Comparison of pelvic incidence measurement using lateral x-ray, standard ct versus ct with 3d reconstruction

PURPOSE

Pelvic incidence (PI) is a position independent parameter used to quantify spinopelvic sagittal balance. PI is generally measured on lateral radiographs, but more recent studies have suggested better accuracy with standard CT scans versus three-dimensional (3D) CT scans. This study compares PI obtained from lateral XR, standard CT scan and CT scan with 3D reconstruction.

METHODS

A total of 77 subjects with lateral XRs of the pelvis or lumbosacral spine and CT scans of the pelvis were randomly selected. Pelvic incidence on lateral XRs, standard CT scans and CT scans utilizing multiplanar reconstruction were measured and compared using intraclass correlation coefficients (ICC). PI was also measured on serial images in 28 individuals using the same imaging modality within 3 years and evaluated using ICC.

RESULTS

Mean ± SD of PI measurements on XR, standard CT and CT with 3D reconstruction were 56° ± 13°, 53° ± 12° and 53° ± 12°, respectively, demonstrating a small but significant elevation of PI measurement on XR (P < 0.001). ICC values demonstrated a higher correlation between standard CT and 3D CT (ICC 0.986), compared to XR and standard CT (ICC 0.934) and XR and 3D CT (ICC 0.937). PI measurements on repeated imaging of the same individual also demonstrated that both CT methods produced more consistent measurements (ICC 0.986 for standard CT, 0.981 for 3D CT, 0.935 for XR).

CONCLUSION

Although standard XR does provide a high level of reliability, it appears to slightly overestimate PI. CT scans do provide increased reliability, with no additional benefit of 3D reconstructions over standard CT.

Spinopelvic Compensatory Mechanisms for Reduced Hip Motion (ROM) in the Setting of Hip Osteoarthritis

STUDY DESIGN

Retrospective review from a single institution.

OBJECTIVE

To investigate the effect of hip osteoarthritis (OA) on spinopelvic compensatory mechanisms as a result of reduced hip range of motion (ROM) between sitting and standing.

SUMMARY OF BACKGROUND DATA

Hip OA results in reduced hip ROM and contracture, causing pain during postural changes. Hip flexion contracture is known to reduce the ability to compensate for spinal deformity while standing; however, the effects of postural spinal alignment change between sitting and standing is not well understood.

METHODS

Sit-stand radiographs of patients without prior spinal fusion or hip prosthesis were evaluated. Hip OA was graded by Kellgren-Lawrence grades and divided into low-grade (LOA; grade 0-2) and severe (SOA; grade 3 or 4) groups. Radiographic parameters evaluated were pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, thoracic kyphosis (TK), SVA, T1-pelvic angle (TPA), T10-L2, proximal femoral shaft angle (PFSA), and hip flexion (PT change-PFSA change). Changes in sit-stand parameters were compared between LOA and SOA groups.

RESULTS

548 patients were included (LOA = 311; SOA = 237). After propensity score matching for age, body mass index, and PI, 183 LOA and 183 SOA patients were analyzed. Standing analysis demonstrated that SOA had higher SVA (31.1 vs. 21.7), lower TK (-36.2 vs. -41.1), and larger PFSA (9.1 vs. 7.4) (all p < .05). Sitting analysis demonstrated that SOA had higher PT (29.7 vs. 23.3), higher PI-LL (21.6 vs. 12.4), less LL (31.7 vs. 41.6), less TK (-33.2 vs. -38.6), and greater TPA (27.9 vs. 22.5) (all p < .05). SOA had less hip ROM from standing to sitting versus LOA (71.5 vs. 81.6) (p < .05). Therefore, SOA had more change in PT (15.2 vs. 7.3), PI-LL (20.6 vs. 13.7), LL (-21.4 vs. -13.1), and T10-L2 (-4.9 vs. -1.1) (all p < .001), allowing the femurs to change position despite reduced hip ROM. SOA had greater TPA reduction (15.1 vs. 9.6) and less PFSA change (86.7 vs. 88.8) compared with LOA (both p < .001).

CONCLUSIONS

Spinopelvic compensatory mechanisms are adapted for reduced hip joint motion associated with hip OA in standing and sitting.

LEVEL OF EVIDENCE

Level III.

Evaluation of anatomical pelvic parameters between normal, healthy men and women using three-dimensional computed tomography: a cross-sectional study of sex-specific and age-specific differences

Background

Sagittal spinal balance and standing posture are affected by pelvic morphology, especially pelvic incidence (PI). However, it is not difficult to identify the hip center because of overlap of the pelvis, image contrast, and soft tissue artifacts. Measurements of PI are not always suitable in all patients, especially those with osteoarthritis of the hip joint whose femoral head is nonspherical, subluxed, or dislocated. We measured PI, pelvic tilt (PT), and sacral slope (SS) as anatomical parameters using a novel three-dimensional measurement in order to compare the pelvic morphology between normal, healthy men and women.

Methods

In this cross-sectional study, we evaluated 108 Japanese subjects (55 men, 53 women) without low back or knee pain. We used the three-dimensional pelvis model adjusted to the anterior pelvic plane and measured the pelvic parameters. The subjects were stratified by age (< 50 versus ≥ 50 years) and sex. Intraobserver and interobserver reliabilities were calculated with intraclass correlation coefficients.

Results

There was no significant difference in PI, anatomical-PT, and anatomical-SS between sexes. There was a strong correlation between PI and anatomical-SS in men and women (R = 0.790 and 0.715, respectively). Values of anatomical-PT were lower, and values of anatomical-SS were greater among older subjects than among younger subjects; the value of PI was similar between younger and older subjects. Intraobserver and interobserver mean absolute differences were about 2 mm and 2°, respectively; the intraclass correlation coefficient was > 0.87.

Conclusions

We found a strong correlation between PI and anatomical-SS in men and women. This novel measurement concept may be useful to estimate PI from anatomical-SS because the measurements of PI are not always suitable in all patients, especially those with osteoarthritis of the hip joint whose femoral head is not spherical or whose femoral head is subluxed or dislocated. This is the first report to describe the relationship between PI, anatomical-PT, and anatomical-SS as morphologic parameters with a high interclass correlation coefficient for intraobserver and interobserver reliabilities.

How does the sagittal spinal balance of the scoliotic population deviate from the asymptomatic population?

Background

Previously, the sagittal spinal balance in both asymptomatic and scoliotic Caucasian people has been characterized and compared. Very recently, the sagittal spino-pelvic parameters among asymptomatic Chinese adults have been studied, and the results were compared with Caucasian adults, indicating that a difference did exist. Unfortunately, the distribution of sagittal standing posture patterns among the Chinese population has not been characterized in either asymptomatic or scoliotic groups.

Methods

We conducted a radiographic comparison study to define the deviation of sagittal balance in scoliotic patients from that of an asymptomatic population. A total of 126 asymptomatic and 117 idiopathic scoliotic (IS) young adults were recruited. Radiographic data from each subject were reviewed, and sagittal spinopelvic parameters were measured. The Roussouly type was then determined, as well as the relative position of the C7 plumbline with respect to the sacrum and hip axis. Comparison analyses were undertaken between the two different groups.

Results

The IS group had a larger pelvic incidence, pelvic tilt and sacral slope, but a smaller spinal tilt than the asymptomatic group (P < 0.05), while other sagittal parameters were similar. The distribution of Roussouly types was similar between the asymptomatic and IS groups, of which 49.2% and 45.3% belonged to Roussouly Type 3, respectively. Asymptomatic males and females had a similar distribution, which was different between the two genders in the IS group (P < 0.05), with more females possessing a neutral sagittal standing posture. In addition, more IS subjects had forward displacement of the C7 plumbline than asymptomatic ones (P < 0.05), while there was no difference between the two genders in either group.

Conclusions

Although sagittal pelvic parameters were greater in the IS population, their sagittal spinal balance was maintained and there was no sagittal standing posture pattern correlated with IS. The occurrence of anterior displacement of the C7 plumbline was more common in IS patients than asymptomatic adults, but did not appear to be correlated with gender in both populations.

Correlates of bone mineral density and sagittal spinal balance in the aged

Objective

To investigate the relationship between bone mineral density (BMD) and sagittal spinal balance in the Korean elderly population.

Methods

The retrospective study included subjects aged 60 years and above, who had whole-spine lateral radiography and dual-energy X-ray absorptiometry (DEXA) within a year's gap between each other. Sagittal vertical axis (SVA) for evaluation of sagittal spinal balance and five spinopelvic parameters were measured through radiography. The presence of compression fracture was identified. Correlations of BMD T-scores with SVA and with the spinopelvic parameters were assessed using Pearson correlation coefficient (PCC). Linear regression analyses were performed between SVA and the clinical and radiologic variables.

Results

One hundred twenty-two subjects (42 males and 80 females; mean age, 69.93±5.5 years) were included in the study. BMD, femur or spine, was not correlated with SVA or any spinopelvic parameters in both genders (PCC<±0.2), except that spine BMD in men was associated with sacral slope. Univariate regression analysis revealed association between SVA and lumbar lordosis, pelvic tilt, and compression fractures in both genders; it was also associated with age and pelvic incidence in females and with sacral slope in males. Multivariate linear regression model showed lumbar lordosis and compression fracture as variables affecting SVA in both sexes; pelvic incidence was another factor affecting SVA in women only.

Conclusion

BMD was not associated with sagittal spinal balance in the aged. Sagittal spinal balance was explained partly by lumbar lordosis and compression fracture. Further study is warranted to understand progression of sagittal imbalance with age.

Analysis of sagittal spinopelvic parameters in cerebral palsy

BACKGROUND CONTEXT

Knowledge of sagittal spinopelvic parameters is important for the treatment of cerebral palsy (CP) because they differ in the normal population and can induce symptoms.

PURPOSE

To analyze the sagittal spinal alignment and the pelvic orientation in CP.

STUDY DESIGN

Radiological analysis of patients with CP.

METHODS

The study and control groups comprised 57 CP patients and 24 healthy volunteers, respectively. All the patients underwent lateral radiography of the whole spine including hip joints. The radiographic parameters examined were sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), S1 overhang (OH), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL1 and 2), and sagittal balance (SB). Statistical analysis was performed to identify the significant differences between the two study groups. In addition, correlations were sought between the parameters and symptoms.

RESULTS

The PT and OH were significantly smaller in the CP patients, whereas SS, TLK, LL1, LL2, and SB were significantly greater (p<.05). Correlation analysis revealed significant relationships between the sagittal parameters. Specifically, PI was found to be associated with SS, PT, and OH, whereas the spinal parameters LL1 and LL2 were found to be related to TK and SB. Between spine and pelvic parameters, LL1 and LL2 were found to be related to SS, PT, PI, and OH and in addition, SB was found to be related to TLK, LL1, and LL2. An analysis of relations between the symptoms and parameters revealed a positive correlation between the severities of symptoms and PT, OH, and TLK (r=0.300, p=.023; r=0.306, p=.020; r=0.289, p=.029, respectively).

CONCLUSIONS

A significant difference was observed in the sagittal spinopelvic parameters in the CP and normal control groups and was possibly related to the symptoms. The study shows that the evaluations of sagittal spinopelvic parameters could be useful during the treatment of disorders associated with CP.