Postoperative Sagittal Alignment Research Articles

Predicting surgical outcome and sagittal alignment change in patients with cervical spondylosis and degenerative kyphosis after anterior cervical discectomy and fusion

The aim of this study was to forecast the risk factors of poor outcomes and postoperative loss of lordosis or recurrence of kyphosis. In this retrospective study, 101 patients with cervical spondylosis and preoperative kyphosis who underwent anterior cervical discectomy and fusion (ACDF) were enrolled, between June 2015 and June 2019. Patients were grouped according to the recovery rate of Japanese Orthopaedic Association (JOA) score whether more than 50%, and the change of postoperative cervical Cobb angle. There were 22 cases with less than 50% of recovery rate and 35 cases with the worsening of postoperative sagittal alignment (WPSA). Multivariate linear-regression analysis was conducted with the data. Advanced age (p = 0.019), longer duration of symptoms (p = 0.003) and loss of local Cobb angle (LCA) after surgery (p = 0.031) was significantly associated with a poor clinical outcome. A whole kyphosis (p = 0.009), aggravated neck pain after surgery (p = 0.012), preoperative lower thoracic 1 (T1) (p < 0.001), bigger change of C2-7 sagittal vertical axis (SVA) (p = 0.008) and adjacent segment degeneration (ASD) (p = 0.024) was significantly associated with the WPSA. Preoperative health education, nutritional support and early postoperative rehabilitation intervention, in perioperative period, were recommended for patients with advance age, longer duration of symptoms, whole cervical kyphosis and lower T1. Postoperative sagittal malalignment was related to neck pain and ASD after surgery.

The Impact of Preoperative Sagittal Imbalance on Long-term Postoperative Outcomes Following Minimally Invasive Laminectomy.

Background: Postoperative sagittal alignment has been shown to be associated with patient-reported outcome measures (PROMs) following open lumbar decompression procedures, although it is unknown whether preoperative sagittal imbalance affects clinical outcomes of minimally invasive surgical (MIS) decompression only surgery. Purpose: We sought to evaluate the impact of preoperative pelvic incidence-lumbar lordosis (PI-LL) imbalance on PROMs after MIS laminectomy for the treatment of neurogenic claudication symptoms. Methods: We conducted a retrospective cohort study of adult patients undergoing MIS laminectomy for degenerative lumbar spinal stenosis between April 2017 and April 2021 at a single institution. Of the 52 patients included (mean follow-up, 17 months) radiographs were taken prior to surgery and assessed for sagittal alignment parameters. Patients were grouped based on the preoperative PI-LL (balanced vs unbalanced). Changes in PROMs were compared between unbalanced PI-LL and balanced PI-LL groups. Minimal clinically important difference (MCID) for Oswestry Disability Index (ODI) was also assessed. Results: Of the 52 patients, 17 (32.7%) had unbalanced age-adjusted preoperative PI-LL. There was no significant difference found in PROMs between unbalanced and balanced PI-LL groups preoperatively or at final follow-up. Compared with those with unbalanced PI-LL, patients with balanced PI-LL were shown to have no added benefit in achieving MCID for ODI at long-term follow-up and no added benefit in the time to achieving MCID. Conclusion: These retrospective findings suggest that patients with unbalanced preoperative PI-LL may experience significant benefit in long-term clinical outcomes following MIS laminectomy, similarly to those with balanced PI-LL at baseline. The findings also suggest that the presence of sagittal imbalance preoperatively may not appreciably influence the long-term clinical outcomes following MIS laminectomy. Prospective study involving a larger population is warranted.

Validation of a preoperative formula to estimate postoperative pelvic sagittal alignment and mobility before performing total hip arthroplasty for patients with hip osteoarthritis

BackgroundAlthough it is important to consider pelvic alignment and mobility in the standing and sitting positions before THA, it is not known how to preoperatively predict individual postoperative pelvic alignment and mobility. The purpose of this study was to investigate the pelvic alignment and mobility before and after THA, and to develop a predictive formula using preoperative factors to calculate postoperative sagittal alignment and mobility.MethodsOne hundred seventy patients were assessed. The 170 patients were randomly divided into a prediction model analysis group (n = 85) and an external validation group (n = 85). In the prediction model analysis group, preoperative spinopelvic parameters were used to develop the predictive formulas to predict the postoperative sacral slope (SS) in standing and sitting positions and ΔSS. These were applied to the external validation group and assessed.ResultsR2 in multiple linear regression models for postoperative SS in standing, SS in sitting and ΔSS were 0.810, 0.672, and 0.423, respectively. The values of predicted and postoperative parameters were very close with no significant difference: SS in standing (33.87 vs. 34.23, P = 0.834), SS in sitting (18.86 vs. 19.51, P = 0.228), and ΔSS (15.38 vs. 14.72, P = 0.619).ConclusionThe present study showed that the pelvic alignment and mobility after THA can be predicted using preoperative factors. Although a model with higher accuracy is needed, it is important to use a predictive formula to estimate the postoperative condition before performing THA.

Revision surgery following long lumbopelvic constructs for adult spinal deformity: prospective experience from two dedicated databases.

Pan Lumbar Arthodesis (PLA) are often required for Adult Spinal Deformity (ASD) correction, reducing significantly the compensatory capacity in case of postoperative sagittal malalignment. Few papers have investigated outcomes and complications in this vulnerable subset of patients. The objective of this study was to assess revision surgery rate for PLA in ASD, its risk factors and impact on clinical outcomes. Retrospective multicenter review of prospective ASD data from 7 hospitals covering Europe and Asia. ASD patients included in two prospective databases having a posterior instrumentation spanning the whole lumbar region with more than 2-years of follow-up were reviewed. Demographic, surgical, radiographic parameters and Health-Related Quality of Life (HRQoL) scores were analyzed. Univariate and multivariate regression models analyzed risk factors for revision surgery as well as surgical outcomes. Patients with Early versus Late and PJK versus Non-PJK mechanical complications were also compared. Out of 1359 ASD patients included in the database 589 (43%) had a PLA and 357 reached 2-years mark. They were analyzed and compared to non-PLA patients. Average age was 67 and 82% were females. 100 Patients (28.1%) needed 114 revision surgeries (75.4% for mechanical failures). Revised patients were more likely to have a nerve system disorder, higher BMI and worst immediate postoperative alignment (as measured by GAP Parameters). These risk factors were also associated with earlier mechanical complications and PJK. Deformity and HRQoL parameters were comparable at baseline. Non-revised patients had significantly better clinical outcomes at 2-years (SRS 22 scores, ODI, Back pain). Multivariate analysis could identify nerve system disorder (OR 4.8; CI 1.8-12.6; p = 0.001), postoperative sagittal alignment (GAP Score) and high BMI (OR 1.07; CI 1.01-1.13; p = 0.004) as independent risk factors for revisions. Revision surgery due to mechanical failures is relatively common after PLA leading to worse clinical outcomes. Prevention strategies should focus on individualized restoration of sagittal alignment and better weight control to decrease stress on these rigid constructs in non-compliant spines. Nerve system disorders independently increase revision risk in PLA. Prognosis.

Do On-Table Radiographs Predict Postoperative Sagittal Alignment after Posterior Lumbar Fusion?

To determine if intraoperative on-table lumbar lordosis and segmental lordosis correlate with postoperative lordosis following single-level posterolateral decompression and fusion (PLDF) or transforaminal lumbar interbody fusion (TLIF). Electronic medical records were reviewed for patients ≥18 years old who underwent PLDF or TLIF between 2012 and 2020. Lumbar lordosis and segmental lordosis were compared between pre-, intra-, and postoperative radiographs using paired t tests. Significance was set at P < 0.05. A total of 200 patients met inclusion criteria. No significant differences in preoperative, intraoperative, or postoperative measurements were found between groups. Patients who underwent PLDF experienced less disc height loss over 1 year postoperatively (PLDF: 0.45 ± 0.9 mm vs. TLIF: 1.2 ± 1.4 mm, P < 0.001). Lumbar lordosis significantly decreased between intraoperative to postoperative radiographs at 2-6 weeks for PLDF (Δ: -4.0°, P<0.001) and TLIF (Δ: -5.6°, P < 0.001), but no change was identified between the intraoperative and >6 month postoperative radiographs for PLDF (Δ: -0.3°, P= 0.634) or TLIF (Δ: -1.6°, P= 0.087). Segmental lordosis significantly increased from the preoperative to post-instrumentation intraoperative radiographs for PLDF (Δ: 2.7°, P < 0.001) and TLIF (Δ: 1.8°, P < 0.001), but it subsequently decreased at the final follow up for PLDF (Δ: -1.9°, P < 0.001) and TLIF (Δ: -2.3°, P < 0.001). Subtle decreases in lumbar lordosis may be noticed in early postoperative radiographs compared with intraoperative images on Jackson operative tables. However, these changes are not present at 1-year follow-up as lumbar lordosis increases to a similar level as intraoperative fixation.

Crossing the cervicothoracic junction: an evaluation of radiographic alignment, functional outcomes, and patient-reported outcomes.

There is currently no consensus regarding the appropriate lower instrumented vertebra (LIV) for multilevel posterior cervical fusion (PCF) constructs between C7 and crossing the cervicothoracic junction (CTJ). The goal of the present study was to compare postoperative sagittal alignment and functional outcomes among adult patients presenting with cervical myelopathy undergoing multilevel PCF terminating at C7 versus spanning the CTJ. A single-institution retrospective analysis (January 2017-December 2018) was performed of patients undergoing multilevel PCF for cervical myelopathy that involved the C6-7 vertebrae. Pre- and postoperative cervical spine radiographs were analyzed for cervical lordosis, cervical sagittal vertical axis (cSVA), and first thoracic (T1) vertebral slope (T1S) in two randomized independent trials. Modified Japanese Orthopaedic Association (mJOA) and Patient-Reported Outcomes Measurement Information System (PROMIS) scores were used to compare functional and patient-reported outcomes at the 12-month postoperative follow-up. Sixty-six consecutive patients undergoing PCF and 53 age-matched controls were included in the study. There were 36 patients in the C7 LIV cohort and 30 patients in the LIV spanning the CTJ cohort. Despite significant correction, patients undergoing fusion remained less lordotic than asymptomatic controls, with a C2-7 Cobb angle of 17.7° versus 25.5° (p < 0.001) and a T1S of 25.6° versus 36.3° (p < 0.001). The CTJ cohort had superior alignment corrections in all radiographic parameters at the 12-month postoperative follow-up compared with the C7 cohort: increase in T1S (ΔT1S 14.1° vs 2.0°, p < 0.001), increase in C2-7 lordosis (ΔC2-7 lordosis 11.7° vs 1.5°, p < 0.001), and decrease in cSVA (ΔcSVA 8.9 vs 5.0 mm, p < 0.001). There were no differences in the mJOA motor and sensory scores between cohorts pre- and postoperatively. The C7 cohort reported significantly better PROMIS scores at 6 months (22.0 ± 3.2 vs 11.5 ± 0.5, p = 0.04) and 12 months (27.0 ± 5.2 vs 13.5 ± 0.9, p = 0.01) postoperatively. Crossing the CTJ may provide a greater cervical sagittal alignment correction in multilevel PCF surgeries. However, the improved alignment may not be associated with improved functional outcomes as measured by the mJOA scale. A new finding is that crossing the CTJ may be associated with worse patient-reported outcomes at 6 and 12 months of postoperative follow-up as measured by the PROMIS, which should be considered in surgical decision-making. Future prospective studies evaluating long-term radiographic, patient-reported, and functional outcomes are warranted.

Association between sagittal alignment and loads at the adjacent segment in the fused spine: a combined clinical and musculoskeletal modeling study of 205 patients with adult spinal deformity

PurposeSagittal malalignment is a risk factor for mechanical complications after surgery for adult spinal deformity (ASD). Spinal loads, modulated by sagittal alignment, may explain this relationship. The aims of this study were to investigate the relationships between: (1) postoperative changes in loads at the proximal segment and realignment, and (2) absolute postoperative loads and postoperative alignment measures.MethodsA previously validated musculoskeletal model of the whole spine was applied to study a clinical sample of 205 patients with ASD. Based on clinical and radiographic data, pre-and postoperative patient-specific alignments were simulated to predict loads at the proximal segment adjacent to the spinal fusion.ResultsWeak-to-moderate associations were found between pre-to-postop changes in lumbar lordosis, LL (r = − 0.23, r = − 0.43; p < 0.001), global tilt, GT (r = 0.26, r = 0.38; p < 0.001) and the Global Alignment and Proportion score, GAP (r = 0.26, r = 0.37; p < 0.001), and changes in compressive and shear forces at the proximal segment. GAP score parameters, thoracic kyphosis measurements and the slope of upper instrumented vertebra were associated with changes in shear. In patients with T10-pelvis fusion, moderate-to-strong associations were found between postoperative sagittal alignment measures and compressive and shear loads, with GT showing the strongest correlations (r = 0.75, r = 0.73, p < 0.001).ConclusionsSpinal loads were estimated for patient-specific full spinal alignment profiles in a large cohort of patients with ASD pre-and postoperatively. Loads on the proximal segments were greater in association with sagittal malalignment and malorientation of proximal vertebra. Future work should explore whether they provide a causative mechanism explaining the associated risk of proximal junction complications.

Periprosthetic distal femur fractures treated by retrograde intramedullary nails with a 10-degree distal bend achieve significantly better post-operative radiographic alignment when compared to conventional retrograde nails

IntroductionPeriprosthetic distal femur fractures (PPDFFs) are a common complication after total knee arthroplasty (TKA). In the setting of well-fixed TKA components, treatment options include retrograde intramedullary nailing (rIMN) or lateral locked plating. Treatment with rIMN has historically been associated with potential for extension deformity when using conventional nails. We hypothesized that the PPDFFs treated with an intramedullary nail with a specifically designed 10-degree distal bend for periprosthetic fractures would result in improved post-operative sagittal alignment compared to conventional intramedullary nails. Materials and methodsThe study was conducted at a level-1 trauma center over a 12-year period (2010 - 2022). Patients over the age of 18 who sustained a PPDFF treated with rIMN were identified. The primary outcomes of the study were post-operative coronal and sagittal alignment determined by reviewing post-operative radiographs. ResultsA total of 50 patients were included. Twenty-three patients were treated with a rIMN with a 10° distal bend. Twenty-seven patients were treated with a rIMN with distal bend of 5° The mean aPDFA for the 10° distal bend group was 81.7° compared to 92.8° in the 5° distal bend group (p<0.001). There were 3/23 (13%) significant sagittal plane deformities the 10° distal bend group compared to 11/27 (41%) in the 5° distal bend group (p = 0.03). There was one patient with a post-operative extension deformity in the 10° distal bend group compared to 11 patients in the 5° distal bend group (p = 0.02). ConclusionRetrograde intramedullary nailing of PPDFF with a 10° distal bend results in significantly better alignment in the sagittal plane when compared to a conventional 5° nail. The use of a 5° nail resulted in an extension deformity significantly more frequently. We therefore recommend the utilization of a rIMN with a 10° distal bend when treating PPDFFs. SummaryPeriprosthetic distal femur fractures are a common complication following total knee arthroplasty. While several studies report on the use of retrograde intramedullary nails in the treatment of periprosthetic distal femur fractures, there are limited reports of the use of a novel retrograde intramedullary nail with a 10° distal bend in the treatment of these injuries. Herein we present a radiographic study comparing coronal and sagittal postoperative alignment following treatment with retrograde intramedullary nails with a 10° distal bend versus conventional retrograde nails with a 5° distal bend.

Restoration of thoracic kyphosis in adolescent idiopathic scoliosis with patient-specific rods: did the preoperative plan match postoperative sagittal alignment?

To determine if the planned sagittal profile for thoracic kyphosis (TK) restoration was achieved after adolescent idiopathic scoliosis (AIS) surgery using a novel hybrid construct with apical double bands and precontoured patient-specific rods (PSR) made according to the detailed surgical plan for the desired sagittal plane. AIS patients with a Lenke type 1-4 primary right thoracic curve who underwent corrective surgery by a single surgeon and had minimum 24-month follow-up were analyzed retrospectively from a prospective database. All patients underwent simultaneous translation on two rods with apical double bands and PSR. Clinical outcomes in terms of sagittal 2D TK (T4-T12), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), PI-LL mismatch, rod angle, and rod deflection were compared between preoperative, planned, and 24-month data, while 3D apical rotation, 3D TK (T5-T12), sagittal thoracolumbar angle, degree of curvature at L1-L4 and L4-S1, proximal junctional angle, and distal junctional angle were compared at baseline and at 6 and 24months postoperatively. SRS-22 questionnaire scores were obtained at baseline and 24months postoperatively. Forty-eight patients were included. Study patients had a median coronal thoracic curve of 62.7° preoperatively and 22.4° at 24-month follow-up (p < 0.001). Median TK gain was 6.5° for the entire cohort (n = 48) and 19.1° in the Lenke type 1 and 2 hypokyphotic subgroup (n = 14). Both groups had no significant changes between planned and 24-month TK (p = 0.068 and p = 0.943, respectively), rod angle (p = 0.776 and p = 0.548, respectively), or rod deflection (p = 0.661 and p = 0.850, respectively). For the overall study cohort, median LL gain was 7.0° (p < 0.001), 3D apical derotation was 10.7° (p < 0.001), and change in 3D TK was 36° (p < 0.001). No instance of proximal junctional kyphosis was observed. SRS-22 scores for pain, self-image, and satisfaction differed significantly between the preoperative and 24-month follow-up time-points. With sagittal plane planning, desired TK, improved reciprocal changes in LL, and minimal changes in rod shape can be achieved in patients with AIS.

Long-term opioid medication profile of European adult spinal deformity patients: minimum five years follow-up study

BACKGROUND CONTEXTThere remains significant variability in the use of postoperative opioids. On one end, it is proven that appropriate pain control is a critical aspect of patient management; on the other end, past few decades have been associated with major increases in opioid-related overdoses and addiction treatment. We hypothesized that several pre- and postoperative risk factors affecting long-term opioid use could be identified. PURPOSEEvaluation of factors associated with minimum 5-year postoperative opioid use following adult spinal deformity surgery. STUDY DESIGN/SETTINGProspectively followed study group database. PATIENT SAMPLEAdult spinal deformity patients who underwent elective spine surgery between 2009 and 2016 were included. OUTCOME MEASURESOpioid usage or otherwise at minimum 5 years follow-up. Use of nonopioid analgesics, weak and strong opioids METHODSRetrospective analysis of patients undergoing elective spinal deformity surgery. A total of 37 factors comprising patient characteristics, radiographic measurements, operative details, preoperative and early postoperative opioid use, and mechanical complications and revisions were analyzed. Details on identified factors were provided. RESULTSA total of 265 patients (215F, 50M) from five sites were included. The mean follow-up duration was 68.4±11.7 (60–102) months. On average, 10.6±3.5 levels were fused. Preoperatively, 64 (24.2%) patients were using opioids. The rate of opioid users increased to 33.6% at 6 weeks and decreased to 21.5% at 6 months. During follow-up, there were patients who discontinued opioids, while others have started and/or restarted using opioids. As a result, 59 (22.3%) patients were still on opioids at the latest follow-up. Multivariate analyses showed that factors independently affecting opioid use at an average of 68 months postoperatively, in order of significance, were opioid use at sixth weeks, preoperative opioid use and opioid use at sixth months with the odds ratios of 2.88, 2.51, and 2.38 respectively. At these time points, factors such as age, number of comorbidities, tobacco use, the time of the last prior spine surgery and postoperative sagittal plane alignment affected opioid usage rates. CONCLUSIONSOpioid usage at 6 weeks was found to be more predictive of long-term opioid use compared to preoperative use. Patients should be well informed to have realistic expectations regarding opioid use when considering adult spinal deformity surgery.

Realistic long-term dysphagia rates after anterior cervical discectomy with fusion: is there a correlation with postoperative sagittal alignment and lordosis at a minimum 2-year follow-up?

Postoperative dysphagia after anterior cervical discectomy and fusion (ACDF) has many contributing factors, and long-term data are sparse. The authors evaluated dysphagia after ACDF based on levels fused and cervical sagittal parameters. Patients who underwent ACDF between 2009 and 2018 at the University of California, San Francisco (UCSF), were retrospectively studied. Dysphagia was evaluated preoperatively, immediately postoperatively, and at last follow-up using the UCSF dysphagia score. Dysphagia was categorized as normal (level 7), mild (levels 5 and 6), moderate (levels 3 and 4), and severe (levels 1 and 2). The UCSF mild dysphagia score was further classified as "minimal dysphagia," while moderate and severe dysphagia were classified as "significant dysphagia." "Any dysphagia" included any dysphagia, regardless of grade. Cervical sagittal parameters were measured preoperatively, immediately postoperatively, and at last follow-up. A total of 131 patients met inclusion criteria. The mean follow-up was 43.89 (24-142) months. Seventy-eight patients (59.5%) reported dysphagia immediately postoperatively, and 44 patients (33.6%) reported some dysphagia at last follow-up (p < 0.001). The rates of moderate dysphagia were 13.0% immediately postoperatively and 1.5% at the last follow-up (p < 0.001). Twenty-two patients (16.8%) had significant dysphagia immediately postoperatively, and 2 patients (1.5%) had significant dysphagia at last follow-up (p < 0.001). Patients with immediate postoperative dysphagia had less C2-7 preoperative lordosis (-9.35°) compared with patients without (-14.15°, p = 0.029), but there was no association between C2-7 lordosis and dysphagia at last follow-up (p = 0.232). The prevalence rates of immediate postoperative dysphagia and long-term dysphagia were 87.5% and 58.3% in ≥ 3-level ACDF; 64.0% and 40.0% in 2-level ACDF; and 43.9% and 17.5% in 1-level ACDF, respectively (p < 0.001). The realistic incidence of any dysphagia after ACDF was 59.5% immediately postoperatively and 33.6% at the minimum 2-year follow-up, higher than previously published rates. However, most dysphagia was not severe. The number of fused levels was the most important risk factor for long-term dysphagia, but not for immediate postoperative dysphagia. Loss of preoperative C2-7 lordosis was associated with immediate postoperative dysphagia, but not long-term dysphagia. ACDF segmental lordosis and cervical sagittal vertical axis were not associated with long-term dysphagia in ACDF.

Long spine fusions to the sacrum-pelvis are associated with greater post-operative proximal junctional kyphosis angle in sitting position.

A single-centre retrospective study. Although adult patients spend most of their time in sitting positions, the assessment of spinopelvic parameters in adult deformity surgery is commonly performed in standing X-rays. Our study compares the standing and sitting sagittal alignment parameters in subjects who underwent thoracolumbar fusion. Patients who underwent corrective surgery for adult scoliosis with at least five instrumented vertebra were stratified according to the upper instrumented vertebra (UIV) and pelvic fixation. Group A:UIV proximal to T6 with pelvis fixation. B:UIV lower than T6 and pelvic fixation. Group C: thoracolumbar fusion without pelvic fixation. Post-operative spinopelvic sagittal parameters were measured in both standing and sitting X-rays. A total of 51 patients were enrolled in the study (11:Males and 40:Females). The mean age was 52.3 ± 21.7y/o. The comparison of post-operative standing and sitting X-ray within the group A and B showed that a significant change was observed in terms of JA-Junctional Angle-(Group A 6.3 ± 4.3 vs. 8.1 ± 3.3, p value = 0.03) (Group B 8.5 ± 6.4 vs. 10.9 ± 6.4, p value = 0.02). Group C showed statistically significant difference in terms of PT (15.6 ± 11.2 vs. 19.3 ± 9.2, p value = 0.04), AVA-Acetabular Version Angle-(41.1 ± 5.9 vs. 48.3 ± 6.6, p value < 0.01) and LL (- 51.3 ± 16.0 vs. - 42.6 ± 10.7, p value < 0.01). In our series, the post-operative sagittal alignment showed peculiar behaviours and adaptations in sitting position, depending on the length and the site of the instrumented area. If the pelvis is included, the JA tends to significantly increase in sitting position. These findings can improve the knowledge of pathologies as proximal junctional kyphosis or specific cases of anterior hip impingement. IV.

Preoperative excessive lateral anterior tibial subluxation is related to posterior tibial tunnel insertion with worse sagittal alignment after anterior cruciate ligament reconstructions.

ObjectiveTo investigate whether preoperative lateral anterior tibial subluxation (LATS) measured from magnetic resonance imaging (MRI) can influence tibial insertion and postoperative sagittal alignment after anterior cruciate ligament reconstructions (ACLRs).Methods84 patients who underwent single-bundle ACLRs were retrospectively investigated. Among them, 39 patients (LATS of <6 mm) 23 patients (LATS of ≥6 mm and <10 mm) and 22 patients (excessive LATS of ≥10 mm) were defined as group 1, 2 and 3, respectively. LATS, the position of graft insertion into tibia as ratio of anterior-posterior width (AP ratio) and the sagittal graft angle (SGA) were postoperatively assessed from MRI at 2-year follow-up. Following linear regression analyses were employed.ResultsThe group 3 exhibited the largest preoperative LATS and remained the most postoperative LATS. Moreover, the group 3 possessed the most posteriorly located tunnel insertion with the largest AP ratio and the most vertical graft orientation. Of all included patients, a moderate correlation was demonstrated between pre- and postoperative LATS (r = 0.635). A low correlation was observed between preoperative LATS and AP ratio (r = 0.300) and a moderate correlation was displayed between AP ratio and SGA (r = 0.656).ConclusionFor ACL injuries with excessive LATS (≥10 mm), most posteriorly located tibial insertion was found out, and worse sagittal alignment containing high residual LATS was associated with more vertical graft orientation following ACLRs.

225. Comparison of single position prone lateral lumbar interbody fusion and lateral lumbar interbody fusion with repositioning in revision lumbar spinal fusion

<h3>BACKGROUND CONTEXT</h3> Prone LLIF (P-LLIF) is a novel technique allowing for placement of a lateral interbody in the prone position and allowing posterior decompression and revision of posterior instrumentation without repositioning. To date, studies evaluating the P-LLIF have been small single surgeon series. This multicentre retrospective cohort examines perioperative outcomes and complications of single position P-LLIF againsttraditional Lateral LLIF (L-LLIF) technique with patient repositioning in patients undergoing revision lumbar fusion surgery. <h3>PURPOSE</h3> To evaluate the feasibility and safety of the single-position P-LLIF technique for revision lumbar fusion surgery. <h3>STUDY DESIGN/SETTING</h3> Multicenter retrospective cohort study. <h3>PATIENT SAMPLE</h3> A total of 101 patients undergoing revision circumferential fusion with lateral lumbar interbody fusion (LLIF) were included, of which 43 had P-LLIF and 58 had L-LLIF. <h3>OUTCOME MEASURES</h3> Outcome measures included levels fused, operative time, estimated blood loss and perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), PI-LL mismatch and segmental lumbar lordosis. <h3>METHODS</h3> A multicenter retrospective cohort study was performed from 4 institutions from the USA and Australia of patients undergoing revision anterior-posterior lumbar fusion via either: 1) single-position prone LLIF (P-LLIF); or 2) lateral decubitus LLIF with repositioning to prone (L-LLIF) between January 2015 and November 2021. Patients with greater than 4 levels fused were excluded. Demographics, perioperative outcomes, complications and radiological outcomes were compared using independent samples t-tests and chi-squared analyses as appropriate with significance set at p<0.05. <h3>RESULTS</h3> A total of 101 patients undergoing revision lateral lumbar interbody fusion surgery were included, of which 43 had P-LLIF and 58 had L-LLIF. Age, BMI and CCI were similar between groups. The number of posterior levels fused (2.21 P-LLIF vs 2.66 L-LLIF, p=0.469) and interbody levels fused (1.23 P-LLIF vs 1.25 L-LLIF, p=0.838) were similar between groups. Levels decompressed, posterior column osteotomy and anterior column release were similar between groups. Operative time was significantly less in the P-LLIF group compared to the L-LLIF group (151 vs 206 min, p=0.004). EBL was similar between groups (150 mL P-LLIF vs 182 mL L-LLIF, p=0.31) and there was a trend toward reduced length of stay (2.7 vs 3.3 days, p=0.09). No significant difference was demonstrated in perioperative or postoperative complications between P-LLIF and L-LLIF groups. Radiographic analysis demonstrated no significant differences in preoperative or postoperative sagittal alignment as measured by lumbar lordosis, PI-LL mismatch, or segmental lumbar lordosis between groups. <h3>CONCLUSIONS</h3> P-LLIF significantly improves operative efficiency and may reduce length of stay when compared to L-LLIF and repositioning for revision lumbar fusion. No increase in complications was demonstrated by P-LLIF or trade-offs in sagittal alignment restoration. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P106. Lower Hounsfield units and severe multifidus sarcopenia are independent predictors of increased risk for proximal junctional kyphosis and failure following thoracolumbar fusion

<h3>PURPOSE</h3> The purpose of the present study was to determine demographic and radiographic variables that predict an increased risk of proximal junctional kyphosis (PJK) or proximal junctional failure (PJF) following thoracolumbar fusion. <h3>METHODS</h3> We retrospectively reviewed a cohort of patients greater than 50 years of age who underwent posterior instrumented fusion with pelvic fixation and a construct that terminated proximally between T10 to L2 between the years 2013-2020. Patient demographic information was collected and the Modified Frailty Index (mFI) and Charlson Comorbidity Index (CCI) scores were calculated for each patient. Patients were subdivided into three groups: (1) no PJK or PJF, (2) PJK without PJF, and (3) PJF. These subgroups were then compared based upon demographics, preoperative and 1-year postoperative sagittal alignment parameters, bone mineral density (BMD) and paraspinal sarcopenia. We utilized student's T-test and ANOVA to compare means within and between groups, respectively. Multivariable analyses were performed to determine risk factors for PJK and PJF. P values <0.05 were considered significant. <h3>RESULTS</h3> We identified 150 patients for inclusion in this study with a mean age of 67.0 years and an average follow-up of 32 months. The subgroup of patients with no PJK/PJF demonstrated a significantly higher HU at the UIV (148.3±34.5) than patients who developed PJK (117.8 ±41.9) or PJF (118.8 ±41.8; P < 0.001). There was a much higher rate of severe multifidus fatty infiltration observed in patients who developed PJF (78.9%) or PJK (76.0%) than in patients who did not develop PJK/PJF (34.0%; P < 0.001). Furthermore, no patient that developed PJK or PJF had normal multifidus quality. Multivariate analysis identified both mean UIV HU (0.80, 95% CI 0.69-0.93; P < 0.001) and moderate-severe multifidus sarcopenia (5.40, 95% CI 1.8-16.1; P < 0.001) as independent predictors of increased risk of PJK and PJF. <h3>CONCLUSIONS</h3> Patients with lower mean HU at the UIV and a higher degree of multifidus fatty infiltration are at increased risk of PJK and PJF following thoracolumbar fusions that terminate proximally between T10 and L2. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Fatty infiltration in cervical extensor muscle: is there a relationship with cervical sagittal alignment after anterior cervical discectomy and fusion?

PurposeTo investigate the relationship between the preoperative paraspinal Goutalier grade of fatty infiltration and postoperative cervical sagittal alignment in patients undergoing anterior cervical discectomy and fusion (ACDF).MethodsA total of 101 patients who underwent single-level ACDF with the Zero-profile implant system between March 2011 and April 2020 were included in this study. Cervical sagittal alignment parameters, including the C2-C7 Cobb angle, functional spinal unit (FSU) angle, cervical sagittal vertical axis (SVA), and T1 slope (T1S), were assessed. Preoperative magnetic resonance images were used to classify patients according to Goutalier grade. Clinical outcomes including Neck Disability Index (NDI) scores, Japanese Orthepaedic Association (JOA) scores and Visual Analogue Scale (VAS) scores were collected and analyzed.ResultsAccording to the Goutalier grade, 33 patients were classified as Goutalier 0–1 (Group A), 44 were classified as Goutalier 1.5–2 (Group B), and 24 were classified as Goutalier 2.5–4.0 (Group C). The mean age among the three groups showed significant differences (P = 0.007). At the last follow-up, the C2-C7 Cobb angle, FSU angle, and T1S improved after the surgery among the groups. Although there were varying degrees of loss of curvature among the different groups during the follow-up period, the postoperative cervical sagittal alignment parameters demonstrated no statistical differences among the three groups (P > 0.05). In addition, patients in all groups experienced significant relief of their symptoms, and the clinical scores were comparable among the groups (P > 0.05).ConclusionThe complex nature of anterior cervical surgery requires surgical attention both in decompression and sagittal alignment. Our study demonstrates satisfactory postoperative cervical sagittal alignment of patients despite different grades of fatty infiltration of the multifidus muscle following single-level ACDF. Based on our results, the improvement and maintenance of cervical sagittal alignment after ACDF remains a complex problem that spine surgeons should consider before surgery.

Postoperative Sagittal Balance Has Only a Limited Role in the Development of Adjacent Segment Disease After Lumbar Spine Fusion for Degenerative Lumbar Spine Disorders: A Subanalysis of the 10-year Follow-up Study.

Study Design.Retrospective additional analysis of a prospective follow-up study.Objectives.We aimed to find out whether poor postoperative sagittal alignment increases revisions for adjacent segment disease (ASD) after lumbar spine fusion (LSF) performed for degenerative lumbar spine disease.Summary of Background Data.Revisions for ASD accumulate over time after LSF for degenerative lumbar spine disease. The etiology of ASD is considered multifactorial. Yet, the role of postoperative sagittal balance in this process remains controversial.Materials and Methods.A total of 215 consecutive patients who had undergone an elective LSF surgery for spinal stenosis with (80%) or without (20%) spondylolisthesis were analyzed. Spinal reoperations were collected from the hospital records. Preoperative and postoperative sagittal alignment were evaluated from standing radiographs. The risk of revisions for ASD was evaluated by Cox proportional hazards regression models.Results.We did not find the poor postoperative balance [pelvic incidence−lumbar lordosis (LL) >9°] to significantly increase the risk of revisions for ASD: crude hazard ratio (HR)=1.5 [95% confidence interval (CI): 0.8–2.7], adjusted (by age, sex, pelvic incidence, fusion length, and the level of the caudal end of fusion): HR=1.7 (95% CI: 0.9–3.3). We found higher LL outside the fusion segment (LL−segmental lordosis) to decrease the risk of revisions for ASD: HR=0.9 (95% CI: 0.9–1.0).Conclusion.Poor sagittal balance has only a limited role as a risk factor for the revisions for ASD among patients with degenerative spinal disease. However, the risk for ASD might be the greatest among patients with reduced spinal mobility.

Does Interbody Cage Lordosis and Position Affect Radiographic Outcomes After Single-level Transforaminal Lumbar Interbody Fusion?

This was a retrospective cohort study. The objective of this study was to determine if the degree of interbody cage lordosis and cage positioning are associated with changes in postoperative sagittal alignment after single-level transforaminal lumbar interbody fusion (TLIF). Ideal sagittal alignment and lumbopelvic alignment have been shown to correlate with postoperative clinical outcomes. TLIF is one technique that may improve these parameters, but whether the amount of cage lordosis improves either segmental or lumbar lordosis (LL) is unknown. A retrospective review was performed on patients who underwent single-level TLIF with either a 5-degree or a 12-degree lordotic cage. LL, segmental lordosis (SL), disk height, center point ratio, cage position, and cage subsidence were evaluated. Correlation between center point ratio and change in lordosis was assessed using the Spearman correlation coefficient. Secondary analysis included multiple linear regression to determine independent predictors of change in SL. A total of 126 patients were included in the final analysis, with 51 patients receiving a 5-degree cage and 75 patients receiving a 12-degree cage. There were no differences in the postoperative minus preoperative LL (∆LL) (12-degree cage: -1.66 degrees vs. 5-degree cage: -2.88 degrees, P =0.528) or ∆SL (12-degree cage: -0.79 degrees vs. 5-degree cage: -1.68 degrees, P =0.513) at 1-month follow-up. Furthermore, no differences were found in ∆LL (12-degree cage: 2.40 degrees vs. 5-degree cage: 1.00 degrees, P =0.497) or ∆SL (12-degree cage: 1.24 degrees vs. 5-degree cage: 0.35 degrees, P =0.541) at final follow-up. Regression analysis failed to show demographic factors, cage positioning, or cage lordosis to be independent predictors of change in SL. No difference in subsidence was found between groups (12-degree cage: 25.5% vs. 5-degree cage: 32%, P =0.431). Lordotic cage angle and cage positioning were not associated with perioperative changes in LL, SL, or cage subsidence after single-level TLIF. Level III.

Clinical Validation of a Novel Musculoskeletal Modeling Framework to Predict Postoperative Sagittal Alignment.

A retrospective radiographic and biomechanical analysis of 108 thoracolumbar fusion patients from two clinical centers. This study aimed to determine the validity of a computational framework for predicting postoperative patient posture based on preoperative imaging and surgical data in a large clinical sample. Short-term and long-term studies on thoracolumbar fusion patients have discussed that a preoperative predictive model would benefit surgical planning and improve patient outcomes. Clinical studies have shown that postoperative alignment changes at the pelvis and intact spine levels may negatively affect postural balance and quality of life. However, it remains challenging to predict such changes preoperatively because of confounding surgical and patient factors. Patient-specific musculoskeletal models incorporated weight, height, body mass index, age, pathology-associated muscle strength, preoperative sagittal alignment, and surgical treatment details. The sagittal alignment parameters predicted by the simulations were compared with those observed radiographically at a minimum of three months after surgery. Pearson correlation coefficients ranged from r=0.86 to 0.95, and mean errors ranged from 4.1° to 5.6°. The predictive accuracies for postoperative spinopelvic malalignment (pelvic incidence minus lumbar lordosis>10°) and sagittal imbalance parameters (TPA>14°, T9PA>7.4°, or LPA>7.2°) were between 81% and 94%. Patients treated with long fusion (greater than five segments) had relatively lower prediction errors for lumbar lordosis and spinopelvic mismatch than those in the local and short groups. The overall model performance with long constructs was superior to those of the local (one to two segments) and short (three to four segments) fusion cases. The clinical framework is a promising tool in development to enhance clinical judgment and to help design treatment strategies for predictable surgical outcomes. 3.

The impact of preoperative supine radiographs on surgical strategy in adult spinal deformity.

Preoperative planning for adult spinal deformity (ASD) surgery is essential to prepare the surgical team and consistently obtain postoperative alignment goals. Positional imaging may allow the surgeon to evaluate spinal flexibility and anticipate the need for more invasive techniques. The purpose of this study was to determine whether spine flexibility, defined by the change in alignment between supine and standing imaging, is associated with the need for an osteotomy in ASD surgery. A single-center, dual-surgeon retrospective analysis was performed of adult patients with ASD who underwent correction of a thoracolumbar deformity between 2014 and 2018 (pelvis to upper instrumented vertebra between L1 and T9). Patients were stratified into osteotomy (Ost) and no-osteotomy (NOst) cohorts according to whether an osteotomy was performed (Schwab grade 2 or higher). Demographic, surgical, and radiographic parameters were compared. The sagittal correction from intraoperative prone positioning alone (sagittal flexibility percentage [Sflex%]) was assessed by comparing the change in lumbar lordosis (LL) between preoperative supine to standing radiographs and preoperative to postoperative alignment. Demographics and preoperative and postoperative sagittal alignment were similar between the Ost (n = 60, 65.9%) and NOst (n = 31, 34.1%) cohorts (p > 0.05). Of all Ost patients, 71.7% had a grade 2 osteotomy (mean 3 per patient), 21.7% had a grade 3 osteotomy, and 12.5% underwent both grade 3 and grade 2 osteotomies. Postoperatively, the NOst and Ost cohorts had similar pelvic incidence minus lumbar lordosis (PI-LL) mismatch (mean PI-LL 5.2° vs 1.2°; p = 0.205). Correction obtained through positioning (Sflex%) was significantly lower for in the osteotomy cohort (38.0% vs 76.3%, p = 0.004). A threshold of Sflex% < 70% predicted the need for osteotomy at a sensitivity of 78%, specificity of 56%, and positive predictive value of 77%. The flexibility of the spine is quantitatively related to the use of an osteotomy. Prospective studies are needed to determine thresholds that may be used to standardize surgical decision-making in ASD surgery.