A modified sagittal spine postural classification and its relationship to deformities and spinal mobility in a chinese osteoporotic population

Marker-Based Versus IMU-Based Kinematics for Estimates of Lumbar Spine Loads Using a Full-Body Musculoskeletal Model

Musculoskeletal modeling, typically implemented using marker-based systems in laboratory environments, is commonly used for noninvasive estimations of loads. Inertial measurement units (IMUs) have become an alternative for the evaluation of kinematics. However, estimates of spine joint contact forces using IMUs have yet to be thoroughly evaluated. Dynamics tasks and static postures from activities of daily living were captured on 11 healthy subjects using both systems simultaneously. Spine kinematics obtained from IMU- and marker-based systems and L4-L5 joint contact forces were compared. Lateral bending resulted in a weak agreement with significant differences between the 2 systems (P = .02, average root mean-squared error = 4.81), whereas flexion-extension and axial rotation exhibited the highest agreement with no significant differences (P < .05, average root mean-squared error = 5.51 and P < .31, average root mean-squared error = 5.08, respectively). All tasks showed excellent correlations (R2 = .76-.99) in estimated loads between systems. Differences in predicted loads at the L4-L5 were only observed during flexion-extension (1041 N vs 947 N, P = .0004) and walking with weights (814 N vs 727 N, P = .004). Different joint reaction force outcomes were obtained in 2 of the 8 tasks between systems, suggesting that IMUs can be robust tools allowing for convenient and less expensive evaluations and for longitudinal assessments inside and outside the laboratory setting.

Relationship of total sagittal spinal alignment index of thoracic kyphosis and lumbar lordosis with physical function in community-dwelling older adults

BACKGROUND

Overall spinal curvature is evaluated by calculating the difference between the angles of lumbar lordosis (LL) and thoracic kyphosis (TK) and is expressed as LL minus TK (LL-TK). It is unclear whether LL-TK is associated with physical function in community-dwelling older adults and whether it is more relevant than TK or LL alone.

OBJECTIVE

This study aimed to identify whether LL-TK is associated with physical function in community-dwelling older adults, and whether it is strongly associated than TK or LL alone.

METHODS

The participants comprised 1,674 community-dwelling older adults who underwent physical assessments (women, n = 1,099; mean age, 67.4 ± 5.3 years). As spinal alignment indices, TK and LL were measured using skin surface methods, and LL-TK was calculated as the difference between them. Decreased LL-TK indicated increased overall spinal curvature. Physical function was determined by measuring single-leg standing, five-times chair-stand, and usual gait speed. Stepwise multiple regression analyses were performed with each physical function as the dependent variable and spinal alignment indices as the independent variables, with adjustments.

RESULTS

Multiple regression analyses showed that single-leg standing (β = 0.092, 95% confidence interval [CI] = 0.071 to 0.214, p < .001) and five-times chair-stand (β=-0.142, 95% CI = -0.037 to -0.019, p < .001) were significantly associated with LL-TK, but not LL. Both LL-TK (β = 0.121, 95% CI = 0.001 to 0.004, p < .001) and LL (β = 0.087, 95% CI = 0.001 to 0.003, p = .003) were significant determinants of usual gait speed.

CONCLUSIONS

This study showed that decreased LL-TK may be associated with poor physical function. This association may be stronger than that observed for TK or LL alone.

Spinal posture, mobility, and position sense in adolescents with chest wall deformities: a comparison of pectus excavatum, pectus carinatum and healthy peers

PURPOSE

The study aimed to compare spinal posture, mobility, and position sense in adolescents with pectus excavatum (PE), pectus carinatum (PC), and healthy control (HC).

METHODS

22 with PE, 22 with PC, and 21 HC were included in the study. The spinal posture (thoracic kyphosis, lumbar lordosis, pelvic tilt, thoracic, lumbar, pelvic lateral tilt angles) and mobility (thoracic, lumbar, hip/sacral, and overall, in the sagittal and frontal plane) with the spinal mouse, and spinal position sense (repositing errors) with the inclinometer were assessed.

RESULTS

The thoracic kyphosis angle of PE and PC was higher than in HC (p < 0.001; p = 0.001). Hip/sacral mobility in the sagittal plane was lower in the PE and PC than control, respectively (p < 0.001; p < 0.001). Overall sagittal spinal mobility (p:0.007) and hip/sacral mobility in the frontal plane (p:0.002) were lower in the PC than in HC. Overall frontal spinal mobility was lower in the PE and PC than in HC (p:0.002; p:0.014). The PE and PC repositing errors were higher (p < 0.001; p:0.014).

CONCLUSION

The study found that adolescents with PE and PC had decreased spinal mobility, spinal alignment disorders, and a decline in spinal position sense. It is important not to overlook the spine during physical examinations of adolescents with chest wall deformities. In clinical practice, we suggest that adolescents with chest deformities should undergo a spine evaluation and be referred for physical therapy to manage spinal disorders.

Sagittal Spinal Alignment in People with Chronic Spinal Cord Injury and Normal Individual: A Comparison Study Using 3D Ultrasound Imaging

The aim of this study was to compare the sagittal spinal alignment of people with chronic spinal cord injury (SCI) with normal individuals and to determine whether transcutaneous electrical spinal cord stimulation (TSCS) could cause a change in the thoracic kyphosis (TK) and lumbar lordosis (LL) to re-establish normal sagittal spinal alignment. A case series study was conducted, wherein twelve individuals with SCI and ten neurologically intact subjects were scanned using 3D ultrasonography. In addition, three people with SCI having complete tetraplegia participated further to receive a 12-week treatment (TSCS with task-specific rehabilitation) after evaluation of sagittal spinal profile. Pre- and post-assessments were conducted to evaluate the differences in sagittal spinal alignment. The results showed that the TK and LL values for a person with SCI in a dependent seated posture were greater than those of normal subjects for: standing (by TK: 6.8° ± 1.6°; LL: 21.2° ± 1.9°), sitting straight (by TK: 10.0° ± 4.0°; LL: 1.7° ± 2.6°), and relaxed sitting (by TK: 3.9° ± 0.3°; LL: 7.7° ± 1.4°), respectively, indicating an increased risk for spinal deformity. In addition, TK decreased by 10.3° ± 2.3° after the TSCS treatment, showing a reversible change. These results suggest that the TSCS treatment could be used to restore normal sagittal spinal alignment for individuals with chronic SCI.

Analysis of the Active Measurement Systems of the Thoracic Range of Movements of the Spine: A Systematic Review and a Meta-Analysis

(1) Objective: to analyze current active noninvasive measurement systems of the thoracic range of movements of the spine. (2) Methods: A systematic review and meta-analysis were performed that included observational or clinical trial studies published in English or Spanish, whose subjects were healthy human males or females ≥18 years of age with reported measurements of thoracic range of motion measured with an active system in either flexion, extension, lateral bending, or axial rotation. All studies that passed the screening had a low risk of bias and good methodological results, according to the PEDro and MINORS scales. The mean values and 95% confidence interval of the reported measures were calculated for different types of device groups. To calculate the differences between the type of device measures, studies were pooled for different types of device groups using Review Manager software. (3) Results: 48 studies were included in the review; all had scores higher than 7.5 over 10 on the PEDro and MINORs methodological rating scales, collecting a total of 2365 healthy subjects, 1053 males and 1312 females; they were 39.24 ± 20.64 years old and had 24.44 ± 3.81 kg/m2 body mass indexes on average. We summarized and analyzed a total of 11,892 measurements: 1298 of flexoextension, 1394 of flexion, 1021 of extension, 491 of side-to-side lateral flexion, 637 of right lateral flexion, 607 of left lateral flexion, 2170 of side-to-side rotation, 2152 of right rotation and 2122 of left rotation. (4) Conclusions: All collected and analyzed measurements of physiological movements of the dorsal spine had very disparate results from each other, the cause of the reason for such analysis is that the measurement protocols of the different types of measurement tools used in these measurements are different and cause measurement biases. To solve this, it is proposed to establish a standardized measurement protocol for all tools.

Does passive hip stiffness or range of motion correlate with spinal curvature and posture during quiet standing?

BACKGROUND

It has been postulated that hip muscle stiffness can be inferred from postural assessment, and that predictable relationships exist between passive stiffness of opposing muscles. Despite a lack of evidence to demonstrate such relationships, manual therapy textbooks continue to direct clinicians to treat hip muscles following postural analysis.

RESEARCH QUESTION

Do significant correlations exist between standing posture, and hip muscle stiffness and range of motion?

METHODS

20 participants volunteered for this observational study. Passive hip stiffness was calculated as the derivative of the moment-angle curve measured during leg raising in a variety of lying postures. Stiffness was measured during hip flexion, extension, abduction and adduction. Stiffness data was obtained during the first degree and at ROM, and at the highest common angle achieved by participants in each posture Spinal curvature and other postural components were measured using a motion tracking device. Spearman rank coefficients were determined to assess any correlations between passive stiffness, range of motion, spinal curvature and other postural components.

RESULTS

Consistent relationships were found between maximum range of motion and hip stiffness at the common angles (P < 0.01), but not at maximum stiffness (P > 0.05). Consistent correlations were found between abductor stiffness and Q-angle (P < 0.05). Hip extensor range of motion correlated with lumbar lordosis (r = -0.472, P = 0.036). Other correlations were reported, but typically lacked consistency between left and right sides. Spinal curvature did not correlate with hip stiffness in frontal or sagittal planes (P > 0.05).

SIGNIFICANCE

Significant correlations were few compared with where correlations lacked statistical significance. This study demonstrates that overly simplistic assumptions about spinal posture and hip stiffness cannot be supported. Hip muscle stiffness should only be targeted in treatments where testing has demonstrated a direct need, and not assumed based upon postural assessment alone.

Measurement of Lumbar Lordosis: A Comparison of 2 Alternatives to the Cobb Angle

OBJECTIVE

The purpose of this study was to compare 2 alternative methods, the radiologic Harrison Posterior Tangent Method (HPTM) and the nonradiologic Spinal Mouse (SM), to the Cobb angle for measuring lumbar lordosis.

METHODS

Sixteen participants with previously existing lateral lumbopelvic radiographs underwent nonradiographic lordosis assessment with a Spinal Mouse. Then 2 investigators analyzed each radiograph twice using the Harrison Posterior Tangent Method and Cobb angle. Correlations were analyzed between HPTM, the Cobb angle, and SM using the Spearman rank correlation coefficient; intraexaminer and interexaminer agreement were analyzed for HPTM and the Cobb angle using intraclass correlation coefficients.

RESULTS

The HPTM correlated highly with the Cobb angle (Spearman ρ = 0.936, P < .001); SM had moderate to strong correlations with the Cobb angle (ρ = 0.737, P = .002) and HPTM (ρ = 0.707, P = .003). Intraexaminer and interexaminer agreement for the Cobb angle and HPTM were excellent (all intraclass correlation coefficients > 0.90). One participant had slight kyphosis according to HPTM and SM analyses (which consider the entire lumbar region), whereas the Cobb angle, based only on L1 and L5, reported mild lordosis for that participant.

CONCLUSION

In this sample, HPTM measurements showed high correlation with the commonly used Cobb angle, but this method requires more time and effort, and normal values have not been established. The SM may be an alternative when radiographs are inappropriate, but it measures soft tissue contours rather than lordosis itself.

Balance ability and posture in postmenopausal women with chronic pelvic pain

OBJECTIVE

The aim of the present study was to analyze balance ability and posture in postmenopausal women with chronic pelvic pain (CPP).

METHODS

This study includes a sample of 48 women with CPP recruited from the Gynecology Service of Virgen de las Nieves and San Cecilio Hospitals in Granada (Spain) and 48 healthy control women matched with respect to age and anthropometric characteristics. Outcome variables collected included: balance ability (Mini-Balance Evaluation Systems Test and Timed Up an Go Test) and posture (photogrammetry and Spinal Mouse).

RESULTS

Significant differences were found in all Mini Best Test subscales: total (P < 0.001), anticipatory (P = 0.002), reactive postural control (P < 0.001), sensory orientation (P < 0.001), and dynamic gait (P < 0.001), and all Timed Up and Go test subscales: alone (P < 0.001), with manual (P = 0.002) and cognitive task (P = 0.030). Significant differences were also found on spinal cervical angles with a forward head posture in women with CPP; global spine alignment exhibited more deviation in the women with CPP (P < 0.001); and a higher percentage of women with CPP (58%) presented with increased thoracic kyphosis and lumbar lordosis. Cohen's d was used to calculate the effect size. Some subscales of balance and posture tests showed a large effect size (d ≥0.8), indicating a more consistent result.

CONCLUSIONS

Women with CPP presented poor balance including anticipatory, reactive postural control, sensory orientation, dynamic gait, and dual task-related conditions. Posture showed higher values on the dorsal angle and lower sacral inclination, less spine alignment, and a more prevalent posture with increased kyphosis and lumbar lordosis.

The effect of a corrective functional exercise program on postural thoracic kyphosis in teenagers: a randomized controlled trial

OBJECTIVE

To investigate the effects of a corrective functional exercise program on postural thoracic kyphosis in teenagers in China.

DESIGN

A single-blind randomized controlled trial including students with a thoracic kyphosis angle (TKA) >40° measured using the SpinalMouse.

SETTING

China Institute of Sport Science and three middle schools in Beijing, China.

SUBJECTS

A total of 181 subjects were included in this trial; of these, 164 subjects were included in the analyses (intervention group, n = 81; control group, n = 83).

INTERVENTION

The intervention group received a functional exercise program designed to correct postural thoracic kyphosis, and the control group received an exercise program designed in accordance with the state-regulated curriculum.

MAIN MEASURES

The primary outcome variable was TKA. Secondary outcome variables were lumbar lordosis angle (LLA), sacral angle (SA), and incline angle (INA) measured in the upright position; thoracic, lumbar, and sacral spine range of motion (ROM) and INA ROM (change in center of gravity) measured in the forward bending and extended positions; and changes in TKA, LLA, SA, and INA measured during the Matthiass test.

RESULTS

There were significant differences in pretest and posttest TKA in both groups (intervention group: pretest 47.09 ± 5.45, posttest 38.31 ± 9.18, P < 0.0001; control group: pretest 47.47 ± 6.06, posttest 43.59 ± 7.49, P < 0.0001). After adjustment for gender and pretest values, there were significant differences in posttest TKA, change in SA, and thoracic ROM in the intervention group compared to the control group ( P < 0.05).

CONCLUSION

The corrective functional exercise program designed for this study improved exaggerated thoracic kyphosis in teenagers.

Sagittal and Frontal Plane Evaluation of the Whole Spine and Clinical Outcomes after Vertebral Fractures

Although it is known that a change in any level of the spine alters biomechanics, there are not many studies to evaluate the spine as a whole in both sagittal and frontal planes. This prospective cohort study evaluates the morphology and mobility of the entire spine in patients with vertebral fractures. The Treatment Group consisted of 43 patients who underwent percutaneous balloon kyphoplasty or percutaneous balloon kyphoplasty plus fixation. The Control Group consisted of 39 healthy subjects. Spinal Mouse was used for the assessment of the curvatures and the mobility of the spine. Clinical outcomes were evaluated by Visual Analogue Scale and Oswestry Disability Index. The measurements were recorded at 15 days and 3, 6, and 12 months postoperatively. Regarding the curvatures and mobility in sagittal plane, a statistically significant increase appeared early at 3 months, for lumbar curve, spinopelvic angulation, and overall trunk inclination. In the frontal plane, most of the improvements were recorded after 6 months. Patients with osteoporotic fracture showed statistically significant lower mean value than patients with traumatic fracture. Pain and disability index showed early improvements. This study provides a comprehensive and complete picture of the functionality of the spine in patients treated with percutaneous balloon kyphoplasty.

The effects of backward adjustable thoracic support in wheelchair on spinal curvature and back muscle activation for elderly people

OBJECTIVES

To investigate the effects of backward adjustable thoracic support on spinal curvature and back muscle activation during wheelchair sitting.

METHODS

Twenty elderly people were recruited for this study. The backward adjustable thoracic support sitting posture was compared with the slumped, normal, and lumbar support sitting postures. Spinal curvatures (pelvic, lumbar, and thoracic angles) and muscle activations of 4 back muscles on both sides (maximal voluntary isometric contraction of the lumbar multifidus, lumbar erector spinae, iliocostalis lumborum pars thoracis, and thoracic erector spinae at T9) were measured and compared between the different sitting postures using one-way analysis of variance with repeated measures.

RESULTS

The backward adjustable thoracic support sitting posture showed a relatively neutral pelvic tilt (-0.32±4.80°) when compared with the slumped (22.84±5.27°) and lumbar support (-8.97±3.31°) sitting postures (P<0.001), and showed relatively higher lumbar lordosis (-23.38±6.50°) when compared with the slumped (14.77±7.83°), normal (0.44±7.47°), and lumbar support (-16.76±4.77°) sitting postures (P<0.05). It also showed relatively lower back muscle activity when compared with the normal and lumbar support sitting postures (P<0.05).

CONCLUSIONS

The backward adjustable thoracic support sitting concept was suggested because it maintains a more neutral pelvic tilt, higher lumbar lordosis, and lower back muscle activation, which may help maintain a better sitting posture and reduce the risk of back pain.

Individual and contextual characteristics as determinants of sagittal standing posture: a population-based study of adults

BACKGROUND CONTEXT

Sagittal standing posture is associated with musculoskeletal symptoms and quality of life. However, the frequency and determinants of suboptimal sagittal alignment outside the clinical context remain to be clarified.

PURPOSE

To estimate the association of sociodemographic, anthropometric, and behavioral characteristics with sagittal standing posture among adults from the general population.

STUDY DESIGN

Cross-sectional evaluation of a population-based sample.

PATIENT SAMPLE

As part of the EPIPorto study, 489 adults were assessed during 2005 to 2008.

OUTCOME MEASURES

Individual spinopelvic parameters were measured. Additionally, participants were classified into one of four types of sagittal postural patterns (Roussouly classification: Types 1, 2, and 4 corresponding to nonneutral postures and Type 3 to a neutral posture).

METHODS

Spinopelvic parameters were recorded from 36-inch sagittal radiographs obtained in free-standing posture. Age, sex, education, occupation, body mass index (BMI), waist circumference, total physical activity, leisure time physical activity, time spent in sitting position, smoking status, and tobacco cumulative exposure were collected. Individual parameters and patterns of sagittal posture were compared across categories of participants' characteristics.

RESULTS

Older age, lower educational level, blue collar occupation, and overall and central obesity were associated with increased sagittal vertical axis and pelvic tilt/pelvic incidence ratio. Taking the neutral postural pattern (Type 3) as reference for the outcome in a multinomial regression model, independently of age, sex, education, total physical activity, and smoking status, overweight adults had higher odds of Type 2 (odds ratio [OR]=1.92; 95% confidence interval [CI]: 1.13-3.27) and Type 4 (OR=2.13; 95% CI: 1.16-3.91) postural patterns in comparison with normal weight subjects. Overall and central obesity were positively related with Type 1 postural pattern (OR=6.10, 95% CI: 1.52-24.57 and OR=3.54, 95% CI: 1.13-11.11, respectively). There was also a weak direct association between female sex and Type 1 postural pattern. Regarding behavioral factors, subjects with total physical activity above the first third exhibited all nonneutral postural patterns less frequently, and current smokers were more likely to present a Type 4 postural pattern.

CONCLUSIONS

Higher BMI and central obesity were important potential determinants of nonneutral posture among adults from the general population. Future research should investigate the potential effectiveness of overweight prevention and management in avoiding sagittal misalignment conditions.

Agreement between fiber optic and optoelectronic systems for quantifying sagittal plane spinal curvature in sitting

Spinal posture affects how individuals function from a manual wheelchair. There is a need to directly quantify spinal posture in this population to ultimately improve function. A fiber optic system, comprised of an attached series of sensors, is promising for measuring large regions of the spine in individuals sitting in a wheelchair. The purpose of this study was to determine the agreement between fiber optic and optoelectronic systems for measuring spinal curvature, and describe the range of sagittal plane spinal curvatures in natural sitting. Able-bodied adults (n = 26, 13 male) participated. Each participant assumed three sitting postures: natural, slouched (accentuated kyphosis), and extension (accentuated lordosis) sitting. Fiber optic (ShapeTape) and optoelectronic (Optotrak) systems were applied to the skin over spinous processes from S1 to C7 and used to measure sagittal plane spinal curvature. Regions of kyphosis and lordosis were identified. A Cobb angle-like method was used to quantify lordosis and kyphosis. Generalized linear model and Bland-Altman analyses were used to assess agreement. A strong correlation exists between curvature values obtained with Optotrak and ShapeTape (R(2) = 0.98). The mean difference between Optotrak and ShapeTape for kyphosis in natural, extension, and slouched postures was 4.30° (95% LOA: -3.43 to 12.04°), 3.64° (95% LOA: -1.07 to 8.36°), and 4.02° (95% LOA: -2.80 to 10.84°), respectively. The mean difference for lordosis, when present, in natural and extension postures was 2.86° (95% LOA: -1.18 to 6.90°) and 2.55° (95% LOA: -3.38 to 8.48°), respectively. In natural sitting, the mean ± SD of kyphosis values was 35.07 ± 6.75°. Lordosis was detected in 8/26 participants: 11.72 ± 7.32°. The fiber optic and optoelectronic systems demonstrate acceptable agreement for measuring sagittal plane thoracolumbar spinal curvature.

Sagittal standing posture, back pain, and quality of life among adults from the general population: a sex-specific association

STUDY DESIGN

A prospective radiographical study of sagittal standing posture among adults consecutively recruited from the general population.

OBJECTIVE

To analyze the relation of suboptimal sagittal standing posture with back pain and health-related quality of life in general adult males and females.

SUMMARY OF BACKGROUND DATA

Clinical studies have shown the association of sagittal standing posture with pain and reduced quality of life, but this relation has not been assessed in the general adult population.

METHODS

As part of the EPIPorto population-based study of adults, 178 males and 311 females were evaluated. Age, education, and body mass index were recorded. Radiographical data collection consisted of 36-in. standing sagittal radiographs. Creation of 3 groups for individual spinopelvic parameters was performed (low, intermediate, or high), and 1 of 4 sagittal types of postural patterns attributed to each participant (Roussouly classification). Back pain prevalence and severity were assessed on the basis of self-reported data and health-related quality of life using 2 main components of the 36-Item Short Form Health Survey.

RESULTS

In males, differences in back pain severity were observed only among pelvic tilt/pelvic incidence ratio groups. Females presenting high pelvic incidence and sacral slope exhibited higher odds of severe back pain than those with intermediate values (adjusted odds ratios = 2.21 and 2.15; 95% confidence interval, 1.24-3.97 and 1.21-3.86; respectively). Sagittal vertical axis showed the largest differences in physical quality of life of females: high group had 8.8 lower score than the low group (P < 0.001), but this result lost statistical significance after adjustment for age, education, and body mass index.

CONCLUSION

Sagittal standing posture was not consistently associated with quality of life measures in males. Increased pelvic incidence and sacral slope may be involved in causing severe back pain among females. Monitoring sagittal postural parameters has limited usefulness as a screening tool for causes of unspecific musculoskeletal symptoms in the general adult population.

LEVEL OF EVIDENCE

3.

Is the sagittal postural alignment different in normal and dysphonic adult speakers?

OBJECTIVE

Clinical research in the field of voice disorders, in particular functional dysphonia, has suggested abnormal laryngeal posture due to muscle adaptive changes, although specific evidence regarding body posture has been lacking. The aim of our study was to verify if there were significant differences in sagittal spine alignment between normal (41 subjects) and dysphonic speakers (33 subjects).

STUDY DESIGN

Cross-sectional study.

METHODS

Seventy-four adults, 35 males and 39 females, were submitted to sagittal plane photographs so that spine alignment could be analyzed through the Digimizer-MedCalc Software Ltd program. Perceptual and acoustic evaluation and nasoendoscopy were used for dysphonic judgments: normal and dysphonic speakers.

RESULTS

For thoracic length curvature (TL) and for the kyphosis index (KI), a significant effect of dysphonia was observed with mean TL and KI significantly higher for the dysphonic speakers than for the normal speakers. Concerning the TL variable, a significant effect of sex was found, in which the mean of the TL was higher for males than females. The interaction between dysphonia and sex did not have a significant effect on TL and KI variables. For the lumbar length curvature variable, a significant main effect of sex was demonstrated; there was no significant main effect of dysphonia or significant sex×dysphonia interaction.

CONCLUSIONS

Findings indicated significant differences in some sagittal spine posture measures between normal and dysphonic speakers. Postural measures can add useful information to voice assessment protocols and should be taken into account when considering particular treatment strategies.

The use of posterior vertebral column resection in the management of severe posttuberculous kyphosis: a retrospective study and literature review

PURPOSE

We present a retrospective study of 15 cases with severe posttuberculous kyphosis of thoracolumbar region that underwent posterior vertebral column resection.

METHODS

From 2004 to 2009, 15 consecutive patients with posttubercular kyphotic deformity underwent posterior vertebral resection osteotomy. Six subjects were females and nine were males with an average age of 35.8 years (range 20-60 years) at the time of surgery. None of the patients had neurological deficits. The mean preoperative visual analogue scale was 8.7 (range 3-9), and the average preoperative Oswestry Disability Index was 46.5 (range 40-56).

RESULTS

The average duration of postoperative follow-up was 36.1 ± 10.7 months (range 24-62 months). The number of vertebra resected was 1.3 (range 1-2) on average. There were ten patients with one-level osteotomy and five patients with two-level osteotomy. The average operation time was 446.0 ± 92.5 min (range 300-640 min) with an average blood loss of 1,653.3 ± 777.9 ml (range 800-3000 ml). The focal kyphosis before surgery averaged 92.3 ± 8.9° (range 74-105°), and the kyphotic angle decreased to 34.5 ± 8.7° on average after the surgical correction. The average kyphotic angle at the last follow-up was 36.9 ± 8.5°, loss of correction was 2.4 ± 1.4° on average. All patients postoperatively received bony fusion within 6-9 months.

CONCLUSIONS

Our results showed that although posterior vertebral resection is a highly technical procedure, it can be used safely and effectively in the management of severe posttuberculous kyphosis. It is imperative that operations be performed by an experienced surgical team to prevent operation-related complications.

Influence of sagittal balance on spinal lumbar loads: a numerical approach

BACKGROUND

Pathological deformities involving the sagittal alignment of the spine may lead to loss of spine stability and imbalance. The effect of different patterns of sagittal balance on the loads acting in the spine was only marginally investigated, although it would be of critical importance in the clinical management of spinal disorders.

METHODS

Optimization-based finite element models of the human spine in the standing position able to predict the loads acting in the lumbar spine and the activation of the spinal muscles were developed and used to explore a wide range of sagittal balance conditions, covering both inter-subject variability and pathological imbalance. 1000 two-dimensional randomized spine models with simplified geometry were generated by varying anatomical parameters such as lumbar lordosis, sacral slope, and C7 plumb line. Muscular loads were calculated by means of an optimization procedure aimed to minimize total muscular stress.

FINDINGS

The simulation of a physiological spine in the standing position predicted average disk stresses ranging from 0.38 to 0.5MPa, in good agreement with in vivo measurements. The C7 plumb line and the parameters describing the lumbar spine were found to be the strongest determinants of the lumbar loads and muscle activity. Marginal relevance was found concerning the thoracic and cervical parameters.

INTERPRETATION

The present modeling approach was found to be able to capture correlations between sagittal parameters and the loads acting in the lumbar spine. The method represents a good platform for future improvements aimed at patient-specific modeling to support pre-operative surgical planning.

Anterior and posterior variations in mechanical properties of human vertebrae measured by nanoindentation

Osteoporotic spinal fractures are a significant global public health issue affecting more than 200 million people. Local degradation of the mechanical properties of bone and changes in global spine curvature increase fracture risk. However, a gap in knowledge exists relating material properties of trabecular bone in different regions of the spine. The purpose of our project was to measure the intrinsic mechanical properties of the anterior and posterior regions of human vertebral bodies in the thoracic and lumbar spine. Nanoindentation was used to evaluate Young's modulus (E) and hardness (H) of anterior and posterior trabecular bone regions from each vertebra (T7, T8 and L4). One-way ANOVA and the Turkey-Kramer test were used to analyze significance between vertebrae and t-test was used to test for significance within vertebrae. There was no difference in (E) and (H) within vertebrae. Young's modulus in the anterior regions of T7 (19.8±1.3) and T8 (19.6±1.4) were statistically greater than that in L4 (17.6±0.5). There was no difference between the posterior regions of all the vertebrae. There was a statistical significant difference in hardness between the anterior regions of T7 and T8 compared to L4, while the posterior regions demonstrated no difference. The results presented in this study, for the first time, reveal the differences in bone properties between the kyphotic thoracic spine and lordotic lumbar spine regions. This information will be helpful in understanding vertebral body remodeling and adaption in different regions of the spine which may be associated with spinal curvature and loading conditions.

Longitudinal changes in lumbar bone mineral density distribution may increase the risk of wedge fractures

BACKGROUND

Trabecular bone strength diminishes as a result of osteoporosis and altered biomechanical loading at the vertebral and spinal levels. The spine consists of the anterior, middle and posterior columns and the load supported by the anterior and middle columns will differ across different regions of the spine. Stress shielding of the anterior column can contribute to bone loss and increase the risk of wedge fracture. There is a lack of quantitative data related to regional spinal bone mineral density distribution over time. We hypothesize that there is an increase in the posterior-to-anterior vertebral body bone mineral density ratio and a decrease in whole-body bone mineral density over time.

METHODS

Bone mineral density was measured in 33 subjects using quantitative computed tomography scans for L1-L3 vertebrae, region (anterior and posterior vertebral body), and time (baseline and 6 years after).

FINDINGS

Lumbar bone mineral density decreased significantly (Δ: ~15%) from baseline to the 6th year visit. Individual vertebra differences over time (L1: ~14%, L2: ~14%, L3: ~17%) showed statistical significance. Anterior bone mineral density change was significantly greater than in the posterior vertebral body region (Δ anterior: ~18%; Δ posterior: ~13%). Posterior-to-anterior bone mineral density ratio was significantly greater in the 6th year compared to baseline values (mean (SD), 1.33 (0.2) vs. 1.23 (0.1)).

INTERPRETATION

This study provides longitudinal quantitative measurement of bone mineral density in vertebrae as well as regional changes in the anterior and posterior regions. Understanding bone mineral density distribution over time may help to decrease the risk of wedge fractures if interventions can be developed to bring spine loading to its normal state.