San Diego Center for Spinal Disorders

Cervical total disc replacement (TDR) is intended to preserve motion and reduce adjacent segment degeneration compared to anterior cervical discectomy and fusion (ACDF). The Simplify Cervical Disc (Globus Medical, Audubon, Pennsylvania), a polyetheretherketone (PEEK)-on-ceramic device with titanium-coated endplates, was approved following encouraging short-term outcomes. However, emerging registries and the Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) reports suggest an increase in device failures and revision surgeries, raising concerns about the device's long-term durability and biological compatibility. We reviewed publicly available FDA MAUDE adverse event reports related to the Simplify disc replacement and the published literature on PEEK-on-ceramic wear mechanisms and titanium coating delamination. Representative clinical cases revised to ACDF procedures were also examined. Device bench testing data from the FDA summary were compared with real-world failure modes. Reported complications were categorized into wear, subsidence, migration, osteolysis, and revision outcomes. Analysis of 96 MAUDE reports revealed diverse complications: osteolysis, device migration, persistent or worsening pain, and intraoperative retrieval difficulties. Histological evaluation of revision specimens demonstrated benign bone and fibrocartilage with foreign material, consistent with PEEK, titanium, and zirconia wear debris, an associated inflammatory reaction, and osteolysis. In vitro data confirm that PEEK-on-ceramic couples generate volumetric wear rates of 0.7-2.1mm³/Mc, with titanium coating delamination further contributing to particulate load. Bench testing demonstrated mechanical adequacy under idealized conditions. However, retrieval findings highlight wear, coating failure, and osteolysis as potential failure pathways in real-world applications. Clinical outcomes after ACDF revision were favorable, suggesting effective salvage treatment. Despite promising early trial results, the Simplify disc demonstrates concerning failure mechanisms, including PEEK wear, titanium coating delamination, and subsequent osteolysis. The discrepancy between bench testing and retrieval analysis underscores the limitations of preclinical simulation in predicting in vivo wear. Vigilant post-market surveillance, independent registry reporting, and further long-term outcome studies are essential. Until durability is confirmed, cautious patient selection and readiness for revision remain critical in clinical practice.

Retrospective cohort study. Identify optimal lumbar lordosis in adult deformity correction to achieve age-adjusted targets and sustained alignment. Surgical adult spinal deformity patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regression analysis was used to identify the relationship between regional curvatures (LL and TK) that enabled achievement of a given global alignment (T1 pelvic angle, TPA) based on pelvic incidence (PI). 347 patients out of 1048 available reached their age-adjusted TPA within 5° (60-year-old, 72% women, body mass index 29 ± 6.2). They had a significant improvement in all sagittal parameters (except PI) from pre-operative baseline to 1year following surgery (P < .001). Multilinear regression predicting L1-S1 based on TK, TPA, and PI demonstrated excellent results (R2 = .85). Simplification of the coefficients of prediction combined with a conversion to an age-based formula led to the following: LL = PI - 0.3TK - 0.5Age + 10. Internal validation of the formula led to a mean error of -.4°, and an absolute error of 5.0°. Internal validation on patients with an age-adjusted alignment revealed similar accuracy across the entire age-adjusted TPA spectrum (ranges of LL errors: ME = .2° to 1.7°, AE = 4.0° to 5.3°). This study provides a simple guideline to identify the amount of LL needed to reach a given alignment (i.e., age-adjusted target) based on PI and associated TK. Implementation of this predictive formula during pre-operative surgical planning may help to reduce unexpected sub-optimal post-operative alignment outcomes.

Study Design:Retrospective cohort study.Objective:To compare the outcomes of patients with adult spinal deformity (ASD)following spinal fusion with the lowest instrumented vertebra (LIV) at L4/L5versus S1/ilium.Methods:A multicenter ASD database was evaluated. Patients were categorized into 2groups based on LIV levels—groups L (fusion to L4/L5) and S (fusion toS1/ilium). Both groups were propensity matched by age and preoperativeradiographic alignments. Patient demographics, operative details,radiographic parameters, revision rates, and health-related quality of life(HRQOL) scores were compared.Results:Overall, 349 patients had complete data, with a mean follow-up of 46 months.Patients in group S (n = 311) were older and had larger sagittal and coronalplane deformities than those in group L (n = 38). After matching, 28patients were allocated to each group with similar demographic,radiographic, and clinical parameters. Sagittal alignment restoration atpostoperative week 6 was significantly better in group S than in group L,but it was similar in both groups at the 2-year follow-up. Fusion toS1/ilium involved a longer operating time, higher PJK rates, and greater PJKangles than that to L4/L5. There were no significant differences in thecomplication and revision rates between the groups. Both groups showedsignificant improvements in HRQOL scores.Conclusions:Fusion to S1/ilium had better sagittal alignment restoration at postoperativeweek 6 and involved higher PJK rates and greater PJK angles than that toL4/L5. The clinical outcomes and rates of revision surgery and complicationswere similar between the groups.

Little information exists regarding longer-term outcomes with minimally invasive spine surgery (MISS), particularly regarding long-segment and deformity procedures. We aimed to evaluate intermediate-term outcomes of MISS for adult spinal deformity (ASD). This retrospective review of a prospectively collected multicenter database examined outcomes at 4 or more years following circumferential MIS (cMIS) or hybrid (HYB) surgery for ASD. A total of 53 patients at 8 academic centers satisfied the following inclusion criteria: age >18years and coronal Cobb > 20°, pelvic incidence-lumbar lordosis (PI-LL) > 10°, or sagittal vertical axis (SVA) > 5cm. Radiographic outcomes demonstrated improvements of PI-LL from 16.8° preoperatively to 10.8° and coronal Cobb angle from 38° preoperatively to 18.2° at 4years. The incidence of complications over the follow-up period was 56.6%. A total of 21 (39.6%) patients underwent reoperation in the thoracolumbar spine, most commonly for adjacent level disease or proximal junctional kyphosis, which occurred in 11 (20.8%) patients. Mean Oswestry Disability Index (ODI) at baseline and years 1 through 4 were 49.9, 33.1, 30.2, 32.7, and 35.0, respectively. The percentage of patients meeting minimal clinically important difference (MCID) (defined as 12% or more from baseline) decreased over time, with leg pain reduction more durable than back pain reduction. Intermediate-term clinical and radiographic improvement following MISS for ASD is sustained, but extent of improvement lessens over time. Outcome variability exists within a subset of patients not meeting MCID, which increases over time after year two. Loss of improvement over time was more notable in back than leg pain. However, average ODI improvement meets MCID at 4years after MIS ASD surgery.

Study Design:Retrospective case series.Objective:Compensatory changes above a proximal junctional kyphosis (PJK) have not been defined. Understanding these mechanisms may help determine optimal level selection when performing revision for PJK. This study investigates how varying PJK location changes proximal spinal alignment.Methods:Patients were grouped by upper instrumented vertebrae (UIV): lower thoracic (LT; T8-L1) or upper thoracic (UT; T1-7). Alignment parameters were compared. Correlation analysis was performed between PJK magnitude and global/cervical alignment.Results:A total of 369 patients were included; mean age of 63 years, body mass index 28, and 81% female, LT (n = 193) versus UT (n = 176). The rate of radiographic PJK was 49%, higher in the LT group (55% vs 42%, P = .01). The UT group displayed significant differences in all cervical radiographic parameters (P < .05) between PJK versus non-PJK patients, while the LT group displayed significant differences in T1S and C2-T3 sagittal vertical axis (SVA) (CTS). In comparing UT versus LT patients, UT had more posterior global alignment (smaller TPA [T1 pelvic angle], SVA, and larger PT [pelvic tilt]) and larger anterior cervical alignment (greater cSVA [cervical SVA], T1S-CL [T1 slope–cervical lordosis] mismatch, CTS) compared to LT. Correlation analysis of PJK magnitude and location demonstrated a correlation with increases in CL, T1S, and CTS in the UT group. In the LT group, PT increased with PJK angle (r = 0.17) and no significant correlations were noted to SVA, cSVA, or T1S-CL.Conclusions:PJK location influences compensation mechanisms of the cervical and thoracic spine. LT PJK results in increased PT and CL with decreased CTS. UT PJK increases CL to counter increases in T1S with continued T1S-CL mismatch and elevated cSVA.

The past decade has seen major advances in techniques for treating more complex spinal disorders using minimally invasive surgery (MIS). While appealing from the standpoint of patient perioperative outcomes, a major impediment to adoption has been the significant learning curve in utilizing MIS techniques. Data were retrospectively analyzed from a multicenter series of adult spinal deformity surgeries treated at eight tertiary spine care centers in the period from 2008 to 2015. All patients had undergone a less invasive or hybrid approach for a deformity correction satisfying the following inclusion criteria at baseline: coronal Cobb angle ≥ 20°, sagittal vertical axis (SVA) > 5 cm, or pelvic tilt > 20°. Analyzed data included baseline demographic details, severity of deformity, surgical metrics, clinical outcomes (numeric rating scale [NRS] score and Oswestry Disability Index [ODI]), radiographic outcomes, and complications. A minimum follow-up of 2 years was required for study inclusion. Across the 8-year study period, among 222 patients, there was a trend toward treating increasingly morbid patients, with the mean age increasing from 50.7 to 62.4 years (p = 0.013) and the BMI increasing from 25.5 to 31.4 kg/m2 (p = 0.12). There was no statistical difference in the severity of coronal and sagittal deformity treated over the study period. With regard to radiographic changes following surgery, there was an increasing emphasis on sagittal correction and, conversely, less coronal correction. There was no statistically significant difference in clinical outcomes over the 8-year period, and meaningful improvements were seen in all years (ODI range of improvement: 15.0-26.9). Neither were there statistically significant differences in major complications; however, minor complications were seen less often as the surgeons gained experience (p = 0.064). Operative time was decreased on average by 47% over the 8-year period.Trends in surgical practice were seen as well. Total fusion construct length was unchanged until the last year when there was a marked decrease in conjunction with a decrease in interbody levels treated (p = 0.004) while obtaining a higher degree of sagittal correction, suggesting more selective but powerful interbody reduction methods as reflected by an increase in the lateral and anterior column resection techniques being utilized. The use of minimally invasive methods for adult spinal deformity surgery has evolved over the past decade. Experienced surgeons are treating older and more morbid patients with similar outcomes. A reliance on selective, more powerful interbody approaches is increasing as well.

This is a retrospective review of prospective multicenter cervical deformity (CD) database. Assess the impact of complication type and Clavien complication (Cc) grade on clinical outcomes of surgical CD patients BACKGROUND:: Validated for general surgery, the Clavien-Dindo complication classification system allows for broad comparison of postoperative complications; however, the applicability of this system is unclear in CD-specific populations. Surgical CD patients above 18 years with baseline and postoperative clinical data were included. Primary outcomes were complication type (renal, infection, cardiac, pulmonary, gastrointestinal, neurological, musculoskeletal, implant-related, radiographic, operative, wound) and Cc grade (I, II, III, IV, V). Secondary outcomes were estimated blood loss (EBL), length of stay (LOS), reoperation, and health-related quality of life (HRQL) score. The univariate analysis assessed the impact of complication type and Cc grade on improvement markers and 1-year postoperative HRQL outcomes. In total, 153 patients (61±10 y, 61% female) underwent surgery for CD (8.1±4.6 levels fused; surgical approach included 48% posterior, 18% anterior, 34% combined). Overall, 63% of patients suffered at least 1 complication. Complication breakdown by type: renal (2.0%), infection (5.2%), cardiac (7.2%), pulmonary (3.9%), gastrointestinal (2.0%), neurological (26.1%), musculoskeletal (0.0%), implant-related (3.9%), radiographic (16.3%), operative (7.8%), and wound (5.2%). Of complication types, only operative complications were associated with increased EBL (P=0.004), whereas renal, cardiac, pulmonary, gastrointestinal, neurological, radiographic, and wound infections were associated with increased LOS (P<0.050). Patients were also assessed by Cc grade: I (28%), II (14.3%), III (16.3%), IV (6.5%), and V (0.7%). Grades I and V were associated with increased EBL (both P<0.050); Cc grade V was the only complication not associated with increased LOS (P=0.610). Increasing complication severity was correlated with increased risk of reoperation (r=0.512; P<0.001), but not inferior 1-year HRQL outcomes (all P>0.05). Increasing complication severity, assessed by the Clavien-Dindo classification system, was not associated with increased EBL, inpatient LOS, or inferior 1-year postoperative HRQL outcomes. Only operative complications were associated with increased EBL. These results suggest a need for modification of the Clavien system to increase applicability and utility in CD-specific populations.

Retrospective review of prospective multicenter database. To investigate the determinants of patient satisfaction with respect to changes in functional limitations 2 years after spinal deformity surgery. For operatively treated adult spine deformity (ASD), patient satisfaction has become an important component of evaluating quality of care. A total of 430 operative patients with ASD with 2-year follow-up were analyzed. Patient satisfaction was assessed using the Scoliosis Research Society 22-item. Latent class analysis was performed to assign individuals to classes based on the changes in pre- and 2-year postoperative functions, assessed using the Oswestry Disability Index (ODI). An ordered logistic regression was conducted to assess the association of class membership and satisfaction. Latent class analysis identified four classes. The worsened-condition class (WC: 1.4%) consisted of patients who were likely to experience worsened function, particularly in lifting and pain intensity. The remained-same class (RS: 13.0%) included patients who remained the same, because the majority reported approximately no change in walking, standing, and sitting. The mild-improved class (mild-I: 40.2%) included patients with mildly enhanced conditions, specifically, in standing, social life, and employment. The most-improved class (most-I: 45.3%) included patients with great improvement after surgery mainly in standing, followed by social life and employment. The odds of being satisfied were significantly increased by 3.91- (P < 0.001) and 16.99-fold (P < 0.001), comparing patients in mild-I and most-I to the RS/WC class, respectively, after controlling for confounders. Improvement in standing, social life, and employment are the most important determinants of patient satisfaction postsurgery. Reduced pain intensity and enhanced walking ability also help to elevate patient satisfaction. However, lifting, personal care, sitting, sleeping, and travelling may be of less importance. Examining the heterogeneity of patient-reported outcome in patients with ASD allows the identification of classes with different patient characteristics and satisfaction, and thus, help to guide tailored provision of care. 4.

Three-column osteotomies (3CO) provide substantial correction for adult spinal deformity (ASD), but carry risks of complications and revisions. The risk-benefit balance of 3CO in the elderly remains unclear. To evaluate sagittal alignment and complications after 3CO in a population over 70-yr old. Radiographic retrospective review of consecutive patients over 70 yr ("Elderly") undergoing 3CO for ASD. Demographic, operative, and outcomes data were collected. Full-spine radiographs were analyzed at baseline and 2-yr postoperatively. Results were compared to a group of young controls ("Young") matched by global sagittal alignment. Elderly (n = 55) and Young (n = 52) were similar in operating room time, blood loss, levels fused, and revision surgeries. Elderly and Young groups had similar baseline radiographic malalignment for pelvic tilt, pelvic incidence-lumbar lordosis (PI-LL), and sagittal vertical axis (P > .5 for all). At 2-yr postoperatively, both groups underwent significant improvement in the setting of sagittal alignment parameters (Elderly: sagittal vertical axis 150 mm to 59 mm, P < .001; pelvic tilt 33° to 25°, P < .001; PI-LL 35° to PI-LL 6°, P < .001). However, the Elderly group underwent significantly greater correction in PI-LL than the Young group (-29° vs -20°, P = .024). There were no differences in total, intraoperative or postoperative complications or revisions between groups, though the Elderly group had more intraoperative complications when major blood loss was included. The Elderly group had more severe proximal junctional kyphosis (22.1° vs 9.6° in Young; P < .001). Compared to young patients, elderly patients may achieve the same, or even better, correction in radiographic spinopelvic parameters. In addition, not only the total intraoperative and postoperative complication rates but also revision rates were comparable between both groups.

OBJECTIVE High-quality studies that compare outcomes of open and minimally invasively placed pedicle screws for adult spinal deformity are needed. Therefore, the authors compared differences in complications from a circumferential minimally invasive spine (MIS) surgery and those from a hybrid surgery. METHODS A retrospective review of a multicenter database of patients with spinal deformity who were treated with an MIS surgery was performed. Database inclusion criteria included an age of ≥ 18 years and at least 1 of the following: a coronal Cobb angle of > 20°, a sagittal vertical axis of > 5 cm, a pelvic incidence-lumbar lordosis angle of > 10°, and/or a pelvic tilt of > 20°. Patients were propensity matched according to the levels instrumented. RESULTS In this database, a complete data set was available for 165 patients, and after those who underwent 3-column osteotomy were excluded, 137 patients were available for analysis; 76 patients remained after propensity matching (MIS surgery group 38 patients, hybrid surgery group 38 patients). The authors found no difference in demographics, number of levels instrumented, or preoperative and postoperative radiographic results. At least 1 complication was suffered by 55.3% of patients in the hybrid surgery group and 44.7% of those in the MIS surgery group (p = 0.359). Patients in the MIS surgery group had significantly fewer neurological, operative, and minor complications than those in the hybrid surgery group. The reoperation rates in both groups were similar. The most common complication category for the MIS surgery group was radiographic and for the hybrid surgery group was neurological. Patients in both groups experienced postoperative improvement in their Oswestry Disability Index and visual analog scale (VAS) back and leg pain scores (all p < 0.05); however, MIS surgery provided a greater reduction in leg pain according to VAS scores. CONCLUSIONS Overall complication rates in the MIS and hybrid surgery groups were similar. MIS surgery resulted in significantly fewer neurological, operative, and minor complications. Reoperation rates in the 2 groups were similar, and despite complications, the patients reported significant improvement in their pain and function.