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

Evaluating Variations in Spinopelvic Parameters from Sitting to Standing: A Comparative Analysis of 1447 Older Adults Across Age, BMI, and Gender Subgroups

Background/Objectives: Sagittal spinal alignment goals for adult spinal deformity (ASD) surgery are predominantly derived from standing radiographs, despite the biomechanical relevance of sitting posture. Existing studies on sitting alignment involve young, healthy cohorts, which poorly represent ASD patients. This study assessed posture-dependent changes in spinopelvic parameters, including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and lumbar lordosis (LL), and examined how age, BMI, and gender influence these changes. Methods: In this retrospective cohort study, sitting and standing lateral radiographs of 1447 patients were evaluated. Spinopelvic parameters were measured, and changes (ΔPI, ΔPT, ΔSS, and ΔLL) were calculated. Multiple regression analysis was used to determine associations between these changes and age, BMI, and gender. Results: All parameters differed significantly between positions (p < 0.001); PT and PI increased in sitting (ΔPT = -19.20°; ΔPI = -4.52°), while SS and LL increased in standing (ΔSS = 14.67°; ΔLL = 18.44°). Older age correlated with increased ΔPT (p < 0.001) and ΔPI (p = 0.049) but reduced ΔLL and ΔSS (p < 0.001). Higher BMI was associated with decreased ΔPI, ΔPT, and ΔLL (p < 0.001, 0.003, and 0.025). Females showed greater ΔPT (p = 0.013) but smaller ΔPI, ΔSS, and ΔLL (p = 0.043, <0.001, and 0.001). Conclusions: Spinopelvic parameters vary significantly between sitting and standing positions, affected by age, BMI, and gender. The observed PI change suggests SIJ involvement, highlighting the need for posture-specific and demographic-adjusted alignment goals in ASD surgery to optimize outcomes.

Classification of Sagittal Spinopelvic Deformity Predicts Alignment Change After Total Hip Arthroplasty: A Standing and Sitting Radiographic Analysis

BACKGROUND

Changing from standing to sitting positions requires rotation of the femur from an almost vertical plane to the horizontal plane. Osteoarthritis of the hip limits hip extension, resulting in less ability to recruit spinopelvic tilt (SPT) while standing and requiring increased SPT while sitting to compensate for the loss of hip range of motion. To date, the effect of total hip arthroplasty (THA) on spinopelvic sitting and standing mechanics has not been reported, particularly in the setting of patients with coexistent sagittal plane spinal deformity.

METHODS

A retrospective review was performed of patients ≥18 years of age undergoing unilateral THA for hip osteoarthritis with sitting and standing radiographs made before and after THA. Alignment was analyzed at baseline and follow-up after THA in both standing and sitting positions in a relaxed posture with the fingers resting on top of the clavicles. Patients were grouped according to the presence or absence of sagittal plane deformity preoperatively into 3 groups: no sagittal plane deformity (normal), thoracolumbar (TL) deformity (pelvic incidence-lumbar lordosis [PI-LL] mismatch > 10° and/or T1-pelvic angle [TPA] > 20°), or apparent deformity (PI-LL ≤ 10° and TPA ≤ 20°, but sagittal vertical axis [SVA] > 50 mm).

RESULTS

In this study, 192 patients were assessed: 64 had TL deformity, 39 had apparent deformity, and 89 had normal alignment. Overall, patients demonstrated a reduction in standing SVA (45 to 34.1 mm; p < 0.001) and an increase in SPT (14.6° to 15.7°; p = 0.03) after THA. There was a greater change in standing SVA (p < 0.001) among patients with apparent deformity (-29.0 mm) compared with patients with normal alignment (0.9 mm) and patients with TL deformity (-16.3 mm). Those with apparent deformity also experienced the greatest difference (p = 0.03) in postural SPT change (moving from standing to sitting) (-10.1°) from before to after THA when compared with those with normal alignment (-3.6°) and TL deformity (-1.2°). The difference in postural SVA change from before to after THA was also greatest (p < 0.001) in those with apparent deformity (32.1 mm) compared with those with normal alignment (6.5 mm) and TL deformity (17.3 mm).

CONCLUSIONS

Postural changes in spinopelvic alignment vary after THA depending on the presence of TL deformity or apparent deformity due to hip flexion contracture. Patients with apparent deformity had larger changes in standing and sitting alignment than patients with TL deformity or patients with normal alignment. The assessment of global sagittal alignment findings can be used to predict the likelihood of improvement in sagittal alignment after THA.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Spinopelvic alignment and precise cup placement in total hip arthroplasty - A systematic review

Study Design

A systematic literature review and meta- analysis.

Objective

To extract and combine the available literature focused on normal and abnormal biomechanical principles of spine-pelvis-hip complex and to sum up the data in the application of THA both in the setting with and without spinal disorders.

Methods

An extensive search and analysis of the articles was done by 3 authors independently in 7 platforms based on PRISMA and MOOSE guidelines. Selection criteria 1. Articles that assessed spinopelvic parameters (SS, SPT, PI, and acetabular cup orientation) in patients undergoing THA, Articles that assessed balance in spinopelvic complex after THA, Randomized control studies, Systematic literature reviews, Meta-analyses, Clinical trials / original research studies, Review articles and Articles after 2015 were included. Cochrane's GRADE method was used to define the level of evidence. 2.Participants: Patients who underwent THA only (in asymptomatic spine), those who had ankylosing spondylitis and underwent THA and those who underwent THA with prior spinal arthrodesis. 3.Study parameters: Ante Inclination (AI), sacral slope (SS), pelvic Incidence (PI) and spinopelvic tilt (SPT) in both positions of standing and sitting. ΔAI, ΔSS and ΔSPT. Data were collected and analyzed, the means of the study parameters with SD were calculated and a meta-analysis is performed to evaluate the pooled means with optimal value range.

Results

From 218 abstracts extracted and after eligibility assessment and exclusion, 4 articles involving 439 patients were enrolled. The mean SS in standing and sitting calculated were 35.53±10.52 and 33.13±12.38. The mean of AI and SPT in standing /sitting positions are 29.7±12.29/34.69±12.96 (n = 242) and 19.56±8.9/21.22±12.53 (n=439) respectively. The ΔAI, ΔSS, and ΔSPT were 4.99,2.4 and 1.66 respectively.

Conclusion

There is a proportionate change between the spinopelvic tilt and the acetabular orientation in postural variations. Evaluation of spine, pelvis and hip becomes more critical in identifying these changes and thereby prompting the acetabular cup position in the functional safe zone.

Impacts of Hip Osteoarthritis on Spinal Sagittal Alignment and Surgical Outcomes in Patients with Adult Spinal Deformity: Evidence from Meta-analysis and Two-sample Mendelian Randomization

BACKGROUND CONTEXT

A considerable proportion of patients with adult spinal deformity (ASD) have concomitant hip osteoarthritis (HOA). However, no studies have systematically summarized the impacts of HOA on ASD patients, either radiologically or clinically.

PURPOSE

To compare the spinal sagittal alignment parameters pre- and postoperatively, along with patient-reported outcomes and complications following surgery in ASD patients with or without severe HOA (Kellgren-Lawrence grade 3-4).

STUDY DESIGN/SETTING

Systematic review and meta-analysis.

METHODS

We searched the PubMed, Embase, Scopus, Cochrane Library, Google scholar, ClinicalTrials.gov, ProQuest Dissertations and These, and Open Grey for articles with a publication cutoff of July 28, 2024. The inclusion criteria were: (1) comparative studies of ASD patients with and without severe HOA, (2) outcomes reported as spinal radiographic outcomes (such as pelvic tilt (PT), sacrofemoral angle (SFA), knee angle (KA), or sagittal vertical axis (SVA), etc.), patient-reported outcomes (such as SRS-22r, ODI, VR-12 PCS, etc.), and complications (such as proximal junctional kyphosis, pseudarthrosis, reoperation, etc.), and (3) randomized controlled trials and observational studies published in English. The exclusion criteria were (1) reviews, case series, case reports, letters, and conference reports, (2) in vitro biomechanical studies and computational modelling studies, (3) no report on study outcomes, and (4) studies with < 10 patients per group. Additionally, a two-sample mendelian randomization (MR) study using genetic variants associated with HOA as instrumental variables was conducted.

RESULTS

Four observational studies with a total of 891 ASD patients (672 minimal HOA, 219 severe HOA) were included. Based on our meta-analysis, ASD patients with severe HOA exhibited significantly lower PT (95% CI: 0.09-0.57) and SFA (5% CI: 0.31-0.68), along with higher KA (95% CI: -0.52- -0.19), SVA (95% CI: -0.75- -0.41), global sagittal angle (95% CI: -0.71- -0.16), and posterior pelvic shift (95% CI: -0.93- -0.25) than those with minimal HOA. Furthermore, concomitant severe HOA was associated with higher postoperative SVA, worse VR-12 PCS, and increased risk of pseudarthrosis and reoperation based on a review of the literature. The MR study indicated a causal association between HOA and intervertebral disc degeneration related traits, including early lumbar prolapse (95% CI: 1.08-1.46), intervertebral disc disorders (95% CI: 1.07-1.32), and low back pain (95% CI: 1.02-1.17). Moreover, HOA was proven to relate to sarcopenia related traits, including usual walking pace (95% CI: -0.04- -0.02) and hand grip strength (95% CI: -0.06- -0.01).

CONCLUSIONS

Radiologically, concomitant HOA in patients with ASD appears to be associated with limited pelvic compensatory capacity and worse global spinal sagittal alignment. Clinically, ASD patients with HOA may experience worse patient-reported outcomes and higher incidence of mechanical complications. Moreover, the presence of HOA promotes the progression of IVDD and sarcopenia, which could partially account for its impacts.

Impact of the hip osteoarthritis on sagittal spine-pelvis alignment parameters in lumbar spinal stenosis with sagittal malalignment: a propensity score matching study

PURPOSE

There is a paucity of data regarding the sagittal spine-pelvis-leg alignment and the compensatory mechanisms in patients with lumbar spinal stenosis (LSS) and hip osteoarthritis (HOA). In this study, we aim to evaluate the association of HOA with sagittal spine-pelvis alignment parameters in a population of patients with lumbar spinal stenosis and sagittal malalignment.

METHODS

We retrospectively analyzed a cohort of prospectively enrolled patients with degenerative LSS and sagittal malalignment between January 2019 and December 2023. Radiographic parameters evaluated were pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, sagittal vertical axis (SVA), T1-pelvic angle (T1PA), sacrofemoral angle (SFA), pelvic obliquity (PO), and femoral inclination (FI). HOA was graded by Kellgren-Lawrence (K/L) grades and divided into low-grade HOA (LOA; grade 0-2) and severe HOA (SOA; grade 3 or 4) groups. LOA group patients were propensity-score matched (PSM) 1:1 to SOA group patients based on age and PI. Univariate, multivariate, and subgroup analyses were used to analyze the association between HOA and sagittal malalignment.

RESULTS

Out of 379 patients, 116 with LOA and 116 with SOA were analyzed after propensity score matching for age and PI. SOA patients exhibited significantly lower FPA (184.01 ± 9.97 vs 186.78 ± 10.11, p = 0.036), higher SS (33.05 ± 9.38 vs. 30.51 ± 9.47, p = 0.042), and lower PT (16.28 ± 8.67 vs. 18.53 ± 7.84, p = 0.040) compared to the LOA group. Subgroup analysis revealed that SOA patients with a SVA > 4 cm had significantly higher PI (51.49 ± 11.64 vs. 47.83 ± 10.73, p = 0.025) and PT (18.71 ± 8.76 vs. 14.67 ± 8.56, p < 0.001), which were not observed in the LOA group. Multivariable linear regression analysis revealed that a greater Kellgren-Lawrence (K/L) Grade was significantly associated with a higher SVA after adjusting for age, BMI, and PI.

CONCLUSION

In this PSM study, patients with SOA exhibit reduced pelvic tilt and hip extension in standing positions compared to those with LOA. Additionally, the SOA patients had worse global sagittal alignment than their LOA counterparts.

Prevalence of total joint arthroplasty in the adult spine deformity population

PURPOSE

The spine, hip, and knee are anatomically and biomechanically connected. Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are commonly employed to treat degenerative changes in the hip and knee, while fusion is used for spine degeneration. Spine deformity correction results in changes in sagittal alignment and pelvic parameters, and patients with stiff spines have higher rates of THA dislocation and revision due to instability. The goal of this study was to determine the prevalence of total joint arthroplasty (TJA) in adult spinal deformity (ASD) patients at our institution.

METHODS

Following Institutional Review Board approval, we retrospectively reviewed a list of cases performed by the senior author from 4/2017 to 5/2021. Patients > 18 years old undergoing preoperative evaluation for symptomatic lumbar degeneration or ASD were included. Patients < 18 years old, those diagnosed with adolescent idiopathic scoliosis, and non-fusion cases were excluded. Perioperative full-length standing EOS images were examined for the presence or absence of THA, TKA, or both. Demographic data was collected from patient electronic medical records, and statistical analyses were completed.

RESULTS

572 consecutive cases were reviewed, and 322 were excluded. 250 cases (97M:153F) were included in the final analysis, with a mean age of 61.8 ± 11.2 years. A total of 74 patients had a TJA (29.4%). THA was present in 41 patients (16.4%), and TKA was present in 49 patients (19.6%). Males had a higher prevalence of TJA, THA, and TKA (29.9%, 16.5%, and 21.6%) than females (29.4%, 16.3%, and 18.3%).

CONCLUSIONS

This study revealed a high prevalence TJA rate of 29.4% in ASD at our institution. This rate surpasses the prevalence rate reported among the general population in previous studies. High prevalence of patients with ASD and TJA may merit special surgical consideration.

Patients with Hip Osteoarthritis Have a Higher Rate of Spinal Reoperation Following Lumbar Spinal Fusion

BACKGROUND

Lumbar spinal pathology is known to affect outcomes following total hip arthroplasty (THA). However, the effect of hip osteoarthritis (OA) on outcomes following lumbar fusion has not been well studied. The purpose of this study was to determine the association between hip OA and spinal reoperation following lumbar spinal fusion.

METHODS

The 5% Medicare Part B claims database was queried for all patients who underwent primary elective lumbar fusion from 2005 to 2019. Patients were divided into 2 groups: those who underwent elective THA within 1 year after primary lumbar fusion, indicating that they had severe hip OA at the time of lumbar fusion, and those who underwent lumbar fusion with no diagnosed hip OA and no THA during the study period. Exclusion criteria included THA as a result of trauma, revision THA or primary THA in the 5-year period before primary lumbar fusion, <65 years of age, and no enrollment in the database for 5 years before and 1 year after primary lumbar fusion. The primary outcome was spinal reoperation within 1, 3, and 5 years. Multivariable Cox regression was performed with age, sex, diabetes, heart disease, obesity, smoking status, osteoporosis, number of levels fused, use of posterior instrumentation, use of an interbody device, use of bone graft, and surgical approach as covariates.

RESULTS

Overall, 1,123 patients (63.4% female; 91.3% White; mean age, 76.8 ± 4.1 years) were included in the hip OA group and 8,893 patients (56.2% female; 91.3% White; mean age, 74.8 ± 4.9 years) were included in the control group. After multivariable analysis, patients with severe hip OA had significantly greater rates of revision surgery at 3 years (odds ratio [OR], 1.61; p < 0.001) and 5 years (OR, 1.87; p < 0.001) after the index lumbar fusion.

CONCLUSIONS

Patients with severe hip OA at the time of primary lumbar fusion had a significantly increased risk of spinal reoperation at 3 and 5 years postoperatively. These data provide further evidence to support performing THA prior to lumbar fusion in the unsettled debate regarding which surgery should be prioritized for patients with simultaneous degenerative diseases of the hip and lumbar spine.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Hip Osteoarthritis in Patients Undergoing Surgery for Severe Adult Spinal Deformity: Prevalence and Impact on Spine Surgery Outcomes

BACKGROUND

Hip osteoarthritis (OA) is common in patients with adult spinal deformity (ASD). Limited data exist on the prevalence of hip OA in patients with ASD, or on its impact on baseline and postoperative alignment and patient-reported outcome measures (PROMs). Therefore, this paper will assess the prevalence and impact of hip OA on alignment and PROMs.

METHODS

Patients with ASD who underwent L1-pelvis or longer fusions were included. Two independent reviewers graded hip OA with the Kellgren-Lawrence (KL) classification and stratified it by severity into non-severe (KL grade 1 or 2) and severe (KL grade 3 or 4). Radiographic parameters and PROMs were compared among 3 patient groups: Hip-Spine (hip KL grade 3 or 4 bilaterally), Unilateral (UL)-Hip (hip KL grade 3 or 4 unilaterally), or Spine (hip KL grade 1 or 2 bilaterally).

RESULTS

Of 520 patients with ASD who met inclusion criteria for an OA prevalence analysis, 34% (177 of 520) had severe bilateral hip OA and unilateral or bilateral hip arthroplasty had been performed in 8.7% (45 of 520). A subset of 165 patients had all data components and were examined: 68 Hip-Spine, 32 UL-Hip, and 65 Spine. Hip-Spine patients were older (67.9 ± 9.5 years, versus 59.6 ± 10.1 years for Spine and 65.8 ± 7.5 years for UL-Hip; p < 0.001) and had a higher frailty index (4.3 ± 2.6, versus 2.7 ± 2.0 for UL-Hip and 2.9 ± 2.0 for Spine; p < 0.001). At 1 year, the groups had similar lumbar lordosis, yet the Hip-Spine patients had a worse sagittal vertebral axis (SVA) measurement (45.9 ± 45.5 mm, versus 25.1 ± 37.1 mm for UL-Hip and 19.0 ± 39.3 mm for Spine; p = 0.001). Hip-Spine patients also had worse Veterans RAND-12 Physical Component Summary scores at baseline (25.7 ± 9.3, versus 28.7 ± 9.8 for UL-Hip and 31.3 ± 10.5 for Spine; p = 0.005) and 1 year postoperatively (34.5 ± 11.4, versus 40.3 ± 10.4 for UL-Hip and 40.1 ± 10.9 for Spine; p = 0.006).

CONCLUSIONS

This study of operatively treated ASD revealed that 1 in 3 patients had severe hip OA bilaterally. Such patients with severe bilateral hip OA had worse baseline SVA and PROMs that persisted 1 year following ASD surgery, despite correction of lordosis.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Impact of Hip and Knee Osteoarthritis on Full Body Sagittal Alignment and Compensation for Sagittal Spinal Deformity

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To investigate the effect of lower extremity osteoarthritis on sagittal alignment and compensatory mechanisms in adult spinal deformity (ASD).

BACKGROUND

Spine, hip, and knee pathologies often overlap in ASD patients. Limited data exists on how lower extremity osteoarthritis impacts sagittal alignment and compensatory mechanisms in ASD.

PATIENTS AND METHODS

In total, 527 preoperative ASD patients with full body radiographs were included. Patients were grouped by Kellgren-Lawrence grade of bilateral hips and knees and stratified by quartile of T1-Pelvic Angle (T1PA) severity into low-, mid-, high-, and severe-T1PA. Full-body alignment and compensation were compared across quartiles. Regression analysis examined the incremental impact of hip and knee osteoarthritis severity on compensation.

RESULTS

The mean T1PA for low-, mid-, high-, and severe-T1PA groups was 7.3°, 19.5°, 27.8°, and 41.6°, respectively. Mid-T1PA patients with severe hip osteoarthritis had an increased sagittal vertical axis and global sagittal alignment ( P <0.001). Increasing hip osteoarthritis severity resulted in decreased pelvic tilt ( P =0.001) and sacrofemoral angle ( P <0.001), but increased knee flexion ( P =0.012). Regression analysis revealed that with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis ( r2 =0.812). Hip osteoarthritis decreased compensation through sacrofemoral angle (β-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (β-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (β-coefficient=0.100).

CONCLUSIONS

For the same magnitude of spinal deformity, increased hip osteoarthritis severity was associated with worse truncal and full body alignment with posterior translation of the pelvis. Patients with severe hip and knee osteoarthritis exhibited decreased hip extension and pelvic tilt but increased knee flexion. This examines sagittal alignment and compensation in ASD patients with hip and knee arthritis and may help delineate whether hip and knee flexion is due to spinal deformity compensation or lower extremity osteoarthritis.

Impact of combined lumbar spine fusion and total hip arthroplasty on spine, pelvis, and hip kinematics during a sit to stand task

Lumbar fusion is a risk factor for hip dislocation following total hip arthroplasty (THA). The objective was to compare joint/segment angles during sit-stand-sit in participants that had a THA with and without a lumbar fusion. The secondary objective was to compare pain, physical function, disability, and quality of life. This cross-sectional study includes participants that had THA and lumbar fusion (THA-fusion; n = 12) or THA only (THA-only; n = 12). Participants completed sit-stand-sit trials. Joint/segment angles were measured using electromagnetic motion capture. Angle characteristics were determined using principal component analysis. Hierarchical linear models examined relationships between angle characteristics and groups. Pain, physical function, and disability were compared using Mann-Whitney U tests. Upper lumbar spine was more extended during sit-stand-sit in the THA-fusion group (b = 42.41, P = 0.04). The pelvis was more posteriorly and anteriorly tilted during down and end sit-stand-sit phases, respectively, in the THA-fusion group (b = 12.21, P = 0.03). There were no significant associations between group and other angles. THA-fusion group had worse pain, physical function, disability, and quality of life. Although differences in spine joint, pelvis segment, and hip joint angles existed, these findings are unlikely to account for the increased incidence of hip dislocation after total hip arthroplasty in patients that had spine fusion.

Novel subtype of coxitis knee associated with acetabular dysplasia of the hip: a case series

BACKGROUND

Multiple joint arthritis patterns require a comprehensive understanding to optimize patient management. This study aimed to present a patient cohort that deviated from known definitions of coxitis knee (CK), identifying and characterizing this atypical group.

METHODS

Patients undergoing both total hip arthroplasty and total knee arthroplasty between January 2008 and December 2018 were retrospectively reviewed. The patients were classified into a typical coxitis knee group (classic, long leg arthropathy, and windswept deformity) and an atypical coxitis knee group. Leg-length discrepancy, body mass index (BMI), and radiographic parameters of the groups were compared and analyzed.

RESULTS

A total of 31 patients were allocated to the typical coxitis knee group (n = 10), and atypical coxitis knee group (n = 21). In the atypical group, 27 hips were involved, of which 21 had acetabular dysplasia, 5 exhibited subchondral insufficiency fracture-like changes, and only 1 had classic osteoarthritis. Among the 27 knees undergoing total knee arthroplasty, 26 showed varus alignment, 1 was within the normal range, and none was valgus. Acetabular dysplasia involved ipsilateral (n = 1), contralateral (n = 14), and bilateral (n = 6) hips, showing atypical coxitis knee. Patients with acetabular dysplasia were more likely to exhibit atypical CK.

CONCLUSION

Most patients in the cohort displayed acetabular dysplasia and contralateral varus knees, constituting a pattern referred to as acetabular dysplasia-associated gonarthritis. Identifying this novel subtype may have important clinical implications for regions with high risk factors, where acetabular dysplasia and constitutional genu varum are prevalent.

Lumbar Level Significantly Influences Postoperative Global Sagittal Balance Following Pedicle Subtraction Osteotomy

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

The current evidence regarding how level of lumbar pedicle subtraction osteotomy (PSO) influences correction of sagittal alignment is limited. This study sought to investigate the relationship of lumbar level and segmental angular change (SAC) of PSO with the magnitude of global sagittal alignment correction.

METHODS

This study retrospectively evaluated 53 consecutive patients with adult spinal deformity who underwent lumbar PSO at a single institution. Radiographs were evaluated to quantify the effect of PSO on lumbar lordosis (LL), thoracic kyphosis (TK), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), T1-spinopelvic inclination (T1SPI), T1-pelvic alignment (TPA), and sagittal vertical axis (SVA).

RESULTS

Significant correlations were found between PSO SAC and the postoperative increase in LL (r = 0.316, P = .021) and PT (r = 0.352, P = .010), and a decrease in TPA (r = -0.324, P = .018). PSO level significantly correlated with change in T1SPI (r = -0.305, P = .026) and SVA (r = -0.406, P = .002), with more caudal PSO corresponding to a greater correction in sagittal balance. On multivariate analysis, more caudal PSO level independently predicted a greater reduction in T1SPI (β = -3.138, P = .009) and SVA (β = -29.030, P = .001), while larger PSO SAC (β = -0.375, P = .045) and a greater number of fusion levels (β = -1.427, P = .036) predicted a greater reduction in TPA.

CONCLUSION

This study identified a gain of approximately 3 degrees and 3 cm of correction for each level of PSO more caudal to L1. Additionally, a larger PSO SAC predicted greater improvement in TPA. While further investigation of these relationships is warranted, these findings may help guide preoperative PSO level selection.

Creating Consensus in the Definition of Spinopelvic Mobility

INTRODUCTION

The term "spinopelvic mobility" is most often applied to motion within the spinopelvic segment. It has also been used to describe changes in pelvic tilt between various functional positions, which is influenced by motion at the hip, knee, ankle and spinopelvic segment. In the interest of establishing a consistent language for spinopelvic mobility, we sought to clarify and simplify its definition to create consensus, improve communication, and increase consistency with research into the hip-spine relationship.

METHODS

A literature search was performed using the Medline (PubMed) library to identify all existing articles pertaining to spinopelvic mobility. We reported on the varying definitions of spinopelvic mobility including how different radiographic imaging techniques are used to define mobility.

RESULTS

The search term "spinopelvic mobility" returned a total of 72 articles. The frequency and context for the varying definitions of mobility were reported. 41 papers used standing and upright relaxed-seated radiographs without the use of extreme positioning, and 17 papers discussed the use of extreme positioning to define spinopelvic mobility.

DISCUSSION

Our review suggests that the definitions of spinopelvic mobility is not consistent in the majority of published literature. We suggest descriptions of spinopelvic mobility independently consider spinal motion, hip motion, and pelvic position, while recognizing and describing their interdependence.

Anteroposterior pelvic radiograph findings correlate with sagittal spinopelvic motion

It has been well documented in the arthroplasty literature that lumbar degenerative disc disease (DDD) contributes to abnormal spinopelvic motion. However, the relationship between the severity or pattern of hip osteoarthritis (OA) as measured on an anteroposterior (AP) pelvic view and spinopelvic biomechanics has not been well investigated. Therefore, the aim of the study is to examine the association between the severity and pattern of hip OA and spinopelvic motion. A retrospective chart review was conducted to identify patients undergoing primary total hip arthroplasty (THA). Plain AP pelvic radiographs were reviewed to document the morphological characteristic of osteoarthritic hips. Lateral spine-pelvis-hip sitting and standing plain radiographs were used to measure sacral slope (SS) and pelvic femoral angle (PFA) in each position. Lumbar disc spaces were measured to determine the presence of DDD. The difference between sitting and standing SS and PFA were calculated to quantify spinopelvic motion (ΔSS) and hip motion (ΔPFA), respectively. Univariate analysis and Pearson correlation were used to identify morphological hip characteristics associated with changes in spinopelvic motion. In total, 139 patients were included. Increased spinopelvic motion was observed in patients with loss of femoral head contour, cam deformity, and acetabular bone loss (all p < 0.05). Loss of hip motion was observed in patients with loss of femoral head contour, cam deformity, and acetabular bone loss (all p < 0.001). A decreased joint space was associated with a decreased ΔPFA (p = 0.040). The presence of disc space narrowing, disc space narrowing > two levels, and disc narrowing involving the L5-S1 segment were associated with decreased spinopelvic motion (all p < 0.05). Preoperative hip OA as assessed on an AP pelvic radiograph predicts spinopelvic motion. These data suggest that specific hip osteoarthritic morphological characteristics listed above alter spinopelvic motion to a greater extent than others.

Does Individualization of Cup Position Affect Prosthetic or Bone Impingement Following THA?

INTRODUCTION

Spinopelvic (SP) mobility patterns during postural changes affect three-dimensional acetabular component position, the incidence of prosthetic impingement, and total hip arthroplasty (THA) instability. Surgeons have commonly placed the acetabular component in a similar "safe zone" for most patients. Our purpose was to determine the incidence of bone and prosthetic impingement with various cup orientations and determine if a preoperative SP analysis with individualized cup orientation lessens impingement.

METHODS

A preoperative SP evaluation of 78 THA subjects was performed. Data was analyzed using a software program to determine the prevalence of prosthetic and bone impingement with a patient individualized cup orientation versus six commonly selected cup orientations. Impingement was correlated with known SP risk factors for dislocation.

RESULTS

Prosthetic impingement was least with the individualized choice of cup position (9%) vs. preselected cup positions (18 to 61%). The presence of bone impingement (33%) was similar in all groups and not affected by cup position. Factors associated with impingement in flexion were age, lumbar flexion, pelvic tilt (stand to flexed seated), and functional femoral stem anteversion. Risk factors in extension included standing pelvic tilt, standing SP tilt, lumbar flexion, pelvic rotation (supine to stand and stand to flexed seated), and functional femoral stem anteversion.

CONCLUSION

Prosthetic impingement is reduced with individualized cup positioning based on SP mobility patterns. Bone impingement occurred in one-third of patients and is a noteworthy consideration in preoperative THA planning. Known SP risk factors for THA instability correlated with the It dependspresence of prosthetic impingement in both flexion and extension.

Lack of correlation between hip osteoarthritis and anatomical spinopelvic parameters obtained in supine position on MRI

PURPOSE

Hip osteoarthritis (HOA) is known to have a multifactorial pathogenesis. Recent studies suggest that spinopelvic alignment may represent an important additional pathogenic abnormality resulting in HOA. This study aims to assess the correlation between spinopelvic parameters (pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and lumbar lordosis (LL)) obtained in the supine position on MRI and HOA, lateral center edge (LCE) angle, and patient reported back pain.

METHODS

Asymptomatic participants from the whole-body MRI cohort (FF4) from the cross-sectional case-control "Cooperative Health Research in the Region of Augsburg" study (KORA) were included. Whole-body MRI was performed in a standardized fashion in each case, on which hip osteoarthritis (HOA), anatomical spinopelvic parameters and lateral center edge angle were measured. Presence of back pain was assessed using a standardized questionnaire. Correlations were estimated by logistic regression models providing odds ratio.

RESULTS

Among 340 subjects (mean age 56.3 ± 9.3 years; 56.5% male), HOA was present in 89.1% (male: 87.0%, female: 91.7%, p = 0.17). The LCE angle was 30.0° ± 5.5 (men: 29.8° ± 5.9; women: 30.1° ± 5.1; p = 0.696). Mean PI was 54.0° ± 11.3°, PT was 13.7° ± 5.9°, SS was 40.3° ± 8.8° (significantly smaller in women p<0.05) and LL was 36.4° ± 9.6° (significantly greater in women p<0.05). None of the spinopelvic parameters correlated significantly with hip osteoarthritis or LCE angle. HOA was not correlated with back pain.

CONCLUSION

Spinopelvic parameters as measured in the supine position on MRI, do not correlate with hip osteoarthritis or lateral center edge angle.

Effect of Pelvic Sagittal Tilt and Axial Rotation on Functional Acetabular Orientation

Accurate and reproducible acetabular component positioning is among the most important technical factors affecting outcomes of total hip arthroplasty. Although several studies have investigated the influence of pelvic tilt and obliquity on functional acetabular anteversion, the effect of pelvic axial rotation has not yet been established. We analyzed a generic simulated pelvis created using preoperative full-body standing and sitting radiographs. A virtual acetabulum was placed in 144 different scenarios of acetabular anteversion and abduction angles. In each scenario, the effects of pelvic tilt and pelvic axial rotation on different combinations of acetabular orientations were assessed. The change in acetabular anteversion was 0.75° for each 1° of pelvic tilt and was most linear in abduction angles of 40°±45°. The change in acetabular anteversion was 0.8° for each 1° of pelvic axial rotation. Surgeons may consider adjusting acetabular anteversion in fixed axial pelvic deformities when the degree of deformity affects functional acetabular positioning, assessed from preoperative standing and sitting weight-bearing radiographs. [Orthopedics. 2023;46(1):e27-e30.].

Compensatory mechanisms in adult degenerative thoracolumbar spinal deformity - Radiographic patterns, their reversibility after corrective surgery, and the influence of pelvic morphology

Objective

Loss of lumbar lordosis (LL) in degenerative deformity activates spinal compensatory mechanisms to maintain neutral C7 sagittal vertical axis (C7SVA), such as an increase in pelvic tilt (PT) and decreased thoracic kyphosis (TK). We study the extent to which PT increase and TK reduction contribute to the compensation of pelvic incidence (PI)-LL mismatch.

Methods

A cohort of 43 adult patients with adult degenerative thoracolumbar deformity were included in this retrospective study. Radiographic spinopelvic measurements were obtained before and after corrective surgery. Pearson correlations were calculated.

Results

Preoperative PI-LL mismatch significantly correlated with an increase in PT and a decrease in TK in the whole cohort r = +0.66 (95% confidence interval [CI] 0.44-0.8) and r = -0.67 (95% CI - 0.81--0.47), respectively, at a relative rate of 0.37 (standard deviation [SD]: 0.07) and - 0.57 (SD: 0.09), respectively. In patients with low PI, only TK showed a significant correlation with PI-LL mismatch, r = -0.56 (95% CI - 0.8 to - 0.16), at a rate of - 0.57 (SD: 0.19). The high PI subgroup showed a significant correlation with PT, TK, and C7SVA, r = 0.62 (95% CI 0.26-0.82), r = -0.8 (95% CI - 0.9--0.58), and r = 0.71 (95% CI 0.41-0.87) at rates of 0.48 (SD: 0.11), -0.72 (SD: 0.12), and 0.62 (SD: 1.27).

Conclusions

Decreased TK represented a more consistent compensatory mechanism in patients with high and low PI when compared to an increase in PT. PI-LL mismatch induced more pronounced changes in TK than did PT in both subgroups. Patients with high PI relied more on increases in PT and a relative decrease in TK to compensate for PI-LL mismatch than patients with low PI.

Hip replacement improves lumbar flexibility and intervertebral disc height - a prospective observational investigation with standing and sitting assessment of patients undergoing total hip arthroplasty

PURPOSE

The pathogenic mechanism of the hip-spine syndrome is still poorly elucidated. Some studies have reported a reduction in low back pain after total hip arthroplasty (THA). However, the biomechanical mechanisms of THA acting on the lumbar spine are not well understood. The aim of the study is to evaluate the influence of THA on (1) the lumbar lordosis and the lumbar flexibility and (2) the lumbar intervertebral disc height.

METHODS

A total of 197 primary THA patients were prospectively enrolled. Pre- and post-operative biplanar stereoradiography was performed in standing and sitting positions. Spinopelvic parameters (lumbar lordosis (LL), pelvic tilt, sacral slope, pelvic incidence), sagittal spinal alignment (sagittal vertical axis, PI-LL mismatch (PI-LL)) and lumbar disc height index (DHI) for each segment (L1/2 to L5/S1) were evaluated. The difference between standing and sitting LL (∆LL = LL_standing - LL_sitting) was determined as lumbar flexibility. Osteochondrosis intervertebralis was graded according to Kellgren and Lawrence (0-4), and patients were assigned to subgroups (mild: 0-2; severe: 3-4).

RESULTS

Lumbar flexibility increased significantly after THA (pre: 22.04 ± 12.26°; post: 25.87 ± 12.26°; p < 0.001), due to significant alterations in LL in standing (pre: 51.3 ± 14.3°; post: 52.4 ± 13.8°; p < 0.001) and sitting (pre: 29.4 ± 15.4°; post: 26.7 ± 15.4°; p = 0.01). ∆LL increased significantly in both subgroups stratified by osteochondrosis (pre/post: ΔLL_mild: 25.4 (± 11.8)/29.4 ± 12.0°; p < 0.001; ΔLL_severe: 17.5 (± 11.4)/21.0 ± 10.9°; p = 0.003). The DHI increased significantly from pre-operatively to post-operatively in each lumbar segment. PI-LL mismatch decreased significantly after THA (pre: 3.5°; post: 1.4°; p < 0.001).

CONCLUSION

The impact of THA on the spinopelvic complex was demonstrated by significantly improved lumbar flexibility and a gain in post-operative disc height. These results illustrate the close interaction between the pelvis and the vertebral column. The investigation provides new insights into the biomechanical patterns influencing the hip-spine syndrome.

Study on the Influencing Factors of Osteoarthritis in Southern China

Background

Osteoarthritis (OA) is a common chronic disease with numerous and interacting influencing factors, and current inadequate patient perceptions and behaviors in access to care contribute to the difficulties in the diagnosis, treatment, and management of osteoarthritis.

Objective

The purpose of this study was to investigate the influencing factors of osteoarthritis (OA) in a southern Chinese population and to provide a scientific basis for the prevention and treatment of OA.

Methods

A 1 : 2 matched case-control study was used to select 160 patients with OA from three hospitals in southern China as a case group. Three hundred and twenty cases of the same sex and similar age (within ± 2 years) were selected as the control group, and relevant data were collected for univariate and multivariate conditional logistic regression analysis.

Results

There were no significant differences between the two groups of participants in terms of age, sex, and education (P > 0.05). Logistic regression statistical analysis showed that genetic factors (OR = 4.52, 95% CI = 1.56-7.83), body mass index (OR = 2.57, 95% CI = 1.16-5.84), alcohol consumption (OR = 3.81, 95% CI = 1.53-5.87), and a history of external joint limb injury (OR = 3.37, 95% CI = 1.67-5.24) would increase the risk of OA. In contrast, eating more fresh vegetables (OR = 0.08, 95% CI = 0.03-0.31), more fresh fruits (OR = 0.34, 95% CI = 0.12-0.96), more soy products (OR = 0.11, 95% CI = 0.04-0.45), and exposure to sunlight (OR = 0.31, 95% CI = 0.14-0.71) would reduce the OA risk of OA.

Conclusion

Obesity, alcohol consumption, and a history of joint trauma all increase the risk of OA in a southern Chinese population, whereas a diet rich in fresh vegetables, fresh fruit, soy products, and sun exposure would reduce the risk of OA. In the future, we should focus on improving patients' awareness of medical care and developing their self-management skills, improving GPs' treatment skills, improving negative attitudes of both doctors and patients, and promoting positive patient care.

Sagittal alignment in patients with flexion contracture of the hip before and after total hip arthroplasty

INTRODUCTION

In hip osteoarthritis, hip flexion contracture can severely alter the patient's alignment, and, therefore, affect the patient's quality of life (QOL). Hip contracture is not well-studied, partly because of the difficulties of its diagnosis. The aim of this study was to propose a quantitative definition of hip flexion contracture, and to analyse sagittal alignment in these patients compared to non-contracture ones, before and 12 months after total hip arthroplasty (THA).

MATERIALS AND METHODS

Consecutive patients with hip arthrosis and an indication for THA were included (N = 123). Sagittal full-body radiographs were acquired in free standing position and in extension. QOL questionnaires were administered before and after surgery. Spinopelvic parameters were measured, including the pelvic-femur angle (PFA). Patients with low pelvic incidence (< 45°) were included in the hip contracture group if PFA > 5°, or PFA > -5° when pelvic incidence ≥ 45°.

RESULTS

29% of patients were in the hip flexion contracture group, and they showed lower pelvic tilt than the no-contracture group (p < 0.001), larger lumbar lordosis (LL) and smaller PI-LL (p < 0.001), as well as a forward position of the head. 16% of patients still had hip contracture 12-months postop. Contracture patients showed higher QOL scores after surgery.

CONCLUSIONS

The proposed method to diagnose hip contracture group allowed to define a group of patients who showed a specific pattern of sagittal spinopelvic alignment. These patients improved their alignment and quality of life postoperatively, but their hip mobility was not always restored. Diagnosing these patients is a first step toward the development of more specific surgical approaches, aiming to improve their surgical outcome.

Does surgery change pelvic tilt? : an investigation in patients with osteoarthritis of the hip, dysplasia, and femoroacetabular impingement

AIMS

Pelvic tilt is believed to affect the symptomology of osteoarthritis (OA) of the hip by alterations in joint movement, dysplasia of the hip by modification of acetabular cover, and femoroacetabular impingement by influencing the impingement-free range of motion. While the apparent role of pelvic tilt in hip pathology has been reported, the exact effects of many forms of treatment on pelvic tilt are unknown. The primary aim of this study was to investigate the effects of surgery on pelvic tilt in these three groups of patients.

METHODS

The demographic, radiological, and outcome data for all patients operated on by the senior author between October 2016 and January 2020 were identified from a prospective registry, and all those who underwent surgery with a primary diagnosis of OA, dysplasia, or femoroacetabular impingement were considered for inclusion. Pelvic tilt was assessed on anteroposterior (AP) standing radiographs using the pre- and postoperative pubic symphysis to sacroiliac joint (PS-SI) distance, and the outcomes were assessed with the Hip Outcome Score (HOS), International Hip Outcome Tool (iHOT-12), and Harris Hip Score (HHS).

RESULTS

The linear regression model revealed a significant negative predictive association between the standing pre- and postoperative PS-SI distances for all three groups of patients (all p < 0.001). There was a significant improvement in all three outcome measures between the pre- and postoperative values (p < 0.05).

CONCLUSION

There is a statistically significant decrease in pelvic tilt after surgery in patients with OA of the hip, dysplasia, and femoroacetabular impingement. These results confirm that surgery significantly alters the pelvic orientation. Pelvic tilt significantly decreased after total hip arthroplasty, periacetabular osteotomy, and arthroscopy/surgical hip dislocation. The impact of surgery on pelvic tilt should be considered within the therapeutic plan in order to optimize pelvic orientation in these patients.Cite this article: Bone Joint J 2022;104-B(9):1025-1031.

Risk Factors for Progressive Spinal Sagittal Imbalance in the Short-Term Course after Total Hip Arthroplasty: A 3 Year Follow-Up Study of Female Patients

Total hip arthroplasty (THA) for patients with hip osteoarthritis improves hip flexion contracture, subsequently improving spinal sagittal balance. However, in some cases, spinal sagittal imbalance develops in the course after THA, and its risk factors remain unknown. We aimed to investigate the risk factors of progressive spinal sagittal imbalance after THA. This retrospective cohort study of a prospectively maintained database included female patients aged ≥50 years who underwent THA. Before performing THA, we obtained each patient’s anthropometric and muscle strength measurements and whole-spine radiographs. Three years postoperatively, patients underwent whole-spine radiography to examine changes in the spinal sagittal balance. Patients were assigned into groups on the basis of their preoperative and 3 year postoperative sagittal vertical axis (SVA) values. Patients with 3 year postoperative SVA values ≥40 mm with an increase ≥30 mm were categorized into the imbalance group; the other patients were categorized into the non-imbalance group. Of 103 patients, 11 (10.7%) were in the imbalance group. In multiple logistic regression analysis, preoperative weak abdominal trunk muscle strength (ATMS) (p = 0.007) and small sacral slope (SS) (p = 0.005) were significant risk factors for progressive spinal sagittal imbalance. In conclusion, risk factors for progressive spinal sagittal imbalance after THA were weak preoperative ATMS and small SS.

Impact of the hip joint mobility on whole-body sagittal alignment: prospective analysis in case with hip arthroplasty

PURPOSE

To clarify the impact of restriction of hip extension on radiographic whole-body sagittal alignment with using postoperative changes of radiographical parameters for hip osteoarthritis.

METHODS

We prospectively enrolled 68 patients with hip osteoarthritis scheduled for arthroplasty. Variables included manual examination of hip range of motion (H-ROM) and radiographic whole-body sagittal alignment parameters including sagittal vertical axis (SVA), center of acoustic meatus and femoral head offset (CAM-HA), thoracic kyphosis (TK), lumbar lordosis, sacral slope (SS), and knee flexion angle (KF). We divided patients with preoperative hip extension angle < 0 into the extension restriction (ER) + group and ≥ 0 into the ER- group. Differences in H-ROM, radiographic parameters between groups and postoperative changes were comparatively analyzed.

RESULTS

Fifty-seven patients (The ER + group included 28 patients and the ER- group included 29 patients.) were available for the analysis. Pre-/postoperative H-ROM were 99.7 ± 24.9/118.1 ± 16.0 degrees (p < .01). Greater increases in SVA (5.4 ± 3.4 vs 3.4 ± 2.8 cm, p = .02) and in CAM-HA (3.9 ± 3.9 vs 2.8 ± 3.4 cm, p =  013) were found in the ER + group versus ER- group. Postoperatively, the ER + group showed an increase in TK (pre-/postoperative: 35.2 ± 9.7/37.4 ± 8.8 degrees, p = .04) and decreases in SS (36.5 ± 9.6/33.7 ± 9.9 degrees, p < .01) and KF (9.5 ± 7.0/6.9 ± 6.0 degrees, p = .02). Postoperative changes in radiographic parameters in the ER- group were not significant.

CONCLUSION

Patients with restriction of hip extension showed global spine imbalance, and significant changes in TK, SS, and KF were observed after arthroplasty. The presence of hip joint disorder and H-ROM restriction must be considered when evaluating spinopelvic alignment and whole-body sagittal alignment.

Timing of Total Hip Arthroplasty Affects Lumbar Spinal Fusion Outcomes

STUDY DESIGN

This is a retrospective cohort study of consecutive patients undergoing lumbar spinal fusion (LSF) within the PearlDiver Humana research database from 2010 to 2018.

OBJECTIVE

The aim of this study was to determine if timing of total hip arthroplasty (THA) affects LSF outcomes.

SUMMARY OF BACKGROUND DATA

In patients with both spine and hip pathology, outcomes of THA have been shown to be affected by the timing of THA relative to LSF. However, few studies have assessed postoperative outcomes following LSF in this clinical scenario.

MATERIALS AND METHODS

A national database was queried for patients undergoing lumbar fusion and divided into 4 groups: (1) those who underwent LSF without THA (No THA); (2) those who underwent THA at least 2 years before LSF (>2 Prior THA); (3) those who underwent THA in the 2 years before LSF (0-2 Prior THA); and (4) those who underwent THA after LSF (THA After). We assessed lumbar-specific outcomes, including pseudarthrosis, revision, mechanical failure, and adjacent segment disease (ASD); as well as systemic complications. Controlling for age, sex, and Charlson comorbidity index, complication rates between all groups were assessed using univariate and multivariate logistic regression analysis. Post hoc comparisons were performed using the Fisher exact test with Bonferroni correction to account for multiple pairwise comparisons, resulting in an adjusted threshold for statistical significance of P<0.007.

RESULTS

When compared with the no THA group, those in the THA After group had a higher rate of ASD on multivariate analysis [adjusted odds ratio: 1.53, 95% confidence interval: 1.20-1.94, P<0.001]. When compared with all patients who underwent THA before LSF, patients who underwent THA after LSF had an increased risk of ASD (adjusted odds ratio: 3.80, 95% confidence interval: 2.21-6.98, P<0.001).

CONCLUSIONS

Patients who undergo THA after LSF have an increased rate of lumbar-related complications both when compared with patients who do not undergo THA and when compared with patients who undergo THA before LSF.

Spinopelvic mobility is influenced by pre-existing contralateral hip arthroplasty: a matched-pair analysis in patients undergoing hip replacement

Background

Spinopelvic mobility gained increased attention as a contributing factor for total hip arthroplasty (THA) instability. However, it is unknown how a pre-existing THA affects spinopelvic mobility. Therefore, a propensity-score-matched analysis of primary THA patients comparing the individual segments of spinopelvic mobility between patients with pre-existing THA and no-existing THA was conducted. Consequently, the study aimed to discuss (1) whether patients with a pre-existing THA have altered spinopelvic mobility compared to the control group and (2) if spinopelvic mobility changes after THA.

Methods

A prospective observational study enrolled 197 elective primary THA patients, including N = 44 patients with a pre-existing unilateral THA. Using propensity-score matching adapted for age, sex, and BMI, N = 44 patients without a pre-existing THA were determined. The patients received stereoradiography in standing and relaxed sitting position pre- and postoperatively. Assessed parameters were lumbar lordosis (LL), pelvic tilt (PT), and pelvic femoral angle (PFA). Key parameters of the spinopelvic mobility were defined as lumbar flexibility (∆LL = LL_standing − LL_sitting), pelvic mobility (∆PT = PT_standing − PT_sitting) and hip motion (∆PFA = PFA_standing − PFA_sitting). Pelvic mobility was classified as stiff (∆PT < 10°), normal (∆PT ≥ 10°–30°) and hypermobile (∆PT > 30°). The Wilcoxon rank sum test for dependent samples was used.

Results

Pelvic mobility was significantly increased in the pre-existing THA group (∆PT 18.2° ± 10.7) compared to the control group (∆PT 7.7° ± 8.0; p < 0.001) preoperatively and postoperatively (pre-existing: 22.2° ± 9.3; control: 17.0° ± 9.2, p = 0.022). Lumbar flexibility was significantly increased in the pre-existing THA group (∆LL 21.6° ± 11.8) compared to the control group (∆LL 12.4° ± 7.8; p < 0.001) preoperatively and postoperatively (pre-existing: 25.7° ± 11.0; control: 19.0° ± 10.2; p = 0.011). The contribution of stiff pelvic mobility is distinctly smaller in the pre-existing THA group (25%) than in the control group (75%) preoperatively.

Conclusions

Pre-existing THA is associated with significantly enhanced pelvic mobility and lumbar flexibility. Accordingly, we identified the patients without a pre-existing THA as risk candidates with higher likelihood for pathological spinopelvic mobility. This information will assist arthroplasty surgeons in deciding which THA candidates require preoperative radiological screening for pathologic spinopelvic mobility.

Level of evidence

Level II prospective cohort study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-02945-5.

SPINOPELVIC MOBILITY IN PATIENTS WITH HIP OSTEOARTHRITIS AND TOTAL HIP ARTHROPLASTY INDICATION

ABSTRACT Introduction: Reduction of spinopelvic mobility is associated with an increased dislocation of total hip arthroplasty (THA). Objective: To assess 1) spinopelvic mobility in patients with primary hip osteoarthritis and THA indication and 2) the influence of hip flexion contracture on spinopelvic mobility. Methods: Thirty adult patients with primary hip osteoarthritis and THA indication were evaluated using radiographic parameters (pelvic incidence, pelvic tilt, sacral slope, lumbar flexibility, and spinopelvic mobility). Results: Spinopelvic mobility ranged from 6.90 a 54.50° (mean 32.79 ± 11.42) and the group of patients with hip flexion contracture had higher mobility. Spinopelvic mobility was correlated with pelvic tilt as well as with lumbar flexibility. Conclusion: Around 13.4% of patients had spinopelvic mobility under 20° , indicating reduced spinopelvic mobility and risk of THA dislocation. Level of Evidence III, Retrospective Comparative Study.

Preoperative spinopelvic hypermobility resolves following total hip arthroplasty

AIMS

Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA.

METHODS

This study investigated patients with preoperative posterior hypermobility, defined as a change in sacral slope (SS) from standing to sitting (ΔSS_stand-sit) ≥ 30°. Radiological spinopelvic parameters, including SS, pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative imaging, and at six weeks and a minimum of one year postoperatively. The severity of bilateral hip osteoarthritis (OA) was graded using Kellgren-Lawrence criteria.

RESULTS

A total of 136 patients were identified as having preoperative spinopelvic hypermobility. At one year after THA, 95% (129/136) of patients were no longer categorized as hypermobile on standing and sitting radiographs (ΔSS_stand-sit < 30°). Mean ΔSS_stand-sit decreased from 36.4° (SD 5.1°) at baseline to 21.4° (SD 6.6°) at one year (p < 0.001). Mean SS_seated increased from baseline (11.4° (SD 8.8°)) to one year after THA by 11.5° (SD 7.4°) (p < 0.001), which correlates to an 8.5° (SD 5.5°) mean decrease in seated functional cup anteversion. Contralateral hip OA was the only radiological predictor of hypermobility persisting at one year after surgery. The overall reoperation rate was 1.5%.

CONCLUSION

Spinopelvic hypermobility was found to resolve in the majority (95%) of patients one year after THA. The increase in SS_seated was clinically significant, suggesting that current target recommendations for the hypermobile patient (decreased anteversion and inclination) should be revisited. Cite this article: Bone Joint J 2021;103-B(12):1766-1773.

Neglected reactive arthritis complicated by bilateral hip and temporomandibular joints ankylosis after a suspected tetanus infection: a case report

Background

Reactive arthritis had been reported to occur after various vaccinations, including the tetanus toxoid vaccine; here, we report a case of ankylosing arthropathy suggested to be a complication of missed neglected reactive arthritis after tetanus infection.

Case presentation

A healthy 20-year-old woman presented with subtrochanteric right femoral fracture; imaging studies showed bilateral ankylosed hip, kyphoscoliosis, bilateral fused temporomandibular joints, and normal sacroiliac joints bilaterally. Laboratory investigations for a rheumatic or autoimmune disease were all within normal ranges. Detailed history revealed admission of the patient to an ICU unit (1 year before the trauma) for a month as she was diagnosed as having tetanus infection, after which she was unable to walk or feed herself. At the final follow-up, the patient started walking with a moderate limb after having a series of surgeries including femoral fracture fixation, temporomandibular joint excision arthroplasty, and bilateral total hip arthroplasty.

Conclusion

Unusual complications after tetanus infection can occur in the form of joint ankylosis, which could be presented after prolonged immobilization possibly due to improper management of reactive arthritis.

Correlation of Acetabular Anteversion and Thoracic Kyphosis Postoperatively with Proximal Junctional Failure in Adult Spinal Deformity Fused to Pelvis

Objectives

To investigate whether the immediate thoracic kyphosis (TK) and acetabular anteversion (AA) postoperatively are correlated with proximal junctional failure (PJF) in adult spinal deformity (ASD) patients underwent surgical treatment.

Methods

This is a retrospective study. Following institutional ethics approval, a total of 57 patients (49 Female, eight Male) with ASD underwent surgery fused to sacroiliac bone (S1, S2, or ilium) from March 2014 to January 2019 were included. All of those patients were followed up for at least 2 years. Demographic, radiographic and surgical data were recorded. The maximum range of flexion motion (F‐ROM) and extension motion (E‐ROM) actively of hip joints was measured and recorded at pre‐ and postoperation. The sum of F‐ROM and E‐ROM was defined as the range of hip motion (H‐ROM). Receiver operating characteristic (ROC) curve analysis was used to obtain the cut off value of parameters for PJF. A Kaplan–Meier curve and log‐rank test were used to analyze the differences in PJF‐free survival.

Results

In all, 14 patients developed PJF during follow‐up. Comparisons between patients with and without PJF showed significant differences in immediate TK (P < 0.001) and AA (P = 0.027) postoperatively. ROC curve analysis determined an optimal threshold of 13° for immediate AA postoperatively (sensitivity = 74.3%, specificity = 85.7%, area under the ROC curve [AUC] = 0.806, 95% CI [0.686–0.926]). Nineteen patients with post‐AA ≤13° were assigned into the observational group, and 38 patients with post‐AA >13° were being as the control group. Patients in the observational group had smaller H‐ROM (P = 0.016) and F‐ROM (P < 0.001), but much larger E‐ROM (P < 0.001). There were 10 patients showing PJF in the observational group and four in the control group (10/9 vs 4/34, P < 0.001). PJF‐free survival time significantly decreased in the observational group (P = 0.001, log‐rank test). Furthermore, patients in the observational group had much larger TK (post‐TK, P = 0.015). The optimal threshold for post‐TK (sensitivity = 85.7%, specificity = 76.7%; AUC = 0.823, 95% CI [0.672–0.974]) was 28.1° after the ROC curve was analyzed. In the observational group, those patients with post‐TK ≥28.1° had significantly higher incidence of PJF (9/2 vs 1/7, P < 0.001) than those with post‐TK < 28.1°. Moreover, PJF‐free survival time in those patients significantly decreased (P = 0.001, log‐rank test).

Conclusions

ASD patients with acetabular anteversion of ≤13° at early postoperation may suffer significantly restricted hip motion and much higher incidence of PJF during follow‐up, moreover, in those patients, postoperative TK ≥28.1° would be a significant risk factor for PJF developing.

The Hip-Spine Challenge

➤

The proper diagnosis and treatment of patients with concurrent hip and spine pathological processes can be challenging because of the substantial overlap in symptomatology.

➤

There is no consensus on which pathological condition should be addressed first.

➤

Factors such as advanced spinal degeneration, deformity, and prior fusion alter the biomechanics of the spinopelvic unit. Attention should be paid to recognizing these issues during the work-up for a total hip arthroplasty as they can result in an increased risk of dislocation.

➤

In patients with concurrent spine and hip degeneration, the surgeon must pay close attention to appropriate implant positioning and have consideration for implants with enhanced stability to minimize the risk of dislocation.

➤

A proper understanding of sagittal balance and restoration of this balance is integral to improving patient outcomes following spinal surgery.

➤

The advent of new imaging modalities, increased awareness of spinopelvic mobility, as well as a better understanding of sagittal alignment will hopefully improve our treatment of patients with hip-spine syndrome.

Spine-Pelvis-Hip Alignments in Degenerative Spinal Deformity Patients and Associated Procedure of One-Stage Long-Fusion with Multiple-Level PLIF or Apical-Vertebra Three Column Osteotomy-a Clinical and Radiographic Analysis Study

OBJECTIVE

To explore the spine-pelvis-hip alignments in degenerative spinal deformity (DSD) patients, and compare the outcomes in the procedure of long-fusion with posterior lumbar inter-body fusion (PLIF) or single-level three-column osteotomy (STO) at lower lumbar level (LLL, L3 -S1 ) and thoracolumbar levels (TLL, T10 -L2 ) for those patients.

METHODS

This is a retrospective study. Following institutional ethics approval, a total of 83 patients (Female, 67; Male, 16) with DSD underwent long-fusion with PLIF or STO surgery between March 2015 and December 2017 were reviewed. All of those patients were assigned into LLL and TLL groups. The average age at surgery was 65.2 years (SD, 8.1). Demographic (age, gender, BMI, and comorbidities), radiographs (both coronal and sagittal parameters) and health-related quality of life (HRQOL) assessments were documented. The radiographic parameters and HRQOL-related measurements at pre- and post-operation were compared with paired-samples t test, and those variables in the two groups were analyzed using an independent-sample t test. The relationships between pelvic incidence (PI) and other sagittal parameters were investigated with Pearson correlation analysis. The Pearson χ2 or Fisher's exact was carried out for comparison of gender, incidence of comorbidities and post-operative complications.

RESULTS

There were 53 and 30 patients in the LLL and TLL groups respectively. Those spino-pelvic radiographic parameters had significant improvements after surgeries (P < 0.001). The patients in the two group with different pre-operative thoracolumbar kyphosis (TLK, P = 0.003), PI (P = 0.02), and mismatch of PI minus lumbar lordosis (PI-LL, P = 0.01) had comparable post-operative radiographic parameters except PI (P = 0.04) and pelvic-femur angle (PFA, P = 0.02). Comparing the changes of those spine-pelvic-hip data during surgeries, the corrections of TLK in TLL group were significant larger (P = 0.004). Pearson correlation analysis showed that there were negative relationship between PI and TLK (r = -0.302, P = 0.005), positive relationship between PI and LL (r = 0.261, P = 0.016) at pre-operation. Those patients underwent the surgical procedure that long-segment instrumentation and fusion with STO would have higher incidence of complications involving longer operative timing (P = 0.018), more blood loss (P < 0.001), revision surgery (P = 0.008), and cerebrospinal fluid leakage (P = 0.001). All the HRQOL scores significantly improved at final follow-up (P < 0.001), with no difference of intra-group.

CONCLUSION

Patients suffered de-novo scoliosis or hyper-kyphosis with low PI would be vulnerable to significant thoracolumbar degeneration, and have more changes of spine-pelvis-hip data after long-fusion surgery, however, those with high PI would be closed to significant lumbar degeneration. Although spine-pelvis-hip alignments in DSD patients can be restored effectively after long-fusion with PLIF or STO, the incidence of complications in patients underwent STO was significant higher than that in patients performed multi-level PLIF.

High Thoracic Kyphosis and Backward Trunk Inclination Angles in the Single-Leg Standing Position Associate With Medial Elbow Injuries in Youth Baseball Players: A Cross-Sectional Study

CONTEXT

Baseball pitching is a coordinated movement involving the spine. A previous study indicated that increased thoracic kyphosis angle in a standing position was a risk factor for medial elbow injuries in youth baseball players. However, spinal alignments in single-leg standing and their relationships with medial elbow injuries, scapular alignment, or hip joint range of motion are unclear.

OBJECTIVE

To examine the difference in spinal alignment between standing and single-leg standing positions in youth baseball players and analyze their relationship with elbow injuries, scapular alignment, or hip joint range of motion.

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

There were 51 youth baseball players with medial epicondylar fragmentation (medial elbow injury group) and 102 healthy youth baseball players (control group).

MAIN OUTCOME MEASURES

Thoracic kyphosis, lumbar lordosis, and trunk inclination angles during standing and single-leg standing, forward scapular posture, and hip joint range of motion.

RESULTS

In the single-leg standing position, the thoracic kyphosis and backward trunk inclination angles were significantly higher in the medial elbow injury group than in the control group (P = .016 and P = .046, respectively). In the standing position, no significant difference was observed between both groups. The thoracic kyphosis angle in single-leg standing was positively correlated with the bilateral forward scapular posture in the medial elbow injury (P = .008 and P < .001 on the throwing and nonthrowing sides, respectively) and control (P = .010 and P = .032 on the throwing and nonthrowing sides, respectively) groups.

CONCLUSIONS

High thoracic kyphosis and backward trunk inclination angles are characteristics during single-leg standing in youth baseball players with medial elbow injuries. Spinal alignment measurement in single-leg standing may be useful for identifying youth baseball players who are at risk for sustaining medial elbow injury.

Functional Anatomy of the Hip Joint

BACKGROUND

The functional anatomy of the osteoarthritic hip joint in the sagittal plane has not been defined. The purpose of this study was to define the functional anatomy of the hip using clinical and radiographic analyses.

METHODS

320 hips had preoperative standing and sitting lateral spine-pelvis-hip X-rays. Radiographic pelvic measurements were pelvic incidence (PI) and sacral slope (SS), and hip measurements were anteinclination (AI) and pelvic femoral angle (PFA). Pelvic tilt (PT) was calculated as PI-SS. A triangle model was created from the clinical data that illustrates the functional motion of the hip during postural changes from standing to sitting.

RESULTS

Pelvic motion was coordinated with hip motion, even with spinopelvic imbalance and stiffness. Pelvic motion (ΔSS) varied for all 5 types of imbalance, but pelvic motion (ΔSS) and acetabular motion (ΔAI) changed with a 1:1 ratio and inversely with femoral motion (ΔPFA) with a 1:1 ratio. The triangle model showed similar results with ΔSS, ΔPT, and ΔAI changing in a 1:1:1 ratio, and femur motion inversely changing with a 1:1 ratio.

CONCLUSION

The functional anatomy of the hip joint can be visually illustrated using a triangle model. Pelvic angles SS, PT, and AI change in unison, whereas femoral motion (ΔPFA) changes inversely with pelvic motion (ΔSS) in a 1:1 ratio. This coordinated mobility explains the limitations of the Lewinnek safe zone, which include only the acetabulum.

Obesity Alters Spinopelvic Alignment Changes From Standing to Relaxed Sitting: the Influence of the Soft-tissue Envelope

Background

Changes in spinopelvic and lower extremity alignment between standing and relaxed sitting have important clinical implications with regard to stability of total hip arthroplasty. This study aimed to analyze the effect of body mass index (BMI) on lumbopelvic alignment and motion at the hip joint.

Methods

A retrospective review of patients who underwent full-body stereoradiographs in standing and relaxed sitting for total hip arthroplasty planning was conducted. Spinopelvic parameters measured included spinopelvic tilt (SPT), pelvic incidence (PI), lumbar lordosis (LL), PI minus LL (PI-LL), proximal femoral shaft angle (PFSA), and standing-to-sitting hip range of motion. Propensity score matching controlled for age, gender, PI, and hip ostoarthritis grade. Patients were stratified into normal (NORMAL; BMI, 18.5-24.9), overweight (OW; 25.0-29.9), and obese (OB; 30.0-34.9) groups. Alignment parameters were compared using one-way analysis of variance.

Results

There were 84 patients in each group after propensity score matching. Standing alignment between BMI groups was similar for all parameters (P > .05) except for PFSA (P < .001). Significant differences were noted for sitting alignment between patients who are NORMAL, OW, and OB in: SPT (P = .007), PI-LL (P = .018), and LL (P = .029). PFSA between groups was not significantly different (P > .05). Significant differences were found for sitting-to-standing alignment across groups in PFSA change (P < .001), SPT change (P = .006), PI-LL change (P = .005), LL change (P = .037), and hip flexion (P < .001).

Conclusions

Significant differences in sitting and standing-to-sitting change in lumbopelvic alignment based on BMI suggest obese patients recruit more posterior spinopelvic tilt when sitting to compensate for soft-tissue impingement that occurs anterior to the hip joint and limiting hip flexion.