Failure of nonoperative care in adult symptomatic lumbar scoliosis: incidence, timing, and risk factors for conversion from nonoperative to operative treatment.

OBJECTIVE: The Adult Symptomatic Lumbar Scoliosis (ASLS) study is a prospective multicenter trial with randomized and observational cohorts comparing operative and nonoperative treatment for ASLS. The objective of the present study was to perform a post hoc analysis of the ASLS trial to examine factors related to failure of nonoperative treatment in ASLS. METHODS: Patients from the ASLS trial who initially received at least 6 months of nonoperative treatment were followed for up to 8 years after trial enrollment. Baseline patient-reported outcome measures (Scoliosis Research Society-22 [SRS-22] questionnaire and Oswestry Disability Index), radiographic data, and other clinical characteristics were compared between patients who did and did not convert to operative treatment during follow-up. The incidence of operative treatment was calculated and independent predictors of operative treatment were identified using multivariate regression. RESULTS: Of 135 nonoperative patients, 42 (31%) crossed over to operative treatment after 6 months and 93 (69%) received only nonoperative treatment. In the observational cohort, 23 (22%) of 106 nonoperative patients crossed over to surgery. In the randomized cohort, 19 (66%) of 29 patients randomized to nonoperative treatment crossed over to surgery. The most impactful factors associated with crossover from nonoperative to operative treatment were enrollment in the randomized cohort and baseline SRS-22 subscore < 3.0 at the 2-year follow-up, closer to 3.4 at 8 years. In addition, baseline lumbar lordosis (LL) < 50° was associated with crossover to operative treatment. Each 1-point decrease in baseline SRS-22 subscore was associated with a 233% higher risk of conversion to surgery (hazard ratio [HR] 2.33, 95% confidence interval [CI] 1.14-4.76, p = 0.0212). Each 10° decrease in LL was associated with a 24% increased risk of conversion to operative treatment (HR 1.24, 95% CI 1.03-1.49, p = 0.0232). Enrollment in the randomized cohort was associated with a 337% higher probability of proceeding with operative treatment (HR 3.37, 95% CI 1.54-7.35, p = 0.0024). CONCLUSIONS: Enrollment in the randomized cohort, a lower baseline SRS-22 subscore, and lower LL were associated with conversion from nonoperative treatment to surgery in patients (observational and randomized) who were initially managed nonoperatively in the ASLS trial.

Mechanical complications and patient-reported outcome measures associated with high pelvic incidence and persistent pelvic retroversion: the Roussouly "false type 2" profile.

OBJECTIVE: The objective of this paper was to report mechanical complications and patient-reported outcome measures (PROMs) for adult spinal deformity (ASD) patients with a Roussouly "false type 2" (FT2) profile. METHODS: ASD patients treated from 2004 to 2014 at a single center were identified. Inclusion criteria were pelvic incidence ≥ 60° and a minimum 2-year follow-up. FT2 was defined as a high postoperative pelvic tilt (PT), as defined by the Global Alignment and Proportion target, and thoracic kyphosis < 30°. Mechanical complications, defined as proximal junctional kyphosis (PJK) and/or instrumentation failure, were determined and compared. Scoliosis Research Society-22r (SRS-22r) scores were compared between groups. RESULTS: Ninety-five patients (normal PT [NPT] group 49, FT2 group 46) who met the inclusion criteria were identified and studied. Most surgeries were revisions (NPT group 30 [61%], FT2 group 30 [65%]), and most were performed via a posterior-only approach (86%) (mean ± SD 9.6 ± 5 levels). Proximal junctional angles increased after surgery in both groups, without differences between groups. Neither rates of radiographic PJK (p = 0.10), revision for PJK (p = 0.45), nor revision for pseudarthrosis (p = 0.66) were different between groups. There were no differences between groups for SRS-22r domain scores or subscores. CONCLUSIONS: In this single-center experience, patients with high pelvic incidence fixed with persistent lumbopelvic parameter mismatch and engaged compensatory mechanisms (Roussouly FT2) had mechanical complications and PROMs not different from those with normalized alignment parameters. Compensatory PT may be acceptable in some cases of ASD surgery.

Proximal junctional failure in primary thoracolumbar fusion/fixation to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective multicenter cohort of 160 patients.

OBJECTIVE: Proximal junctional failure (PJF) is a severe form of proximal junctional kyphosis. Previous reports on PJF have been limited by heterogeneous cohorts and relatively short follow-ups. The authors' objectives herein were to identify risk factors for PJF and to assess its long-term incidence and revision rates in a homogeneous cohort. METHODS: The authors reviewed data from the Adult Symptomatic Lumbar Scoliosis 1 trial (ASLS-1), a National Institutes of Health-sponsored prospective multicenter study. Inclusion criteria were an age ≥ 40 years, ASLS (Cobb angle ≥ 30° and Oswestry Disability Index [ODI] ≥ 20 or Scoliosis Research Society revised 22-item questionnaire [SRS-22r] score ≤ 4.0 in pain, function, or self-image domains), and primary thoracolumbar fusion/fixation to the sacrum/pelvis of ≥ 7 levels. PJF was defined as a postoperative proximal junctional angle (PJA) change > 20°, fracture of the uppermost instrumented vertebra (UIV) or UIV+1 with > 20% vertebral height loss, spondylolisthesis of UIV/UIV+1 > 3 mm, or UIV screw dislodgment. RESULTS: One hundred sixty patients (141 women) were included in this analysis and had a median age of 62 years and a mean follow-up of 4.3 years (range 0.1-6.1 years). Forty-six patients (28.8%) had PJF at a median of 0.92 years (IQR 0.14, 1.23 years) following surgery. Based on Kaplan-Meier analyses, PJF rates at 1, 2, 3, and 4 years were 14.4%, 21.9%, 25.9%, and 27.4%, respectively. On univariate analysis, PJF was associated with greater age (p = 0.0316), greater body mass index (BMI; p = 0.0319), worse baseline patient-reported outcome measures (PROMs; ODI, SRS-22r, and SF-12 Physical Component Summary [PCS]; all p < 0.04), the use of posterior column osteotomies (PCOs; p = 0.0039), and greater postoperative thoracic kyphosis (TK; p = 0.0031) and PJA (p < 0.001). The use of UIV hooks was protective against PJF (p = 0.0340). On regression analysis (without postoperative measures), PJF was associated with greater BMI (HR 1.077, 95% CI 1.007-1.153, p = 0.0317), lower preoperative PJA (HR 0.607, 95% CI 0.407-0.906, p = 0.0146), and greater preoperative TK (HR 1.362, 95% CI 1.082-1.715, p = 0.0085). Patients with PJF had worse PROMs at the last follow-up (ODI, SRS-22r subscore and self-image, and SF-12 PCS; p < 0.04). Sixteen PJF patients (34.8%) underwent revision, and PJF recurred in 3 (18.8%). CONCLUSIONS: Among 160 primary ASLS patients with a median age of 62 years and predominant coronal deformity, the PJF rate was 28.8% at a mean 4.3-year follow-up, with a revision rate of 34.8%. On univariate analysis, PJF was associated with a greater age and BMI, worse baseline PROMs, the use of PCOs, and greater postoperative TK and PJA. The use of UIV hooks was protective against PJF. On multivariate analysis (without postoperative measures), a higher risk of PJF was associated with greater BMI and preoperative TK and lower preoperative PJA.

Rod fractures in thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective, multicenter cohort of 160 patients.

OBJECTIVE: Previous reports of rod fracture (RF) in adult spinal deformity are limited by heterogeneous cohorts, low follow-up rates, and relatively short follow-up durations. Since the majority of RFs present > 2 years after surgery, true occurrence and revision rates remain unclear. The objectives of this study were to better understand the risk factors for RF and assess its occurrence and revision rates following primary thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis (ASLS) in a prospective series with long-term follow-up. METHODS: Patient records were obtained from the Adult Symptomatic Lumbar Scoliosis-1 (ASLS-1) database, an NIH-sponsored multicenter, prospective study. Inclusion criteria were as follows: patients aged 40-80 years undergoing primary surgeries for ASLS (Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20 or Scoliosis Research Society-22r ≤ 4.0 in pain, function, and/or self-image) with instrumented fusion of ≥ 7 levels that included the sacrum/pelvis. Patients with and without RF were compared to assess risk factors for RF and revision surgery. RESULTS: Inclusion criteria were met by 160 patients (median age 62 years, IQR 55.7-67.9 years). At a median follow-up of 5.1 years (IQR 3.8-6.6 years), there were 92 RFs in 62 patients (38.8%). The median time to RF was 3.0 years (IQR 1.9-4.54 years), and 73% occurred > 2 years following surgery. Based on Kaplan-Meier analyses, estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Baseline radiographic, clinical, and demographic characteristics were similar between patients with and without RF. In Cox regression models, greater postoperative pelvic tilt (HR 1.895, 95% CI 1.196-3.002, p = 0.0065) and greater estimated blood loss (HR 1.02, 95% CI 1.005-1.036, p = 0.0088) were associated with increased risk of RF. Thirty-eight patients (61% of all RFs) underwent revision surgery. Bilateral RF was predictive of revision surgery (HR 3.52, 95% CI 1.8-6.9, p = 0.0002), while patients with unilateral nondisplaced RFs were less likely to require revision (HR 0.39, 95% CI 0.18-0.84, p = 0.016). CONCLUSIONS: This study provides what is to the authors' knowledge the highest-quality data to date on RF rates following ASLS surgery. At a median follow-up of 5.1 years, 38.8% of patients had at least one RF. Estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Greater estimated blood loss and postoperative pelvic tilt were significant risk factors for RF. These findings emphasize the importance of long-term follow-up to realize the true prevalence and cumulative incidence of RF.

The impact of lumbar alignment targets on mechanical complications after adult lumbar scoliosis surgery.

PURPOSE: The purpose of this study was to determine the discriminatory ability of age-adjusted alignment offset and the global alignment and proportion (GAP) score parameters to predict postoperative mechanical complications. METHODS: Surgical patients from the Adult Symptomatic Lumbar Scoliosis cohort were reviewed at 2 year follow up. Age-adjusted alignment offsets and GAP parameters were calculated for each patient. A series of nonlinear logistic regression models were fit, and the odds of mechanical complications were calculated. The discriminatory ability of the GAP score, GAP score parameters, and age-adjusted alignment offsets were determined plotting receiver operative characteristic (ROC) with the C statistic (AUC). RESULTS: A total of 165 patients were included. A total of 49 mechanical complications occurred in 41 patients (21 proximal junctional kyphosis and 28 pseudoarthrosis). The GAP score had no discriminatory ability in this cohort. Relative lumbar lordosis 15 degrees greater than ideal lumbar lordosis was associated with greater mechanical complications. A lumbar distribution index of 90% was associated with fewer mechanical complications compared to a lumbar distribution index of 65%. Age-adjusted offset alignment targets had no discriminatory ability to predict mechanical complications. CONCLUSION: Radiographic alignment targets using either age-adjusted alignment target offset or GAP score parameters had minimal ability to predict mechanical complications in isolation. Mechanical complications following adult spinal deformity surgery are complex, and patient factors play a critical role. Clinical trial registeration This study was registered at ClinicalTrials.gov (number NCT00854828) in March 2009.

Individual differences in postoperative recovery trajectories for adult symptomatic lumbar scoliosis.

OBJECTIVE: The Adult Symptomatic Lumbar Scoliosis-1 (ASLS-1) trial demonstrated the benefit of adult symptomatic lumbar scoliosis (ASLS) surgery. However, the extent to which individuals differ in their postoperative recovery trajectories is unknown. This study's objective was to evaluate variability in and factors moderating recovery trajectories after ASLS surgery. METHODS: The authors used longitudinal, multilevel models to analyze postoperative recovery trajectories following ASLS surgery. Study outcomes included the Oswestry Disability Index (ODI) score and Scoliosis Research Society-22 (SRS-22) subscore, which were measured every 3 months until 2 years postoperatively. The authors evaluated the influence of preoperative disability level, along with other potential trajectory moderators, including radiographic, comorbidity, pain/function, demographic, and surgical factors. The impact of different parameters was measured using the R2, which represented the amount of variability in ODI/SRS-22 explained by each model. The R2 ranged from 0 (no variability explained) to 1 (100% of variability explained). RESULTS: Among 178 patients, there was substantial variability in recovery trajectories. Applying the average trajectory to each patient explained only 15% of the variability in ODI and 21% of the variability in SRS-22 subscore. Differences in preoperative disability (ODI/SRS-22) had the strongest influence on recovery trajectories, with patients having moderate disability experiencing the greatest and most rapid improvement after surgery. Reflecting this impact, accounting for the preoperative ODI/SRS-22 level explained an additional 56%-57% of variability in recovery trajectory, while differences in the rate of postoperative change explained another 7%-9%. Among the effect moderators tested, pain/function variables-such as visual analog scale back pain score-had the biggest impact, explaining 21%-25% of variability in trajectories. Radiographic parameters were the least influential, explaining only 3%-6% more variance than models with time alone. The authors identified several significant trajectory moderators in the final model, such as significant adverse events and the number of levels fused. CONCLUSIONS: ASLS patients have highly variable postoperative recovery trajectories, although most reach steady state at 12 months. Preoperative disability was the most important influence, although other factors, such as number of levels fused, also impacted recovery.

Patient-reported outcome measure clustering after surgery for adult symptomatic lumbar scoliosis.

OBJECTIVE: Adult symptomatic lumbar scoliosis (ASLS) is a widespread and debilitating subset of adult spinal deformity. Although many patients benefit from operative treatment, surgery entails substantial cost and risk for adverse events. Patient-reported outcome measures (PROMs) are patient-centered tools used to evaluate the appropriateness of surgery and to assist in the shared decision-making process. Framing realistic patient expectations should include the possible functional limitation to improvement inherent in surgical intervention, such as multilevel fusion to the sacrum. The authors' objective was to predict postoperative ASLS PROMs by using clustering analysis, generalized longitudinal regression models, percentile analysis, and clinical improvement analysis of preoperative health-related quality-of-life scores for use in surgical counseling. METHODS: Operative results from the combined ASLS cohorts were examined. PROM score clustering after surgery investigated limits of surgical improvement. Patients were categorized by baseline disability (mild, moderate, moderate to severe, or severe) according to preoperative Scoliosis Research Society (SRS)-22 and Oswestry Disability Index (ODI) scores. Responder analysis for patients achieving improvement meeting the minimum clinically important difference (MCID) and substantial clinical benefit (SCB) standards was performed using both fixed-threshold and patient-specific values (MCID = 30% of remaining scale, SCB = 50%). Best (top 5%), worst (bottom 5%), and median scores were calculated across disability categories. RESULTS: A total of 171/187 (91%) of patients with ASLS achieved 2-year follow-up. Patients rarely achieved a PROM ceiling for any measure, with 33%-43% of individuals clustering near 4.0 for SRS domains. Patients with severe baseline disability (< 2.0) SRS-pain and SRS-function scores were often left with moderate to severe disability (2.0-2.9), unlike patients with higher (≥ 3.0) initial PROM values. Patients with mild disability according to baseline SRS-function score were unlikely to improve. Crippling baseline ODI disability (> 60) commonly left patients with moderate disability (median ODI = 32). As baseline ODI disability increased, patients were more likely to achieve MCID and SCB (p < 0.001). Compared to fixed threshold values for MCID and SCB, patient-specific values were more sensitive to change for patients with minimal ODI baseline disability (p = 0.008) and less sensitive to change for patients with moderate to severe SRS subscore disability (p = 0.01). CONCLUSIONS: These findings suggest that ASLS surgeries have a limit to possible improvement, probably due to both baseline disability and the effects of surgery. The most disabled patients often had moderate to severe disability (SRS < 3, ODI > 30) at 2 years, emphasizing the importance of patient counseling and expectation management.

Orthopedic disease burden in adult patients with symptomatic lumbar scoliosis: results from a prospective multicenter study.

OBJECTIVE: Although the health impact of adult symptomatic lumbar scoliosis (ASLS) is substantial, these patients often have other orthopedic problems that have not been previously quantified. The objective of this study was to assess disease burden of other orthopedic conditions in patients with ASLS based on a retrospective review of a prospective multicenter cohort. METHODS: The ASLS-1 study is an NIH-sponsored prospective multicenter study designed to assess operative versus nonoperative treatment for ASLS. Patients were 40-80 years old with ASLS, defined as a lumbar coronal Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20, or Scoliosis Research Society-22 questionnaire score ≤ 4.0 in pain, function, and/or self-image domains. Nonthoracolumbar orthopedic events, defined as fractures and other orthopedic conditions receiving surgical treatment, were assessed from enrollment to the 4-year follow-up. RESULTS: Two hundred eighty-six patients (mean age 60.3 years, 90% women) were enrolled, with 173 operative and 113 nonoperative patients, and 81% with 4-year follow-up data. At a mean (± SD) follow-up of 3.8 ± 0.9 years, 104 nonthoracolumbar orthopedic events were reported, affecting 69 patients (24.1%). The most common events were arthroplasty (n = 38), fracture (n = 25), joint ligament/cartilage repair (n = 13), and cervical decompression/fusion (n = 7). Based on the final adjusted model, patients with a nonthoracolumbar orthopedic event were older (HR 1.44 per decade, 95% CI 1.07-1.94), more likely to have a history of tobacco use (HR 1.63, 95% CI 1.00-2.66), and had worse baseline leg pain scores (HR 1.10, 95% CI 1.01-1.19). CONCLUSIONS: Patients with ASLS have high orthopedic disease burden, with almost 25% having a fracture or nonthoracolumbar orthopedic condition requiring surgical treatment during the mean 3.8 years following enrollment. Comparisons with previous studies suggest that the rate of total knee arthroplasty was considerably greater and the rates of total hip arthroplasty were at least as high in the ASLS-1 cohort compared with the similarly aged general US population. These conditions may further impact health-related quality of life and outcomes assessments of both nonoperative and operative treatment approaches in patients with ASLS.

Operative versus nonoperative treatment for adult symptomatic lumbar scoliosis at 5-year follow-up: durability of outcomes and impact of treatment-related serious adverse events.

OBJECTIVE: Although short-term adult symptomatic lumbar scoliosis (ASLS) studies favor operative over nonoperative treatment, longer outcomes are critical for assessment of treatment durability, especially for operative treatment, because the majority of implant failures and nonunions present between 2 and 5 years after surgery. The objectives of this study were to assess the durability of treatment outcomes for operative versus nonoperative treatment of ASLS, to report the rates and types of associated serious adverse events (SAEs), and to determine the potential impact of treatment-related SAEs on outcomes. METHODS: The ASLS-1 (Adult Symptomatic Lumbar Scoliosis-1) trial is an NIH-sponsored multicenter prospective study to assess operative versus nonoperative ASLS treatment. Patients were 40-80 years of age and had ASLS (Cobb angle ≥ 30° and Oswestry Disability Index [ODI] ≥ 20 or Scoliosis Research Society [SRS]-22 subscore ≤ 4.0 in the Pain, Function, and/or Self-Image domains). Patients receiving operative and nonoperative treatment were compared using as-treated analysis, and the impact of related SAEs was assessed. Primary outcome measures were ODI and SRS-22. RESULTS: The 286 patients with ASLS (107 with nonoperative treatment, 179 with operative treatment) had 2-year and 5-year follow-up rates of 90% (n = 256) and 74% (n = 211), respectively. At 5 years, compared with patients treated nonoperatively, those who underwent surgery had greater improvement in ODI (mean difference -15.2 [95% CI -18.7 to -11.7]) and SRS-22 subscore (mean difference 0.63 [95% CI 0.48-0.78]) (p < 0.001), with treatment effects (TEs) exceeding the minimum detectable measurement difference (MDMD) for ODI (7) and SRS-22 subscore (0.4). TEs at 5 years remained as favorable as 2-year TEs (ODI -13.9, SRS-22 0.52). For patients in the operative group, the incidence rates of treatment-related SAEs during the first 2 years and 2-5 years after surgery were 22.38 and 8.17 per 100 person-years, respectively. At 5 years, patients in the operative group who had 1 treatment-related SAE still had significantly greater improvement, with TEs (ODI -12.2, SRS-22 0.53; p < 0.001) exceeding the MDMD. Twelve patients who received surgery and who had 2 or more treatment-related SAEs had greater improvement than nonsurgically treated patients based on ODI (TE -8.34, p = 0.017) and SRS-22 (TE 0.32, p = 0.029), but the SRS-22 TE did not exceed the MDMD. CONCLUSIONS: The significantly greater improvement of operative versus nonoperative treatment for ASLS at 2 years was durably maintained at the 5-year follow-up. Patients in the operative cohort with a treatment-related SAE still had greater improvement than patients in the nonoperative cohort. These findings have important implications for patient counseling and future cost-effectiveness assessments.

The role of the fractional lumbosacral curve in persistent coronal malalignment following adult thoracolumbar deformity surgery: a radiographic analysis.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: Assess radiographically the effect of an all-posterior approach on correction of coronal balance in primary adult thoracolumbar spinal deformities based on Bao's classification of coronal imbalance with a focus on lumbosacral curve correction. Achieving appropriate coronal alignment is difficult in adults with coronal malalignment due to trunk shift ipsilateral to degenerated thoracolumbar scoliosis' apex. METHODS: Review of adults who underwent posterior spinal fusions to pelvis (≥ 5 levels) for thoracolumbar scoliosis. Exclusion: revisions, no coronal deformity, thoracic Cobb > 30°, and anterior operations. Patients were divided into three groups, as proposed by Bao et al.: type A: CSVL < 3 cm; type B: CSVL > 3 cm and C7 plumb shifted to scoliosis' concavity; type C: CSVL > 3 cm and C7 plumb shifted to scoliosis' convexity. Radiographic parameters and surgical techniques were compared. RESULTS: 124 patients (male-6; female-118; avg. age 58 ± 10 years; type A-87; type B-19; type C-18). Type C had significantly greater lumbosacral fractional curves. 28% of type C were treated with fractional curve TLIFs, while all, but one, type B had TLIFs of the fractional curve. Deformity parameters after surgery were similar, except type C had persistently greater fractional curves/coronal malalignment. All preop type B were appropriately corrected postop. For preop type C, 67% remained type C and 33% became type A postop. Compared to those who became type A, persistently undercorrected and malaligned (type C) patients had significantly greater preop lumbosacral fractional curves, greater preop coronal Cobb angles, and more commonly involved TLIFs of lumbosacral fractional curves. Compared to no interbody support, use of TLIFs provided better correction of the lumbosacral curve. CONCLUSIONS: In adults with primary, posterior-only operations for thoracolumbar spinal deformity, 67% of type C coronal deformities and 20% of type A deformities remained or had worse coronal malalignment postop. While the use of TLIFs improved correction of the lumbosacral curve compared to no interbody support, alternative surgical strategies should be considered to more adequately correct lumbosacral fractional curves and balance correction of lumbosacral and major thoracolumbar curves so as to maintain and/or restore coronal balance. LEVEL OF EVIDENCE: III.

Rod fractures and nonunions after long fusion to the sacrum for primary presentation adult spinal deformity: a comparison with and without interbody fusion in the distal lumbar spine.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To investigate the prevalence and incidence rate of rod fractures (RF) in patients undergoing surgery for correction of adult spinal deformity (ASD) with or without the use of interbody fusions in the caudal levels of the fusion construct. BACKGROUND: Data: Pseudarthrosis and rod fracture after long spinal fusion to the sacrum for correction of ASD remain a concern. METHODS: We reviewed clinical records of patients who underwent surgery for correction of ASD between 2004 and 2014. All cases were primary (no prior spine fusion) surgeries with long fusion to the sacrum and bilateral spinopelvic fixation. Patients were dichotomized into one of two groups based on whether an interbody fusion was performed at the caudal levels of the fusion construct. The primary outcome of interest was the prevalence and incidence rate of RFs. RESULTS: A total of 230 patients underwent a long segment fusion for correction of ASD with mean follow-up of 55 months. 117 patients had an interbody fusion (IF) while 113 patients did not (NIF). At last follow-up, there was no significant difference in the prevalence of RFs between the cohort of patients IF vs NIF (IF cohort: n = 20, 17.9% vs NIF cohort: n = 15, 14.2%, p = 0.49). However, the incidence rate for bilateral rod fractures was 1.6%/year for IF group vs 1.0%/year for NIF group (p = 0.02). Location of RF was different between the two groups; RF (unilateral and bilateral) above L4 was the most common location in the IF group (n = 17/20; 85%) compared to L4-S1 in the NIF group (n = 11/15; 73%) (p = 0.02). CONCLUSION: Interbody fusion does not fully protect against rod failure in the lumbar spine in ASD patients with long posterior spinal fusion and may encourage failure at L2-L4, the levels above the interbody fusion. LEVEL OF EVIDENCE: III.

Differences in Functional Treadmill Tests in Patients With Adult Symptomatic Lumbar Scoliosis Treated Operatively and Nonoperatively.

STUDY DESIGN: Prospective longitudinal cohort. OBJECTIVES: The aim of this study was to determine whether functional treadmill testing (FTT) demonstrates differences between patients treated operatively and nonoperatively for adult symptomatic lumbar scoliosis (ASLS). SUMMARY OF BACKGROUND DATA: ASLS has become increasingly prevalent as the population ages. ASLS can be accompanied by neurogenic claudication, leading to difficulty walking. FTT may provide a functional tool to evaluate patients with ASLS. METHODS: One hundred and eighty-seven patients who underwent nonoperative (n = 88) or operative treatment (n = 99) of ASLS with complete baseline and 2-year post-treatment FTTs and concurrent patient-reported outcomes were identified. FTT parameters included maximum speed, time to onset of symptoms, distance ambulated, time ambulated, and Back and Leg pain severity before and after testing. RESULTS: At baseline, patients treated operatively reported worse post-FTT back pain (4.39 vs. 3.45, P = 0.032) than those treated nonoperatively, despite similar ODI, SRS-22 Pain and Activity domain scores. Mean time ambulated (+2.15 vs. -1.20 P = 0.001), pre-FTT back pain (+0.19 vs. -1.60, P < 0.000) and leg pain (+0.25 vs. -0.54, P = 0.024) improved in the operative group but deteriorated in the nonoperative group. On the 2-year follow-up FTT, both groups showed improvement in post-FTT back pain (-0.53 vs. -2.64, P < 0.000) and leg pain (-0.13 vs. -1.54, P = 0.001) severity but the improvement was statistically significantly greater in the operative compared to the nonoperative group. CONCLUSION: FTT results at baseline were worse in patients treated operatively than those treated non-operatively. FTT may be a useful adjunct to assess treatment outcomes in patients with ASLS and may help surgeons counsel patients regarding expectations 2 years after operative or nonoperative treatment for ASLS. At 2-year follow-up, time ambulated deteriorated in patients treated nonoperatively but improved in patients treated operatively. Although both groups showed improvement in post-FTT Back and Leg pain at 2 years, the improvement was greater in the operative compared to the nonoperative group. LEVEL OF EVIDENCE: 2.

Comprehensive classification system for multirod constructs across three-column osteotomies: a reliability study.

OBJECTIVE: In this study, the authors' goal was to determine the intra- and interobserver reliability of a new classification system that allows the description of all possible constructs used across three-column osteotomies (3COs) in terms of rod configuration and density. METHODS: Thirty-five patients with multirod constructs (MRCs) across a 3CO were classified by two spinal surgery fellows according to the new system, and then were reclassified 2 weeks later. Constructs were classified as follows: the number of rods across the osteotomy site followed by a letter corresponding to the type of rod configuration: "M" is for a main rod configuration, defined as a single rod spanning the osteotomy. "L" is for linked rod configurations, defined as 2 rods directly connected to each other at the osteotomy site. "S" is for satellite rod configurations, which were defined as a short rod independent of the main rod with anchors above and below the 3CO. "A" is for accessory rods, defined as an additional rod across the 3CO attached to main rods but not attached to any anchors across the osteotomy site. "I" is for intercalary rod configurations, defined as a rod connecting 2 separate constructs across the 3CO, without the intercalary rod itself attached to any anchors across the osteotomy site. The intra- and interobserver reliability of this classification system was determined. RESULTS: A sample estimation for validation assuming two readers and 35 subjects results in a two-sided 95% confidence interval with a width of 0.19 and a kappa value of 0.8 (SD 0.3). The Fleiss kappa coefficient (κ) was used to calculate the degree of agreement between interrater and intraobserver reliability. The interrater kappa coefficient was 0.3, and the intrarater kappa coefficient was 0.63 (good reliability). This scenario represents a high degree of agreement despite a low kappa coefficient. Correct observations by both observers were 34 of 35 and 33 of 35 at both time points. Misclassification was related to difficulty in determining connectors versus anchors. CONCLUSIONS: MRCs across 3COs have variable rod configurations. Currently, no classification system or agreement on nomenclature exists to define the configuration of rods across 3COs. The authors present a new, comprehensive MRC classification system with good inter- and intraobserver reliability and a high degree of agreement that allows for a standardized description of MRCs across 3COs.

Cost-effectiveness of adult lumbar scoliosis surgery: an as-treated analysis from the adult symptomatic scoliosis surgery trial with 5-year follow-up.

STUDY DESIGN: Longitudinal comparative cohort. OBJECTIVE: The purpose of this study is to report on the cost-effectiveness of surgical versus non-surgical treatment for Adult Symptomatic Lumbar Scoliosis (ASLS) using the as-treated data and provide a comparison to previously reported intent-to-treat (ITT) analysis. Adult spinal deformity is a relatively prevalent condition for which surgical treatment has become increasingly common but concerns surrounding complications, revision rates and cost-effectiveness remain unresolved. Of these issues, cost-effectiveness is perhaps the most difficult to quantify as the requisite data is difficult to obtain. The purpose of this study is to report on the cost-effectiveness of surgical versus non-surgical treatment for ASLS using the as-treated data and provide a comparison to previously reported ITT analysis. METHODS: Patients with at least 5-year follow-up data within the same treatment arm were included. Data collected every 3 months included use of nonoperative modalities, medications and employment status. Costs for surgeries and non-operative modalities were determined using Medicare Allowable rates. Medication costs were determined using the RedBook and indirect costs were calculated based on the reported employment status and income. Quality-Adjusted Life Years (QALY) was determined using the SF-6D. RESULTS: Of 226 patients, 195 patients (73 Non-op, 122 Op) met inclusion criteria. At 5 years, 29 (24%) patients in the Op group had a revision surgery of whom two had two revisions and one had three revisions. The cumulative cost for the Op group was $111,451 with a cumulative QALY gain of 2.3. The cumulative cost for the Non-Op group was $29,124 with a cumulative QALY gain of 0.4. This results in an ICER of $44,033 in favor of Op treatment. CONCLUSION: This as-treated cost-effectiveness analysis demonstrates that surgical treatment for adult lumbar scoliosis becomes favorable at year-three, 1 year earlier than suggested by a previous intent-to-treat analysis. LEVEL OF EVIDENCE: II.

Relationship of the character of rod fractures on outcomes following long thoracolumbar fusion to the sacrum for adult spinal deformity.

BACKGROUND CONTEXT: Rod fractures (RF) and pseudarthrosis are a frequent occurrence after adult spinal deformity (ASD) surgery and may be problematic. However, not all RF signal nonunion and cause clinical concern. An improved understanding of the sequelae after RF occurrence is valuable for further management. PURPOSE: To characterize the radiographic findings, clinical outcomes, and revision rates between patients who developed unilateral RF (URF) and bilateral RF (BRF) following thoracolumbar posterior spinal fusions to the sacrum for ASD and identify patient characteristics associated with clinically significant RF that lead to subsequent revision surgeries and detection of nonunion. STUDY DESIGN/SETTING: A retrospective single-center cohort study was performed. PATIENT SAMPLE: Patients undergoing long-construct posterior spinal fusions to the sacrum performed at a single institution from 2004 to 2014 and developed a RF postoperatively were included. OUTCOME MEASURES: Patient demographics, radiographic parameters, surgical data, Oswestry Disability Index (ODI), Scoliosis Research Society-22 (SRS-22), and revision rates. METHODS: Inclusion criteria were ASD patients age >18 who had ≥5 vertebrae instrumented and fused posteriorly to the sacrum and development of RF. Data were compared among patients: who developed unilateral-nondisplaced RF (UNRF), unilateral-displaced RF (UDRF), bilateral-nondisplaced RF and bilateral-displaced RF (BDRF) at baseline and follow-up. ODI and SRS-22 scores were assessed at baseline, 1 year postoperatively, the time of RF occurrence, and latest follow-up. RESULTS: Of 526 patients who met inclusion criteria, 96 (18.3%) developed RF (URF n=70 [73%]; BRF n=26 [27%]). Preoperative demographics and surgical parameters were similar between the groups. BRF patients had substantial loss of sagittal correction from 1-year postoperatively to the time of RF, including loss of sagittal vertical axis (4.8 cm vs. 2.2 cm; p<.001), loss of lumbar lordosis (14.8° vs. 4.9°; p=.010) and loss of pelvic incidence minus lumbar lordosis mismatch (PI-LL) mismatch (5.0° vs. 14.6°; p=.020) compared with those of URF patients. The BDRF group had more loss of ODI scores (13.4 vs. 4.2; p=.013), SRS pain score (0.8 vs. 0.2; p=.024), SRS function score (0.3 vs. 0; p=.020) and SRS subscore (0.4 vs. 0.1; p=.148) from 1-year postoperatively to the time of RF and underwent revision surgery more often than the UNRF group (87.5% vs. 4.8%; p<.0001). At final follow-up (median 2.8 years, range 1-10.3 years after RF detection), URF patients who did not undergo revision surgeries still maintained equivalent sagittal alignment correction (sagittal vertical axis, LL and PI-LL; all p>.05) and had similar, not worse, mean ODI scores, SRS Subscore and SRS pain compared with the time at RF and 1-year follow-up. CONCLUSIONS: RF are not uncommon after ASD operations. Asymptomatic, UNRF in our study did not jeopardize clinical outcomes or radiographic alignment parameters and, in most cases, did not represent a nonunion, as opposed to BRF. BRF patients exhibited loss of sagittal correction, loss of clinical outcome improvements, as measured by ODI, SRS pain and SRS Subscore at the time of RF, and were revised more often than URF patients.

Effect modifiers for patient-reported outcomes in operatively and nonoperatively treated patients with adult symptomatic lumbar scoliosis: a combined analysis of randomized and observational cohorts.

OBJECTIVE: Adult symptomatic lumbar scoliosis (ASLS) is a common and disabling condition. The ASLS-1 was a multicenter, dual-arm study (with randomized and observational cohorts) examining operative and nonoperative care on health-related quality of life in ASLS. An aim of ASLS-1 was to determine patient and radiographic factors that modify the effect of operative treatment for ASLS. METHODS: Patients 40-80 years old with ASLS were enrolled in randomized and observational cohorts at 9 North American centers. Primary outcomes were the differences in mean change from baseline to 2-year follow-up for the SRS-22 subscore (SRS-SS) and the Oswestry Disability Index (ODI). Analyses were performed using an as-treated approach with combined cohorts. Factors examined were prespecified or determined using regression tree analysis. For each potential effect modifier, subgroups were created using clinically relevant cutoffs or via regression trees. Estimates of within-group and between-group change were compared using generalized linear mixed models. An effect modifier was defined as a treatment effect difference greater than the minimal detectable measurement difference for both SRS-SS (0.4) and ODI (7). RESULTS: Two hundred eighty-six patients were enrolled and 256 (90%) completed 2-year follow-up; 171 received operative treatment and 115 received nonoperative treatment. Surgery was superior to nonoperative care for all effect subgroups considered, with the exception of those with nearly normal pelvic incidence-lumbar lordosis (PI-LL) match (≤ 11°). Male patients and patients with more (> 11°) PI-LL mismatch at baseline had greater operative treatment effects on both the SRS-SS and ODI compared to nonoperative treatment. No other radiographic subgroups were associated with treatment effects. High BMI, lower socioeconomic status, and poor mental health were not related to worse outcomes. CONCLUSIONS: Numerous factors previously related to poor outcomes with surgery, such as low mental health, lower socioeconomic status, and high BMI, were not related to outcomes in ASLS in this exploratory analysis. Those patients with higher PI-LL mismatch did improve more with surgery than those with normal alignment. On average, none of the factors considered were associated with a worse outcome with operative treatment versus nonoperative treatment. These findings may guide future prospective analyses of factors related to outcomes in ASLS care.

Reaching minimal clinically important difference in adult spinal deformity surgery: a comparison of patients from North America and Japan.

OBJECTIVE: The Scoliosis Research Society-22r questionnaire (SRS-22r) has been shown to be reliable, valid, and responsive to change in patients with adult spinal deformity (ASD) undergoing surgery. The minimal clinically important difference (MCID) is the smallest difference in a health-related quality of life score that is considered to be worthwhile or clinically important to the individual. The authors hypothesized that the proportion of patients with ASD achieving an MCID in the SRS-22r score would be different between two culturally different cohorts. The purpose of this study was to compare the proportion of patients with ASD achieving MCID for the SRS-22r domains in North American (NA) and Japanese cohorts. METHODS: A total of 137 patients from North America (123 women, mean age 60.0 years) and 60 patients from Japan (56 women, mean age 65.5 years) with at least 2 years of follow-up after corrective spine surgery for ASD were included. Except for self-image, published Japanese MCID values of SRS-22r for ASD were higher (function = 0.90, pain = 0.85, self-image = 1.05, subtotal = 1.05) than the published NA MCID values (function = 0.60, pain = 0.40, self-image = 1.23, subtotal = 0.43). RESULTS: There was a statistically significant improvement in all SRS-22r domain scores at 2 years compared to baseline in both cohorts. Except for mental health (NA = 0.32, Japanese = 0.72, p = 0.005), the mean improvement from baseline to 2 years was similar between the NA and Japanese cohorts. The proportion of patients achieving MCID was higher in North America for function (NA = 51%, Japanese = 30%, p = 0.006), pain (NA = 80%, Japanese = 47%, p < 0.001), and subtotal (NA = 72%, Japanese = 35%, p < 0.001), while there was no significant difference for self-image (NA = 53%, Japanese = 58%, p = 0.454). CONCLUSIONS: Despite similar improvements in SRS-22r domain scores from baseline to 2 years postoperatively, the proportion of patients reaching SRS-22r MCID for function, pain, and subtotal after ASD surgery was higher in the NA cohort than in the Japanese cohort. This may imply that patients in North America and Japan may value observed changes in clinical status differently.

Comparison of rod fracture rates in long spinal deformity constructs after transforaminal versus anterior lumbar interbody fusions: a single-institution analysis.

OBJECTIVE: Pseudarthrosis is a common complication of long-segment fusions after surgery for correction of adult spinal deformity (ASD). Interbody fusions are frequently used at the caudal levels of long-segment spinal deformity constructs as adjuncts for anterior column support. There is a paucity of literature comparing rod fracture rates (proxy for pseudarthrosis) in patients undergoing transforaminal lumbar interbody fusion (TLIF) versus anterior lumbar interbody fusion (ALIF) at the caudal levels of the long spinal deformity construct. In this study the authors sought to compare rod fracture rates in patients undergoing surgery for correction of ASD with TLIF versus ALIF at the caudal levels of long spinal deformity constructs. METHODS: We reviewed clinical records of patients who underwent surgery for correction of ASD between 2008 and 2014 at a single institution. Data including demographics, comorbidities, and indications for surgery, as well as postoperative variables, were collected for each patient. All patients had a minimum 2-year follow-up. Patients were dichotomized into two groups for comparison on the basis of undergoing a TLIF versus an ALIF procedure at the caudal levels of long spinal deformity constructs. The primary outcome of interest was the rate of rod fractures. RESULTS: A total of 198 patients (TLIF 133 patients; ALIF 65 patients) underwent a long-segment fusion to the sacrum with iliac fixation. The mean ± standard deviation follow-up period was 62.23 ± 29.26 months. Baseline demographic variables were similar in both patient groups. There were no significant differences between groups in the severity of the baseline sagittal plane deformity (i.e., baseline lumbar-pelvic parameters) or the final deformity correction achieved. Mean total recombinant human bone morphogenetic protein 2 (rhBMP-2) dose for L1-sacrum fusion was significantly higher in the ALIF (100 mg) than in the TLIF (62 mg) group. The overall rod failure rate (cases with rod fracture/total cases) within this case series was 19.19% (38/198); 10.60% (21/198) were unilateral rod fractures and 8.58% (17/198) were bilateral rod fractures. At last clinical follow-up, there were no statistically significant differences in bilateral rod fracture rates between the group of patients who had a TLIF procedure and the group who had an ALIF procedure at the caudal levels of the long spinal deformity constructs (TLIF 10.52% vs ALIF 4.61%, p = 0.11). However, the incidence rate (cases per patient follow-up years) for bilateral rod fractures was significantly higher in the TLIF than in the ALIF cohort (TLIF 2.20% vs ALIF 0.70%, p < 0.0001). The reoperation rate for rod fractures was similar between the patient groups (p = 0.40). CONCLUSIONS: Although both ALIF and TLIF procedures at the caudal levels of long spinal deformity constructs achieved similar and satisfactory deformity correction, ALIFs were associated with a lower rod fracture incidence rate. There were no differences between groups in the prevalence of rod fracture or revision surgery, however, and both groups had low bilateral rod fracture prevalence and incidence rates. One technique is not clearly superior to the other.

Cost-effectiveness of Operative versus Nonoperative Treatment of Adult Symptomatic Lumbar Scoliosis an Intent-to-treat Analysis at 5-year Follow-up.

STUDY DESIGN: Secondary analysis using data from the NIH-sponsored study on adult symptomatic lumbar scoliosis (ASLS) that included randomized and observational arms. OBJECTIVE: The aim of this study was to perform an intent-to-treat cost-effectiveness study comparing operative (Op) versus nonoperative (NonOp) care for ASLS. SUMMARY OF BACKGROUND DATA: The appropriate treatment approach for ASLS continues to be ill-defined. NonOp care has not been shown to improve outcomes. Surgical treatment has been shown to improve outcomes, but is costly with high revision rates. METHODS: Patients with at least 5-year follow-up data were included. Data collected every 3 months included use of NonOp modalities, medications, and employment status. Costs for index and revision surgeries and NonOp modalities were determined using Medicare Allowable rates. Medication costs were determined using the RedBook and indirect costs were calculated based on reported employment status and income. Qualityadjusted life year (QALY) was determined using the SF6D. RESULTS: There were 81 of 95 cases in the Op and 81 of 95 in the NonOp group with complete 5-year follow-up data. Not all patients were eligible 5-year follow-up at the time of the analysis. All patients in the Op and 24 (30%) in the NonOp group had surgery by 5 years. At 5 years, the cumulative cost for Op was $96,000 with a QALY gain of 2.44 and for NonOp the cumulative cost was $49,546 with a QALY gain of 0.75 with an incremental cost-effectiveness ratio (ICER) of $27,480 per QALY gain. CONCLUSION: In an intent-to-treat analysis, neither treatment was dominant, as the greater gains in QALY in the surgery group come at a greater cost. The ICER for Op compared to NonOp treatment was above the threshold generally considered cost-effective in the first 3 years of the study but improved over time and was highly cost-effective at 4 and 5 years. LEVEL OF EVIDENCE: 2.