28° at C7. The entry points for each vertebra should be adjusted according to the transverse angles of pedicles. The mean sagittal angles were 7° upward at C3, and parallel to the upper end plate at C4–7. The simulation study showed that the entry point and ideal pedicle trajectory led to screw placements that were safer than those used in other studies.

Analysis of sagittal spinal alignment in 181 asymptomatic children.

Study Design: A cross-sectional study. Objectives: To determine the “normal” radiographic parameters of the sagittal profile of the spine in asymptomatic children. Summary of Background Data: There was consensus that cervical kyphosis is pathologic, but we suspected that the cervical kyphosis or loss of cervical lordosis is abnormal in asymptomatic children and adolescents. And we measured the pediatric sagittal profiles including the cervical lordosis for asymptomatic subjects. Materials and Methods: Analysis of 181 children without spinal pathology was performed. Radiographic measurements consisted of the following: cervical lordosis; thoracic kyphosis; thoracolumbar sagittal angle; thoracic apex; lumbar apex; lumbar lordosis; sacral inclination; sacral slope; pelvic tilt; and sagittal vertebral axis. Results: The mean cervical lordosis was −4.8±12.0 degrees (negative=lordotic), sagittal vertebral axis −2.1±2.4 cm, thoracic kyphosis +33.2±9.0 degrees, thoracolumbar sagittal angle 5.6±8.4 degrees, lumbar lordosis −48.8±9.0 degrees, sacral inclination 43.9±7.6 degrees, sacral slope 34.9±6.6 degrees, and pelvic tilt 9.4±6.1 degrees. One hundred nine (60.2%) patients had hypolordotic cervical spine (≥−5 degrees). Cervical kyphosis was present in 80 (44.2%) patients. Conclusions: There is significant variability in sagittal profile of the cervical spine in asymptomatic children. Cervical kyphosis was found in approximately 40% of our study cohort.

Minimum 5-year follow-up results of skipped pedicle screw fixation for flexible idiopathic scoliosis

OBJECTnThe aim of this study was to evaluate after more than 5 years the outcome of surgical treatment for flexible idiopathic scoliosis using skipped pedicle screw fixation.nnnMETHODSnFor patients with spine curves < 90° and flexibility > 20%, pedicle screws had been inserted into every other segment on the corrective side and 2-4 screws per curve had been inserted on the supportive side. The authors analyzed the results in 57 patients, including the correction rate of coronal curvature and rotational deformity, correction loss, sagittal balance, complications, blood loss, operation time, and implant costs.nnnRESULTSnThe mean Cobb angle was 54° preoperatively and 17° immediately after surgery (69% correction). At the last follow-up, the mean Cobb angle was 18° (2% correction loss). Rotation of the apical vertebra was corrected by 50% on average and showed only a 6% correction loss at the last follow-up. None of the patients had problems in maintaining sagittal balance. An adding-on phenomenon was detected in 4 patients (7%). Twelve of 14 patients with coronal decompensation showed improvement after surgery, whereas postoperative decompensation developed in 3 patients. Four patients had implant failures, and 4 had postoperative infections. The mean blood loss during surgery was 832 ml, and the mean operation time was 167 minutes. Compared with conventional methods, the authors method used up to 48% fewer screws.nnnCONCLUSIONSnSkipped pedicle screw fixation of flexible idiopathic scoliosis showed satisfactory results. This method has several advantages, including reduced blood loss, shorter operation time, and reduced cost.

Does preoperative T1 slope affect radiological and functional outcomes after cervical laminoplasty

Study Design. Retrospective comparative study. Objective. To analyze changes in the clinical and radiological factors related to cervical sagittal balance, relative to preoperative T1 slope, in patients with cervical myelopathy after laminoplasty (LP). Summary of Background Data. T1 slope is an important factor that should be considered before LP. However, until now, there have been no studies on how preoperative T1 slope affects the sagittal balance of cervical spine and various functional outcomes after LP. Methods. Seventy-six patients with cervical myelopathy (M:F ratio = 50:26; mean age = 64.7 ± 9.1 yr) underwent a cervical LP and were followed for more than 2 years. Radiological measurements were performed to analyze the following parameters: (1) C2–C7 sagittal vertical axis; (2) T1 slope; (3) C2–C7 lordosis; and (4) thoracic kyphosis. The visual analogue scale, Japanese Orthopedic Association, neck disability index, and 36-Item Short-Form Health Survey were also investigated. Patients were divided into 2 groups according to preoperative T1 slope, with the cutoff value being the median preoperative T1 slope. Changes in clinical and radiological parameters were compared between the preoperative evaluation and final visit. Results. Overall, C2–C7 sagittal vertical axis increased from 21.2 to 24.5 mm (P = 0.004) and C2–C7 lordosis decreased from 13.9° to 10.3° (P = 0.007) postoperatively. The T1 slope did not show any postoperative differences. Preoperative C2–C7 lordosis was larger in the high-T1 group (19.1°) than in the low-T1 group (9.0°). However, postoperative changes in C2–C7 sagittal vertical axis and C2–C7 lordosis did not show any between-group differences. Clinical outcomes (except neck pain) demonstrated overall improvement in both groups. Comparing changes in both groups showed no differences in neck pain, arm pain, neck disability index, or 36-Item Short-Form Health Survey physical component score between groups. Conclusion. Cervical sagittal balance is compromised after cervical LP. However, the degree of aggravation does not correlate with the preoperative T1 slope. Most clinical parameters demonstrate overall improvement regardless of preoperative T1 slope. Level of Evidence: 3

Effectiveness of the Charleston night-time bending brace in the treatment of adolescent idiopathic scoliosis.

Background: Part-time or night-time bracing has been introduced to address the poor compliance and psychological burden of full-time bracing. The results of various bracing methods vary, however, due to a lack of consistent inclusion criteria and definitions of brace effectiveness. We have evaluated the effectiveness of the Charleston night-time bending brace in the treatment of adolescent idiopathic scoliosis based on the new standardized criteria proposed by the Scoliosis Research Society. Methods: To be included in this study, patients met the following criteria proposed by the Scoliosis Research Society: diagnosis of adolescent idiopathic scoliosis, age 10 years and older when the orthosis was prescribed, Risser 0-2, a primary curve magnitude of 25 to 40 degrees, and no prior treatment. A total of 95 patients (87 girls, 8 boys) were included. Results: At skeletal maturity, 80 patients (84.2%) had 5 degrees or less curve progression and 15 (15.8%) had 6 degrees or more progression. Seven patients (7.8%) were recommended to undergo or underwent surgery before skeletal maturity. Eleven patients (12.6%) progressed beyond 45 degrees. According to these 3 criteria, the Charleston night-time brace was successful in 74 patients (77.9%). Depending on curve type, we observed success rates of 78.3% (47/60) for double, 71.4% (15/21) for thoracic, 83.3% (5/6) for thoracolumbar, and 87.5% (7/8) for lumbar curves. Success rates of 80.0% (36/45) and 76.0% (38/50) were observed in patients with curve magnitudes at bracing of 25 to 30 degrees and 31 to 40 degrees, respectively. Patients with high apex curves had a 67.6% (23/34) success rate, and those with low apex curves had 83.0% (39/47) success rate. Brace success rates among patients with initial Risser signs of 0, 1, and 2 were 68.8% (22/32), 80.6% (25/31), and 84.4% (27/32), respectively. Conclusions: Compared with the results of previous natural history and conventional brace study, the Charleston night-time bending brace is effective for the treatment of adolescent idiopathic scoliosis. Level of Evidence: Level VI.

The effect of a mismatched center of rotation on the clinical outcomes and flexion-extension range of motion: lumbar total disk replacement using mobidisc at a 5.5-year follow-up.

Study Design: Retrospective clinical and radiographic assessment of 21 levels of 18 consecutive patients treated using total lumbar disk replacement (TDR) for degenerative disk disease. Objectives: To report clinical and radiographic outcomes after TDR using the Mobidisc prosthesis. In addition, to determine whether there is a correlation between clinical and radiologic outcomes and prosthesis positioning. Summary of Background Data: TDR for lumbar degenerative disk disease is reported to provide good clinical and radiographic outcomes. However, TDR can alter the kinematics of the facet joint during flexion and extension. If prosthesis positioning is poor, the facet joint loading is increased upto 2.5-fold. No study has examined whether differences between the prosthesis center of rotation (COR) and the individual’s COR have an effect on the clinical or radiographic outcomes after TDR. Methods: A retrospective study of 21 levels from 18 consecutive degenerative disk disease patients who underwent lumbar TDR. The Mobidisc prosthesis was used in all cases. Clinical parameters measured were lower back and leg pain [both assessed using the Oswestry Disability Index (ODI)]. These parameters were measured preoperatively and at the last follow-up. Radiographic assessment involved examining standard lateral flexion/extension views taken at the preoperative, postoperative 6-month, and the last follow-up assessments to determine disk space height (DSH) and range of motion (ROM). Patient satisfaction (subjective outcome) was determined by telephone questioning. For analysis, TDR cases were categorized into 3 groups on the basis of the size of the “COR index,” which represented the difference between an individual’s inherent COR and the inherent prosthesis COR. Group 1, COR index <5 mm, consisted of 13 levels; group 2, COR index >5 mm, and <10 mm, consisted of 5 levels; and group 3, COR index >10 mm, consisted of 3 levels. Results: Overall, 77.8% of patients stated that they were highly satisfied with their surgical outcome. Low back pain visual analogue scale scores decreased from 7.61±2.17 (mean±SD) preoperatively to 2.33±2.679 at the last follow-up (P<0.001). The function increased postoperatively (ODI: 25.89±7.77 preoperative vs. 5.89±7.21 at last follow-up; P<0.001). The difference between preoperative and the last follow-up ODI was greater in group 1 than in groups 2 and 3 (P=0.034). Radiographic findings showed that TDR resulted in improved disk space height and segmental ROM (P<0.05). Analysis of the 3 groups showed that ROM preservation decreased as the COR index increased. Conclusions: The present study found that lumbar TDR using the Mobidisc prosthesis resulted in good clinical and radiologic outcomes and good patient satisfaction. Furthermore, we found that patient satisfaction, function, and ROM preservation correlated with correct COR positioning of the prosthesis.

A novel method of screw placement for extremely small thoracic pedicles in scoliosis.

Study Design. A retrospective clinical study. Objective. To introduce a novel method of pedicle screw placement for extremely small thoracic pedicles in scoliosis and evaluate the safety and accuracy of the method. Summary of Background Data. Few studies have provided technical guidelines for screw placement in patients with extremely small thoracic pedicles in scoliosis. Methods. In a severely rotated scoliotic spine, thoracic pedicle screw placement is challenging, and particularly more so for extremely small pedicles with a diameter less than 2 mm. The authors introduced a novel method of screw placement for these small pedicles: “medial margin targeting method.” The C-arm fluoroscope is rotated until a true PA image of the rotated vertebral body is acquired and both pedicle shadows are symmetrically visualized en face. In extremely small pedicles, pedicle shadows appear as long, slender ellipses or lines. An imaginary pedicle outline is presumed with the elliptical or linear shadows being the medial margin of the pedicle. The entry point of a screw can be made at the 10-oclock or 2-oclock position on the presumed pedicle outline, and the screw can be safely inserted targeting the presumed medial margin with caution not to penetrate the medial cortex using the guidance of a true PA image. This is a kind of extrapedicular screw placement method. The safety and accuracy of this method were evaluated in 97 patients with scoliosis who had undergone posterior correction and instrumentation using postoperative computed tomography scans. A total of 1634 pedicle screws were inserted into thoracic pedicles, 128 of them (7.8%) being extremely small pedicles with a diameter less than 2 mm. Results. Among 128 extremely small thoracic pedicles with a diameter less than 2 mm, one screw (0.8%) violated the medial cortex and 22 screws (17.6%) violated the anterior cortex of the vertebral body. No screws violated the lateral cortex of the pedicle-rib unit. There were no complications associated with screw misplacement. Conclusion. In scoliosis patients with extremely small thoracic pedicles, our pedicle screw placement method targeting the presumed medial margin in a true PA C-arm image allows easy application with accuracy and safety, which would not possible by any other method described so far.

Is it enough to stop distal fusion at L3 in adolescent idiopathic scoliosis with major thoracolumbar/lumbar curves?

PurposeThe choice of distal fusion level in adolescent idiopathic scoliosis (AIS) patients with major thoracolumbar or lumbar (TL/L) curves (Lenke type 3C, 5C, or 6C) remains debatable. One of the most controversial issues involves stopping the distal fusion at L3, which might result in an increased risk of decompensation but save more mobile spinal segments. The purpose of this study was to evaluate and compare the clinical and radiological outcomes of corrective surgery for AIS with major TL/L curves according to the distal fusion level.Methods229 AIS patients with Lenke type 3C, 5C, or 6C curves that underwent corrective surgery were included. Patients were grouped according to distal fusion level, either L3 (group A) or L4 (group B), and followed up for over 2xa0years. Group A was further divided into lower end vertebra (LEV) and last touching vertebra (LTV). The SRS-22 score was used to assess clinical outcomes. All radiological parameters were assessed pre- and postoperatively by standing anteroposterior whole-spine radiographs. Clinical and radiological parameters were compared between the groups.ResultsPostoperative decompensation was found in 4.6xa0% (9/197) of group A patients and 9.3xa0% (3/32) of group B patients. This difference was not statistically significant (Pxa0=xa00.258). No difference was found in the clinical and radiological parameters between the two groups either pre- or postoperatively. Subgroup analysis showed that the scoliosis correction rate and postoperative apical vertebral translation were lower in cases with an LEVxa0≤xa0L4 or LTVxa0=xa0L5 when the fusion stopped at L3 distally. The adjacent disc wedge angle was aggravated postoperatively in these cases, although this did not reach statistical significance.ConclusionsThere is no difference in the radiological and clinical outcomes in AIS according to the distal fusion level. Major TL/L curve correction in AIS may be sufficient distally at L3 in cases with an LEVxa0≥xa0L3 and LTVxa0≥xa0L4. However, stopping fusion at L3 requires caution in LEVxa0≤xa0L4 or LTVxa0=xa0L5 patients, as this correction rate might be suboptimal and causes a possible progression of the adjacent disc wedge angle.