Biomechanical analysis of adjacent segments after correction surgery for adult idiopathic scoliosis: a finite element analysis.

The biomechanical aspects of adjacent segment degeneration after Adult Idiopathic Scoliosis (AdIS) corrective surgery involving postoperative changes in motion and stress of adjacent segments have yet to be investigated. The objective of this study was to evaluate the biomechanical effects of corrective surgery on adjacent segments in adult idiopathic scoliosis by finite element analysis. Based on computed tomography data of the consecutive spine from T1-S1 of a 28-year-old male patient with adult idiopathic scoliosis, a three-dimensional finite element model was established to simulate the biomechanics. Two posterior long-segment fixation and fusion operations were designed: Strategy A, pedicle screws implanted in all segments of both sides, and Strategy B, alternate screws instrumentation on both sides. The range of motion (ROM), Maximum von Mises stress value of intervertebral disc (IVD), and Maximum von Mises stress of the facet joint (FJ) at the fixation adjacent segment were calculated and compared with data of the preoperative AdIS model. Corrective surgery decreased the IVD on the adjacent segments, increased the FJ on the adjacent segments, and decreased the ROM of the adjacent segments. A greater decrease of Maximum von Mises stress was observed on the distal adjacent segment compared with the proximal adjacent segment. The decrease of Maximum von Mises stress and increment of Maximum von Mises stress on adjacent FJ in strategy B was greater than that in strategy A. Under the six operation modes, the change of the Maximum von Mises stress on the adjacent IVD and FJ was significant. The decrease in ROM in the proximal adjacent segment was greater than that of the distal adjacent segment, and the decrease of ROM in strategy A was greater than that in strategy B. This study clarified the biomechanical characteristics of adjacent segments after AdIS corrective surgery, and further biomechanical analysis of two different posterior pedicle screw placement schemes by finite element method. Our study provides a theoretical basis for the pathogenesis, prevention, and treatment of adjacent segment degeneration after corrective surgery for AdIS.

Trabecular bone mineral density as measured by thoracic vertebrae predicts incident hip and vertebral fractures: the multi-ethnic study of atherosclerosis.

We evaluated the relationship of bone mineral density (BMD) by computed tomography (CT), to predict fractures in a multi-ethnic population. We demonstrated that vertebral and hip fractures were more likely in those patients with low BMD. This is one of the first studies to demonstrate that CT BMD derived from thoracic vertebrae can predict future hip and vertebral fractures. PURPOSE/INTRODUCTION: Osteoporosis affects an enormous number of patients, of all races and both sexes, and its prevalence increases as the population ages. Few studies have evaluated the association between the vertebral trabecular bone mineral density(vBMD) and osteoporosis-related hip fracture in a multiethnic population, and no studies have demonstrated the predictive value of vBMD for fractures. METHOD: We sought to determine the predictive value of QCT-based trabecular vBMD of thoracic vertebrae derived from coronary artery calcium scan for hip fractures in the Multi-Ethnic Study of Atherosclerosis(MESA), a nationwide multicenter cohort included 6814 people from six medical centers across the USA and assess if low bone density by QCT can predict future fractures. Measures were done using trabecular bone measures, adjusted for individual patients, from three consecutive thoracic vertebrae (BDI Inc, Manhattan Beach CA, USA) from non-contrast cardiac CT scans. RESULTS: Six thousand eight hundred fourteen MESA baseline participants were included with a mean age of 62.2 ± 10.2 years, and 52.8% were women. The mean thoracic BMD is 162.6 ± 46.8 mg/cm3 (95% CI 161.5, 163.7), and 27.6% of participants (n = 1883) had osteoporosis (T-score 2.5 or lower). Over a median follow-up of 17.4 years, Caucasians have a higher rate of vertebral fractures (6.9%), followed by Blacks (4.4%), Hispanics (3.7%), and Chinese (3.0%). Hip fracture patients had a lower baseline vBMD as measured by QCT than the non-hip fracture group by 13.6 mg/cm3 [P < 0.001]. The same pattern was seen in the vertebral fracture population, where the mean BMD was substantially lower 18.3 mg/cm3 [P < 0.001] than in the non-vertebral fracture population. Notably, the above substantial relationship was unaffected by age, gender, race, BMI, hypertension, current smoking, medication use, or activity. Patients with low trabecular BMD of thoracic vertebrae showed a 1.57-fold greater risk of first hip fracture (HR 1.57, 95% CI 1.38-1.95) and a nearly threefold increased risk of first vertebral fracture (HR 2.93, 95% CI 1.87-4.59) compared to normal BMD patients. CONCLUSION: There is significant correlation between thoracic trabecular BMD and the incidence of future hip and vertebral fracture. This study demonstrates that thoracic vertebrae BMD, as measured on cardiac CT (QCT), can predict both hip and vertebral fractures without additional radiation, scanning, or patient burden. Osteopenia and osteoporosis are markedly underdiagnosed. Finding occult disease affords the opportunity to treat the millions of people undergoing CT scans every year for other indications.

Efficacy analysis of one-stage posterior-only surgical treatment for thoracic spinal tuberculosis in the T4-6 segments with minimum 5-year follow-up.

In recent years, with the in-depth research on spinal tuberculosis, posterior surgery alone has been praised highly by more and more surgeons due to the better correction of kyphosis, better maintenance of spinal physiological curvature, smaller surgical trauma and fewer surgical complications. However, there is currently lack of relevant reports about the efficacy of posterior surgery alone in the treatment of tuberculosis in the T4-6 segments. This study aimed to evaluate the clinical study efficacy and feasibility of one-stage posterior-only surgical treatment for thoracic spinal tuberculosis in the T4-6 segments. 67 patients with tuberculosis in T4-6 segments who underwent one-stage posterior-only surgery were included in this study. The clinical efficacy was evaluated using statistical analysis based on the data about erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Oswestry Dability Index (ODI) score, Visual Analogue Scale (VAS) score and Cobb angle before surgery, after surgery and at the last follow-up. All patients completed fusion during the follow-up period of 6-9 months. ESR and CRP were returned to normal for all patients at 6 months follow-up. In the meanwhile, among the 27 patients combined with neurological impairment, neurological functions of 22 cases (81.48%) recovered completely at the last follow-up (P < 0.05). Cobb angle of the kyphosis was improved from preoperative 34.8 ± 10.9° to postoperative 9.6 ± 2.8°, maintaining at 11.3 ± 3.2° at the last follow-up, The ODI and VAS scores were improved by 77.10% and 81.70%, respectively. This 5-year follow-up study shows that better clinical efficacy can be achieved for tuberculosis in T4-6 segments using one-stage posterior-only approach by costotransverse debridement in combination with bone graft and internal fixation. The posterior surgical method cannot only effectively accomplish debridement, obtain satisfactory clinical results, but also well correct kyphotic deformity and maintain it.

Correlation of Acetabular Anteversion and Thoracic Kyphosis Postoperatively with Proximal Junctional Failure in Adult Spinal Deformity Fused to Pelvis.

OBJECTIVES: To investigate whether the immediate thoracic kyphosis (TK) and acetabular anteversion (AA) postoperatively are correlated with proximal junctional failure (PJF) in adult spinal deformity (ASD) patients underwent surgical treatment. METHODS: This is a retrospective study. Following institutional ethics approval, a total of 57 patients (49 Female, eight Male) with ASD underwent surgery fused to sacroiliac bone (S1, S2, or ilium) from March 2014 to January 2019 were included. All of those patients were followed up for at least 2 years. Demographic, radiographic and surgical data were recorded. The maximum range of flexion motion (F-ROM) and extension motion (E-ROM) actively of hip joints was measured and recorded at pre- and postoperation. The sum of F-ROM and E-ROM was defined as the range of hip motion (H-ROM). Receiver operating characteristic (ROC) curve analysis was used to obtain the cut off value of parameters for PJF. A Kaplan-Meier curve and log-rank test were used to analyze the differences in PJF-free survival. RESULTS: In all, 14 patients developed PJF during follow-up. Comparisons between patients with and without PJF showed significant differences in immediate TK (P < 0.001) and AA (P = 0.027) postoperatively. ROC curve analysis determined an optimal threshold of 13° for immediate AA postoperatively (sensitivity = 74.3%, specificity = 85.7%, area under the ROC curve [AUC] = 0.806, 95% CI [0.686-0.926]). Nineteen patients with post-AA ≤13° were assigned into the observational group, and 38 patients with post-AA >13° were being as the control group. Patients in the observational group had smaller H-ROM (P = 0.016) and F-ROM (P < 0.001), but much larger E-ROM (P < 0.001). There were 10 patients showing PJF in the observational group and four in the control group (10/9 vs 4/34, P < 0.001). PJF-free survival time significantly decreased in the observational group (P = 0.001, log-rank test). Furthermore, patients in the observational group had much larger TK (post-TK, P = 0.015). The optimal threshold for post-TK (sensitivity = 85.7%, specificity = 76.7%; AUC = 0.823, 95% CI [0.672-0.974]) was 28.1° after the ROC curve was analyzed. In the observational group, those patients with post-TK ≥28.1° had significantly higher incidence of PJF (9/2 vs 1/7, P < 0.001) than those with post-TK < 28.1°. Moreover, PJF-free survival time in those patients significantly decreased (P = 0.001, log-rank test). CONCLUSIONS: ASD patients with acetabular anteversion of ≤13° at early postoperation may suffer significantly restricted hip motion and much higher incidence of PJF during follow-up, moreover, in those patients, postoperative TK ≥28.1° would be a significant risk factor for PJF developing.

Large Lytic Defects Produce Kinematic Instability and Loss of Compressive Strength in Human Spines: An in Vitro Study.

BACKGROUND: In patients with spinal metastases, kinematic instability is postulated to be a predictor of pathologic vertebral fractures. However, the relationship between this kinematic instability and the loss of spinal strength remains unknown. METHODS: Twenty-four 3-level thoracic and lumbar segments from 8 cadaver spines from female donors aged 47 to 69 years were kinematically assessed in axial compression (180 N) and axial compression with a flexion or extension moment (7.5 Nm). Two patterns of lytic defects were mechanically simulated: (1) a vertebral body defect, corresponding to Taneichi model C (n = 13); and (2) the model-C defect plus destruction of the ipsilateral pedicle and facet joint, corresponding to Taneichi model E (n = 11). The kinematic response was retested, and compression strength was measured. Two-way repeated-measures analysis of variance was used to test the effect of each model on the kinematic response of the segment. Multivariable linear regression was used to test the association between the kinematic parameters and compressive strength of the segment. RESULTS: Under a flexion moment, and for both models C and E, the lesioned spines exhibited greater flexion range of motion (ROM) and axial translation than the control spines. Both models C and E caused lower extension ROM and greater axial, sagittal, and transverse translation under an extension moment compared with the control spines. Two-way repeated-measures analysis revealed that model E, compared with model C, caused significantly greater changes in extension and torsional ROM under an extension moment, and greater sagittal translation under a flexion moment. For both models C and E, greater differences in flexion ROM and sagittal translation under a flexion moment, and greater differences in extension ROM and in axial and transverse translation under an extension moment, were associated with lower compressive strength of the lesioned spines. CONCLUSIONS: Critical spinal lytic defects result in kinematic abnormalities and lower the compressive strength of the spine. CLINICAL RELEVANCE: This experimental study demonstrates that lytic foci degrade the kinematic stability and compressive strength of the spine. Understanding the mechanisms for this degradation will help to guide treatment decisions that address inferred instability and fracture risk in patients with metastatic spinal disease.

Biomechanical finite element analysis of vertebral column resection and posterior unilateral vertebral resection and reconstruction osteotomy.

BACKGROUND: Regarding the repair of vertebral compression fractures, there is a lack of adequate biomechanical verification as to whether only half of the vertebral body and the upper and lower intervertebral discs affect spinal biomechanics; there also remains debate as to the appropriate length of fixation. METHODS: A model of old vertebral compression fractures with kyphosis was established based on CT data. Vertebral column resection (VCR) and posterior unilateral vertebral resection and reconstruction (PUVCR) were performed at T12; long- and short-segment fixation methods were applied, and we analyzed biomechanical changes after surgery. RESULTS: Range of motion (ROM) decreased in all fixed models, with lumbar VCR decreasing the most and short posterior unilateral vertebral resection and reconstruction (SPUVCR) decreasing the least; in the long posterior unilateral vertebral resection and reconstruction (LPUVCR) model, the internal fixation system produced the maximum VMS stress of 213.25 mPa in a lateral bending motion and minimum stress of 40.22 mPa in a lateral bending motion in the SVCR. CONCLUSION: There was little difference in thoracolumbar ROM between PUVCR and VCR models, while thoracolumbar ROM was smaller in long-segment fixation than in short-segment fixation. In all models, the VMS was most significant at the screw-rod junction and greatest at the ribcage-vertebral body interface, partly explaining the high probability of internal fixation failure and prosthesis migration in these two positions.

Takotsubo syndrome triggered by change in position in a patient with thoracic vertebral fracture: A case report.

RATIONALE: Takotsubo syndrome (TTS) is characterized by recovery of wall motion abnormalities and acute left ventricular dysfunction, which are often caused by acute physical or emotional stressors. It is rarely reported that TTS can be precipitated by change in position in the patient in the operating room. We report a case of a patient with a thoracic vertebral fracture who presented with TTS precipitated by changing from a supine to a prone position before percutaneous kyphoplasty (PKP) under local anesthesia. PATIENT CONCERNS: A 76-year-old man who was diagnosed with a fracture in a thoracic vertebra was sent to the operating room to undergo PKP under local anesthesia. Approximately 5 minutes after changing from a supine to a prone position, which is necessary for PKP, the patient experienced chest pain, headache, and sweating. DIAGNOSIS: A fracture in a thoracic vertebra; TTS. INTERVENTIONS: As a result of 12-lead electrocardiography, echocardiography, left ventriculogram, and cardiac catheterization, the diagnosis of TTS was retained, and supportive therapy was initiated. OUTCOMES: Two hours later, the patient's symptoms mitigated significantly and the ST segment returned to baseline. Four days later, echocardiography showed normal systolic function without wall motion abnormalities and the patient returned to the orthopedics ward for further treatment. LESSONS: It is necessary for anesthetists to recognize TTS which is life-threatening during monitored anesthetic care (MAC). We highlight the importance of being alerted to the possibility of TTS when managing patients with thoracic vertebral fractures undergoing surgery under local anesthesia.

Efficacy of Intraoperative Intervention Following Transcranial Motor-evoked Potentials Alert During Posterior Decompression and Fusion Surgery for Thoracic Ossification of the Posterior Longitudinal Ligament: A Prospective Multicenter Study of the Monitoring Committee of the Japanese Society for Spine Surgery and Related Research.

STUDY DESIGN: Prospective, multicenter, observational study. OBJECTIVE: The aim of this study was to investigate the efficacy of intervention after an alert in intraoperative neurophysiological monitoring (IONM) using transcranial motor-evoked potentials (Tc-MEPs) during surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL). SUMMARY OF BACKGROUND DATA: T-OPLL is commonly treated with posterior decompression and fusion with instrumentation. IONM using Tc-MEPs during surgery reduces the risk of neurological complications. METHODS: The subjects were 79 patients with a Tc-MEP alert during posterior decompression and fusion surgery for T-OPLL. Preoperative muscle strength (manual muscle testing [MMT]), waveform derivation rate at the start of surgery (baseline), intraoperative waveform changes; and postoperative motor paralysis were examined. A reduction in MMT score of ≥1 on the day after surgery was classified as worsened postoperative motor deficit. An alert was defined as a decrease in Tc-MEP waveform amplitude of ≥70% from baseline. Alerts were recorded at key times during surgery. RESULTS: The patients (35 males, 44 females; age 54.6 years) had OPLL at T1-4 (n = 27, 34%), T5-8 (n = 50, 63%), and T9-12 (n = 16, 20%). The preoperative status included sensory deficit (n = 67, 85%), motor deficit (MMT ≤4) (n = 59, 75%), and nonambulatory (n = 26, 33%). At baseline, 76 cases (96%) had a detectable Tc-MEP waveform for at least one muscle, and the abductor hallucis had the highest rate of baseline waveform detection (n = 66, 84%). Tc-MEP alerts occurred during decompression (n = 47, 60%), exposure (n = 13, 16%), rodding (n = 5, 6%), pedicle screw insertion (n = 4, 5%), posture change (n = 4, 5%), dekyphosis (n = 2, 3%), and other procedures (n = 4, 5%). After intraoperative intervention, the rescue rate (no postoperative neurological deficit) was 57% (45/79), and rescue cases had a significantly better preoperative ambulatory status and a significantly higher baseline waveform derivation rate. CONCLUSION: These results show the efficacy of intraoperative intervention following a Tc-MEP alert for prevention of neurological deficit postoperatively.Level of Evidence: 2.

Comparison of Anterior and Posterior Decompressions in Treatment of Traumatic Thoracolumbar Spinal Fractures Complicated with Spinal Cord Injury.

BACKGROUND For patients with thoracolumbar spinal fractures complicated with spinal cord injury, timely surgery is the first choice. We compared the effects of anterior and posterior decompressions in treatment of these patients. MATERIAL AND METHODS A total of 80 male patients with traumatic thoracolumbar spinal fractures and spinal cord injury were prospectively selected and divided into 2 groups. The control group underwent posterior decompression and internal fixation and the observation group underwent real-time anterior decompression. RESULTS The observation group had longer operative time and length of postoperative hospital stay, larger intraoperative blood loss, remarkably greater immediate postoperative anterior height and middle column height of the fractured vertebrae, and a notably smaller Cobb's angle than in the control group. The total ASIA score was significantly higher in the observation group than in the control group immediately after surgery and at 6 months and 1 year after surgery. The maximal urine flow, maximal detrusor pressure, and bladder compliance were also evidently higher in the observation group than in the control group during 1 year of follow-up. Compared with the control group, the International Index of Erectile Function-5 (IIEF-5) score in the observation group was significantly higher at 3 months, 6 months, and 1 year after surgery. CONCLUSIONS Compared with the posterior approach, anterior decompression in patients with thoracolumbar spinal fractures complicated with spinal cord injury can effectually enhance the surgical efficiency, and restore the physiological anatomy of the fractured vertebrae, thereby improving patient quality of life.

How the clinical dosage of bone cement biomechanically affects adjacent vertebrae.

OBJECTIVE: This study evaluated the biomechanical changes in the adjacent vertebrae under a physiological load (500 N) when the clinically relevant amount of bone cement was injected into fractured cadaver vertebral bodies. METHODS: The embalmed cadaver thoracolumbar specimens in which each vertebral body (T12-L2) had a BMD of < 0.75 g/cm2 were used for the experiment. For establishing a fracture model, the upper one third of the L1 vertebra was performed wedge osteotomy and the superior endplate was kept complete. Stiffness of specimens was measured in different states. Strain of the adjacent vertebral body and intervertebral disc were measured in pre-fracture, post-fracture, and after augmentation by non-contact optical strain measurement system. RESULTS: The average amount of bone cement was 4.4 ml (3.8-5.0 ml). The stiffness of after augmentation was significantly higher than the stiffness of post-fracture (p < 0.05), but still lower than pre-fracture stiffness (p < 0.05). After augmentation, the adjacent upper vertebral strain showed no significant difference (p > 0.05) with pre-fracture, while the strain of adjacent lower vertebral body was significantly higher than that before fracture (p < 0.05). In flexion, T12/L1 intervertebral disc strain was significantly greater after augmentation than after the fracture (p < 0.05), but there was no significant difference from that before the fracture (p > 0.05); L1/2 vertebral strain after augmentation was significantly less than that after the fracture (p < 0.05), but there was no significant difference from that before the fracture (p > 0.05). CONCLUSIONS: PVP may therefore have partially reversed the abnormal strain state of adjacent vertebral bodies which was caused by fracture.

Tricortical iliac crest allograft with anterolateral single rod screw instrumentation in the treatment of thoracic and lumbar spinal tuberculosis.

To assess the effectiveness of tricortical iliac crest allografts with anterolateral instrumentation after single-stage surgery for thoracic and lumbar spinal tuberculosis (TB). Fifty-six patients with thoracic and lumbar spinal TB underwent single-stage anterior radical debridement, interbody fusion with tricortical iliac crest allografts and anterolateral single rod instrumentation. All patients were given 18 months of antituberculosis chemotherapy. The patients were followed up regularly, and their clinical manifestations, roentgenogram results, erythrocyte sedimentation rate (ESR) and liver function test were the results to be concerned. Radiographs were analysed before surgery, immediately after surgery, and at the final follow-up examination. Mean follow-up period was 37.5 months in 52 patients, and 4 patients were lost to follow-up. No patients had superficial wound infections, and all the incisions healed within 2 weeks. No graft fracture, collapse, or sliding was observed. The average bony fusion time was 10.6 months. Bony fusion was observed in all 52 patients within 18 months. The average degrees of kyphotic correction loss for thoracic and lumbar spine were 6.71° and 2.78° respectively. Although it took a long time to achieve solid fusion, tricortical iliac crest allografts were found to be convenient and safe to be used in spinal TB surgery. They may be effective options for interbody fusion, deformity correction and correction maintenance with anterolateral single rod instrumentation.

[Chest deformity as a cause of tracheobronchial compression. A pediatric case]. / Deformidad torácica como causa de compresión traqueobronquial. A propósito de un caso clínico pediátrico.

Idiopathic scoliosis is the abnormal flexion and rotation of the vertebral bodies, causing respiratory symptoms and altered pulmonary function. Straight back syndrome is a decreased in the anteroposterior diameter of the thorax. We present a 13-year-old patient with idiopathic scoliosis who Deformidad torácica como causa de compresión traqueobronquial. A propósito de un caso clínico pediátrico Chest deformity as a cause of tracheobronchial compression. A pediatric case developed progressive dyspnea, inspiratory stridor and a significant decrease in pulmonary function, because of extrinsic compression of the right main bronchus and the middle third of trachea by the thoracic vertebral bodies. She had also a decreased anteroposterior diameter of the thorax, being a determining factor in the appearance of symptoms. Surgery was performed by thoracic vertebra fixation T3 to T11, with subsequent clinical and functional respiratory improvement. Scoliosis associated with altered pulmonary function and stridor should make us suspect the existence of airway compression, especially in patients with reduction of the anteroposterior diameter of the thorax.

La escoliosis idiopática es la flexión y rotación anómala de los cuerpos vertebrales, que puede causar sintomatología respiratoria y alteración de función pulmonar. El síndrome de la espalda recta es una alteración caracterizada por una disminución del diámetro anteroposterior del tórax. Se presenta a una paciente de 13 años afectada de escoliosis idiopática que desarrolló disnea de esfuerzo progresiva, estridor inspiratorio y disminución importante de función pulmonar, secundaria a compresión extrínseca del bronquio principal derecho y tercio medio traqueal por cuerpos vertebrales torácicos. A su vez, tenía una disminución del diámetro anteroposterior del tórax, factor determinante en la aparición de los síntomas. Se intervino mediante fijación de vértebra torácica T3-T11, con posterior mejoría clínica y funcional respiratoria. La escoliosis asociada a alteración de función pulmonar y estridor debe hacer sospechar la existencia de compresión de la vía aérea, especialmente, en pacientes con reducción del diámetro anteroposterior del tórax.

Essential lordosis revisited.

AIMS: Significant correction of an adolescent idiopathic scoliosis in the coronal plane through a posterior approach is associated with hypokyphosis. Factors such as the magnitude of the preoperative coronal curve, the use of hooks, number of levels fused, preoperative kyphosis, screw density, and rod type have all been implicated. Maintaining the normal thoracic kyphosis is important as hypokyphosis is associated with proximal junctional failure (PJF) and early onset degeneration of the spine. The aim of this study was to determine if coronal correction per se was the most relevant factor in generating hypokyphosis. METHODS: A total of 95 patients (87% female) with a median age of 14 years were included in our study. Pre- and postoperative radiographs were measured and the operative data including upper instrumented vertebra (UIV), lower instrumented vertebra (LIV), metal density, and thoracic flexibility noted. Further analysis of the post-surgical coronal outcome (group 1 < 60% correction and group 2 ≥ 60%) were studied for their association with the postoperative kyphosis in the sagittal plane using univariate and multivariate logistic regression. RESULTS: Of the 95 patients, 71.6% (68) had a thoracic correction of > 60%. Most (97.8%) had metal density < 80%, while thoracic flexibility > 50% was found in 30.5% (29). Preoperative hypokyphosis (< 20°) was present in 25.3%. A postoperative thoracic hypokyphosis was four times more likely to occur in patients with thoracic correction ≥ 60% (odds ratio (OR) 4.08; p = 0.005), after adjusting for confounding variables. This association was not affected by metal density, thoracic flexibility, LIV, UIV, age, or sex. CONCLUSION: Our study supports the 'essential lordosis' hypothesis of Roaf and Dickson, i.e. with a greater ability to translate the apical vertebra towards the midline, there is a commensurate lengthening of the anterior column due to the vertebral wedging. Cite this article: Bone Joint J 2020;102-B(4):513-518.

Cortical Bone Trajectory Instrumentation with Vertebroplasty for Osteoporotic Thoracolumbar Compression Fracture.

BACKGROUND: Osteoporotic spinal fractures commonly occur in elderly patients with low bone mineral density. In these cases, percutaneous vertebroplasty or percutaneous kyphoplasty can provide significant pain relief and improve mobility. However, studies have reported both the recurrence of vertebral compression fractures at the index level after vertebroplasty and the development of new vertebral fractures at the adjacent level that occur without any additional trauma. Pedicle screw fixation combined with percutaneous vertebroplasty has been proposed as an effective procedure for addressing osteoporotic thoracolumbar fractures. However, in osteoporotic populations, pedicle screws can loosen, pullout, or migrate. Currently, the efficacy of cortical bone trajectory screw fixation for osteoporotic fractures remains unclear. Thus, we assessed the effects of using cortical bone trajectory instrumentation with vertebroplasty on patient outcomes. METHOD: We retrospectively reviewed data from 12 consecutively sampled osteoporotic thoracolumbar fracture patients who underwent cortical bone trajectory instrumentation with vertebroplasty. Patients were enrolled beginning in October 2015 and were followed for >24 months. RESULT: The average age was 74 years, and the average dual-energy x-ray absorptiometry T-score was -3.6. The average visual analog scale pain scores improved from 8 to 2.5 after surgery. The average blood loss was 36.25 mL. All patients regained ambulation and experienced reduced pain post-surgery. No recurrent fractures or instrument failures were recorded during follow-up. CONCLUSIONS: Our findings suggest that cortical bone trajectory instrumentation combined with percutaneous vertebroplasty may be a good option for treating osteoporotic thoracolumbar fractures, as it can prevent recurrent vertebral fractures or related kyphosis in sagittal alignment.

Physiotherapeutic management of a patient with spinal Schwannoma: A case report.

INTRODUCTION: Tumors are generally considered as red flags to manual therapy. The purpose of this report is to describe the clinical course of a patient diagnosed with spinal Schwannoma at L2-L3 level, who was referred to physiotherapy (PT) for the treatment of low back pain radiating to the left lower limb. CASE DESCRIPTION: A 30-year old man previously diagnosed with L2-L3 Schwannoma was referred for physiotherapy for the treatment of radiating pain. The patient had not responded favorably to symptomatic management. As the patient's history and physical examination were consistent with a mechanical dysfunction, it was decided to manage the patient along similar lines. The patient was treated with McKenzie extension and central postero-anterior mobilization over T4-T6 vertebrae. This intervention was followed up with strengthening and aerobic exercises. RESULTS: The outcomes were measured by the numerical rating scale (NRS), Oswestry Disability Index (ODI) and the Global rate of Change (GRC) scale. The patient responded well to McKenzie extension exercises and Thoracic mobilization. The NRS (7 at rest; 10 on activity) at the time of referral reduced to (2 on activity) at the time of discharge. The outcomes were maintained after 7 months. CONCLUSION: This case suggests that there is a need to undertake a detailed musculoskeletal examination and mobilization may be safely performed in patients diagnosed with spinal schwannomas. An individualized tailored approach may be beneficial in these patients.

Biomechanical cadaver study of proximal fixation in a minimally invasive bipolar construct.

STUDY DESIGN: Biomechanical human cadaver study. OBJECTIVE: To determine the three-dimensional intervertebral ranges of motion (ROMs) of intact and hook-instrumented thoracic spine specimens subjected to physiological loads, using an in vitro experimental protocol with EOS biplane radiography. Pedicle screws are commonly used in thoracic instrumentation constructs, and their biomechanical properties have been widely studied. Promising clinical results have been reported using a T1-T5 thoracic hook-claw construct for proximal rod anchoring. Instrumentation stability is a crucial factor in minimizing mechanical complications rates but had not been assessed for this construct in a biomechanical study. METHODS: Six fresh-frozen human cadaver C6-T7 thoracic spines were studied. The first thoracic vertebrae were instrumented using two claws of supra-laminar and pedicle hooks, each fixed on two adjacent vertebrae, on either side of a single free vertebra. Quasi-static pure-moment loads up to 5 Nm were applied to each specimen before and after instrumentation, in flexion-extension, right and left bending, and axial rotation. Five steel beads impacted in each vertebra allowed 3D tracking of vertebral movements on EOS biplanar radiographs acquired after each loading step. The relative ranges of motion (ROMs) of each pair of vertebras were computed. RESULTS: Mean ROMs with the intact specimens were 17° in flexion-extension, 27.9° in lateral bending, and 29.5° in axial rotation. Corresponding values with the instrumented specimens were 0.9°, 2.6°, and 7.3°, respectively. Instrumentation significantly (P < 0.05) decreased flexion-extension (by 92-98%), lateral bending (by 87-96%), and axial rotation (by 68-84%). CONCLUSION: This study establishes the biomechanical stability of a double claw-hook construct in the upper thoracic spine, which may well explain the low mechanical complication rate in previous clinical studies. LEVEL OF EVIDENCE: Not applicable, experimental cadaver study.

The spontaneous restoration of the course of psoas muscles after corrective surgery for adult spinal deformity.

BACKGROUND: A previous study demonstrated that spinopelvic alignment and morphology influence a deviation in the course of psoas muscle (PM). However, it is unknown whether such deviations might be caused by a decrease in lumbar lordosis (LL) or the lateral deviation of the lumbar spine following scoliosis. The purpose of this study was to elucidate the close relationship between the coronal and sagittal lumbar alignment and a deviation in the course of PM. METHODS: We investigated the preoperative and postoperative spinopelvic parameters and the morphology of PM at L4/5 level in 30 patients treated with corrective surgery for adult spinal deformity who were diagnosed with "rising psoas sign" before surgery. Spinopelvic parameters were measured on X-ray films. Investigation of the morphology of PM and the morphological measurements were performed using computed tomography (CT) images. The "rising psoas sign" was classified as bilateral- or unilateral-type as defined in the previous study. RESULTS: Among 18 patients who had bilateral-type rising psoas sign before surgery, 11 patients remained bilateral-type after surgery despite an increase in LL. The pelvic incidence of these 11 patients was significantly larger than that of the other 7 patients (53.5 ± 10.2° vs 43.2 ± 5.8°) (p = 0.037). The magnitude of postoperative increase in LL positively correlated with that of the posterior shift of PM (r = 0.41, p = 0.025). The degree of restoration of the lumbar spine following scoliosis was positively correlated with that of the medial shift of PM (r = 0.66, p = 0.025). CONCLUSION: The decrease in LL and the lateral deviation of lumbar spine following scoliosis caused a deviated course of the PM, which was spontaneously corrected by the restoration of lumbar alignment. However, the bilateral-type deviation in patients with higher pelvic incidence was considered to be within the range of normal variation.

Spontaneous regression of calcified thoracic herniations: Can Hounsfield-units radiodensity have a predictive value?

INTRODUCTION: Spontaneous regressions of calcified thoracic disc herniations (TDH) have been rarely described. Since now, no previous papers hypothesized that radiological factors could be able to predict the evolution of the herniation. This study shows that the radiodensity of the herniated material in herniations with spontaneous resolution might differ from that of operated herniations. METHODS: This is a retrospective study. A cohort of patients that underwent surgical removal of a calcified thoracic disc herniation has been compared to two cases conservatively treated and a case with spontaneous regression. CT scans were evaluated to compute the average radiodensity [in Hounsfield units (HU)] of the calcified components of the herniations. All the slices of the CT scans involving the calcification were evaluated in their axial images and in their coronal and sagittal reformations. Comparison of the slices radiodensity (spontaneously resolved versus surgically treated) was performed with the unpaired Student's t test. RESULTS: The mean density of calcification in the case with spontaneous regression was found to be 454 HU. In the control group of surgical cases observed, and the conservatively treated cases, the mean HU density showed higher values (respectively, 827 and 853 HU) (p < 0.01). CONCLUSION: Qualitative differences between calcified TDH that resolve spontaneously or need surgical treatment might be shown by differences of radiodensity. This comparative study, in spite of the limitations due to small numbers, provides a new insight in the interpretation of the phenomenon of spontaneous resolution of calcified TDH. These slides can be retrieved under Electronic Supplementary Material.

Vertebral Compression Fractures Treated in Acute by Instrumented Kyphoplasty: Early and Mid-Term Clinical and Radiological Results.

The treatment of traumatic low-degree vertebral compression fracture remains in a wide range between functional treatment, bracing, vertebroplasty, kyphoplasty, and even surgical fixation. The objective was to assess the innovation of instrumented kyphoplasty and to report the early and mid-term functional and radiological results. This study is a retrospective review of patients enrolled from 2012 to 2017. 104 consecutive endovertebral implantations of instrumented kyphoplasty were reviewed for the study. There were 56 women and 48 men. 93 of 104 patients were evaluated, of whom 27 were evaluated only by retrospective medical record review and 66 with follow-up visit. Clinical parameters were the pain rating scale (VAS) and the Oswestry score questionnaire. The radiological parameters were the vertebral kyphosis, vertebral height, lumbar lordosis, and adjacent disc degeneration (UCLA scale). Statistical correlations between before/after surgery/last follow-up were performed. The average follow-up was 26.7 months (3 to 55). The average VAS decreased from 8.2 to 3.2 the day after surgery, allowing immediate standup. The average Oswestry score was 14.6 at follow-up. The average vertebral kyphosis decreased from 12.9° to 6.5° post-op and stabilized at 8.0° at the last follow-up, corresponding to 28% gain on vertebral height. The lumbar lordosis was restored (+6.6°). Adjacent disc degeneration increased by 1 UCLA grade in 17 patients (16.3%) at follow-up. The instrumented kyphoplasty in acute led to immediate and lasting pain relief, with no bracing or bed rest, short stay in hospital, and quick return to daily life including professional activities. The good clinical results were associated to a stable radiological restoration of the vertebral anatomy.

Effect of cervical flexion and extension on thoracic sagittal alignment.

INTRODUCTION: The cervical spine has the largest sagittal motion in the whole spine, and cervical alignment affects the thoracic sagittal alignment. However, the effects of cervical flexion and extension on thoracic sagittal alignment have not been investigated in detail. The purpose of this study was to analyze the change of thoracic sagittal alignment following cervical flexion and extension. SUBJECTS AND METHODS: A total of 55 consecutive patients (42 men and 13 women; average age 49.1 years) who presented to our department with spinal degenerative disease between January 2016 and September 2017 were enrolled in our study. Subjects with a history of trauma, infection, tumor, inflammatory disease, ossification, or cervical deformities, and those who had undergone spinal surgery were excluded. The following parameters were analyzed: occipito-axial angle (O-C2), C2 slope (C2S), C2-C7 angle, T1 slope (T1S), thoracic kyphosis, T1-T4 angle, T5-T8 angle, T9-T12 angle, lumbar lordosis, sacral slope, pelvic tilt in cervical flexion, neutral, and extension. RESULTS: Cervical flexion significantly decreased O-C2, C2-C7 angles and T1S, and increased C2S. Cervical extension conversely changed these parameters. At cervical flexion, the correlation of C2-C7 angle with thoracic parameters was maintained, except for the T1-T4 angle. At cervical extension, the correlation was observed with T1S and T1-T4 angle. CONCLUSION: Cervical flexion affects the T1S and T5-T8 angle, but there is no significant change in T1-T4 and T9 and lower spino-pelvic columns. This study suggests that T2-T4 can be considered as a stable distal end when cervical long fixation for corrective surgery is performed.