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Increased pelvic incidence may lead to arthritis and sagittal orientation of the facet joints at the lower lumbar spine.

Jentzsch T, Geiger J, Bouaicha S, Slankamenac K, Nguyen-Kim TD, Werner CM - BMC Med Imaging (2013)

Bottom Line: PI was significantly and linearly correlated with (4) LL (p = < 0.0001).An increased PI was also significantly associated with more sagitally oriented FJs at L5/S1 (p = 0.01).Once symptomatic or in the event of spinal trauma, patients with increased PI and LL could benefit from corrective surgery and spondylodesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Trauma Surgery, Department of Surgery, University Hospital Zuerich, Zuerich, Switzerland. thorsten.jentzsch@usz.ch.

ABSTRACT

Background: Correct sagittal alignment with a balanced pelvis and spine is crucial in the management of spinal disorders. The pelvic incidence (PI) describes the sagittal pelvic alignment and is position-independent. It has barely been investigated on CT scans. Furthermore, no studies have focused on the association between PI and facet joint (FJ) arthritis and orientation. Therefore, our goal was to clarify the remaining issues about PI in regard to (1) physiologic values, (2) age, (3) gender, (4) lumbar lordosis (LL) and (5) FJ arthritis and orientation using CT scans.

Methods: We retrospectively analyzed CT scans of 620 individuals, with a mean age of 43 years, who presented to our traumatology department and underwent a whole body CT scan, between 2008 and 2010. The PI was determined on sagittal CT planes of the pelvis by measuring the angle between the hip axis to an orthogonal line originating at the center of the superior end plate axis of the first sacral vertebra. We also evaluated LL, FJ arthritis and orientation of the lumbar spine.

Results: 596 individuals yielded results for (1) PI with a mean of 50.8°. There was no significant difference for PI and (2) age, nor (3) gender. PI was significantly and linearly correlated with (4) LL (p = < 0.0001). Interestingly, PI and (5) FJ arthritis displayed a significant and linear correlation (p = 0.0062) with a cut-off point at 50°. An increased PI was also significantly associated with more sagitally oriented FJs at L5/S1 (p = 0.01).

Conclusion: PI is not correlated with age nor gender. However, this is the first report showing that PI is significantly and linearly associated with LL, FJ arthritis and more sagittal FJ orientation at the lower lumbar spine. This may be caused by a higher contact force on the lower lumbar FJs by an increased PI. Once symptomatic or in the event of spinal trauma, patients with increased PI and LL could benefit from corrective surgery and spondylodesis.

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Related in: MedlinePlus

Facet Joints (FJs): FJ orientation was evaluated by measuring the angle between the midline of the sagittal plane and the midline of the FJ as described by Schuller and Mahato [[49],[50]]. Coronal FJ orientation is shown on the left side, whereas sagittal orientation including measurement of FJ orientation is shown on the right side. The red box indicates the PI. The blacked out numbers were disregarded because they were created automatically by our software and contained irrelevant information.
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Figure 3: Facet Joints (FJs): FJ orientation was evaluated by measuring the angle between the midline of the sagittal plane and the midline of the FJ as described by Schuller and Mahato [[49],[50]]. Coronal FJ orientation is shown on the left side, whereas sagittal orientation including measurement of FJ orientation is shown on the right side. The red box indicates the PI. The blacked out numbers were disregarded because they were created automatically by our software and contained irrelevant information.

Mentions: (1) The PI was determined on sagittal CT planes of the pelvis using the AGFA® Impax viewer by measuring the angle between the hip axis to an orthogonal line originating at the center of the superior end plate axis of the first sacral vertebra [8] (Figure 1). Precisely, this was done in the following manner: Firstly, a line was drawn along the axis of the superior end plate of S1. Then, an orthogonal line originating at the center of this axis was drawn. Secondly, the middle of the femoral head was determined by the intersecting point of a vertical and horizontal line within the femoral head. Finally, a line was drawn from the middle of the each femoral head to the center of the superior end plate axis and the angle was measured in regard to the orthogonal line originating at this point, In order to acquire the superposition of the two femoral heads, left and right, the PI was measured for both sides and the mean was stated. (2) Individuals were grouped into different age groups according to low, i.e. 40 years, and high, i.e. 70 years, cut-off points chosen by Kalichman et al. [43] as well as the assumption of different activity levels and degenerative processes in younger individuals ≤ 30 years, middle-aged individuals between 31–50 years and aging individuals between 51–70 years. The first group included individuals ≤ 40 and ≥ 41 years and the second group included individuals ≤ 30 years, 31–50 years, 51–70 years and ≥ 71 years. (3) Gender was also evaluated. (4) LL was evaluated on the middle of the sagittal planeby measuring the angle between the superior endplates of L1 and S1, based on the definition of Stokes and the Scoliosis Research Society [27,44] (Figure 2). The middle of the sagittal plane could be easily determined in Agfa® Impax viewer by a coexisting alignment line at the axial plane that can be viewed on the frame right next to the sagittal plane. (5) FJs of the lumbar spine were evaluated between the second lumbar and the first sacral level [45] (Figure 3). Axial planes with the largest intersecting set of the superior and inferior FJ process were chosen. Assessment of FJ arthritis was carried out as previously described in similar studies, where a grading scale described by Pathria was used [46,47]. Grade 0 (normal) indicates a normal facet joint, whereas grades 1 – 3 display increasing signs of FJ arthritis with each grade including signs of the lower grade. Grade 1 (mild) shows joint space narrowing, grade 2 (moderate) demonstrates sclerosis and grade 3 (severe) reveals osteophytes [48]. FJ orientation in the axial plane was evaluated by measuring the angle between the midline of the sagittal plane and the midline of the FJ as described by Schuller and Mahato [49,50]. The midline of the sagittal planes corresponds to a line drawn through the center of the vertebral body and spinous process. Therefore, each FJ was compared against this line. The overall FJ orientation was calculated by averaging the angles between the right and left side of the FJs. We used absolute angles, indicating that we did not consider rotation in one direction as positive nor rotation in the opposite direction as negative. The FJ orientation was labeled as coronal if angles were > 45° and sagittal if angles were ≤ 45° [51].


Increased pelvic incidence may lead to arthritis and sagittal orientation of the facet joints at the lower lumbar spine.

Jentzsch T, Geiger J, Bouaicha S, Slankamenac K, Nguyen-Kim TD, Werner CM - BMC Med Imaging (2013)

Facet Joints (FJs): FJ orientation was evaluated by measuring the angle between the midline of the sagittal plane and the midline of the FJ as described by Schuller and Mahato [[49],[50]]. Coronal FJ orientation is shown on the left side, whereas sagittal orientation including measurement of FJ orientation is shown on the right side. The red box indicates the PI. The blacked out numbers were disregarded because they were created automatically by our software and contained irrelevant information.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4228336&req=5

Figure 3: Facet Joints (FJs): FJ orientation was evaluated by measuring the angle between the midline of the sagittal plane and the midline of the FJ as described by Schuller and Mahato [[49],[50]]. Coronal FJ orientation is shown on the left side, whereas sagittal orientation including measurement of FJ orientation is shown on the right side. The red box indicates the PI. The blacked out numbers were disregarded because they were created automatically by our software and contained irrelevant information.
Mentions: (1) The PI was determined on sagittal CT planes of the pelvis using the AGFA® Impax viewer by measuring the angle between the hip axis to an orthogonal line originating at the center of the superior end plate axis of the first sacral vertebra [8] (Figure 1). Precisely, this was done in the following manner: Firstly, a line was drawn along the axis of the superior end plate of S1. Then, an orthogonal line originating at the center of this axis was drawn. Secondly, the middle of the femoral head was determined by the intersecting point of a vertical and horizontal line within the femoral head. Finally, a line was drawn from the middle of the each femoral head to the center of the superior end plate axis and the angle was measured in regard to the orthogonal line originating at this point, In order to acquire the superposition of the two femoral heads, left and right, the PI was measured for both sides and the mean was stated. (2) Individuals were grouped into different age groups according to low, i.e. 40 years, and high, i.e. 70 years, cut-off points chosen by Kalichman et al. [43] as well as the assumption of different activity levels and degenerative processes in younger individuals ≤ 30 years, middle-aged individuals between 31–50 years and aging individuals between 51–70 years. The first group included individuals ≤ 40 and ≥ 41 years and the second group included individuals ≤ 30 years, 31–50 years, 51–70 years and ≥ 71 years. (3) Gender was also evaluated. (4) LL was evaluated on the middle of the sagittal planeby measuring the angle between the superior endplates of L1 and S1, based on the definition of Stokes and the Scoliosis Research Society [27,44] (Figure 2). The middle of the sagittal plane could be easily determined in Agfa® Impax viewer by a coexisting alignment line at the axial plane that can be viewed on the frame right next to the sagittal plane. (5) FJs of the lumbar spine were evaluated between the second lumbar and the first sacral level [45] (Figure 3). Axial planes with the largest intersecting set of the superior and inferior FJ process were chosen. Assessment of FJ arthritis was carried out as previously described in similar studies, where a grading scale described by Pathria was used [46,47]. Grade 0 (normal) indicates a normal facet joint, whereas grades 1 – 3 display increasing signs of FJ arthritis with each grade including signs of the lower grade. Grade 1 (mild) shows joint space narrowing, grade 2 (moderate) demonstrates sclerosis and grade 3 (severe) reveals osteophytes [48]. FJ orientation in the axial plane was evaluated by measuring the angle between the midline of the sagittal plane and the midline of the FJ as described by Schuller and Mahato [49,50]. The midline of the sagittal planes corresponds to a line drawn through the center of the vertebral body and spinous process. Therefore, each FJ was compared against this line. The overall FJ orientation was calculated by averaging the angles between the right and left side of the FJs. We used absolute angles, indicating that we did not consider rotation in one direction as positive nor rotation in the opposite direction as negative. The FJ orientation was labeled as coronal if angles were > 45° and sagittal if angles were ≤ 45° [51].

Bottom Line: PI was significantly and linearly correlated with (4) LL (p = < 0.0001).An increased PI was also significantly associated with more sagitally oriented FJs at L5/S1 (p = 0.01).Once symptomatic or in the event of spinal trauma, patients with increased PI and LL could benefit from corrective surgery and spondylodesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Trauma Surgery, Department of Surgery, University Hospital Zuerich, Zuerich, Switzerland. thorsten.jentzsch@usz.ch.

ABSTRACT

Background: Correct sagittal alignment with a balanced pelvis and spine is crucial in the management of spinal disorders. The pelvic incidence (PI) describes the sagittal pelvic alignment and is position-independent. It has barely been investigated on CT scans. Furthermore, no studies have focused on the association between PI and facet joint (FJ) arthritis and orientation. Therefore, our goal was to clarify the remaining issues about PI in regard to (1) physiologic values, (2) age, (3) gender, (4) lumbar lordosis (LL) and (5) FJ arthritis and orientation using CT scans.

Methods: We retrospectively analyzed CT scans of 620 individuals, with a mean age of 43 years, who presented to our traumatology department and underwent a whole body CT scan, between 2008 and 2010. The PI was determined on sagittal CT planes of the pelvis by measuring the angle between the hip axis to an orthogonal line originating at the center of the superior end plate axis of the first sacral vertebra. We also evaluated LL, FJ arthritis and orientation of the lumbar spine.

Results: 596 individuals yielded results for (1) PI with a mean of 50.8°. There was no significant difference for PI and (2) age, nor (3) gender. PI was significantly and linearly correlated with (4) LL (p = < 0.0001). Interestingly, PI and (5) FJ arthritis displayed a significant and linear correlation (p = 0.0062) with a cut-off point at 50°. An increased PI was also significantly associated with more sagitally oriented FJs at L5/S1 (p = 0.01).

Conclusion: PI is not correlated with age nor gender. However, this is the first report showing that PI is significantly and linearly associated with LL, FJ arthritis and more sagittal FJ orientation at the lower lumbar spine. This may be caused by a higher contact force on the lower lumbar FJs by an increased PI. Once symptomatic or in the event of spinal trauma, patients with increased PI and LL could benefit from corrective surgery and spondylodesis.

Show MeSH
Related in: MedlinePlus