A comparison of dynamic views using plain radiographs and thin-section three-dimensional computed tomography in the evaluation of fusion after posterior lumbar interbody fusion surgery

Background context

Accurate evaluation of the postsurgery status of interbody fusion is important in deciding the patient's treatment. Dynamic plain radiographs are used as a convenient method, but the accuracy is not so good.

Purpose

This study aimed to evaluate the usefulness of dynamic flexion-extension radiographs as a method for evaluating fusion, by comparing it with three-dimensional thin-section computed tomography (CT).

Study design

Prospective controlled study.

Methods

We conducted a prospective study with 108 patients (158 levels) who, diagnosed with severe spinal stenosis and Grade I and Grade II spondylolisthesis, underwent posterior lumbar interbody fusion (PLIF) surgery, with follow-up by dynamic plain radiographs, functional rating scale, and three-dimensional (3D) thin-section CT for 1 year after surgery. In the plain radiographs, we looked for less than 3° of lordotic angle change, less than 3 mm of translation between vertebral bodies, and no presence of halo signs; satisfying all the criteria was regarded as fusion (Group A), whereas failure to satisfy any condition was referred to as probable nonfusion (Group B) and if none were satisfied as nonfusion (Group C). The patients were classified into fusion or nonfusion groups based on CT. Correlation between plain radiographs and CT groups was analyzed. Moreover, clinical assessment and cross-comparison between observers were done.

Results

In 158 levels, 95 (60.8%) levels were classified into the fusion group by plain radiographs and 131 (83%) levels by CT. When we analyzed the results of each groups, in Group A, 78 (81.3%) levels belonged to the CT fusion group and 18 (18.7%) levels to the CT nonfusion group, in Group B, 51 (89.5%) and 6 (10.5%) levels, and in Group C, 2 (40%) and 3 (60%) levels, respectively. For each of the CT fusion group, a cross-comparison using dynamic radiographs reconfirmed 78 (59.5%) levels for Group A, 51 (38.9%) levels for Group B, and 2 (1.6%) levels for Group C; for the CT nonfusion groups, 18 (66.7%) levels, 6 (22.2%) levels, and 3 (11.1%) levels were for Groups A, B, and C, respectively. In clinical evaluation, all groups showed clear postsurgery improvement, but there was no statistically significant difference. In terms of observer-to-observer error and agreement between diagnoses, CT showed a statistically higher level of correlation than plain radiographs.

Conclusions

Dynamic flexion-extension radiographs cannot be seen as an objective standard in the evaluation of fusion after PLIF surgery. It would be desirable to confirm the fusion status by thin-section 3D-CT for an objective analysis.     

Does the external remote controller’s reading correspond to the actual lengthening in magnetic-controlled growing rods?

Magnetic-controlled growing rods (MCGRs) are now routinely used in many centres to treat early-onset scoliosis (EOS). MCGR lengthening is done non-invasively by the external remote controller (ERC). Our experience suggests that there may be a discrepancy between the reported rod lengthening on the ERC and the actual rod lengthening. The aim of this study was to investigate this discrepancy. This was a prospective series. Eleven patients who were already undergoing treatment for EOS using MCGRs were included in this study. One hundred and ninety-two sets of ultrasound readings were obtained (96 episodes of rod lengthening on dual-rod constructs) and compared to their ERC readings. Only 15/192 (7.8%) readings were accurate; 27 readings (14.9%) were false positive; and 8 readings (4.2%) were an underestimation while 142 readings (74.0%) were an overestimation by the ERC. Average over-reporting by the ERC was 5.31 times of the actual/ultrasound reading. When comparing interval radiographs with lengthening obtained on ultrasound, there was a discrepancy with an average overestimation of 1.35 times with ultrasound in our series. There was a significant difference between ERC and USS (p = 0.01) and ERC and XR (p = 0.001). However, there was no significant difference between USS and XR (p > 0.99). The reading on the ERC does not equate to the actual rod lengthening. The authors would recommend that clinicians using the MCGR for the treatment of early-onset scoliosis include pre- and post-extension imaging (radiographs or ultrasound) to confirm extension lengths at each outpatient extension. In centres with ultrasound facilities, we would suggest that patients should have ultrasound to monitor each lengthening after distraction but also 6-month radiographs. These slides can be retrieved under Electronic Supplementary Material.     

Treatment of early-onset scoliosis with a hybrid of a concave magnetic driver (magnetic controlled growth rod) and a contralateral passive sliding rod construct with apical control: preliminary report on 17 cases

Background Context

Magnetic controlled growth rods (MCGRs) are increasingly popular for surgical treatment of severe early-onset scoliosis (EOS), because they allow noninvasive extensions with good growth maintenance. We combined an MCGR with a contralateral passive sliding rod construct with apical control on the convex side to improve efficiency in terms of costs and three-dimensional (3D) correction.

Cervical spine computed tomography utilization in pediatric trauma patients

Background

Guidelines for evaluating the cervical spine in pediatric trauma patients recommend cervical spine CT (CSCT) when plain radiographs suggest an injury. Our objective was to compare usage of CSCT between a pediatric trauma center (PTC) and referral general emergency departments (GEDs).

Methods

Patient data from a pediatric trauma registry from 2002 to 2011 were analyzed. Rates of CSI and CSCT of patients presenting to the PTC and GED were compared. Factors associated with use of CSCT were assessed using multivariate logistic regression.

Results

5148 patients were evaluated, 2142 (41.6%) at the PTC and 3006 (58.4%) at the GED. Groups were similar with regard to age, gender, GCS, and triage category. GED patients had a higher median ISS (14 vs. 9, p < 0.05) and more frequent ICU admissions (44.3% vs. 26.1% p < 0.05). CSI rate was 2.1% (107/5148) and remained stable. CSCT use increased from 3.5% to 16.1% over time at the PTC (mean 9.6% 95% CI = 8.3, 10.9) and increased from 6.8% to 42.0% (mean 26.9%, CI = 25.4, 28.4) at the GED. Initial care at a GED remained strongly associated with CSCT.

Conclusions

Despite a stable rate of CSI, rate of CSCT increased significantly over time, especially among patients initially evaluated at a GED.     

In vitro biomechanics of an expandable vertebral body replacement with self-adjusting end plates

Background context

Unstable burst fractures of the thoracolumbar spine may be treated surgically. Vertebral body replacements (VBRs) give anterior column support and, when used with supplemental fixation, impart rigidity to the injured segments. Although some VBRs are expandable, device congruity to the vertebral end plates is imprecise and may lead to stress risers and device subsidence.

Purpose

The objective of this study was to compare the rigidity of a VBR that self-adjusts to the adjacent vertebral end plates versus structural bone allograft and with an unsupported anterior column in a traumatic burst fracture reconstruction model.

Study design

Biomechanical flexibility testing with rod strain measurement.

Patient sample

Twelve T11–L3 human spine segments.

Outcome measures

Range of motion, neutral zone, and posterior fixation rod stress (moments).

Methods

Flexibility testing was performed to±6 Nm in flexion-extension, lateral bending, and axial rotation on 12 intact human T11–L3 specimens. Burst fractures were created in L1, and flexibility testing was repeated in three additional states: subtotal corpectomy with posterior instrumentation (PI) only from T12 to L2, reconstruction with a femoral strut allograft and PI, and reconstruction with a VBR (with self-adjusting end plates) and PI. The PI consisted of pedicle screws and strain gage instrumented rods that were calibrated to measure rod stress via flexion-extension bending moments.

Results

There was no statistical difference in range of motion or neutral zone between the strut graft and VBR constructs, which both had less motion than the PI-only construct in flexion/extension and torsion and were both less than the intact values in flexion/extension and lateral bending (p<.05). Posterior rod moments were significantly greater for the PI-only construct in flexion/extension relative to the strut graft and VBR states (p=.03).

Conclusions

This study, which simulated the immediate postoperative state, suggests that a VBR with self-adjusting end plate components has rigidity similar to the standard strut graft when combined with PI. Posterior rod stress was not significantly increased with this type of VBR compared with the strut graft reconstruction. The benefits of burst fracture stabilization using a self-adjusting VBR ultimately will not be known until long-term clinical studies are performed.     

Rods in spinal surgery: a review of the literature

Background context

Spinal instrumentation has been used for more than five decades. Since the introduction of the Harrington rod in 1962, new rod materials and concepts have been developed. Rigid rod fixation has achieved higher fusion rates than previous methods. Recently, semirigid rod fixation devices have been used for both dynamic stabilization and fusion fixation. Memory rods, which have an interesting ability to return to their pre-bent shape when the temperature increases, are expected to be used for scoliosis correction.

Purpose

To review the previous literature regarding biofunctionality and biocompatibility of rods in spinal surgery.

Conclusion

The properties of each type of rod need to be taken into consideration when performing spinal instrumentation surgery.     

Systematic review of the complications associated with magnetically controlled growing rods for the treatment of early onset scoliosis

Purpose

To analyse the complication profile of magnetically controlled growing rods (MCGRs) in early onset scoliosis (EOS).

Methods

This is a systematic review using PUBMED, Medline, Embase, Google Scholar and the Cochrane Library (keywords: MAGEC, Magnetically controlled growing rods and EOS) of all studies written in English with a minimum of five patients and a 1-year follow-up. We evaluated coronal correction, growth progression (T1–S1, T1–T12) and complications.

Results

Fifteen studies (336 patients) were included (42.5% male, mean age 7.9 years, average follow-up 29.7 months). Coronal improvement was achieved in all studies (pre-operative 64.8°, latest follow-up 34.9° p?=?0.000), as was growth progression (p?=?0.001). Mean complication rate was 44.5%, excluding the 50.8% medical complication rate. The unplanned revision rate was 33%. The most common complications were anchor pull-out (11.8%), implant failure (11.7%) and rod breakage (10.6%). There was no significant difference between primary (39.8%) and conversion (33.3%) procedures (p?=?0.462). There was a non-statistically significant increased complication rate with single rods (40 vs. 27% p?=?0.588).

Conclusions

MCGRs improve coronal deformity and maintain spinal growth, but carry a 44.5% complication and 33% unplanned revision rate. Conversion procedures do not increase this risk. Single rods should be avoided.

Graphical abstract

These slides can be retrieved under Electronic Supplementary material.

Open image in new window

     

Clinical adjacent-segment pathology after anterior cervical discectomy and fusion: results after a minimum of 10-year follow-up

Background context

Anterior cervical discectomy and fusion using cervical plates has been seen as effective at relieving cervical radiculopathy and myelopathy symptoms. Although it is commonly used, subsequent disc degeneration at levels adjacent to the fusion remains an important problem. However, data on the frequency, impact, and predisposing factors for this pathology are still rare.

Purpose

To evaluate the incidence, predisposing factors, and impact of radiographic and clinical adjacent-segment pathologies after anterior cervical discectomy and fusion using cervical plates and to analyze the efficacy of this surgical method over the long term, after a minimum follow-up period of 10 years.

Study design

Retrospective clinical study.

Patient sample

Our study was a retrospective analysis of 177 patients who underwent anterior cervical discectomy and fusion using cervical plates, with follow-up periods of at least 10 years (mean 16.2 years).

Outcome measures

Radiographic adjacent-segment pathology using plain radiographs and clinical adjacent-segment pathology after anterior cervical discectomy and fusion using cervical plates.

Methods

We defined a new grading system of plain radiographic evidence of degenerative changes in adjacent discs after anterior cervical discectomy and fusion using cervical plates; Grade 0 is considered normal, and Grade V consists the presence of posterior osteophytes and a decrease in disc height to less than 50% of normal. The incidence, predisposing factors, and impact of radiographic and clinical adjacent-segment pathologies were analyzed according to etiologies, number of fused segments, and plate-to-disc distance.

Results

Radiographic and clinical adjacent-segment pathologies were found in 92.1% and 19.2%, respectively, of patients. By etiology, clinical adjacent-segment pathology was observed in 13.5% of patients who had sustained trauma, 12.7% of those with disc herniation, and 33.3% of those with spondylosis. By number of fused segments, clinical adjacent-segment pathology was found in 13.2% of patients who underwent single-level fusion and in 32.1% of those who underwent multilevel fusion surgeries. Patients with a plate-to-disc distance of less than 5 mm, who had spondylosis, or who underwent multilevel fusion had a higher incidence of clinical adjacent-segment pathology after anterior cervical discectomy and fusion using cervical plates than other groups did (p<.05). Of all patients, only 6.8% needed follow-up surgery.

Conclusions

We found that over the long term, at a minimum follow-up point of 10 years, a plate-to-disc distance of less than 5 mm, having spondylosis, and undergoing multilevel fusion were predisposing factors for the occurrence of clinical adjacent-segment pathology. Nevertheless, the incidence of clinical findings of adjacent-segment pathology was much lower than the incidence of radiographic findings. Also, the rate of follow-up surgery was low. Therefore, anterior cervical discectomy and fusion using cervical plates can be considered a safe and effective procedure.     

Minimally invasive presacral retrieval of a failed AxiaLIF rod implant: technical note and illustrative cases

Background context

There are few reported cases of failed axial lumbar interbody fusion (AxiaLIF) in the existing neurosurgical literature, and an anecdotal case of open paramedian retroperitoneal approach to L5–S1 level for retrieval of AxiaLIF rod has been published.

Purpose

The object of this study is to illustrate a minimally invasive presacral rod retrieval technique in cases with failed AxiaLIF causing lumbosacral instability.

Study design/setting

Retrospective case series.

Methods

A retrospective analysis of the initial 26 cases of AxiaLIF done at our institution was performed; two cases of failed AxiaLIF that required rod removal were identified for detailed study. Available literature on the minimally invasive presacral techniques for rod retrieval was researched, and the use of a novel rod retrieval device with an expanding hex tip is discussed.

Results

Using a minimally invasive presacral approach through the previous surgical corridor, the authors were able to retrieve the AxiaLIF rod implant and then proceed with an alternative fusion technique. Both patients improved clinically and radiographically after revision. Removal of the presacral rod was not associated with vascular or bowel complications and required minimal operating room time with minimal blood loss.

Conclusions

To the authors' knowledge, this is the first report demonstrating the safety and efficacy of minimally invasive presacral approach for removal of AxiaLIF rods in patients with failed AxiaLIF. As the AxiaLIF procedure is rapidly gaining acceptance among spine surgeons, we can expect to see increasing numbers of failed procedures as well. Understanding options for revision strategies is important for surgeons considering the use of this technique.     

Biomechanics of lateral plate and pedicle screw constructs in lumbar spines instrumented at two levels with laterally placed interbody cages

Background context

The lateral transpsoas approach to interbody fusion is gaining popularity because of its minimally invasive nature and resultant indirect neurologic decompression. The acute biomechanical stability of the lateral approach to interbody fusion is dependent on the type of supplemental internal fixation used. The two-hole lateral plate (LP) has been approved for clinical use for added stabilization after cage instrumentation. However, little biomechanical data exist comparing LP fixation with bilateral pedicle screw and rod (PSR) fixation.

Purpose

To biomechanically compare the acute stabilizing effects of the two-hole LP and bilateral PSR fusion constructs in lumbar spines instrumented with a lateral cage at two contiguous levels.

Study design

Biomechanical laboratory study of human cadaveric lumbar spines.

Methods

Eighteen L1–S1 cadaveric lumbar spines were instrumented with lateral cages at L3–L4 and L4–L5 after intact kinematic analysis. Specimens (n=9 each) were allocated for supplemental instrumentation with either LP or PSR. Intact versus instrumented range of motion was evaluated for all specimens by applying pure moments (±7.5 Nm) in flexion/extension, lateral bending (LB) (left+right), and axial rotation (AR) (left+right). Instrumented spines were later subjected to 500 cycles of loading in all three planes, and interbody cage translations were quantified using a nonradiographic technique.

Results

Lateral plate fixation significantly reduced ROM (p<.05) at both lumbar levels (flexion/extension: 49.5%; LB: 67.3%; AR: 48.2%) relative to the intact condition. Pedicle screw and rod fixation afforded the greatest ROM reductions (p<.05) relative to the intact condition (flexion/extension: 85.6%; LB: 91.4%; AR: 61.1%). On average, the largest interbody cage translations were measured in both fixation groups in the anterior-posterior direction during cyclic AR.

Conclusions

Based on these biomechanical findings, PSR fixation maximizes stability after lateral interbody cage placement. The nonradiographic technique served to quantify migration of implanted hardware and may be implemented as an effective laboratory tool for surgeons and engineers to better understand mechanical behavior of spinal implants.     

Accuracy and reliability of coronal and sagittal spinal curvature data based on patient-specific three-dimensional models created by the EOS 2D/3D imaging system

Background context

Three-dimensional (3D) deformations of the spine are predominantly characterized by two-dimensional (2D) angulation measurements in coronal and sagittal planes, using anteroposterior and lateral X-ray images. For coronal curves, a method originally described by Cobb and for sagittal curves a modified Cobb method are most widely used in practice, and these methods have been shown to exhibit good-to-excellent reliability and reproducibility, carried out either manually or by computer-based tools. Recently, an ultralow radiation dose–integrated radioimaging solution was introduced with special software for realistic 3D visualization and parametric characterization of the spinal column.

Purpose

Comparison of accuracy, correlation of measurement values, intraobserver and interrater reliability of methods by conventional manual 2D and sterEOS 3D measurements in a routine clinical setting.

Study design/setting

Retrospective nonrandomized study of diagnostic X-ray images created as part of a routine clinical protocol of eligible patients examined at our clinic during a 30-month period between July 2007 and December 2009.

Patient sample

In total, 201 individuals (170 females, 31 males; mean age, 19.88 years) including 10 healthy athletes with normal spine and patients with adolescent idiopathic scoliosis (175 cases), adult degenerative scoliosis (11 cases), and Scheuermann hyperkyphosis (5 cases). Overall range of coronal curves was between 2.4° and 117.5°. Analysis of accuracy and reliability of measurements were carried out on a group of all patients and in subgroups based on coronal plane deviation: 0° to 10° (Group 1, n=36), 10° to 25° (Group 2, n=25), 25° to 50° (Group 3, n=69), 50° to 75° (Group 4, n=49), and more than 75° (Group 5, n=22).

Methods

Coronal and sagittal curvature measurements were determined by three experienced examiners, using either traditional 2D methods or automatic measurements based on sterEOS 3D reconstructions. Manual measurements were performed three times, and sterEOS 3D reconstructions and automatic measurements were performed two times by each examiner. Means comparison t test, Pearson bivariate correlation analysis, reliability analysis by intraclass correlation coefficients for intraobserver reproducibility and interrater reliability were performed using SPSS v16.0 software (IBM Corp., Armonk, NY, USA). No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this article.

Results

In comparison with manual 2D methods, only small and nonsignificant differences were detectable in sterEOS 3D–based curvature data. Intraobserver reliability was excellent for both methods, and interrater reproducibility was consistently higher for sterEOS 3D methods that was found to be unaffected by the magnitude of coronal curves or sagittal plane deviations.

Conclusions

This is the first clinical report on EOS 2D/3D system (EOS Imaging, Paris, France) and its sterEOS 3D software, documenting an excellent capability for accurate, reliable, and reproducible spinal curvature measurements.     

An analysis of radiographic parameters comparison between lumbar spine latericumbent and full-length lateral standing radiographs

Background Context

The lumbar spine latericumbent and full-length lateral standing radiographs are most commonly used to assess lumbar disorder. However, there are few literatures on the difference and correlation of the sagittal parameters between the two shooting positions.

How the spine differs in standing and in sitting—important considerations for correction of spinal deformity

Background Context

The current prevailing school of thought in spinal deformity surgery is to restore sagittal balance with reference to the alignment of the spine when the patient is standing. This strategy, however, likely accounts for increased rates of proximal junctional failure.

The (f)utility of flexion-extension C-spine films in the setting of trauma

Background

Flexion-extension radiographs are often used to assess for removal of the cervical collar in the setting of trauma. The objective of this study was to evaluate their adequacy. We hypothesized that a significant proportion is inadequate.

Methods

This was a retrospective review of C-spine clearance at a level 1 trauma center. A trauma-trained radiologist interpreted all flexion-extension radiographs for adequacy. Studies performed within 7 days of injury were considered acute.

Results

Three hundred fifty-five flexion-extension radiographs were examined. Ninety-five percent% of these studies were inadequate (51% because of the inability to visualize the top of T1, whereas 44% had less than 30° of angulation from neutral). Two hundred ten studies were performed acutely; of these, 97% were inadequate. When performed 7 days or longer from injury, 91% were inadequate.

Conclusions

Injury to the C-spine may harbor significant consequences; therefore, its proper evaluation is critical. The majority of flexion-extension films are inadequate. As such, they should not be included in the algorithm for removal of the cervical collar. If used, adequacy must be verified and supplemental radiographic studies obtained as indicated.     

Bowel symptoms in children with anorectal malformation — a follow-up with a gender and age perspective

Background

Gender specific outcome for children with anorectal malformations (ARM) is rarely reported although it is important for medical care and in parent counseling.

Purpose

To assess bowel function according to the Krickenbeck system in relation to ARM-subtype, gender and age.

Method

All children born with ARM in 1998–2008 and referred to two centers in two different countries were followed up. The bowel function in 50 girls and 71 boys, median age 8 years, was analyzed.

Results

Among those with a perineal fistula, incontinence occurred in 42% of the females and in 10% of the males (p = 0.005) whereas constipation occurred in 62% of the females and 35% of the males (p < 0.001). No bowel symptoms differed between the females with perineal and vestibular fistulas (p > 0.3 for every symptom). Sacral malformations were associated with incontinence only in males with rectourethral fistulas. Constipation among the males differed between the age groups: 58% versus 26% (p = 0.013). Bowel symptoms did not change with age among the females.

Conclusion

Gender differences in outcome for children with ARM must be considered. Males with perineal fistulas had less incontinence and constipation than the females with perineal fistulas. The females with perineal and vestibular fistulas had similar outcomes.     

Novel technique of reduction of a chronic atlantoaxial rotatory fixation using a temporary transverse transatlantal rod

Background context

Chronic atlantoaxial rotatory fixation (AARF) is uncommon as acute AARF is easily reduced either spontaneously or by conservative methods. Various anterior and posterior surgical approaches for a chronic AARF have been reported because of the difficulty encountered in obtaining reduction.

Purpose

To describe a novel technique of reduction of a chronic AARF using a temporary transverse transatlantal rod.

Study design

Technical report.

Methods

A 13-year-old girl presented with an 8-month-old chronic AARF with typical torticollis and “cock-robin” posture of the head with a normal neurology. As closed reduction with skull traction for 2 weeks failed to reduce the deformity, the patient underwent C1–C2 fusion. C1 lateral mass and C2 pedicle screws were inserted under computer navigation. A temporary transverse rod across the atlas and axis was placed to secure a three-column fixation to derotate the subluxed atlas into anatomical alignment. Rods were then connected between the C1 lateral masses and the C2 pedicle screws and fusion obtained with autologous iliac crest grafts.

Result

Anatomic reduction of the atlantoaxial region was obtained without neural compromise, and satisfactory fusion was observed at 6-months follow-up.

Conclusion

A temporary transatlantal rod provides a secure anchor point for easy maneuverability for reduction of a chronic AARF and has the advantage of being used even in the absence of the posterior arch of the atlas.     

A pilot cadaveric study of temperature and adjacent tissue changes after exposure of magnetic-controlled growing rods to MRI

Purpose

To test for possible thermal injury and tissue damage caused by magnetic-controlled growing rods (MCGRs) during MRI scans.

Methods

Three fresh frozen cadavers were utilized. Four MRI scans were performed: baseline, after spinal hardware implantation, and twice after MCGR implantation. Cross connectors were placed at the proximal end and at the distal end of the construct, making a complete circuit hinged at those two points. Three points were identified as potential sites for significant heating: adjacent to the proximal and distal cross connectors and adjacent to the actuators. Data collected included tissue temperatures at baseline (R1), after screw insertion (R2), and twice after rod insertions (R3 and R4). Tissue samples were taken and stained for signs of heat damage.

Results

There was a slight change in tissue temperature in the regions next to the implants between baseline and after each scan. Average temperatures (°C) increased by 0.94 (0.16–1.63) between R1 and R2, 1.6 (1.23–1.97) between R2 and R3, and 0.39 (0.03–0.83) between R3 and R4. Subsequent histological analysis revealed no signs of heat induced damage.

Conclusion

Recurrent MRI scans of patients with MCGRs may be necessary over the course of treatment. When implanted into human cadaveric tissue, these rods appear to not be a risk to the patient with respect to heating or tissue damage. Further in vivo study is warranted.

Level of evidence

N/A.

     

Clinical validation of coronal and sagittal spinal curve measurements based on three-dimensional vertebra vector parameters

Background context

For many decades, visualization and evaluation of three-dimensional (3D) spinal deformities have only been possible by two-dimensional (2D) radiodiagnostic methods, and as a result, characterization and classification were based on 2D terminologies. Recent developments in medical digital imaging and 3D visualization techniques including surface 3D reconstructions opened a chance for a long-sought change in this field. Supported by a 3D Terminology on Spinal Deformities of the Scoliosis Research Society, an approach for 3D measurements and a new 3D classification of scoliosis yielded several compelling concepts on 3D visualization and new proposals for 3D classification in recent years. More recently, a new proposal for visualization and complete 3D evaluation of the spine by 3D vertebra vectors has been introduced by our workgroup, a concept, based on EOS 2D/3D, a groundbreaking new ultralow radiation dose integrated orthopedic imaging device with sterEOS 3D spine reconstruction software.

Purpose

Comparison of accuracy, correlation of measurement values, intraobserver and interrater reliability of methods by conventional manual 2D and vertebra vector–based 3D measurements in a routine clinical setting.

Study design

Retrospective, nonrandomized study of diagnostic X-ray images created as part of a routine clinical protocol of eligible patients examined at our clinic during a 30-month period between July 2007 and December 2009.

Patient sample

In total, 201 individuals (170 females, 31 males; mean age, 19.88 years) including 10 healthy athletes with normal spine and patients with adolescent idiopathic scoliosis (175 cases), adult degenerative scoliosis (11 cases), and Scheuermann hyperkyphosis (5 cases). Overall range of coronal curves was between 2.4 and 117.5°. Analysis of accuracy and reliability of measurements was carried out on a group of all patients and in subgroups based on coronal plane deviation: 0 to 10° (Group 1; n=36), 10 to 25° (Group 2; n=25), 25 to 50° (Group 3; n=69), 50 to 75° (Group 4; n=49), and above 75° (Group 5; n=22).

Methods

All study subjects were examined by EOS 2D imaging, resulting in anteroposterior (AP) and lateral (LAT) full spine, orthogonal digital X-ray images, in standing position. Conventional coronal and sagittal curvature measurements including sagittal L5 vertebra wedges were determined by 3 experienced examiners, using traditional Cobb methods on EOS 2D AP and LAT images. Vertebra vector–based measurements were performed as published earlier, based on computer-assisted calculations of corresponding spinal curvature. Vertebra vectors were generated by dedicated software from sterEOS 3D spine models reconstructed from EOS 2D images by the same three examiners. Manual measurements were performed by each examiner, thrice for sterEOS 3D reconstructions and twice for vertebra vector–based measurements. Means comparison t test, Pearson bivariate correlation analysis, reliability analysis by intraclass correlation coefficients for intraobserver reproducibility and interrater reliability were performed using SPSS v16.0 software.

Results

In comparison with manual 2D methods, only small and nonsignificant differences were detectable in vertebra vector–based curvature data for coronal curves and thoracic kyphosis, whereas the found difference in L1–L5 lordosis values was shown to be strongly related to the magnitude of corresponding L5 wedge. Intraobserver reliability was excellent for both methods, and interrater reproducibility was consistently higher for vertebra vector–based methods that was also found to be unaffected by the magnitude of coronal curves or sagittal plane deviations.

Conclusions

Vertebra vector–based angulation measurements could fully substitute conventional manual 2D measurements, with similar accuracy and higher intraobserver reliability and interrater reproducibility. Vertebra vectors represent a truly 3D solution for clear and comprehensible 3D visualization of spinal deformities while preserving crucial parametric information for vertebral size, 3D position, orientation, and rotation. The concept of vertebra vectors may serve as a starting point to a valid and clinically useful alternative for a new 3D classification of scoliosis.