PI-LL Mismatch Research Articles

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

Pelvic incidence (PI) is a position-independent spinopelvic parameter traditionally used by spinal surgeons to determine spinal alignment. Its relevance to the arthroplasty surgeon in assessing patient risk for total hip arthroplasty (THA) instability preoperatively is unclear. This study was undertaken to investigate the significance of PI relative to other spinopelvic parameter risk factors for instability to help guide its clinical application. Retrospective analysis was performed of a multicentre THA database of 9,414 patients with preoperative imaging (dynamic spinopelvic radiographs and pelvic CT scans). Several spinopelvic parameter measurements were made by engineers using advanced software including sacral slope (SS), standing anterior pelvic plane tilt (APPT), spinopelvic tilt (SPT), lumbar lordosis (LL), and PI. Lumbar flexion (LF) was determined by change in LL between standing and flexed-seated lateral radiographs. Abnormal pelvic mobility was defined as ∆SPT ≥ 20° between standing and flexed-forward positions. Sagittal spinal deformity (SSD) was defined as PI-LL mismatch > 10°. PI showed a positive correlation with parameters of SS, SPT, and LL (r-value range 0.468 to 0.661). Patients with a higher PI value showed higher degrees of standing LL, likely as a compensatory measure to maintain sagittal spine balance. There was a positive correlation between LL and LF such that patients with less standing LL had decreased LF (r = 0.49). Similarly, there was a positive correlation between increased SSD and decreased LF (r = 0.54). PI in isolation did not show any significant correlation with lumbar (r = 0.04) or pelvic mobility (r = 0.02). The majority of patients (range 89.4% to 94.2%) had normal lumbar and pelvic mobility regardless of the PI value. The PI value alone is not indicative of either spinal or pelvic mobility, and thus in isolation may not be a risk factor for THA instability. Patients with SSD had higher rates of spinopelvic stiffness, which may be the mechanism by which PI relates to THA instability risk, but further clinical studies are required. Cite this article: Bone Joint J2022;104-B(3):352-358.

Transforaminal lumbar interbody fusion with a silicon nitride cage demonstrates early radiographic fusion.

Degeneration of the lumbar spine is common in aging adults and reflects a significant morbidity burden in this population. In selected patients that prove unresponsive to non-surgical treatment, posterior lumbar fusion (PLF) surgery, with or without adjunctive transforaminal lumbar interbody fusion (TLIF) can relieve pain and improve function. We describe here the radiographic fusion rates for PLF versus TLIF, using an intervertebral spinal cage made of silicon nitride ceramic (chemical formula Si3N4). This retrospective cohort analysis enrolled 99 patients from August 2013 to January 2017; 17 had undergone PLF at 24 levels, while 82 had undergone TLIF at 104 levels. All operations were performed by a single surgeon at one institution. Radiographic and clinical outcomes were compared between PLF and TLIF at 2 and 6 weeks and then at 3, 6, 12, and 24 months. TLIF patients fused at higher rates compared to PLF at the 3-month (38.5% vs. 8.3%, P=0.006), 6-month (78.7% vs. 35.0%, P<0.001) and 12-month time periods (97.9% vs. 81.3%, P=0.018), with no difference at 24 months (100% vs. 94.4%, P=0.102). Index level segmental motion was significantly less and intervertebral disc height was improved in TLIF over PLF at all follow up intervals. Foraminal height was only greater in early follow up periods (2 weeks, 6 weeks and 3 months). TLIF patients experienced lover rates of PI-LL mismatch which was maintained across long term follow-up. Pelvic tilt was lower following TLIF compared to PLF, with no differences in complication rates between study groups. Our retrospective series demonstrated that TLIF performed with silicon nitride interbody cages led to earlier radiographic fusion, greater restoration of disc and foraminal height, increased segmental rigidity and improved sagittal alignment when compared to PLF alone.

Impact of sarcopenia and sagittal parameters on the residual back pain after percutaneous vertebroplasty in patients with osteoporotic vertebral compression fracture

ObjectiveThe objective of this study was to explore the impact of sarcopenia and sagittal parameters on the residual back pain (RBP) after percutaneous vertebroplasty (PVP) for treatment of osteoporotic vertebral compression fracture (OVCF).MethodsThis retrospective study included elderly patients (age range 60–90 years) with OVCF treated with PVP from January 2015 and December 2020 in our hospital. The skeletal muscle mass index (SMI) was calculated by dividing the T12 pedicle level muscle cross-sectional area by the square of body height from chest CT to diagnose sarcopenia. The radiological parameters for measuring the sagittal alignment were included: C7-sagittal vertical axis (SVA), T1 pelvic angle (TPA), lumbar lordosis (LL), thoracic kyphosis (TK), pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI).ResultAccording to whether the VAS score > 4, patients were divided into RBP group (56 patients) and Control group (100 patients). There was no difference in age, gender, body mass index, BMD, surgical segment, bone cement usage between the groups (P > 0.05). The SMI in RBP group (27.3 ± 5.1) was significantly lower compared to that in Control group (36.8 ± 3.2) (P < 0.05). Sarcopenia was present in 19 patients (20.3%) in RBP group, which was significantly more than that in Control group (P < 0.05). C7-SVA and TPA was significantly larger in the RBP group than in the Control group (P < 0.05). PI and LL was significantly smaller in the RBP group compared to the Control group (P < 0.05). However, no significant differences between the two groups with respect to TK, SS and PT (P > 0.05).ConclusionPoor sagittal parameters and sarcopenia in OVCF patients after PVP were more prone to residual back pain. Larger C7-SVA, TPA and PI-LL mismatch could increase the incidence of RBP in elderly patients with single-segment osteoporotic compression fractures.

Relation significative entre l’incidence pelvienne et la lordose lombaire debout, et la flexibilité lombaire chez les patients japonais atteints d’arthrose de la hanche : une étude radiographique descriptive

IntroductionSpine stiffness is known to increase the risk of total hip replacement (THR) instability. The sagittal posture and lumbo-pelvic kinematics have therefore become parameters of interest when planning THR. We conducted this study to investigate (1) the distribution and characteristics of the spino-pelvic standing alignment, (2) the relationship between pelvic incidence (PI) and standing lumbar lordosis (LL) and lumbar flexibility, in Japanese hip osteoarthritis patients. Hypothesis(1) Japanese hip osteoarthritis patients with different sagittal spino-pelvic alignments do not differ markedly in their demographics, PI, or lumbar flexibility; and (2) there is no significant relationship between PI, standing LL, and lumbar flexibility in a population of Japanese hip osteoarthritis patients. Material and methodsA retrospective study of radiographs from 945 Japanese patients who consecutively received THR for the treatment of hip osteoarthritis. All patients preoperatively underwent lateral standing and deep-seated lumbo-pelvic radiography on which the spino-pelvic parameters were measured. The difference between the standing and deep-seated LL angles defined the lumbar flexibility and was calculated as the delta (Δ) LL. Individual spino-pelvic standing alignment was stratified based on the difference between the PI and standing LL (‘PI-LL mismatch’). ‘PI-LL mismatch’ of<−10°, between −10° and 10°, and>10° was defined as hyperlordosis, normolordosis, and flatback, respectively. ResultsIn the present study, the spinal alignment of 115/945 (12.2%), 559/945 (59.2%), and 271/945 (28.6%) patients were classified as hyperlordosis, normolordosis, and flatback, respectively. Hyperlordotic patients had significantly lower PI (47.6°±7.8° vs. 52.7°±10.5°, p<0.001) and higher ΔLL (60.6°±12.6° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. Patients with flatback were significantly older (age, 69.1±9.1years vs. 62.7±9.8years, p<0.001) with higher PI (56.9°±11.7° vs. 52.7°±10.5°, p<0.001) and lower ΔLL (35.2°±17.4° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. A significant relationship between PI and the standing LL was found in the whole cohort (r=0.409, p=0.009), hyperlordotic (r=0.785, p<0.001), normolordotic (r=0.857, p<0.001), and flatback (r=0.664, p<0.001) patients. Significant relationships between the PI and ΔLL were also found in normolordotic (r=0.442, p=0.004) and flatback (r=0.449, p=0.003) patients but not hyperlordotic patients (r=0.154, p=0.367). DiscussionA large proportion of Japanese hip osteoarthritis patients have abnormal PI-LL mismatch (12% and 29% have hyperlordosis and flatback, respectively). The PI was a determinant of the standing LL, and the standing LL was a strong determinant of the lumbar flexibility, especially in the normolordotic and hyperlordotic individuals. Level of evidenceIII; retrospective diagnostic radiographic study.

Long-term Outcomes of Minimally Invasive Lateral Lumbar Interbody Fusion in the Treatment of Adult Scoliosis.

The literature has shown the importance of long-term follow-up for adults with scoliosis treated surgically because complication and revision rates are high. The goal of this study was to determine long-term outcomes and complications of lateral lumbar interbody fusion (LLIF) with posterior instrumentation for adult patients with scoliosis. A retrospective review of our institution's database was performed to identify adult patients with scoliosis treated with LLIF between 2008 and 2013 with a minimum follow-up of 4 years. Medical records were reviewed for complications and revisions. Pre- and postoperative deformity Cobb angle measurements were taken as well as pelvic incidence (PI) and lumbar lordosis (LL). Functional outcome scores, including Oswestry Disability Index and visual analog scale score for back and leg pain, were assessed preoperatively and at follow-up. Standard binomial and categorical comparative analysis was performed. The 26 patients included had a mean age of 62 years, mean follow-up of 89 months, and mean of 1.8 levels per operation. Four patients (15.4%) required revisions. Mean deformity Cobb angle was 26° preoperatively and 14° postoperatively. Mean PI-LL mismatch was 11.7° preoperatively and 5.9° postoperatively. Nineteen (73%) patients had a PI-LL mismatch greater than 10° preoperatively, whereas only 2 (7.7%) had a mismatch postoperatively. Improvement was seen in all functional outcome scores. Long-term clinical results of LLIF for adults with deformity showed a low proportion of revision in the treatment of a condition with an established high rate of revision. The ability to reduce pelvic mismatch may further reduce the rate of revision. In this study, LLIF resulted in improved functional outcomes and patient satisfaction. [Orthopedics. 2022;45(3):e134-e139.].

Alteration of the Sitting and Standing Movement in Adult Spinal Deformity.

Adults with spinal deformity (ASD) are known to have spinal malalignment affecting their quality of life and daily life activities. While walking kinematics were shown to be altered in ASD, other functional activities are yet to be evaluated such as sitting and standing, which are essential for patients’ autonomy and quality of life perception. In this cross-sectional study, 93 ASD subjects (50 ± 20 years; 71 F) age and sex matched to 31 controls (45 ± 15 years; 18 F) underwent biplanar radiographic imaging with subsequent calculation of standing radiographic spinopelvic parameters. All subjects filled HRQOL questionnaires such as SF36 and ODI. ASD were further divided into 34 ASD-sag (with PT > 25° and/or SVA >5 cm and/or PI-LL >10°), 32 ASD-hyperTK (with only TK >60°), and 27 ASD-front (with only frontal malalignment: Cobb >20°). All subjects underwent 3D motion analysis during the sit-to-stand and stand-to-sit movements. The range of motion (ROM) and mean values of pelvis, lower limbs, thorax, head, and spinal segments were calculated on the kinematic waveforms. Kinematics were compared between groups and correlations to radiographic and HRQOL scores were computed. During sit-to-stand and stand-to-sit movements, ASD-sag had decreased pelvic anteversion (12.2 vs 15.2°), hip flexion (53.0 vs 62.2°), sagittal mobility in knees (87.1 vs 93.9°), and lumbar mobility (L1L3-L3L5: −9.1 vs −6.8°, all p < 0.05) compared with controls. ASD-hyperTK showed increased dynamic lordosis (L1L3–L3L5: −9.1 vs −6.8°), segmental thoracic kyphosis (T2T10–T10L1: 32.0 vs 17.2°, C7T2–T2T10: 30.4 vs 17.7°), and thoracolumbar extension (T10L1–L1L3: −12.4 vs −5.5°, all p < 0.05) compared with controls. They also had increased mobility at the thoracolumbar and upper-thoracic spine. Both ASD-sag and ASD-hyperTK maintained a flexed trunk, an extended head along with an increased trunk and head sagittal ROM. Kinematic alterations were correlated to radiographic parameters and HRQOL scores. Even after controlling for demographic factors, dynamic trunk flexion was determined by TK and PI-LL mismatch (adj. R 2 = 0.44). Lumbar sagittal ROM was determined by PI-LL mismatch (adj. R 2 = 0.13). In conclusion, the type of spinal deformity in ASD seems to determine the strategy used for sitting and standing. Future studies should evaluate whether surgical correction of the deformity could restore sitting and standing kinematics and ultimately improve quality of life.

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

Loss of lumbar lordosis (LL) in degenerative deformity activates spinal compensatory mechanisms to maintain neutral C7 sagittal vertical axis (C7SVA), such as an increase in pelvic tilt (PT) and decreased thoracic kyphosis (TK). We study the extent to which PT increase and TK reduction contribute to the compensation of pelvic incidence (PI)-LL mismatch. A cohort of 43 adult patients with adult degenerative thoracolumbar deformity were included in this retrospective study. Radiographic spinopelvic measurements were obtained before and after corrective surgery. Pearson correlations were calculated. Preoperative PI-LL mismatch significantly correlated with an increase in PT and a decrease in TK in the whole cohort r = +0.66 (95% confidence interval [CI] 0.44-0.8) and r = -0.67 (95% CI - 0.81--0.47), respectively, at a relative rate of 0.37 (standard deviation [SD]: 0.07) and - 0.57 (SD: 0.09), respectively. In patients with low PI, only TK showed a significant correlation with PI-LL mismatch, r = -0.56 (95% CI - 0.8 to - 0.16), at a rate of - 0.57 (SD: 0.19). The high PI subgroup showed a significant correlation with PT, TK, and C7SVA, r = 0.62 (95% CI 0.26-0.82), r = -0.8 (95% CI - 0.9--0.58), and r = 0.71 (95% CI 0.41-0.87) at rates of 0.48 (SD: 0.11), -0.72 (SD: 0.12), and 0.62 (SD: 1.27). Decreased TK represented a more consistent compensatory mechanism in patients with high and low PI when compared to an increase in PT. PI-LL mismatch induced more pronounced changes in TK than did PT in both subgroups. Patients with high PI relied more on increases in PT and a relative decrease in TK to compensate for PI-LL mismatch than patients with low PI.

Sagittal Spinal Deformity in Patients with Idiopathic Normal Pressure Hydrocephalus.

To measure the baseline spinopelvic parameters and characterize the sagittal, and coronal plane deformities in patients with idiopathic normal pressure hydrocephalus (iNPH). We analyzed a series of patients at one academic institution who underwent ventriculoperitoneal shunting for iNPH with pre-shunt standing full length x-rays. The series of patients was enrolled consecutively to minimize selection bias. We quantified comorbid sagittal plane spinal deformity based on the Scoliosis Research Society-Schwab classification system by assessing pelvic incidence and lumbar lordosis mismatch (PI-LL), pelvic tilt (PT), and sagittal vertical axis (SVA). Seventeen patients (59% male) were included in this study. Mean (± standard deviation) age was 74 ± 5.3 years with a body mass index (BMI) of 30 ± 4.5 kg/m < sup > 2< sup > . Six patients (35%) had marked sagittal plane spinal deformity by at least one parameter: five (29%) had greater than 20˚ PI-LL mismatch, three (18%) had > 9.5 cm SVA, and one (6%) had PT greater than 30˚. Additionally, the thoracic kyphosis exceeded the lumbar lordosis in nine patients (53%). Positive sagittal balance, with thoracic kyphosis exceeding lumbar lordosis, is common in iNPH patients. This may lead to postural instability, especially in patients whose gait does not improve following shunting. These patients may warrant further investigation and workup, including full length standing x-rays. Future studies should assess for improvement in the sagittal plane parameters following shunt placement.

Spinopelvic Hypermobility Corrects After Staged Bilateral Total Hip Arthroplasty.

Background: Spinopelvic hypermobility may be secondary to a stiff osteoarthritic hip with a compliant spine. Purpose: We sought to determine if spinopelvic hypermobility resolves after total hip arthroplasty (THA) and when it resolves in patients with bilateral hip osteoarthritis (OA) undergoing staged bilateral THA. We also sought to analyze the change in spinopelvic parameters before and after the second THA. Methods: We conducted a retrospective review of 2047 THAs that were performed by 2 fellowship-trained arthroplasty surgeons from 2014 to 2018. Patients with preoperative spinopelvic hypermobility undergoing staged bilateral THA were identified. Radiographic spinopelvic parameters, including sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative, 6-week postoperative, and 1-year postoperative lateral standing and sitting radiographs. Bilateral hip OA was graded using Kellgren-Lawrence criteria. Results: We identified 42 patients with preoperative spinopelvic hypermobility who underwent staged bilateral THA. Mean time (standard deviation) between surgeries was 9.4 months (±10.0). After the first THA, spinopelvic hypermobility resolved in 29% of the patients. After the second THA, it resolved in 67% at 6 weeks, increasing to 98% at 1 year postoperatively. Conclusion: Spinopelvic hypermobility resolves after staged bilateral THA in 98% of the patients, occurring most often only after the second THA. Less than one-third of the patients had resolution after the first THA, suggesting that contralateral hip OA continues to drive hip-driven spinopelvic motion. Acetabular component position targets based on functional pelvic position should incorporate these changes in spinopelvic motion with the understanding that resolution of hypermobility usually occurs after the second THA.

Does obesity affect acetabular cup position, spinopelvic function and sagittal spinal alignment? A prospective investigation with standing and sitting assessment of primary hip arthroplasty patients

BackgroundTotal hip arthroplasty (THA) instability is influenced by acetabular component positioning, spinopelvic function and sagittal spinal alignment. Obesity is considered as a risk factor of THA instability, but the causal relationship remains unknown. This study aimed to investigate the influence of BMI on (1) spinopelvic function (lumbar flexibility, pelvic mobility and hip motion), (2) sagittal spinal alignment pre- and postoperatively and (3) acetabular cup position postoperatively in primary THA patients in a prospective setting.MethodsOne hundred ninety patients receiving primary total hip arthroplasty were enrolled in a prospective cohort study and retrospectively analysed. All patients received stereoradiography (EOS) in standing and relaxed sitting position pre-and postoperatively. C7-sagittal vertical axis (C7-SVA), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), anterior plane pelvic tilt (APPT), and pelvic femoral angle (PFA) were assessed. Key parameters of the spinopelvic function were defined as lumbar flexibility (∆ LL = LLstanding − LLsitting), pelvic mobility (∆ PT = PTstanding − PTsitting) and hip motion (∆ PFA = PFAstanding − PFAsitting). Pelvic mobility was further defined based on ∆ PT as stiff, normal and hypermobile (∆ PT < 10°; 10°–30°; > 30°). The patients were stratified to BMI according to WHO definition: normal BMI ≥ 18.5–24.9 kg/m2 (n = 68), overweight ≥ 25.0–29.9 kg/m2 (n = 81) and obese ≥ 30–39.9 kg/m2 (n = 41). Post-hoc analysis according to Hochberg's GT2 was applied to determine differences between BMI groups.ResultsStanding cup inclination was significant higher in the obese group compared to the normal BMI group (45.3° vs. 40.1°; p = 0.015) whereas standing cup anteversion was significantly decreased (22.0° vs. 25.3°; p = 0.011). There were no significant differences for spinopelvic function key parameter lumbar flexibility (∆ LL), pelvic mobility (∆ PT) and hip motion (∆ PFA) in relation to BMI stratified groups. The obese group demonstrated significant enhanced pelvic retroversion compared to the normal BMI group (APPT − 1.8° vs. 2.4°; p = 0.028). The preoperative proportion of stiff pelvic mobility was decreased in the obese group (12.2%) compared to normal (25.0%) and overweight (27.2%) groups. Spinal sagittal alignment in C7-SVA and PI-LL mismatch demonstrated significantly greater imbalance in the obese group compared to the normal BMI group (68.6 mm vs. 42.6 mm, p = 0.002 and 7.7° vs. 1.2°, p = 0.032, respectively) The proportion of patients with imbalanced C7-SVA was higher in the obese (58.5%) than in the normal BMI group (44.1%).ConclusionsThe significantly increased spinal sagittal imbalance with altered pelvic mechanics is a potential cause for the reported increased risk of THA dislocations in obese patients. Consequently, the increased spinal sagittal imbalance in combination with normal pelvic mobility need to be taken into account when performing THA in obese patients.

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

IntroductionSpine stiffness is known to increase the risk of total hip replacement (THR) instability. The sagittal posture and lumbo-pelvic kinematics have therefore become parameters of interest when planning THR. We conducted this study to investigate (1) the distribution and characteristics of the spino-pelvic standing alignment, (2) the relationship between pelvic incidence (PI) and standing lumbar lordosis (LL) and lumbar flexibility, in Japanese hip osteoarthritis patients. Hypothesis(1) Japanese hip osteoarthritis patients with different sagittal spino-pelvic alignments do not differ markedly in their demographics, PI, or lumbar flexibility; and (2) there is no significant relationship between PI, standing LL, and lumbar flexibility in a population of Japanese hip osteoarthritis patients. Material and MethodsA retrospective study of radiographs from 945 Japanese patients who consecutively received THR for the treatment of hip osteoarthritis. All patients pre-operatively underwent lateral standing and deep-seated lumbo-pelvic radiography on which the spino-pelvic parameters were measured. The difference between the standing and deep-seated LL angles defined the lumbar flexibility and was calculated as the delta (Δ) LL. Individual spino-pelvic standing alignment was stratified based on the difference between the PI and standing LL (‘PI-LL mismatch’). ‘PI-LL mismatch’ of<−10°, between −10° and 10°, and>10° was defined as hyperlordosis, normolordosis, and flatback, respectively. ResultsIn the present study, the spinal alignment of 115/945 (12.2%), 559/945 (59.2%), and 271/945 (28.6%) patients were classified as hyperlordosis, normolordosis, and flatback, respectively. Hyperlordotic patients had significantly lower PI (47.6°±7.8° vs. 52.7°±10.5°, p<0.001) and higher ΔLL (60.6°±12.6° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. Patients with flatback were significantly older (age, 69.1±9.1 years vs. 62.7±9.8 years, p<0.001) with higher PI (56.9°±11.7° vs. 52.7°±10.5°, p<0.001) and lower ΔLL (35.2°±17.4° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. A significant relationship between PI and the standing LL was found in the whole cohort (r=0.409, p=0.009), hyperlordotic (r=0.785, p<0.001), normolordotic (r=0.857, p<0.001), and flatback (r=0.664, p<0.001) patients. Significant relationships between the PI and ΔLL were also found in normolordotic (r=0.442, p=0.004) and flatback (r=0.449, p=0.003) patients but not hyperlordotic patients (r=0.154, p=0.367). DiscussionA large proportion of Japanese hip osteoarthritis patients have abnormal PI-LL mismatch (12% and 29% have hyperlordosis and flatback, respectively). The PI was a determinant of the standing LL and the lumbar flexibility, especially in the normolordotic and flatback individuals. Level of EvidenceIII; retrospective diagnostic radiographic study.

Single position lateral decubitus anterior lumbar interbody fusion (ALIF) and posterior fusion reduces complications and improves perioperative outcomes compared with traditional anterior-posterior lumbar fusion

BACKGROUND CONTEXTLateral decubitus single position anterior-posterior (AP) fusion utilizing anterior lumbar interbody fusion and percutaneous posterior fixation is a novel, minimally invasive surgical technique. Single position lumbar surgery (SPLS) with anterior lumbar interbody fusion (ALIF) or lateral lumbar interbody fusion (LLIF) has been shown to be a safe, effective technique. This study directly compares perioperative outcomes of SPLS with lateral ALIF vs. traditional supine ALIF with repositioning (FLIP) for degenerative pathologies. PURPOSETo determine if SPLS with lateral ALIF improves perioperative outcomes compared to FLIP with supine ALIF. STUDY DESIGN/SETTINGMulticenter retrospective cohort study. PATIENT SAMPLEPatients undergoing primary AP fusions with ALIF at 5 institutions from 2015 to 2020. OUTCOME MEASURESLevels fused, inclusion of L4-L5, L5-S1, radiation dosage, operative time, estimated blood loss (EBL), length of stay (LOS), perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), and PI-LL mismatch. METHODSRetrospective analysis of primary ALIFs with bilateral percutaneous pedicle screw fixation between L4-S1 over 5 years at 5 institutions. Patients were grouped as FLIP or SPLS. Demographic, procedural, perioperative, and radiographic outcome measures were compared using independent samples t-tests and chi-squared analyses with significance set at p <.05. Cohorts were propensity-matched for demographic or procedural differences. RESULTSA total of 321 patients were included; 124 SPS and 197 Flip patients. Propensity-matching yielded 248 patients: 124 SPLS and 124 FLIP. The SPLS cohort demonstrated significantly reduced operative time (132.95±77.45 vs. 261.79±91.65 min; p <0.001), EBL (120.44±217.08 vs. 224.29±243.99 mL; p <.001), LOS (2.07±1.26 vs. 3.47±1.40 days; p <.001), and rate of perioperative ileus (0.00% vs. 6.45%; p =.005). Radiation dose (39.79±31.66 vs. 37.54±35.85 mGy; p =.719) and perioperative complications including vascular injury (1.61% vs. 1.61%; p =.000), retrograde ejaculation (0.00% vs. 0.81%, p =.328), abdominal wall (0.81% vs. 2.42%; p =.338), neuropraxia (1.61% vs. 0.81%; p =.532), persistent motor deficit (0.00% vs. 1.61%; p =.166), wound complications (1.61% vs. 1.61%; p =.000), or VTE (0.81% vs. 0.81%; p =.972) were similar. No difference was seen in 90-day return to OR. Similar results were noted in sub-analyses of single-level L4-L5 or L5-S1 fusions. On radiographic analysis, the SPLS cohort had greater changes in LL (4.23±11.14 vs. 0.43±8.07 deg; p =.005) and PI-LL mismatch (-4.78±8.77 vs. -0.39±7.51 deg; p =.002). CONCLUSIONSSingle position lateral ALIF with percutaneous posterior fixation improves operative time, EBL, LOS, rate of ileus, and maintains safety compared to supine ALIF with prone percutaneous pedicle screws between L4-S1.

Clinical, Radiographic, and Genetic Analyses in a Population-Based Cohort of Adult Spinal Deformity in the Older Population.

ObjectiveThis study aimed to identify the sagittal parameters associated with health-related quality of life and genetic variations that increase the risk of adult spinal deformity (ASD) onset in the older population. MethodsWe recruited 120 participants who had a sagittal vertical axis > 50 mm in a sagittal imbalance study. Sagittal radiographic parameters, cross-sectional area, and intramuscular fatty infiltration using the Goutallier classification in the paraspinal lumbar muscles were evaluated. Functional scales included the self-reported Oswestry Disability Index (ODI), 36-item Short Form Health Survey (SF-36), and visual analogue scales (VAS) for back and leg pain. We performed whole-exome sequencing and an exome-wide association study using the 100 control subjects and 63 individuals with severe phenotypes of sagittal imbalance. ResultsPelvic incidence minus lumbar lordosis (PI–LL) mismatch was negatively associated with the SF-36 and positively correlated with ODI and VAS for back and leg pain. PI–LL was related to the quality and size of the paraspinal muscles, especially the multifidus muscle. We identified common individual variants that reached exome-wide significance using single-variant analysis. The most significant single-nucleotide polymorphism was rs78773460, situated in an exon of the SVIL gene (odds ratio, 9.61; p=1.15 × 10-9). ConclusionOlder age, higher body mass index, and a more significant PI–LL mismatch were associated with unfavorable results on functional scales. We found a genetic variation in the SVIL gene, which has been associated with the integrity of the cytoskeleton and the development of skeletal muscles, in severe ASD phenotypes. Our results help to elucidate the pathogenesis of ASD.

脆弱性骨盤骨折患者における脊椎骨盤アライメントと骨折の進展の関係

【目的】脆弱性骨盤骨折（FFP）における骨折の進展は臨床的に問題になっている．しかしながら，脊椎骨盤アライメントと骨折の進展の関係に関する報告はない．本研究の目的は，FFPにおける脊椎骨盤アライメントと骨折の進展との関連性を調査することである．【方法】2017年1月から2019年12月に立位全脊柱・骨盤X線側面像を撮影したFFP28例を対象とした後方視的研究である．初診時と最終フォローアップ時の画像検査より，骨折の進展あり群（n＝14）と進展なし群（n＝14）に分類し，脊椎骨盤アライメント（PI，PT，SS，LL，TK，SVA，PI-LL mismatch）を比較した．【結果】進展あり群と進展なし群との間で，PI（68.9° vs. 68.5°，p＝0.938），PT（35.2° vs. 33.5°，p＝0.737），SS（33.1° vs. 35.0°，p＝0.633），LL（25.0° vs. 32.1°，p＝0.189），TK（49.0° vs. 50.5°，p＝0.849），SVA（105.2mm vs. 97.3mm，p＝0.670），PI-LL mismatch（44.0° vs. 36.4°，p＝0.332）は有意差を認めなかった．【考察】FFPにおける脊椎骨盤アライメントと骨折の進展との関連性は認めなかった．今後は症例数を増やして検討する必要がある．

Minimally Invasive Interlaminar Decompression with a 10-mm Endoscope and Microscope in Cases of Adult Degenerative Scoliosis

Adult degenerative (de novo) scoliosis (ADS) usually occurs due to degenerative changes and is accompanied by progressive low-back pain and/or symptomatic lumbar stenosis. Interlaminar decompression is considered an effective treatment of lumbar stenosis, but some surgical contraindications to traditional open surgery limit its application in elderly patients with many disorders. A 10-mm endoscope has been used in the treatment of stenosis in individuals with ADS and its safety and efficacy should be assessed. The objective was to conduct a retrospective analysis to compare interlaminar decompression with a 10-mm endoscope versus a microscope. Retrospective study. This study took place at the First Affiliated Hospital of Harbin Medical University. The data of 34 ADS patients treated in our hospital from January 2018 to December 2019, who underwent decompression with a 10-mm endoscope (ES group, 19 patients) or microscope (MS group, 15 patients) were retrospectively reviewed. The two methods were compared using the visual analog scale (VAS), Japanese orthopedic association (JOA) scale, and Oswestry disability index (ODI). Lumbar stability was also evaluated by the progression of scoliosis. There were no significant differences between the 2 groups in demographic or clinical characteristics. The mean preoperative Cobb angle of all patients was 23.34° ± 6.44°, which indicated degenerative scoliosis. The mean JOA and ODI scores were 8.09 ± 1.44 and 55.47 ± 11.91. The mean preoperative pelvic incidence (PI) and lumbar lordosis (LL) angles were 51.02° ± 7.21 and 38.26° ± 6.98 and the mean PI-LL mismatch was 12.76° ± 5.63. There was no significant difference in the VAS scores for back/leg pain between the groups at 1 week after the operation, but the scores of the ES group were significantly higher than those of the MS group at 3 months and 12 months. There were no significant differences of mean JOA and ODI between the ES and MS groups preoperatively, at 3 months, or at 12 months, but the JOA and ODI scores of the ES group were significantly higher than those of the MS group 1 week after the operation. The study showed that a novel method for the minimally invasive treatment of ADS is feasible; the safety and outcomes of this method should be verified with more cases. Minimally invasive decompression with a 10-mm endoscope was suggested to be a safe and effective method, as expected, for the treatment of lumbar stenosis in ADS patients.

Reproducibility and Accuracy of Pelvic Tilt in Predicting the Difference Between Pelvic Incidence and Lumbar Lordosis Value

We investigated the pelvic morphologic factors that determine the degree of pelvic incidence (PI)-lumbar lordosis (LL) mismatch. Overall, 306 patients were included. The regional and global sagittal parameters were measured. Linear regression analyses were performed for 4 pelvic parameters and PI-LL mismatch. E1 and E2 were defined as linear regression equations between pelvic tilt (PT) and PI-LL mismatch and PI and PI-LL mismatch, respectively. The patients were categorized by cluster analysis using the hierarchal method for the 4 pelvic parameters. E1 and E2 showed statistical significance; however, the coefficient of determination of E1 was higher than that of E2 (R2= 0.675 vs. 0.238; P < 0.01). Sex, LL, E1, and E2 showed significant differences in the regional parameters. The T1 pelvic angle (TPA), spinosacral angle (SSA), and incidence angle of inflection points (IAIPs) showed significant differences in global parameters (P < 0.01). The IAIPs and TPA were low in the anteverted pelvis group and high in the retroverted pelvis group (P < 0.001). The SSA was low inthe small pelvis group and high in the large pelvis group (P< 0.001). The proportion of women in the large pelvis group (93%) was significantly higher than that in the other groups (P < 0.01). The individual differences between the PI and LL values can be more accurately determined using the individual PT, and the optimal PT amount will differ depending on the pelvis shape. The increase in the TPA and IAIPs corresponded to the PT, and the SSA increased in accordance with the pelvic size.

Does timing of lumbar fusion affect dislocation rate after total hip arthroplasty?

IntroductionThe impact of lumbar spinal fusion (LSF) on pelvic mobility and increased risk for THA dislocation are recognized. However, there is still controversy on whether THA should be performed prior or following LSF. This study aims to compare the rates of hip dislocation in patients undergoing THA prior to or following LSF. MethodsWe retrospectively reviewed 109 primary THA and LSF. There were 34 men and 75 women with a mean age of 66.9. The cohort was divided into 2 groups: 1) THA prior to lumbar fusion (n = 42) and 2) THA following lumbar fusion (n = 67). Radiographic parameters including acetabular component abduction, anteversion, pelvic incidence (PI), sacral slope, standing lumbar lordosis (LL) and PI-LL mismatch were determined for each patient. The surgical approach and THA parameters were also recorded and compared between the 2 groups. Patients with fracture, malignant disease, and prior hip hardware were excluded. ResultsThe mean follow up was 14.7 months. Overall, 8 patients (7.3%) had a postoperative hip dislocation (0 in group 1 (0%), and 8 in group 2 (11.9%) (p = 0.022). The mean cup abduction and anteversion in patients that dislocated was 37.7° and 23.4° respectively while patients who did not dislocate had an average cup abduction of 37.6° (p = 0.970) and anteversion of 25.9° (p = 0.367). Patients who dislocated had decreased lumbar lordosis (p = 0.022) and higher PI-LL mismatch (p = 0.0004) compared to that did not dislocate. There were no other significant differences in the spinopelvic parameters between the 2 groups. Neither surgical approach nor dual mobility articulations use had a significant impact on postoperative dislocations. ConclusionHigher rates of hip dislocation were observed in patients undergoing primary THA following LSF. Dislocators had decreased lumbar lordosis and increased PI-LL mismatch. Patients who require both spinal fusion and THA should undergo hip arthroplasty first to minimize the risk of postoperative instability.

Adult spinal deformity surgery: posterior three-column osteotomies vs anterior lordotic cages with posterior fusion. Complications, clinical and radiological results. A systematic review of the literature.

The aim of our study is to analyse mid- to long-term severe adult spinal deformity (ASD) surgery outcomes by comparing three-column osteotomies (3CO) and multiple anterior interbody fusion cages (AC). The PRISMA flowchart was used to systematically review the literature. Only articles with a minimum 24-month follow-up were examined, and 11 articles were included. The following radiological parameters were observed: pelvic incidence (PI), pelvic tilt(PT), lumbar lordosis (LL), sagittal vertical axis(SVA), Cobb angle and T1-sacrum plumbline. Clinical outcome was assessed using the visual analogue scale(VAS) and Oswestry disability index (ODI)scores. The main complications were analysed, and the two groups were compared. Except for age, the two populations were homogeneous. Both techniques had the same number of posterior instrumented levels (7.4 ± 1.7). The AC group had a mean 3 ± 1.4 interbody fusions per patient. In the PSO group, all patients had 1 3CO and 89.8% of the osteotomies were performed at L2 or L3 vertebrae. No difference was observed between the two groups in terms of clinical outcomes. Both techniques were effective in sagittal parameters restoration with a final PI-LL mismatch = 4.4°. The PSO group had a statistically higher rate of intraoperative blood loss (p = 0.036), major complications, pseudoarthrosis and dural tears (p < 0.001). Both PSO and multiple AC are effective in treating ASD. Multiple AC seems more suitable when treating older patients because of a lower intraoperative blood loss, lower rate of major complications and fewer number of revision surgeries.

24. Lateral decubitus single position circumferential fusion (ALIF & PSF) improves perioperative outcomes compared to traditional anterior-posterior fusion

<h3>BACKGROUND CONTEXT</h3> Lateral decubitus single position anterior-posterior (AP) fusion utilizing anterior lumbar interbody fusion and percutaneous posterior fixation (SPS) is a novel, Minimally Invasive Surgical technique. Single position AP fusion with anterior or lateral interbodies has been shown to be a safe, effective technique to treat of lumbar degenerative disease. This study directly compares perioperative outcomes of SPS vs FLIP for degenerative pathologies. <h3>PURPOSE</h3> To determine if SPS with lateral ALIF (LALIF) improves perioperative outcomes compared to FLIP patients. <h3>STUDY DESIGN/SETTING</h3> Multicenter retrospective cohort study. <h3>PATIENT SAMPLE</h3> A total of 321 patients undergoing primary AP fusions with ALIF and bilateral percutaneous pedicle screw fixation at 5 institutions from 2015 to 2020. <h3>OUTCOME MEASURES</h3> Levels fused, inclusion of L4-L5, L5-S1, radiation dosage, operative time, estimated blood loss (EBL), length of stay (LOS), perioperative complications and radiographic outcomes. <h3>METHODS</h3> Retrospective analysis of primary ALIFs with bilateral percutaneous pedicle screw fixation between L4-S1 over 5 years at 5 institutions. Patients were grouped as FLIP or SPS. Outcome measures: levels fused, inclusion of L4-L5, L5-S1, radiation dosage, operative time, estimated blood loss (EBL), length of stay (LOS), perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), and PI-LL mismatch. Measures were compared using independent samples t-tests and chi-squared analyses, significance set at p<0.05. Cohorts were propensity matched (PSM) for levels fused. <h3>RESULTS</h3> A total of 321 patients: 124 SPS, 197 Flip were identified. PSM was performed due to differences between groups in levels fused, and proportion involving L4-5, yielding 248 patients: 124 SPS, 124 FLIP. The SPS cohort demonstrated significantly reduced OpTime (132.95±77.45 vs 261.79±91.65 min; p<0.001), EBL (120.44±217.08 vs 224.29±243.99 mL; p<0.001), LOS (2.07±1.26 vs 3.47±1.40 days; p<0.001), and rate of perioperative ileus (0.00% vs 6.45%; p=0.005). Radiation dose (39.79±31.66 vs 37.54±35.85 mGy; p=0.719) and perioperative complications including vascular injury (1.61% vs 1.61%; p=1.000), retrograde ejaculation (0.00% vs 0.81%, p=0.328), abdominal wall (0.81% vs 2.42%; p=0.338), neuropraxia (1.61% vs 0.81%; p=0.532), persistent motor deficit (0.00% vs 1.61%; p=0.166), wound complications (1.61% vs 1.61%; p=1.000), or VTE (0.81% vs 0.81%; p=0.972) were similar. No difference was seen in 90-day return to OR. Similar results were noted in subanalyses of single-level L4-L5 or L5-S1 fusions. On radiographic analysis the SPS cohort had greater changes in LL (4.22±11.14 vs 0.43±8.07 deg; p=0.005) and PI-LL mismatch (-4.78±8.77 vs -0.39±7.51 deg; p=0.002). <h3>CONCLUSIONS</h3> Single position lateral ALIF with percutaneous posterior fixation improves operative efficiency, EBL, LOS, rate of ileus and maintains safety compared to supine ALIF with prone percutaneous pedicle screws between L4-S1. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

142. A prospective multicenter evaluation of the relationship between standing and recumbent spinopelvic alignment in supine, lateral or prone position

<h3>BACKGROUND CONTEXT</h3> Spinopelvic alignment is important for successful spinal fusion outcomes and is traditionally measured on standing X-rays. There is little data on the change in alignment brought about by intraoperative recumbent positioning, and whether there are differences between supine, lateral and prone positions. <h3>PURPOSE</h3> To assess changes in spinopelvic alignment between preoperative standing X-rays and intraoperative recumbent imaging in supine, lateral and prone positions. Secondarily, to assess the effect of a Wilson frame on alignment among prone patients. <h3>STUDY DESIGN/SETTING</h3> Prospective observational multicenter. <h3>PATIENT SAMPLE</h3> Patients undergoing lumbar spinal fusion surgery. <h3>OUTCOME MEASURES</h3> Pelvic incidence - lumbar lordosis (PI-LL mismatch); ideal lumbar lordosis - lumbar lordosis (ILL-LL) mismatch in pre- and intraoperative imaging. <h3>Methods</h3> We performed a prospective multicenter study on lumbar spinal fusion patients. Sagittal parameters (lumbar lordosis [LL] and pelvic incidence [PI]) were measured on preoperative standing and intraoperative recumbent images (supine, lateral or prone). Images were deemed as aligned or malaligned, based on whether LL was within 10° of PI or of ideal LL (ILL), defined by the equation 0.5PI + 28. The prone group was sub-analyzed depending on whether a Wilson frame was used. <h3>Results</h3> A total of 403 patients (53% female) underwent spinal fusion in the following positions: supine (41), lateral (167) and prone (195). Standing to recumbent LL change (mean, median): supine (4.6, 3.0); lateral (-1.6, 0); prone (-1.2, -1.0). Standing to recumbent PI-LL mismatch change (mean, median): supine (-4.6, -4.0); lateral (1.9, 1.0); prone (-0.7, 0). Standing to recumbent ILL-LL mismatch change (mean, median): supine (-3.6, -2.0); lateral (1.7, 1.0); prone (0.2, 0.5). Using the PI-LL method, proportion of aligned patients (standing vs recumbent): supine (46.3% vs 63.4%, p=0.07); lateral (59.3% vs 59.3%, p=1.0); prone (57.9% vs 63.6%, p=0.17). Using the ILL-LL method, proportion of aligned patients (supine vs recumbent): supine (53.7% vs 65.9%, p=0.10); lateral (58.1% vs 61.1%, p=0.45); prone (59.0% vs 64.6%, p=0.15). In the prone position, Wilson frame significantly worsened PI-LL mismatch (6.8 vs -3.3, p<0.0001) and ILL-LL mismatch (9.4 vs -2.9, p<0.0001). <h3>Conclusions</h3> Mean change in LL brought about by recumbent positioning is small, whether in supine, lateral or prone position, and the proportion of aligned patients did not significantly change. In the prone position, use of a Wilson frame is associated with significantly worsened sagittal alignment. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.