Does spinopelvic alignment affect femoral head cartilage and the proximal femoral physis in slipped capital femoral epiphysis? A finite element analysis.

BACKGROUND: Slipped capital femoral epiphysis is a prevalent pediatric hip disorder. Recent studies suggest the spine's sagittal profile may influence the proximal femoral growth plate's slippage, an aspect not extensively explored. This study utilizes finite element analysis to investigate how various spinopelvic alignments affect shear stress and growth plate slip. METHODS: A finite element model was developed from CT scans of a healthy adult male lumbar spine, pelvis, and femurs. The model was subjected to various sagittal alignments through reorientation. Simulations of two-leg stance, one-leg stance, walking heel strike, ascending stairs heel strike, and descending stairs heel strike were conducted. Parameters measured included hip joint contact area, stress, and maximum growth plate Tresca (shear) stress. FINDINGS: Posterior pelvic tilt cases indicated larger shear stresses compared to the anterior pelvic tilt variants except in two leg stance. Two leg stance resulted in decreases in the posterior tilted pelvi variants hip contact and growth plate Tresca stress compared to anterior tilted pelvi, however a combination of posterior pelvic tilt and high pelvic incidence indicated larger shear stresses on the growth plate. One leg stance and heal strike resulted in higher shear stress on the growth plate in posterior pelvic tilt variants compared to anterior pelvic tilt, with a combination of posterior pelvic tilt and high pelvic incidence resulting in the largest shear. INTERPRETATION: Our findings suggest that posterior pelvic tilt and high pelvic incidence may lead to increased shear stress at the growth plate. Activities performed in patients with these alignments may predispose to biomechanical loading that shears the growth plate, potentially leading to slip.

Current Concepts of Cervical Spine Alignment, Sagittal Deformity, and Cervical Spine Surgery.

There are not many reports on cervical spine alignment, and only a few analyze ideal surgical approaches and optimal amounts of correction needed for the various types of deformity. We comprehensively reviewed the present literature on cervical spinal deformities (with or without myelopathy) and their surgical management to provide a framework for surgical planning. A general assessment of the parameters actually in use and correlations between cervical and thoracolumbar spine alignment are provided. We also analyzed posterior, anterior, and combined cervical surgical approaches and indications for the associated techniques of laminoplasty, laminectomy and fusion, and anterior cervical discectomy and fusion. Finally, on the basis of the NDI, SF-36, VAS, and mJOA questionnaires, we fully evaluated the outcomes and measures of postoperative health-related quality of life. We found the need for additional prospective studies to further enhance our understanding of the importance of cervical alignment when assessing and treating cervical deformities with or without myelopathy. Future studies need to focus on correlations between cervical alignment parameters, disability scores, and myelopathy outcomes. Through this comprehensive literature review, we offer guidance on practical and important points of surgical technique, cervical alignment, and goals surgeons can meet to improve symptoms in all patients.

Finite element study on post-screw removal stress in toy poodle radius with different plate designs and screw arrangements.

Background: The study employs finite element analysis to investigate stress distribution in the radius of toy poodles after screw removal. The examination focuses on the biomechanical implications of varied screw hole configurations using 1.5 and 2.0-mm locking compression plates (LCPs) with notched head T-Plates. Aim: To provide a noninvasive approach to analyzing the immediate consequences of screw removal from the radius bone in toy poodles. Specifically, it explores the impact of varied plate designs and screw arrangements on stress distribution within the forelimb bones. Methods: The study constructs a three-dimensional bone model of the toy poodle's forelimb based on computed tomography (CT) images. Simulations were designed to replicate jumping and landing from a 40 cm height, comparing stress distribution in the radius post-screw removal. Results: The analysis reveals significant variations in stress distribution patterns between the two LCPs. The radius implanted with the 2.0-mm LCP displays a uniform stress distribution, contrasting with the 1.5-mm plates. Localized stress concentration is observed around the screw holes, while trabecular bone regions near the screw holes exhibit lower stress levels. Conclusion: The study highlights the plate designs and screw configurations that affect bone stress in toy poodle forelimbs post-screw removal. The findings provide valuable insights for veterinarians, aiding informed decisions in veterinary orthopedic practices.

Pelvic Ring Fractures: A Biomechanical Comparison of Sacral and Lumbopelvic Fixation Techniques.

BACKGROUND CONTEXT: Pelvic ring fractures are becoming more common in the aging population and can prove to be fatal, having mortality rates between 10% and 16%. Stabilization of these fractures is challenging and often require immediate internal fixation. Therefore, it is necessary to have a biomechanical understanding of the different fixation techniques for pelvic ring fractures. METHODS: A previously validated three-dimensional finite element model of the lumbar spine, pelvis, and femur was used for this study. A unilateral pelvic ring fracture was simulated by resecting the left side of the sacrum and pelvis. Five different fixation techniques were used to stabilize the fracture. A compressive follower load and pure moment was applied to compare different biomechanical parameters including range of motion (contralateral sacroiliac joint, L1-S1 segment, L5-S1 segment), and stresses (L5-S1 nucleus stresses, instrument stresses) between different fixation techniques. RESULTS: Trans-iliac-trans-sacral screw fixation at S1 and S2 showed the highest stabilization for horizontal and vertical displacement at the sacral fracture site and reduction of contralateral sacroiliac joint for bending and flexion range of motion by 165% and 121%, respectively. DTSF (Double transiliac rod and screw fixation) model showed highest stabilization in horizontal displacement at the pubic rami fracture site, while the L5_PF_W_CC (L5-Ilium posterior screw fixation with cross connectors) and L5_PF_WO_CC (L5-Ilium posterior screw fixation without cross connectors) showed higher rod stresses, reduced L1-S1 (approximately 28%), and L5-S1 (approximately 90%) range of motion. CONCLUSIONS: Longer sacral screw fixations were superior in stabilizing sacral and contralateral sacroiliac joint range of motion. Lumbopelvic fixations displayed a higher degree of stabilization in the horizontal displacement compared to vertical displacement of pubic rami fracture, while also indicating the highest rod stresses. When determining the surgical approach for pelvic ring fractures, patient-specific factors should be accounted for to weigh the advantages and disadvantages for each technique.

Elucidation of the radius and ulna fracture mechanisms in toy poodle dogs using finite element analysis.

Fractures occurring in the distal radius and ulna of toy breed dogs pose distinctive challenges for veterinary practitioners, requiring specialized treatment approaches primarily based on anatomical features. Finite Element Analysis (FEA) was applied to conduct numerical experiments to determine stress distribution across the bone. This methodology offers an alternative substitute for directly investigating these phenomena in living dog experiments, which could present ethical obstacles. A three-dimensional bone model of the metacarpal, carpal, radius, ulna, and humerus was reconstructed from Computed Tomography (CT) images of the toy poodle and dachshund forelimb. The model was designed to simulate the jumping and landing conditions from a vertical distance of 40 cm to the ground within a limited timeframe. The investigation revealed considerable variations in stress distribution patterns between the radius and ulna of toy poodles and dachshunds, indicating notably elevated stress levels in toy poodles compared to dachshunds. In static and dynamic stress analysis, toy poodles exhibit peak stress levels at the distal radius and ulna. The Von Mises stresses for toy poodles reach 90.07 MPa (static) and 1,090.75 MPa (dynamic) at the radius and 1,677.97 MPa (static) and 1,047.98 MPa (dynamic) at the ulna. Conversely, dachshunds demonstrate lower stress levels for 5.39 MPa (static) and 231.79 MPa (dynamic) at the radius and 390.56 MPa (static) and 513.28 MPa (dynamic) at the ulna. The findings offer valuable insights for modified treatment approaches in managing fractures in toy breed dogs, optimizing care and outcomes.

Fracture risk assessment of vascularized medial femoral condylar bone graft: A finite element analysis.

BACKGROUND: Vascularized medial femoral condyle (MFC) bone graft is useful for pseudarthrosis and osteonecrosis, but has the risk of fracture as a complication. This study aimed to create multiple three-dimensional (3D) finite element (FE) femur models to biomechanically evaluate the fracture risk in the donor site of a vascularized MFC bone graft. METHODS: Computer tomography scans of the femurs of nine patients (four males and five females) with no left femur disease were enrolled in the study. A 3D FE model of the left femur was generated based on the CT images taken from the patients. The descending genicular artery (DGA), the main nutrient vessel in vascularized MFC bone grafts, divides into the proximal transversal branch (TB) and the distal longitudinal branch (LB) before entering the periosteum. Thirty-six different bone defect models with different sizes and locations of the harvested bone were created. RESULTS: The highest stress was observed in the proximal medial and metaphyseal portions under axial and external rotation, respectively. In the bone defect model, the stress was most elevated in the extracted region's anterior or posterior superior part. Stress increased depending on proximal location and harvested bone size. CONCLUSION: Increasing the size of the bone graft proximally raises the stress at the site of bone extraction. For bone grafting to non-load-bearing areas, bone grafting distally using LB can reduce fracture risk. If TB necessitates a larger proximal bone extraction, it is advisable to avoid postoperative rotational loads.

Compensation Method for Missing and Misidentified Skeletons in Nursing Care Action Assessment by Improving Spatial Temporal Graph Convolutional Networks.

With the increasing aging population, nursing care providers have been facing a substantial risk of work-related musculoskeletal disorders (WMSDs). Visual-based pose estimation methods, like OpenPose, are commonly used for ergonomic posture risk assessment. However, these methods face difficulty when identifying overlapping and interactive nursing tasks, resulting in missing and misidentified skeletons. To address this, we propose a skeleton compensation method using improved spatial temporal graph convolutional networks (ST-GCN), which integrates kinematic chain and action features to assess skeleton integrity and compensate for it. The results verified the effectiveness of our approach in optimizing skeletal loss and misidentification in nursing care tasks, leading to improved accuracy in calculating both skeleton joint angles and REBA scores. Moreover, comparative analysis against other skeleton compensation methods demonstrated the superior performance of our approach, achieving an 87.34% REBA accuracy score. Collectively, our method might hold promising potential for optimizing the skeleton loss and misidentification in nursing care tasks.

Resting-state functional magnetic resonance imaging indices are related to electrophysiological dysfunction in degenerative cervical myelopathy.

The age-related degenerative pathologies of the cervical spinal column that comprise degenerative cervical myelopathy (DCM) cause myelopathy due spinal cord compression. Functional neurological assessment of DCM can potentially reveal the severity and pathological mechanism of DCM. However, functional assessment by conventional MRI remains difficult. This study used resting-state functional MRI (rs-fMRI) to investigate the relationship between functional connectivity (FC) strength and neurophysiological indices and examined the feasibility of functional assessment by FC for DCM. Preoperatively, 34 patients with DCM underwent rs-fMRI scans. Preoperative central motor conduction time (CMCT) reflecting motor functional disability and intraoperative somatosensory evoked potentials (SEP) reflecting sensory functional disability were recorded as electrophysiological indices of severity of the cervical spinal cord impairment. We performed seed-to-voxel FC analysis and correlation analyses between FC strength and the two electrophysiological indices. We found that FC strength between the primary motor cortex and the precuneus correlated significantly positively with CMCT, and that between the lateral part of the sensorimotor cortex and the lateral occipital cortex also showed a significantly positive correlation with SEP amplitudes. These results suggest that we can evaluate neurological and electrophysiological severity in patients with DCM by analyzing FC strengths between certain brain regions.

Transcranial Magnetic Stimulation in the Diagnosis of Compressive Myelopathy at the Thoracolumbar Junction.

PURPOSE: The disc level in the thoracolumbar junction at which measurement of the central motor conduction time in the lower limbs (CMCT-LL) is useful for a diagnosis remains unclear. Therefore, this study investigated the spinal vertebral level at which compressive myelopathy due to ossification of the ligamentum flavum in the thoracolumbar junction is detectable using CMCT-LL. METHODS: We preoperatively measured CMCT-LL in 57 patients (42 men, 15 women; aged 35-85 years) with a single ossification of the ligamentum flavum from the T10-11 to T12-L1 disc levels and in 53 healthy controls. Motor evoked potentials after transcranial magnetic stimulation, compound muscle action potentials, and F waves were recorded from the abductor hallucis. Central motor conduction time in the lower limbs was calculated as follows: Motor evoked potential latency - (compound muscle action potential latency + F latency - 1)/2 (ms). Central motor conduction time in the lower limbs was compared between patients and controls. RESULTS: Compressive lesions were located at the T10 to 11 level in 27 patients, the T11 to 12 level in 28, and the T12-L1 level in 2. Central motor conduction time values in the lower limbs at the T10 to 11 level (19.9 ± 4.7 ms) and T11 to 12 level (18.1 ± 3.4 ms) were significantly longer than control values (11.8 ± 1.1 ms; P < 0.01). Central motor conduction time in the lower limbs was not calculated at the T12-L1 level because motor evoked potentials were not recorded in any patient. CONCLUSIONS: We confirmed that CMCT-LL was significantly longer in patients with ossification of the ligamentum flavum at the T10 to 11 and T11 to 12 levels because the S2 segment of the spinal cord is caudal at the T12 vertebral body level. Therefore, CMCT-LL is useful for diagnosing thoracolumbar junction disorders proximal to the T12 vertebral body level.

Quantitative evaluation of the biomechanical and viscoelastic properties of the dog patellar tendon in response to neuromuscular blockade at different stifle angles.

The patellar tendon (PT) is crucial for maintaining stability and facilitating movement in the stifle joint. Elastography has been recognized as a prominent method for evaluating PT properties in humans and dogs. The utilization of oscillation methods in canine studies remains limited despite their extensive documentation in human studies. Our study represents the first effort to quantitatively assess and compare the effects of muscle relaxant on the biomechanical and viscoelastic characteristics of the PT at varying stifle angles in living dogs. Five healthy female beagles were used in this study. Biomechanical (tone, stiffness, and decrement) and viscoelastic (relaxation time and creep) properties of the PT were measured using MyotonPRO (Myoton Ltd, Estonia) prior to and following administration of rocuronium (0.5 mg/kg/body weight) at normal, extended, and flexed positions. Rocuronium was selected for its safety, controllability, and widespread clinical use in veterinary anesthesia. Two-way analysis of variance showed that tone, stiffness, and decrement were significantly higher (P < 0.001) in the control group than in the muscle relaxation group. At the same time, relaxation time and creep were significantly lower (P < 0.001) in the control group than in the muscle relaxation group. The findings indicate that stifle angle position and muscle rexalant administration fundamentally alter the biomechanical loading conditions of the PT, leading to changes in its viscoelastic properties. Therefore, this novel quantitative data could benefit clinical settings that necessitate accurate and objective methods for risk identification and monitoring PT biomechanics in dogs.

Finite Element Modeling for Biomechanical Comparisons of Multilevel Transforaminal, Posterior, and Lateral Lumbar Approaches to Interbody Fusion Augmented with Posterior Instrumentation.

OBJECTIVE: Verifying the intervertebral stability of each intervertebral fusion procedure, including transforaminal, posterior, and lateral lumbar interbody fusion (TLIF, PLIF, and LLIF, respectively), and the ratio of stress on the rods and pedicle screws during initial fixation may help select a fixation procedure that reduces the risk of mechanical complications, including rod fracture and screw loosening. Thus, we aimed to assess whether these procedures could prevent mechanical complications. METHODS: Using the finite element method (FEM), we designed 4 surgical models constructed from L2-5 as follows: posterior lumbar fusion (PLF), TLIF, PLIF, and LLIF models. Bilateral rods and each pedicle screw stress were tracked and calculated as Von Mises stress (VMS) for comparison among the PLF and other 3 interbody fusion models during flexion, extension, and side-bending movements. RESULTS: The lowest rod VMS was LLIF, followed by PLIF, TLIF, and PLF in flexion and side bending movements. Compared with PLF, intervertebral fixation significantly reduced stress on the rods. No remarkable differences were observed in extension movements in each surgical procedure. A tendency for higher pedicle screw VMS was noted at the proximal and distal ends of the fixation ranges, including L2 and L5 screws for each procedure in all motions. Intervertebral fixation significantly reduced stress on the L2 and L5 screws, particularly in LLIF. CONCLUSIONS: Stress on the rods and pedicle screws in the LLIF model was the lowest compared with that induced by other intervertebral fusion procedures. Therefore, LLIF may reduce mechanical complications occurrence, including rod fracture and screw loosening.

Pediatric Spinal Giant Cell-rich Osteosarcoma: Case Report and Brief Literature Review.

BACKGROUND: Osteosarcoma, the most common primary malignant bone tumor in childhood, very rarely occurs in the spine. Criteria of complete tumor resection/stable reconstruction of osteosarcoma and the latest protocol of neoadjuvant chemotherapy of the spine have not been reported because of its rarity, technical difficulties, and its continued severe surgical risk. CASE REPORT: A 11-year-old female complained of back pain for several months and walking disability. The workup discovered a large destructive bone lesion in the thoracic 12th (Th12) with vertebral body collapse and subluxation, large amount of associated anteroposterior soft tissue components, and narrowing of the spinal canal. Histology at the 1st decompression and emergent instrumentation surgery revealed giant cell-rich osteosarcoma. Following the 1st surgery, we performed three cycles of neoadjuvant chemotherapy based on the osteosarcoma 95J (NECO95J) protocol and evaluated efficacy of chemotherapy on the Th12 tumor. The tumor was isolated only to Th12 spine following chemotherapy. Therefore, following vascular embolization of the Th12 tumor, we performed surgical resection by single posterior approach that included total en bloc spondylectomy (TES). She recovered well postoperatively, without motor or sensory deficit and no back pain. Six cycles of postoperative neoadjuvant chemotherapy were administered after the 2nd surgery and TES. The patient was disease-free at the 8-months clinical and radiological follow-up and showed no neurological involvement at 8-months. CONCLUSION: We reported a case of pediatric spinal osteosarcoma, the surgical technique of complete tumor resection, and stable reconstruction of spinal osteosarcoma. We also discussed the recent neoadjuvant chemotherapy protocol for osteosarcoma.

Reference intervals and sources of variation of pressure pain threshold for quantitative sensory testing in a Japanese population.

Quantitative sensory testing (QST) is useful when analysing musculoskeletal pain disorders. A handheld algometer is most commonly used for pressure pain threshold (PPT) tests. However, reference intervals for PPTs are not elucidated. We assessed reference intervals of PPTs for QST in 158 healthy adult Japanese with no history of musculoskeletal or neurological problems. A handheld algometer was used to record PPT at five different assessment sites on the body: lumbar paravertebral muscle, musculus gluteus maximus, quadriceps, tibialis anterior muscle, and anterior talofibular ligament. Multiple regression analysis was performed to explore sources of variation of PPT according to sex, age, body mass index, UCLA Activity Level Rating, and Tegner Activity Score. Reference intervals were determined parametrically by Gaussian transformation of PPT values using the two-parameter Box-Cox formula. Results of multiple regression analysis revealed that age was significantly associated with PPT of lumbar paravertebral muscle and musculus gluteus maximus. In females, body mass index showed significant positive correlation with PPT of anterior talofibular ligament, and UCLA Activity Level Rating also showed significant positive association with tibialis anterior muscle and anterior talofibular ligament. Site-specific reference intervals of PPTs for Japanese are of practical relevance in fields of pain research using a handheld algometer.

Posterior Fixation for Different Thoracic-Sacrum Alignments Containing a Thoracolumbar Vertebral Fracture: A Finite Element Analysis.

OBJECTIVE: Thoracolumbar vertebral fractures are one of the most common fractures; however, there is a lack of mechanical analyses for what the posterior fixation is for different spine alignments. METHODS: This study used a three-dimensional finite element model of a T1-sacrum. Three alignment models were created: intact, degenerative lumbar scoliosis (DLS), and adolescent idiopathic scoliosis (AIS). The burst fracture was assumed to be at the L1 vertebral level. Posterior fixation models with pedicle screws (PS) were constructed for each model: 1 vertebra above to 1 below PS (4PS) and 1 vertebra above to 1 below PS with additional short PS at the L1 (6PS); intact-burst-4PS, intact-burst-6PS, DLS-burst-4PS, DLS-burst-6PS, AIS-burst-4PS, and AIS-burst-6PS models. T1 was loaded with a moment of 4 Nm assuming flexion and extension. RESULTS: The vertebrae stress varied with spinal alignment. The stress of L1 in intact burst (IB), DLS burst, and AIS burst increased by more than 190% compared with each nonfractured model. L1 stress in IB, DLS, and AIS-4PS increased to more than 47% compared with each nonfractured model. L1 stress in IB, DLS, and AIS-6PS increased to more than 25% compared with each nonfractured model. In flexion and extension, stress on the screws and rods of intact-burst-6PS, DLS-6PS, and AIS-6PS was lower than in the intact-burst-4PS, DLS-4PS, and AIS-4PS models. CONCLUSIONS: It may be more beneficial to use 6PS compared with 4PS to reduce stresses on the fractured vertebrae and instrumentation, regardless of the spinal alignment.

Preoperative Symptom Duration Influences Neurological Recovery and Patient-Reported Outcome Measures After Surgical Treatment of Cervical Ossification of the Posterior Longitudinal Ligament.

STUDY DESIGN: A prospective multicenter study. OBJECTIVE: To investigate the effect of preoperative symptom duration on neurological recovery for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA: The optimal timing to perform surgery in the setting of cervical OPLL remains unknown. It is important to know the influence of symptom duration on postoperative outcomes to facilitate discussions regarding the timing of surgery. PATIENTS AND METHODS: The study included 395 patients (291 men and 104 women; mean age, 63.7 ± 11.4 yr): 204 were treated with laminoplasty, 90 with posterior decompression and fusion, 85 with anterior decompression and fusion, and 16 with other procedures. The Japanese Orthopedic Association (JOA) score and patient-reported outcomes of the JOA Cervical Myelopathy Evaluation Questionnaire were used to assess clinical outcomes preoperatively and 2 years after surgery. Logistic regression analysis was used to identify factors associated with the achievement of minimum clinically important difference (MCID) after surgery. RESULTS: The recovery rate was significantly lower in the group with symptom duration of ≥5 years compared with the groups with durations of <0.5 years, 0.5 to 1 year, and 1 to 2 years. Improvement of JOA Cervical Myelopathy Evaluation Questionnaire in the upper extremity function score ( P < 0.001), lower extremity function ( P = 0.039), quality of life ( P = 0.053), and bladder function ( P = 0.034) were all decreased when the symptom duration exceeded 2 years. Duration of symptoms ( P = 0.001), age ( P < 0.001), and body mass index ( P < 0.001) were significantly associated with the achievement of MCID. The cutoff value we established for symptom duration was 23 months (area under the curve, 0.616; sensitivity, 67.4%; specificity, 53.5%). CONCLUSIONS: Symptom duration had a significant impact on neurological recovery and patient-reported outcome measures in this series of patients undergoing surgery for cervical OPLL. Patients with symptom duration exceeding 23 months may be at greater risk of failing to achieve MCID after surgery. LEVEL OF EVIDENCE: 3.

The Effect of Posterior Lumbar Interbody Fusion in Lumbar Spine Stenosis with Diffuse Idiopathic Skeletal Hyperostosis: A Finite Element Analysis.

OBJECTIVE: Lumbar spinal canal stenosis (LSS) with diffuse idiopathic skeletal hyperostosis (DISH) can require revision surgery because of the intervertebral instability after decompression. However, there is a lack of mechanical analyses for decompression procedures for LSS with DISH. METHODS: This study used a validated, three-dimensional finite element model of an L1-L5 lumbar spine, L1-L4 DISH, pelvis, and femurs to compare the biomechanical parameters (range of motion [ROM], intervertebral disc, hip joint, and instrumentation stresses) with an L5-sacrum (L5-S) and L4-S posterior lumbar interbody fusion (PLIF). A pure moment with a compressive follower load was applied to these models. RESULTS: ROM of L5-S and L4-S PLIF models decreased by more than 50% at L4-L5, respectively, and decreased by more than 15% at L1-S compared with the DISH model in all motions. The L4-L5 nucleus stress of the L5-S PLIF increased by more than 14% compared with the DISH model. In all motions, the hip stress of DISH, L5-S, and L4-S PLIF had very small differences. The sacroiliac joint stress of L5-S and L4-S PLIF models decreased by more than 15% compared with the DISH model. The stress values of the screws and rods in the L4-S PLIF model was higher than in the L5-S PLIF model. CONCLUSIONS: The concentration of stress because of DISH may influence adjacent segment disease on the nonunited segment of PLIF. A shorter-level lumbar interbody fixation is recommended to preserve ROM; however, it should be used with caution because it could provoke adjacent segment disease.

Factors Associated With Loss of Cervical Lordosis After Laminoplasty for Patients With Cervical Ossification of the Posterior Longitudinal Ligament: Data From a Prospective Multicenter Study.

STUDY DESIGN: A prospective multicenter study. OBJECTIVE: The objective of this study was to investigate the incidence of loss of cervical lordosis after laminoplasty for cervical ossification of the posterior longitudinal ligament (OPLL). We also sought to determine associated risk factors and the relationship with patient-reported outcomes. SUMMARY OF BACKGROUND DATA: Loss of cervical lordosis is a sequelae often observed after laminoplasty, which may adversely impact surgical outcomes. Cervical kyphosis, especially in OPLL, is associated with reoperation, but risk factors and relationship to postoperative outcomes remain understudied at this time. MATERIALS AND METHODS: This study was conducted by the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. We included 165 patients who underwent laminoplasty and completed Japanese Orthopaedic Association (JOA) score or Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaires (JOACMEQ), as well as Visual Analog Scales (VAS) for pain, with imaging. The participants were divided into two groups: those with loss of cervical lordosis of >10° or 20° after surgery and those without loss of cervical lordosis. A paired t test was applied to evaluate the association between changes in cervical spinal angles, range of motion, and cervical JOA and VAS scores before and at 2 years postoperatively. Mann-Whitney U test was used for JOACMEQ. RESULTS: Postoperative loss of cervical lordosis >10° and >20° was observed in 32 (19.4%) and 7 (4.2%), respectively. JOA, JOACMEQ, and VAS scores were not significantly different between those with, and without, loss of cervical lordosis. Preoperative small extension range of motion (eROM) was significantly associated with postoperative loss of cervical lordosis, and the cutoff values of eROM were 7.4° [area under the curve (AUC): 0.76] and 8.2° (AUC: 0.92) for loss of cervical lordosis >10° and >20°, respectively. A large occupation ratio of OPLL was also associated with loss of cervical lordosis, with a cutoff value of 39.9% (AUC: 0.94). Laminoplasty resulted in functional improvement in most patient-reported outcomes; however, neck pain and bladder function tended to become worse postoperatively in cases with postoperative loss of cervical lordosis >20°. CONCLUSIONS: JOA, JOACMEQ, and VAS scores were not significantly different between those with, and without, loss of cervical lordosis. Preoperative small eROM and large OPLL may represent factors associated with loss of cervical lordosis after laminoplasty in patients with OPLL.

Factors associated with improvement in tibialis anterior weakness due to lumbar degenerative disease.

BACKGROUND: The weakness of the tibialis anterior remains to be a controversial topic. There has been no study that used electrophysiological assessment of the function of the lumbar and sacral peripheral motor nerves. The aim is to evaluate surgical outcomes in patients with weakness of the tibialis anterior using neurological and electrophysiological assessments. METHODS: We enrolled 53 patients. Tibialis anterior weakness was quantified by muscle strength, as assessed using a manual muscle test on a scale of 1 through 5, with scores <5 indicating weakness. Postoperative improvement in muscle strength was classified as excellent (5 grades recovered), good (more than one grade recovered), or fair (less than one grade recovered). RESULTS: Surgical outcomes for tibialis anterior function were categorized as "excellent" in 31, "good" in 8, "fair" in 14 patients. Significant difference in outcomes were observed depending on diabetes mellitus status, type of surgery, and the compound muscle action potentials amplitudes of the abductor hallucis and extensor digitorum brevis (p < 0.05). Surgical outcomes were classified into two groups, patients with excellent and good outcomes (Group 1) and patients with fair outcome (Group 2). Using the forward selection stepwise method, sex and the compound muscle action potentials amplitudes of the extensor digitorum brevis were identified as significant factors for their positive association with Group 1 status. The diagnostic power of the predicted probability was as high as 0.87 in terms of area under curve of the receiver operating characteristic curve. CONCLUSIONS: There was a significant correlation between the prognosis of tibialis anterior weakness and sex and the compound muscle action potentials amplitude of extensor digitorum brevis, suggesting that recording the compound muscle action potentials amplitude of extensor digitorum brevis will aid the outcome assessment of future surgical interventions for tibialis anterior weakness.