Khaled M. Kebaish

BACKGROUND AND OBJECTIVES: Postoperative thoracolumbar (TL) realignment in patients with adult spinal deformity (ASD) may induce cervical spine (CS) decompensation. This study identifies predictors of CS decompensation after TL surgery and defines a baseline CS-alignment threshold based on C2-pelvic angle (C2-PA) for CS inclusion in the TL construct. METHODS: Patients with ASD undergoing TL fusion to the sacrum with an upper instrumented vertebrae at T2 or below and available baseline radiographs and patient-reported outcome measures (PROMs) were included. CS decompensation was defined as CS surgery or >2 SD above the mean in C2-PA, cervical sagittal vertical axis (cSVA), or T1-slope cervical lordosis (TS-CL) at the studied postoperative time point. RESULTS: One thousand one hundred ninety patients were included; 166 (13.9%) had CS decompensation after TL surgery, including 24 (2.0%) requiring CS extension. CS decompensation was identified in 81 patients (6.8%) at 6 weeks (4 (0.3%) extensions), 13 (1.2%) at 6 months (2 (0.2%)), 43 (3.9%) at 1 year (7 (0.6%)), and 29 (2.8%) at 2 years (11 (0.9%)). Patients with CS decompensation at 6 months showed worse global and CS alignment at 6 weeks (lumbar lordosis: 53.6 vs 46.3; cSVA: 30.5 vs 38.5; P < .05). CS decompensation at 1 year was associated with worse PROMs (physical component score: 39.0 vs 35.4; Scoliosis research society score: 3.6 vs 3.3; P < .05). CS decompensation at 2 years was associated with worse CS alignment at 1 year (TS-CL: 20.8 vs 28.6; cSVA: 31.1 vs 37.8) and worse PROMs at 2 years. Higher baseline C2-PA was associated with shorter time to CS decompensation. Cox modeling identified baseline C2-PA (hazard ratio [HR] 1.05, 95% CI, 1.03-1.06), TS-CL (HR 1.05, 95% CI, 1.03-1.06), surgical invasiveness (HR 0.99, 95% CI, 0.98-0.99), and upper thoracic instrumentation (HR 2.9, 95% CI, 1.8-4.7) as predictors of CS decompensation, with a C2-PA threshold of 26.2°. CONCLUSION: Two years after TL ASD surgery, 13.9% had CS decompensation, with 14% requiring CS extension. Baseline CS alignment independently predicted CS decompensation. Patients with preoperative C2-PA >26.2° may benefit from CS inclusion in the TL construct after external validation of this threshold by future research.

Introduction Predicting post-operative changes in thoracic kyphosis (TK) remains challenging in adult spinal deformity (ASD) surgery. This study aimed to quantify both iatrogenic and reciprocal changes in TK following lumbar correction and assess their maintenance at 2-year follow-up. Methods A retrospective analysis was performed on 356 ASD patients treated with posterior instrumentation from T9–11 to the pelvis, with a minimum 2-year follow-up. TK values were compared with normative data. Multivariate analysis identified thoracolumbar parameters associated with reciprocal thoracic changes and proximal failure. Results Pre-op TK (median 34°) was normal for 59.8% and hypokyphotic for 39.0% of patients. At 6 weeks, 79.1% of initially hypokyphotic patients normalized, while 11.3% of normokyphotic patients deteriorated. Postoperative TK increase correlated with lumbar lordosis gain (p15°, and 9.6% required proximal extension for junctional issues—defined collectively as “thoracic failures” (17.4%). Independent predictors of failure included advanced age (OR 3.6), more proximal lumbar correction (OR 1.9), and pronounced early mid-thoracic kyphosis (OR 2.3). Conclusion In ASD surgery with Upper Instrumented Vertebra (UIV) between T9 and T11, changes in TK were largely proportional to lumbar correction, leading to normalization in most cases. However, age, the location of lumbar correction, and early post-operative thoracic shape independently predicted thoracic failure, highlighting the need for tailored alignment strategies.

Study Design.: Retrospective analysis of a multicenter complex adult spinal deformity (ASD) cohort. Objectives.: Develop a simplified, weighted, and modifiable ASD Frailty Index (o-ASD-FI) that incorporates modifiable health components. Background.: Though newer frailty indices have emerged, none specifically addresses complex ASD while incorporating modifiable health factors. Methods.: Miller’s ASD-FI variables were evaluated via Pearson bivariate correlation and multiple stepwise regression. Ten frailty and three modifiable health factors (depression, diabetes, and osteoporosis) were identified and regressed against mortality, extended length of stay (LOS > 8 d), revisions, and major complications. Coefficients were weighted using Johnson’s method to create the o-ASD-FI (range: 0 – 18). Frailty categories were defined as: not frail (P P P P <0.01. Conclusions.: The newly developed simplified, weighted, and optimizable ASD Frailty Index (o-ASD-FI) incorporates modifiable health components, providing a robust assessment of physiological status and potentially superior risk stratification compared with existing tools for both primary and revision complex spinal deformity surgery. Level of Evidence: III

Study Design.: Retrospective review of the prospectively enrolled, multicenter ASD database. Objective.: We sought to compare clinical and economic outcomes for ASD patients with poor-bone-health versus those with normal-bone-health. Summary of Background Data.: Osteoporosis is a common comorbidity in the adult spinal deformity (ASD) population, with a reported prevalence of 14-29%. Methods.: Patients were categorized into five guideline-concordant cohorts: Confirmed-Osteoporosis (COP: patients with osteopenia or osteoporosis based on DEXA values or a formal preoperative diagnosis); Fracture Osteoporosis (Fx: patients with fragility fractures); Fracture-without-confirmed-Osteoporosis (FXNO: patients with fragility fractures but no osteopenia/osteoporosis diagnosis based on DEXA/formal documentation); Confirmed/fracture-osteoporosis (COP/FX: patients with fragility fractures and/or osteopenia/osteoporosis by DEXA/diagnosis); and the Normal cohort (Nm: patients with normal bone health and no fragility fractures). Cost analyses were performed using multivariate linear regression controlling for BMI, diabetes, baseline deformity (T1PA), and levels fused. Multivariate logistic regression assessed risk of reoperation/complications between groups while controlling for BMI, diabetes, baseline deformity (T1PA), and levels fused. Results.: Overall, 205 patients were included in the Fx-cohort, 136 patients in the COP-cohort, 115 patients in the FXNO-cohort, and 71 patients Nm-cohort. Compared with the Nm-cohort, osteoporotic-cohorts demonstrated significantly worse baseline spinopelvic alignment and higher comorbidity burden. Fx and FXNO cohorts had higher rates of PJF (Fx: 11.2% vs 1.4%, aOR 7.8; FXNO: 10.4% vs 1.4%, aOR 9.0) and revision surgery (Fx: 19.5% vs 7.0%, aOR 2.8; FXNO: 22.6% vs 7.0%, aOR 3.6). Osteoporotic cohorts demonstrated significantly higher short-term QALYs at 6 weeks ( P <0.05) with no difference in the long term. Revision surgery averaged $95,117 per case, translating into an estimated $4.0 million potential-cost-savings. Conclusion.: Our findings highlight the clinical and economic burden of untreated poor bone quality in the setting of ASD surgery. Proactive medical management is crucial to mitigate complications, reduce revisions, and significantly lower healthcare costs in ASD surgery.

Study Design.: Prospective multicenter study Objective.: To determine the incidence of all-cause mortality after adult spinal deformity surgery. Summary of Background Data.: Patients undergoing adult spinal deformity surgery are often frail and the procedures are invasive. The incidence of all-cause mortality among patients undergoing cervical or thoracolumbar deformity surgery is unclear. Methods.: Using 2 prospective, multicenter databases, we identified patients who underwent surgery for cervical deformity surgery from 2013–2020 (n=169) or thoracolumbar deformity from 2008–2020 (n=1507). Mortality incidence density was calculated as follows: 100 × (number of deaths) / (sum of total years of follow-up for all patients). Results.: Of 169 participants in the cervical group (mean±standard deviation age, 61±10 y), death occurred in 19 (11%). The mean time to death was 25±19 months. Mortality incidence density was 4.4 deaths per 100 person-years. The 30-day mortality rate was 0.6% (1/169) and 90-day mortality rate was 1.2% (2/169). The 3 most common causes of death were arrhythmia/cardiac arrest (16%), congestive heart failure (11%), and pneumonia (11%). There were no intraoperative deaths. Of 1507 participants in the thoracolumbar group (mean±standard deviation age, 61±14 y), death occurred in 53 (3.5%). The mean time to death was 32.5±21.5 months. Mean duration of follow-up was 1.8±1.5 years. The mortality incidence density was 0.8 deaths per 100 person-years. The 30-day mortality rate was 0.1% (1/1507) and 90-day mortality rate was 0.3% (4/1507). The 3 most common causes of death were non-spine malignancy (13%), pneumonia (9%), and arrhythmia/cardiac arrest (6%). Conclusions.: The number of deaths per year was higher among cervical deformity patients (4.4 per 100 person-years) than among thoracolumbar deformity patients (0.8 per 100 person-years). Pneumonia and arrhythmia/cardiac arrest were among the most common causes of death in both groups. Level of Evidence.: III

Study Design.: Prospective, multicenter study. Objective.: To compare and characterize complications in adult spinal deformity (ASD) patients with and without three-column osteotomy (3CO). Summary of Background Data.: Although 3CO is associated with increased risk of neurologic adverse events, no study has, to our knowledge, compared and characterized sensory and motor neurologic complications in ASD patients with versus without 3CO. Materials and Methods.: Demographics, surgical characteristics, and neurologic complications were collected for 553 ASD patients. Lower extremity motor scores (LEMSs) were compared at baseline and postoperatively. Multivariate analysis was performed to identify risk factors associated with neurologic adverse events. Results.: Among 553 ASD patients, 130 (23.5%) underwent 3CO. More patients with 3CO were revision patients (67.7% vs . 35.0%; P vs . 31.0%; P =0.008), and had longer operative times (455.6 vs . 407.3 min; P =0.001) and greater estimated blood loss (EBL) (1650 vs . 1000 mL; P versus without 3CO (23.1% vs . 15.4%; P =0.04). Multivariate analysis revealed that older age [odds ratio (OR) 1.288 per 10-year increase, 95% CI: 1.060–1.565, P =0.01] and longer operative time (OR: 1.088, 95% CI: 1.001–1.004, P =0.01) were significant predictors of neurologic adverse events. No between-group difference in LEMS was observed at six-week (49.0 vs . 49.0; P =0.90) or one-year (49.4 vs . 49.3; P =0.71) follow-up. By one-year follow-up, 20.5% of 3CO patients and 21.6% of patients without 3CO had residual motor deficit. Conclusions.: Compared with patients who did not undergo 3CO, more patients with 3CO had prior instrumentation, presented with sagittal deformity, had longer operative time and greater EBL, and were more likely to have a neurologic adverse event. At one-year follow-up, there was no significant difference in LEMS between the two groups. Level of Evidence: Level III.

Objective Lower limbs can play a major compensating role for sagittal malalignment; however, little is known about the different types of compensation. This study aimed to identify different patterns of lower limb compensation and to determine which parameters may affect the recruitment of knee flexion versus hip extension. Methods This study included adult spinal deformity (ASD) patients with full-body X-rays in erect position from a multicentric prospective database. All parameters were measured at baseline: demographics, clinical scores and radiographic parameters: pelvic parameters, pelvic incidence-lumbar lordosis (PI-LL) mismatch, T1 pelvic angle (TPA), sacro-femoral angle (SFA), knee flexion angle (KA), ankle dorsi-flexion angle (AA), pelvic shift (PSh), hip and knee osteoarthritis (OA) grade. A K-means cluster analysis was conducted to identify patterns of lower limb compensation based on SFA and KA. The optimal number of clusters was determined using the silhouette score. The different parameters were then compared across clusters. Results 871 ASD patients were included, of whom 66.9% were females. Mean age was 62.3±14.6 years, mean BMI was 27.7±5.5 kg.m^-2. Four patterns of lower limb compensations were identified: “No compensators”, “Recliners” (mainly hip extension), “Squatters” (mainly knee flexion) and “Mixed compensators” (both).“Mixed” and “Squatters” had significantly larger BMI. The proportion of females was the least in the “Squatters” cluster (47.0%) while it was the highest in the “Recliners” group (79.3%) (p<0.001). The proportion of patients with severe hip OA was the lowest in the “Recliners” (38.5%) while it was the highest in the “Squatters” group (71.9%). Knee OA rate was the highest in the“Squatters” group (72.7%). “Mixed compensators” had the greatest PI-LL mismatch (30.4±20.0°) and “No compensators” the lowest (5.3±21.3°). Pelvic incidence values were the highest in “Recliners” and “Mixed compensators” (59.2±13.1° and 57.0±14.1° respectively). TPA values were the highest in the “Mixed compensators” and the lowest in the “No compensators” (33.3±11.7° versus 16.1±11.5°). The “Squatters” presented the significantly poorest values for disability, frailty, and SRS score. Conclusions Cluster analysis determined four types of lower limb compensation:“Recliners” using only hip extension, “Squatters” using only knee flexion,“Mixed compensators” and “No compensators”. Lower limb compensatory mechanisms recruitment is multifactorial and varies with age, sex, BMI, frailty, knee and hip OA, pelvic incidence, and spinal alignment.

Purpose To determine the viability of preoperative bone health optimization for the prevention of revision surgery due to osteoporosis among adult spinal deformity (ASD) patients using break-even economic modeling. Methods The cost of a DXA scan and total 2-year cost of revision ASD surgery were obtained from institutional records. 2-Year ASD revision rates among patients with osteoporosis were obtained from the literature. An open-access database was used to determine the mean retail price for Teriparatide, Denosumab, and Zoledronic acid. Total optimization costs included the costs of a DXA scan and medication treatment. Costs were adjusted for inflation using the Consumer Price Index to 2023 U.S. dollars. A break-even economic analysis was performed to determine the absolute risk reduction (ARR) and number needed to treat (NNT) to economically justify each treatment. Results DXA scan ($349.28) and revision ASD surgery ($147,731.78) costs were obtained from institutional records. The cost of optimizing patients with DXA and Teriparatide, Denosumab, and Zoledronic acid was $4,410.32, $3,832.78, and $1,552.61, respectively. Each treatment modality was cost-effective at all revision ASD surgery rates. Teriparatide was economically justified if the initial revision rate decreased by 2.99% (NNT = 34), Denosumab by 2.59% (NNT = 39), and Zoledronic acid by 1.05% (NNT = 96). Conclusion Preoperative bone health optimization among ASD patients undergoing surgery is highly cost-effective in the prevention of revision surgery due to osteoporosis. Teriparatide would need to prevent 1 revision surgery out of 34 ASD surgeries, Denosumab 1 out of 39, and Zoledronic acid 1 out of 96 to break-even on costs.

Purpose: To identify factors associated with adjacent-level ossification development (ALOD) after anterior cervical discectomy and fusion (ACDF) and associated clinical outcomes.Methods: We retrospectively reviewed records of 140 adults who underwent primary ACDF for degenerative disc disease. We compared patients with and without ALOD after ACDF. Radiographic measurements and factors associated with ALOD were assessed preoperatively and at minimum 24-month follow-up. Clinical outcomes were incidence of clinical adjacent-segment pathologies (CASP), revision surgery, and patient-reported outcomes.Results: Factors associated with both cranial and caudal ALOD were short plate-to-disc distance (PDD), adjacent-segment kyphosis, hyperlordotic ACDF causing junctional segment kyphosis, and preoperative ossification of the anterior longitudinal ligament (OALL). Mean final adjacent-segment range of motion (ROM) was less in those with cranial ALOD (6.9° ± 2.8°) than in those without cranial ALOD (12° ± 4.2°) (p < 0.01). Mean final adjacent-segment ROM was also less in those with caudal ALOD (5.5° ± 2.4º) than in those without caudal ALOD (8.2º ± 3.7º) (p < 0.01). The incidence of CASP-required surgery was higher in those with caudal ALOD (p = 0.02) but no different in those with cranial ALOD (p = 0.69) compared with those without ALOD.Conclusion: Factors associated with ALOD were a kyphotic segment adjacent to ACDF, hyperlordotic fusion, preoperative OALL, and short PDD. ALOD was associated with less segmental ROM and, for those with caudal but not cranial ALOD, higher incidence of revision surgery for CASP.

Background: Patients with proximal junctional kyphosis (PJK) or failure (PJF) may demonstrate disparate outcomes and recovery when fused to the upper (UT) versus lower (LT) thoracic spine. Few studies have distinguished the reoperation and recovery abilities of patients with PJK or PJF when fused to the upper (UT) versus lower (LT) thoracic spine. Methods: Adult spine deformity patients ≥ 18 yrs with preoperative and 5-year (5Y) data fused to the sacrum/pelvis were included. The rates of PJK, PJK revision, and radiographic PJF were compared between patients with upper instrumented vertebra (UIV) in the upper thoracic spine (UT; T1-T7) and lower thoracic spine (LT; T8-L1). Mean differences were assessed via analyses of covariance, factoring in any differences between cohorts at baseline and any use of PJF prophylaxis. Backstep logistic regressions assessed predictors of achieving Smith et al.’s Best Clinical Outcomes (BCOs) and complications, controlling for similar covariates. Results: A total of 232 ASD patients were included (64.2 ± 10.2 years, 78% female); 36.3% were UT and 63.7% were LT. Postoperatively, the rates of PJK for UT were lower than LT at 1Y (34.6 vs. 50.4%, p = 0.024), 2Y (29.5 vs. 49.6% (p = 0.003), and 5Y (48.7 vs. 62.8%, p = 0.048), with comparable rates of PJF. In total, 4.0% of UT patients underwent subsequent reoperation, compared to 13.0% of LT patients (p = 0.025). A total of 6.0% of patients had recurrent PJK, and 3.9% had recurrent PJF (both p > 0.05). After reoperation, UT patients reported higher rates of improvement in the minimum clinically important difference for ODI by 2Y (p = 0.007) and last follow-up (p < 0.001). While adjusted regression revealed that, for UT patients, the minimization of construct extension was predictive of achieving BCOs by last follow-up (model p < 0.001), no such relationship was identified in LT patients. Conclusions: Patients initially fused to the lower thoracic spine demonstrate an increased incidence of PJK and lower rates of disability improvement, but are at a lessened risk of neurologic complications if reoperation is required.