Deep learning-based detection of lumbar spinal canal stenosis using convolutional neural networks.

BACKGROUND CONTEXT: Lumbar spinal canal stenosis (LSCS) is the most common spinal degenerative disorder in elderly people and usually first seen by primary care physicians or orthopedic surgeons who are not spine surgery specialists. Magnetic resonance imaging (MRI) is useful in the diagnosis of LSCS, but the equipment is often not available or difficult to read. LSCS patients with progressive neurologic deficits have difficulty with recovery if surgical treatment is delayed. So, early diagnosis and determination of appropriate surgical indications are crucial in the treatment of LSCS. Convolutional neural networks (CNNs), a type of deep learning, offers significant advantages for image recognition and classification, and work well with radiographs, which can be easily taken at any facility. PURPOSE: Our purpose was to develop an algorithm to diagnose the presence or absence of LSCS requiring surgery from plain radiographs using CNNs. STUDY DESIGN: Retrospective analysis of consecutive, nonrandomized series of patients at a single institution. PATIENT SAMPLE: Data of 150 patients who underwent surgery for LSCS, including degenerative spondylolisthesis, at a single institution from January 2022 to August 2022, were collected. Additionally, 25 patients who underwent surgery at 2 other hospitals were included for extra external validation. OUTCOME MEASURES: In annotation 1, the area under the curve (AUC) computed from the receiver operating characteristic (ROC) curve, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were calculated. In annotation 2, correlation coefficients were used. METHODS: Four intervertebral levels from L1/2 to L4/5 were extracted as region of interest from lateral plain lumbar spine radiographs totaling 600 images were obtained. Based on the date of surgery, 500 images derived from the first 125 cases were used for internal validation, and 100 images from the subsequent 25 cases used for external validation. Additionally, 100 images from other hospitals were used for extra external validation. In annotation 1, binary classification of operative and nonoperative levels was used, and in annotation 2, the spinal canal area measured on axial MRI was labeled as the output layer. For internal validation, the 500 images were divided into each 5 dataset on per-patient basis and 5-fold cross-validation was performed. Five trained models were registered in the external validation prediction performance. Grad-CAM was used to visualize area with the high features extracted by CNNs. RESULTS: In internal validation, the AUC and accuracy for annotation 1 ranged between 0.85-0.89 and 79-83%, respectively, and the correlation coefficients for annotation 2 ranged between 0.53 and 0.64 (all p<.01). In external validation, the AUC and accuracy for annotation 1 were 0.90 and 82%, respectively, and the correlation coefficient for annotation 2 was 0.69, using 5 trained CNN models. In the extra external validation, the AUC and accuracy for annotation 1 were 0.89 and 84%, respectively, and the correlation coefficient for annotation 2 was 0.56. Grad-CAM showed high feature density in the intervertebral joints and posterior intervertebral discs. CONCLUSIONS: This technology automatically detects LSCS from plain lumbar spine radiographs, making it possible for medical facilities without MRI or nonspecialists to diagnose LSCS, suggesting the possibility of eliminating delays in the diagnosis and treatment of LSCS that require early treatment.

Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion (PETLIF): Current Techniques, Clinical Outcomes, and Narrative Review.

Full endoscopic techniques are becoming more popular for degenerative lumbar pathologies. Percutaneous endoscopic lumbar interbody fusion (PETLIF) is a minimally invasive surgical technique for spondylolisthesis and lumbar spinal canal stenosis with instability. Nagahama first introduced PETLIF in 2019. This study investigated the clinical outcomes and complications of 24 patients who underwent PETLIF in our facility and compared them with previous studies. Literature searches were conducted on PubMed and Web of Science. The PETLIF surgical technique involves three steps to acquire disc height under general anesthesia. The procedure includes bone harvesting, spondylolisthesis reduction, endoscopic foraminoplasty, disc height expansion using an oval dilator, and intervertebral disc curettage. A cage filled with autologous bone is inserted into the disc space and secured with posterior fixation. Patients underwent PETLIF with an average operation time of 130.8 min and a blood loss of 24.0 mL. Postoperative hospital stays were 9.5 days. Improvement in VAS, disc height, spinal canal area, and % slip was observed, while lumbar lordosis remained unchanged. Complications included end plate injury, subsidence, and exiting nerve root injury. The differences between PETLIF and the extracted literature were found in patients' age, direct decompression, epidural or local anesthesia, approach, order of PPS, and cage insertion. In conclusion, PETLIF surgery is a practical, minimally invasive surgical technique for patients with lumbar degenerative diseases suffering from back and leg pain, demonstrating significant improvements in pain scores. However, it is essential to carefully consider the potential complications and continue to refine the surgical technique further to enhance the safety and efficacy of this procedure.

Evaluation of Surgical Indications for Full Endoscopic Discectomy at Lumbosacral Disc Levels Using Three-Dimensional Magnetic Resonance/Computed Tomography Fusion Images Created with Artificial Intelligence.

Background and Objectives: Although full endoscopic lumbar discectomy with the transforaminal approach (FED-TF) is a minimally invasive spinal surgery for lumbar disc herniation, the lumbosacral levels present anatomical challenges when performing FED-TF surgery due to the presence of the iliac bone. Materials and Methods: In this study, we simulated whether FED-TF surgery could be safely performed on a total of 52 consecutive cases with L5-S1 or L5-L6 disc herniation using fused three-dimensional (3D) images of the lumbar nerve root on magnetic resonance imaging (MRI) created with artificial intelligence and of the lumbosacral spine and iliac on computed tomography (CT) images. Results: Thirteen of the fifty-two cases were deemed operable according to simulated FED-TF surgery without foraminoplasty using the 3D MRI/CT fusion images. All 13 cases underwent FED-TF surgery without neurological complications, and their clinical symptoms significantly improved. Conclusions: Three-dimensional simulation may allow for the assessment from multiple angles of the endoscope entry and path, as well as the insertion angle. FED-TF surgery simulation using 3D MRI/CT fusion images could be useful in determining the indications for full endoscopic surgery for lumbosacral disc herniation.

Posterolateral full-endoscopic debridement and irrigation is effective in treating thoraco-lumbar pyogenic spondylodiscitis, except in cases with large abscess cavities.

PURPOSE: To determine the efficacy and poor prognostic factors of posterolateral full-endoscopic debridement and irrigation (PEDI) surgery for thoraco-lumbar pyogenic spondylodiscitis. METHODS: We included 64 patients (46 men, 18 women; average age: 63.7 years) with thoracic/lumbar pyogenic spondylodiscitis who had undergone PEDI treatment and were followed up for more than 2 years. Clinical outcomes after PEDI surgery were retrospectively investigated to analyze the incidence and risk factors for prolonged and recurrent infection. RESULTS: Of 64 patients, 53 (82.8%) were cured of infection after PEDI surgery, and nine (17.2%) had prolonged or recurrent infection. Multivariate analysis demonstrated that significant risk factors for poor prognosis included a large intervertebral abscess cavity (P = 0.02) and multilevel intervertebral infections (P < 0.05). CONCLUSION: PEDI treatment is an effective, minimally invasive procedure for pyogenic spondylodiscitis. However, a large intervertebral abscess space could cause instability at the infected spinal column, leading to prolonged or recurrent infection after PEDI. In cases with a large abscess cavity with or without vertebral bone destruction, endoscopic drainage alone may have a poor prognosis, and spinal fixation surgery could be considered.

Risk factors of multidrug-resistant pyogenic spondylitis in thoraco-lumbar spine: A retrospective study of 122 cases.

BACKGROUND: The number of spinal infections has been increasing in developed countries due to the increase of aged or immunosuppressed patients. Spondylitis caused by multidrug-resistant (MDR) bacterial infection often become intractable and require long-term antibiotic therapy and multiple surgeries. Therefore, it is of great importance to understand risk factors for MDR spinal infections. The aim of this study was to elucidate the risk factors for MDR bacterial spondylitis. METHODS: A total of 122 patients (82 men, 40 women; average age: 63.8 y) with thoracic/lumbar spondylitis who underwent posterolateral full-endoscopic debridement and irrigation were included. The organisms detected by this endoscopic procedure were investigated, and the incidence and risk factors for MDR bacterial infection were retrospectively analyzed. RESULTS: Cultures of specimens obtained by endoscopic procedures were positive in 78 patients (63.9%). Among 68 isolated bacteria, MDR bacteria accounted for 47.1%. Multivariate analysis showed that significant risk factors for MDR bacterial infection included autoimmune connective tissue disease (P = 0.03) and central venous catheter (P = 0.02). The incidence of MDR bacteria in patients who were administered a broad-spectrum antibiotic for more than 1 month preoperatively was 64.0%, which was significantly higher than in patients who were administered a broad-spectrum antibiotic for less than 1 month and patients who were administered a narrow-spectrum antibiotic (P < 0.01, P < 0.01, respectively). CONCLUSIONS: The significant risk factors for MDR bacterial spondylitis included immunosuppressed conditions, such as autoimmune connective tissue disease, presence of central venous catheter, and longer administration periods of a broad-spectrum antibiotic. In patients with pyogenic spondylitis who could not be controlled with previous antibiotics and whose result of culture was negative, administration of anti-MRSA antibiotics would be considered when they have the risk factors identified in this study.

Unintentional Fusion in Preserved Facet Joints without Bone Grafting after Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion.

INTRODUCTION: A percutaneous endoscopic transforaminal lumbar interbody fusion (PETLIF) procedure has been previously developed. During postoperative follow-up, in some patients, bone fusion occurred between opened facet joints, despite not having bone grafting in the facet joints. Here, we investigated facet fusion's frequency and tendencies following PETLIF. METHODS: A retrospective analysis was conducted on a prospectively collected, nonrandomized series of patients. Forty-two patients (6 males and 36 females, average age: 69.9 years) who underwent single-level PETLIF at our hospital from February 2016 to March 2019 were included in this study. Patients were assessed with lumbar X-ray images and computed tomography (CT) prior to, immediately after, and 1 year after surgery. RESULTS: Pseudarthrosis was not observed in any patients, and facet fusion was observed in 26 of 42 post-PETLIF patients (61.9%) by CT 1 year postoperatively. The average interfacet distance increased from 1.3 mm preoperatively to 4.5 mm postoperatively, and facet fusion was observed under the opened conditions of 3.8 mm at 1 year. Segmental lordotic angle of the fusion segment in the lumbar X-ray images was significantly larger in the facet fusion subgroup prior to surgery, immediately following surgery, and 1 year after surgery compared to the facet non-fusion group (p=0.02, p<0.01, p=0.01, respectively). There were no significant differences in patient background, correction loss of segmental lordosis, interfacet distance, or clinical score between the facet fusion and facet non-fusion subgroups. CONCLUSIONS: Facet fusion was achieved over time within the facet joints that were opened through indirect decompression after PETLIF. We hypothesized that the preserved facet joints potentially became the base bed for spontaneous bone fusion due to the preserved facet joint capsule and surrounding soft tissue, which maintained cranio-caudal facet traffic and blood circulation in the facet joints. The complete preservation of the facet joints was a key advantage of minimally invasive lumbar interbody fusion procedures. LEVEL OF EVIDENCE: Level III.

Morphological analysis of Kambin's triangle using 3D CT/MRI fusion imaging of lumbar nerve root created automatically with artificial intelligence.

PURPOSE: We developed a software program that automatically extracts a three-dimensional (3D) lumbar nerve root image from magnetic resonance imaging (MRI) lumbar nerve volume data using artificial intelligence. The aim of this study is to evaluate the morphology of Kambin's triangle in three dimensions based on an actual endoscopic transforaminal surgical approach using three-dimensional (3D) computed tomography (CT)/ magnetic resonance imaging (MRI) fusion images of the lumbar spine and nerve tissue. METHODS: Three-dimensional lumbar spine/nerve images of 100 patients (31 males and 69 females; mean age, 66.8 years) were used to evaluate the relationship between the superior articular process (SAP), exiting nerve root (ENR), and dural canal at the L2/3, L3/4, and L4/5 levels at 45° and 60° approach angles. RESULTS: The SAP-ENR distance at 60° was the greatest at L4/5 and was significantly greater at L2/3 and L4/5 than at L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distance at 45° was the greatest at L2/3, and it was larger in L2/3 and L4/5 than in L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distances at L4/5 were significantly greater at 60° than at 45° (P < 0.01). The dural canal was located within Kambin's triangle on the plane of the upper endplate of the lower vertebra at L2/3 in 41.5% of the cases and at L3/4 in 14% of the cases at 60° but not at L4/5. CONCLUSION: The 3D lumbar spine/nerve image enabled a combined assessment of the positional relationship between the SAP, ENR, and dural canal to quantify the safety zone of practical endoscopic spinal surgery using a transforaminal approach. Three-dimensional lumbar spine/nerve images could be useful for examining parameters, including bones and nerves, to ensure the safety of surgery.

Early Clinical Results of Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion: A New Modified Technique for Treating Degenerative Lumbar Spondylolisthesis.

INTRODUCTION: Lumbar interbody fusion is used to treat degenerative lumbar spondylolisthesis with instability. We developed a device that safely expands a percutaneous path through Kambin's triangle and used it via a new technique: percutaneous endoscopic transforaminal lumbar interbody fusion (PETLIF). We report in this study the details and outcomes of this procedure after a one year follow-up. METHODS: Twenty-five patients requiring interbody fusion for degenerative spondylolisthesis of the L4 vertebra were enrolled in this study. The procedure involved percutaneous posterior pedicle screw placement to correct spondylolisthesis. After the exterior of the L5 vertebra superior articular protrusion was shaved with a percutaneous endoscopic drill in order to expand the safe zone, the oval sleeve was inserted through Kambin's triangle and was rotated to expand the disk height and create a path toward the vertebral disk. The interbody cage was inserted against the J-shaped nerve retractor, with the exiting nerve root retracted. Indirect decompression of spinal canal stenosis was expected because the vertebral body spondylolisthesis had been corrected and the interbody distance was expanded. Thus, no direct decompression was performed posterolaterally. RESULTS: The mean follow-up period, surgery time, and blood loss were 22.7 months, 125.4 min, and 64.8 mL, respectively. The Japanese Orthopaedic Association score improved from 13.3 to 28.0. The Roland-Morris Disability Questionnaire score improved from 10.3 to 3.3. All items were evaluated both preoperatively and one year postoperatively. Bone fusion was observed one year postoperatively in 22 out of 25 patients. CONCLUSIONS: These results demonstrate the feasibility and efficacy of PETLIF for treating degenerative lumbar spondylolisthesis. This minimally invasive procedure is useful and has wide applicability. To obtain safe and favorable results, necessary surgical techniques must be mastered, and surgical equipment, including that for neural monitoring, is required.

Cervical myelopathy due to atraumatic odontoid fracture in patients with rheumatoid arthritis: A case series.

To highlight the risk of cervical myelopathy due to occult, atraumatic odontoid fracture in patients with rheumatoid arthritis, we retrospectively reviewed radiographic findings and clinical observations for 7 patients with this disorder. This fracture tends to occur in patients with long-lasting rheumatoid arthritis and to be misdiagnosed as simple atlantoaxial dislocation. Since this fracture causes multidirectional instability between C1 and C2 and is expected to have poor healing potential due to bone erosion and inadequate blood supply, posterior spinal arthrodesis surgery is indicated upon identification of the fracture to prevent myelopathy.

18F-FDG-PET/CT better localizes active spinal infection than MRI for successful minimally invasive surgery.

BACKGROUND: Surgical debridement is often required to treat spinal infections. Successful surgery requires accurate localization of the active infections, however, current imaging technique still requires surgeons' experience to narrow the surgical fields to achieve less invasive procedures. PURPOSE: To investigate the use of F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for successful surgical planning. MATERIAL AND METHODS: Nine patients with suspected spinal infection underwent magnetic resonance imaging (MRI) and FDG-PET/CT before surgery to locate active foci of infections. The spinal structures were divided into seven compartments at each intervertebral disc level for a total of 315 compartments investigated. The same classification system was used to design operating fields for histological correlation. RESULTS: FDG-PET/CT diagnosed fewer compartments as active infection (34 compartments, 10.8%) than MRI (62 compartments, 19.7%, P = 0.002). Surgical exploration was performed in 49 compartments, and demonstrated active infection in 25 compartments. The sensitivity / specificity of FDG-PET/CT was 100% / 79%, respectively, which was superior to those of MRI, 76% / 42%. Foci of active infection showed hypermetabolic activity with a SUVmax of 7.1 ± 2.6 (range, 3.0-12.7). Receiver operating characteristic (ROC) analysis indicated an optimal threshold for active spinal infection at a SUVmax of 4.2, corresponding to a sensitivity of 90.3% and specificity of 91.2%. CONCLUSION: FDG-PET/CT demonstrated limited areas of abnormality allowing accurate delineation, and is thus useful to narrow the surgical fields. Since overall diagnostic accuracy of FDG-PET/CT was superior to that of MRI, FDG-PET/CT is a useful technique to narrow the surgical field for successful less invasive surgery.

Surgical treatment of Lenke 1 thoracic adolescent idiopathic scoliosis with maintenance of kyphosis using the simultaneous double-rod rotation technique.

STUDY DESIGN: Retrospective analysis of a prospectively collected, consecutive, nonrandomized series of patients. OBJECTIVE: To assess the surgical outcomes of the simultaneous double-rod rotation technique for treating Lenke 1 thoracic adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: With the increasing popularity of segmental pedicle screw spinal reconstruction for treating AIS, concerns regarding the limited ability to correct hypokyphosis have also increased. METHODS: A consecutive series of 32 patients with Lenke 1 main thoracic AIS treated with the simultaneous double-rod rotation technique at our institution was included. Outcome measures included patient demographics, radiographical measurements, and Scoliosis Research Society questionnaire scores. RESULTS: All 32 patients were followed up for a minimum of 2 years (average, 3.6 yr). The average main thoracic Cobb angle correction rate and the correction loss at the final follow-up were 67.8% and 3.3°, respectively. The average preoperative thoracic kyphosis (T5-T12) was 11.9°, which improved significantly to 20.5° (P < 0.0001) at the final follow-up. An increase in thoracic kyphosis was significantly correlated with an increase in lumbar lordosis at the final follow-up (r = 0.42). The average preoperative vertebral rotation angle was 19.7°, which improved significantly after surgery to 14.9° (P = 0.0001). There was no correlation between change in thoracic kyphosis and change in apical vertebral rotation (r =-0.123). The average preoperative total Scoliosis Research Society questionnaire score was 3.0, which significantly improved to 4.4 (P < 0.0001) at the final follow-up. Throughout surgery and even after, there were no instrumentation failures, pseudarthrosis, infection of the surgical site, or clinically relevant neurovascular complications. CONCLUSION: The simultaneous double-rod rotation technique for treating Lenke 1 AIS provides significant sagittal correction of the main thoracic curve while maintaining sagittal profiles and correcting coronal and axial deformities. LEVEL OF EVIDENCE: 4.

Anterior decompression and strut graft versus posterior decompression and pedicle screw fixation with vertebroplasty for osteoporotic thoracolumbar vertebral collapse with neurologic deficits.

BACKGROUND CONTEXT: With the increase of the elderly population, osteoporotic vertebral fractures have been frequently reported. Surgical intervention is usually recommended in osteoporotic vertebral collapse with neurologic deficits. However, very few reports on surgical interventions exist. PURPOSE: To compare surgical results of anterior and posterior procedures for treating osteoporotic thoracolumbar vertebral collapse with sustained neurologic deficits. STUDY DESIGN: Retrospective comparative study. PATIENT SAMPLE: Fifty patients who sustained osteoporotic thoracolumbar vertebral collapse with neurologic deficits were treated either by anterior decompression and strut graft (n=32) or by posterior decompression and pedicle screw fixation with vertebroplasty (n=18). OUTCOME MEASURES: Incidence of complications, sagittal Cobb angle, spinal canal encroachment, and Japanese Orthopedic Association score. METHODS: The authors retrospectively reviewed the results of a consecutive series of patients undergoing anterior decompression and strut graft or posterior decompression and pedicle screw fixation with vertebroplasty for osteoporotic thoracolumbar vertebral collapse with neurologic deficits. Operative notes, clinical charts, and radiographs were analyzed. RESULTS: Operative time was similar between the groups, but intraoperative blood loss was significantly lower in the posterior group. All patients showed neurologic recovery. No significant difference was observed in the neurologic improvement, kyphosis correction angle, and loss of correction. Perioperative respiratory complications were found in 11 patients (34%) in the anterior group. In the anterior group, early posterior reinforcement was required in patients with very low bone density below 0.60 g/cm(2) and/or in those with three segments of instrumentation for two vertebral collapses. Posterior group patients did not undergo additional surgery. CONCLUSIONS: Anterior reconstruction for osteoporotic vertebral collapse is significant because anterior elements, particularly those at the thoracolumbar junction, play a major role in load bearing. However, difficulties arise when anterior reconstruction is performed in cases with very low bone density and in those with multiple vertebral collapse.

A retrospective study of congenital osseous anomalies at the craniocervical junction treated by occipitocervical plate-rod systems.

PURPOSE: To evaluate the effectiveness of posterior occipitocervical reconstruction using the anchors of cervical pedicle screws and plate-rod systems for patients with congenital osseous anomalies at the craniocervical junction. METHODS: Twenty patients with congenital osseous lesions who underwent posterior occipitocervical fusion using the anchors of cervical pedicle screws and plate-rod systems for reduction and fixation from 1996 to 2009 were reviewed. The lesions included os odontoideum, occipitalization of the atlas, congenital C2-3 fusion, congenital atlantoaxial subluxation, congenital basilar invagination and combined anomalies. The clinical assessment and the measurements of the images were performed preoperatively, postoperatively and at most recent follow-up. RESULTS: The combined deformity of flexion of the occipitoatlantoaxial complex and invagination of the odontoid process associated with congenital osseous lesions at the craniocervical junction was corrected by application of combined forces of extension and distraction between the occiput and the cervical pedicle screws. Preoperative myelopathy improved in 94.7% patients. The mean Ranawat value, Redlund-Johnnell value, atlantodental distance, occiput (O)-C2 angle, and C2-C7 lordosis angle improved postoperatively and was sustained at most recent follow-up. The mean cervicomedullary angle improved from 129.3° preoperatively to 153.3° postoperatively. The mean range of motion at the lower adjacent motion segment remained unchanged at most recent follow-up. The fusion rate was 95%. CONCLUSIONS: The results of the present study indicate that posterior occipitocervical reconstruction using the anchors of cervical pedicle screws and plate-rod systems is an effective technique for treatment of deformities and/or instability caused by congenital osseous anomalies at the craniocervical junction.

Impact of deep extensor muscle-preserving approach on clinical outcome of laminoplasty for cervical spondylotic myelopathy: comparative cohort study.

INTRODUCTION: This study aimed to compare patients undergoing deep extensor muscle-preserving laminoplasty and conventional open-door laminoplasty for the treatment of cervical spondylotic myelopathy (CSM). We specifically assessed axial pain, cervical spine function, and quality of life (QOL) with a minimum follow-up period of 3 years. PATIENTS AND METHODS: Ninety patients were divided into two groups and underwent either conventional open-door laminoplasty (CL group) or laminoplasty using the deep extensor muscle-preserving approach (MP group). The latter approach was undertaken by preserving the multifidus and semispinalis cervicis attachments followed by open-door laminoplasty and resuturing of the bisected spinous processes at each decompression level. The mean follow-up period was 7.7 years (range, 36-128 months). Preoperative and follow-up evaluations included the Japanese Orthopaedic Association (JOA) score, a tentative version of the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) including cervical spine function and QOL, and a visual analog scale (VAS) for axial pain. Radiological analyses included cervical lordosis and flexion-extension range of motion (C2-7), as well as deep extensor muscle areas on axial magnetic resonance imaging (MRI). RESULTS: The mean number of decompressed laminae was 3.9 and 3.3 in CL and MP groups, respectively, which was statistically equivalent. Japanese Orthopaedic Association recovery was statistically equivalent between the two groups. The MP group demonstrated a superior QOL score (57 vs. 46%) compared with the CL group at final follow-up (p < 0.05). Mean VAS scores at final follow-up were 2.2 and 4.3 in MP and CL groups, respectively (p < 0.05). Cervical lordosis and flexion-extension range of motion were statistically equivalent. The percentage deep muscle area on MRI was significantly lesser in the CL group compared with the MP group (58 vs. 102%; p < 0.01). CONCLUSION: We demonstrated the superiority of deep extensor muscle-preserving laminoplasty in terms of postoperative axial pain, QOL, and prevention of atrophy of the deep extensor muscles over conventional open-door laminoplasty for the treatment of CSM.

Laminoplasty for cervical myelopathy.

This article reviews cervical laminoplasty. The origin of cervical laminoplasty dates back to cervical laminectomy performed in Japan ~50 years ago. To overcome poor surgical outcomes of cervical laminectomy, many Japanese orthopedic spine surgeons devoted their lives to developing better posterior decompression procedures for the cervical spine. Thanks to the development of a high-speed surgical burr, posterior decompression procedures for the cervical spine showed vast improvement from the 1970s to the 1980s, and the original form of cervical laminoplasty was determined. Since around 2000, surgeons performing cervical laminoplasty have been adopting less invasive procedures for the posterior cervical muscle structures so as to minimize postoperative axial neck pain and obtain better functional outcomes of the cervical spine. This article covers the history of cervical laminoplasty, surgical procedures, the benefits and limitation of this procedure, and surgery-related complications.

Does alendronate disturb the healing process of posterior lumbar interbody fusion? A prospective randomized trial.

OBJECT: Bisphosphonate medications are widely used for the treatment of osteoporosis, but they might disturb the healing process of spinal fusion. The object of this prospective randomized controlled study was to evaluate the effect of bisphosphonate medication on spinal fusion through radiographic, clinical, and biological assessments. METHODS: A total of 40 patients with osteoporosis who were candidates for single-level posterior lumbar interbody fusion were randomly assigned to the alendronate group (alendronate sodium 35 mg/week) or the control group (vitamin D, alfacalcidol 1 µg/day). Pedicle screw fixation and carbon polyetheretherketone cages were used for all the patients. Bone graft material was prepared as a mixture of local bone and ß-tricalcium phosphate in a ratio of 2:1. Functional radiography and CT scans were used to evaluate fusion status and cage subsidence. The incidence of vertebral compression fractures (VCFs) occurring after surgery (subsequent VCFs) was assessed by means of MR imaging. Bridging bone formation was graded into 3 categories: Grade A (bridging bone through bilateral cages), Grade B (bridging bone through a unilateral cage), or Grade C (incomplete bony bridging). A solid fusion was defined as less than 5° of angular motion in flexion-extension radiographs and the presence of bridging bone through the cage (Grade A or B). Clinical outcome was evaluated by means of the Oswestry Disability Index. Bone metabolic markers (serum bone alkaline phosphatase, serum and urine Type I collagen cross-linked N-telopeptides) were measured to investigate the biological effects of alendronate on spinal fusion. RESULTS: Bridging bone formation (Grade A or B) was more frequently observed in the alendronate group at all postoperative assessment periods. At 1-year postoperative follow-up, a solid fusion was achieved in 95% of the patients in the alendronate group and 65% of those in the control group. Cage subsidence (> 2 mm) was observed in 5% of the alendronate group and 29% of the control group. No vertebral fractures were observed in the alendronate group, whereas 24% of patients in the control group showed subsequent VCFs. There was no statistically significant between-groups difference in clinical outcomes, but poor clinical results in the control group were associated with pseudarthrosis and subsequent VCFs. Biochemical analysis of bone turnover demonstrated that alendronate inhibited bone resorption from the early phase of the fusion process and also suppressed bone formation after 6 months postoperatively. CONCLUSIONS: Favorable mechanical circumstances provided by alendronate overcame its detrimental biological effect on the healing process of spinal fusion. The authors recommend that osteoporosis patients undergoing spinal fusion take bisphosphonates throughout the postoperative period.