Previous lumbar spine fusion increases the risk of dislocation following total hip arthroplasty in patients with hip-spine syndrome: a systematic review and meta-analysis.

BACKGROUND: With life expectancy on the rise, there has been an increase in patients with concomitant degenerative hip and spine pathology, defined as hip-spine syndrome (HSS). Patients affected by HSS may require both total hip arthroplasty (THA) and lumbar spinal fusion (LSF), although there is a paucity of data regarding how the sequential timing of these procedures may influence clinical outcomes. This study aims to compare complications and spinopelvic parameters in patients with HSS who underwent either LSF first or THA first. METHODS: A systematic search of PubMed and Scopus was conducted for randomized and nonrandomized studies investigating complications and spinopelvic parameters in patients with HSS who had undergone THA and LSF. The Methodological Index for Non-Randomized Studies (MINORS) tool was utilized to assess the risk of bias in included studies. Relevant outcomes were pooled for meta-analysis. RESULTS: Eleven articles were included in this study. There was a significantly higher THA dislocation rate in patients who had undergone LSF first compared to those who had THA first (OR: 3.17, 95% CI 1.23-8.15, P = 0.02). No significant difference was found in terms of THA aseptic loosening (OR: 0.86; 95% CI 0.32-2.32, p = 0.77) and revision rate (OR: 1.18, 95% CI: 0.53-2.62) between these two groups. Individuals who received THA only showed a significantly lower risk of hip dislocation (OR: 0.14, 95% CI: 0.08-0.25, P < 0.00001) and THA revision (OR: 0.22, 95% CI: 0.14-0.36, P < 0.00001) compared to patients with a previous LSF. CONCLUSIONS: In HSS patients who underwent both LSF and THA, those who received LSF first displayed an increased risk of hip dislocation after subsequent THA. Additionally, the relative risks of dislocation and revision rate appeared significantly lower in patients who had undergone THA only when compared to THA patients with a history of previous LSF. Due to the impact of LSF on spinopelvic biomechanics, caution must be exercised when performing THA in individuals with instrumented spines. PROSPERO ID: CRD42023412447. LEVEL OF EVIDENCE: LL.

Association between cup orientation and low back pain after total hip arthroplasty in patients with osteonecrosis of the femoral head.

BACKGROUND: Postoperative low back pain (LBP) following total hip arthroplasty (THA) is classified as secondary hip-spine syndrome. The purpose of this study was to explore the correlations between cup orientation of THA and postoperative LBP in patients with osteonecrosis of the femoral head (ONFH). METHODS: A retrospective cohort study included 364 ONFH patients who underwent bilateral THA between January 2011 and December 2020. Among them, 53 patients (14.6%) experienced postoperative LBP at the end of follow-up and were designated as pain group (PG). A control group (CG) consisting of 106 patients with similar age, sex, and body mass index (BMI) to those in the PG was selected. Postoperative LBP in the PG was assessed using the visual analogue scale (VAS). Demographic data, clinical information, and radiographic criteria were evaluated as potential predictors of LBP. RESULTS: Patients in PG (mean age, 47.3 years [range, 27 to 75 years]; 42 [79%] male) had a mean VAS score of 4.6 (range, 1 to 9) compared with 0 for the patients in CG (mean age, 47.6 years [range, 19 to 77 years]; 84 [79%] male). There were no significant differences in clinical data between the two groups (p > 0.05). Preoperative radiographic variables also showed no significant differences between the PG and CG (p > 0.05). However, the postoperative inclination, anteversion, and standing ante-inclination (AI) were significantly lower in the PG compared to the CG, whereas the sitting and standing sacral slope (SS) were significantly higher (p < 0.05). Moreover, the variations in standing AI, standing and sitting pelvic tilt (PT) were significantly lower in the PG compared to the CG, while the variations in standing and sitting SS and lumbar lordosis (LL) were significantly higher (p < 0.05). The variation in standing AI in the PG showed a significantly correlation with the variation of standing SS, standing PT, and LL (p < 0.05). CONCLUSION: Postoperative LBP in ONFH patients after bilateral THA is significantly associated with the intraoperative cup orientation. The variation in standing AI is correlated with the variations in standing SS, standing PT, and LL, potentially contributing to the development of postoperative LBP.

How Do Spinal Parameters Change in Patients Who Have Improvement of Low Back Pain After Total Hip Arthroplasty? A Propensity Score-Matched Cohort Study.

BACKGROUND: Many studies have demonstrated that low back pain (LBP) improves after total hip arthroplasty (THA). However, the mechanism underlying this improvement remains unclear. We aimed to investigate changes in the spinal parameters of patients who had LBP improvement after THA to elucidate the mechanism of LBP improvement. METHODS: We included 261 patients who underwent primary THA between December 2015 and June 2021 and had a preoperative visual analog scale score of ≥ 2 for LBP. The patients were classified into the LBP-improved or LBP-continued groups based on the visual analog scale for LBP at 1 year after THA. Preoperative and postoperative changes in the coronal and sagittal spinal parameters were compared between the 2 groups after propensity score matching for age, sex, body mass index, and preoperative spinal parameters. RESULTS: A total of 161 patients (61.7%) were classified into the LBP-improved group. After 85 patients in both groups were matched, the LBP-improved group showed significant differences in spinal parameter changes, which were a higher lumbar lordosis (LL) (P = .04) and lower sagittal vertical axis (SVA) (P = .02) and pelvic incidence (PI) minus LL (PI-LL) (P = .01) postoperatively, whereas the LBP-continued group showed worsened changes in LL and SVA and PI-LL mismatch. CONCLUSION: Patients who had LBP improvement after THA had significant differences in spinal parameter changes in LL, SVA, and PI-LL. These spinal parameters may be the key factors in the mechanism of LBP improvement after THA.

Preoperative Abnormal Posture Improves After Total Knee Arthroplasty: Knee-Hip-Spine Syndrome.

BACKGROUND: Spinal, pelvic, and lower extremity alignment is crucial for maintaining a healthy body posture. However, with aging, this posture becomes challenging to maintain due to muscle weakness and skeletal degeneration. Osteoarthritis (OA) of the hip and knee can also lead to abnormal posture, known as hip-spine and knee-spine syndrome. Total knee arthroplasty (TKA) can help relieve pain and improve lower extremity alignment. This may also improve abnormal posture, such as in knee-hip-spine syndrome. However, the condition of the contralateral knee may affect this improvement. This study evaluated the effects of TKA on clinical outcomes and radiographic body posture. METHODS: Patients scheduled for primary one-sided TKA were divided into 2 groups: the unilateral group comprised patients who had contralateral knee OA conditions. The bilateral group included patients who had prior contralateral TKA. Knee range of motion, the Knee Injury and Osteoarthritis Outcome Score, radiographic lateral femorotibial angle, hip and knee flexion angles, and sagittal vertical axis while standing were measured 24 months after TKA. RESULTS: Both groups showed improved knee extension, the Knee Injury and Osteoarthritis Outcome Score, and radiographical femorotibial angle and hip and knee flexion angles 24 months after TKA. The sagittal vertical axis also improved 6 months after TKA in both groups and was maintained in the bilateral group, while it deteriorated again in the unilateral group 24 months after TKA. CONCLUSIONS: A TKA can improve abnormal body posture due to knee OA as in knee-hip-spine syndrome. However, the condition of a contralateral knee can affect TKA outcomes. LEVEL OF EVIDENCE: Level III; prospective case-control study.

Outcomes and complications of Total Hip Arthroplasty in patients with a pre-existing pathologic spine-hip relation. A systematic review of the literature.

BACKGROUND: There has been a growing interest in pathologic spine-hip relations (PSHR) in current literature, with the aim of reducing the risk of prosthetic impingement, dislocation, and edge loading in total hip arthroplasty (THA). The primary objective of this review is to determine the effect of different PSHR on primary THA outcomes and complication profile. The secondary objective is to stratify the risk of different subgroups of PSHR patients. METHODS: A systematic review of the literature was performed in accordance with PRISMA guidelines. Randomised controlled trials, comparative cohort studies and case-control studies comparing outcomes and complication rates of primary THA in patients with and without a PSHR (spinal fusion; degenerative spinal conditions determining stiff spine and/or spinal misalignment) were included. The quality of the included studies and the risk of bias were assessed. The revision rate, complications, and clinical and radiological data were analysed. Complications included: aseptic loosening (AL), periprosthetic joint infections (PJI), hip dislocations and periprosthetic fractures (PF). RESULTS: Fifteen articles were included with 3.306.342 THAs. The mean follow-up (FU) was 31.4 ± 21.7 months. The population was divided into three subgroups: spinal fusion patients (48.315 THAs); non-fused patients with spinal stiffness (106.110 THAs); non-fused patients with normal spines (3.151.917 THAs). A statistically significant risk stratification was observed about dislocation rate (5.98 ± 6.9% SF, 3.0 ± 1.9% non-SF Stiff and 2.26 ± 1.4% non-SF; p = 0.028). Similarly, about THA revision rate, a statistically significant risk stratification was also observed (7.3 ± 6.8% SF, 6.4 ± 3.1% non-SF Stiff and 2.7 ± 1.7% non-SF; p = 0.020). No statistically significant difference was observed when analysing AL, PJI and PF. CONCLUSION: A statistically significant risk stratification of dislocation and revision rate was observed in the different PHSR, as theorised by the Bordeaux classification. Fused patients present a higher risk, degenerated and/or stiff spine an intermediate risk and mobile spines a lower risk profile. A standardised approach to THA candidate patients must consider the possible PSHR to improve clinical outcomes and reduce adverse events of THA.

Does Order of Operation Matter in Patients Who Have Concomitant Hip and Spine Pathology?

BACKGROUND: In patients, who have coexisting lumbar spine and degenerative hip disease, there remains uncertainty regarding whether hip or spine surgery should be performed first. We hypothesized that undergoing total hip arthroplasty (THA) would protect against subsequent lumbar spine surgery (LSS) in patients who have 'hip-spine syndrome.' METHODS: A retrospective cohort study was performed from 2013 to 2021 on patients who had radiographically-confirmed hip osteoarthritis and degenerative lumbar spine pathology, evaluated separately in spine and arthroplasty clinics prior to surgical intervention. Included patients ultimately underwent THA and/or LSS. The primary outcome was survivorship free of LSS or THA after the other was initially performed. RESULTS: Of 256 patients, 206 (80.5%) underwent THA first. Only 14 of 206 (6.8%) who underwent THA required subsequent LSS, while 31 of 50 (62%) who underwent LSS required subsequent THA, (P < .001). At 5 years, there was 93.9% survivorship-free of LSS in the THA first group, compared to 44.7% survivorship-free of subsequent THA in the LSS group. Multivariate analyses showed that patients who had THA first had lower odds of undergoing subsequent surgery (odds ratio [OR]: 0.61, CI: 0.52-0.70, P < .001) compared to those who underwent LSS first. Additionally, those who have higher initial Kellgren-Lawrence grade hip osteoarthritis had lower odds (OR: 0.94, CI: 0.89-0.99, P = .04), and those who have progressive neurologic deficits (OR: 2.64, CI: 1.89-3.7, P < .001) and neurogenic claudication (OR: 1.15, CI: 1.06-1.24, P = .001) had increased odds of undergoing subsequent LSS. CONCLUSION: Patients with 'hip-spine syndrome' may receive more initial benefit from undergoing THA, potentially reducing the subsequent need for LSS. The exceptions were those patients who had lower-severity hip osteoarthritis and symptoms of major spinal stenosis.

Spine or Hip First? Outcomes in Patients Undergoing Sequential Lumbar Spine or Hip Surgery.

BACKGROUND: Lumbar spine pathology frequently coexists in patients who have hip arthrosis. There is controversy on whether lumbar or hip pathology should be first addressed. The purpose of this study was to evaluate the outcomes of sequential lumbar spine (LSP) or hip arthroplasty (THA). METHODS: Using a large national database from 2010 to 2020, we reviewed the records of 241,279 patients who had concurrent hip arthritis and lumbar spine disease defined as spinal stenosis, lumbar radiculopathy, or degenerative disc disease. During the study period, 6,458 (2.7%) patients with concurrent hip/spine disease underwent sequential operative treatment of either the hip joint or lumbar spine within 2 years. The rates of subsequent surgery in either the hip or the spine, opioid requirements, and rates of hip dislocation were determined and analyzed using compared Chi-squared analyses. RESULTS: Patients undergoing THA first had lower risk of subsequent spinal procedure compared to patients who had spinal procedures first (5.7 versus 23.7%, P < .001). This disparity was maintained up to 5 years (P < .001). Opioid requirements at 1 year were highest in patients who underwent spinal procedures only (836 pills/patient) compared to any other group THA only (566 pills/patient), LSP and then THA (564 pills/patient), THA and LSP (586 pills/patient). Also, THA following LSP was associated with significantly higher rates of dislocation compared to patients undergoing THA first (3.2 versus 1.9%, P < .001). CONCLUSION: Total hip arthroplasty first in patients who have concurrent spine disease was associated with lower risk of subsequent surgery, opioid requirement, and risk of postoperative instability compared to patients having lumbar procedure first.

Validity and application of Doiguchi's pelvic tilt measurement method.

BACKGROUND: The validity of Doiguchi's pelvic tilt measurement method has not been proven. The objective in our study was to validate the method. METHODS: Our investigation included 73 total hip arthroplasties (THAs) performed using our cup placement procedure from July 2020 to November 2021. Pelvic tilt formed by the pubic symphysis and sacral promontory (PTPS) in supine and lateral positions was calculated by two methods (the Doiguchi method and the digital reconstructed radiograph (DRR) method using a 3D computer templating system) based on the transverse and longitudinal diameters of the pelvic ring measured immediately before THA. RESULTS: There was a strong/moderate correlation in the values of PTPS between the Doiguchi and DRR methods. However, the value of PTPS calculated by the Doiguchi method was significantly lower than that calculated by DRR, and there was a partially direct match. On the other hand, there was no significant difference in the value of PT change from supine to lateral position between the Doiguchi and DRR methods. The PT changes based on both methods were strongly correlated, and the PT change calculated by the Doiguchi method was almost identical to that calculated by the DRR method. CONCLUSIONS: Doiguchi's pelvic tilt measurement method was validated for the first time. These results demonstrated that the ratio of the transverse and longitudinal diameters of the pelvic ring was an important factor defining the change in pelvic tilt. The slope in the linear function of the Doiguchi method was found to be almost the correct value, although the intercept of the linear function exhibited individual differences.

Hip joint stress distribution changes depending on three-dimensional pelvic orientation: Finite-element analysis.

BACKGROUND: Pelvis experiences changes in its orientation due to the alignment of the hip joint and spine, and its orientation might affect both joints. Pelvic tilt on the sagittal plane has been widely discussed; however, the pelvis is oriented also on the coronal and horizontal planes. This study aimed to examine how stress distribution on intact hip joint changes under the three-dimensional pelvic orientation. METHODS: Computed tomography data of five patients with unilateral pelvic girdle were analyzed. Thirteen models were evaluated by the MECHANICAL FINDER: neutral position at 0°; 10° and 20° anterior and posterior pelvic tilt; 10° and 20° pelvic hike and drop; 10° and 20° pelvic forward and backward rotation. Stress assessment was performed in four parts of the acetabulum: anterosuperior, posterosuperior, posteroinferior, and central parts. RESULTS: Compared with the neutral position, the mean value of the equivalent stress and maximum principal stress in the anterosuperior part significantly increased by 1.51 times and 1.57 times at 20° posterior tilt, respectively. The maximum principal stress in the anterosuperior part significantly increased by 1.44 times at 20° hike. A significant increase of 1.45 times was found in the maximum principal stress in the anterosuperior part at 20° forward rotation. CONCLUSIONS: Local stress accumulated in the anterosuperior acetabulum at the posterior pelvic tilt, pelvic hike, and pelvic forward rotation, which might lead to hip overload. The effect of posterior pelvic tilt appears to be greater for the hip joint than at the pelvic hike or forward rotation.

Current Concepts in Diagnosis and Management of Patients Undergoing Total Hip Replacement with Concurrent Disorders of Spinopelvic Anatomy: A Narrative Review.

Despite the high success rate of primary total hip replacement (THR), a significant early revision rate remains, which is largely attributed to instability and dislocations. Despite the implants being placed according to the safe zone philosophy of Lewinnek, occurrence of THR dislocation is not an uncommon complication. Large diagnostic and computational model studies have shown variability in patients' mobility based on the individual anatomic and functional relationship of the hip-pelvis-spine complex. The absolute and relative position of hip replacement components changes throughout motion of the patient's body. In the case of spinopelvic pathology such as spine stiffness, the system reaches abnormal positional states, as shown with computerized models. The clinical result of such pathologic hip positioning is edge loading, implant impingement, or even joint dislocation. To prevent such complications, surgeons must change the dogma of single correct implant positioning and take into account patients' individualized anatomy and function. It is essential to broaden the standard diagnostics and their anatomical interpretation, and correct the pre-operative surgical planning. The need for correct and personalized implant placement pushes forward the development and adaptation of novel technologies in THR, such as robotics. In this current concepts narrative review, we simplify the spinopelvic biomechanics and pathoanatomy, the relevant anatomical terminology, and the diagnosis and management algorithms most commonly used today.

Sacrospinous and sacrotuberous ligaments influence in pelvis kinematics.

The alteration in mechanical properties of posterior pelvis ligaments may cause a biased pelvis deformation which, in turn, may contribute to hip and spine instability and malfunction. Here, the effect of different mechanical properties of ligaments on lumbopelvic deformation is analyzed via the finite element method. First, the improved finite element model was validated using experimental data from previous studies and then used to calculate the sensitivity of lumbopelvic deformation to changes in ligament mechanical properties, load magnitude, and unilateral ligament resection. The deformation of the lumbopelvic complex relative to a given load was predominant in the medial plane. The effect of unilateral resection on deformation appeared to be counterintuitive, suggesting that ligaments have the ability to redistribute load and that they play an important role in the mechanics of the lumbopelvic complex.

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.

Preoperative Factors Associated With Low Back Pain Improvement After Total Hip Arthroplasty in a Japanese Population.

BACKGROUND: Spinal disorders and low back pain (LBP) have been associated with worse clinical outcomes of total hip arthroplasty (THA). It is essential to identify spinal factors associated with post-THA LBP improvement. Therefore, we aimed to determine the proportion of patients with improved LBP after THA and to identify the preoperative spinal factors associated with LBP improvement. METHODS: We included 151 patients who underwent primary THA between December 2015 and December 2019 and had a preoperative visual analog scale score for LBP of ≥2. The patients were classified into the LBP improved or LBP continued group based on a visual analog scale score for LBP at 1 year after THA. Preoperative spinal parameters were compared between the 2 groups. RESULTS: Ninety-five patients (62.9%) were classified into the LBP improved group. Among the coronal spinal parameters, the Cobb angle was significantly lower in the LBP improved group. Among the sagittal spinal parameters, the LBP continued group showed a significantly more posteriorly titled pelvis, lower lumbar lordosis, greater sagittal vertical axis, and greater pelvic incidence minus lumbar lordosis mismatch, indicating a sagittal spinal imbalance. Logistic regression analysis found that preoperative factors associated with LBP improvement after THA had a low Cobb angle and high anterior pelvic plane angle (anteriorly tilted pelvis). CONCLUSION: Among patients with LBP before THA, 62.9% had improved LBP. Sagittal spinal imbalance and high Cobb angle were the key spinal factors associated with persistent LBP. Our findings suggest that hip surgeons should evaluate spinal alignment before THA in patients with LBP.

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 = LLstanding - LLsitting) 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: ΔLLmild: 25.4 (± 11.8)/29.4 ± 12.0°; p < 0.001; ΔLLsevere: 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.

Investigating sagittal spinal alignment, low back pain, and clinical outcomes after total hip arthroplasty for lumbar hyperlordosis: a retrospective study.

INTRODUCTION: Hip-spine syndrome, wherein flexion deformity of the hip might exaggerate normal lumbar lordosis (LL), was first described in 1983. It could result in subluxation of the posterior facets and cause low back pain (LBP). However, the clinical outcomes of total hip arthroplasty (THA) and spinal alignment changes in patients with lumbar hyperlordosis (hyper LL) remain unknown. We aimed to clarify the proportion of patients with hyper LL before THA and compare pre- and post-operative sagittal spinal alignment, LBP, and clinical outcomes between patients with hyper LL and those with normal LL. MATERIALS AND METHODS: We investigated 278 patients who underwent primary THA between December 2015 and December 2019. Spine radiographs in the standing position were examined preoperatively and 1 year postoperatively. Patients with hyper LL were defined as having a pelvic incidence (PI) minus LL of < - 9° preoperatively. The control group included age- and sex-matched patients with normal LL, defined by a PI minus LL of - 9° to 9°. Clinical outcomes were evaluated using the visual analogue scale (VAS) for LBP, Harris hip score (HHS), Oxford hip score (OHS), and University of California, Los Angeles (UCLA) activity score. RESULTS: Thirty-eight patients (13.7%) had hyper LL, and they exhibited a lower pelvic tilt, lower sagittal vertical axis, and greater sigmoid curvature than did the controls. Evaluation of changes in the spinal alignment after surgery showed that the pelvis tilted more posteriorly, and LL decreased more in the hyper LL group than in the control group. Pre- and post-operative VAS for LBP, HHS, OHS, and UCLA activity scores were not significantly different between the two groups. CONCLUSION: Hyper LL in patients with hip osteoarthritis had no adverse effects on LBP and the clinical outcomes of THA. Hyper LL may partially result from a flexible and adaptable lumbo-pelvic structure.

Spine Fusions, Yoga Instructors, and Hip Fractures: The Role of Dual Mobility in Primary Total Hip Arthroplasty.

BACKGROUND: Despite the increased use of dual mobility (DM) in primary total hip arthroplasty (THA), debate exists regarding the indications for its use. No specific algorithm exists to guide this decision-making process. Therefore, the purpose of this article is to summarize the currently available literature regarding the use of DM in primary THA and provide evidence-based guidelines based on specific patient populations and risk factors for instability. METHODS: We reviewed the current literature for studies evaluating risk factors for dislocation in primary THA, as well as the clinical use and results of DM in primary THA. Based on the strength of the literature, we discuss the use of DM in specific patient populations. We provide a decision-making algorithm to determine whether a patient may be indicated for DM in primary THA. RESULTS: Surgeons should consider preoperative patient demographics, risk factors for instability (eg, significant hip-spine issues), type of procedure to be performed (eg, conversion arthroplasty), and indications for surgery (eg, THA for femoral neck fracture). Based on this algorithmic assessment, DM may be warranted in the primary THA setting if a patient's combined risk reaches an established threshold based on the literature. CONCLUSION: This evidence-based algorithm may help guide current practice in the use of DM in primary THA. We advocate the continued judicious use of DM in hip arthroplasty. Longer term studies are needed in order to evaluate the durability of DM, as well as any complications related to the DM articulation.

Sagittal spinal-pelvic alignment in patients with Crowe type IV developmental dysplasia of the hip.

BACKGROUND: The impact of high dislocated dysplastic hips on spinal-pelvic alignment has not been well described. This study aims to evaluate compensatory spinal radiographic changes and presence of back pain in patients with Crowe type IV developmental dysplasia of the hip (DDH). METHODS: An observational study was conducted from July 2016 to December 2017, and 49 consecutive patients with Crowe IV DDH were enrolled. Forty-nine sex- and age-matched asymptomatic healthy adults were recruited as the controls. The sacral slope (SS), lumbar lordosis (LL), spino-sacral angle (SSA), C7 tilt (C7T), and sagittal vertical axis (SVA [C7]) were measured on lateral whole spine radiographs. The presence of low back pain and visual analogue scale (VAS) scores were recorded. RESULTS: The patients with Crowe IV DDH showed significantly greater SS (47.5 ± 7.5° vs. 40.4 ± 6.7°, p < 0.05), LL (- 63.7 ± 9.2° vs. - 53.3 ± 11.5°, P < 0.05), SSA (141.8° ± 7.2° vs. 130.6 ± 7.9°, p < 0.05), C7T (93.9 ± 3.6° vs. 91.1 ± 3.7°, P < 0.05), and lower SVA(C7) (- 16 mm[- 95-45] vs. 6.4 mm[- 52-47], p < 0.05) compared to the controls. The patients with bilateral Crowe IV DDH also exhibited larger SS, LL, SSA, and C7T and a smaller SVA (C7) than those with unilateral Crowe IV DDH. Sixty-three percent of the patients with Crowe IV DDH reported low back pain. CONCLUSION: The patients with Crowe IV DDH exhibited abnormal spinal-pelvic alignment characterized by anterior pelvic tilt, lumbar hyperlordosis, and a backward-leaning trunk. Bilateral Crowe IV DDH had a greater impact on spinal-pelvic alignment than unilateral Crowe IV DDH.

Degeneration of three or more lumbar discs significantly decreases lumbar spine/hip ROM ratio during position change from standing to sitting in AVN patients before THA.

BACKGROUND: Limitations in the lumbar spine movement reduce lumbar vertebral motion and affect spinopelvic kinematics. We studied the influence of lumbar intervertebral disc degeneration on spinofemoral movement, from standing to sitting, in patients undergoing total hip arthroplasty (THA). METHODS: Of 138 consecutive patients scheduled for THA due to unilateral avascular necrosis (AVN) of the femoral head, those with ≥3 discs with University of California at Los Angeles (UCLA) disc degeneration score > 1 were defined as the lumbar degenerative disc disease (LDD) group, and the remaining patients constituted d the control group. Full body anteroposterior and lateral EOS images in the standing and sitting positions were obtained. Pelvic incidence (PI), L1 slope (L1 s), lumbar lordosis angle (LL), pelvic tilt (PT), sacral slope (SS), femoral slope (Fs), sagittal vertical axis (SVA), hip flexion, lumbar spine flexion, and total spinofemoral flexion were measured on the images and compared between groups. RESULTS: No significant between-group differences were observed in the height, weight, body mass index, AVN staging, or PI, SS, and Fs on standing. The LDD group included more females and older patients, had 5° lesser LL, 5° greater PT, and larger SVA. From standing to sitting, the PI remained constant in both groups. Total spinofemoral flexion was 7° less, lumbar spine flexion 16° less, L1 slope change 6° less, and SS change 8° less, and hip flexion was 7° more in the LDD than in the control group. The spine/hip flexion ratio was significantly lower in the LDD group (0.3 versus 0.7; p < 0.001). On regression analysis, the LDD group (p < 0.001) and older age (p = 0.048) but not sex, weight, or height were significant univariate predictors of decreased spine/hip ratio. CONCLUSIONS: Patients with LDD leant more forward and had a larger pelvis posterior tilt angle on standing and a decreased lumbar spine/hip flexion ratio, with more hip joint flexion, on sitting, to compensate for reduced lumbar spine flexion. Surgeons should be aware that elderly patients with multiple LDD have significantly different spinofemoral movements and increased risk of posterior dislocation post-THA. Preoperative patient identification, intraoperative surgical technique modification, and individualized rehabilitation protocols are necessary.

Sagittal spino-pelvic alignment in rapidly destructive coxarthrosis.

PURPOSE: To investigate the sagittal spino-pelvic alignment (SSPA) in patients with rapidly destructive coxarthrosis (RDC). METHODS: SSPA was investigated in 44 patients with RDC and 70 patients with hip osteoarthritis (HOA). The study included only female patients over the age of 70 years because epidemiological reports indicate that RDC most commonly occurs in this group of patients. The SSPA parameters that were analyzed included lumbar lordosis (LL), lumbar range of motion (ΔLL), sacral slope (SS), pelvic incidence (PI), and pelvic tilt (PT). The pelvic inclination angle (PIA) in the supine position and the change in the PIA from the supine to the standing position (ΔPIA) were measured using anteroposterior pelvic radiographs. The values of these parameters were compared between the two groups. The levels of the SRS-Schwab classification modifiers were used to investigate the degree of sagittal malalignment. RESULTS: The RDC group showed significant lower LL, ΔLL and SS values, and significantly higher PT and ΔPIA values than the HOA group (P < 0.01). With regard to the sagittal modifiers in the SRS-Schwab classifications of the patients, the PI-LL and PT levels of the RDC group were significantly worse than those in the HOA group (P < 0.01). CONCLUSIONS: The present study suggests that the static factors of a reduction in the lumbar lordotic angle and greater posterior pelvic tilt, the dynamic factors of small ΔLL values and large ΔPIA values and the complex interaction of these two types of factors, may play important roles in the development of RDC.

Spinopelvic parameter changes and low back pain improvement due to femoral neck anteversion in patients with severe unilateral primary hip osteoarthritis undergoing total hip replacement.

PURPOSE: The study of the interrelation between hip and spine disorders is gaining increasing importance in the last years, but the link between Hip Osteoarthritis (HOA) and Low Back Pain (LBP) remains still unclear. Aim of the study is to assess the relationship between Femoral Neck Anteversion (FNA), LBP, and spinopelvic parameters in patients undergoing Total Hip Replacement (THR) for unilateral severe primary HOA. MATERIALS AND METHODS: 91 patients were recruited. Inclusion criteria were: grade 5 or 6 unilateral HOA, according to Turmezei, and Harris Hip score (HHS) <60. Exclusion criteria were: secondary hip osteoarthritis (dysplasia of the hip, rheumatoid arthritis, and ankylosing spondylitis); previous surgery of the spine, hip or knee; scoliosis with a Cobb angle greater than 10°; spondylolisthesis; history of spine fractures; previous bone tuberculosis or any spine infections; any contraindications to CT; BMI >30. Patients were divided into two homogeneous Groups according to the presence (Group-A) or not of concomitant LBP (Group-B). All patients underwent preoperatively a hip CT scan to evaluate FNA, Acetabular Anteversion (AA), and Combined Anteversion (CA = FNA + AA). ΔFNA, ΔAA and ΔCA were calculated as the differences between the arthritic hip and the normal hip angles in each Group. Full spinal X-rays in upstanding position were performed before (baseline) and 6 months after THR (follow-up) to calculate spinopelvic parameters. The health-related quality of life (HRQoL) was evaluated at baseline and at follow-up using Visual Analogue Scale (VAS), HHS, Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RM), and Short-Form Health Survey (SF-36). The intra-group and inter-group variability were assessed using, respectively, paired and unpaired t tests. At baseline, the association between HRQoL scores and ΔFNA, ΔAA, and ΔCA was analysed by the Pearson correlation test. RESULTS: At baseline, in Group-A, there was a significant difference between arthritic FNA and normal hip FNA, while no differences were found in AA between the two hips. A close correlation was observed between ΔFNA and Spine-VAS (r = 0.788), ODI (r = 0.824), and RM (r = 0.775). In Group-B, there was not a significant difference in FNA and AA between the two hips. At recruitment, in Group-A patients, we recorded a higher LL, SS, PI, SVA(C7), and a lower PT and T1-SPI compared with Group-B subjects. Six months after THR, in Group-A, an improvement of all clinical scores was recorded, as well as, a significant reduction of SS, LL, T1PA, and SVA(C7) and an increment of PT. In Group-B, at follow-up, an improvement of HHS, Hip-VAS, and SF-36 was recorded, while the changes in spinopelvic parameters were not significant. CONCLUSIONS: Patients with concomitant unilateral HOA and LBP showed a marked anteverted FNA in the arthritic hip and a spinopelvic misalignment. After THR, a relief of both hip and low back pain and a change in spinopelvic parameters is observed.