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

Correlation between the sacral tilt measured with an inclinometer and the pelvic tilt as a tool for assessing the pelvic position

[Purpose] The aim of this study was to examine whether the forward tilt of the sacrum, which can be measured using an inclinometer, correlates with pelvic tilt and is therefore suitable for therapeutic use as part of a postural assessment for treatment planning or for preventive screening. [Participants and Methods] In 121 athletes (22 females, 99 males), we measured the forward tilt of the sacrum in habitual stance using a digital inclinometer attached to the skin at the level of the posterior superior spinae. At the same time, the forward tilt of the pelvis was determined using videography. For this purpose, we determined the angle between two marker spheres placed on the posterior and anterior superior spinae and the horizontal using sagittal posture photographs. [Results] Taking age as a control variable, we found a significant correlation of moderate strength between pelvic tilt and sacral tilt in men. In women, there was a significant correlation with a strong effect. [Conclusion] The measurement of sacral tilt using an inclinometer positioned on the skin between the posterior superior spinae correlates statistically significantly with pelvic tilt and is therefore suitable as an easy-to-use diagnostic tool for therapeutic use in treatment planning and evaluation.

Randomized Trial of Augmented Pelvic Fixation in Patients Undergoing Thoracolumbar Fusion for Adult Spine Deformity: Initial Results from a Multicenter Randomized Trial

BACKGROUND

The optimal configuration for spinopelvic fixation during multilevel spine fusion surgery for adult spine deformity remains unclear. Postoperative sacroiliac (SI) joint pain, S2AI screw loosening and implant breakage could be related to continued motion of the SI joint with use of only a single point of fixation across the SI joint.

METHODS

Prospective, international, multicenter randomized controlled trial of 222 patients with adult spine deformity scheduled for multilevel (4 or more levels) spine fusion surgery with pelvic fixation. Subjects were randomized to sacroalar (S2) iliac (S2AI) screws alone for pelvic fixation or S2AI + triangular titanium implants placed cephalad to S2AI screws. Quad rod techniques were not allowed or used. Baseline spinal deformity measures were read by an independent radiologist. Site-reported perioperative adverse events were reviewed by a clinical events committee. Quality of life questionnaires and other clinical outcomes are in process with planned 2-year follow-up.

RESULTS

One hundred thirteen participants were assigned to S2AI and 109 to S2AI + titanium triangular implants (TTI). 35/222 (16%) of all subjects had a history of SI joint pain or were diagnosed with SI joint pain during preoperative workup. Three-month follow-up was available in all but 4 subjects. TTI placement was successful in 106 of 109 (98%) subjects assigned to TTI. In 2 cases, TTI could not be placed due to anatomical considerations. Three TTI ventral iliac breaches were observed, all of which were managed non-surgically. One TTI subject had a transverse sacral fracture and 1 TTI subject had malposition of the implant requiring removal.

CONCLUSIONS

SI joint pain is common in patients with adult spinal deformity who are candidates for multilevel spine fusion surgery. Concurrent placement of TTI parallel to S2AI screws during multilevel spine fusion surgery is feasible and safe. Further follow-up will help to determine the clinical value of this approach to augment pelvic fixation.

Percutaneous endoscopic lumbar discectomy for single and double segment lumbar disc herniation with sciatic scoliosis in adults: a retrospective study

OBJECTIVE

Sciatic scoliosis can be seen in patients with lumbar disc herniation. Percutaneous endoscopic lumbar discectomy (PELD) is a common surgical method for the treatment of lumbar disc herniation. The difference between single-segment lumbar disc herniation and double-segment lumbar disc herniation with Sciatic Scoliosis in adults after PELD needs further study. The aim of this study was to compare the imaging features of single-segment and double-segment lumbar disc herniation with Sciatic Scoliosis in adults and to further explore the clinical outcomes of functional improvement and scoliosis imaging parameters of the two groups after PELD.

METHODS

Adult patients with lumbar disc herniation with sciatic scoliosis who received PELD from January 2019 to June 2022 were analyzed retrospectively. According to the number of operative segments, the patients were divided into a single-segment group and a double-segment group. Perioperative parameters were observed and compared between the two groups. The Visual Analogue Scale (VAS) score, Oswestry dysfunction index (ODI), Japanese Orthopaedic Association scores (JOA) and imaging parameters of the two groups were recorded and compared before the operation and during the follow-up.

RESULTS

A total of 53 patients with single segments and 21 patients with double segments were included in this study. During the follow-up, the VAS score, ODI index and JOA score of the two groups were significantly improved as compared with those before the operation(P < 0. 05). Ninety-two point five percent of single-segment patients and 90.5% of double segment patients returned to normal scoliosis within 12 months after the operation. The operation time, number of intraoperative fluoroscopy times and the amount of intraoperative blood loss in single-segment patients were better than those in double-segment group(P < 0. 05). At the last follow-up, the AVT, CBD and SVA in the double-segment group were 5.2 ± 2.3, 5.1 ± 1.0 and 12.2 ± 3.0 mm, respectively, which were higher than those in the single-segment group (1.9 ± 0.4, 1.1 ± 1.6 and 3.9 ± 2.1 mm) (P < 0. 05).

CONCLUSION

PELD is an effective treatment for single-segment and double-segment lumbar disc herniation with Sciatic scoliosis. Double-segment patients can enjoy similar clinical efficacy to single-segment patients, avoiding complications caused by decompression, fusion, and internal fixation. Scoliosis was corrected spontaneously within 12 months after operation, and the sagittal curve was significantly improved in both groups. The improvement of coronal and sagittal balance in double -segment patients may take longer.

Dimple of Venus Is Associated with the Increased Pelvic Incidence Angle and More Sagittally Oriented Facet Joint

OBJECTIVES

The present study aims to investigate whether the dimple of Venus affects the anatomy of spinopelvic junction.

SUBJECTS AND METHODS

Inclusion criteria were having a lumbar MRI examination in the last 1 year, being older than 18 years of age and being able to radiologically evaluate the whole vertebral colon and pelvic girdle. Exclusion criteria were having congenital diseases of the pelvic girdle/hip/vertebral column and history of fracture or previous surgery in the same anatomic regions. The patients' demographic data and low back pain were noted. At radiological examination, the pelvic incidence angle was measured by lateral lumbar X-ray. The facet joint angle, tropism, facet joint degeneration, intervertebral disc degeneration, and intervertebral disc herniation at the level of L5-S1 were examined on lumbar MRIs.

RESULTS

We included 134 male and 236 female patients with a mean age of 47.86 ± 14.50 years and 48.49 ± 13.49 years, respectively. We found that the patients with the dimple of Venus had higher pelvic incidence angle (p < 0.001) and more sagittally oriented facet joint (right facet joint p = 0.017, left facet joint p = 0.001) compared to those without the dimple of Venus. There was no statistically significant relationship between low back pain and the presence of the dimple of Venus.

CONCLUSIONS

The dimple of Venus affects the anatomy of the spinopelvic junction and is associated with an increased pelvic incidence angle and a more sagittally oriented facet joint angle.

The Impact of Spinopelvic Alignment on the Facet Joint Degeneration

STUDY DESIGN

Retrospective Cohort.

OBJECTIVES

This study aims to evaluate the relations between facet joint degeneration (FD) and sagittal spinopelvic parameters. Second, the association of FD with degenerative disc disease (DDD) and lumbar disc herniations (LDH) was assessed.

METHODS

The radiologic data of 192 patients was retrospectively analyzed. Total, proximal, and distal lumbar lordosis (LL, PLL, and DLL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and sacral table angle (STA) were measured on lumbar x-ray plates. DDD and FD was graded on the MRI images. The apex of lumbar lordosis and PI-LL imbalance were noted in each patient. Correlation analyses were performed.

RESULTS

Age and body mass index (BMI) were correlated with FD. LL and DLL are positively associated with upper-level FDs (L1-2 and L2-3) (P < 0,05). PLL were positively associated with lower level FD (L5-S1) (P < 0,05). A significant increase in PI was associated with FD in L2-3 and L4-5. A larger PT was found in FD in L4. The PI-LL imbalance was not correlated with the FD. Correlation between DDD and LDH and FD was observed in each level (P < 0,01). The level of FD is not affected by the apex of the curve.

CONCLUSION

Age and BMI have a direct impact on FD. However, spinopelvic parameters influence the severity of FD rather than its occurrence. In addition to the effects of lumbar lordosis as a single entity, it is essential to consider separately the effects of proximal and distal lumbar lordosis at the FD level.

Intervertebral disc degeneration and osteoarthritis: a common molecular disease spectrum

Intervertebral disc degeneration (IDD) and osteoarthritis (OA) affecting the facet joint of the spine are biomechanically interdependent, typically occur in tandem, and have considerable epidemiological and pathophysiological overlap. Historically, the distinctions between these degenerative diseases have been emphasized. Therefore, research in the two fields often occurs independently without adequate consideration of the co-dependence of the two sites, which reside within the same functional spinal unit. Emerging evidence from animal models of spine degeneration highlight the interdependence of IDD and facet joint OA, warranting a review of the parallels between these two degenerative phenomena for the benefit of both clinicians and research scientists. This Review discusses the pathophysiological aspects of IDD and OA, with an emphasis on tissue, cellular and molecular pathways of degeneration. Although the intervertebral disc and synovial facet joint are biologically distinct structures that are amenable to reductive scientific consideration, substantial overlap exists between the molecular pathways and processes of degeneration (including cartilage destruction, extracellular matrix degeneration and osteophyte formation) that occur at these sites. Thus, researchers, clinicians, advocates and policy-makers should consider viewing the burden and management of spinal degeneration holistically as part of the OA disease continuum.

Wide anatomical variability of PI normative values within an asymptomatic population: a systematic review

PURPOSE

Studies on sagittal alignment parameters have solely focused on patients with preexisting spinal deformity. Limited data in the literature have analyzed pelvic incidence (PI) values in an asymptomatic patient population. The purpose of this study was to: (1) systematically review the literature to analyze normative PI values in asymptomatic patients; and (2) provide a more definitive geometric measurement guide for determining surgical interventions.

METHODS

A systematic review of retrospective studies was performed by searching PubMed to identify studies that analyzed PI measurements in asymptomatic subjects. The following search phrases were used: (pelvic incidence, pelvic tilt, sacral slope, sagittal alignment, radiograph, asymptomatic, normative values, and adults) using Boolean operators AND, OR and NOT. Patients with pathology involving the osseous pelvic anatomy (including fracture, infection, tumor, previous surgery, and lumbosacral fusion) that would prevent measurement of the selected parameters were not included. Pelvic incidence (PI) values were analyzed.

RESULTS

A total of 29 studies met inclusion criteria, including 3629 asymptomatic subjects who underwent standing lateral radiographs (mean age, 41.1 years; range, 24-69 years) for the purposes of analyzing pelvic incidence values. Overall, the mean PI value was 50.0° (range, 24-69) which is consistent with reported values in the literature.

CONCLUSION

Wide anatomical variability and broad clinical interpretation of PI normative values do little to guide surgical planning for successful outcomes. However, this systematic review has presented PI-stratified normative values in a large sample of asymptomatic subjects which can serve as a grounded geometric reference for spine surgeons when considering surgical intervention approaches.

Quantitative evaluation of correlation between lumbosacral lordosis and pelvic incidence in standing position among asymptomatic Asian adults: a prospective study

The determination of lumbopelvic alignment is essential for planning adult spinal deformity surgery and for ensuring favorable surgical outcomes. This prospective study investigated the correlation between the lumbar section of lumbar spine lordosis and increasing pelvic incidence in 324 Asian adults with a mean age of 55 ± 13 years (range: 20-80 years), comprising 115 male and 209 female volunteers. Participants were divided into three groups based on pelvic incidence (G1, G2, and G3 had pelvic incidence of < 45°, 45-55°, and ≥ 55°, respectively). We determined that distal and proximal lumbar lordosis contributed differentially to the increase in pelvic incidence, whereas the lordosis ratio of the L3-L4 and L4-L5 segments mostly remained constant. The mean contribution ratio of the segmental lordosis from L1 to S1 was as follows: L1-L2, 2.3%; L2-L3, 11.7%; L3-L4, 18.1%; L4-L5, 25.2%; and L5-S1, 42.7%. Pelvic incidence had a stronger correlation with proximal lumbar lordosis than did distal lumbar lordosis. The ratios of proximal lumbar lordosis to distal lumbar lordosis were 37.8% in G1, 45.8% in G2, and 55.9% in G3. These findings serve as a reference for future lumbar spine correction or fusion surgery for Asian adults.

Hip-Spine Syndrome in the Nonarthritic Patient

Hip-spine syndrome refers to concurrent hip and spine pathology with overlapping symptoms. Most of the literature has studied it in relation to total hip arthroplasty literature and has been shown to increase dislocation risk. Lumbar spine and pelvic mobility have been studied less frequently in relation to nonarthritic pathologic hip states. Understanding the biomechanical relationship between the lumbar spine, pelvis, and hip can help elucidate how hip-spine syndrome affects the nonarthritic hip and how it impacts outcomes of hip arthroscopy. Changes in lumbar spine motion may be the reason certain predisposed patients develop symptomatic femoroacetabular impingement (FAI) or ischiofemoral impingement. Some athletes may be "hip users" with a low pelvic incidence, making them more reliant on hip motion due to less-intrinsic lumbopelvic motion. When these patients have FAI morphology, their increased reliance on hip motion makes them prone to experiencing femoroacetabular contact and concurrent symptoms. Other athletes may be "spine users," with larger pelvic incidence and more baseline lumbopelvic motion, making them less reliant on hip motion and therefore less prone to experiencing hip impingement even with hip FAI morphology. Hip-spine syndrome also appears to have an impact on patient selection, role of nonoperative treatment, and hip arthroscopy surgical outcomes. Identifying patients with concurrent pathology may allow surgeons to recommend targeted physical therapy or counsel patients better on their expectations after surgery.

Evaluating the sagittal spinal and pelvic parameters in Marfan syndrome patients affected by scoliosis

INTRODUCTION

Spinal deformities present a common finding in patients affected with Marfan syndrome (MFS). More specifically, sagittal spine imbalances reflect the typical finding of such deformities. Observing spino-pelvic radiographs, we focused on eliciting any correlation between the pelvic incidence (PI), sacral slope (SS) and thoracolumbar kyphosis measurements, and categorising them according to a sagittal spinal classification system.

MATERIALS AND METHODS

One hundred seventy patient records were found over a 6 year period, and further refined to incorporate a total of 44 patients. 25 males and 19 females with an average age of 20 years at imaging. Electronic and hard copies of radiographs were used and measurements were made with virtual Cobb meters, rulers and protractors.

RESULTS

The mean PI was significantly different between type-I (46°) and type-II spines (35°) (p = 0.04), and the values for each class were as follows: type IA-53°, type IB-44°, type IC-36°, type IIA-42°, and type IIB-34°. Type II spines had a lower PI compared to type IA spines (p = 0.037) and to that of an unaffected population. Statistically significant differences were noted in SS between groups (t test; p < 0.001), and ANOVA demonstrated that the largest differences between spinal classes were found in SS.

CONCLUSION

In our study, PI values were much higher in type I compared to type II spines. Type II spines had PI values as expected, however, had higher than expected SS values. SS followed a down trending pattern across all spinal classes. Type IIA spines had a much greater preponderance for male patients. Overall, we wish to highlight in particular that type II spines were associated with a much lower PI and SS, and report these differences in pelvic morphology and sagittal spine patterns seen in MFS patients. The pelvic tilt and sacral slope parameters observed in our Type II spines may further reflect and characterize the deformity.

The Kinematic and Kinetic Responses of the Trunk and Lower Extremity Joints during Walking with and without the Spinal Orthosis

Spinal orthoses are an effective option for restoring the spine to its original position and controlling poor posture. However, the effects of poor posture and spinal orthoses on the kinematics and kinetics of trunk and lower extremity joints remain unclear. A six-camera Vicon motion capture system and two AMTI force plates were employed to collect gait parameters, including joint angle (spine, thorax, hip, knee, and ankle), range of motion (ROM), and ground reaction forces (GRFs). Furthermore, joint moments and joint reaction forces (JRFs) were calculated using a full-body musculoskeletal model in OpenSim. One-way repeated-measures ANOVA (p < 0.05) was used to compare significant differences among three trial conditions. These three conditions were walking in a normal posture, poor posture, and spinal orthosis. The results showed that spine ROM in the coronal and transverse plane was significantly lower when walking with a spinal orthosis compared to walking in normal and poor posture (p < 0.05). Compared to normal posture, the lumbar moments and back compressive forces were significantly increased when walking in poor posture (p < 0.05). However, when walking with a spinal orthosis, there was a significant decrease in trunk moments and reaction forces compared to walking in poor posture (p < 0.05). Individuals with poor posture could potentially induce instability and disorders, as evidenced by an increase in trunk moments and JRF compared to the normal posture. Spinal orthosis not only restricts spine ROM but also reduces the load on the spine and thus increases balance and stability.

Functional outcomes are preserved in adult acetabular dysplasia with radiographic evidence of lumbosacral spine anomalies: an investigation in hip-spine syndrome

Purpose

Acetabular dysplasia (AD) is a debilitating condition which results in impaired hip function, leading to hip-spine syndrome with anomalies identifiable on plain radiographs. However, no study to date has investigated the association between radiographic spine anomalies and functional outcomes in AD. We hypothesize that AD patients with radiographic evidence of lumbar spine anomalies are associated with decreased function in comparison to those without such radiographic findings.

Patients and methods

One hundred thirty-five hips underwent a full four-view hip radiograph series, and two observers analyzed hip and spine variables using standard radiographs and obtained Castellvi grade, assessment of spondylolisthesis, and L4-S1 interpedicular distance. A comprehensive hip questionnaire was administered which included Harris Hip Score (HHS) and Hip Disability and Osteoarthritis Outcome Score (HOOS) to assess patient function. Correlations between HHS and HOOS and radiographic spinal measurements were calculated, and p-values were corrected for multiple comparison using the Holm’s method.

Results

Out of 135 patients, 119 were female (88.1%) and 16 were male (11.9%). Average age of presentation was 34.2 years, and average BMI was 26. There was no statistically significant correlation between Castellvi grade, presence of spondylolisthesis, or L4-S1 interpedicular distance and the patient-reported outcome measures HHS or HOOS. Conversely, a significant correlation was observed between Femoro-Epiphyseal Acetabular Roof (FEAR) index and HOOS of the contralateral hip (correlation coefficient = 0.38, adjusted p = 0.03) and Tönnis angle of AD severity and HHS of the contralateral hip (correlation coefficient = − 0.33, adjusted p = 0.04).

Conclusion

Severity of spinal anomalies measured by Castellvi grade and spondylolisthesis in patients with AD was not associated with decreased patient function in the ipsilateral diseased hip. To our knowledge, this is the first study to date to report the relationship between radiographically identifiable lumbosacral abnormalities and hip function in AD.

The significant relationship among the factors of pelvic incidence, standing lumbar lordosis, and lumbar flexibility in Japanese patients with hip osteoarthritis: A descriptive radiographic study

INTRODUCTION

Spine stiffness is known to increase the risk of total hip replacement (THR) instability. The sagittal posture and lumbo-pelvic kinematics have therefore become parameters of interest when planning THR. We conducted this study to investigate (1) the distribution and characteristics of the spino-pelvic standing alignment, (2) the relationship between pelvic incidence (PI) and standing lumbar lordosis (LL) and lumbar flexibility, in Japanese hip osteoarthritis patients.

HYPOTHESIS

(1) Japanese hip osteoarthritis patients with different sagittal spino-pelvic alignments do not differ markedly in their demographics, PI, or lumbar flexibility; and (2) there is no significant relationship between PI, standing LL, and lumbar flexibility in a population of Japanese hip osteoarthritis patients.

MATERIAL AND METHODS

A retrospective study of radiographs from 945 Japanese patients who consecutively received THR for the treatment of hip osteoarthritis. All patients pre-operatively underwent lateral standing and deep-seated lumbo-pelvic radiography on which the spino-pelvic parameters were measured. The difference between the standing and deep-seated LL angles defined the lumbar flexibility and was calculated as the delta (Δ) LL. Individual spino-pelvic standing alignment was stratified based on the difference between the PI and standing LL ('PI-LL mismatch'). 'PI-LL mismatch' of<-10°, between -10° and 10°, and>10° was defined as hyperlordosis, normolordosis, and flatback, respectively.

RESULTS

In the present study, the spinal alignment of 115/945 (12.2%), 559/945 (59.2%), and 271/945 (28.6%) patients were classified as hyperlordosis, normolordosis, and flatback, respectively. Hyperlordotic patients had significantly lower PI (47.6°±7.8° vs. 52.7°±10.5°, p<0.001) and higher ΔLL (60.6°±12.6° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. Patients with flatback were significantly older (age, 69.1±9.1 years vs. 62.7±9.8 years, p<0.001) with higher PI (56.9°±11.7° vs. 52.7°±10.5°, p<0.001) and lower ΔLL (35.2°±17.4° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. A significant relationship between PI and the standing LL was found in the whole cohort (r=0.409, p=0.009), hyperlordotic (r=0.785, p<0.001), normolordotic (r=0.857, p<0.001), and flatback (r=0.664, p<0.001) patients. Significant relationships between the PI and ΔLL were also found in normolordotic (r=0.442, p=0.004) and flatback (r=0.449, p=0.003) patients but not hyperlordotic patients (r=0.154, p=0.367).

DISCUSSION

A large proportion of Japanese hip osteoarthritis patients have abnormal PI-LL mismatch (12% and 29% have hyperlordosis and flatback, respectively). The PI was a determinant of the standing LL and the lumbar flexibility, especially in the normolordotic and flatback individuals.

LEVEL OF EVIDENCE

III; retrospective diagnostic radiographic study.

Pelvic incidence significance relative to spinopelvic risk factors for total hip arthroplasty instability

AIMS

Pelvic incidence (PI) is a position-independent spinopelvic parameter traditionally used by spinal surgeons to determine spinal alignment. Its relevance to the arthroplasty surgeon in assessing patient risk for total hip arthroplasty (THA) instability preoperatively is unclear. This study was undertaken to investigate the significance of PI relative to other spinopelvic parameter risk factors for instability to help guide its clinical application.

METHODS

Retrospective analysis was performed of a multicentre THA database of 9,414 patients with preoperative imaging (dynamic spinopelvic radiographs and pelvic CT scans). Several spinopelvic parameter measurements were made by engineers using advanced software including sacral slope (SS), standing anterior pelvic plane tilt (APPT), spinopelvic tilt (SPT), lumbar lordosis (LL), and PI. Lumbar flexion (LF) was determined by change in LL between standing and flexed-seated lateral radiographs. Abnormal pelvic mobility was defined as ∆SPT ≥ 20° between standing and flexed-forward positions. Sagittal spinal deformity (SSD) was defined as PI-LL mismatch > 10°.

RESULTS

PI showed a positive correlation with parameters of SS, SPT, and LL (r-value range 0.468 to 0.661). Patients with a higher PI value showed higher degrees of standing LL, likely as a compensatory measure to maintain sagittal spine balance. There was a positive correlation between LL and LF such that patients with less standing LL had decreased LF (r = 0.49). Similarly, there was a positive correlation between increased SSD and decreased LF (r = 0.54). PI in isolation did not show any significant correlation with lumbar (r = 0.04) or pelvic mobility (r = 0.02). The majority of patients (range 89.4% to 94.2%) had normal lumbar and pelvic mobility regardless of the PI value.

CONCLUSION

The PI value alone is not indicative of either spinal or pelvic mobility, and thus in isolation may not be a risk factor for THA instability. Patients with SSD had higher rates of spinopelvic stiffness, which may be the mechanism by which PI relates to THA instability risk, but further clinical studies are required. Cite this article: Bone Joint J 2022;104-B(3):352-358.

Locomotive Syndrome and Lumbar Spine Disease: A Systematic Review

Locomotive syndrome (LS) is defined based on the Loco-Check, 25-question Geriatric Locomotive Function Scale (GLFS-25), 5-question Geriatric Locomotive Function Scale (GLFS-5), Stand-Up Test, Two-Step Test, or a total assessment (i.e., positive for one or more of the GLFS-25, Stand-Up Test, and Two-Step Test). Lumbar spine disease has been reported to be one of the most common musculoskeletal disorders leading to LS. We therefore conducted a systematic review via PubMed, Google Scholar, Cochrane Library, Web of Science, and MEDLINE, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 26 studies were considered to be eligible for inclusion in this systematic review. The GLFS-25 showed an association with low back pain, sagittal spinopelvic malalignment, and lumbar spinal stenosis but not vertebral fracture. The GLFS-5 showed an association with low back pain and lumbar spinal stenosis. The Loco-Check and Two-Step Test showed an association with low back pain, sagittal spinopelvic malalignment, and lumbar spinal stenosis. The Stand-Up Test showed no association with lumbar spinal stenosis. The total assessment showed an association with low back pain and lumbar spinal stenosis. Furthermore, the GLFS-25, Two-Step Test, and total assessment were improved by spinal surgery for lumbar spinal stenosis. The current evidence concerning the relationship between LS and lumbar spine disease still seems insufficient, so further investigations are required on this topic.

VALIDATION OF MEASURING PI USING CT AND A COMPARISON WITH WHOLE SPINE AND LUMBOSACRAL X-RAYS

ABSTRACT Objective: The objective of this study is to describe a new, extremely simple method for measuring pelvic incidence (PI) using computed tomography (CT) and to compare those measurements with measurements derived from whole spine and lumbosacral X-rays in a Brazilian population. Methods: Patients who had whole spine and lumbosacral X-rays and whole abdomen, pelvis, or lumbar spine CT performed within a period of less than three months were selected. Image overlay was used to measure PI from the CT. The PI was calculated by two independent examiners, and the PI for each exam was calculated twice, with an interval of two months between the assessments. The intra- and interexaminer reliability and reproducibility were evaluatedusing the intraclass correlation coefficient (ICC) and the repeatability coefficient, considering a 95% confidence interval. Results: Fifty-five patients of both sexes with a mean age of 58.7 years (±19) were analyzed. The mean PI angles in the analyses of both examiners at both evaluations were 54.85° (±13.73) for the whole spine X-ray, 54.06° (±11.67) for the lumbosacral spine X-ray, and 49.96° (±9.85) for the CT. There was good intra- and interexaminer reliability and reproducibility. There was also high concordancewith the whole spine and lumbosacral X-rays. Conclusion: CT is a reliable and reproducible alternative for measuring PI. Level of Evidence III; Prospective comparative.

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.

Optimal Cut-Off Points of Sagittal Spinopelvic Parameters as a Morphological Parameter to Predict Efficiency in Nerve Block and Pulsed Radiofrequency for Lumbar Facet Joint Pain: A Retrospective Study

Background

After proper patient selection, anatomically correct pulsed radiofrequency of the lumbar facet joints provide long-term pain relief in a routine clinical setting. In the study, we performed an analysis of clinical and radiological predictive factors and provide the scientific basis for this promising modality.

Methods

The study included 198 patients with lower back pain due to lumbar facet joint disease who underwent medial branch block and pulsed radiofrequency during the period 2015–2019. According to the improvement in pain score, the patients were divided into good and poor outcome groups. Clinical and radiological data were collected and analyzed.

Results

The multivariable analysis revealed the predictive factors, including lumbar lordosis, lower lumbar lordosis, pelvic tilt, the number of facet joints, old compression fracture with/without vertebroplasty, and post lumbar fusion procedures.

Conclusion

With the results of this study, we demonstrated that the improved outcome after the surgery was related to lumbar lordosis, lower lumbar lordosis, pelvic tilt, the number of facet joints, old compression fracture with/without vertebroplasty, and the lumbar fusion procedures. Old compression fractures and lumbar fusion would change the radiological factors and cause refractory lumbar facet joint pain.

Comparison of sacroiliac joint degeneration between patients with sagittal imbalance and lumbar spinal stenosis

PURPOSE

The purpose of this study was to compare the degeneration of sacroiliac joints (SIJs) between adult spinal deformity (ASD) patients with sagittal imbalance and an age- and sex-matched lumbar spinal stenosis (LSS) patients without sagittal imbalance.

MATERIALS AND METHODS

The age- and sex-matched case-control study consists of two groups: the ASD group and the other group consisting of patients with LSS (LSS group). The study population consisted of 98 patients in each group. The spinopelvic parameters such as pelvic incidence (PI), sacral slope, pelvic tilt, lumbar lordosis, and sagittal vertical axis (SVA) were measured. To evaluate degeneration of SIJ, two protocols (Backlund's grade and Eno's classification) were used.

RESULT

SIJ degeneration in the ASD group was more severe than that in the LSS group, as assessed by both Backlund's grade and Eno's classification (P < 0.001 for both). Age correlated significantly with PI in both the ASD and LSS groups (r = 0.285; P = 0.005, r = 0.218; P = 0.031, respectively). The total Backlund's grading score and the SVA were significantly correlated with PI in the ASD group (r = 0.344; P < 0.001, r = 0.276; P = 0.007, respectively), but not in the LSS group (r = 0.156; P = 0.126, r = 0.189; P = 0.067, respectively).

CONCLUSIONS

ASD patients with sagittal imbalance demonstrated more severe SIJ degeneration compared to the age- and sex-matched LSS group. PI was significantly correlated with both SIJ degeneration and SVA only in the ASD group.

Sagittal Spinopelvic Alignment in Asymptomatic Iranian Adults Aged 18 to 40 Years

BACKGROUND

Recent studies have revealed the increasing importance of sagittal spinopelvic alignment. Knowing the values of sagittal spinopelvic parameters, which are affected by ethnicity, is essential in the normal asymptomatic population. In the current study, these parameters were measured in a sample of asymptomatic Iranian population.

METHODS

Seventy asymptomatic participants without complaint of musculoskeletal problems were enrolled. They had no complaint about musculoskeletal problems. Lateral full-length spinal and pelvic x-rays were taken. The following parameters were measured on x-rays and presented as mean ± standard deviation: pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), thoracic kyphosis (TK), lumbar tilt (LT) and thoracic tilt (TT).

RESULTS

The population consisted of 37 males and 33 females aged 26.6 ± 4.27 years. The mean values of PI, SS, PT, LL, TK, LT, and TT were 44.5 ± 10.1, 35.4 ± 6.7, 9.1 ± 7.9, 41.9 ± 14.7, 28.8 ± 8.3, 11.9 ± 7.4 and -7.5 ± 5.7 (median: -10; 5th percentile: -14; 95th percentile: 4.4) degrees, respectively. The variables were similar between males and females except for LL which was significantly higher in females (37.8 ± 16.5 versus 46.5 ± 11; P = 0.013). In addition, the linear regression model revealed age to be independently related with PI (beta = 0.344; P = 0.004) and PT (beta = 0.366; P = 0.002). PI (r = 0.344, P = 0.004) and PT (r = 0.359, P = 0.002) were positively correlated with age. Additionally, PI was positively correlated to SS, PT and LL and negatively to TT.

CONCLUSION

These findings may be used as referential values for sagittal spinopelvic parameters in the Iranian population. The positive correlation of PI with age questions the constancy of PI throughout life. However, larger studies are required.

Three-dimensional analysis of acetabular cup orientation and an evaluation of the relationship with pelvic sagittal parameters

BACKGROUND

This study aimed to evaluate the effect of total hip arthroplasty (THA) on sagittal pelvic parameters and to evaluate the effect of sagittal pelvic parameters on acetabular cup orientation.

METHODS

The study included 86 patients who underwent THA for a diagnosis of unilateral coxarthrosis between 2011 and 2015. Measurements were taken of the preoperative and postoperative acetabular cup inclination (ACI), anteversion, and sagittal pelvic parameters. The effect of THA on sagittal pelvic parameters and the effects of the sagittal pelvic parameters on acetabular cup orientation were investigated.

RESULTS

The sagittal pelvic tilt values calculated were mean 9.7° ± 6.3° (2°; 23°) preoperatively and 11.0° ± 6.1° (2°; 25°) postoperatively. The increase in postoperative pelvic incidence (PI) values was determined to be statistically significant (p < 0.05). The preoperative PI values had no significant effect on ACI, but in cases with high preoperative PI values, a tendency to high anteversion values was determined. The mean inclination values were found to be 40.2° ± 11.0° in the low PI group, 41.7° ± 7.4° in the normal PI group, and 44.1° ± 8.3° in the high PI group. As no increase in inclination values was observed with an increase in PI values, no statistical correlation was determined (p = 0.343). Average of anteversion values in the low PI group was 9.2° ± 13.7°, in the normal PI group 19.3° ± 10.5°, and in the high PI group 21.1° ± 12.5°. The difference between the groups was statistically significant (p = 0.001).

CONCLUSION

Evaluating the results of this study, it can be concluded that varying PI values do affect the acetabular cup anterversion in THA. So, preoperative assessment of PI values is important in preventing postoperative acetabular cup malposition.

Spinopelvic alignment predicts disc calcification, displacement, and Modic changes: Evidence of an evolutionary etiology for clinically-relevant spinal phenotypes

Lumbar disc-displacement, Modic changes (MCs), and UTE Disc Sign (UDS) on MRI are clinically relevant spinal phenotypes that can lead to sciatica/LBP. Not all degenerated discs result in disc-displacement, MCs and UDS, suggesting varied etiologies. Spinopelvic parameters have been implicated in various spinal disorders. Pelvic incidence (PI) is "fixed parameter" since skeletal maturity. No study has addressed disc-displacement, MCs and UDS in context of spinopelvic parameters. Therefore, the aim of study was to determine if spinopelvic parameters are associated and predict clinically-relevant MRI-phenotypes. One hundred and eight population-based subjects (mean age: 52.3 years) were recruited. Spondylolisthesis and scoliosis individuals were excluded. Lumbar lordosis (LL), PI, sacral slope (SS), and pelvic tilt (PT) were assessed on lateral plain radiographs. Disc degeneration was assessed and summated, and presence or not of disc-displacement and MCs were noted on T2W MRI. UDS was detected on UTE. Following exclusion criteria, 95 subjects were assessed. Disc-displacement (82.1%), MCs (52.6%), and UDS (37.9%) were associated with lower PI, SS, LL, and LL/PI index. On multivariate analyses, lower PI was significantly related to development of these MRI phenotypes (adjusted OR range:0.95-0.92; P < .05), with critical PI value of 42° or lower exhibiting fourfold increase risk of combined phenotypes (P = .020). Of UDS discs, 39.3% had adjacent MCs and 83.6% had disc-displacement. 87.5% of MC had directly adjacent UDS. The first study to note that PI may "predict" the development of disc-displacement, MCs and UDS, suggesting potential sub-variants and mechanistic susceptibility that may be grounded in spinopelvic evolution. An "evolutionary etiological pathway" of spinal phenotype development is proposed.

Lumbar spine posture and spinopelvic parameters change in various standing and sitting postures

PURPOSE

This study aimed to compare differences in lumbosacral and spinopelvic parameters between pain developers and non-pain developers as well as the effects of various posture changes.

METHODS

A total of 38 consecutive participants, 20 standing-induced low back pain developers (mean age: 27.7 ± 5.3; mean BMI: 22.64 ± 2.95) and 18 non-pain developers (mean age: 29.0 ± 7.5; mean BMI: 24.2 ± 1.87) (p > 0.05), were prospectively evaluated. Six sagittal plane radiographs were taken. Upright standing posture was used as the reference posture. Lumbar lordosis, lumbosacral lordosis, L1/L2 and L5/S1 intervertebral (IV) joint angles, pelvic incidence, pelvic tilt and sacral slope were measured on each radiograph.

RESULTS

There were no significant differences in terms of age, BMI, SF-36 score, or Oswestry Disability Index scores between pain developer and non-pain developer groups (p > 0.05). Pain developers had significantly larger lumbar lordosis, larger L1/L2 intervertebral angles, larger pelvic incidences and sacral slopes in all postures (p < 0.05). The contribution of L5/S1 intervertebral angle to lumbar flexion was higher than that of the L1/L2 intervertebral angle during stair descent, the sitting and the leaning forward while sitting postures (p < 0.05).

CONCLUSION

The current study supports the assertion that increased lumbar lordosis is associated with increased pain. Lumbar spine angles change in various postures. The changes were more prominent in pain developers than in non-pain developers. Larger lumbar lordosis due to larger pelvic incidence may be a risk factor for the development of standing-induced low back pain. These slides can be retrieved under Electronic Supplementary Material.

The influence of spinopelvic parameters on adjacent-segment degeneration after short spinal fusion for degenerative spondylolisthesis

OBJECTIVE

Spinopelvic parameters, such as the pelvic incidence (PI) angle, sacral slope angle, and pelvic tilt angle, are important anatomical indices for determining the sagittal curvature of the spine and the individual variability of the lumbar lordosis (LL) curve. The aim of this study was to investigate the influence of spinopelvic parameters and LL on adjacent-segment degeneration (ASD) after short lumbar and lumbosacral fusion for single-level degenerative spondylolisthesis.

METHODS

The authors retrospectively reviewed the records of all short lumbar and lumbosacral fusion surgeries performed between August 2003 and July 2010 for single-level degenerative spondylolisthesis in their orthopedic department.

RESULTS

A total of 30 patients (21 women and 9 men, mean age 64 years) with ASD after lower lumbar or lumbosacral fusion surgery comprised the study group. Thirty matched patients (21 women and 9 men, mean age 63 years) without ASD comprised the control group, according to the following matching criteria: same diagnosis on admission, similar pathologic level (≤ 1 level difference), similar sex, and age. The average follow-up was 6.8 years (range 5-8 years). The spinopelvic parameters had no significant influence on ASD after short spinal fusion.

CONCLUSIONS

Neither the spinopelvic parameters nor a mismatch of PI and LL were significant factors responsible for ASD after short spinal fusion due to single-level degenerative spondylolisthesis.

Pelvic incidence variation among individuals: functional influence versus genetic determinism

Pelvic incidence has become one of the most important sagittal parameters in spinal surgery. Despite its great importance, pelvic incidence can vary from 33° to 85° in the normal population. The reasons for this great variability in pelvic incidence remain unexplored. The objective of this article is to present some possible interpretations for the great variability in pelvic incidence under both normal and pathological conditions and to further understand the determinants of pelvic incidence from the perspective of the functional requirements for bipedalism and genetic backgrounds via a literature review. We postulate that both pelvic incidence and pelvic morphology may be genetically predetermined, and a great variability in pelvic incidence may already exist even before birth. This great variability may also serve as a further reminder that the sagittal profile, bipedal locomotion mode, and genetic background of every individual are unique and specific, and clinicians should avoid making universally applying broad generalizations of pelvic incidence. Although PI is an important parameter and there are many theories behind its variability, we still do not have clear mechanistic answers.

The Relationship between Sacral Kyphosis and Pelvic Incidence

Study Design

Retrospective cohort study.

Purpose

Evaluate the fixed anatomical parameter of sacral kyphosis (SK) and its relationship with pelvic incidence (PI).

Overview of Literature

Pelvic parameters determine pelvic and lumbar spinal position. Studies have defined normative values, and have evaluated the role of these parameters in clinical practice. It has been suggested that a ratio of sacral slope (SS)/PI <0.5 predisposes to spinal pathology. PI=SS+pelvic tilt (PT) and therefore for a given PI, patients with a higher SS due to an elevated SK will potentially predispose to an unfavourable SS/PI ratio.

Methods

CT measurements of SS and PI were made in 100 consecutive patients from our database. Imagings without clear landmarks were excluded. PI and SK were measured using standardised techniques. Pearson's correlation was used to assess association between PI and SK, in addition to the correlation between age and the pelvic parameters. Gender specific values for PI and SK were compared using an unpaired Student t-test.

Results

Ninety-five patients (52 females) with a mean age 51.3 years were available for analysis. A strong positive correlation between the PI and the SK was identified (Pearson's coefficient=0.636, R² value=0.404). Neither PI nor SK had a statistically significant correlation with age (p=0.721 and p=0.572, respectively). The mean values of both the PI and SK were statistically significantly lower in females when compared to males (p=0.0461 and p=0.0031, respectively).

Conclusions

A strong correlation between PI and SK exists and is a reflection of different pelvic morphologies. SK partially determines SS and a relatively high SK compared to PI will result in less ability to change PT and a potentially unfavourable SS/PI ratio, which could theoretically contribute to clinical pathology.

Pelvic Incidence Can Be Changed not only by Age and Sex, but also by Posture Used during Imaging

OBJECTIVE

Computed tomography (CT), rather than conventional 2-dimensional radiography, was used to scan and measure pelvic parameters. The results were compared with measurements using X-ray.

METHODS

Pelvic parameters were measured using both CT and X-ray in 254 patients who underwent both abdomino-pelvic CT and X-ray at the pelvic site. We assessed the similarity of the pelvic parameters between the 2 exams, as well as the correlations of pelvic parameters with sex and age.

RESULTS

The mean values of the subjects' pelvic parameters measured on X-ray were: sacral slope (SS), 31.6°; pelvic tilt (PT), 18.6°; and pelvic incidence (PI), 50.2°. The mean values measured on CT were: SS, 35.1°; PT, 11.9°; and PI, 47.0°. PT was found to be 4.07° higher on X-ray and 2.98° higher on CT in women, with these differences being statistically significant (p<0.001, p<0.001). PI was 4.10° higher on X-ray and 2.78° higher on CT in women, with these differences also being statistically significant (p<0.001, p=0.009). We also observed a correlation between age and PI. For men, this correlation coefficient was 0.199 measured using X-ray and 0.184 measured using CT. For women, this correlation coefficient was 0.423 measured using X-ray and 0.372 measured using CT.

CONCLUSION

When measured using CT compared to X-ray, SS increased by 3.5°, PT decreased by 6.7°, and PI decreased by 3.2°. There were also statistically significant differences in PT and PI between male and female subjects, while PI was found to increase with age.

Characterisation of the correlation between standing lordosis and degenerative joint disease in the lower lumbar spine in women and men: a radiographic study

BACKGROUND

Degenerative joint disease (DJD) in the lumbar spine is a common condition that is associated with chronic low back pain. Excessive loading of lumbar joints is a risk factor for DJD. Changes in lumbar lordosis significantly redistribute the forces of weight-bearing on the facet joints and the intervertebral discs. However, the relationship between lumbar lordosis and DJD has not been characterized in men and women.

METHODS

We characterised the correlation between standing lumbar lordosis and DJD in standing radiographic images from 301 adult female and male chiropractic patients. DJD was rated using the Kellgren-Lawrence scale, and lordosis was measured using the Cobb angle. Linear and curvilinear correlations were investigated while controlling for age and sex.

RESULTS

We found a highly significant curvilinear correlation between lordosis and DJD of the lower lumbar spine in both sexes, but especially in women, irrespective of the effects of age. We found the effect size of lordosis on lower lumbar DJD to be between 17.4 and 18.1% in women and 12.9% in older men. In addition, lordosis of 65 (95% CI 55.3-77.7) and 68 (98% CI 58.7-73.3) degrees were associated with minimal DJD in the lower lumbar spine of women and men respectively, and were therefore considered 'optimal'. This optimal lordotic angle was 73 (95% CI 58.8-87.2) degrees in older men.

CONCLUSIONS

Both hypo- and hyper-lordosis correlate with DJD in the lumbar spine, particularly in women and in older men. These findings may well be of relevance to spinal pain management and spinal rehabilitation.

Finite element analysis of sagittal balance in different morphotype: Forces and resulting strain in pelvis and spine

In humans, vertical posture acquisition caused several changes in bones and muscles which can be assumed as verticalization. Pelvis, femur, and vertebral column gain an extension position which decreases muscular work by paravertebral muscles in the latter. It's widely known that six different morphological categories exist; each category differs from the others by pelvic parameters and vertebral column curvatures. Both values depend on the Pelvic Incidence, calculated as the angle between the axes passing through the rotation centre of the two femur heads and the vertical axis passing through the superior plate of the sacrum. The aim of this study is to evaluate the distribution of stress and the resulting strain along the axial skeleton using finite element analysis. The use of this computational method allows performing different analyses investigating how different bony geometries and skeletal structures can behavior under specific loading conditions. A computerized tomography (CT) of artificial bones, carried on at 1.5 mm of distance along sagittal, coronal and axial planes with the knee at 0° flexion (accuracy 0.5 mm), was used to obtain geometrical data of the model developed. Lines were imported into a commercial code (Hypermesh by Altair®) in order to interpolate main surfaces and create the solid version of the model. In particular six different models were created according Roussoly's classification, by arranging geometrical position of the skeletal components. Loading conditions were obtained by applying muscular forces components to T1 till to L5, according to a reference model (Daniel M. 2011), and a fixed constrain was imposed on the lower part of the femurs. Materials were assumed as elastic with an Elastic modulus of 15 GPa, a Shear Modulus of 7 GPa for bony parts, and an Elastic modulus of 6 MPa, a Shear Modulus of 3 MPa for cartilaginous parts. Six different simulations have been carried out in order to evaluate the mechanical behavior of the human vertebral column arranged according to the Russoly's classification; results confirm higher solicitations obtained varying configurations from case I to case VI. In particular way, first three cases seem to supply the different loading configurations spreading stresses in almost all the bony parts of the column, while the remaining others three cases produce an higher concentration of stress around the lower part of spine (L3, L4, L5). Results confirm a good agreement with those present in literature (Winkle et al., 1999), an equivalent Von Mises average stress was of 0,55 MPa was found on the intervertebral disks with the higher values reached on the lower part of the column. A comparison of results obtained for Case I with literature (Galbusera et al., and El Rich et al., 2004), shows a good agreement in terms of normal compressive force, while more evident differences with Galbusera's results can be found for shear force and sagittal moment. The results underline a relationship between PI increase, and accordingly of PT and LL, and the distribution of load forces. Load forcesi is exerted mainly on distal vertebrae, especially on L4 and L5.

Increased and decreased pelvic incidence, sagittal facet joint orientations are associated with lumbar spine osteoarthritis in a large cadaveric collection

PURPOSE

Degenerative joint disease of the lumbar spine is a pervasive problem in healthcare; however, its aetiology and risk factors remain poorly defined. There have been recent attempts to correlate the anatomic parameters of facet angle and pelvic incidence with spine osteoarthritis, although data remains limited. The purpose of this experiment was to determine how age, gender, race, facet angle, tropism, and pelvic incidence correlate to facet joint osteoarthritis in the lumbar spine.

METHODS

A total of 576 cadaveric lumbar spines were obtained. Using validated techniques, facet angle, tropism, and pelvic incidence were measured. Osteoarthritis of the lumbar spines was graded from 0-4 at each level. Correlations between osteoarthritis and age, gender, facet angle, tropism, and pelvic incidence were evaluated with regression analysis.

RESULTS

Facet angle became more coronally oriented, and facet tropism increased from L1-L2 to L5-S1. Arthritis was highest at the L4-L5 joint (2.2 ± 1.1), compared to the L5-S1 (2.1 ± 1.1), L3-L4 (1.9 ± 1.1), L2-L3 (1.5 ± 1.0) and L1-L2 (1.0 ± 1.0) joints (p < 0.001). Age was the strongest predictor of arthritis at all levels (standardized betas 0.342 through 0.494, p < 0.001). Correlations between gender, race and osteoarthritis were not significant at any level. A decreased facet angle was predictive of increased arthritis at each joint level (standardized betas -0.091 through -0.153, p < 0.05 for all). Tropism was a predictor of increased arthritis at caudal levels. Pelvic incidence was a predictor of increased arthritis at L3-L4 (standardized beta 0.080, p = 0.02), L4-L5 (standardized beta 0.081,p = 0.02), and L5-S1 (standardized beta 0.100, p = 0.01).

CONCLUSIONS

Facet arthritis was correlated with a more sagittal orientation of the facet joints, increased tropism, and perturbations of pelvic incidence.

Increased Pelvic Incidence is Associated With a More Coronal Facet Orientation in the Lower Lumbar Spine: A Cadaveric Study of 599 Lumbar Spines

STUDY DESIGN

An anatomic study of facet angle orientation and morphology of the lumbar spine was performed.

OBJECTIVE

The aim of this study was to determine how age, gender, race, and pelvic incidence (PI) correlate with facet orientation in the lumbar spine.

SUMMARY OF BACKGROUND DATA

Lumbar facet orientation has important implications in the development of numerous pathologies of the spine, including arthritis, spondylolisthesis, and adult spinal deformity. Preliminary reports have suggested that sagittal balance of the spine may contribute to facet joint orientation. We therefore designed an anatomic study to investigate the relationship between PI and facet orientation, within the context of age, gender, and race.

METHODS

Five hundred ninety-nine cadaveric lumbar spines were obtained from the Hamann-Todd osteological collection. It was determined that facet angle was most reliably assessed by measuring the angle between the superior articular facet and the spinous process. Facet angles were measured bilaterally at each level from T12-L1 through L5-S1 in every specimen. Multivariate regression analysis was used to determine independent predictors of facet angle at each level.

RESULTS

Facet angle increased rostrally to caudally, from 22.6 ± 8.3° at T12-L1 to 49.1 ± 12.4° at L5-S1. Cadaver age was an independent predictor of a more sagittal facet angle at lower spinal levels. Caucasian race was an independent predictor of increasing facet angle. Increased PI had no effect on facet angle at T12-L1, L1-L2, L2-L3, or L3-L4, although was a significant predictor of more coronally oriented facet joints at L4-L5 (standardized beta 0.096, P = 0.009) and L5-S1 (standardized beta 0.079, P = 0.032).

CONCLUSION

The results of this study provide important data regarding differences in facet angle that exists between individuals. Moreover, the results of this study suggest that facet joints do possess the ability to remodel over time, perhaps in response to perturbations of sagittal balance, osteophyte formation, or other yet to be determined factors.

LEVEL OF EVIDENCE

N/A.

Correlations between the feature of sagittal spinopelvic alignment and facet joint degeneration: a retrospective study

BACKGROUND

Sagittal spinopelvic alignment changes associated with degenerative facet joint arthritis have been assessed in a few studies. It has been documented that patients with facet joint degeneration have higher pelvic incidence, but the relationship between facet joint degeneration and other sagittal spinopelvic alignment parameters is still disputed. Our purpose was to evaluate the correlation between the features of sagittal spinopelvic alignment and facet joint degeneration.

METHODS

Imaging data of 140 individuals were retrospectively analysed. Lumbar lordosis, pelvic tilt (PT), pelvic incidence (PI), sacral slope, and height of the lumbar intervertebral disc were measured on lumbar X-ray plates. Grades of facet joint degeneration were evaluated from the L2 to S1 on CT scans. Spearman's rank correlation coefficient and Student's t-test were used for statistical analyses, and a P-value <0.05 was considered statistically significant.

RESULTS

PI was positively associated with degeneration of the facet joint at lower lumbar levels (p < 0.001 r = 0.50 at L5/S1 and P = 0.002 r = 0.25 at L4/5). A significant increase of PT was found in the severe degeneration group compared with the mild degeneration group: 22.0° vs 15.7°, P = 0.034 at L2/3;21.4°vs 15.1°, P = 0.006 at L3/4; 21.0° vs 13.5°, P = 0.000 at L4/5; 20.8° vs 12.1°, P = 0.000 at L5/S1.

CONCLUSION

Our results indicate that a high PI is a predisposing factor for facet joint degeneration at the lower lumbar spine, and that severe facet joint degeneration may accompany with greater PT at lumbar spine.

Radiographic Signs of Femoroacetabular Impingement Are Associated With Decreased Pelvic Incidence

PURPOSE

To investigate the relation between cam, acetabular version, and pelvic incidence.

METHODS

This was a retrospective analysis of 65 patients with symptomatic hip pain and radiographic signs of femoroacetabular impingement (FAI). Twenty-seven patients were used as a control. All patients received a CT scan of the pelvis that included the sacral endplate. Alpha angle, acetabular version, and pelvic incidence (PI) were measured on 2D CT. Patients were then assigned to 1 of 4 groups: control, cam (alpha angle > 55°, version > 15°), retroverted (alpha angle < 55°, version < 15°), or mixed (alpha angle > 55°, version < 15°).

RESULTS

The PI in mixed-type FAI was 46.7° ± 3.7°, which showed a statistically significant decrease from the PI of the control group, 56.1° ± 4.4° (P = .01). The PI for cam-only deformity was 50.8° ± 4.6°, and the PI for retroverted-only deformity was 51.0° ± 4.6°. Neither was statistically different from the control.

CONCLUSIONS

This study suggests that mixed-type FAI may develop as a response to decreased PI. This result is consistent with previous reports showing decreased PI associated with cam and retroversion deformities. Although the cause of FAI remains controversial, the potential impact of sagittal balance of the pelvis, and specifically, decreased PI, should not be ignored.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Relationship between pelvic incidence and osteoarthritis of the hip

Objectives

Sagittal alignment of the lumbosacral spine, and specifically pelvic incidence (PI), has been implicated in the development of spine pathology, but generally ignored with regards to diseases of the hip. We aimed to determine if increased PI is correlated with higher rates of hip osteoarthritis (HOA). The effect of PI on the development of knee osteoarthritis (KOA) was used as a negative control.

Methods

We studied 400 well-preserved cadaveric skeletons ranging from 50 to 79 years of age at death. Each specimen’s OA of the hip and knee were graded using a previously described method. PI was measured from standardised lateral photographs of reconstructed pelvises. Multiple regression analysis was performed to determine the relationship between age and PI with HOA and KOA.

Results

The mean age was 60.2 years (standard deviation (sd) 8.1), and the mean PI was 46.7° (sd 10.7°). Multiple regression analysis demonstrated a significant correlation between increased PI and HOA (standardised beta = 0.103, p = 0.017). There was no correlation between PI and KOA (standardised beta = 0.003, p = 0.912).

Conclusion

Higher PI in the younger individual may contribute to the development of HOA in later life.

Cite this article: Dr J. J. Gebhart. Relationship between pelvic incidence and osteoarthritis of the hip. Bone Joint Res 2016;5:66–72. DOI: 10.1302/2046-3758.52.2000552.

Correlation of pelvic incidence with radiographical parameters for acetabular retroversion: a retrospective radiological study

Background

Pelvic incidence (PI) has been linked to several degenerative processes within the spinopelvic system. Acetabular retroversion is a recognised risk factor for osteoarthritis of the hip. We therefore hypothesised that these two factors might be part of a specific anatomical variant associated with degenerative changes. This study was performed to clarify this issue.

Methods

The pelvic incidence was measured on 589 computertomographical data sets acquired between 2008 and 2010. For 220 patients a 2D rendering in an antero-posterior view of the CT data set was performed to evaluate the parameters of acetabular retroversion. Those included the prominence of the ischial spine sign (PRISS), the cross-over sign (COS) and the posterior wall sign (PWS). Between 477 and 478 hips were evaluated depending on the parameter of retroversion.

Results

The mean pelvic incidence was significantly lower in hips positive for the PRISS and the PWS. However, there were no significant differences between hips positive or negative for the COS.

Discussion

As hypothesised, the lower PI values in PWS and PRISS positive hips suggest a link between PI and retroversion of the acetabulum. Whether this is of any clinical relevance remains, however, unknown.

Conclusion

Acetabular retroversion is linked to PI. In hips where the prominence of the ischial spine sign and/or the posterior wall sign was present, the mean pelvic incidence value was lower.

The benefits of elective spinal implant removal: a retrospective study of 137 patients

PURPOSE

While spinal instrumentations are becoming more common, the advantages of elective spinal implant removal remain ambiguous. We hypothesized that elective implant removal of the posterior spine is beneficial.

METHODS

A retrospective study evaluated 137 consecutive trauma patients with elective implant removal of the posterior spine. If additional cages were present, they were not removed. Primary outcomes were the change in pre- and post-operative pain, fingertip-floor distance (FFD), and Cobb angles. Some secondary outcomes consisted of complications, work disability, and pelvic incidence (PI). Different stabilization approaches and cage sizes were compared.

RESULTS

The presence and amount of pain as well as the FFD showed significant improvement. There was no loss of reduction. Delayed wound healing was observed in 9%, but only 3% needed revision. Thoracic fascial dehiscences were seen only in patients (9%) that had stand-alone posterior surgery. Larger cages were associated with increased work disability. An increased PI was associated with less post-operative pain and decreased FFD.

CONCLUSIONS

In this study, trauma patients benefited from elective implant removal of the posterior spine due to lower presence and level of pain, improved function and low revision rates; irrespective of an initial combined or stand-alone posterior approach or varying cage sizes. However, stand-alone posterior instrumentation may be accompanied by increased rates of fascial dehiscence surgeries and larger cages may lead to increased work disability. Increased PI may be associated with less pain after spinal implant removal.

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.