Search

Study Design: A retrospective cohort study using prospectively collected data., Objective: This study primarily aimed to investigate the risk factors for surgery-related complications in primary thoracic spine surgery for degenerative diseases using a surgeon-maintained database. The secondary purpose was to elucidate the characteristics of surgically treated thoracic myelopathy that also required cervical and/or lumbar spine surgery in the study period., Summary of Background Data: Few studies reported surgical complications and the feature of tandem spinal stenosis in thoracic myelopathy in detail because of their rarity., Materials and Methods: This study included 840 thoracic myelopathy patients undergoing primary surgery for degenerative diseases from 2012 to 2021, investigating the effects of diseases, surgical procedures, and patient demographics on postoperative neurological deterioration, dural tear, dural leakage, surgical-site infection, and postoperative hematoma. In thoracic myelopathy patients who were surgically treated and also undergoing cervical and/or lumbar surgery, we investigated the proportion, the effects of diseases, and the order and intervals between surgeries., Results: Multivariate logistic regression revealed that significant risk factors ( P <0.05) for postoperative neurological deterioration were intervertebral disk herniation [odds ratio (OR): 4.59, 95% confidence interval (CI): 1.32-16.0) and degenerative spondylolisthesis (OR: 11.1, 95% CI: 2.15-57.5). Ossification of the ligamentum flavum (OR: 4.12, 95% CI: 1.92-8.86), anterior spinal fusion (OR: 41.2, 95% CI: 4.70-361), and circumferential decompression via a posterior approach (OR: 30.5, 95% CI: 2.27-410) were risk factors for dural tear. In thoracic myelopathy patients surgically treated, 37.0% also underwent degenerative cervical and/or lumbar surgery., Conclusions: Pathologies involving anterior decompression and instability increased the risk of postoperative neurological deterioration. The risk of dural tear was increased when dura mater adhesions were likely to be directly operated upon. It should be recognized that a relatively high proportion (37.0%) of surgically treated thoracic myelopathy patients also underwent cervical and/or lumbar surgery., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Backgrounds: Disadvantages of polyetheretherketone (PEEK) cages are their smooth and hydrophobic surfaces and their lack of osteoconductivity. Titanium (Ti) coated PEEK cage has been innovated to overcome these potential concerns. However, few well-designed studies have investigated the efficacy of Ti-coated PEEK cage on interbody fusion in humans. This study aimed to evaluate the efficacy of Ti coating on bone ongrowth at bone-implant surface by simultaneously comparing Ti-coated and uncoated PEEK cages in the same intervertebral space., Methods: This study is a prospective comparative study for the two different cages. Twenty-six subjects who underwent one-level instrumented posterior lumbar interbody fusion (PLIF) were included. Two PEEK cages [a plasma-sprayed Ti-coated (PTC-PEEK) and an uncoated PEEK cage] were inserted in the same intervertebral space. Fusion rates, cage subsidence, and vertebral cancellous condensation (VCC) around the cage, which indicates bone growth on the surface of each cage, were assessed by thin-slice computed tomography (CT) immediately (within 1 week) and at 3 months postoperatively. A functional radiograph was obtained at 3 and 12 months postoperatively., Results: Twenty-three subjects showed solid fusion at 3 months postoperatively (fusion rate, 88%). Cage subsidence was not observed. VCC was often observed around the PTC-PEEK cage as evaluated by completely synchronized CT images between immediately and at 3 months postoperatively. Quantified VCC around the cage was significantly larger in the PTC-PEEK cage than in the uncoated PEEK cage (P = 0.01)., Conclusions: The Ti-coated PEEK cage exhibits radiographic signs, suggesting bone ongrowth, as represented by VCC around the cage compared with that around the uncoated PEEK cage. The Ti-coated PEEK cage has the potential to promote solid fusion and to improve clinical outcomes in lumbar interbody fusion surgery., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: A consensus on the optimal surgical procedure for thoracolumbar OVF has yet to be reached due to the previous relatively small number of case series. The study was conducted to investigate surgical outcomes for osteoporotic vertebral fracture (OVF) in the thoracolumbar spine., Methods: In total, 315 OVF patients (mean age, 74 years; 68 men and 247 women) with neurological symptoms who underwent spinal fusion with a minimum 2-year follow-up were included. The patients were divided into 5 groups by procedure: anterior spinal fusion alone (ASF group, n = 19), anterior/posterior combined fusion (APSF group, n = 27), posterior spinal fusion alone (PSF group, n = 40), PSF with 3-column osteotomy (3CO group, n = 92), and PSF with vertebroplasty (VP + PSF group, n = 137)., Results: Mean operation time was longer in the APSF group (p < 0.05), and intraoperative blood loss was lower in the VP + PSF group (p < 0.05). The amount of local kyphosis correction was greater in the APSF and 3CO groups (p < 0.05). Clinical outcomes were approximately equivalent among all groups., Conclusion: All 5 procedures resulted in acceptable neurological outcomes and functional improvement in walking ability. Moreover, they were similar with regard to complication rates, prevalence of mechanical failure related to the instrumentation, and subsequent vertebral fracture. Individual surgical techniques can be adapted to suit patient condition or severity of OVF., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Aims: The aim of this study was to explore risk factors for complications associated with dural tear (DT), including the types of DT, and the intra- and postoperative management of DT., Patients and Methods: Between 2012 and 2017, 12 171 patients with degenerative lumbar diseases underwent primary lumbar spine surgery. We investigated five categories of potential predictors: patient factors (sex, age, body mass index, and primary disease), surgical factors (surgical procedures, operative time, and estimated blood loss), types of DT (inaccessible for suturing/clipping and the presence of cauda equina/nerve root herniation), repair techniques (suturing, clipping, fibrin glue, polyethylene glycol (PEG) hydrogel, and polyglycolic acid sheet), and postoperative management (drainage duration). Postoperative complications were evaluated in terms of dural leak, prolonged bed rest, headache, nausea/vomiting, delayed wound healing, postoperative neurological deficit, surgical site infection (SSI), and reoperation for DT. We performed multivariable regression analyses to evaluate the predictors of postoperative complications associated with DT., Results: In total, 429/12 171 patients (3.5%) had a DT. Multivariable analysis revealed that PEG hydrogel significantly reduced the incidence of dural leak and prolonged bed rest, and that patients treated with sealants (fibrin glue and PEG hydrogel) significantly less frequently suffered from headache. A longer drainage duration significantly increased the incidence of headache, nausea/vomiting, and delayed wound healing. Headache and nausea/vomiting were significantly more prevalent in younger female patients. Postoperative neurological deficit and reoperation for DT significantly depended on the presence of cauda equina/nerve root herniation. A longer operative time was the sole independent risk factor for SSI and was also a risk factor for dural leak, prolonged bed rest, and nausea/vomiting., Conclusion: Sealants, particularly PEG hydrogel, may be useful in reducing symptoms related to cerebrospinal fluid leakage, whereas prolonged drainage may be unnecessary. Younger female patients should be carefully treated when DT occurs. Cite this article: Bone Joint J 2019;101-B:1115-1121.

Case: A 76-year-old woman underwent L4-L5 posterior lumbar interbody fusion with pedicle screws for lumbar spondylolisthesis. Intraoperative iatrogenic injuries to the right fourth lumbar artery and inferior vena cava occurred, resulting in arteriovenous fistula with extensive retroperitoneal hemorrhage. Endovascular treatment and intraperitoneal drainage were effective in managing retroperitoneal hemorrhage. She showed no sign of organ failure or deep venous thrombosis during her 2-year follow-up., Conclusions: We recommend embolization both proximally and distally in the case of lumbar artery injury. Intra-abdominal hypertension secondary to a massive retroperitoneal hematoma should also be considered to prevent abdominal compartment syndrome.

Background: Lumbosacral orthoses (LSOs) are used as standard care after lumbar fusion surgery though their efficacy is unknown. The purpose of this prospective randomized controlled study was to elucidate the clinical and radiographic efficacies of LSO treatment in patients who underwent posterior lumbar interbody fusion (PLIF) of less than 3 segments., Methods: Seventy-three patients who underwent PLIF were randomly allocated to 3 groups: 1 with custom-made LSO with metallic stays (C group); 1 with ready-made LSO without metallic stays (R group), and 1 without LSO (N group). The patients in the C and R groups were instructed to wear LSO postoperatively for 3 months. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) score, JOA-back pain evaluation questionnaire (JOABPEQ), Roland-Morris Disability Questionnaire, and 100-mm visual analog scale for low back pain. Radiographic evaluation included intervertebral fusion rates and loss of correction postoperatively at 2 years., Results: A significant difference in the clinical outcomes was observed only for the lumbar dysfunction domain of JOABPEQ postoperatively at 1 month (N vs C groups; 45% vs 10%, P = .03). Radiographic outcomes were not different between the groups., Conclusions: No effect of orthosis treatment for less than 3 segments in PLIF was observed on clinical and radiographic outcomes. The type of orthosis also did not influence the outcomes. These results suggest that the use of LSO for PLIF can be simplified or is omissible except in patients with severe osteoporosis.

Background: To date, there have been little published data on surgical outcomes for patients with PD with thoracolumbar OVF. We conducted a retrospective multicenter study of registry data to investigate the outcomes of fusion surgery for patients with Parkinson's disease (PD) with osteoporotic vertebral fracture (OVF) in the thoracolumbar junction., Methods: Retrospectively registered data were collected from 27 universities and their affiliated hospitals in Japan. In total, 26 patients with PD (mean age, 76 years; 3 men and 23 women) with thoracolumbar OVF who underwent spinal fusion with a minimum of 2 years of follow-up were included (PD group). Surgical invasion, perioperative complications, radiographic sagittal alignment, mechanical failure (MF) related to instrumentation, and clinical outcomes were evaluated. A control group of 296 non-PD patients (non-PD group) matched for age, sex, distribution of surgical procedures, number of fused segments, and follow-up period were used for comparison., Results: The PD group showed higher rates of perioperative complications (p < 0.01) and frequency of delirium than the non-PD group (p < 0.01). There were no significant differences in the degree of kyphosis correction, frequency of MF, visual analog scale of the symptoms, and improvement according to the Japanese Orthopaedic Association scoring system between the two groups. However, the PD group showed a higher proportion of non-ambulators and dependent ambulators with walkers at the final follow-up (p < 0.01)., Conclusions: A similar surgical strategy can be applicable to patients with PD with OVF in the thoracolumbar junction. However, physicians should pay extra attention to intensive perioperative care to prevent various adverse events and implement a rehabilitation regimen to regain walking ability.

Background: Cortical pedicle screw placement is an attractive technique in terms of both fixation strength and less invasiveness. However, to insert the screw with penetrating cortical bone on the ideal trajectory is technically demanding. The use of three-dimensional (3D) patient-matched guides may facilitate the use of this technique., Purpose: To examine the accuracy of cortical screw placement using a patient-matched targeting guide with a cadaveric study assessing the accuracy., Methods: The 3D planning of the pedicle screw placement, including the location at which the screw would pass through the center of the pedicle, sagittal/transverse trajectory (angle), length, and diameter, was developed using 3D CAD design software. Three-dimensional guides based on the preoperative planning were created for three cadaveric specimens (L1 to S1, 36 pedicles). Screws (n = 18) and pins (n = 18) were placed using K-wire or drill-based guides, without X-ray exposure. Actual positioning was compared to the preoperative plan by superimposing the inserted screws/pins based on postoperative CT. The placement accuracy was graded based on the degree of perforation of the pedicle by the pedicle screw or pin using an acceptance criterion (no perforation; Grade A, 0-2 mm; Grade B, 2-4 mm; and Grade C, >4 mm). The mean deviation between the planned and inserted screw positions on the coronal plane at the midpoint of the pedicle was compared to the accuracy of screw guide for traditional pedicle screw trajectory (0.70 mm)., Results: Of 35 evaluated screws and pins, 32 (91.4%) were inserted completely inside the pedicle. All pedicle perforation was within 2 mm. The mean deviation from the plan at the midpoint of pedicle was 0.66 mm; thus, the accuracy was within the predefined criteria., Conclusions: Cortical pedicle screw placement using 3D-patient matched guides is accurate. Further clinical studies are required to confirm the radiographic and clinical effects., (Copyright © 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Object: This study aims to clarify the clinical potential of Hounsfield unit (HU), measured on computed tomography (CT) images, as a predictor of pedicle screw (PS) loosening, compared to bone mineral density (BMD)., Methods: A total of 206 screws in 52 patients (21 men and 31 women; mean age 68.2 years) were analyzed retrospectively. The screws were classified into two groups depending on their screw loosening status on 3-month follow-up CT (loosening screw group vs. non-loosening screw group). Preoperative HU of the trajectory was evaluated by superimposing preoperative and postoperative CT images using three-dimensional image analysis software. Age, sex, body mass index, screw size, BMD of lumbar, and HU of screw trajectory were analyzed in association with screw loosening. Multivariate logistic regression analysis was performed, and the thresholds for PS loosening risk factors were evaluated using a continuous numerical variable and receiver operating characteristic (ROC) curve analyses. The area under the curve (AUC) was used to determine the diagnostic performance, and values > 0.75 were considered to represent good performance., Results: The loosening screw group contained 24 screws (12%). Multivariate analysis revealed that the significant independent risk factors were not BMD but male sex [P = 0.028; odds ratio (OR) 2.852, 95% confidence interval (CI) 1.120-7.258] and HU of screw trajectory (P = 0.006; OR 0.989, 95% CI 0.980-0.997). ROC curve analysis demonstrated that the AUC for HU of screw trajectory for women was 0.880 (95% CI 0.798-0.961). The cutoff value was 153.5. AUC for men was 0.635 (95% CI 0.449-0.821), which was not considered to be a good performance., Conclusions: Low HU of screw trajectories was identified as a risk factor of PS loosening for women. For female patients with low HU, additional augmentation is recommended to prevent PS loosening., (Copyright © 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Bone ongrowth on the surfaces of titanium (Ti)-coated polyetheretherketone (PEEK) materials has been demonstrated in animal models; however, whether this occurs on the surfaces of Ti-coated PEEK cages in lumbar interbody fusion has not been demonstrated clinically in vivo. This prospective observational study was aimed to develop and validate a computed tomography (CT) color mapping based on Hounsfield unit (HU) values for evaluation of bone ongrowth on the surfaces of the Ti-coated PEEK cage after posterior lumbar interbody fusion (PLIF).Twenty-four consecutive patients (11 men and 13 women; mean age, 67.0 years; range, 20-82 years) who underwent single- or 2-level PLIF since March 2015 were included. Two Ti-coated PEEK cages were inserted in all PLIF segments. From reconstructed sagittal planes from postoperative CT scans (within 1 week and 6 months postoperatively), bone ongrowth on the surfaces of cage frames was evaluated by CT color mapping. Inter- and intraobserver reliability of the assessment of bone ongrowth by CT color mapping was evaluated by Cohen's kappa coefficient. The relation between CT color mapping and HU values on the surfaces of cage frames was also analyzed.A total of 248 surfaces of cage frames were evaluated. Bone ongrowth was observed in 134 of 248 surfaces (54.0%) by CT color mapping. Intraobserver reliability for the evaluation of bone ongrowth was kappa = 0.831, and interobserver reliability was kappa = 0.713. The HU values in the local regions of interest (ROIs) on the surfaces of cage frames where the postoperative bone ongrowth existed on CT color mapping increased significantly postoperatively (P < .001), and the median postoperative change rate of the HU values in the local ROIs was 22.4%.The assessment of bone ongrowth on the surfaces of Ti-coated PEEK cages by CT color mapping had adequate inter- and intraobserver reliability, which was useful especially in detecting local increase in HU values on the surfaces of the cages. This method is an easy and visually comprehensible method for the assessment of bone ongrowth in the bone-implant interface.

Study Design: A retrospective review of prospectively collected data., Objective: To investigate the incidence of radiographic and symptomatic adjacent segment disease (ASD) and identify possible risk factors for ASD after posterior lumbar interbody fusion (PLIF) with minimum disc distraction by selecting low-height interbody cages., Summary of Background Data: Excessive disc space distraction is reportedly 1 of the risk factors for ASD after PLIF; however, the incidence and other risk factors of ASD after PLIF with minimum disc distraction remain unclear., Methods: Forty-one consecutive patients who underwent PLIF at L4-L5 and were postoperatively followed up for a minimum of 2 years were included. The height and shape (box or bullet shape) of interbody cages was determined according to the disc height and morphology of the intervertebral space assessed on preoperative computed tomography scans to avoid excessive distraction. The incidence of radiographic and symptomatic ASD was evaluated and all demographic and radiographic parameters were compared between patients with and without ASD. Multivariate logistic regression analysis was performed to identify risk factors for ASD among the variables with P < .20 in univariate analysis., Results: The overall incidence of ASD was 12.2% (5/41 patients): radiographic ASD, 7.3% (3 patients); symptomatic ASD, 4.9% (2 patients). Multivariate analysis revealed preoperative retrolisthesis of L3 on extension as the sole risk factor for ASD after PLIF with minimum disc distraction (odds ratio, 2.13; 95% confidence interval, 1.00-4.05; P = .049)., Conclusions: The incidence of ASD in this study was lower than that of ASD in our previous study about PLIF with distraction of disc space (12.2% vs. 31.8%). Minimum disc distraction by selection of low-height interbody cages is a simple and effective method to prevent ASD at the surgeons' discretion, although preexisting retrolisthesis at the adjacent upper segment should be taken into consideration., (Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Background: Recent morphological analyses of vertebrae in patients with scoliosis have revealed three-dimensional (3D) deformities in the vertebral bodies. However, it remains controversial whether these deformities are secondary changes caused by asymmetrical vertebral loading or primary changes caused by aberrant asymmetrical vertebral growth. Furthermore, the difference in vertebral morphology between scoliosis with different pathogeneses remains unclear. This study was aimed to investigate the difference in the coronal asymmetry of vertebral bodies between neuromuscular scoliosis (NS) in Duchenne muscular dystrophy (DMD) and idiopathic scoliosis (IS) using in vivo 3D analysis., Methods: Twelve male skeletally immature patients with NS in DMD and 13 female skeletally immature patients with IS who underwent corrective fusion at our institution were included retrospectively. 3D bone models of the apical and adjacent upper and lower vertebrae in the major curve in the NS patients and in the main and compensatory curves in the IS patients were constructed using an image processing workstation. The heights of the concave and convex sides of the vertebral bodies were measured at the anterior, middle, and posterior and the concave-to-convex vertebral height ratios (VHR) were calculated., Results: The mean VHRs (anterior/middle/posterior) for the main curve for IS (0.897 ± 0.072/0.832 ± 0.086/0.883 ± 0.059) were significantly smaller than those for NS (0.970 ± 0.048/0.934 ± 0.081/0.958 ± 0.043) in all three parts (p < 0.001). Those of the compensatory curve in IS (0.968 ± 0.045/0.942 ± 0.067/0.967 ± 0.046) did not differ significantly from the NS values in any part., Conclusions: When compared to the wedging of the vertebral bodies around apical vertebrae in the major curve in NS, which was caused by asymmetric loading, the wedge deformities in both the main and compensatory curves in IS were more severe than would be expected. Our results indicated that morphometric characteristics of vertebral bodies differed according to the pathogenesis of scoliosis and that the pathology of the wedging of vertebral bodies in IS could not be a result only of asymmetric loading to the vertebral bodies.

Study Design: A retrospective review of prospectively collected data., Objective: The present study aimed to identify risk factors for poor patient-reported quality of life (QOL) outcomes, based on five categories (pain-related disorders, lumbar spine dysfunction, gait disturbance, social life dysfunction, and psychological disorders) of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), after posterior lumbar interbody fusion (PLIF) at the 2-year follow-up., Summary of Background Data: Many studies have been reported on patient QOL outcomes after lumbar surgery; however, few reports have focused on risk factors for poor postoperative QOL outcomes in terms of the various disabilities and dysfunctions after PLIF., Methods: One hundred consecutive patients (39 men and 61 women; mean age 69.6 [44-84] yr) who underwent single- or two-level PLIF for degenerative spondylolisthesis and/or foraminal stenosis with a 2-year follow-up were included. The effectiveness of surgery in each category of the JOABPEQ was evaluated. Demographic and clinical data and radiographic parameters were reviewed. Risk factors for poor postoperative QOL outcomes in each category of the JOABPEQ were investigated by multivariate logistic regression analysis., Results: Older age and spinopelvic malalignment (preoperative high pelvic tilt or postoperative decrease in lumbar lordosis [=postoperative increase in the mismatch between pelvic incidence and lumbar lordosis]) were risk factors for poor postoperative QOL outcomes in all categories of the JOABPEQ, except for lumbar spine dysfunction. In contrast, increase in number of PLIF segments, non-union, and radiographic adjacent segment degeneration were risk factors for poor postoperative QOL outcomes in lumbar spine dysfunction and gait disturbance., Conclusion: The risk factors for poor QOL outcomes after PLIF differed among the five categories of the JOABPEQ. In particular, surgery-related factors (e.g., increase in number of PLIF segments, nonunion, and radiographic adjacent segment degeneration) had a negative effect on the improvement of lumbar spine dysfunction and gait disturbance., Level of Evidence: 4.

Background: Vertebral bodies in patients with adolescent idiopathic scoliosis (AIS) usually have frontal wedge deformities. However, the plasticity of the deformed vertebrae in skeletally immature patients is unknown. The purpose of our study was to clarify the plasticity of vertebral deformities in skeletally immature patients with AIS by using in vivo three-dimensional (3D) analysis., Methods: Ten female patients with AIS (mean age, 12.2 years; three patients, Lenke type 1; five patients, type 2; two patients, type 5) who underwent posterior fusion and whose Risser grade was ≤3 at surgery were included. Using computed tomography images (0.625-mm slice thickness) obtained 1 week and 1 year postoperatively, a total of seventy-three 3D bone models of vertebrae was made. The 3D bone models were made between the upper and lower end vertebrae within the main thoracic curve for patients with Lenke types 1 and 2 scoliosis, whereas they were made within the thoracolumbar/lumbar curve in patients with Lenke type 5 scoliosis. The height of the concave and convex sides in the anterior, middle and posterior parts of the vertebral bodies was measured using the original digital viewer, and the vertebral height ratio (VHR: concave/convex) was calculated. VHRs at 1 week and 1 year postoperatively were compared using the Wilcoxson signed-rank test. Differences were considered statistically significant at p < 0.05., Results: VHR of the end vertebrae (n = 20) did not change postoperatively for any parts of the vertebral bodies. VHR of the vertebrae in the apical region (n = 28) also remained unchanged postoperatively. In contrast, VHR of the other vertebrae (n = 25) increased significantly in the anterior part postoperatively (from 0.938 to 0.961, p = 0.006)., Conclusions: The wedge deformity of vertebral bodies showed a reshaping potential towards a symmetrical configuration in the region other than end and apex, although no plasticity of the vertebrae was observed in the apical region even in skeletally immature patients with AIS.

Aims: To clarify the asymmetrical ossification of the epiphyseal ring between the convex and concave sides in patients with adolescent idiopathic scoliosis (AIS)., Patients and Methods: A total of 29 female patients (mean age, 14.4 years; 11 to 18) who underwent corrective surgery for AIS (Lenke type 1 or 2) were included in our study. In all, 349 vertebrae including 68 apical vertebrae and 87 end vertebrae in the main thoracic (MT) curve and thoracolumbar/lumbar (TL/L) curve were analysed. Coronal sections (anterior, middle and posterior) of the vertebral bodies were reconstructed from pre-operative CT scans (320-row detector; slice thickness, 0.5 mm) and the appearances of the ossification centre in the epiphyseal ring at four corners were evaluated in three groups; all vertebrae excluding end vertebrae, apical vertebrae and end vertebrae. The appearance rates of the ossification centre at the concave and convex sides were calculated and compared., Results: The appearance rates of the ossification centres in all vertebrae excluding end vertebrae and apical vertebrae were significantly lower on the concave side than on the convex side in both MT and TL/L curves irrespective of curve flexibility. There was no significant difference in the rate of appearance of the ossification centres on the concave or convex sides in end vertebrae., Conclusion: The asymmetric bony growth of vertebral body came into existence at both structural and non-structural curves, and was more apparent around the apical vertebrae. Evaluation of the ossification centre in the epiphyseal ring could be a measure of the effectiveness of brace treatment., Take Home Message: The ossification of the epiphyseal ring in patients with AIS was delayed or absent on the concave side particularly around the apical vertebrae. Cite this article: Bone Joint J 2016;98-B:666-71., (©2016 The British Editorial Society of Bone & Joint Surgery.)

Background Context: Bone morphogenetic proteins (BMPs) are a group of dimeric growth factors that belong to the transforming growth factor super family and are capable of eliciting new bone formation. Previous studies have suggested that the coexpression of two different BMP genes in a cell can result in the production of BMP heterodimers that are more potent than homodimers. However, because of the difficulty in optimizing the level of BMP gene expression, the coexpression of two different BMP genes also produces BMP homodimers as a by-product. These homodimers could, in theory, interact with the heterodimers., Purpose: To elucidate the effects of a BMP-2/7 heterodimer, which were investigated in depth using purified BMP-2/7 heterodimers, BMP-2 homodimers, and BMP-7 homodimers in a rat spinal fusion model., Methods: Bilateral posterolateral fusion at L4-L5 was performed in four different groups: control group animals were implanted with collagen carriers alone; BMP-7 group animals with collagen carriers+1 μg of BMP-7 homodimer; BMP-2 group animals with collagen carriers+1 μg of BMP-2 homodimer; and BMP-2/7 group animals with collagen carriers+1 μg of the BMP-2/7 heterodimer. The following assessments were performed: bone microstructural analysis of the fusion mass and tissue volume (TV) with microcomputed tomography (micro-CT); fusion assessment with manual palpation testing and three-dimensional CT images; and bone histomorphometrical analysis of the fusion mass., Results: The fusion scores, as determined by radiography, and the TV of the newly formed bone, as determined by micro-CT, were significantly higher in the BMP-2/7 heterodimer group than the other groups (p<.0001). The microstructural indices of the newly formed bone did not differ between the groups. Moreover, histologic analysis of the fused spines revealed that the formation of the trabecular bone bridging the transverse process was the highest in this group., Conclusions: This study demonstrated that BMP-2/7 heterodimer is a stronger inducer of bone regeneration than BMP-2 or -7 homodimers. The use of a purified BMP-2/7 heterodimer may represent an efficient alternative to the current clinical use of BMP-2 or -7 homodimers. Further studies as to the side effects of BMP-2/7 heterodimer are required., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background Context: There has been no study regarding the effect of intermittent administration of teriparatide (TPTD [recombinant human parathyroid hormone (1-34)]) on spinal fusion in patients with glucocorticoid-induced osteoporosis (GIOP)., Purpose: To elucidate the effect of intermittent administration of TPTD on spinal fusion in rats with GIOP., Study Design: An experimental animal study of rats under continuous glucocorticoid (GC) exposure undergoing spinal fusion surgery and administration of TPTD or saline., Methods: Male 8-week-old rats (n=18) were administered 5 mg/kg methylprednisolone (MP) for 12 weeks. After 6 weeks of MP administration, the rats underwent posterolateral spinal fusion (L4-L5) with iliac crest autograft. Then, five times a week, they were given either saline or 40 μg/kg TPTD for 6 weeks. The following assessments were performed: time-course bone microstructural analysis of the fusion mass and adjacent vertebrae (L6), with in vivo microcomputed tomography (μCT); fusion assessment, with manual palpation testing and three-dimensional CT images; and bone histomorphometrical analysis of the fusion mass., Results: In the TPTD group, values for bone volume and other bone microstructural parameters at the fusion mass increased and peaked 4 weeks after surgery, and these values were significantly greater than those for the control (CNT) group at 4 and 6 weeks after surgery. Fusion assessment showed that fusion rate was higher in the TPTD group than in the CNT group (CNT group: 56%, TPTD group: 89%). Bone histomorphometry revealed that values for bone formation parameters were significantly higher in the TPTD group than in the CNT group., Conclusions: Under continuous GC exposure in a rat model of spinal fusion, intermittent TPTD administration accelerated bone modeling and remodeling predominantly by stimulating bone formation at the fusion mass and increasing the fusion rate. Intermittent TPTD administration also improved bone microarchitecture of adjacent vertebrae., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Although delayed union or pseudoarthrosis after lumbar arthrodesis has been recognized as a major radiographic complication, little has been known about the effect of fusion status on the patient's quality-of-life (QOL) outcome. The purpose of this study was to investigate the effects of fusion status after posterior lumbar interbody fusion (PLIF) on QOL outcomes by using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ)., Methods: Among 100 patients who underwent single level PLIF for spinal canal stenosis, 29 who had not achieved fusion (incomplete fusion group) and 29 age- and sex ratio-matched patients who had achieved fusion (fusion group) 6 months after surgery were enrolled. Overall clinical evaluation was performed before and 6 months after surgery: the physician determined the Japanese Orthopaedic Association Score for Low Back Pain (JOA score); the JOABPEQ and visual analogue scale (VAS) values were collected. The recovery rate of the JOA score, changes in all JOABPEQ subdomain scores and in the VAS values were calculated. All variables were compared between the groups., Results: The preoperative JOA scores, JOABPEQ scores of all subdomains, and VAS values of all categories did not differ between the groups. The recovery rate was higher in the fusion group than the incomplete fusion group (p = 0.0185). The changes in the JOABPEQ scores for walking ability and social life function were significantly greater in the fusion group than the incomplete fusion group (walking ability, p = 0.0172; social life function, p = 0.0191). The postoperative VAS values and changes in the VAS values for all categories did not differ between the groups., Conclusions: Incomplete fusion after PLIF correlated with poor improvement in walking ability and social life function. Therefore, the achievement of fusion after PLIF is essential to obtain better patient QOL outcomes.

Background: Although clinical bone morphogenetic protein (BMP) therapy is effective at enhancing bone formation in patients managed with spinal arthrodesis, the required doses are very high. Teriparatide (parathyroid hormone 1-34) is approved by the U.S. Food and Drug Administration to treat osteoporosis and is a potent anabolic agent. In this study, intermittent administration of parathyroid hormone 1-34 combined with transplantation of BMP was performed to elucidate the effect of parathyroid hormone 1-34 on the fusion rate and quality of newly formed bone in a rat model., Methods: A total of forty-eight male Sprague-Dawley rats underwent posterolateral lumbar spinal arthrodesis with one of three different treatments with recombinant human (rh) BMP-2: (1) 0 μg (control), (2) 2 μg (low dose), or (3) 50 μg (high dose). Each of the rhBMP-2 treatments was studied in combination with intermittent injections of either parathyroid hormone 1-34 (180 μg/kg/wk) or saline solution starting two weeks before the operation and continuing until six weeks after the operation. Osseous fusion was assessed with use of radiographs and a manual palpation test. Microstructural indices of the newly formed bone were evaluated with use of micro-computed tomography. The serum markers of bone metabolism were also quantified., Results: The fusion rate in the group treated with 2 μg of rhBMP-2 significantly increased (from 57% to 100%) with the administration of parathyroid hormone 1-34 (p < 0.05). The fusion rates in the other groups did not change significantly with the administration of parathyroid hormone 1-34. The bone volume density of the newly formed bone significantly increased in both the 2-μg and 50-μg rhBMP-2 treatment groups with the administration of parathyroid hormone 1-34 (p < 0.01). Micro-computed tomography scans of the newly formed bone clearly demonstrated an abundance of trabecular bone formation in the group treated with parathyroid hormone 1-34. In addition, serum levels of osteocalcin were significantly increased in the parathyroid hormone 1-34 treatment group., Conclusions: Intermittent administration of parathyroid hormone 1-34 significantly increased fusion rates in the group treated with low-dose rhBMP-2, and it improved the quality of the newly formed bone in both the high and low-dose groups in a rat model of rhBMP-2-induced spinal fusion., Clinical Relevance: Our results suggest that the combined administration of rhBMP-2 and parathyroid hormone 1-34 may lead to efficient bone regeneration., (Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.)

Study Design: A retrospective cross-sectional study., Objective: The aim of this study was to identify the prevalence of and risk factors for lumbar scoliosis in patients with rheumatoid arthritis (RA) using lumbar images obtained from dual-energy x-ray absorptiometry (DXA)., Summary of Background Data: The prevalence of lumbar scoliosis in the normal adult population has been reported, but that in patients with RA remains unclear., Methods: Subjects comprised 241 patients with RA who underwent annual DXA. Cobb angles of the lumbar spine were measured by lumbar anteroposterior DXA and the prevalence of lumbar scoliosis (curvature ≥10°) was calculated. Correlations between lumbar scoliosis and potential risk factors (age, sex, duration of RA, T score of lumbar spine and hip, medications for RA [daily predonisolone dose, use of biological agents] and osteoporosis, disease activity score-C-reactive protein, progression stage and functional classification of RA, and severity of hand deformity were analyzed., Results: The prevalence of lumbar scoliosis in patients with RA was 32.0%. Mean Cobb angle was 7.1º ± 5.5º among all subjects, compared with 13.6º ± 4.4º (range, 10º-32º) among subjects with scoliosis. Subjects with scoliosis were significantly older (67.8 yr) than those without (61.6 yr, P < 0.0001). The daily prednisolone dose was significantly higher in subjects with scoliosis (4.14 mg) than in those without (3.46 mg, P = 0.0389). The T score of the hip was significantly smaller in subjects with scoliosis (-1.79) than in those without (-1.26, P = 0.0005). A multivariate logistic regression analysis revealed age as the sole risk factor for lumbar scoliotic changes in patients with RA (odds ratio, 1.068; 95% confidence interval, 1.031-1.107; P = 0.0003)., Conclusion: The prevalence of lumbar scoliosis in patients with RA was 32.0%, about 3- or 4-times higher than its prevalence as obtained from previous reports of DXA cohorts irrespective of RA. Increased age represented an independent risk factor for lumbar scoliosis in patients with RA., Level of Evidence: 4.

Object: Although the anatomy of the thoracic pedicle in adolescent idiopathic scoliosis is well known, that of the lumbar pedicle in degenerative lumbar scoliosis is not. The morphometric differences between the pedicles on the concave and convex sides can result in an increased risk of malpositioned pedicle screws. The purpose of this study was to analyze the lumbar pedicle morphology in degenerative lumbar scoliosis using multiplanar reconstructed CT., Methods: The study group comprised 16 consecutive patients (1 man and 15 women, mean age 70.9 ± 4.5 years) with degenerative lumbar scoliosis characterized by a Cobb angle of at least 30° who underwent preoperative helical CT scans. The CT data in DICOM format were reconstructed, and the following parameters were measured for each pedicle inside the curves: the inner cortical transverse pedicle width (TPWi) and outer cortical transverse pedicle width (TPWo) and axial angle, all on an axial plane, and the inner cortical minimum pedicle diameter (MPDi) and outer cortical minimum pedicle diameter (MPDo) and cephalocaudal inclination of the pedicle, all on the plane perpendicular to the pedicle axis. The cortical thickness and cortical ratio of the pedicles on the axial plane and the plane perpendicular to the pedicle axis were calculated. Data were obtained for a total of 124 pedicles; L-1, 26 pedicles in 13 patients; L-2, 32 pedicles in 16 patients; L-3, 32 pedicles in 16 patients; L-4, 28 pedicles in 14 patients; and L-5, 6 pedicles in 3 patients., Results: Among the target vertebrae, the TPWi, MPDi, and MPDo were significantly smaller and the axial angle was significantly larger on the concave side than on the convex side (TPWi, 6.37 vs 6.70 mm, p < 0.01; MPDi, 5.15 vs 5.67 mm, p < 0.01; MPDo, 7.91 vs 8.37 mm, p < 0.05; axial angle, 11.79° vs 10.56°, p < 0.01). The cortical ratio of the pedicles was larger on the concave side than on the convex side (on the axial plane, 0.29 vs 0.26, p < 0.05; on the plane perpendicular to the pedicle axis, 0.36 vs 0.32, p < 0.01). These differences were most evident at L-4., Conclusions: This study demonstrated lumbar pedicle asymmetry in degenerative lumbar scoliosis. The authors speculate that these asymmetrical changes were attributed to the remodeling caused by axial load imbalance and the limited space available for pedicles on the concave side. On the concave side, because of the narrower pedicle diameter and larger axial angle, surgeons should carefully determine screw size and direction when inserting pedicle screws to prevent possible pedicle wall breakage and neural damage.

Purpose: The measurement of transverse pedicle width is still recommended for selecting a screw diameter despite being weakly correlated with the minimum pedicle diameter, except in the upper lumbar spine. The purpose of this study was to reveal the difference between the minimum pedicle diameter and conventional transverse or sagittal pedicle width in degenerative lumbar spines., Methods: A total of 50 patients with degenerative lumbar disorders without spondylolysis or lumbar scoliosis of >10° who preoperatively underwent helical CT scans were included. The DICOM data of the scans were reconstructed by imaging software, and the transverse pedicle width (TPW), sagittal pedicle width (SPW), minimum pedicle diameter (MPD), and the cephalocaudal inclination of the pedicles were measured., Results: The mean TPW/SPW/MPD values were 5.46/11.89/5.09 mm at L1, 5.76/10.44/5.39 mm at L2, 7.25/10.23/6.52 mm at L3, 9.01/9.36/6.83 mm at L4, and 12.86/8.95/7.36 mm at L5. There were significant differences between the TPW and MPD at L3, L4, and L5 (p < 0.01) and between the SPW and MPD at all levels (p < 0.01)., Conclusions: The MPD was significantly smaller than the TPW and SPW at L3, L4, and L5. The actual measurements of the TPW were not appropriate for use as a direct index for the optimal pedicle screw diameter at these levels. Surgeons should be careful in determining pedicle screw diameter based on plain CT scans especially in the lower lumbar spine.

Object: Spinal fusion at the L4-5 disc space alters the normal biomechanics of the spine, and the loss of motion at the fused level is compensated by increased motion and load at the other unfused segments. This may lead to deterioration of the adjacent segments of the lumbar spine, called adjacent-segment disease (ASD). In this study, the authors investigate the distracted disc height of the fused segment, caused by cage or bone insertion during surgery, as a novel risk factor for ASD after posterior lumbar interbody fusion (PLIF)., Methods: Radiographic L3-4 ASD is defined by development of spondylolisthesis greater than 3 mm, a decrease in disc height of more than 3 mm, or intervertebral angle at flexion smaller than -5 degrees . Symptomatic ASD is defined by a decrease of 4 points or more on the Japanese Orthopaedic Association scale. Eighty-five patients with L-4 spondylolisthesis treated by L4-5 PLIF underwent follow-up for more than 2 years (mean 38.8 +/- 17.1 months). The patients were divided into 3 groups according to the final outcome. Group A comprised those patients without ASD (58), Group B patients had radiographic ASD (14), and Group C patients had symptomatic ASD (13)., Results: The L4-5 disc space distraction by cage insertion was 3.1 mm in the group without ASD, 4.4 mm in the group with radiographic ASD, and 6.2 mm in the group with symptomatic ASD, as measured using lateral spinal radiographs just after surgery. Multivariate analysis showed that distraction was the most significant risk factor., Conclusions: The excessive distraction of the L4-5 disc space during PLIF surgery is a significant and potentially avoidable risk factor for the development of radiographic, symptomatic ASD.

Object: Although posterior lumbar interbody fusion (PLIF) is an excellent procedure to attain circumferential decompression, it is technically demanding and can lead to various surgical complications. The authors retrospectively reviewed consecutive patients with nonisthmic spondylolisthesis who underwent PLIF to reveal the incidence and risk factors for perioperative complications of PLIF., Methods: A total of 240 patients underwent PLIF. The fusion level was at L4-5 in 220, L3-4 in 18, and L5-S1 in 2. The medial walls of the fusion segment's facet joints were resected, and the VSP Spine System was used for the pedicle screw instrumentation. The operations were performed by 7 surgeons, who were divided into 4 groups according to their level of experience with spinal surgery., Results: The average operation time was 175 +/- 49 minutes, and the estimated blood loss was 746 +/- 489 ml. A total of 90 patients (37.5%) experienced complications; 41 (17%) experienced transient neurological complications, and 18 (7.5%) experienced permanent neurological complications. The mean neurological score according to the Japanese Orthopaedic Association improved from 14.3 +/- 3.8 to 24.7 +/- 4.0 in the patients without complications and from 14.8 +/- 3.6 to 24.0 +/- 3.9 in the patients with complications. Multivariate analysis concerning the relationship between complications and risk factors (operation time, estimated intraoperative blood loss, and surgeon experience) revealed that operation time was the only significant risk factor for complications., Conclusions: Perioperative complications of PLIF were more frequent in this homogeneous study group than in other studies of various implants. Total excision of the facet joints might preclude neurological complications.

The authors describe a rare case of a congenital absence of the right L5 pedicle in a 54-year-old man presenting with low back pain and radicular pain of his left leg. Plain x-ray films, computed tomography scan (CT) after myelography, and three-dimensional CT revealed the absence of the L5 pedicle and anomaly of the L4-L5 facet joint on his right side. On the left side, there were severe degenerative changes that were thought to be the result of an overload and instability. The degenerative changes led to late-onset neurologic impairment of the contralateral side, which was treated with spinal fusion. To our knowledge, this is the first report of contralateral symptoms due to unilateral defect of the facet joint accompanied by aplasia of a pedicle.