Introduction. Upright body posture is maintained with the alignment of the spine, pelvis, and lower extremities, and the muscle strength of the body trunk and lower extremities. Conversely, the posture is known to undergo changes with age, and muscle weakness of lower extremities and the restriction of knee extension in osteoarthritis of the knee (knee OA) have been considered to be associated with loss of natural lumbar lordosis and abnormal posture. As total knee arthroplasty (TKA) is aimed to correct malalignment of lower extremities and limited range of motion of knee, particularly in extension, we hypothesized that TKA positively affects the preoperative abnormal posture. To clarify this, the variation in the alignment of the spine, pelvis, and lower extremities before and after TKA was evaluated in this study. Patients and methods. Patients suffering from primary knee OA who were scheduled to receive primary TKA were enrolled in this study. However, patients with arthritis secondary to another etiology, i.e. rheumatoid arthritis, trauma, or previous surgical interventions to the knee, were excluded. Moreover, patients who suffered from hip and ankle OA, cranial nerve diseases, or severe spinal deformity were also excluded. The sagittal vertical axis (SVA), the horizontal distance between the posterosuperior aspect of the S1 endplate surface and a vertical plumb line drawn from the center of the C7 vertebral body, is an important index of sagittal balance of the trunk. Thus, patients were classified into two groups based on the preoperative SVA with preoperative standing lateral digital radiographs: normal (< 40mm) and abnormal (≥ 40mm) groups. The variations in the sagittal alignment of the spine, pelvis and lower extremities were evaluated preoperatively, and at 1 and 3 months postoperatively. This study was approved by an institutional review board, and informed consent for participation was obtained from the patients. Results. Forty-nine knees in 49 patients were enrolled. Three different patterns of postural changes as well as hip and knee angles following TKA were observed. After TKA, the preoperatively normal SVA patients (26.5%) showed extension of the hip and knee joints and decrease of lumbar lordosis, while the SVA remained almost within the normal range. In the preoperatively abnormal SVA group, 13 patients (26.5%) showed extension of the knee joint while the SVA remained abnormal, however, 23 of the preoperatively abnormal SVA group patients (47.0%) showed improvement of SVA into the normal range with the extension of the hip and knee joints. Discussion. As the spine, pelvis, and lower extremities together affect body alignment, once limitation of knee extension due to severe knee OA is corrected and lower extremity alignment is improved with TKA, the lumbar lordosis may increase, and SVA could decrease. Recently, the relationship between the imbalance of the sagittal plane of the body and the risk of falls was described. From this, it could be said that TKA not only helped in recovering knee function and lower extremity alignment in severe knee OA, but also helped to improve posture and to protect from falls

Introduction. Pelvic flexion and extension in different body positions can affect acetabular orientation after total hip arthroplasty, and this may predispose patients to dislocation. The purpose of this study was to evaluate functional acetabular component position in total hip replacement patients during standing and sitting. We hypothesize that patients with degenerative lumbar disease will have less pelvic extension from standing to sitting, compared to patients with a normal lumbar spine or single level spine disease. Methods. A prospective cohort of 20 patients with primary unilateral THR underwent spine-to-ankle standing and sitting lateral radiographs that included the lumbar spine and pelvis using EOS imaging. Patients were an average age of 58 ± 12 years and 6 patients were female. Patients had (1) normal lumbar spines or single level degeneration, (2) multilevel degenerative disc disease or (3) scoliosis. We measured acetabular anteversion (cup relative to the horizontal), sacral slope angle (superior endplate of S1 relative to the horizontal), and lumbar lordosis angles (superior endplates of L1 and S1). We calculated the absolute difference in acetabular anteversion and the absolute difference in lumbar lordosis during standing and sitting (Figure 1). Results. Nine patients had normal lumbar spines or scoliosis, and 11 patients had multilevel disc disease. The median change in cup anteversion for normal and scoliosis patients was 29° degrees (range 11° to 41°) compared to 21° degrees (range 1° to 34°) for multilevel disc disease patients (p=0.03). There was a positive correlation between the change in cup anteversion and the change in lumbar lordosis (p=0.01; Figure 2). From standing to sitting, cup anteversion always increased and lumbar lordosis always decreased. Conclusions. The change in cup anteversion from standing to sitting was variable in patients with normal, degenerative, and scoliosis lumbar spines. Patients with degenerative disc disease have less pelvic extension, and thus less acetabular anteversion in the sitting position compared to normal spines. This may increase their risk of posterior dislocation

Spinopelvic mobility describes the change in lumbar lordosis and pelvic tilt from standing to sitting position. For 1° of posterior pelvic tilt, functional cup anteversion increases by 0.75° after total hip arthroplasty (THA). Thus, spinopelvic mobility is of high clinical relevance regarding the risk of implant impingement and dislocation. Our study aimed to 1) determine the proportion of OA-patients with stiff, normal or hypermobile spino-pelvic mobility and 2) to identify clinical or static standing radiographic parameters predicting spinopelvic mobility. This prospective diagnostic cohort study followed 122 consecutive patients with end-stage osteoarthritis awaiting THA. Preoperatively, the Oxford Hip Score, Oswestry Disability Index and Schober's test were assessed in a standardized clinical examination. Lateral view radiographs were taken of the lumbar spine, pelvis and proximal femur using EOS© in standing position and with femurs parallel to the floor in order to achieve a 90°-seated position. Radiographic measurements were performed for the lumbar lordosis angle (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI) and pelvic-femoral-angle (PFA). The difference in PT between standing and seated allowed for patient classification based on spino-pelvic mobility into stiff (±30°). From the standing to the sitting position, the pelvis tilted backwards by a mean of 19.6° (SD 11.6) and the hip was flexed by a mean of 57° (SD 17). Change in pelvic tilt correlated inversely with change in hip flexion. Spinopelvic mobility is highly variable in patients awaiting THA and we could not identify any clinical or static standing radiographic parameter predicting the change in pelvic tilt from standing to sitting position. In order to identify patients with stiff or hypermobile spinopelvic mobility, we recommend performing lateral view radiographs of the lumbar spine, pelvis and proximal femur in all patients awaiting THA. Thereafter, implants and combined cup inclination/anteversion can be individually chosen to minimize the risk of dislocation. No predictors could be identified. We recommend performing sitting and standing lateral view radiographs of the lumbar spine and pelvis to determine spinopelvic mobility in patients awaiting THA

A stiff spine leads to increased demand on the hip, creating an increased risk of total hip arthroplasty (THA) dislocation. Several authors propose that a change in sacral slope of ≤10° between the standing and relaxed-seated positions (ΔSSstanding→relaxed-seated) identifies a patient with a stiff lumbar spine and have suggested use of dual-mobility bearings for such patients. However, such assessment may not adequately test the lumbar spine to draw such conclusions. The aim of this study was to assess how accurately ΔSSstanding→relaxed-seated can identify patients with a stiff spine. This is a prospective, multi-centre, consecutive cohort series. Two-hundred and twenty-four patients, pre-THA, had standing, relaxed-seated and flexed-seated lateral radiographs. Sacral slope and lumbar lordosis were measured on each functional X-ray. ΔSSstanding→relaxed-seated seated was determined by the change in sacral slope between the standing and relaxed-seated positions. Lumbar flexion (LF) was defined as the difference in lumbar lordotic angle between standing and flexed-seated. LF≤20° was considered a stiff spine. The predictive value of ΔSSstanding→relaxed-seated for characterising a stiff spine was assessed. A weak correlation between ΔSSstanding→relaxed-seated and LF was identified (r2= 0.15). Fifty-four patients (24%) had ΔSSstanding→relaxed-seated ≤10° and 16 patients (7%) had a stiff spine. Of the 54 patients with ΔSSstanding→relaxed-seated ≤10°, 9 had a stiff spine. The positive predictive value of ΔSSstanding→relaxed-seated ≤10° for identifying a stiff spine was 17%. ΔSSstanding→relaxed-seated ≤10° was not correlated with a stiff spine in this cohort. Utilising this simplified approach could lead to a six-fold overprediction of patients with a stiff lumbar spine. This, in turn, could lead to an overprediction of patients with abnormal spinopelvic mobility, unnecessary use of dual mobility bearings and incorrect targets for component alignment. Referring to patients ΔSSstanding→relaxed-seated ≤10° as being stiff can be misleading; we thus recommend use of the flexed-seated position to effectively assess pre-operative spinopelvic mobility

The presence of hip osteoarthritis is associated with abnormal spinopelvic characteristics. This study aims to determine whether the pre-operative, pathological spinopelvic characteristics “normalize” at 1-year post-THA. This is a prospective, longitudinal, case-control matched cohort study. Forty-seven patients underwent pre- and post- (at one-year) THA assessments. This group was matched (age, sex, BMI) with 47 controls/volunteers with well-functioning hips. All participants underwent clinical and radiographic assessments including lateral radiographs in standing, upright-seated and deep-flexed-seated positions. Spinopelvic characteristics included change in lumbar lordosis (ΔLL), pelvic tilt (ΔPT) and hip flexion (pelvic-femoral angle, ΔPFA) when moving from the standing to each of the seated positions. Spinopelvic hypermobility was defined as ΔPT>30° between standing and upright-seated positions. Pre-THA, patients illustrated less hip flexion (ΔPFA −54.8°±17.1° vs. −68.5°± 9.5°, p<0.001), greater pelvic tilt (ΔPT 22.0°±13.5° vs. 12.7°±8.1°, p<0.001) and greater lumbar movements (ΔLL −22.7°±15.5° vs. −15.4°±10.9°, p=0.015) transitioning from standing to upright-seated. Post-THA, these differences were no longer present (ΔPFApost −65.8°±12.5°, p=0.256; ΔPTpost 14.3°±9.5°, p=0.429; ΔLLpost −15.3°±10.6°, p=0.966). The higher prevalence of pre-operative spinopelvic hypermobility in patients compared to controls (21.3% vs. 0.0%; p=0.009), was not longer present post-THA (6.4% vs. 0.0%; p=0.194). Similar results were found moving from standing to deep-seated position post-THA. Pre-operative, spinopelvic characteristics that contribute to abnormal mechanics can normalize post-THA following improvement in hip flexion. This leads to patients having the expected hip-, pelvic- and spinal flexion as per demographically-matched controls, thus potentially eliminating abnormal mechanics that contribute to the development/exacerbation of hip-spine syndrome

Introduction. We propose that Total Hip Replacement with correction of fixed flexion deformity of the hip and exaggerated lumbar lordosis will result in relief of symptoms from spinal stenosis, possibly avoiding a spinal surgery. A sequence of patients with this dual pathology has been assessed to examine this and suggest a possible management algorithm. Materials and methods. A retrospective study of 19 patients who presented with dual pathology was performed and the patients were assessed with regards to pre and post-operative symptoms, walking distance, and neurological status. Results. There were 17 patients with improvement in the spinal stenotic symptoms following hip replacement to an extent that none required spinal surgery. There were two patients who had spinal surgery after THR, at varying lengths following hip replacements as their spinal stenotic symptoms worsened over time, and had lateral spinal stenosis on MRI. Discussion. In advanced hip osteoarthritis, a fixed flexion deformity may develop at the hip leading to an exaggerated lumbar lordosis in erect posture. In the presence of co-existing spinal stenosis, the exaggerated lumbar lordosis may worsen the spinal stenotic symptoms while standing and walking. Cadaveric & Radiological studies have shown that canal narrowing occurs with increased lordosis/ extension in the lumbar spine. Our findings suggest that when central lumbar spinal stenosis coexists with bilateral hip arthritis and FFD at the hip, THR should be offered first. Successful hip surgery for arthritis correcting significant fixed flexion deformity would lessen the lumbar lordosis, thus correcting the excessive pathological narrowing. If a patient is fit enough, simultaneous bilateral THR via an anterior type of approach makes surgical correction of FFD easier. Although it has been suggested in the literature that patients with spinal stenosis have a increased risk of neurological impairment following THR, we did not find any clear association

The study of spinopelvic anatomy and movement has received great interest as these characteristics influence the biomechanical behavior (and outcome) following hip arthroplasty. However, to-date there is little knowledge of what “normal” is and how this varies with age. This study aims to determine how dynamic spino-pelvic characteristics change with age, with well-functioning hips and assess how these changes are influenced by the presence of hip arthritis. This is an IRB-approved, cross-sectional, cohort study; 100 volunteers (asymptomatic hips, Oxford-Hip-sore>45) [age:53 ± 17 (24-87) years-old; 51% female; BMI: 28 ± 5] and 200 patients with end-stage hip arthritis [age:56 ± 19 (16-89) years-old; 55% female; BMI:28 ± 5] were studied. All participants underwent lateral spino-pelvic radiographs in the standing and deep-seated positions to determine maximum hip and spine flexion. Parameters measured included lumbar-lordosis (LL), pelvic incidence, pelvic-tilt (PT), pelvic-femoral angles (PFA). Lumbar flexion (ΔLL), hip flexion (ΔPFA) and pelvic movement (ΔPT) were calculated. The prevalence of spinopelvic imbalance (PI–LL>10?) was determined. There were no differences in any of the spino-pelvic characteristics or movements between sexes. With advancing age, standing LL reduced and standing PT increased (no differences between groups). With advancing age, both hip (4%/decade) and lumbar (8%/decade) flexion reduced (p<0.001) (no difference between groups). ΔLL did not correlate with ΔPFA (rho=0.1). Hip arthritis was associated with a significantly reduced hip flexion (82 ±;22? vs. 90 ± 17?; p=0.003) and pelvic movements (1 ± 16? vs. 8 ± 16?; p=0.002) at all ages and increased prevalence of spinopelvic imbalance (OR:2.6; 95%CI: 1.2-5.7). With aging, the lumbar spine loses its lumbar lordosis and flexion to a greater extent that then the hip and resultantly, the hip's relative contribution to the overall sagittal movement increases. With hip arthritis, the reduced hip flexion and the necessary compensatory increased pelvic movement is a likely contributor to the development of hip-spine syndrome and of spino-pelvic imbalance

Adverse spinopelvic characteristics (ASC) have been associated with increased dislocation risk following primary total hip arthroplasty (THA). A stiff lumbar spine, a large posterior standing tilt when standing and severe sagittal spinal deformity have been identified as key risk factors for instability. It has been reported that the rate of dislocation in patients with such ASC may be increased and some authors have recommended the use of dual mobility bearings or robotics to reduce instability to within acceptable rates (<2%). The aims of the prospective study were to 1: Describe the true incidence of ASC in patients presenting for a THA 2. Assess whether such characteristics are associated with greater symptoms pre-THA due to the concomitant dual pathology of hip and spine and 3. Describe the early term dislocation rate with the use of ≤36mm bearings. This is an IRB-approved, two-center, multi-surgeon, prospective, consecutive, cohort study of 220 patients undergoing THA through anterolateral- (n=103; 46.8%), direct anterior- (n=104; 27.3%) or posterior- approaches (n=13; 5.9%). The mean age was 63.8±12.0 years (range: 27.7-89.0 years) and the mean BMI 28.0±5.0 kg/m. 2. (range: 19.4-44.4 kg/m. 2. ). There were 44 males (47.8%) and 48 females (52.2%). The mean follow-up was 1.6±0.5 years. Overall, 54% of femoral heads was 32 mm, and 46% was 36mm. All participants underwent lateral spinopelvic radiographs in the standing and deep-flexed seated positions were taken to determine lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic-femoral angle (PFA) and pelvic incidence (PI) in both positions. Spinal stiffness was defined as lumbar flexion <20° when transitioning between the standing and deep-seated position; adverse standing PT was defined as >19° and adverse sagittal lumbar balance was defined as mismatch between standing PI and LL >10°. Pre-operative patient reported outcomes was measured using the Oxford Hip Score (OHS) and EuroQol Five-Dimension questionnaire (EQ-5D). Dislocation rates were prospectively recorded. Non-parametric tests were used, significance was set at p<0.05. The prevalence of PI-LL mismatch was 22.1% (43/195) and 30.4% had increased standing PT (59/194). The prevalence of lumbar stiffness was 3.5% (5/142) and these patients had all three adverse spinopelvic characteristics (5/142; 3.5%). There was no significant difference in the pre-operative OHS between patients with (20.7±7.6) and patients without adverse spinopelvic characteristics (21.6±8.7; p=0.721), nor was there for pre-operative EQ5D (0.651±0.081 vs. 0.563±0.190; p=0.295). Two patients sustained a dislocation (0.9%): One in the lateral (no ASC) and one in the posterior approaches, who also exhibited ASC pre-operatively. Sagittal lumbar imbalance, increased standing spinal tilt and spinal stiffness are not uncommon among patients undergoing THA. The presence of such characteristics is not associated with inferior pre-operative PROMs. However, when all characteristics are present, the risk of instability is increased. Patients with ASC treated with posterior approach THA may benefit from the use of advanced technology due to a high risk of dislocation. The use of such technology with the anterior or lateral approach to improve instability is to date unjustified as the rate of instability is low even amongst patients with ASCs

Introduction. Excessive standing posterior pelvic tilt (PT), lumbar spine stiffness, low pelvic Incidence (PI), and severe sagittal spinal deformity (SSD) have been linked to increased dislocation rates. We aimed to compare the prevalence of these 4 parameters in unstable and stable primary Total Hip Arthroplasty (THA) patients. Methods. In this retrospective cohort study, 40 patients with instability following primary THA for osteoarthritis were referred for functional analysis. All patients received lateral X-rays in standing and flexed seated positions to assess functional pelvic tilt and lumbar lordosis (LL). Computed tomography scans were used to measure pelvic incidence and acetabular cup orientation. Literature thresholds for “at risk” spinopelvic parameters were standing pelvic tilt ≤ −10°, lumbar flexion (LL. stand. – LL. seated. ) ≤ 20°, PI ≤ 41°, and sagittal spinal deformity (PI – LL. stand. mismatch) ≥ 10°. The prevalence of each risk factor in the dislocation cohort was calculated and compared to a previously published cohort of 4042 stable THA patients. Results. Median supine cup inclination for the dislocating cohort was 43° (range, 26°- 58°). Median cup anteversion was 23° (range, 7° − 40°) for the dislocating cohort. 65% of the dislocating patients had socket positions within the Lewinnek safe zone (Figure 1). Standing PT (-10° v −1°), lumbar flexion (20° v 45°), and PI-LL mismatch (12° v −1°) were all significantly different (p < 0.001) in the dislocating group compared to the stable THA population (Figure 2). There was no difference in PI between the dislocating group and the stable THA population (58° v 56° respectively, p = 0.33), with the numbers available. 80% of the dislocating patients had one or more of the 3 statistically significant risk factors, compared to only 24% of the stable THA population. Conclusion. Excessive standing posterior pelvic tilt, low lumbar flexion and a severe SSD are highly prevalent in unstable THAs. Pre-op screening for these parameters may reduce the prevalence of dislocation. For any figures or tables, please contact the authors directly

Purpose. To evaluate Radiological changes in the lumbosacral spine after insertion of Wallis Ligament for Foraminal Stenosis. Methods and Results. Thirty two Levels in Twenty Six patients were followed up with standardised radiographs after insertion of Wallis Ligaments for Foraminal Stenosis. Wallis ligaments as a top-off or those with prolapsed discs were not included. The Radiological parameters compared were Anterior and Posterior Disc height, Foraminal height and width, The inter-vertebral angle (IVA), Lumbar lordosis and Scoliosis if any. The presence of slips and their progression post-op was noted, as was bony lysis if any. There were ten males with thirteen levels and sixteen females with nineteen levels in the study. Eighteen levels (56.25%) were L4/L5, ten (31.25%) were L5/S1 and 4 (12.5%)were L3/L4. The average age in the series was 59.6 years (Range 37 – 89 yrs). Average follow up was 9.5 months (Range 2 to 36). The Average increase in Anterior disc height was 1.89 mm (+/−1.39), the posterior disc height increased by an average 1.09 mm (+/−1.14). Foraminal height increased by an average 3.85 mm (+/− 2.72), while foraminal width increased by 2.14 mm (+/− 1.38). The IVA increased in 16 and reduced in 15 patients, with no change in 1. Lumbar Lordosis increased in 23 patients, with an average value of 2.3°. No patient exhibited progression in scoliosis and no lysis could be identified. There were three Grade I slips pre-op; none progressed. Conclusion. Foraminal dimensions and Disc height were consistently improved after Wallis insertion. Changes in IVA and Lumbar lordosis were however variable. A longer follow up is suggested to look for sustained improvement and the presence of lysis. Ethics approval- None, Audit/service standard in trust. Interest statement - None

Introduction. Interactions between hip, pelvis and spine, as abnormal spinopelvic movements, have been associated with inferior outcomes following total hip arthroplasty (THA). Changes in pelvis position lead to a mutual change in functional cup orientation, with both pelvic tilt and rotation having a significant effect on version. Hip osteoarthritis (OA) patients have shown reduced hip kinematics which may place increased demands on the pelvis and the spine. Sagittal and coronal planes assessments are commonly done as these can be adequately studied with anteroposterior and lateral radiographs. However, abnormal pelvis rotation is likely to compromise the outcome as they have a detrimental effect on cup orientation and increased impingement risk. This study aims to determine the association between dynamic motion and radiographic sagittal assessments; and examine the association between axial and sagittal spinal and pelvic kinematics between hip OA patients and healthy controls (CTRL). Methods. This is a prospective study, IRB approved. Twenty hip OA pre-THA patients (11F/9M, 67±9 years) and six CTRL (3F/3M, 46±18 years) underwent lateral spinopelvic radiographs in standing and seated bend-and-reach (SBR) positions. Pelvic tilt (PT), pelvic-femoral-angle (PFA) and lumbar lordosis (LL) angles were measured in both positions and the differences (Δ) between standing and SBR were calculated. Dynamic SBR and seated maximal-trunk-rotation (STR) were recorded in the biomechanics laboratory using a 10-infrared camera and processed on a motion capture system (Vicon, UK). Direct kinematics extracted maximal pelvic tilt (PT. max. ), hip flexion (HF. max. ) and (mid-thoracic to lumbar) spinal flexion (SF. max. ). The SBR pelvic movement contribution (ΔPT. rel. ) was calculated as ΔPT/(ΔPT+ΔPFA)∗100 for the radiographic analysis and as PT. max. /(PT. max. +HF. max. ) for the motion analyses. Axial and sagittal, pelvic and spinal range of motion (ROM) were calculated for STR and SBR, respectively. Spearman's rank-order determined correlations between the spinopelvic radiographs and sagittal kinematics, and the sagittal/axial kinematics. Mann-Whitney U-tests compared measures between groups. Results. Radiograph readings correlated with sagittal kinematics during SBR for ΔPT and PT. max. (ρ=0.64, p<0.001), ΔPFA and HF. max. (ρ=0.44, p<0.0002), and ΔLL and SF. max. (ρ=0.34, p=0.002). Relative pelvic movements (ΔPT. rel. ) were not different between radiographic (11%±21) and biomechanical (15%±29) readings (p=0.9). Sagittal SRB spinal flexion correlated with the axial STR rotation (ρ=0.43, p<0.0001). Although not seen in CTRL, sagittal SRB pelvic flexion strongly correlated with STR pelvic rotation in OA patients (ρ=0.40, p=0.002). All spinopelvic parameters were different between the patients with OA and CTRL. CTRLs exhibited significantly greater mobility and less variability in all 3 segments (spine, pelvis, hip) and both planes (axial and sagittal) (Table 1). Conclusion. Correlation between sagittal kinematics and radiographical measurements during SBR validates the spinopelvic mobility assessments in the biomechanics laboratory. Axial kinematics of both pelvis and spine correlated significantly in OA patients, suggesting that patients with abnormal sagittal mobility are likely to also exhibit abnormal axial mobility, which can further potentiate any at-risk kinematics. Significantly lower OA ROM must be investigated post-THA. Pre-THA variability of both sagittal and axial movements indicates that both planes must be considered ahead of surgical planning with navigation and/or robotics. For any figures or tables, please contact the authors directly

Introduction. Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup. Technique. The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on the 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increased or decreased lumbar lordosis and combined anteversion. Methods. Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using EBRA software. Results. There were no malalignments or dislocations. The mean cup inclination angle and anteversion were 41 ± 5.1 degrees (range 37.1 – 48.4) and 22.1 ± 4.8 degrees (range 16.6 – 29.3), respectively. Conclusion. This is a reproducible method of cup positioning and with proper femoral component position and restoring leg length, offset, combined anteversion, and balance soft tissue around the hip. These factors affect the incidence of dislocation, infection, reduced wear, and durability

INTRODUCTION. Standing spinal alignment has been the center of focus recently, particularly in the setting of adult spinal deformity. Humans spend approximately half of their waking life in a seated position. While lumbopelvic sagittal alignment has been shown to adapt from standing to sitting posture, segmental vertebral alignment of the entire spine is not yet fully understood, nor are the effects of DEGEN or DEFORMITY. Segmental spinal alignment between sitting and standing, and the effects of degeneration and deformity were analyzed. METHODS. Segmental spinal alignment and lumbopelvic alignment (pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), PI-LL, sacral slope) were analyzed. Lumbar spines were classified as NORMAL, DEGEN (at least one level of disc height loss >50%, facet arthropathy, or spondylolisthesis), or DEFORMITY (PI-LL mismatch>10°). Exclusion criteria included lumbar fusion/ankylosis, hip arthroplasty, and transitional lumbosacral anatomy. Independent samples t-tests analyzed lumbopelvic and segmental alignment between sitting and standing within groups. ANOVA assessed these differences between spine pathology groups. RESULTS. There were 183 NORMAL, 216 DEGEN and 92 DEFORMITY patients with significant differences in age, gender, and hip OA grades. After propensity matching for these factors, there were 56 patients in each group (age 63±14, 58% female) [Fig. 1]. Significant differences were noted between spinal pathology groups with regard to changes from standing to sitting alignment with regard to NORMAL vs DEGEN vs DEFORMITY groups in PT (13.93° vs −11.98° vs − 7.95°; p=0.024), LL (21.91° vs 17.45° vs 13.23°; p=0.002), PI-LL (−22.32° vs −17.28° vs −13.18°; p<0.001), SVA (−48.99° vs −29.98° vs −32.12°; p=0.002), and TPA(−16.35° vs −12.69° vs −9.64; p=0.001). TK (−2.08° vs −2.78° vs −2.00°, p=0.943) and CL (−3.84° vs −4.14° vs −3.57°, p=0.621) were not significantly different across spinal pathology groups [Fig. 2]. NORMAL patients had overall greater mobility in the lower lumbar spine from standing to sitting compared to DEGEN and DEFORMITY patients. L4-L5 (7.50° vs 5.23° vs 4.74°, p=0.012) and L5-S1 (6.96° vs 5.28° and 3.69°, p=0.027). There were no significant differences in change in alignment from standing to sitting at the upper lumbar levels or lower thoracic levels between the three groups [Fig. 3]. CONCLUSION. The lower lumbar spine provides the greatest sitting to standing change in lumbopelvic alignment in normal patients. Degeneration and deformity of the spine significantly reduces the mobility of the lower lumbar spine and PT. With lumbar spine degeneration and flatback deformity, relatively more alignment change occurs at the upper lumbar spine and thoracolumbar junction

Introduction: Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup. Technique: The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increase or decrease of lumbar lordosis and combined anteversion. Methods: Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using EBRA software. Results: There were no malalignment or dislocation. The mean cup inclination angle and anteversion were 41 ± 5.1 degrees (range 37.1 – 48.4) and 22.1 ± 4.8 degrees (range 16.6 – 29.3), respectively. Conclusion: This is a reproducible method of cup positioning and with proper femoral component position, restores leg length, offset, combined anteversion, and balances soft tissue around the hip. These factors affect the incidence of dislocation, infection, reduced wear, and durability

Background. Spinal deformity has a known deleterious effect upon the outcomes of total hip arthroplasty and acetabular component positioning. This study sought to evaluate the relationship between severity of spinal deformity parameters and acetabular cup position, rate of dislocation, and rate of revision among patients with total hip arthroplasties and concomitant spinal deformity. Methods. A prospectively collected database of patients with spinal deformity was reviewed and patients with total hip arthroplasty were identified. The full body standing stereoradiographic images (EOS) were reviewed for each patient. From these images, spinal deformity parameters and acetabular cup anteversion and inclination were measured. A chart review was performed on all patients to determine dislocation and revision arthroplasty events. Statistical analysis was performed to determine correlation of deformity with acetabular cup position. Subgroup analysis was performed for patients with spinal fusion, dislocation events, and revision THA. Results. One-hundred and seven spinal deformity patients were identified, with 139 hips for analysis. The rate of THA dislocation in this cohort was 8.0%, with a revision rate of 5.8% for instability. Patients who sustained dislocations had significantly higher spinopelvic tilt, T1-pelvic angle, and mismatch of lumbar lordosis and pelvic incidence. Among all patients, only 68.8% met the radiographic “safe zone” for anteversion in the standing position (Figure 1). A comparison of radiographic cup position on supine x-ray with standing EOS imaging demonstrated an increase in anteversion of 6.2 degrees. Standing decreased rate of safe zone anteversion of the cup by 20%. Conclusions. In this cohort, patients with THA and concomitant spinal deformity have a particularly high rate of dislocation. This dislocation risk may be driven by the degree of spinal deformity and by spinopelvic compensation, which is suggested by our findings. Arthroplasty surgeons should be aware of the elevated dislocation rate and consider a surgical strategy for maintaining hip stability in this population

Purpose. The aim of this study is to describe the influence of sitting and standing posture on sagittal pelvic inclination in preoperative total hip replacement patients to assist with correct acetabular component positioning. Methods. Lateral radiographs of the pelvis and lumbar spine in sitting and standing of preoperative hip arthroplasty patients with primary hip osteoarthritis were extracted. Pelvic tilt was measured using the vertical inclination of a line from the ASIS to pubic tubercle. Sacral inclination was measured as the angle between the anterior surface of the sacrum and a horizontal reference. Figure one is a representation of the pelvic tilt angle and sacrel inclination angle taken during standing. The Cobb angle of the lumbar spine was recorded represented for a sitting patient in figure 2. Hip flexion was recorded (figure 2). Results. 60 patients were identified. Mean age of the cohort was 63. Sacral inclination ranged from 1 to 55 degrees in standing with a mean of 25.7 degrees. In sitting, sacral inclination ranged from 0.3–84.5 degrees with a mean of 24.1 degrees. Pelvic tilt ranged from 30 degrees posteriorly to 21.5 degrees anteriorly in standing. Pelvic tilt in sitting and ranged from 48 posterior to 42 degrees anterior tiltLumbar lordosis ranged from 11.6 to 91.7 degrees in standing. Lumbar lordosis in sitting ranged from 29.5 degrees(kyphosis) to 42 degrees (lordosis). Total hip flexion was 107.4 degrees from standing to sitting. Conclusions. There is wide variability in pelvic orientation between individuals in both postures Orientating acetabular components for total hip arthroplasty should account for postural changes in native version

Purpose. Posterior pelvis tilt (PPT) would affect lumbar lordosis and lead to hip flexion, which causes difficulties walking and standing in patients with hip disorders. Hip flexion movement associated with PPT is well known. We investigated the effect of the angle of hip flexion without the movement of PPT in the supine position. Methods. The study enrolled 24 healthy males with an average age of 20.5 ± 2.3 years. Two pelvic positions in the supine position were investigated: (1) the limited position of the PPT by 500ml PET bottle with water placed under their low back, and (2) the position without placing a PET bottle. We assessed unilateral hip flexion angle with photos taken with a digital camera. For reference, we took an X-ray of a healthy female and observed the lumbo-sacral from the sagittal plane in the supine position. Analysis. Data was processed by Image analysis software (Image J 1.42, NIH). Paired t-tests were used to assess the range of motion of individual joints in each position in the sagittal plane. MEPHAS software (Oosaka University. Japan) was used for all statistical processing, and the level of significance was set at P < 0.05. In addition, we also measured the lumbo-sacral angle (LSA), the lumbo-lordotic angle (LLA) and the sacral slope angle (SSA) with the X-ray. Results. The angle of hip flexion decreased 22.9±6.04 degrees on average in the limited position with a PET bottle compared with the position without a bottle (P<0.01). The angle of pelvis decreased 4.8±2.0 degrees on average. Discussion. The angle of hip flexion significantly decreased in the limited position with a PET bottle. Our results suggest the association movement of the PPT with hip flexion movement in the supine position. This suggests that movements of the LLA and SSA are involved greatly in hip flexion. Significance of study. Our results provide evidence that could lead to more effective way of measurement of the primary hip joint (coxal femoral joint) flexion in the supine position for the patients with hip diseases. If we can measure primary hip joint (coxal femoral joint) flexion, it may also be measured mobility of the pelvis. Measurement of the hip joint flexion should consider the movement of the lumbar vertebrae and the sacral slope

Introduction. In the previous study regarding the relationship among maximum hip flexion, the pelvis, and the lumbar vertebrae on the sagittal plane, we have found in X-rays that the lumbo lordotic angle (LLA) and the sacral slope angle (SSA) have a large impact on hip flexion angle. We examined hip flexion angles to the various height of the objects (half round plastic tube) placed under the subject's lower back and compared the passive hip flexion angles in the supine position between younger and middle age groups. Participants. The participants were 14 healthy volunteers: 7 females with an average age of 17 years (Group 1: G-1), 7 females with an average age of 45 years (Group 2: G-2). The average BMI (Body Mass Index) of volunteers was less than 25, and their Tomas Tests were negative. Methods. The hip flexion angle was measured in six stages as half round plastic tube placed under the subject's lower back gradually increased in height by 5mm. StageZero is the Regular Position with nothing placed under the subject's lower back: RP (specified Japanese Orthopedics Association and Rehabilitation Medical Association). The next five stages (from Stage One) were performed in the Limited Position (LP) of the posterior pelvic tilt and lumbar movement by placing the tube under the subject's lower back. The height of tube is 2.2 cm. Stage One started at 2.2cm. Each Stage from Stage One has a difference in the height of 5mm. Stage Zero: 0cm, Stage 1: 2.2cm, Stage 2: 2.7cm, Stage 3: 3.2cm, Stage 4: 3.7cm, Stage 5: 4.2cm,. Analysis. We compared the hip flexion angle of six stages of the two groups. A two-way repeated measurement ANOVA was used to compare the differences in hip flexion angle of G1 and G2. Statistical significant was established at p < 0.05. Further, we took X-rays of a healthy female and examined the LLA, SSA, and Lumbo Sacral Angle (LSA) during hip maximum flexion. Results & Discussion. In RP (Stage Zero), the LLA and the SSA had a large impact on hip flexion angle observed in X-rays. In Stages1-6, there was a slight movement in the LLA and the SSA. The higher the tubes’ height, the smaller the hip flexion angle. When the height was low, the posterior pelvic tilt became large, resulting in a larger hip flexion angle. The fulcrum rotational point of the hip flexion would move to the lumbar side. We need to determine and tailor the height of object to each individual lumbar lordosis

Introduction. Pedicle subtraction osteotomy is a powerful technique for correcting sagittal imbalance in ankylosing spondylitis. There has been significant perioperative morbidity associated with this technique in the peer review literature. We present the Royal National Orthopaedic Hospital experience with a single surgeon retrospective study that was conducted to evaluate the outcomes in patients who underwent lumbar pedicle subtraction osteotomy for the correction of thoracolumbar kyphotic deformity in ankylosing spondylitis. Method. Twenty seven patients underwent a lumbar pedicle subtraction osteotomy and adjacent level posterior instrumentation between 1995 and 2010. There were 18 males and 9 females in the study. Events during the peri-operative course and post-operative complications were recorded. The radiological outcome and patient satisfaction were analysed with mean follow-up of one and a half years. Results. The mean operative time was three and half hours and the mean blood loss was 2290mls. Final follow-up radiograph showed an increase in lumbar lordosis angle from 17 degrees to 45 degrees. The sagittal imbalance improved by 85mm with the operation. Complications included loosening in two patients, one transient neurologic deficit and one infective non-union occurred overall. There were no mortalities from the surgery. Two patients developed junctional kyphosis and required a repeat operation. There was an improvement in the Oswestry Disability Score from a mean of 29 to 16 after the surgey. All (100%) of the patients were satisfied with the results of the procedure and would recommend the surgey to others. Conclusion. The study shows that pedicle subtraction extension osteotomy is effective for the correction of kyphotic deformity in ankylosing spondylitis

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