Postoperative Changes of Spinopelvic Sagittal Parameters After Cervical Laminoplasty for Cervical Spondylotic Myelopathy.

STUDY DESIGN: A retrospective analysis of prospectively collected data. OBJECTIVE: To investigate postoperative changes of spinopelvic sagittal parameters after laminoplasty for cervical spondylotic myelopathy (CSM) accompanying postoperative cervical kyphotic deformity or cervical regional sagittal imbalance. SUMMARY OF BACKGROUND DATA: To the best of our knowledge, no study has been reported concerning postoperative changes of spinopelvic sagittal parameters accompanying postoperative deterioration of cervical sagittal alignment or balance after cervical laminoplasty. METHODS: Forty-five CSM patients without preoperative cervical kyphosis who underwent laminoplasty were included. None of the 45 patients had a medical history of previous spine surgery, hip joint surgery, or knee joint surgery. The patients were divided into 2 groups (kyphosis and lordosis groups) according to postoperative C2-7 angle, and they were also divided into 2 other groups (imbalance and balance groups) according to postoperative C1-7 sagittal vertical axis. Postoperative changes (Δ) of T1 slope (T1S), thoracic kyphosis, thoracolumbar kyphosis (TLK), lumbar lordosis (LL), Pelvic tilt, and C7 sagittal vertical axis were measured comparing lateral radiographs of the whole spine in the standing position taken at 1 year postoperatively with those before surgery. RESULTS: Both T1S and TLK significantly decreased after cervical laminoplasty in the kyphosis group compared with the lordosis group. On the other hand, both T1S and TLK increased significantly, and LL significantly decreased after surgery in the imbalance group compared with the balance group. CONCLUSIONS: At 1 year after laminoplasty for CSM, both T1S and TLK significantly decreased accompanying postoperative cervical kyphotic deformity as a compensatory action for postoperative cervical kyphosis to maintain the global sagittal balance of the spine, whereas both T1S and TLK increased significantly, and LL significantly decreased accompanying postoperative cervical reginal sagittal imbalance which resulted in postoperative forward inclination of the whole spine.

The Influence of Titanium-coated Poryetheretherketone Cages in Fusion Status after Posterior Lumbar Interbody Fusion with Cortical Bone Trajectory Screw Fixation.

OBJECTIVE: Posterior lumbar interbody fusion (PLIF) with cortical bone trajectory (CBT) screw fixation (CBT-PLIF) shows potential for reducing adjacent segmental disease. Previously, our investigations revealed a relatively lower fusion rate with the use of carbon fiber-reinforced polyetheretherketone (CP) cages in CBT-PLIF compared with traditional pedicle screw fixation (PS-PLIF) using CP cages. This study aims to evaluate whether the implementation of titanium-coated polyetheretherketone (TP) cages can enhance fusion outcomes in CBT-PLIF. METHODS: A retrospective analysis was conducted on 68 consecutive patients who underwent CBT-PLIF with TP cages (TP group) and 89 patients who underwent CBT-PLIF with CP cages (CP group). Fusion status was assessed using computed tomography at 1 year postoperatively and dynamic plain radiographs at 2 years postoperatively. RESULTS: No statistically significant differences in fusion rates were observed at 1 and 2 years postoperatively between the TP group (86.8% and 89.7%, respectively) and the CP group (77.5% and 88.8%, respectively). Notably, the CP group exhibited a significant improvement in fusion rate from 1 to 2 years postoperatively (P = 0.002), while no significant improvement was observed in the TP group. CONCLUSIONS: Examination of temporal changes in fusion rates reveals that only the TP group achieved a peak fusion rate 1 year postoperatively. This implies that TP cages may enhance the fusion process even after CBT-PLIF. Nevertheless, the definitive efficacy of TP cages for CBT-PLIF remains uncertain in the context of overall fusion rates.

Responsiveness of the Zurich Claudication Questionnaire, the Oswestry Disability Index, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, the 8-Item Short Form Health Survey, and the Euroqol 5 dimensions 5 level in the assessment of patients with lumbar spinal stenosis.

PURPOSE: To assess the responsiveness of the Zurich Claudication Questionnaire (ZCQ), the Oswestry Disability Index, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, the visual analog scale (VAS), the 8-Item Short Form Health Survey (SF-8), and the EuroQol 5 dimensions 5 level as methods of assessing outcomes of surgery for lumbar spinal stenosis. METHODS: We analyzed 218 patients who had undergone lumbar surgery for spinal stenosis and completed one year of follow-up. The internal responsiveness of each questionnaire and any domains was assessed by the effect size and standardized response mean. External responsiveness was assessed by the Spearman rank correlation coefficient and the receiver operating characteristics (ROC) curve. RESULTS: The most responsive assessments were "symptom severity" and "physical function" on the ZCQ, "walking ability" on the JOABPEQ, "leg pain" on the VAS, and "social function" on the JOABPEQ. The moderately responsive assessments were the physical component summary on the SF-8, the ODI, the EQ5D-5L, "low back pain" on the JOABPEQ, and "leg numbness" on the VAS. The least responsive assessments were "low back pain" on the VAS, "mental health" and "lumbar function" on the JOABPEQ, and the mental component summary on the SF-8. CONCLUSIONS: Because of its high responsiveness, "symptom severity" on the ZCQ is recommended as a primary tool for assessing outcome when designing prospective studies for lumbar spinal stenosis.

Early Fusion Status After Posterior Lumbar Interbody Fusion With Cortical Bone Trajectory Screw Fixation or Traditional Trajectory Screw Fixation: A Comparison Between the Titanium-coated Polyetheretherketone Cage and the Same Shape Polyetheretherketone Cage.

STUDY DESIGN: A retrospective analysis of prospectively collected data. OBJECTIVE: The aim was to examine whether posterior lumbar interbody fusion with cortical bone trajectory screw fixation (CBT-PLIF) is inferior to PLIF using traditional trajectory screw fixation (TT-PLIF) regarding early fusion status and whether the titanium-coated polyetheretherketone (PEEK) cage (TP cage) improves early fusion status compared with the same shape pure PEEK cage (P cage). SUMMARY OF BACKGROUND DATA: We recently reported that the fusion rate was relatively lower after CBT-PLIF than after TT-PLIF, although no significant difference was found and that compared with the carbon PEEK cage, the TP cage significantly reduced the incidence of vertebral endplate cysts (cyst signs) and slightly improved the early fusion rate at 1 year after CBT-PLIF. MATERIALS AND METHODS: The subjects were 37 patients undergoing TT-PLIF using P cages (TT-P group), 24 patients undergoing CBT-PLIF using P cages (CBT-P group), 32 patients undergoing TT-PLIF using TP cages (TT-TP group), and 20 patients undergoing CBT-PLIF using TP cages (CBT-TP group). On multiplanar reconstruction computed tomography at 6 months after surgery, cyst signs were evaluated and classified into diffuse or local cysts. Early fusion status was assessed using both dynamic plain radiographs and multiplanar reconstruction computed tomography at 1-year postoperatively. RESULTS: The incidence of the diffuse cyst was 27.0% in the TT-P group, 29.2% in the CBT-P group, 25.0% in the TT-TP group and 25.0% in the CBT-TP group (P>0.05). The early fusion rate was 75.7% in the TT-P group, 75.0% in the CBT-P group, 71.9% in the TT-TP group and 75.0% in the CBT-TP group (P>0.05). CONCLUSIONS: These results indicate that CBT-PLIF resulted in the equivalent early fusion status to TT-PLIF and that compared with the same shape P cage, the TP cage did not improve early fusion status after both TT-PLIF and CBT-PLIF.

Surgical outcomes after posterior lumbar interbody fusion using traditional trajectory screw fixation or cortical bone trajectory screw fixation: A comparative study between the polyetheretherketone cage and the same shape titanium-coated polyetheretherketone cage.

OBJECTIVE: To investigate whether or not the fusion rate after posterior lumbar interbody fusion with cortical bone trajectory screw fixation (CBT-PLIF) is lower than after PLIF using traditional trajectory screw fixation (TT-PLIF) and whether or not the titanium-coated polyetheretherketone (PEEK) cage (TiP cage) improves fusion status compared to the same shape uncoated PEEK cage (P cage). METHODS: The subjects were 37 patients undergoing TT-PLIF using P cages (P-TT group), 24 patients undergoing CBT-PLIF using P cages (P-CBT group), 32 patients undergoing TT-PLIF using TiP cages (TiP-TT group), and 20 patients undergoing CBT-PLIF using TiP cages (TiP-CBT group). All patients from the 4 groups underwent our unified PLIF procedure (total facetectomy, subtotal discectomy, and the same bone graft technique using the same shape cages) except for the screw trajectories and the surface materials of the cages. Clinical symptoms were assessed using the Japanese Orthopedic Association (JOA) score before surgery and at 2-year postoperatively. None of age at the time of surgery, gender, fused segment and preoperative JOA score showed significant differences among the 4 groups. On multiplanar reconstruction computed tomography (MPR-CT) at 6months after surgery, vertebral end plate cysts were evaluated and classified into local or diffuse cysts. Fusion status was assessed using both dynamic plain radiographs and MPR-CT at postoperative 2-year. RESULTS: Neither the mean JOA score nor the mean recovery rate of the JOA score at 2-year after surgery showed significant differences among the 4 groups. The incidence of the diffuse cyst (a known predictor of non-union) was 27.0% in the P-TT group, 29.2% in the P-CBT group, 25.0% in the TiP-TT group and 25.0% in the TiP-CBT group (P > 0.05). The fusion rate was 89.2% in the P-TT group, 91.7% in the P-CBT group, 90.6% in the TiP-TT group and 90.0% in the TiP-CBT group (P > 0.05). CONCLUSIONS: After our unified PLIF procedure except for the screw trajectories and the surface materials of the cages, CBT-PLIF resulted in the equivalent fusion rate to TT-PLIF and the TiP cage did not lead to the improved fusion rate compared to the same shape P cage.

Impacts of postoperative changes of segmental mobility on neurological improvement after laminoplasty for cervical ossification of the posterior longitudinal ligament.

ABSTRACT: Several studies have demonstrated that the dynamic factor at the mobile segment affects the severity of myelopathy in patients with cervical ossification of the posterior longitudinal ligament (C-OPLL), and posterior decompression supplemented with posterior instrumented fusion at the mobile segment provides good neurological improvement. However, there have been few reports of changes in range of motion at the mobile segment (segmental ROM) after laminoplasty (LP). The aim of this study was thus to retrospectively investigate changes in segmental ROM after LP and the impacts of these changes on neurological improvement in patients with C-OPLL.A total of 51 consecutive patients who underwent LP for C-OPLL since May 2010 and were followed for at least 2 years after surgery were included in this study. Neurological status was assessed using the Japanese Orthopaedic Association (JOA) score before surgery and at 2-year follow-up. Segmental ROM at the responsible level for myelopathy was measured preoperatively and at 2-year follow-up using lateral flexion-extension radiographs of the cervical spine.The mean JOA score improved significantly from 10.7 points preoperatively to 13.5 points at 2 years after surgery (mean recovery rate, 45.0%). The mean segmental ROM decreased significantly from 6.5 degrees before surgery to 3.2 degrees at 2 years after surgery. In the good clinical outcome group (recovery rate of the JOA score ≥50%; n = 22), the mean segmental ROM decreased significantly from 5.8 degrees preoperatively to 3.0 degrees postoperatively. It also decreased significantly from 7.1 degrees to 3.4 degrees in the poor clinical outcome group (recovery rate of the JOA score <50%; n = 29).This study showed that segmental ROM was stabilized after LP in most patients with C-OPLL. Neither preoperative nor postoperative segmental ROM showed significant differences between the good and poor clinical outcome groups and neither a postoperative increase nor decrease of segmental ROM significantly affected the recovery rate of the JOA score.

Epidemiology of symptomatic ossification of the posterior longitudinal ligament: a nationwide registry survey.

BACKGROUND: Ossification of the posterior longitudinal ligament (OPLL) is radiographically detectable in 3-6% of Asian individuals, although not all detectable OPLL cases lead to myelopathy. To date, it is unknown how many patients suffer from neurological symptoms due to OPLL. The purpose of this study was to investigate the epidemiology of symptomatic OPLL using Japan's national registry database. METHODS: We examined the registry data of patients with OPLL who held a certificate of medical subsidy from the Japanese Ministry of Health, Labor and Welfare. The study period was from January 1, 2011 to December 31, 2012. RESULTS: Registry data revealed that the incidence and the period prevalence of symptomatic OPLL were 0.005% (5 per 100,000 population) and 0.027% (27 per 100,000 population), respectively. OPLL occurred twice as often in men as in women. The peak age for onset of symptoms was 60-69 years. The mean Japanese Orthopedic Association (JOA) score was 9 points. Ninety percent of OPLL patients underwent surgery, and 90% of these surgeries were performed with a posterior approach. The most common indication for surgery was a JOA score of 11 points. CONCLUSIONS: According to registry data, the prevalence of symptomatic OPLL was less than one-hundredth of that of radiographically detected OPLL. This indicates that most cases of radiographically detectable OPLL may be asymptomatic.

Does Atherosclerosis Have Negative Impacts on Early Adjacent Segment Degeneration After Posterior Lumbar Interbody Fusion?

STUDY DESIGN: Retrospective study. OBJECTIVE: To examine whether atherosclerosis has negative impacts on early adjacent segment degeneration (ASD) after posterior lumbar interbody fusion using traditional trajectory pedicle screw fixation (TT-PLIF). METHODS: The subjects were 77 patients who underwent single-level TT-PLIF for degenerative lumbar spondylolisthesis. Using dynamic lateral radiographs of the lumbar spine before surgery and at 3 years postoperatively, early radiological ASD (R-ASD) was examined. Early symptomatic ASD (S-ASD) was diagnosed when neurologic symptoms deteriorated during postoperative 3-year follow-up and the responsible lesions adjacent to the fused segment were also confirmed on magnetic resonance imaging. According to the scoring system by Kauppila et al, the abdominal aortic calcification score (AAC score: a surrogate marker of systemic atherosclerosis) was assessed using preoperative lateral radiographs of the lumbar spine. RESULTS: The incidence of early R-ASD was 41.6% at the suprajacent segment and 8.3% at the subjacent segment, respectively. Patients with R-ASD had significantly higher AAC score than those without R-ASD. The incidence of early S-ASD was 3.9% at the suprajacent segment and 1.4% at the subjacent segment, respectively. Patients with S-ASD had higher AAC score than those without S-ASD, although there was no significant difference. CONCLUSIONS: At 3 years after surgery, the advanced AAC had significantly negative impacts on early R-ASD after TT-PLIF. This result indicates that impaired blood flow due to atherosclerosis can aggravate degenerative changes at the adjacent segments of the lumbar spine after PLIF.

Postoperative Loss of Lumbar Lordosis Affects Clinical Outcomes in Patients with Pseudoarthrosis after Posterior Lumbar Interbody Fusion Using Cortical Bone Trajectory Screw Fixation.

STUDY DESIGN: Retrospective cohort study. PURPOSE: This study aimed to investigate relationships between clinical outcomes and radiographic parameters in patients with pseudoarthrosis after posterior lumbar interbody fusion (PLIF). OVERVIEW OF LITERATURE: In some patients with pseudoarthrosis after PLIF, clinical symptoms improve following surgery, although pseudoarthrosis can often be one of the complications. However, there are no previous reports describing differences between patients with pseudoarthrosis after PLIF who have obtained better clinical outcomes and those who have not. METHODS: Twenty-seven patients who were diagnosed with pseudoarthrosis after single-level PLIF with cortical bone trajectory screw fixation (CBT-PLIF) were enrolled in this study. They were divided into two groups based on mean improvement of 22 points on the Oswestry Disability Index (ODI) at the 2-year follow-up. Group G consisted of 15 patients who showed improvement on the ODI of ≥22 points, and group P consisted of the residual 12 patients. Radiographic parameters, percentage of slip, lumbar lordosis (LL), segmental lordosis, segmental range of motion, screw loosening, and subsidence were compared between the two groups. RESULTS: There were no significant differences between the two groups on radiographic parameters except for postoperative changes in LL. Although surgery-induced changes in LL showed no significant difference between the two groups, changes in LL from before surgery to 2-year follow-up and during postoperative 2-year follow-up were significantly better in group G (mean change of LL: +3.5° and +5.1°, respectively) compared to group P (mean change of LL: -4.6° and -0.5°, respectively) (p<0.01 and 0.05, respectively). CONCLUSIONS: Patients with greater improvement in ODI gained LL over the 2-year follow-up, whereas patients with less improvement in ODI lost LL during the 2-year follow-up. These results indicate that there is a significant correlation between clinical outcomes and LL even in patients with pseudoarthrosis after single-level CBT-PLIF.

Two-level Posterior Lumbar Interbody Fusion at the Lumbosacral Segment has a High Risk of Pseudarthrosis and Poor Clinical Outcomes: Comparison Between the Lumbar and Lumbosacral Segments.

STUDY DESIGN: This was a retrospective study. OBJECTIVES: The purposes of this study were to investigate the fusion rate and clinical outcomes of 2-level posterior lumbar interbody fusion (PLIF). SUMMARY OF BACKGROUND DATA: PLIF provides favorable clinical outcomes and a high fusion rate. However, most extant studies have been limited to the results of single-level PLIF. Clinical outcomes and fusion rate of 2-level PLIF are unknown. MATERIALS AND METHODS: In total, 73 patients who underwent 2-level PLIF below L3 between 2008 and 2016 (follow-up period >2 y) were included. Patients were divided into the 2 groups on the basis of surgical level. The lumbar group included 48 patients who underwent L3/4/5 PLIF, and the lumbosacral group included 25 patients who underwent L4/5/S PLIF. Fusion rate and clinical outcomes were compared. The Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and a visual analog scale were used for evaluation. RESULTS: Fusion rate was significantly lower in the lumbosacral group (lumbar 96% vs. lumbosacral 64%; P<0.001). Eight of 9 cases of pseudarthrosis occurred at the lumbosacral segment. Improvement in the mental health domain of the JOAPEQ was significantly lower in the lumbosacral group (lumbar 16 vs. lumbosacral 10; P=0.02). The VAS data showed that improvements in the following variables were significantly lower in the lumbosacral group than in the lumbar group: pain in low back (lumbar -38 vs. lumbosacral -23; P=0.004), pain in buttocks or lower leg (lumbar -48 vs. lumbosacral -29; P=0.04), and numbness in buttocks or lower leg (lumbar -44 vs. lumbosacral -33; P=0.04). CONCLUSIONS: Two-level PLIF at the lumbosacral segment demonstrated a significantly lower fusion rate and poorer clinical outcomes than that at the lumbar-only segments. Some reinforcement for the sacral anchor is recommended to improve fusion rate, even for short fusion like 2-level PLIF, if the lumbosacral segment is included. LEVEL OF EVIDENCE: Level III.

Early cephalad adjacent segment degeneration after posterior lumbar interbody fusion: a comparative study between cortical bone trajectory screw fixation and traditional trajectory screw fixation.

OBJECTIVE: Cortical bone trajectory (CBT) screw insertion through a caudomedial starting point provides advantages in limiting dissection of the superior facet joints and reducing muscle dissection and the risk of superior-segment facet violation by the screw. These advantages of the cephalad CBT screw can result in lower rates of early cephalad adjacent segment degeneration (ASD) after posterior lumbar interbody fusion (PLIF) with CBT screw fixation (CBT-PLIF) than those after PLIF using traditional trajectory screw fixation (TT-PLIF). Here, the authors investigated early cephalad ASD after CBT-PLIF and compared these results with those after TT-PLIF. METHODS: The medical records of all patients who had undergone single-level CBT-PLIF or single-level TT-PLIF for degenerative lumbar spondylolisthesis (DLS) and with at least 3 years of postsurgical follow-up were retrospectively reviewed. At 3 years postoperatively, early cephalad radiological ASD changes (R-ASD) such as narrowing of disc height (> 3 mm), anterior or posterior slippage (> 3 mm), and posterior opening (> 5°) were examined using lateral radiographs of the lumbar spine. Early cephalad symptomatic adjacent segment disease (S-ASD) was diagnosed when clinical symptoms such as leg pain deteriorated during postoperative follow-up and the responsible lesion suprajacent to the fused segment was confirmed on MRI. RESULTS: One hundred two patients underwent single-level CBT-PLIF for DLS and were followed up for at least 3 years (CBT group). As a control group, age- and sex-matched patients (77) underwent single-level TT-PLIF for DLS and were followed up for at least 3 years (TT group). The total incidence of early cephalad R-ASD was 12.7% in the CBT group and 41.6% in the TT group (p < 0.0001). The incidence of narrowing of disc height, anterior slippage, and posterior slippage was significantly lower in the CBT group (5.9%, 2.0%, and 4.9%) than in the TT group (16.9%, 13.0%, and 14.3%; p < 0.05). Early cephalad S-ASD developed in 1 patient (1.0%) in the CBT group and 3 patients (3.9%) in the TT group; although the incidence was lower in the CBT group than in the TT group, no significant difference was found between the two groups. CONCLUSIONS: CBT-PLIF, as compared with TT-PLIF, significantly reduced the incidence of early cephalad R-ASD. One of the main reasons may be that cephalad CBT screws reduced the risk of proximal facet violation by the screw, which reportedly can increase biomechanical stress and lead to destabilization at the suprajacent segment to the fused segment.

Abdominal Aortic Calcification Is a Significant Poor Prognostic Factor for Clinical Outcomes After Decompressive Laminotomy for Lumbar Spinal Canal Stenosis.

STUDY DESIGN: Retrospective study. OBJECTIVE: To examine whether the presence of chronic kidney disease (CKD) or advanced abdominal aortic calcification (AAC) negatively affects clinical outcomes after decompression surgery for lumbar spinal canal stenosis (LSCS). METHODS: The subjects comprised 143 patients who underwent decompressive laminotomy for LSCS and were followed for ≥2 years. Fifty-five patients had CKD (Stage 3-4). Clinical outcome was assessed using the Japanese Orthopaedic Association (JOA) score before surgery and at 2-year postoperatively. According to the scoring system by Kauppila et al, the AAC score (a surrogate marker of systemic atherosclerosis) was assessed using preoperative lateral radiographs of the lumbar spine. RESULTS: Patient age had weak but significantly negative correlations with both the preoperative JOA score and the JOA score at 2 years after surgery, but did not have a significant correlation with the recovery rate of the JOA score at 2 years postoperatively. The JOA score before surgery, the JOA score at 2-year follow-up, and the recovery rate of the JOA score were slightly lower in the CKD patients than in those without CKD, although there were no significant differences between the 2 groups. On the contrary, the AAC score had a weak but significantly negative correlation with the preoperative JOA score, and had relatively strong and significantly negative correlations with both the JOA score at 2 years after surgery and the recovery rate of the JOA score. CONCLUSIONS: At 2 years after surgery, advanced AAC was a significant poor prognostic factor for clinical outcomes of decompression surgery for LSCS.

Differences in Postoperative Changes of Cervical Sagittal Alignment and Balance After Laminoplasty Between Cervical Spondylotic Myelopathy and Cervical Ossification of the Posterior Longitudinal Ligament.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To compare postoperative changes of cervical sagittal alignment (CSA) and cervical sagittal balance (CSB) after laminoplasty between cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL) and to examine impacts of these radiologic changes on neurologic outcomes. METHODS: A total of 168 consecutive patients with CSM (CSM group) and 51 consecutive patients with OPLL (OPLL group) were included. As indicators of CSA and CSB, the C2-7 angle and C1-C7 sagittal vertical axis (SVA) were, respectively, measured before surgery and at 2-year follow-up. Neurologic status was assessed using the Japanese Orthopaedic Association score before surgery and at 2-year follow-up. RESULTS: Whereas both postoperative loss of C2-7 angle and increase of C1-C7 SVA were significantly greater in the elderly subgroup of the CSM group, patient age did not significantly affect these changes in the OPLL group. Preservation of C7 maintained C1-C7 SVA at postoperative 2 years only in the CSM group. Postoperative cervical kyphosis and sagittal imbalance significantly decreased neurologic improvement in the CSM group but not in the OPLL group. CONCLUSIONS: Elderly patients with CSM have significantly greater postoperative loss of lordosis and increase in C1-C7 SVA than nonelderly patients, and both postoperative kyphotic deformity and sagittal imbalance significantly deteriorate neurologic recovery. On the other hand, although patients with OPLL, irrespective of patient age and preservation of C7, have significantly more loss of lordosis and increase in C1-C7 SVA than CSM patients, neither postoperative kyphotic deformity nor sagittal imbalance significantly deteriorates neurologic recovery in OPLL patients.

Early Fusion Status after Posterior Lumbar Interbody Fusion with Cortical Bone Trajectory Screw Fixation: A Comparison of Titanium-Coated Polyetheretherketone Cages and Carbon Polyetheretherketone Cages.

STUDY DESIGN: Retrospective cohort study. PURPOSE: We recently reported that when compared to posterior lumbar interbody fusion (PLIF) using traditional pedicle screw fixation, PLIF with cortical bone trajectory screw fixation (CBT-PLIF) provided favorable clinical outcomes and reduced the incidence of symptomatic adjacent segment pathology, but resulted in relatively lower fusion rates. Since titanium-coated polyetheretherketone (PEEK) cages (TP) could improve and accelerate fusion status after CBT-PLIF, early fusion status was compared between CBT-PLIF using TP and carbon PEEK cages (CP). OVERVIEW OF LITERATURE: A systematic review demonstrated that clinical studies at this early stage show similar fusion rates for TP compared to PEEK cages. METHODS: We studied 36 consecutive patients undergoing CBT-PLIF with TP (TP group) and 92 undergoing CBT-PLIF with CP (CP group). On multiplanar reconstruction computed tomography (MPR-CT) at 6 months postoperatively, vertebral endplate cysts (cyst signs) were evaluated and classified as diffuse or local cysts. Early fusion status was assessed by dynamic plain radiographs and MPR-CT at 1 year postoperatively. RESULTS: The incidences of cyst signs, diffuse cysts, and early fusion rate in the TP and CP groups were 38.9% and 66.3% (p<0.01), 16.7% and 32.6% (p=0.07), and 83.3% and 79.3% (p>0.05), respectively. Combining the two groups, 22 of 36 patients with diffuse cysts had nonunion at 1-year follow-up, compared to only three of 92 patients with local cysts or without cyst signs (p<0.01). CONCLUSIONS: Despite having fewer patients with endplate cysts at 6 months (a known risk factor for nonunion), the TP group had the same fusion rate as the CP group at 1-year follow-up. Thus, TP did not accelerate the fusion process after CBT-PLIF.

Cortical bone trajectory screw fixation versus traditional pedicle screw fixation for 2-level posterior lumbar interbody fusion: comparison of surgical outcomes for 2-level degenerative lumbar spondylolisthesis.

OBJECTIVE The cortical bone trajectory (CBT) screw technique is a new nontraditional pedicle screw (PS) insertion method. However, the biomechanical behavior of multilevel CBT screw/rod fixation remains unclear, and surgical outcomes in patients after 2-level posterior lumbar interbody fusion (PLIF) using CBT screw fixation have not been reported. Thus, the purposes of this study were to examine the clinical and radiological outcomes after 2-level PLIF using CBT screw fixation for 2-level degenerative lumbar spondylolisthesis (DS) and to compare these outcomes with those after 2-level PLIF using traditional PS fixation. METHODS The study included 22 consecutively treated patients who underwent 2-level PLIF with CBT screw fixation for 2-level DS (CBT group, mean follow-up 39 months) and a historical control group of 20 consecutively treated patients who underwent 2-level PLIF using traditional PS fixation for 2-level DS (PS group, mean follow-up 35 months). Clinical symptoms were evaluated using the Japanese Orthopaedic Association (JOA) scoring system. Bony union was assessed by dynamic plain radiographs and CT images. Surgery-related complications, including symptomatic adjacent-segment disease (ASD), were examined. RESULTS The mean operative duration and intraoperative blood loss were 192 minutes and 495 ml in the CBT group and 218 minutes and 612 ml in the PS group, respectively (p < 0.05 and p > 0.05, respectively). The mean JOA score improved significantly from 12.3 points before surgery to 21.1 points (mean recovery rate 54.4%) at the latest follow-up in the CBT group and from 12.8 points before surgery to 20.4 points (mean recovery rate 51.8%) at the latest follow-up in the PS group (p > 0.05). Solid bony union was achieved at 90.9% of segments in the CBT group and 95.0% of segments in the PS group (p > 0.05). Symptomatic ASD developed in 2 patients in the CBT group (9.1%) and 4 patients in the PS group (20.0%, p > 0.05). CONCLUSIONS Two-level PLIF with CBT screw fixation for 2-level DS could be less invasive and result in improvement of clinical symptoms equal to those of 2-level PLIF using traditional PS fixation. The incidence of symptomatic ASD and the rate of bony union were lower in the CBT group than in the PS group, although these differences were not significant.

Fixation Strength of Caudal Pedicle Screws after Posterior Lumbar Interbody Fusion with the Modified Cortical Bone Trajectory Screw Method.

STUDY DESIGN: Clinical case series. PURPOSE: In the posterior lumbar interbody fusion (PLIF) procedure in our institute, the cephalad screw trajectory follows a mediolateral and caudocephalad directed path according to the original cortical bone trajectory (CBT) method. However, the starting point of the caudal screw is at the medial border of the pedicle on an articular surface of the superior articular process, and the trajectory takes a mediolateral path parallel to the cephalad endplate. The incidence of caudal screw loosening after PLIF with this modified CBT screw method was investigated, and significant risk factors for caudal screw loosening were evaluated. OVERVIEW OF LITERATURE: A biomechanical study of this modified caudal screw trajectory using the finite element method reported about a 20% increase in uniaxial yield pullout load compared with the traditional trajectory. However, there has been no clinical study concerning the fixation strength of this modified caudal screw trajectory. METHODS: The subjects were 193 consecutive patients who underwent single-level PLIF with modified CBT screw fixation. Caudal screw loosening was checked in computed tomography at 6 months after surgery, and screw loosening was defined as a radiolucency of 1 mm or more at the bone-screw interface. RESULTS: The incidence of caudal screw loosening after lumbosacral PLIF (46.2%) was significantly higher than that after floating PLIF (6.0%). No significant differences in sex, brand of the instruments, and diameter and length of the caudal screw were evident between patients with and without caudal screw loosening. Patients with caudal screw loosening were significantly older at the time of surgery than patients without caudal screw loosening. CONCLUSIONS: Fixation strength of the caudal screw after floating PLIF with this modified CBT screw technique was sufficiently acceptable. Fixation strength after the lumbosacral procedure was not.

Surgical outcomes after laminoplasty for cervical spondylotic myelopathy in patients with renal dysfunction and/or aortic arch calcification.

OBJECTIVE The authors recently reported that the presence of chronic kidney disease (CKD) and/or extended abdominal aortic calcification was associated with significantly worse clinical outcomes after posterior lumbar interbody fusion. CKD is one of the highest risk factors for systemic atherosclerosis. Therefore, impaired blood flow due to atherosclerosis could exacerbate degeneration of the cervical spine and neural tissue. However, there has been no report of a study evaluating the deleterious effects of CKD and atherosclerosis on the outcomes after decompression surgery for cervical compression myelopathy. The purpose of this study was thus to examine whether CKD and systemic atherosclerosis affect surgical outcomes after laminoplasty for cervical spondylotic myelopathy (CSM). METHODS The authors analyzed data from 127 consecutive cases involving patients who underwent laminoplasty for CSM and met their inclusion criteria. Stage 3-4 CKD was present as a preoperative comorbidity in 44 cases. Clinical status was assessed using the Japanese Orthopaedic Association (JOA) cervical myelopathy evaluation questionnaire before surgery and 2 years postoperatively. As a marker of systemic atherosclerosis, the presence of aortic arch calcification (AoAC) was assessed on preoperative chest radiographs. RESULTS AoAC was found on preoperative chest radiographs in 40 of 127 patients. Neither CKD nor AoAC had a statistically significant deleterious effect on preoperative JOA score. However, CKD and AoAC were significantly associated with reductions in both the JOA score recovery rate (mean 36.1% in patients with CKD vs 44.7% in those without CKD; 26.0% in patients with AoAC vs 48.9% in those without AoAC) and the change in JOA score at 2 years after surgery (mean 2.3 points in patients with CKD vs 3.1 points in those without CKD; 2.1 points for patients with AoAC vs 3.2 points for those without AoAC). A multivariate regression analysis showed that AoAC was a significant independent predictor of poor outcome with respect to both for the difference between follow-up and preoperative JOA scores and the JOA score recovery rate. CONCLUSIONS CKD and AoAC were associated with increased rates of poor neurological outcomes after laminoplasty for CSM, and AoAC was a significant independent predictive factor for poor outcome.

Posterior lumbar interbody fusion with cortical bone trajectory screw fixation versus posterior lumbar interbody fusion using traditional pedicle screw fixation for degenerative lumbar spondylolisthesis: a comparative study.

OBJECTIVE Several biomechanical studies have demonstrated the favorable mechanical properties of the cortical bone trajectory (CBT) screw. However, no reports have examined surgical outcomes of posterior lumbar interbody fusion (PLIF) with CBT screw fixation for degenerative spondylolisthesis (DS) compared with those after PLIF using traditional pedicle screw (PS) fixation. The purposes of this study were thus to elucidate surgical outcomes after PLIF with CBT screw fixation for DS and to compare these results with those after PLIF using traditional PS fixation. METHODS Ninety-five consecutive patients underwent PLIF with CBT screw fixation for DS (CBT group; mean followup 35 months). A historical control group consisted of 82 consecutive patients who underwent PLIF with traditional PS fixation (PS group; mean follow-up 40 months). Clinical status was assessed using the Japanese Orthopaedic Association (JOA) scale score. Fusion status was assessed by dynamic plain radiographs and CT. The need for additional surgery and surgery-related complications was also evaluated. RESULTS The mean JOA score improved significantly from 13.7 points before surgery to 23.3 points at the latest follow-up in the CBT group (mean recovery rate 64.4%), compared with 14.4 points preoperatively to 22.7 points at final follow-up in the PS group (mean recovery rate 55.8%; p < 0.05). Solid spinal fusion was achieved in 84 patients from the CBT group (88.4%) and in 79 patients from the PS group (96.3%, p > 0.05). Symptomatic adjacent-segment disease developed in 3 patients from the CBT group (3.2%) compared with 9 patients from the PS group (11.0%, p < 0.05). CONCLUSIONS PLIF with CBT screw fixation for DS provided comparable improvement of clinical symptoms with PLIF using traditional PS fixation. However, the successful fusion rate tended to be lower in the CBT group than in the PS group, although the difference was not statistically significant between the 2 groups.

Lifestyle-Related Diseases Affect Surgical Outcomes after Posterior Lumbar Interbody Fusion.

Study Design Retrospective study. Objective Hyperlipidemia (HL) and hypertension (HT) lead to systemic atherosclerosis. Not only atherosclerosis but also bone fragility and/or low bone mineral density result from diabetes mellitus (DM) and chronic kidney disease (CKD). The purpose of this study was to examine whether these lifestyle-related diseases affected surgical outcomes after posterior lumbar interbody fusion (PLIF). Methods The subjects comprised 122 consecutive patients who underwent single-level PLIF for degenerative lumbar spinal disorders. The clinical results were assessed using the Japanese Orthopaedic Association (JOA) score before surgery and at 2 years postoperatively. The fusion status was graded as union in situ, collapsed union, or nonunion at 2 years after surgery. The abdominal aorta calcification (AAC) score was assessed using preoperative lateral radiographs of the lumbar spine. Results HL did not significantly affect the JOA score recovery rate. On the other hand, HT and CKD (stage 3 to 4) had a significant adverse effect on the recovery rate. The recovery rate was also lower in the DM group than in the non-DM group, but the difference was not significant. The AAC score was negatively correlated with the JOA score recovery rate. The fusion status was not significantly affected by HL, HT, DM, or CKD; however, the AAC score was significantly higher in the collapsed union and nonunion group than in the union in situ group. Conclusions At 2 years after PLIF, the presence of HT, CKD, and AAC was associated with significantly worse clinical outcomes, and advanced AAC significantly affected fusion status.

Incidence and Risk Factors for Late Neurologic Deterioration after C3-C6 Laminoplasty for Cervical Spondylotic Myelopathy.

Study Design Retrospective study. Objective We previously reported that the long-term neurologic outcomes of C3-C6 laminoplasty for cervical spondylotic myelopathy (CSM) are satisfactory, with reduced frequencies of postoperative axial neck pain and kyphotic deformity. However, only 20 patients were included, which is a limitation in that study. The present study investigated the incidence of late neurologic deterioration (LND) of myelopathic symptoms after C3-C6 laminoplasty for CSM and attempted to identify significant risk factors for LND in a larger patient population. Methods Subjects comprised 137 consecutive patients with CSM who underwent C3-C6 laminoplasty (bilateral open-door laminoplasty, n = 85; unilateral open-door laminoplasty, n = 52) and were followed for >24 months (mean follow-up, 70 months; range, 25 to 124 months). The patients' medical records were examined for evidence of LND due to cervical myelopathy. The age at time of surgery, sex, surgical procedures, anteroposterior spinal canal diameter at the C7 level, type of C6 spinous process, pre- and postoperative C2-C7 angle, C3-C6 range of motion (ROM), and disk height at the C6-C7 level were analyzed to identify risk factors for LND. Results Three patients (2.2%) developed LND of myelopathic symptoms due to caudal segment pathology adjacent to the C3-C6 laminoplasty (LND group). In these three patients, mean Japanese Orthopaedic Association (JOA) score improved from 10.2 before surgery to 12.2 at the time of maximum recovery, and declined to 9.7 just before additional surgery. On the other hand, in 134 patients without LND (non-LND group), the mean JOA score significantly improved from 10.2 before surgery to 13.4 at the time of maximum recovery and was maintained by the final follow-up (13.2). Compared with the non-LND group, the LND group showed significantly smaller anteroposterior spinal canal diameter at C7, more restricted postoperative C3-C6 ROM, and greater postoperative decrease in disk height at C6-C7, although a logistic regression analysis showed no significant differences. Conclusions In patients with CSM with more severe developmental spinal canal stenosis at C7, accelerated degeneration at the caudal segment resulting from restricted C3-C6 ROM after C3-C6 laminoplasty might lead to LND.