Importance of computed tomography Hounsfield units in predicting S1 screw loosening after lumbosacral fusion.

We investigated whether computed tomography (CT) Hounsfield unit (HU) values of the S1 screw trajectory can predict screw loosening after lumbosacral fixation. We analysed 102 patients (58 men and 44 women) who underwent L5-S1 interbody fusion between April 2018 and October 2019. We reviewed the characteristics of patients including body mass index, smoking, comorbidity with diabetes mellitus, and interbody fusion types. Bone mineral density (BMD) was obtained from the lumbar spine and total hip using dual-energy X-ray absorptiometry. Additionally, we reviewed the S1 screw lengths and diameters. HU values of both L1 vertebral bodies and bilateral S1 screw trajectories were measured on preoperative CT. At six months postoperatively, S1 screws on CT were assessed. Screws with a 1 mm or more radiolucent zone were defined as "loosening". Seventeen patients had loosened screws, and 85 patients did not. The patient characteristics did not significantly differ between the two groups. Both total hip BMD and L1 HU values were low in the loosening patient group (both p = 0.03). Of the 204 total S1 screws, 25 screws were loosened, and 179 screws were not. The screw length was short (p = 0.01), and the HU value of the S1 screw trajectory was low (p < 0.001) in the loosening screw group. Based on receiver operating characteristic analyses of these factors, the area under the curve of HU value of the S1 screw trajectory was the highest (0.79). Measuring the HU value of both the L1 vertebral body and S1 screw trajectory aids in predicting screw loosening.

Predictive biomarkers of ossification progression and bone metabolism dynamics in patients with cervical ossification of the posterior longitudinal ligament.

PURPOSE: This study aimed to establish biomarkers to predict the progression of ossification by examining ossification volume and bone metabolism dynamics in patients with ossification of the posterior longitudinal ligament (OPLL). METHODS: We assessed OPLL progression using computed tomography-based three-dimensional (3D) image analysis and examined bone metabolism dynamics in 107 patients with OPLL (men, 72; women, 35; mean age, 63.6 years). The volume of OPLL was calculated twice during the follow-up period, and OPLL progression was evaluated by the annual rate of ossification increase. Bone metabolism dynamics were assessed by routine blood tests and analysis of various serum biomarkers (including 25-hydroxyvitamin D, intact parathyroid hormone, fibroblast growth factor 23, intact N-terminal propeptide of type 1, tartrate-resistant acid phosphatase isoform 5b, sclerostin, and Dickkopf-1) and bone mineral density (BMD). Patients were classified into the progression (P) or non-progression (NP) group according to the annual rate of increase in previous 3D image analyses, and associated factors between these groups were compared. RESULTS: The P and NP groups consisted of 29 patients (23 men and 6 women) and 78 patients (49 men and 29 women), respectively. Univariate analysis revealed significant differences in terms of age, body mass index, serum phosphorus, serum sclerostin, and BMD. In multivariate analysis, age, serum phosphorus, and serum sclerostin were identified as independent factors associated with OPLL progression. CONCLUSION: Younger age, hypophosphatemia, and high serum sclerostin are risk factors for OPLL progression. Serum phosphorus and sclerostin could serve as important biomarkers for predicting ossification progression.

Effect of adjuvant therapy with teriparatide in patients with thoracolumbar osteoporotic vertebral fractures who underwent vertebroplasty with posterior spinal fusion.

Teriparatide (TPTD) administration has a potent osteogenic action and promotes the healing of osteoporotic vertebral fractures (OVFs). We aimed to investigate the outcomes of vertebroplasty with posterior spinal fusion (VP + PSF) and determine the impact of perioperative TPTD administration. We included 73 patients (18 male and 55 female patients; mean age: 78 years) with thoracolumbar OVFs who underwent VP + PSF and were followed-up for at least 2 years. Twenty-three patients who received TPTD perioperatively for > 3 months were included in the TPTD group, and the remaining 50 patients were included in the non-TPTD group. Radiographic findings regarding sagittal alignment and clinical outcomes in both groups were compared. The mean duration of TPTD administration was 17.5 ± 5.0 months (range 4-24 months). The mean loss of correction of local kyphosis angle in the TPTD group (4.0°) was lesser than that in the non-TPTD group (7.5°; p < 0.05); however, no significant differences were observed between the groups regarding global sagittal alignment, the occurrence of subsequent vertebral fractures, pedicle screw loosening and treatment-efficacy rates of clinical outcomes. Local kyphosis correction in patients who underwent VP + PSF for OVFs could be maintained through perioperative TPTD administration; however, TPTD administration had little effect on clinical outcomes.

Detailed features and prognostic factors of twenty-three patients with drop finger caused by cervical radiculopathy: a retrospective multicentre study.

PURPOSE: It has been reported that C7 and C8 nerve root impairment can cause drop finger; however, the clinical characteristics of each injured nerve root and post-operative outcomes remain unclear. This study aimed to investigate the detailed features and surgery-related prognostic factors of drop finger caused by cervical radiculopathy. METHODS: We retrospectively investigated the clinical characteristics, paralysis patterns and surgery-related prognostic factors of 23 patients with drop finger caused by cervical radiculopathy who underwent posterior cervical foraminotomy. We classified paralysis into three patterns based on the fingers predominantly exhibiting extensor digitorum communis (EDC) muscle weakness: index finger side-dominant, middle and ring fingers-dominant and little finger side-dominant. RESULTS: The aetiologies were cervical disc hernia (CDH) in ten patients, cervical spondylotic radiculopathy (CSR) in eight and both CDH and CSR in five. The levels of the decompressed root were C7 in one patient, C8 in 11 and both C7 and C8 in 11. Scapular pain was frequently observed as the initial symptom (78%), especially in patients with only C8 nerve root disorder (91%). Drop finger recovered to a score of ≥ 3 on manual muscle testing in 17 patients; patients with the little finger side-dominant pattern tended to have poor recoveries. Patients with CDH improved significantly than those with CSR or both CDH and CSR (p < 0.05). CONCLUSIONS: Good surgical recovery of drop finger can be expected in patients with CDH and in those with index fingers-dominant and middle and ring fingers-dominant patterns.

The Influence of Additives on the Interfacial Width and Line Edge Roughness in Block Copolymer Lithography.

The challenges of patterning next generation integrated circuits have driven the semiconductor industry to look outside of traditional lithographic methods in order to continue cost effective size scaling. The directed self-assembly (DSA) of block copolymers (BCPs) is a nanofabrication technique used to reduce the periodicity of patterns prepared with traditional optical methods. BCPs with large interaction parameters (χ eff), provide access to smaller pitches and reduced interface widths. Larger χ eff is also expected to be correlated with reduced line edge roughness (LER), a critical performance parameter in integrated circuits. One approach to increasing χ eff is blending the BCP with a phase selective additive, such as an Ionic liquid (IL). The IL does not impact the etching rates of either phase, and this enables a direct interrogation of whether the change in interface width driven by higher χ eff translates into lower LER. The effect of the IL on the layer thickness and interface width of a BCP are examined, along with the corresponding changes in LER in a DSA patterned sample. The results demonstrate that increased χ eff through additive blending will not necessarily translate to a lower LER, clarifying an important design criterion for future material systems.

Impact of L4/5 Posterior Interbody Fusion With or Without Decompression on Spinopelvic Alignment and Health-related Quality-of-Life Outcomes.

STUDY DESIGN: This was a retrospective case control study. OBJECTIVE: The objective was to determine the impact of single-level interbody fusion at L4/5 with or without concomitant decompression on various spinopelvic parameters and health-related quality-of-life (HRQOL) outcomes. SUMMARY OF BACKGROUND DATA: Recently, focus has swayed from a regional concern to a global sagittal alignment, more comprehensive approach in multilevel, corrective fusion for adult spinal deformity. However, only a few comprehensive studies have investigated the relationships between the various related spinopelvic parameters and HRQOL outcomes using single-level interbody fusion. MATERIALS AND METHODS: In total, 119 patients with lumbar degenerative disorders (mean age, 68 y; 38 males and 81 females) who underwent L4/5 single-level posterior interbody fusion with a minimum 2-year follow-up were included. Participants were divided into 2 groups according to preoperative sagittal modifiers of the SRS-Schwab adult spinal deformity classification. The correlation between spinopelvic parameters and HRQOL outcomes was investigated. Negative or positive values indicated lordosis. HRQOL outcomes were assessed using visual analog scale scores, Japanese Orthopedic Association Back Pain Evaluation Questionnaires (JOABPEQ), and short form-36 (SF-36). RESULTS: L4/5 local lordosis increased from 6.4±4.4 degrees preoperatively to 11.3±4.5 degrees at 2 years postoperatively (P<0.0001). Further analysis of the results also showed a correlation between change in L4/5 local lordosis and change in lumbar lordosis (LL) (rs=0.229, P=0.0143). The high pelvic incidence-LL (≥20 degrees, n=28) and high sagittal vertical axis groups (≥5 cm, n=29) had lower scores in walking ability, social life domains of JOABPEQ, and physical component summary scores of SF-36 preoperatively, and 2 years postoperatively. Fusion status did not affect the HRQOL outcomes, except that concomitant decompression at the adjacent disk level yielded lower SF-36 physical component summary scores 2 years postoperatively. CONCLUSIONS: Improvement in L4/5 local lordosis possibly triggers a simultaneous sequence of change in total LL after posterior single-level fusion. HRQOL outcomes were negatively affected by both preoperative and postoperative pelvic incidence-LL mismatch and global sagittal malalignment. LEVEL OF EVIDENCE: Level III.

Three-dimensional morphological analysis of cervical foraminal stenosis using dynamic flexion-extension computed tomography images.

BACKGROUND: Morphological features of foraminal stenosis in cervical spondylotic radiculopathy and the adequate extent of facet resection in posterior cervical foraminotomy remain uncertain. Herein, we evaluated quantitatively foraminal widths in cervical spondylotic radiculopathy on dynamic flexion-extension computed tomography using a novel three-dimensional analysis method and determined the extent of facet resection in posterior cervical foraminotomy. METHODS: Seventeen patients undergoing posterior cervical foraminotomy for cervical spondylotic radiculopathy were evaluated. A neuroforamen three-dimensional model was built from preoperative images of flexion-extension computed tomography myelography, and an ordinary cervical spine coordinate system and an original neuroforaminal coordinate system, were established. In the neuroforaminal coordinate system, minimum areas perpendicular to the long axis by the slices from inlet to outlet of neuroforamen and narrowest foraminal width in a slice of minimum area were measured. The location of the narrowest region from inlet of the foramen was calculated. Ratios of minimum and sufficient facet resection were obtained from the location of the narrowest region in the neuroforaminal coordinate system. RESULTS: The narrowest foraminal widths (flexion/extension) in the cervical spine coordinate system and the neuroforaminal coordinate system were 2.9/2.3 and 2.6/1.9 mm, respectively. The mean values of the location of the narrowest region (flexion/extension) were 0.27/0.22 and 0.50/0.45 mm, respectively, and the narrowest region in the neuroforaminal coordinate system was located on the outer side than in the cervical spine coordinate system (p < 0.001). The ratios of minimum and sufficient facet resection were 23 ± 8% and 32 ± 9%, respectively. CONCLUSIONS: The narrowest regions both in flexion and extension are located at the middle of the foramen based on the neuroforaminal coordinate system. Ordinary evaluation of axial computed tomography images likely underestimates the extent of facet resection, whereas certain extent of facet resection does not exceed 50% in cases with single-level cervical spondylotic radiculopathy. STUDY DESIGN: A retrospective case control study.

A novel concept of posterior decompression and instrumented fusion with selective lordotic correction for cervical ossification of the posterior longitudinal ligament.

PURPOSE: The recovery rate of Japanese Orthopedic Association (JOA) score with K-line (-) cervical ossification of the posterior longitudinal ligament (OPLL) for posterior decompression with in-situ fusion (PDF) tends to be lower than that of anterior decompression with fusion (ADF). However, ADF is a technically demanding operation and has ADF-specific complications. This prospective report introduced a novel concept of PDF with selective lordotic correction as well as prophylactic foraminal decompression. METHODS: Six consecutive patients (four men and two women; mean age, 61.8 years) were included. PDF was performed, attempting to create cervical lordosis to acquire a posterior shift of the spinal cord, while preventing postoperative C5 palsy by prophylactic facetectomy and selective lordotic correction. RESULTS: The mean recovery rate of JOA score at the final follow-up was 70.9 ±â€¯20.3%. The mean C2-C7 angle preoperatively and at final follow-up was 5.5 ±â€¯3.9° and 12.2 ±â€¯4.8°, respectively. No symptomatic nerve root palsy, except one case with transient C7 root iatrogenic palsy, was found. CONCLUSIONS: A novel concept of PDF with selective lordotic correction obtained recovery rates of JOA scores comparable to those of ADF. We believe that this method can improve PDF outcomes in patients with K-line (-) OPLL.

Quantitative radiographic analysis of foraminal re-stenosis after posterior cervical foraminotomy with laminoplasty.

Few studies have performed detailed radiographic evaluation of the cause of recurrent cervical radiculopathy. In this study, we aimed to perform quantitative analyses of foraminal re-stenosis after posterior cervical foraminotomy (PCF) concomitant with laminoplasty. Seventy-eight consecutive patients (50 males and 28 females, mean age of 62 years at surgery) with cervical spondylotic radiculomyelopathy who underwent PCF concomitant with open-door laminoplasty were included. A total of 133 foramina undergoing PCF were radiographically evaluated using the following parameters: disc height, focal range of motion at the corresponding disc level, foraminal diameter (FD) and facet joint width (FJW) in the axial view on computed tomography, and re-stenosis rate (RR) of foramina. RR was calculated as follows: (foraminal regrowth at 2 years after surgery)/(foraminal enlargement immediate postoperatively) × 100% (RR2y). FDs preoperatively, postoperatively, and at 2-year follow-up were 2.2, 6.6, and 4.6 mm, respectively, and FJWs were 14.5, 9.0, and 10.6 mm, respectively. Both parameters significantly increased at the 2-year follow-up (p < 0.001). The mean RR2y was 42% (range, -16 to 108%). On logistic regression analysis of risk factors for higher RR2y (>50%), only preoperative posterior disc height (PDH) (OR = 0.33; 95% CI = 0.193-0.563; p < 0.001) was identified. Receiver operating characteristic curve analysis showed that the cut-off value of RR2y 50% was 1-mm PDH (AUC 0.73, sensitivity 52%, specificity 86%, p value < 0.001). After posterior foraminotomy with laminoplasty, the enlarged foraminal space gradually decreased during the 2-year follow-up. Foraminal re-stenosis was mainly due to bone regrowth of the resected facet joint, which is caused by disc degeneration with loss of PDH.

Perioperative factors associated with favorable outcomes of posterior decompression and instrumented fusion for cervical ossification of the posterior longitudinal ligament: A retrospective multicenter study.

PURPOSE: Posterior decompression with instrumented fusion (PDF) is a suitable surgical treatment for K-line (-)-type cervical ossification of the posterior longitudinal ligament (OPLL). However, the adequate indications of PDF have not been clarified yet. The purpose of this study was to investigate the surgical results of PDF and perioperative factors that influence the surgical outcome, and to clarify the adequate indications of PDF. METHODS: Twenty-seven patients (21 men and 6 women, mean age: 61.4 years) who were diagnosed with a K-line (-)-type OPLL that was treated with PDF were included in this study. We evaluated these patients clinically and radiologically to investigate the outcomes of PDF and perioperative factors that influence improvements in the Japanese Orthopedic Association (JOA) score. RESULTS: The mean recovery rate of JOA score at the final follow-up examination was 53.3%. In the statistical analysis, the preoperative C2-C7 angle and the C2-C7 angle immediately postoperatively significantly predicted the surgical outcome. The C2-C7 angle immediately postoperatively was the only most important predictor. Using a receiver operating characteristic curve analysis, we found that the cutoff value of the C2-C7 angle immediately postoperatively for good outcomes (recovery rate of JOA score ≥50%) was -2.0°. CONCLUSIONS: PDF for K-line (-)-type OPLL patients with preoperative lordotic alignment can be expected to have favorable outcomes, which is the adequate indication for PDF. Since the C2-C7 angle immediately postoperatively was the most important predictor, the physician should pay attention to maintain the cervical lordotic alignment to enhance the surgical outcomes in surgical planning.

Ionic Liquids as Additives to Polystyrene- Block-Poly(Methyl Methacrylate) Enabling Directed Self-Assembly of Patterns with Sub-10 nm Features.

Polystyrene- block-poly(methyl methacrylate) (PS- b-PMMA) is one of the prototypical block copolymers in directed self-assembly (DSA) research and development, with standardized protocols in place for processing on industrially relevant 300 mm wafers. Scaling of DSA patterns to pitches below 20 nm using PS- b-PMMA, however, is hindered by the relatively low Flory-Huggins interaction parameter, χ. Here, we investigate the approach of adding small amounts of ionic liquids (ILs) into PS- b-PMMA, which selectively segregates into the PMMA domain and effectively increases the χ parameter and thus the pattern resolution. The amount of IL additive is small enough to result in limited changes in PS- b-PMMA's surface and interfacial properties, thus maintaining industry-friendly processing by thermal annealing with a free surface. Three different ILs are studied comparatively regarding their compositional process window, capability of increasing χ, and thermal stability. By adding ∼3.1 vol % of the champion IL into a low-molecular-weight PS- b-PMMA ( Mn = 10.3k- b-9.5k), we demonstrated DSA on chemically patterned substrates of lamellar structures with feature sizes <8.5 nm. Compatibility of the PS- b-PMMMA/IL blends with the standardized processes that have been previously developed suggests that such blend materials could provide a drop-in solution for sub-10 nm lithography with the processing advantages of PS- b-PMMA.

Surgical Outcomes of Posterior Spinal Fusion Alone Using Cervical Pedicle Screw Constructs for Cervical Disorders Associated With Athetoid Cerebral Palsy.

STUDY DESIGN: Retrospective case series. OBJECTIVE: The aim of this study was to investigate clinical outcomes after posterior spinal fusion (PSF) using cervical pedicle screw (CPS) constructs for cervical disorders associated with athetoid cerebral palsy (CP). SUMMARY OF BACKGROUND DATA: Traditionally, most patients with cervical myelopathy associated with CP have required combined anterior and posterior fusion to achieve solid stability against severe involuntary movement. METHODS: Thirty-one CP patients with cervical disorders who underwent PSF alone with a minimum 2-year follow-up (mean 58 months) were analyzed. All patients were treated with PSF using CPS constructs with or without decompression procedures. The average number of fused segments was 5.1 (range, 1-10 segments), and a halo jacket was applied in 16 patients for at least 2 months after surgery. Clinical outcomes using the Japanese Orthoedic Association scoring system (JOA score) and walking ability, radiographic sagittal alignment, fusion status, and surgery-related complications were evaluated. RESULTS: The JOA score improved from 8.3 points preoperatively to 10.9 points at the final follow-up (P < 0.05). Although no patients experienced deterioration in their walking ability postoperatively, 10 patients were unable to walk at the final follow-up. Sagittal alignment, including C0-2 angle, C2-7 angle, and local alignment in fused segments, was maintained postoperatively. Twenty-five patients achieved fusion at the final follow-up (fusion rate: 81%), and fivepatients with nonunion required additional surgery. With regard to complications, 5 patients encountered postoperative upper extremity palsy. CONCLUSION: The CPS construct is amenable to achieve a relatively high fusion rate without correction loss, and good clinical outcomes can be achieved with a posterior single approach for CP patients. In the future, efforts should be made to make appropriate decisions regarding the fusion area, take preventative measures against postoperative upper extremity palsy, and simplify external orthoses after surgery, especially with the use of a halo jacket. LEVEL OF EVIDENCE: 4.

Characteristics of spinopelvic alignment in Parkinson's disease: Comparison with adult spinal deformity.

PURPOSE: The characteristics and pathogenesis of spinopelvic alignment in Parkinsons's disease (PD) patients-including differences compared to non-PD subjects and their relationships with the severity of PD-have not been clarified. The aim of this study was to investigate the characteristics of spinopelvic alignment in patients with PD. METHODS: Forty-eight PD patients complaining of chronic low back pain were included (PD group). The PD condition, determined using the Hoehn and Yahr (H&Y) stage and Unified Parkinson Disease Rating Scale (UPDRS) score; radiographic spinopelvic alignment; lumbar range of motion (ROM); and low back pain-related quality of life assessments were evaluated. Fifty age- and sex-matched patients with adult spinal deformities were included as controls (ASD group). RESULTS: The spinopelvic alignments of the PD/ASD groups demonstrated sagittal vertical axes of 120.9/106.3 mm and pelvic incidences of 49.7/52.9°, with no significant differences. Conversely, there were significant differences in the thoracic kyphosis (TK; 27.6/16.7°), lumbar lordosis (-22.7/-7.9°), and pelvic tilt (25.3/34.4°) (all, p < 0.05). With regard to correlations with the PD condition, the H&Y stage demonstrated significant correlations with the sagittal vertical axis, thoracolumbar kyphosis, and lumbar ROM (all, p < 0.05), and the UPDRS score tended to correlate with the TK and thoracolumbar kyphosis (both, p < 0.01). CONCLUSION: Characteristic spinal conditions in PD exist, with progressed PD condition causing stooped posture with increased thoracic or thoracolumbar kyphosis and decreased lumbar ROM; moreover, global sagittal malalignment progresses without sufficient compensatory mechanisms such as loss of TK and pelvic retroversion.

Surgical treatment for osteoporotic thoracolumbar vertebral collapse using vertebroplasty with posterior spinal fusion: a prospective multicenter study.

PURPOSE: The study aimed to investigate the clinical outcomes and limitations after vertebroplasty with posterior spinal fusion (VP+PSF) without neural decompression for osteoporotic vertebral collapse. METHODS: We conducted a prospective multicenter study including 45 patients (12 men and 33 women, mean age: 77.0 years) evaluated between 2008 and 2012. Operation time, blood loss, visual analog scale (VAS) of back pain, neurological status, kyphosis angle in the fused area, and vertebral union of the collapsed vertebra were evaluated. RESULTS: The mean operation time was 162 min and blood loss was 381 mL. The postoperative VAS score significantly improved, and the neurological status improved in 35 patients (83 %), and none of the remaining patients demonstrated a deteriorating neurological status at two years post-operatively. The mean kyphosis angle pre-operatively, immediately post-operatively, and two years post-operatively was 23.8°, 10.7°, and 24.3°, respectively, and there was no significant difference between the angles pre-operatively and two years post-operatively. The extensive correction of kyphosis >16° was a risk factor for a higher correction loss and subsequent fracture. Union of the collapsed vertebra was observed in 43 patients (95 %) at two years post-operatively. CONCLUSIONS: The present study suggests that spinal stabilization rather than neural decompression is essential to treat OVC. Short-segment VP+PSF can achieve a high union rate of collapsed vertebra and provide a significant improvement in back pain or neurological status with less invasive surgery, but has a limit of kyphosis correction more than 16°.

Clinical features, outcomes, and survival factor in patients with vertebral osteomyelitis infected by methicillin-resistant staphylococci.

PURPOSE: To elucidate clinico-radiological features, therapeutic outcomes, and survival factors of vertebral osteomyelitis patients infected by methicillin-resistant staphylococci (MRS). METHODS: Vertebral osteomyelitis patients admitted to the orthopaedic department between 2007 and 2011 (n = 248) were selected for this multicenter study. We compared patients' backgrounds, therapeutic course, and in-hospital mortality between MRS and methicillin-susceptible staphylococci (MSS). We also examined survival factors of vertebral osteomyelitis due to MRS. RESULTS: Sixteen patients of MRS vertebral osteomyelitis and 55 patients of MSS were included in this study. In MRS vertebral osteomyelitis, the rates of comorbid diabetes mellitus, involvement of >2 vertebral bodies, in-hospital mortality, and operation of surgical debridement were higher compared to those in MSS vertebral osteomyelitis. Univariate analysis showed that operation of surgical debridement was a factor related to survival in MRS patients. CONCLUSIONS: Higher rate of comorbid diabetes mellitus, involvement of >2 vertebral bodies, in-hospital mortality, and performing surgical debridement are peculiar features of MRS vertebral osteomyelitis compared to MSS vertebral osteomyelitis. If patients with MRS vertebral osteomyelitis respond poorly to antibiotic therapy, it might be better to consider surgical debridement not to lose an opportunity of operation due to exacerbation of systemic conditions.

The characteristic clinical symptoms of C-4 radiculopathy caused by ossification of the posterior longitudinal ligament.

Cervical radiculopathy of the C2-4 spinal nerves is a rare condition and is poorly documented in terms of clinical symptoms, hindering its detection during initial patient screening based on imaging diagnostics. The authors describe in detail the clinical symptoms and successful surgical treatment of a patient diagnosed with isolated C-4 radiculopathy. This 41-year-old man suffered from sleep disturbance because of pain behind the right ear, along the right clavicle, and at the back of his neck on the right side. The Jackson and Spurling tests were positive, with pain radiating to the area behind the patient's ear. Unlike in cases of radiculopathy involving the C5-8 spinal nerves, no loss of upper-extremity motor function was seen. Magnetic resonance imaging showed foraminal stenosis at the C3-4 level on the right side, and multiplanar reconstruction CT revealed a beak-type ossification of the posterior longitudinal ligament in the foraminal region at the same level. In the absence of intracranial lesions or spinal cord compressive lesions, the positive Jackson and Spurling tests and the C3-4 foraminal stenosis were indicative of isolated C-4 radiculopathy. Microscopic foraminotomy was performed at the C3-4 vertebral level and the ossified lesion was resected. The patient's symptoms completely resolved immediately after surgery. To the authors' knowledge, this report is the first to describe the symptomatic features of isolated C-4 radiculopathy, in a case in which the diagnosis has been confirmed by both radiological findings and surgical outcome. Based on this case study, the authors conclude that the characteristic symptoms of C-4 radiculopathy are the presence of pain behind the ear and in the clavicular region in the absence of upper-limb involvement.

Two-year clinical and radiological outcomes of open-door cervical laminoplasty with prophylactic bilateral C4-C5 foraminotomy in a prospective study.

STUDY DESIGN: A prospective study. OBJECTIVE: To evaluate the 2-year outcomes of open-door cervical laminoplasty with prophylactic bilateral C4-C5 foraminotomy. SUMMARY OF BACKGROUND DATA: A prospective trial of prophylactic bilateral C4-C5 foraminotomy with open-door laminoplasty for cervical compression myelopathy showed a significant efficacy for preventing postoperative C5 palsy. However, in bilateral foraminotomy, there are concerns such as postoperative instability, hinge fracture, or nonunion, which may cause deterioration of neurological symptoms and neck pain. METHODS: A prospective trial was performed in 141 patients between 2009 and 2010 (group F). A group of 141 patients who underwent open-door laminoplasty without prophylactic foraminotomy from 2006 to 2008 served as a control group (group NF). Here, we report 2-year radiological and clinical data for 121 patients (follow-up rate: 85.8%) in group F and 115 patients (81.6%) in group NF. The 2 groups were demographically similar, except for the operation time. RESULTS: In group F, the mean rate of facet joint preservation was 71.4%. C2-C7 and C4-C5 lordosis and C4 translational movement were maintained postoperatively in both groups. The range of motion of C2-C7 and C4-C5 significantly decreased to about 80% of the preoperative values in both groups (P < 0.01). These radiological parameters and the incidence of hinge fracture and nonunion did not differ significantly between the groups. Visual analogue scale scores for neck pain were unchanged and significant recoveries (P < 0.001) in Japanese Orthopaedic Association scores were found in both groups. There were no significant differences in these clinical scores between the groups. The incidences of C5 palsy were 1.7% and 7.0% in groups F and NF, respectively (P = 0.043). CONCLUSION: Prophylactic bilateral C4-C5 foraminotomy did not adversely affect the 2-year radiological and clinical outcomes. Therefore, we conclude that this approach is an effective and desirable procedure for preventing postoperative C5 palsy. LEVEL OF EVIDENCE: 3.

Analysis of C5 palsy after cervical open-door laminoplasty: relationship between C5 palsy and foraminal stenosis.

STUDY DESIGN: A retrospective study. OBJECTIVE: To determine the clinical and imaging characteristics of postoperative C5 palsy after cervical open-door laminoplasty. SUMMARY OF BACKGROUND DATA: Postoperative C5 palsy is a common complication of cervical laminoplasty, and although there are several hypotheses regarding its etiology, the pathogenesis and preventive measures remain unidentified and many controversies remain. METHODS: A total of 141 consecutive patients (100 men and 41 women) who had undergone open-door laminoplasty for cervical myelopathy between 2006 and 2009 were included in this study. Postoperative C5 palsy was defined as deltoid muscle weakness of a grade <3 in manual muscle test. The patients were divided into 2 groups: 1 that had experienced C5 palsy (PG; the palsy group) and the other that had not (NPG; the nonpalsy group). The parameters evaluated were the incidence of C5 palsy, the level at which spinal cord compression appeared preoperatively, the spinal cord level showing a T2 high-signal intensity lesion on magnetic resonance imaging, T2 high-signal intensity lesions newly appearing postoperatively, and the diameters of the C4/5 and C5/6 foramens. RESULTS: The incidence of C5 palsy was 6.4% (9/141 cases). There were no significant differences between the 2 groups in sex, age, diagnosis, operation time, blood loss, level of spinal cord compression, level of T2 high-signal lesion, or new T2 high-signal lesions. The average diameter of the C4/5 foramen was 1.99 mm in the PG and 2.76 mm in the NPG (P<0.005). In contrast, the average diameter of the C5/6 foramen was 2.35 mm in PG and 2.50 mm in the NPG. CONCLUSIONS: There was a significant difference in the diameter of the C4/5 foramen between the PG and the NPG. The results suggest that the main etiology of C5 palsy is impairment of the C5 nerve root induced by preexisting C4/5 foraminal stenosis.

Polymethylmethacrylate augmentation of pedicle screws increases the initial fixation in osteoporotic spine patients.

STUDY DESIGN: A retrospective comparative study. OBJECTIVES: To investigate the clinical efficacy of polymethylmethacrylate (PMMA) augmentation in vertebral pseudarthrosis after osteoporotic vertebral fractures. SUMMARY OF BACKGROUND DATA: Despite being the most rigid form of posterior instrumentation, pedicle screws sometimes achieve poor initial fixation primarily in patients with osteoporosis. One method for improving pedicle screw fixation in osteoporotic spines is pedicle augmentation using bone cement such as PMMA. Although various biomechanical studies of osteoporotic spines have shown improved pullout strength of pedicle screws augmented with bone cement, there have been few studies that have examined the clinical significance of PMMA augmentation. METHODS: Thirty-eight patients with posterior fusion using pedicle screws for vertebral pseudarthrosis after osteoporotic vertebral fracture were included in the study. The level of fracture ranged from T7 to L5. The mean follow-up period was 31 months. Patients were divided into 2 groups: those with posterior instrumentation using pedicle screws augmented with PMMA (group C, N=17) and those without PMMA augmentation (group NC, N=21). Clinical and radiographic results for the 2 groups were compared. RESULTS: With the exception of osteoporotic status, there were no significant differences in the baseline data of the 2 groups. The incidence of clear zones around the pedicle screws was significantly suppressed in group C compared with group NC (29.4% vs. 71.4%). Correction loss was significantly decreased (3 degrees vs. 7.2 degrees) and fusion rate was significantly higher in group C (94.1% vs. 76.1%). Back pain improved in 64.7% of the group C patients. There were no perioperative complications related to the PMMA cement in group C. CONCLUSIONS: Reinforcement of pedicle screws using PMMA augmentation may be a feasible surgical technique for osteoporotic spines.

Can prophylactic bilateral C4/C5 foraminotomy prevent postoperative C5 palsy after open-door laminoplasty?: a prospective study.

STUDY DESIGN: A prospective study. OBJECTIVE: To evaluate the effectiveness of prophylactic C4/C5 microforaminotomy with open-door laminoplasty for cervical myelopathy in preventing postoperative C5 palsy. SUMMARY OF BACKGROUND DATA: Postoperative C5 palsy is a common complication of cervical laminoplasty. Although the etiology of C5 palsy and preventive measures remain unclear, we hypothesize that C5 palsy is caused by C5 nerve root impairment induced by potential C4/C5 foraminal stenosis and posterior shifting of the spinal cord after laminoplasty. METHODS: The study included 141 consecutive patients with cervical myelopathy (103 men and 38 women) who underwent open-door laminoplasty with prophylactic bilateral C4/C5 foraminotomy between 2009 and 2010. These were designated as the foraminotomy group (FG). One hundred forty-one consecutive patients (100 men and 41 women) who underwent open-door laminoplasty without prophylactic foraminotomy during 2006 to 2008 served as a control group. This was the nonforaminotomy group (NFG). The incidence of C5 palsy, operation time, blood loss, and the number of decompressed disc levels were recorded. RESULTS: The incidence of C5 palsy was 1.4% (2 of 141 cases) in the FG, and 6.4% (9 of 141 cases) in the NFG. The mean operation times were 129 and 102 minutes, respectively. There were significant differences in the incidence of C5 palsy and operation time (both comparisons, P < 0.05). There were no significant differences in blood loss or the number of decompressed disc levels (both comparisons, P > 0.05). CONCLUSION: Prophylactic bilateral C4/C5 microforaminotomy significantly decreased the incidence of postoperative C5 palsy. These results suggest that the main etiology of C5 palsy was C5 root impairment. However, 2 patients experienced C5 palsy despite undergoing prophylactic foraminotomy, which indicated that other factors including spinal cord impairment after acute decompression against cervical canal stenosis may also be considered as minor etiologies of C5 palsy. We conclude that prophylactic C4/C5 foraminotomy was an effective preventive measure against postoperative C5 palsy after laminoplasty.