The lordosis distribution index (LDI) describes distribution of lumbar lordosis, measured as the % of lower lumbar lordosis (L4-S1) compared to global lordosis (L1-S1) with normal value 50–50%. Maldistributed LDI is associated with higher revision in short lumbar fusions, 4 vertebrae1. We hypothesise maldistributed LDI is also associated with mechanical failure in longer fusions.

Retrospective review of 29 consecutive ASD patients, aged 55+, undergoing long lumbar fusion, 4 levels, with >3-years follow-up. LDI, pelvic incidence (PI) and sagittal vertical axis (SVA) were measured on pre- and post-op whole spine standing X-rays (Fig A and B). Patients were categorized according to their pelvic incidence (PI) and postoperative LDI: Normal (LDI 50 80), Hypolordotic (LDI < 50), or Hyperlordotic (LDI > 80) and assessed for failure rate compared to normal LDI and PI <60.

Mean follow-up 4.5 years. 19 patients had mechanical failures including junctional failure and metalware fracture. PI >60o was associated with higher mechanical failure rates (Chi^2 p<0.05). Hypolordotic LDI was associated with 82% mechanical failure (Chi^2 p<0.001), Hyperlordotic 88% mechanical failure (Chi^2 p<0.001) and Normal 8% mechanical failure (Table 1).

Maldistributed LDI, whether Hyperlordotic or Hypolordotic, correlated with 10× greater mechanical failure rate compared to Normal LDI in long fusions. LDI is a useful measurement that should be considered, especially in high PI patients.

This paper is a theoretical and experimental study of the processes involved in the development of curvature of the spine which we have come to call scoliosis. Reasons are advanced why the term scoliosis in its modern meaning may be misleading and an alternative title of Rotational Lordosis is suggested. It is admitted that it is more cumbersome, but I maintain that it is more accurately descriptive of the deformity under discussion and differentiates it from other curvatures which are produced differently but at present all of which come under the heading of scoliosis. I am conscious that many gaps still remain unfilled, especially the important but unexplained problem of the nature of the growth disturbance. If we could solve this we would be near to a solution of one of the most bizarre, mysterious and crippling deformities with which we are faced

The pelvic girdle and spine vertebral column work as a long chain influenced by pelvic tilt. Spinal deformities or other musculoskeletal conditions may cause patients to compensate with excessive pelvic tilt, producing alterations in the degree of lumbar lordosis and subsequently causing pain. The objective of this study is to assess the effect of open and closed chain anterior or posterior pelvic tilt on lumbar spine kinematics using an in vitro cadaveric spine model.

Three human cadaveric spines with intact pelvis were suspended with the skull fixed in a metal frame. Optotrak 3D motion system tracked real-time coordinates of pin markers on the lumbar spine. A force-torque digital gage applied consistent force to standardize the acetabular or sacral axis’ anterior and posterior pelvic tilt during simulated open and closed chain movements, respectively.

In closed chain PPT, significant differences in relative intervertebral compression existed between L1/L2 [-2.54 mm] and L5/S1 [-11.84 mm], and between L3/L4 [-2.78 mm] and L5/S1 [-11.84 mm] [p <.05]. In closed chain APT, significant differences in relative intervertebral decompression existed between spinal levels L1/L2 [2.87mm] and L5/S1[24.48 mm] and between L3/L4 [2.94 mm] and L5/S1 [24.48 mm] [p <.05]. In open chain APT, significant differences in relative intervertebral decompression existed between spinal levels L4/L5 [1.53mm] and L5/S1 [25.14 mm] and between L2/L3 [1.68 mm] and L5/S1 [25.14 mm] [p<.05 for both]. Displacement during closed chain PPT was significantly greater than during open chain PPT, whereas APT showed no significant differences.

In PPT, open chain pelvic tilts did not produce as much lumbar intervertebral displacement compared to closed chain. In contrast, APT saw no significant differences between open and closed chain. Additionally, results illustrate the increase in lumbar lordosis during APT and the loss of lordosis during PPT.

Centre Hospitalo-Universitaire de Bordeaux, Service de Pathologie du la Colonne Vertébrale, Bordeaux, France.

Assessment of cervical lordosis using a standardised digital acquisition procedure in the normal population

Three independent reviewers measured static lordosis. The EOS¯ system, which utilises low dose radiation and provides reliable standardized digital 2D acquisition with 3D reconstruction was employed. Measurements were carried out twice by every examiner on two different occasions.

Cohort of the general public of 180 subjects divided into 4 groups (both sexes individually, age less than 40 and greater than 50 individually). None had any previous history of spinal disorders or sagittal imbalance. General cervical lordosis (C2 to C7) as well as upper and lower cervical lordosis were assessed.

Cervical lordosis in the general population has a very wide range in both sexes. Overall cervical lordosis was 37 degrees. Lower cervical lordosis (superior endplate of C4 to inferior endplate of C7) demonstrated an average of 16 degrees, and upper cervical lordosis was found to be 21 degrees.

No particular age group or sex was more prone to having lesser/greater lordosis.

Current literature is sparse and provides large ranges, different standards and variable methods for assessing standard cervical lordosis. Overall cervical lordosis is very variable amongst the sexes and age groups. We provide a standard set of values which help to provide the spinal surgeon with values to aim for when seeking to restore cervical lordosis.

Surgery for degenerative lumbar spondylolisthesis may entail both decompression and fusion. The knee-chest position facilitates the decompression, but fixation in this position risks fusion in kyphosis. This can be avoided by intra-operative re-positioning to the prone position. The aim of this study was to quantify the restoration of lordosis achieved by intra-operative repositioning and to assess the clinical and radiological outcome.

A total of forty consecutive patients with degenerative lumbar spondylolisthesis and stenosis were treated by posterior decompression and interbody fusion with pedicle screw fixation. The screw insertion, decompression and interbody grafting were performed with the patient in the knee-chest position. The patient was then re-positioned to the fully prone position for fusion. Sagittal plane angles were measured pre-, intra- and post-operatively. Clinical assessment was performed using SF-36 scores and visual analogue scores for back and leg pain.

The sagittal plane angle increased from median 16.0 degrees pre-operatively to 23.1 degrees post-operatively (p<0.01) and this was maintained at the last follow-up (mean 21 months). The SF-36 scores improved for 7 out of 8 domains and the physical score improved from 29% to 40% (p<0.05). The mean pain scores improved significantly from 7.5 to 3.8 for back pain and from 7.6 to 3.7 for leg pain (p<0.001).

Lumbar spondylolisthesis was found to be associated with a reduction of normal lumbar lordosis and the knee-chest position exacerbates this loss of lordosis. Intra-operative repositioning restored lordosis to greater than the pre-operative angle and was associated with a good clinical outcome.

Background: Back pain is a common complaint in the Western World with a sedentary lifestyle contributing to its recurrence. The aim of this study was to establish differences in lumbar and thoracic posture after a period of unsupported sitting between subjects with a history of back pain but no current symptoms (BP) and those without a history of back pain (NBP).

Method: Twenty subjects (10 BP and 10 NBP group) fulfilling specific inclusion criteria were recruited. Ethical approval was obtained from the Institutions Ethical Committee. Following placement of markers on the vertebrae L5, T12 and C7, subjects sat unsupported on a plinth following standardisation of hip and knee position. A digital image (sagittal view) was taken at 1, 5 and 10 minutes. Spinal curvature was measured using Matlab, two-dimensional analysis system. Repeated measures ANOVA with Post Hoc analysis were calculated to determine the differences between groups and time points.

Results: The NBP group demonstrated no difference in thoracic or lumbar curvature at 1, 5 and 10 minutes. The BP group showed a statistically significant difference in lumbar spine curvature between one and ten minutes (p=0.006). No significant differences in thoracic curvature in BP group were found (F =.524 p = 0.601).

Conclusion: This study showed that subjects with BP demonstrate a change in lumbar curvature following a period of unsupported sitting compared to NBP group. The thoracic kyphosis in both group remained unchanged. Further studies investigating differences in spinal curvature between specific sub-sets of LBP population could provide useful information on sitting postures.

Aims: Surgery for degenerative lumbar spondylolisthesis may entail both decompression and fusion. The knee-chest position facilitates decompression, but fixation in this position risks fusion in kyphosis. This can be avoided by intra-operative re-positioning to the prone position. The aim of our study was to quantify restoration of lordosis achieved by intra-operative repositioning and to assess clinical and radiological outcome.

Patients and method: Thirty-six patients with degenerative lumbar spondylolisthesis and stenosis were treated by posterior decompression and interbody fusion with pedicle screw fixation. The decompression, interbody grafting and screw insertion were performed with the patient in the knee-chest position. The patient was repositioned to the prone position for fusion. Sagittal plane angles were measured pre, intra and post-operatively. Clinical assessment was performed using SF-36 scores and visual analogue scores for back and leg pain.

Results: The median pre-operative sagittal angle between fused spinal segments was 16.0 degrees lordosis. Intra-operatively in the knee-chest position the sagittal angle was median 13.5 degrees and after changing to the prone position increased to median 27.1 degrees. On the initial post-operative lumbar radiographs the sagittal angle was 23.1 and this was maintained at 6 months post-operatively (22.5 degrees). Overall there was a mean increase in lordosis angle after repositioning of 7.1 degrees per operative level (p< 0.01). The SF-36 scores improved for 7 out of 8 domains and the physical score improved from 29% to 40% (p< 0.05). Mean pain scores improved from 7.5 to 3.8 for back pain and from 7.6 to 3.7 for leg pain (p< 0.001).

Conclusion: Lumbar spondylolisthesis was found to be associated with a reduction of normal lumbar lordosis. The knee-chest position exacerbates this loss of lordosis. Intra-operative repositioning restores lordosis to greater than the pre-operative angle and was associated with a good clinical outcome.

Introduction: Loss of the cervical lordosis is a common finding on the emergency department in patients who have been involved in a car accident as well as in those who have suffered head and neck injury. The difficult circumstances, under which the plain films are usually taken, make the use of CT indispensable. Our study presents the CT findings from the cervical spine in patients with loss of the cervical lordosis.

Method-Patients We studied 120 patients from February 2003 to January 2004. Their mean age was 37 years old. Our protocol included the lateral-AP view, while in the absence of findings, except loss of cervical lordosis, from the plain films, the patients underwent spiral CT within 24 h.

Results: Fractures of the cervical spine were found in 7 patients (5,8%). In 5 of them these involved the A1–A2 level. In two patients fractures of the occipital condyles were found. One A7 fracture coexisted with an A2 fracture. No patient had neurological symptoms.

Conclusions: The complete investigation of the cervical spine at the emergency department is often quite difficult. The possible underlying injuries can be potentially life threatening. The percentage of positive findings in our study is quite high to justify the routine use of spiral CT for the detailed investigation of such patients.

An often neglected component of sagittal balance in adolescent idiopathic scoliosis (AIS) is the cervical spine. The cervical spine is capable of compensating for large sagittal deformities by altering head position, but in doing so may give rise to symptoms when the extremes of cervical compensatory mechanisms are reached. This paper seeks to define whether AIS patients have a different cervical lordosis pre and post corrective surgery when compared to normal adolescents.

A review of the literature was carried out in order to define normal cervical lordosis in adolescents. A retrospective analysis of 81 patients with a confirmed diagnosis of idiopathic scoliosis who had received corrective surgery was carried out, and pre and post op cervical lordosis of C1– C7 and C2– C7 were independently measured and recorded using full length sagittal spine radiographs. This data was compared to the 95% confidence interval (95% CI) of cervical lordosis in controls to show if AIS patients showed different cervical spine lordosis before or after corrective surgery.

A literature search showed that normal cervical spine lordosis values are poorly described. However, some values have been published. One study (paper A) gives values of −16° (95%CI −12–20°) for male C2– C7 lordosis and −15° (95% CI −12.5–17.5°) for female C2– C7 adolescents. Another reference (paper B) gives values of −8.4 (95%CI −6.7–10.1°) for male and −1.9 (95%CI −0.5–3.3°) for female adolescents for the same C2– C7 measurements. Our values for male patients for pre op C2– C7 lordosis was −1.2 (95%CI −8.5–6.1°) and 9° (95%CI 2.9– 15.1°) for females. Post op values were 10.6° (95%CI 2.4–18.8°) for males and 8.3° (95%CI 4.8–11.8°) for females.

The values of cervical lordosis in our series show that patients with AIS have a significantly different cervical lordosis when compared to normal values both pre and post deformity correction (p < 0.05). A complete understanding of how the cervical spine is positioned prior to surgery is critical, as flattening the thoracic spine during corrective surgery could give rise to cervical pain and sagittal imbalance if the ability of the cervical spine to compensate for the new spinal position is exceeded.

Introduction: posterior lumbar interbody fusion can theoretically allow neural decompression directly and by restoration of disc height and appropriate lumbar lordosis. The technique of insertion of a trapezoidal lordotic wedge spacer (ramp) into the disc space before rotating it into position theoretically will obtain both an increase in disc height and allow correction of lordosis. However observations suggest that incongruity between a flat implant and a curved end plate, and possible settling of the implant into the vertebral body may limit the ability of the technique to achieve its full theoretical potential. This paper attempts to establish the capacity of this technique to (1) restore disc height, and (2) alter segmental lordosis.

Methods: pre- and post-operative lateral radiographs were obtained from 34 patients who had undergone posterior lumbar interbody fusion using carbon fibre spacers with a lordotic angle of five degrees. Supplemental pedicle screws were used in all cases. The procedure was performed at l2/3 in one case, at l3/4 in two cases, at l4/5 16 cases and l5/1 in 15 cases. Measurements of pre- and post-operative lordosis, anterior and posterior disc height, slip percentage and anterior and posterior positioning of the prosthesis were made. To allow for comparison of length measurements the raw data were normalised by dividing by the inferior end plate length.

Results: stepwise multiple linear regression showed the only variable to be related to final post-operative lordosis was pre-operative lordosis (p = 0.026). There was no relationship between final lordosis and implant placement or slip percentage. The regression line suggested that small pre-operative segmental angles (less than 7.5 degrees) were increased post-operatively while large pre-operative angles (greater than 7.5 degrees) were reduced. This suggests that the segment is attempting to accommodate to the five-degree implant. The regression equation only explains 14% of the total variance (r² = 0.144). The mean normalised posterior disc height increased significantly by 55% (0.1195 to 0.1844) (paired t test p < 0.0001) and the mean normalised anterior disc height increased by 18% (0.27151 to 0.32251) (paired t test p < 0.007). Changes in both anterior and posterior disc height were highly correlated with pre-operative disc height (r = −0.6729 p < 0.0001, r = −0.7402 p < 0.0001).

Discussion: posterior lumbar interbody fusion using a five degree wedged spacer can lead to significant improvements in anterior and posterior disc height when the disc space is narrowed and maintain disc height when the disc height is normal. The insertion of a wedged implant causes the segment to approximate the lordosis of the implant. The variation is however large. Possible causes for this variation are a mismatch between the flat implant and a curved end plate and end plate subsidence. Having a curved implant end plate and a selection of lordotic angles may possibly reduce the former effect.

Introduction: In total hip arthroplasty, the angle of acetabular component is a critical factor for the postoperative dislocation and the longevity of prostheses. The angle is principally determined in relation to anterior pelvic plane. It is reported that the pelvis tends to tilt posteriorly along with aging. Furthermore, the pelvic tilt might change after THA. The changes might be infiuenced by the hip condition and lumbar lordosis. We measured the pelvic tilt and the lumbar lordosis, and evaluated the effects of contralateral hip and lumbar lordosis on pelvic tilt after THA.

Materials and Methods: Fifty-one unilateral patients and 30 bilateral patients were enrolled in this study. The diagnosis was dysplastic osteoarthritis in all patients. In unilateral patients, the hip was affected in one side and the other hip was normal or acetabular dysplasia without symptoms. In bilateral patients, THAs in both hips were done within two months.

Pelvic inclination angle (PIA) and lumbar lordotic angle (LLA) were measured on the standing lateral X-rays before operation and 1-month, 6-month and 1-year post-operation. The effects of patient age, BMI, ROM of the hip, preoperative PIA and LLA on the changes of PIA were statistically investigated using multiple linear regression analysis. We divided the patients into three groups with regard to pre-operative PIA (anterior group: PIA < 0, intermediate group: 0 < PIA < 10, posterior group: PIA > 10) and with regard to pre-operative LLA (insufficient group: LLA < 20, moderate group: 20 < LLA < 40, severe group: LLA > 40).

Results: Overall, significant factor was only preoperative PIA. In bilateral cases, preoperative PIA and patient age affected the changes of PIA after THA. In patients with severe lordosis, preoperative PIA and LLA were significant factors. PIA increased in anterior tilt group and PIA did not change in intermediate group, while PIA gradually decreased in posterior group. In insufficient lordosis group, PIA remarkably increased after THA compared with that in severe group.

Discussion: Pelvic tilt after THA has been reported without considering the conditions of contralateral hip and lumbar spine. By categorizing patients with regard to the conditions of hips and lumbar spine, we can prospect the tendency of the direction of PIA changes. These results indicated that pre-operative PIA was related the changes of PIA in bilateral group. PIA slightly increased in all bilateral patients, PIA tended to close each other in unilateral patients. Further investigation is necessary to prospect the estimated PIA value after THA.

Introduction and Aims: Surgery for degenerative lumbar spondylolisthesis may entail both decompression and fusion. The knee-chest position facilitates decompression, but fixation in this position risks fusion in kyphosis. This can be avoided by intra-operative re-positioning to the fully prone position. We aim to quantify restoration of lordosis achieved by this manoeuvre.

Method: Thirty-six patients with degenerative lumbar spondylolisthesis and stenosis were treated by posterior decompression and interbody fusion with pedicle screw fixation (without interbody cages). There were 16 men and 20 women with a mean age of 58.2 years (32–80). The decompression, interbody grafting and screw insertion were performed with the patient in the knee-chest position. The patient was repositioned to the fully prone position for subsequent fusion. The sagittal plane angle was measured on the pre-operative, intra-operative and post-operative x-rays. Short-Form 36 (SF-36) scores and Visual Analogue Scales (VAS) for pain (0 to 10) were determined pre- and post-operatively.

Results: Twenty-eight patients underwent single-level fusion, two patients had two levels, two patients had three levels and four patients had four levels fused. The mean pre-operative sagittal angle between the operated vertebrae was 15.7 degrees lordosis, and the intra-operative angle before re-positioning was 14.9 degrees. The mean immediate post-operative angle was 23.7, and at six-month follow-up the angle was 23.1. Overall there was a mean increase in lordosis angle after repositioning of 8.0 degrees per operative level (p< 0.01). The mean scores of the SF-36 improved in all eight domains and this was significant (p< 0.05) for social functioning (44.4 to 68.9), energy and vitality (36.0 to 49.5), pain (23.8 to 58.3) and general health perception (51.4 to 65.6). Mean VAS pain scores for back pain improved from 7.47 pre-operatively to 3.84 post-operatively (p< 0.001); and for leg pain improved from 7.56 to 3.78 (p< 0.001). No complications attributable to the manoeuvre occurred.

Conclusion: Lumbar spondylolisthesis was found to be associated with reduction of normal lumbar lordosis. The knee-chest position for surgery exacerbates this loss of lordosis. Intra-operative repositioning restores lordosis to greater than the pre-operative angle, which may improve clinical outcome.

Aims

To report the outcome of spinal deformity correction through anterior spinal fusion in wheelchair-bound patients with myelomeningocele.

Aim:

To simplify sagittal plane spinal assessment by describing a single novel angle in the lumbar spine equivalent to the difference between pelvic incidence (PI) and lumbar lordosis (LL) and evaluate its reliability.

We determined the frequency, rate and extent of development of scoliosis (coronal plane deformity) in wheelchair-dependent patients with Duchenne muscular dystrophy (DMD) who were not receiving steroid treatment. We also assessed kyphosis and lordosis (sagittal plane deformity). The extent of scoliosis was assessed on sitting anteroposterior (AP) spinal radiographs in 88 consecutive non-ambulatory patients with DMD. Radiographs were studied from the time the patients became wheelchair-dependent until the time of spinal fusion, or the latest assessment if surgery was not undertaken. Progression was estimated using a longitudinal mixed-model regression analysis to handle repeated measurements.

Scoliosis ≥ 10° occurred in 85 of 88 patients (97%), ≥ 20° in 78 of 88 (89%) and ≥ 30° in 66 of 88 patients (75%). The fitted longitudinal model revealed that time in a wheelchair was a highly significant predictor of the magnitude of the curve, independent of the age of the patient (p <  0.001). Scoliosis developed in virtually all DMD patients not receiving steroids once they became wheelchair-dependent, and the degree of deformity deteriorated over time.

In general, scoliosis increased at a constant rate, beginning at the time of wheelchair-dependency (p < 0.001). In some there was no scoliosis for as long as three years after dependency, but scoliosis then developed and increased at a constant rate. Some patients showed a rapid increase in the rate of progression of the curve after a few years – the clinical phenomenon of a rapidly collapsing curve over a few months.

A sagittal plane kyphotic deformity was seen in 37 of 60 patients (62%) with appropriate radiographs, with 23 (38%) showing lumbar lordosis (16 (27%) abnormal and seven (11%) normal).

This study provides a baseline to assess the effects of steroids and other forms of treatment on the natural history of scoliosis in patients with DMD, and an approach to assessing spinal deformity in the coronal and sagittal planes in wheelchair-dependent patients with other neuromuscular disorders.

Cite this article: Bone Joint J 2014;96-B:100–5.

Purpose: To review the sagittal lumbar and clinical profile of the two surgical procedures: TLIF (transforaminal lumbar interbody fusion and ALIF (anterior lumbar interbody fusion).

Materials and methods: We carried out a retrospective study of 46 patients who underwent circumferential fusion in 2000–2001. TLIF was used in the first group (21) and ALIF in the second (25). The posterior approach with pedicle instrumentation was used in all patients. Lateral radiographs of the lumbar spine in neutral position and bipedestation were used for evaluation before and after surgery and during follow-up. The results were compared statistically using the Wilcoxon matched pairs test.

Results: Lumbar lordosis was achieved with both techniques: TLIF+PF(posterior fusion) −33° (preoperative), −46° (postoperative) and ALIF+ PF −49° (preoperative), −54° (postoperative). However the height of the disc improved significantly with the anterior approach: TLIF+ PF 0.62 (preoperative), 1.35 (postoperative) and ALIF+PF 1 (preoperative), 4.65 (postoperative).

The duration of surgery, blood loss and hospital stay were greater with ALIF+PF than with TLIF+PF.

Conclusions: TLIF+PF has clinical and economic advantages over ALIF+PF. Lumbar lordosis and the area of instrumented lordosis was achieved with both circumferential fusion procedures and the only radiographic difference was the restoration of the disc height with ALIF.

We investigated the relationship between spinopelvic parameters and disc degeneration in young adult patients with spondylolytic spondylolisthesis. A total of 229 men with a mean age of 21 years (18 to 26) with spondylolytic spondylolisthesis were identified. All radiological measurements, including pelvic incidence, sacral slope, pelvic tilt, lumbar lordosis, sacral inclination, lumbosacral angle (LSA), and sacrofemoral distance, were calculated from standing lateral lumbosacral radiographs. The degree of intervertebral disc degeneration was classified using a modified Pfirrmann scale. We analysed the spinopelvic parameters according to disc level, degree of slip and disc degeneration.

There were significant positive correlations between the degree of slip and pelvic incidence (p = 0.009), sacral slope (p = 0.003) and lumbar lordosis (p = 0.010). The degree of slip and the LSA were correlated with disc degeneration (p < 0.001 and p = 0.003, respectively). There was also a significant difference between the degree of slip (p < 0.001) and LSA (p = 0.006) according to the segmental level of disc degeneration.

Cite this article: Bone Joint J 2013;95-B:1239–43.

Adult Spine Deformity (ASD) is a degenerative condition of the adult spine leading to altered spine curvatures and mechanical balance. Computational approaches, like Finite Element (FE) Models have been proposed to explore the etiology or the treatment of ASD, through biomechanical simulations. However, while the personalization of the models is a cornerstone, personalized FE models are cumbersome to generate. To cover this need, we share a virtual cohort of 16807 thoracolumbar spine FE models with different spine morphologies, presented in an online user-interface platform (SpineView). To generate these models, EOS images are used, and 3D surface spine models are reconstructed. Then, a Statistical Shape Model (SSM), is built, to further adapt a FE structured mesh template for both the bone and the soft tissues of the spine, through mesh morphing. Eventually, the SSM deformation fields allow the personalization of the mean structured FE model, leading to generate FE meshes of thoracolumbar spines with different morphologies. Models can be selectively viewed and downloaded through SpineView, according to personalized user requests of specific morphologies characterized by the geometrical parameters: Pelvic Incidence; Pelvic Tilt; Sacral Slope; Lumbar Lordosis; Global Tilt; Cobb Angle; and GAP score. Data quality is assessed using visual aids, correlation analyses, heatmaps, network graphs, Anova and t-tests, and kernel density plots to compare spinopelvic parameter distributions and identify similarities and differences. Mesh quality and ranges of motion have been assessed to evaluate the quality of the FE models. This functional repository is unique to generate virtual patient cohorts in ASD. Acknowledgements: European Commission (MSCA-TN-ETN-2020-Disc4All-955735, ERC-2021-CoG-O-Health-101044828)

The spinopelvic alignment is often assessed via the Pelvic Incidence-Lumbar Lordosis (PI-LL) mismatch. Here we describe and validate a simplified method to evaluating the spinopelvic alignment through the L1-Pelvis angle (L1P). This method is set to reduce the operator error and make the on-film measurement more practicable. 126 standing lateral radiographs of patients presenting for Total Hip Arthroplasty were examined. Three operators were recruited to label 6 landmarks. One operator repeated the landmark selection for intra-operator analysis. We compare PI-LL mismatch obtained via the conventional method, and our simplified method where we estimate this mismatch using PI-LL = L1P - 90°. We also assess the method's reliability and repeatability. We found no significant difference (p > 0.05) between the PI-LL mismatch from the conventional method (mean 0.22° ± 13.6) compared to L1P method (mean 0.0° ± 13.1). The overall average normalised root mean square error (NRMSE) for PI-LL mismatch across all operators is 7.53% (mean -3.3° ± 6.0) and 6.5% (mean -2.9° ± 4.9) for the conventional and L1P method, respectively. In relation to intra-operator repeatability, the correlation coefficients are 0.87 for PI, 0.94 for LL, and 0.96 for L1P. NRMSE between the two measurement sets are PI: 9.96%, LL: 5.97%, and L1P: 4.41%. A similar trend is observed in the absolute error between the two sets of measurements. Results indicate an equivalence in PI-LL measurement between the methods. Reproducibility of the measurements and reliability between operators were improved. Using the L1P angle, the classification of the sagittal spinal deformity found in the literature translates to: normal L1P<100°, mild 100°<L1P<110°, and severe L1P>110°. Surgeons adopting our method should expect a small improvement in reliability and repeatability of their measurements, and a significant improvement of the assessment of the mismatch through the visualisation of the angle L1P

Study Design: The effect of Total Hip Replacement surgery (THR) upon spinal sagittal alignment and low back pain was assessed in patients with severe hip osteoarthritis. Summary of Background Data: Osteoarthritis in the hip joint is associated with abnormal posture and gait due to hip flexion contracture and hip pain. This in turn may cause abnormal spinal sagittal alignment and secondarily induce low back and leg pain. However, there have been no reports regarding the corrective effect of Total Hip Replacement surgery upon spinal sagittal alignment in patients with osteoarthritis of the hip. Methods: This study prospectively analyzed the results of 25 patients (15 females and 10 males, average age 67.4 years (32–84)) undergoing THR for severe osteoarthritis of the hip. Pre and post-surgical assessment included; sagittal measurement of Sacral Inclination (SI) and total Lumbar Lordosis (L1-S1) on standing lateral radiographs. Functional clinical outcomes for hip as well as low back were also evaluated using the Oswestry back Questionnaire, the Modified Harris Hip Score and Visual Analog Scale for lower back pain and hip pain accordingly. All the radiographic and clinical evaluations were completed both before THR surgery and 3 months following the surgery during routine follow up. Results: Mean Lumbar Lordosis before the surgery and in the follow up was 50.36 and 50.32 respectively. Mean sacral inclination before and after surgery were 39.06 and 38.16 respectively. Mean Functional outcomes as assessed by the HHS score before and after the surgery were 45.74 and 81.8 respectively. Mean Oswestry Questionnaire scores before and after the surgery were 36.72 and 24.08 respectively. Mean VAS scores for hip pain before and after the surgery were 7.08 and 2.52 respectively. Mean VAS scores for lower back pain before and after the surgery were 5.04 and 3.68 respectively. Discussion: No Significant difference was found between the sagittal alignment of the spine before THR and 3 months following it. Interestingly, total hip replacement surgery significantly improved spinal functional outcome as well as relieved low back and hip pain