Radiographic measurement of the sagittal plane deformity in patients with osteoporotic spinal fractures evaluation of intrinsic error

Spinopelvic measurements of sagittal balance with deep learning: systematic review and critical evaluation

PURPOSE

To summarize and critically evaluate the existing studies for spinopelvic measurements of sagittal balance that are based on deep learning (DL).

METHODS

Three databases (PubMed, WoS and Scopus) were queried for records using keywords related to DL and measurement of sagittal balance. After screening the resulting 529 records that were augmented with specific web search, 34 studies published between 2017 and 2022 were included in the final review, and evaluated from the perspective of the observed sagittal spinopelvic parameters, properties of spine image datasets, applied DL methodology and resulting measurement performance.

RESULTS

Studies reported DL measurement of up to 18 different spinopelvic parameters, but the actual number depended on the image field of view. Image datasets were composed of lateral lumbar spine and whole spine X-rays, biplanar whole spine X-rays and lumbar spine magnetic resonance cross sections, and were increasing in size or enriched by augmentation techniques. Spinopelvic parameter measurement was approached either by landmark detection or structure segmentation, and U-Net was the most frequently applied DL architecture. The latest DL methods achieved excellent performance in terms of mean absolute error against reference manual measurements (~ 2° or ~ 1 mm).

CONCLUSION

Although the application of relatively complex DL architectures resulted in an improved measurement accuracy of sagittal spinopelvic parameters, future methods should focus on multi-institution and multi-observer analyses as well as uncertainty estimation and error handling implementations for integration into the clinical workflow. Further advances will enhance the predictive analytics of DL methods for spinopelvic parameter measurement.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

A Comparative Study on the Treatment of Osteoporotic Vertebral Compression Fractures With Early Ambulation and at Least 1 Week of Absolute Bed Rest

Objective

This study aimed to determine whether absolute bed rest (ABR) is essential for the conservative treatment of osteoporotic vertebral compression fractures (OVCFs).

Methods

This study included 115 patients diagnosed with OVCFs. The patients in group A were allowed to ambulate as soon as possible, while those in group B underwent ABR for at least 1 week. X-ray images at baseline and 1 week, 2 weeks, 1 month, 3 months, and 6 months after trauma were obtained from both groups for assessment. In each group, ABR-related complications including constipation, indigestion, Foley catheter insertion, urinary tract infection, cough/sputum, dizziness, and neurasthenia were investigated.

Results

In both groups, the compression rates, Cobb angles, and visual analog scale scores did not differ significantly at baseline and the first, second, third, fourth, and fifth follow-ups. In terms of constipation, indigestion, dizziness, and neurasthenia, group A reported a significantly higher complication rate than group B (p<0.05).

Conclusion

The prognosis did not differ significantly between patients who underwent ABR for at least 1 week and those who started walking as soon as possible. The incidence of complications due to ABRs was lower in the early ambulatory group. Therefore, it may be helpful to start walking as early as possible during the conservative treatment of OVCFs.

Differences in surgical outcome after anterior corpectomy and reconstruction with an expandable cage with rectangular footplates between thoracolumbar and lumbar osteoporotic vertebral fracture

Background

Anterior and posterior spinal fixation (APSF) can provide rigid structural anterior column support in patients with osteoporotic vertebral fracture (OVF). A new rectangular footplate designed based on biomechanical studies of endplates provides better resistance to subsidence. However, differences in characteristics exist between the thoracolumbar and lower lumbar spine. The purpose of this study was to evaluate the surgical outcomes following APSF using an expandable cage with rectangular footplates in the thoracolumbar/lumbar region.

Methods

Consecutive patients who underwent APSF for OVF at multiple centers were retrospectively reviewed. Clinical and radiographic evaluations were performed by dividing the patients into thoracolumbar (TL, T10–L2) and lumbar (L, L3–L5) groups. Surgical indications were incomplete neurologic deficit or intractable back pain with segmental spinal instability. Surgical outcomes including the Japanese Orthopaedic Association (JOA) score and reoperation rate were compared between TL and L groups.

Results

Sixty-nine patients were followed-up for more than 12 months and analyzed. Operative intervention was required for 35 patients in the TL group and 34 patients in the L group. Mean ages in the TL and L groups were 76.5 years and 75.1 years, respectively. Intra-vertebral instability was more frequent in the TL group (p<0.001). Screw fixation range was significantly longer in the TL group (p=0.012). The rate of cage subsidence did not differ significantly between the TL group (46%) and L group (44%). Reoperation rate tended to be higher in the TL group (p=0.095). Improvement ratio of JOA score was significantly better in the L group (60%) than in the TL group (46.9%, p=0.029).

Conclusion

APSF using an expandable cage was effective to treat OVF at both lumbar and thoracolumbar levels. However, the improvement ratio of the JOA score was better in the L group than in the TL group.

Thoracic kyphosis assessment in postmenopausal women: an examination of the Flexicurve method in comparison to radiological methods

The Flexicurve ruler is an alternative method to radiographs for measuring thoracic kyphosis (curvature), but it is not certain that it is comparable. This study shows that Flexicurve can estimate radiographic vertebral centroid angles with less error than Cobb angles but that its accuracy would be inadequate for most clinical purposes.

INTRODUCTION

The Flexicurve ruler provides a non-radiological method of measuring thoracic kyphosis (TK) that has moderately strong correlations with the gold-standard radiographic Cobb angle method, while consistently underestimating the TK angle. Cobb angles can include measurement errors that may contribute to poor agreement, particularly in older populations. The vertebral centroid angle could be a better radiographic reference method for the validation of Flexicurve. Using two separate radiographic measurements of TK, we examined the validity of Flexicurve. We aimed to ascertain the level of agreement between measures and to empirically explore reasons for between-method differences.

METHODS

TK angles determined using Flexicurve and radiographic Cobb and vertebral centroid methods were compared using data from 117 healthy postmenopausal women (mean (SD) age 61.4 (7.0) years). Bland and Altman plots were used to assess differences between methods. Age, bone mineral density and body mass index were examined as characteristics that might explain any differences.

RESULTS

Flexicurve angles were scaled prior to analysis. There was no statistically significant difference between angles produced by Flexicurve and vertebral centroid methods (MD - 2.16°, 95%CI - 4.35° to 0.03°) although differences increased proportionally with TK angles. Flexicurve angles were significantly smaller than radiographic Cobb angles and depending on the scaling method used, systematic error ranged between - 2.48° and - 5.19°. Age accounts for some of the differences observed (R² < 0.08, p < 0.005).

CONCLUSIONS

TK measured using the Flexicurve shows better agreement with the radiographic vertebral centroid method, but inaccuracy of the Flexicurve increases with increasing angle of kyphosis.

The Outcome of Radiofrequency Kyphoplasty in the Treatment of Vertebral Compression Fractures in Osteoporotic Patients

Study Design

Retrospective study.

Purpose

The study aims to assess the effectiveness and safety of radiofrequency (RF) kyphoplasty in the treatment of vertebral compression fractures (VCFs) in osteoporotic patients.

Overview of Literature

Vertebroplasty and balloon kyphoplasty are established procedures for the treatment of osteoporotic VCFs. However, RF kyphoplasty is a new method which controls cement viscosity.

Methods

We reviewed the results of 41 consecutive patients with 23 thoracic and 38 lumbar VCFs who underwent RF kyphoplasty. The study population included 14 males (34%) and 27 females (66%). The mean patients age was 78 years (range, 51–89 years), and the follow-up period was 1 year. Clinical and radiographic analyses were performed during follow-up at 6 weeks, 6 months, and 1 year. All patients were assessed clinically pre- and postoperative using the Visual Analog Scale (VAS) and Oswestry Disability Index (ODI). Radiological assessment with X-ray in two views preoperatively, postoperatively, and during follow-up visits.

Results

The mean preoperative VAS was 8.7 (range, 5–10; standard deviation [SD], 1.2). Postoperatively, VAS decreased by 3.3 (range, 2–5; SD, 0.9). At the end of the follow-up, VAS decreased by 1.22 (range, 0–7; SD, 1.6). The mean preoperative ODI score was 85.9, decreasing to 9.6 postoperatively and improving to 18.4 during the 1-year follow-up. The mean local kyphotic angle was 9.04° before the procedure and decreased by a mean of 6.16° after the operation and at the end of the follow-up. The mean increase in vertebral body height was 3.3 mm postoperatively and after 1-year follow-up. The rate of cement leakage was 8% (five out of 61 levels of fracture).

Conclusions

RF kyphoplasty is a safe and effective augmentation technique with an advantage of controlling the cement viscosity to minimize the risk of cement leakage. It also shortens operation time.

Acute traumatic intraosseous fluid sign predisposes to dynamic fracture mobility

The intraosseous fluid sign (IFS) in chronic osteoporotic vertebral fractures is attributed to fluid accumulation within non-healing intervertebral clefts. IFS can also be seen in acute traumatic fractures, not previously described. We hypothesize a pathophysiological mechanism for the acute traumatic intraosseous fluid sign (ATIFS) and its predisposition to dynamic fracture mobility with axial loading on upright radiographs. Retrospective analysis was performed of 41 acute thoracic and lumbar compression or stable burst fractures with both supine CT and upright plain films completed within 1 week of each other. The presence of an intravertebral cleft with fluid attenuation and vertebral body height loss was assessed on CT scans. Changes in the fractured vertebral body height and angulation were measured on upright radiographs. The ATIFS was identified in 18 (44%) of the 41 acute fractures. Mean kyphotic angle increase was significantly greater (p = 0.000) for ATIFS fractures (8.2°, SD ±4.2) than fractures without ATIFS (1.6°, SD ±3.4). There was significantly greater mean anterior (p = 0.0009) and central (p = 0.026) height loss in ATIFS fractures (4.3 mm, SD ±3.76 and 1.89 mm, SD ±4.44, respectively) compared to fractures without ATIFS (0.59 mm, SD ±2.24 and -0.52 mm, SD ±2.01, respectively). The IFS can be seen in acute traumatic vertebral fractures and show dynamic mobility. These ATIFS fractures show statistically significant greater mean height loss ratio differences and have significantly greater changes in kyphotic angulation on upright imaging when compared to fractures without ATIFS.

Vertebral body morphology is associated with incident lumbar vertebral fracture in postmenopausal women. The OFELY study

We investigate the predictive role of vertebral anterior cortical curvature and height heterogeneity in the occurrence of vertebral fractures in postmenopausal women. Women who will fracture had shorter vertebral height, greater heterogeneity of height than those who will not fracture, and their anterior vertebral body edge was less concave.

INTRODUCTION

Vertebral morphology has been demonstrated to be associated with further risk of fracture. The aim of this study was to analyze vertebral anterior cortical curvature (Ct.curv) and vertebral height heterogeneity in postmenopausal women before the occurrence of a vertebral fracture.

METHODS

This case-control study included 29 postmenopausal women who have underwent incident lumbar vertebral fractures (mean age 71 ± 9 years, mean time to fractures 9 ± 4 years), age-matched with 57 controls. From lateral X-rays of lumbar spine radiographs (T12 to L4), the following parameters were measured: (1) the posterior, middle, and anterior vertebral heights; (2) the heterogeneity of heights evaluated by the coefficient of variation of these three variables; (3) antero-posterior width, a 2D estimator of cross-sectional area; and (4) Ct.curv.

RESULTS

Mean vertebral heights were significantly lower among women who fractured than in controls (p < 0.05). The anterior and middle heights were significantly lower at L4 and L3 levels in fracture group (p = 0.02). The heterogeneity of vertebral height was significantly greater in the fracture group (p = 0.003). In addition, fractured patients had a significantly higher Ct.curv on L3 (p = 0.04). After adjustment for bone mineral density (BMD), only the heterogeneity of vertebral height remained significant (p = 0.005).

CONCLUSION

The current case-control study confirmed the association between vertebral height and occurrence of future vertebral fracture in postmenopausal women. The vertebrae with the smallest Ct.curv tended to fracture less often, and the heterogeneity of vertebral heights was associated with future fracture independently of BMD. An additional validation in a prospective study would be needed to confirm these initial results.

Clinical Effects and Radiological Results of Vertebroplasty: Over a 2-year Follow-Up Period

Objective

We investigated the association between clinical and radiological results and assessed the radiological changes according to the distribution pattern and amount of injected cement after vertebroplasty.

Methods

Two hundred and one patients underwent vertebroplasty; of these, 15 were follow up for more than 2 years. For radiological analysis, we grouped the patients according to cement distribution as follows: group 1, unilateral, unilateral distribution of cement; group 2, bilateral-uneven, bilateral distribution of cement but separated mass; and group 3, bilateral-even, bilateral single mass of cement. To compare radiologic with clinical results, we assessed the visual analogue scale (VAS) score, amount of injected cement, bone mineral density (BMD), postoperative and follow-up vertebral body compression ratios, and postoperative and follow-up kyphotic angles.

Results

There were 4 (26.7%) patients in group 1, 6 (40.0%) in group 2, and 5 (33.3%) in group 3. The mean VAS score was 5.2 preoperatively, 1.8 postoperatively, and 3.2 at 2-year follow-up. The 2-year follow-up compression ratio was better in patients with even distribution of injected cement (group 2 and 3) than group 1. However, it was not statistically insignificant (p>0.05). The follow-up kyphotic angle was more aggravated in the group 1 than in the other groups (p<0.05).

Conclusion

Our study showed that vertebroplasty had a beneficial effect on pain relief, particularly in the immediate postoperative stage. The augmented spine tended to be more stable in the cases with increased amount and more even distribution of injected cement.

Inter- and intraobserver agreement on the Load Sharing Classification of thoracolumbar spine fractures

The Load Sharing Classification (LSC) allocates one to three points to each of three different radiological characteristics of traumatic thoracolumbar fractures: the vertebral body involved in the fracture, the displacement of the fracture parts and the kyphotic deformity. Added up, a minimal score of three and a maximal score of nine can be obtained. When the LSC score is three to six, a short segment pedicle screw fixation suffices. When the LSC score is seven to nine, a high rate of failure in patients with a short segment pedicle screw fixation exists. In these cases an anterior stabilising procedure of the spine is advised. The LSC has been examined by Dai and Jin, who claim an almost perfect inter- and intraobserver agreement, according to the Landis and Koch criteria. Dai and Jin only present results for the separate three items of the LSC and for the total LSC scores. Observer agreement for the two LSC score categories (three to six and seven to nine) have not been studied. The aim of this study is to study the inter- and intraobserver agreement of the LSC for the total score, the three separate items and also for the two LSC score categories. Three observers determine twice the LSC scores of forty traumatic thoracolumbar fractures. The average standard Cohen's kappa values for the separate LSC items range between 0.06 and 0.48. For the total LSC score the average standard Cohen's kappa and weighted kappa values are 0.22 and 0.67 respectively. For the two LSC score categories, there is unanimous agreement in 55% of the cases and a majority agreement in 40%. In the remaining 5% of the fractures there is a split decision. Standard Cohen's kappa value for the two LSC score categories is 0.53. The standard Cohen's kappa values can be rated as fair to moderate. From these data it can be concluded that the inter- and intraobserver reliability of the Load Sharing Classification of Spinal fractures can be rated as fair.

Estudio comparativo del tratamiento ortésico en las fracturas toraco-lumbosacras según la gravedad del trauma

OBJETIVO: Determinar si la gravedad del trauma en lesiones toracolumbosacras mayores estables permite decidir la selección del tipo de ortesis en un tratamiento ortopédico. MÉTODOS: Estudio Retrospectivo de casos 12/1990 - 12/2006 (16 años). Criterios de Selección: 1) Seguimiento mínimo: 2 años. 2) Estudios radiológicos convencionales completos. 3) Ausencia de Litigio. 4) Tratamiento ortésico con TLSO a medida para los traumas de alta energía cinética y con ortesis prefabricadas para los de baja energía. 5) Tratamiento efectuado o supervisado por el autor Sénior. Evaluación por observadores independientes de Parámetros Geométricos (ángulo de Cobb sagital, cifosis vertebral, grado de colapso vertebral) pretratamiento y seguimiento en Rx simple, y Parámetros Funcionales (Dolor según SRS, Índice de Oswestry, Retorno a la Actividad Previa). Subdivisión de los diferentes tipos de fracturas (según AO y Denis) en Alta (Grupo A) y Baja Energía [Grupo B] de acuerdo con la energía cinética del trauma. Comparación de Parámetros Geométricos con Grupo Control. Análisis Estadístico: chi cuadrado y t-test de Student. RESULTADOS: 41 pacientes (44 fracturas] tratados (23 mujeres/18 varones), con 25 fracturas Grupo "A", y 19 Grupo "B". Edad promedio: 46 años (12 - 83). Seguimiento promedio: 4,5 años (2.2 - 15.5). Localización predominante: T11 - L2. Tipos Predominantes: tipo A (AO) o por compresión y por estallido. No hubo diferencias significativas en las mediciones efectuadas en cada grupo pretratamiento y al seguimiento. La única diferencia significativa entre grupos fue en la cifosis vertebral inicial tanto en general como según la clasificación AO entre los tipos A de alta y baja energía. La comparación al seguimiento de los parámetros geométricos entre grupo control y grupos A y B así como entre grupo control y cada tipo (AO/Denis) subdivididos en alta o baja energía, arrojó siempre diferencias significativas. Los parámetros funcionales al seguimiento mostraron siempre puntuaciones promedio buenas, con variaciones significativas entre grupos A y B. El retorno a la actividad previa fue del 90,6%, sin diferencias entre trabajadores de esfuerzo físico y de escritorio. CONCLUSIONES: Es posible lograr un Resultado Clínico Funcional satisfactorio a mediano plazo en las lesiones toracolumbosacras mayores estables seleccionando el tipo de ortesis según que el trauma sea de alta o baja energía cinética. Los resultados clínicos funcionales parecen ser mejores en los casos de Trauma de Alta Energía. Sin embargo, este tratamiento no mejora ni empeora los parámetros radiológicos sagitales.

A review of methods for quantitative evaluation of spinal curvature

The aim of this paper is to provide a complete overview of the existing methods for quantitative evaluation of spinal curvature from medical images, and to summarize the relevant publications, which may not only assist in the introduction of other researchers to the field, but also be a valuable resource for studying the existing methods or developing new methods and evaluation strategies. Key evaluation issues and future considerations, supported by the results of the overview, are also discussed.