The Incremental Clinical Benefit of Adding Layers of Complexity to the Planning and Execution of Adult Spinal Deformity Corrective Surgery

BACKGROUND AND OBJECTIVES

For patients with surgical adult spinal deformity (ASD), our understanding of alignment has evolved, especially in the last 20 years. Determination of optimal restoration of alignment and spinal shape has been increasingly studied, yet the assessment of how these alignment schematics have incrementally added benefit to outcomes remains to be evaluated.

METHODS

Patients with ASD with baseline and 2-year were included, classified by 4 alignment measures: Scoliosis Research Society (SRS)-Schwab, Age-Adjusted, Roussouly, and Global Alignment and Proportion (GAP). The incremental benefits of alignment schemas were assessed in chronological order as our understanding of optimal alignment progressed. Alignment was considered improved from baseline based on SRS-Schwab 0 or decrease in severity, Age-Adjusted ideal match, Roussouly current (based on sacral slope) matching theoretical (pelvic incidence-based), and decrease in proportion. Patients separated into 4 first improving in SRS-Schwab at 2-year, second Schwab improvement and matching Age-Adjusted, third two prior with Roussouly, and fourth improvement in all four. Comparison was accomplished with means comparison tests and χ2 analyses.

RESULTS

Sevenhundredthirty-two. patients met inclusion. SRS-Schwab BL: pelvic incidence-lumbar lordosis mismatch (++:32.9%), sagittal vertical axis (++: 23%), pelvic tilt (++:24.6%). 640 (87.4%) met criteria for first, 517 (70.6%) second, 176 (24%) third, and 55 (7.5%) fourth. The addition of Roussouly (third) resulted in lower rates of mechanical complications and proximal junctional kyphosis (48.3%) and higher rates of meeting minimal clinically important difference (MCID) for physical component summary and SRS-Mental (P < .05) compared with the second. Fourth compared with the third had higher rates of MCID for ODI (44.2% vs third: 28.3%, P = .011) and SRS-Appearance (70.6% vs 44.8%, P < .001). Mechanical complications and proximal junctional kyphosis were lower with the addition of Roussouly (P = .024), while the addition of GAP had higher rates of meeting MCID for SRS-22 Appearance (P = .002) and Oswestry Disability Index (P = .085).

CONCLUSION

Our evaluation of the incremental benefit that alignment schemas have provided in ASD corrective surgery suggests that the addition of Roussouly provided the greatest reduction in mechanical complications, while the incorporation of GAP provided the most significant improvement in patient-reported outcomes.

Impact of surgical risk factors for non-union on lumbar spinal fusion outcomes using cellular bone allograft at 24-months follow-up

BACKGROUND

The current report investigates fusion rates and patient-reported outcomes following lumbar spinal surgery using cellular bone allograft (CBA) in patients with risk factors for non-union.

METHODS

A prospective, open label study was conducted in subjects undergoing lumbar spinal fusion with CBA (NCT02969616) to assess fusion success rates and patient-reported outcomes in subjects with risk factors for non-union. Subjects were categorized into low-risk (≤ 1 risk factors) and high-risk (> 1 risk factors) groups. Radiographic fusion status was evaluated by an independent review of dynamic radiographs and CT scans. Patient-reported outcome measures included quality of life (EQ-5D), Oswestry Disability Index (ODI) and Visual Analog Scales (VAS) for back and leg pain. Adverse event reporting was conducted throughout 24-months of follow-up.

RESULTS

A total of 274 subjects were enrolled: 140 subjects (51.1%) were categorized into the high-risk group (> 1 risk factor) and 134 subjects (48.9%) into the low-risk group (≤ 1 risk factors). The overall mean age at screening was 58.8 years (SD 12.5) with a higher distribution of females (63.1%) than males (36.9%). No statistical difference in fusion rates were observed between the low-risk (90.0%) and high-risk (93.9%) groups (p > 0.05). A statistically significant improvement in patient-reported outcomes (EQ-5D, ODI and VAS) was observed at all time points (p < 0.05) in both low and high-risk groups. The low-risk group showed enhanced improvement at multiple timepoints in EQ-5D, ODI, VAS-Back pain and VAS-Leg pain scores compared to the high-risk group (p < 0.05). The number of AEs were similar among risk groups.

CONCLUSIONS

This study demonstrates high fusion rates following lumbar spinal surgery using CBA, regardless of associated risk factors. Patient reported outcomes and fusion rates were not adversely affected by risk factor profiles.

TRIAL REGISTRATION

NCT02969616 (21/11/2016).

Postoperative Discharge to Acute Rehabilitation or Skilled Nursing Facility Compared With Home Does Not Reduce Hospital Readmissions, Return to Surgery, or Improve Outcomes Following Adult Spine Deformity Surgery

STUDY DESIGN

Retrospective review of a prospective multicenter adult spinal deformity (ASD) study.

OBJECTIVE

The aim of this study was to evaluate 30-day readmissions, 90-day return to surgery, postoperative complications, and patient-reported outcomes (PROs) for matched ASD patients receiving nonhome discharge (NON), including acute rehabilitation (REHAB), and skilled nursing facility (SNF), or home (HOME) discharge following ASD surgery.

SUMMARY OF BACKGROUND DATA

Postoperative disposition following ASD surgery frequently involves nonhome discharge. Little data exists for longer term outcomes for ASD patients receiving nonhome discharge versus patients discharged to home.

MATERIALS AND METHODS

Surgically treated ASD patients prospectively enrolled into a multicenter study were assessed for NON or HOME disposition following hospital discharge. NON was further divided into REHAB or SNF. Propensity score matching was used to match for patient age, frailty, spine deformity, levels fused, and osteotomies performed at surgery. Thirty-day hospital readmissions, 90-day return to surgery, postoperative complications, and 1-year and minimum 2-year postoperative PROs were evaluated.

RESULTS

A total of 241 of 374 patients were eligible for the study. NON patients were identified and matched to HOME patients. Following matching, 158 patients remained for evaluation; NON and HOME had similar preoperative age, frailty, spine deformity magnitude, surgery performed, and duration of hospital stay ( P >0.05). Thirty-day readmissions, 90-day return to surgery, and postoperative complications were similar for NON versus HOME and similar for REHAB (N=64) versus SNF (N=42) versus HOME ( P >0.05). At 1-year and minimum 2-year follow-up, HOME demonstrated similar to better PRO scores including Oswestry Disability Index, Short-Form 36v2 questionnaire Mental Component Score and Physical Component Score, and Scoliosis Research Society scores versus NON, REHAB, and SNF ( P <0.05).

CONCLUSIONS

Acute needs must be considered following ASD surgery, however, matched analysis comparing 30-day hospital readmissions, 90-day return to surgery, postoperative complications, and PROs demonstrated minimal benefit for NON, REHAB, or SNF versus HOME at 1- and 2-year follow-up, questioning the risk and cost/benefits of routine use of nonhome discharge.

LEVEL OF EVIDENCE

Level III-prognostic.

Biphasic Calcium Phosphate Bone Graft With a Unique Surface Topography: A Single-Center Ambispective Study for Degenerative Disease of the Lumbar Spine

STUDY DESIGN

This study is an ambispective evaluation and analysis of a single-center cohort.

OBJECTIVE

This study aimed to evaluate the performance of a novel biphasic calcium phosphate (BCP) bone graft with submicron-sized needle-shaped surface topography (BCP<µm) in interbody arthrodesis of the lumbar spine.

METHODS

This study was a single-center ambispective assessment of adult patients receiving BCP<µm as part of their lumbar interbody fusion surgery. The primary outcome was a fusion status on computed tomography (CT) 12 months postoperative. The secondary outcomes included postoperative changes in the visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form 12 (SF-12), and length of stay (LOS).

RESULTS

Sixty-three patients with one- to three-level anterior (48, 76%) and lateral (15, 24%) interbody fusions with posterior instrumentation were analyzed. Thirty-one participants (49%) had three or more comorbidities, including heart disease (43 participants, 68%), obesity (31 participants, 49%), and previous lumbar surgery (23 participants, 37%). The mean ODI decreased by 24. The mean SF-12 physical health and SF-12 mental health improved by a mean of 11.5 and 6.3, respectively. The mean VAS for the left leg, right leg, and back improved by a mean of 25.75, 22.07, and 37.87, respectively. Of 101 levels, 91 (90%) demonstrated complete bridging trabecular bone fusion with no evidence of supplemental fixation failure.

CONCLUSION

The data of BCP<µm in interbody fusions for degenerative disease of the lumbar spine provides evidence of fusion in a complicated cohort of patients.

Predictors of pelvic tilt normalization: a multicenter study on the impact of regional and lower-extremity compensation on pelvic alignment after complex adult spinal deformity surgery

OBJECTIVE

The objective was to determine the degree of regional decompensation to pelvic tilt (PT) normalization after complex adult spinal deformity (ASD) surgery.

METHODS

Operative ASD patients with 1 year of PT measurements were included. Patients with normalized PT at baseline were excluded. Predicted PT was compared to actual PT, tested for change from baseline, and then compared against age-adjusted, Scoliosis Research Society-Schwab, and global alignment and proportion (GAP) scores. Lower-extremity (LE) parameters included the cranial-hip-sacrum angle, cranial-knee-sacrum angle, and cranial-ankle-sacrum angle. LE compensation was set as the 1-year upper tertile compared with intraoperative baseline. Univariate analyses were used to compare normalized and nonnormalized data against alignment outcomes. Multivariable logistic regression analyses were used to develop a model consisting of significant predictors for normalization related to regional compensation.

RESULTS

In total, 156 patients met the inclusion criteria (mean ± SD age 64.6 ± 9.1 years, BMI 27.9 ± 5.6 kg/m2, Charlson Comorbidity Index 1.9 ± 1.6). Patients with normalized PT were more likely to have overcorrected pelvic incidence minus lumbar lordosis and sagittal vertical axis at 6 weeks (p < 0.05). GAP score at 6 weeks was greater for patients with nonnormalized PT (0.6 vs 1.3, p = 0.08). At baseline, 58.5% of patients had compensation in the thoracic and cervical regions. Postoperatively, compensation was maintained by 42% with no change after matching in age-adjusted or GAP score. The patients with nonnormalized PT had increased rates of thoracic and cervical compensation (p < 0.05). Compensation in thoracic kyphosis differed between patients with normalized PT at 6 weeks and those with normalized PT at 1 year (69% vs 35%, p < 0.05). Those who compensated had increased rates of implant complications by 1 year (OR [95% CI] 2.08 [1.32-6.56], p < 0.05). Cervical compensation was maintained at 6 weeks and 1 year (56% vs 43%, p = 0.12), with no difference in implant complications (OR 1.31 [95% CI -2.34 to 1.03], p = 0.09). For the lower extremities at baseline, 61% were compensating. Matching age-adjusted alignment did not eliminate compensation at any joint (all p > 0.05). Patients with nonnormalized PT had higher rates of LE compensation across joints (all p < 0.01). Overall, patients with normalized PT at 1 year had the greatest odds of resolving LE compensation (OR 9.6, p < 0.001). Patients with normalized PT at 1 year had lower rates of implant failure (8.9% vs 19.5%, p < 0.05), rod breakage (1.3% vs 13.8%, p < 0.05), and pseudarthrosis (0% vs 4.6%, p < 0.05) compared with patients with nonnormalized PT. The complication rate was significantly lower for patients with normalized PT at 1 year (56.7% vs 66.1%, p = 0.02), despite comparable health-related quality of life scores.

CONCLUSIONS

Patients with PT normalization had greater rates of resolution in thoracic and LE compensation, leading to lower rates of complications by 1 year. Thus, consideration of both the lower extremities and thoracic regions in surgical planning is vital to preventing adverse outcomes and maintaining pelvic alignment.

Persistent Lower Extremity Compensation for Sagittal Imbalance After Surgical Correction of Complex Adult Spinal Deformity: A Radiographic Analysis of Early Impact

BACKGROUND AND OBJECTIVES

Achieving spinopelvic realignment during adult spinal deformity (ASD) surgery does not always produce ideal outcomes. Little is known whether compensation in lower extremities (LEs) plays a role in this disassociation. The objective is to analyze lower extremity compensation after complex ASD surgery, its effect on outcomes, and whether correction can alleviate these mechanisms.

METHODS

We included patients with complex ASD with 6-week data. LE parameters were as follows: sacrofemoral angle, knee flexion angle, and ankle flexion angle. Each parameter was ranked, and upper tertile was deemed compensation. Patients compensating and not compensating postoperatively were propensity score matched for body mass index, frailty, and T1 pelvic angle. Linear regression assessed correlation between LE parameters and baseline deformity, demographics, and surgical details. Multivariate analysis controlling for baseline deformity and history of total knee/hip arthroplasty evaluated outcomes.

RESULTS

Two hundred and ten patients (age: 61.3 ± 14.1 years, body mass index: 27.4 ± 5.8 kg/m2, Charlson Comorbidity Index: 1.1 ± 1.6, 72% female, 22% previous total joint arthroplasty, 24% osteoporosis, levels fused: 13.1 ± 3.8) were included. At baseline, 59% were compensating in LE: 32% at hips, 39% knees, and 36% ankles. After correction, 61% were compensating at least one joint. Patients undercorrected postoperatively were less likely to relieve LE compensation (odds ratio: 0.2, P = .037). Patients compensating in LE were more often undercorrected in age-adjusted pelvic tilt, pelvic incidence, lumbar lordosis, and T1 pelvic angle and disproportioned in Global Alignment and Proportion (P < .05). Patients matched in sagittal age-adjusted score at 6 weeks but compensating in LE were more likely to develop proximal junctional kyphosis (odds ratio: 4.1, P = .009) and proximal junctional failure (8% vs 0%, P = .035) than those sagittal age-adjusted score-matched and not compensating in LE.

CONCLUSION

Perioperative lower extremity compensation was a product of undercorrecting complex ASD. Even in age-adjusted realignment, compensation was associated with global undercorrection and junctional failure. Consideration of lower extremities during planning is vital to avoid adverse outcomes in perioperative course after complex ASD surgery.

Twenty-four-month interim results from a prospective, single-arm clinical trial evaluating the performance and safety of cellular bone allograft in patients undergoing lumbar spinal fusion

BACKGROUND

Autologous bone grafts are the gold standard for spinal fusion; however, harvesting autologous bone can result in donor site infection, hematomas, increased operative time, and prolonged pain. Cellular bone allografts (CBAs) are a viable alternative that avoids the need for bone harvesting and may increase fusion success alone or when used as an adjunct material. The present study examined the efficacy and safety of CBA when used as an adjunct graft material to lumbar arthrodesis.

METHODS

A prospective, single-arm, multicenter clinical trial (NCT02969616) was conducted in adult subjects (> 18 years of age) undergoing lumbar spinal fusion with CBA graft (CBA used as primary (≥ 50% by volume), with augmentation up to 50%). Radiographic fusion status was assessed by an independent review of dynamic radiographs and CT scans. Clinical outcomes were assessed with the Oswestry Disability Index (ODI), and Visual Analog Scales (VAS) score for back and leg pain. Adverse events were assessed through the 24-month follow-up period. The presented data represents an analysis of available subjects (n = 86) who completed 24 months of postoperative follow-up at the time the data was locked for analysis.

RESULTS

Postoperative 24-month fusion success was achieved in 95.3% of subjects (n = 82/86) undergoing lumbar spinal surgery. Clinical outcomes showed statistically significant improvements in ODI (46.3% improvement), VAS-Back pain (75.5% improvement), and VAS-Leg pain (85.5% improvement) (p < 0.01) scores at Month 24. No subject characteristics or surgical factors were associated with pseudoarthrosis. A favorable safety profile with a limited number of adverse events was observed.

CONCLUSIONS

The use of CBA as an adjunct graft material showed high rates of successful lumbar arthrodesis and significant improvements in pain and disability scores. CBA provides an alternative to autograft with comparable fusion success rates and clinical benefits.

TRIAL REGISTRATION

NCT02969616.

Critical Analysis of Radiographic and Patient Reported Outcomes Following Anterior/Posterior Staged vs. Same Day Surgery in Patients Undergoing Identical Corrective Surgery for Adult Spinal Deformity

STUDYDESIGN

Retrospective cohort study of a prospectively collected multi-center adult spinal deformity (ASD) database.

OBJECTIVE

To compare staged procedures to same-day interventions and identify the optimal time interval between staged surgeries for treatment of ASD.

BACKGROUND

Surgical intervention for ASD is invasive and complex procedure that surgeons often elect to perform on different days (staging). Yet, there remains a paucity of literature on the timing and effects of the interval between stages.

METHODS

ASD patients with two-year (2Y) data undergoing an anterior/posterior (A/P) fusion to the ilium were included. Propensity score matching (PSM) was performed for number of levels fused, number of interbody devices, surgical approaches, number of osteotomies/three-column osteotomy (3CO), frailty, Oswestry Disability Index (ODI), Charlson Comorbidity Index (CCI), revisions, sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), and UIV to create balanced cohorts of Same-Day and Staged surgical patients. Staged patients were stratified by intervening time-period between surgeries, using quartiles.

RESULTS

176 PSM patients were included. Median interval between A/P staged procedures was 3 days. Staged patients had greater operative time and lower ICU stays postop (P<0.05). At 2Y, staged compared to same day showed a greater improvement in T1 slope - cervical lordosis (TS-CL), C2 sacral slope (C2SS), and SRS-Schwab SVA (P<0.05). Staged patients had higher rates of minimal clinically-important difference (MCID) for 1Y SRS-Appearance and 2Y physical component summary (PCS) scores. Assessing different intervals of staging, patients at the 75th percentile interval showed greater improvement in 1Y SRS Pain and Total postop as well as SRS Activity, Pain, Satisfaction, and Total scores (P<0.05) compared to patients in lower quartiles. Compared to the 25th percentile, patients reaching the 50th percentile interval were associated with increased odds of improvement in Global Alignment and Proportion (GAP) score proportionality (9.3[1.6-53.2], P=0.01).

CONCLUSIONS

This investigation is among the first to compare multicenter staged and same day surgery anterior/posterior adult spinal deformity patients fused to ilium using propensity-matching. Staged procedures resulted in significant improvement radiographically, reduced ICU admissions, and superior patient reported outcomes compared to same day procedures. An interval of at least three days between staged procedures is associated with superior outcomes in terms of GAP score proportionality.

Lumbar Discectomy With Bone-Anchored Annular Closure Device in Patients With Large Annular Defects: One-Year Results

BACKGROUND

Reherniation rates following lumbar discectomy are low for most patients; however, patients with a large defect in the annulus fibrosis have a significantly higher risk of recurrence. Previous results from a randomized controlled trial (RCT) demonstrated that the implantation of a bone-anchored annular closure device (ACD) during discectomy surgery lowered the risk of symptomatic reherniation and reoperation over one year with fewer serious adverse events (SAEs) compared to discectomy alone.

OBJECTIVE

The objective of this prospective, post-market, historically controlled study was to evaluate the use of an ACD during discectomy, and to confirm the results of the RCT that was used to establish regulatory approval in the United States.

METHODS

In this post-market study, all patients (N = 55) received discectomy surgery with a bone-anchored ACD. The comparison population was patients enrolled in the RCT study who had discectomy with an ACD (N = 262) or discectomy alone (N = 272). All other eligibility criteria, surgical technique, device characteristics, and follow-up methodology were comparable between studies. Endpoints included rate of symptomatic reherniation or reoperation, SAEs, and patient-reported measures of disability, pain, and quality of life.

RESULTS

Fifty-five patients received ACD implants at 12 sites between May 2020 and February 2021. In the previous RCT, 272 control patients had discectomy surgery alone (RCT-Control), and 262 patients had discectomy surgery with an ACD implant (RCT-ACD). Baseline characteristics across groups were typical of the overall population undergoing lumbar discectomy. The proportion of patients who experienced reherniation and/or reoperation was significantly lower in the ACD group compared to RCT-ACD and RCT-Control groups (p < 0.05). In the ACD study, the one-year rate of symptomatic reherniation was 3.7%, compared to 8.5% in the RCT-ACD group and 17.0% in the RCT-Control group. In the ACD group, the risk of reoperation was 5.5%, compared to 6.5% in the RCT-ACD group and 12.5% in the RCT-Control group. There were no device-related SAEs or device integrity failures in the ACD, and there were clinically meaningful improvements in patient-reported measures of disability, pain, and quality of life.

CONCLUSION

In this post-market study of bone-anchored ACD in patients with large annular defects, rates of symptomatic reherniation, reoperation, and SAEs were all low. Compared to the RCT, the post-market ACD study demonstrated lower rates of reherniation and/or reoperation and measures of back pain one-year post-surgery.

Role of obesity in less radiographic correction and worse health-related quality-of-life outcomes following minimally invasive deformity surgery

OBJECTIVE

Minimally invasive surgery (MIS) for adult spinal deformity (ASD) can offer deformity correction with less tissue manipulation and damage. However, the impact of obesity on clinical outcomes and radiographic correction following MIS for ASD is poorly understood. The goal of this study was to determine the role, if any, that obesity has on radiographic correction and health-related quality-of-life measures in MIS for ASD.

METHODS

Data were collected from a multicenter database of MIS for ASD. This was a retrospective review of a prospectively collected database. Patient inclusion criteria were age ≥ 18 years and coronal Cobb angle ≥ 20°, pelvic incidence-lumbar lordosis mismatch ≥ 10°, or sagittal vertical axis (SVA) > 5 cm. A group of patients with body mass index (BMI) < 30 kg/m2 was the control cohort; BMI ≥ 30 kg/m2 was used to define obesity. Obesity cohorts were categorized into BMI 30-34.99 and BMI ≥ 35. All patients had at least 1 year of follow-up. Preoperative and postoperative health-related quality-of-life measures and radiographic parameters, as well as complications, were compared via statistical analysis.

RESULTS

A total of 106 patients were available for analysis (69 control, 17 in the BMI 30-34.99 group, and 20 in the BMI ≥ 35 group). The average BMI was 25.24 kg/m2 for the control group versus 32.46 kg/m2 (p < 0.001) and 39.5 kg/m2 (p < 0.001) for the obese groups. Preoperatively, the BMI 30-34.99 group had significantly more prior spine surgery (70.6% vs 42%, p = 0.04) and worse preoperative numeric rating scale leg scores (7.71 vs 5.08, p = 0.001). Postoperatively, the BMI 30-34.99 cohort had worse Oswestry Disability Index scores (33.86 vs 23.55, p = 0.028), greater improvement in numeric rating scale leg scores (-4.88 vs -2.71, p = 0.012), and worse SVA (51.34 vs 26.98, p = 0.042) at 1 year postoperatively. Preoperatively, the BMI ≥ 35 cohort had significantly worse frailty (4.5 vs 3.27, p = 0.001), Oswestry Disability Index scores (52.9 vs 44.83, p = 0.017), and T1 pelvic angle (26.82 vs 20.71, p = 0.038). Postoperatively, after controlling for differences in frailty, the BMI ≥ 35 cohort had significantly less improvement in their Scoliosis Research Society-22 outcomes questionnaire scores (0.603 vs 1.05, p = 0.025), higher SVA (64.71 vs 25.33, p = 0.015) and T1 pelvic angle (22.76 vs 15.48, p = 0.029), and less change in maximum Cobb angle (-3.93 vs -10.71, p = 0.034) at 1 year. The BMI 30-34.99 cohort had significantly more infections (11.8% vs 0%, p = 0.004). The BMI ≥ 35 cohort had significantly more implant complications (30% vs 11.8%, p = 0.014) and revision surgery within 90 days (5% vs 1.4%, p = 0.034).

CONCLUSIONS

Obese patients who undergo MIS for ASD have less correction of their deformity, worse quality-of-life outcomes, more implant complications and infections, and an increased rate of revision surgery compared with their nonobese counterparts, although both groups benefit from surgery. Appropriate counseling should be provided to obese patients.

Lumbar Discectomy With Barricaid Device Implantation in Patients at High Risk of Reherniation: Initial Results From a Postmarket Study

Background

Patients with large defects in the annulus fibrosus following lumbar discectomy have high rates of symptomatic reherniation and reoperation. An FDA randomized controlled trial (RCT) with a bone-anchored device (Barricaid, Intrinsic Therapeutics, Woburn, MA) that occludes the annular defect reported significantly lower risk of symptomatic reherniation and reoperation compared to patients receiving discectomy only. However, results of the Barricaid device in real-world use remain limited. 

Methods

This was a post-market study to determine the real-world outcomes of the Barricaid device when used in addition to primary lumbar discectomy in patients with large annular defects. Main outcomes included leg pain severity, Oswestry Disability Index (ODI), adverse events, symptomatic reherniation, and reoperation. Imaging studies were read by an independent imaging core laboratory. This paper reports the initial three-month primary endpoint results from the trial; one-year patient follow-up is ongoing.

Results

Among 55 patients (mean age 41±13 years, 60% male), the mean percent reduction in leg pain severity was 92%, and the mean percent reduction in ODI score was 79%. The three-month rate of symptomatic reherniation was 3.6% and the rate of reoperation was 1.8%. The serious adverse event rate was 5.5%; no device migrations or fractures were observed. 

Conclusion

Among patients with large annular defects following lumbar discectomy treated with the Barricaid device in real-world conditions, early results demonstrated clinically meaningful improvements in patient symptoms and low rates of symptomatic reherniation, reoperation, and complications, which were comparable to those observed with the device in an FDA-regulated trial.

Cervical Total Disc Replacement: Indications and Technique

Cervical total disc replacement devices have been marketed in the United States (US) since 2007, with abundant level 1 evidence published on the treatment. Adherence to the strict inclusion/exclusion criteria and the surgical technique training of the US clinical trials remains the consistent and conservative approach to patient selection and implantation technique. However, patient selection and surgical technique remain debated among US surgeons as the published data and available cervical total disc replacements continue to grow.

Ten-Year Outcomes of 1- and 2-Level Cervical Disc Arthroplasty From the Mobi-C Investigational Device Exemption Clinical Trial

BACKGROUND

Short- and mid-term studies have shown the effectiveness of cervical disc arthroplasty (CDA) to treat cervical disc degeneration.

OBJECTIVE

To report the 10-yr outcomes of a multicenter experience with cervical arthroplasty for 1- and 2-level pathology.

METHODS

This was a prospective study of patients treated with CDA at 1 or 2 contiguous levels using the Mobi-C® Cervical Disc (Zimmer Biomet). Following completion of the 7-yr Food and Drug Administration postapproval study, follow-up continued to 10 yr for consenting patients at 9 high-enrolling centers. Clinical and radiographic endpoints were collected out to 10 yr.

RESULTS

At 10 yr, patients continued to have significant improvement over baseline Neck Disability Index (NDI), neck and arm pain, neurologic function, and segmental range of motion (ROM). NDI and pain outcomes at 10 yr were significantly improved from 7 yr. Segmental and global ROM and sagittal alignment also were maintained from 7 to 10 yr. Clinically relevant adjacent segment pathology was not significantly different between 7 and 10 yr. The incidence of motion restricting heterotopic ossification at 10 yr was not significantly different from 7 yr for 1-level (30.7% vs 29.6%) or 2-level (41.7% vs 39.2%) patients. Only 2 subsequent surgeries were reported after 7 yr.

CONCLUSION

Our results through 10 yr were comparable to 7-yr outcomes, demonstrating that CDA with Mobi-C continues to be a safe and effective surgical treatment for patients with 1- or 2-level cervical degenerative disc disease.

Patient-related and radiographic predictors of inferior health-related quality-of-life measures in adult patients with nonoperative spinal deformity

OBJECTIVE

Patients with nonoperative (N-Op) adult spinal deformity (ASD) have inferior long-term spinopelvic alignment and clinical outcomes. Predictors of lower quality-of-life measures in N-Op populations have yet to be sufficiently investigated. The aim of this study was to identify patient-related factors and radiographic parameters associated with inferior health-related quality-of-life (HRQOL) scores in N-Op ASD patients.

METHODS

N-Op ASD patients with complete radiographic and outcome data at baseline and 2 years were included. N-Op patients and operative (Op) patients were propensity score matched for baseline disability and deformity. Patient-related factors and radiographic alignment parameters (pelvic tilt [PT], sagittal vertical axis [SVA], pelvic incidence [PI]-lumbar lordosis [LL] mismatch, mismatch between cervical lordosis and T1 segment slope [TS-CL], cervical-thoracic pelvic angle [PA], and others) at baseline and 2 years were analyzed as predictors for moderate to severe 2-year Oswestry Disability Index (ODI > 20) and failing to meet the minimal clinically importance difference (MCID) for 2-year Scoliosis Research Society Outcomes Questionnaire (SRS) scores (< 0.4 increase from baseline). Conditional inference decision trees identified predictors of each HRQOL measure and established cutoffs at which factors have a global effect. Random forest analysis (RFA) generated 5000 conditional inference trees to compute a variable importance table for top predictors of inferior HRQOL. Statistical significance was set at p < 0.05.

RESULTS

Six hundred sixty-two patients with ASD (331 Op patients and 331 N-Op patients) with complete radiographic and HRQOL data at their 2-year follow-up were included. There were no differences in demographics, ODI, and Schwab deformity modifiers between groups at baseline (all p > 0.05). N-Op patients had higher 2-year ODI scores (27.9 vs 20.3, p < 0.001), higher rates of moderate to severe disability (29.3% vs 22.4%, p = 0.05), lower SRS total scores (3.47 vs 3.91, p < 0.001), and higher rates of failure to reach SRS MCID (35.3% vs 15.7%, p < 0.001) than Op patients at 2 years. RFA ranked the top overall predictors for moderate to severe ODI at 2 years for N-Op patients as follows: 1) frailty index > 2.8, 2) BMI > 35 kg/m2, T4PA > 28°, and 4) Charlson Comorbidity Index > 1. Top radiographic predictors were T4PA > 28° and C2-S1 SVA > 93 mm. RFA also ranked the top overall predictors for failure to reach 2-year SRS MCID for N-Op patients, as follows: 1) T12-S1 lordosis > 53°, 2) cervical SVA (cSVA) > 28 mm, 3) C2-S1 angle > 14.5°, 4) TS-CL > 12°, and 5) PT > 23°. The top radiographic predictors were T12-S1 Cobb angle, cSVA, C2-S1 angle, and TS-CL.

CONCLUSIONS

When controlling for baseline deformity in N-Op versus Op patients, subsequent deterioration in frailty, BMI, and radiographic progression over a 2-year follow-up were found to drive suboptimal patient-reported outcome measures in N-Op cohorts as measured by validated ODI and SRS clinical instruments.

Factors influencing upper-most instrumented vertebrae selection in adult spinal deformity patients: qualitative case-based survey of deformity surgeons

Background

The decision upper-most instrumented vertebrae (UIV) in a multi-level fusion procedure can dramatically influence outcomes of corrective spine surgery. We aimed to create an algorithm for selection of UIV based on surgeon selection/reasoning of sample cases.

Methods

The clinical/imaging data for 11 adult spinal deformity (ASD) patients were presented to 14 spine deformity surgeons who selected the UIV and provided reasons for avoidance of adjacent levels. The UIV chosen was grouped into either upper thoracic (UT, T1-T6), lower thoracic (LT, T7-T12), lumbar or cervical. Disagreement between surgeons was defined as ≥3 not agreeing. We performed a descriptive analysis of responses and created an algorithm for choosing UIV then applied this to a large database of ASD patients.

Results

Surgeons agreed in 8/11 cases on regional choice of UIV. T10 was the most common UIV in the LT region (58%) and T3 was the most common UIV in the UT region (44%). The most common determinant of UIV in the UT region was proximal thoracic kyphosis and presence of coronal deformity. The most common determinant of UIV in the LT region was small proximal thoracic kyphosis. Within the ASD database (236 patients), when the algorithm called for UT fusion, patients fused to TL region were more likely to develop proximal junctional kyphosis (PJK) at 1 year post-operatively (76.9% vs. 38.9%, P=0.025).

Conclusions

Our algorithm for selection of UIV emphasizes the role of proximal and regional thoracic kyphosis. Failure to follow this consensus for UT fusion was associated with twice the rate of PJK.

Revision Surgery Rates After Minimally Invasive Adult Spinal Deformity Surgery: Correlation with Roussouly Spine Type at 2-Year Follow-Up?

BACKGROUND

Spinopelvic parameters have hitherto dictated much of adult spinal deformity (ASD) correction. The Roussouly classification is used for the normal adult spine. We evaluated whether a correlation would be found between the Roussouly type and the rate of revision surgery in patients with ASD undergoing circumferential minimally invasive spinal (cMIS) correction.

METHODS

A multicenter retrospective review of patients who had undergone cMIS surgery for ASD was performed. The inclusion criteria were age ≥18 years and 1 of the following: coronal Cobb angle >20°, sagittal vertical axis >5 cm, pelvic tilt >20°, pelvic incidence (PI) to lumbar lordosis (LL) mismatch >10°, cMIS surgery, and a minimum of 2 years of follow-up data available. The patients were classified by Roussouly type, and the clinical and radiographic outcomes were evaluated.

RESULTS

A total of 104 patients were included in the present analysis. Of the 104 patients, 41 had Roussouly type 1, 32 had type 2, 23 had type 3, and 8 had type 4. Preoperatively, the patients with type 4 had the highest PI (P = 0.002) and LL (P < 0.001). Postoperatively, the PI-LL mismatch, Cobb angle, and sagittal vertical axis were not different among the 4 groups. However, the patients with type 2 had had the highest rate of complications (type 1, 29.3%; type 2, 61.3%; type 3, 34.8%; type 4, 25.0%; P = 0.031). The reoperation rates were comparable (type 1, 19.5%; type 2, 38.7%; type 3, 13.0%; type 4, 12.5%; P = 0.097). The reoperation rates for adjacent segment degeneration or proximal junctional kyphosis were also comparable (P = 0.204 and P = 0.060, respectively).

CONCLUSIONS

We did not find a clear correlation between Roussouly type and the rate of revision surgery for adjacent segment disease or proximal junctional kyphosis in patients who had undergone cMIS surgery for ASD.

PEEK versus titanium cages in lateral lumbar interbody fusion: a comparative analysis of subsidence

OBJECTIVE

The authors have provided a review of radiographic subsidence after lateral lumbar interbody fusion (LLIF) as a comparative analysis between titanium and polyetheretherketone (PEEK) cages. Many authors describe a reluctance to use titanium cages in spinal fusion secondary to subsidence concerns due to the increased modulus of elasticity of metal cages. The authors intend for this report to provide observational data regarding the juxtaposition of these two materials in the LLIF domain.

METHODS

A retrospective review of a prospectively maintained database identified 113 consecutive patients undergoing lateral fusion for degenerative indications from January to December 2017. The surgeons performing the cage implantations were two orthopedic spine surgeons and two neurosurgeons. Plain standing radiographs were obtained at 1–2 weeks, 8–12 weeks, and 12 months postoperatively. Using a validated grading system, interbody subsidence into the endplates was graded at these time points on a scale of 0 to III. The primary outcome measure was subsidence between the two groups. Secondary outcomes were analyzed as well.

RESULTS

Of the 113 patients in the sample, groups receiving PEEK and titanium implants were closely matched at 57 and 56 patients, respectively. Cumulatively, 156 cages were inserted and recombinant human bone morphogenetic protein–2 (rhBMP-2) was used in 38.1%. The average patient age was 60.4 years and average follow-up was 75.1 weeks. Subsidence in the titanium group in this study was less common than in the PEEK cage group. At early follow-up, groups had similar subsidence outcomes. Statistical significance was reached at the 8- to 12-week and 52-week follow-ups, demonstrating more subsidence in the PEEK cage group than the titanium cage group. rhBMP-2 usage was also highly correlated with higher subsidence rates at all 3 follow-up time points. Age was correlated with higher subsidence rates in univariate and multivariate analysis.

CONCLUSIONS

Titanium cages were associated with lower subsidence rates than PEEK cages in this investigation. Usage of rhBMP-2 was also robustly associated with higher endplate subsidence. Each additional year of age correlated with an increased subsidence risk. Subsidence in LLIF is likely a response to a myriad of factors that include but are certainly not limited to cage material. Hence, the avoidance of titanium interbody implants secondary solely to concerns over a modulus of elasticity likely overlooks other variables of equal or greater importance.

Patient Selection in Cervical Disc Arthroplasty

BACKGROUND

Patient selection for cervical disc arthroplasty (CDA) in the United States remains a topic of debate among surgeons. Many surgeons base US patient selection for CDA implantation on the Food and Drug Administration (FDA) indications/contraindications. While off-label use does occur, the frequency and extent of off-label use in the US remains largely unknown. Outside the United States, patient selection is notably less stringent; however such data also remain largely unpublished or presented/published with a low level of evidence. Here, we will review the current approved US on-label patient selection criteria for CDA and discuss the rationale and supporting evidence to expand these criteria in the United States.

METHODS

A PubMed literature search was completed using the keywords "cervical disc arthroplasty" and "cervical disc replacement." The articles were evaluated by the authors for patient selection criteria.

CONCLUSIONS

The current published data do not conclusively prove that the patients excluded from CDA by strict adherence to FDA indications would benefit from CDA surgery over anterior cervical discectomy and fusion. As surgeons, it is a difficult decision regarding when to expand indications to include off-label use of CDA. In our practice, generally CDA patient selection agrees with the FDA indications and contraindications, as there is a lack of level 1 evidence to confirm effectiveness of CDA outside of the current FDA indications. We will likely need more well-constructed studies to include prospective and controlled trials that specifically evaluate the "off-label" applications before US surgeons are convinced to expand indications and insurance companies agree to reimburse.

Intermediate-term clinical and radiographic outcomes with less invasive adult spinal deformity surgery: patients with a minimum follow-up of 4 years

BACKGROUND

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).

METHODS

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 > 18 years and coronal Cobb > 20°, pelvic incidence-lumbar lordosis (PI-LL) > 10°, or sagittal vertical axis (SVA) > 5 cm.

RESULTS

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 4 years. 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.

CONCLUSIONS

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 4 years after MIS ASD surgery.

Minimally Invasive Spinal Deformity Surgery: Analysis of Patients Who Fail to Reach Minimal Clinically Important Difference

BACKGROUND

It is well known that clinical improvements following surgical intervention are variable. While all surgeons strive to maximize reliability and degree of improvement, certain patients will fail to achieve meaningful gains. We aim to analyze patients who failed to reach minimal clinically important difference (MCID) in an effort to improve outcomes for minimally invasive deformity surgery.

METHODS

Data were collected on a multicenter registry of minimally invasive surgery adult spinal deformity surgeries. Patient inclusion criteria were age ≥18 years, coronal Cobb ≥20 degrees, pelvic incidence-lumbar lordosis ≥10 degrees, or a sagittal vertical axis >5 cm. All patients had minimum 2 years' follow-up (N = 222). MCID was defined as 12.8 or more points of improvement in the Oswestry Disability Index. Up to 2 different etiologies for failure were allowed per patient.

RESULTS

We identified 78 cases (35%) where the patient failed to achieve MCID at long-term follow-up. A total of 82 identifiable causes were seen in these patients with 14 patients having multiple causes. In 6 patients, the etiology was unclear. The causes were subclassified as neurologic, medical, structural, under treatment, degenerative progression, traumatic, idiopathic, and floor effects. In 71% of cases, an identifiable cause was related to the spine, whereas in 35% the cause was not related to the spine.

CONCLUSIONS

Definable causes of failed MIS ASD surgery are often identifiable and similar to open surgery. In some cases the cause is treatable and structural. However, it is also common to see failure due to pathologies unrelated to the index surgery.

Fatty infiltration of the cervical extensor musculature, cervical sagittal balance, and clinical outcomes: An analysis of operative adult cervical deformity patients

PURPOSE

To assess preliminary associations between fatty-infiltration (FI) of cervical spine extensor musculature, cervical sagittal balance, and clinical outcomes in cervical deformity (CD) patients.

METHODS

Operative CD patients (C2-C7 Cobb > 10°, CL > 10°, cSVA > 4 cm, or CBVA > 25°) with pre-operative (BL) MRIs and 1-year (1Y) post-operative MRIs or CTs were assessed for fatty-infiltration of cervical extensor musculature, using dedicated imaging software at each C2-C7 intervertebral level and the apex of deformity (apex). FI was gauged as a ratio of fat-free-muscle-cross-sectional-area (FCSA) over total-muscle-CSA (TCSA), with lower ratio values indicating greater FI. BL-1Y associations between FI, sagittal alignment, and clinical outcomes were assessed using appropriate parametric and non-parametric tests.

RESULTS

22 patients were included (Age 59.22, 71.4%F, BMI 29.2, CCI:0.75, Frailty: 0.43). BL deformity presentation: TS-CL: 29.0°, C2-C7 Sagittal Cobb:-1.6°, cSVA:30.4 mm. No correlations were observed between BL fatty-infiltration, sagittal alignment, frailty, or clinical outcomes (p > 0.05). Following surgical correction, C2-C7 (BL: 0.59 vs 1Y:0.67, p = 0.005) and apex (BL: 0.59 vs. 1Y: 0.66, p = 0.33) fatty-infiltration decreased. Achievement of lordotic curvature correlated with C2-C7 fatty infiltration reduction (R_s: 0.495, p < 0.05), and patients with residual postoperative TS-CL and cSVA malalignment were associated with greater apex fatty-infiltration (R_s: -0.565, -0.561; p < 0.05). C2-C7 FI improvement was associated with NRS back pain reduction (R_s: -0.630, p < 0.05), and greater apex fatty-infiltration at BL was associated with minor perioperative complication occurrence (R_s: 0.551, p = 0.014).

CONCLUSIONS

Deformity correction and sagittal balance appear to influence the reestablishment of cervical muscle tone from C2-C7 and reduction of back pain for severely frail CD patients. This analysis helps to understand cervical extensor musculature's role amongst CD patients.

Minimally Invasive Surgery for Mild-to-Moderate Adult Spinal Deformities: Impact on Intensive Care Unit and Hospital Stay

OBJECTIVE

To compare circumferential minimally invasive (cMIS) versus open surgeries for mild-to-moderate adult spinal deformity (ASD) with regard to intensive care unit (ICU) and hospital lengths of stay (LOS).

METHODS

A retrospective review of 2 multicenter ASD databases with 426 ASD (sagittal vertical axis <6 cm) surgery patients with 4 or more fusion levels and 2-year follow-up was conducted. ICU stay, LOS, and estimated blood loss (EBL) were compared between open and cMIS surgeries.

RESULTS

Propensity matching resulted in 88 patients (44 cMIS, 44 open). cMIS were older (61 vs. 53 years, P = 0.005). Mean levels fused were 6.5 in cMIS and 7.1 in open (P = 0.368). Preoperative lordosis was higher in open than in cMIS (42.7° vs. 40.9°, P = 0.016), and preoperative visual analog score back pain was greater in open than in cMIS (7 vs. 6.2, P = 0.033). Preoperative and postoperative spinopelvic parameters and coronal Cobb angles were not different. EBL was 534 cc in cMIS and 1211 cc in open (P < 0.001). Transfusions were less in cMIS (27.3% vs. 70.5%, P < 0.001). ICU stay was 0.6 days for cMIS and 1.2 days for open (P = 0.009). Hospital LOS was 7.9 days for cMIS versus 9.6 for open (P = 0.804).

CONCLUSIONS

For patients with mild-to-moderate ASD, cMIS surgery had a significantly lower EBL and shorter ICU stay. Major and minor complication rates were lower in cMIS patients than open patients. Overall LOS was shorter in cMIS patients, but did not reach statistical significance.

Early and Late Reoperation Rates With Various MIS Techniques for Adult Spinal Deformity Correction

STUDY DESIGN

A multicenter retrospective review of an adult spinal deformity database.

OBJECTIVE

We aimed to characterize reoperation rates and etiologies of adult spinal deformity surgery with circumferential minimally invasive surgery (cMIS) and hybrid (HYB) techniques.

METHODS

Inclusion criteria were age ≥18 years, and one of the following: coronal Cobb >20°, sagittal vertical axis >5 cm, pelvic tilt >20°, and pelvic incidence-lumbar lordosis >10°. Patients with either cMIS or HYB surgery, ≥3 spinal levels treated with 2-year minimum follow-up were included.

RESULTS

A total of 133 patients met inclusion for this study (65 HYB and 68 cMIS). Junctional failure (13.8%) was the most common reason for reoperation in the HYB group, while fixation failure was the most common reason in the cMIS group (14.7%). There was a higher incidence of proximal junctional failure (PJF) than distal junctional failure (DJF) within HYB (12.3% vs 3.1%), but no significant differences in PJF or DJF rates when compared to cMIS. Early (<30 days) reoperations were less common (cMIS = 1.5%; HYB = 6.1%) than late (>30 days) reoperations (cMIS = 26.5%; HYB = 27.7%), but early reoperations were more common in the HYB group after propensity matching, largely due to infection rates (10.8% vs 0%, P = .04).

CONCLUSIONS

Adult spinal deformity correction with cMIS and HYB techniques result in overall reoperation rates of 27.9% and 33.8%, respectively, at minimum 2-year follow-up. Junctional failures are more common after HYB approaches, while pseudarthrosis/fixation failures happen more often with cMIS techniques. Early reoperations were less common than later returns to the operating room in both groups, but cMIS demonstrated less risk of infection and early reoperation when compared with the HYB group.

Treatment of the Fractional Curve of Adult Scoliosis With Circumferential Minimally Invasive Surgery Versus Traditional, Open Surgery: An Analysis of Surgical Outcomes

STUDY DESIGN

Retrospective, multicenter review of adult scoliosis patients with minimum 2-year follow-up.

OBJECTIVE

Because the fractional curve (FC) of adult scoliosis can cause radiculopathy, we evaluated patients treated with either circumferential minimally invasive surgery (cMIS) or open surgery.

METHODS

A multicenter retrospective adult deformity review was performed. Patients included: age >18 years with FC >10°, ≥3 levels of instrumentation, 2-year follow-up, and one of the following: coronal Cobb angle (CCA) > 20°, pelvic incidence and lumbar lordosis (PI-LL) > 10°, pelvic tilt (PT) > 20°, and sagittal vertical axis (SVA) > 5 cm.

RESULTS

The FC was treated in 118 patients, 79 open and 39 cMIS. The FCs had similar coronal Cobb angles preoperative (17° cMIS, 19.6° open) and postoperative (7° cMIS, 8.1° open), but open had more levels treated (12.1 vs 5.7). cMIS patients had greater reduction in VAS leg (6.4 to 1.8) than open (4.3 to 2.5). With propensity matching 40 patients for levels treated (cMIS: 6.6 levels, N = 20; open: 7.3 levels, N = 20), both groups had similar FC correction (18° in both preoperative, 6.9° in cMIS and 8.5° postoperative). Open had more posterior decompressions (80% vs 22.2%, P < .001). Both groups had similar preoperative (Visual Analogue Scale [VAS] leg 6.1 cMIS and 5.4 open) and postoperative (VAS leg 1.6 cMIS and 3.1 open) leg pain. All cMIS patients had interbody grafts; 35% of open did. There was no difference in change of primary CCA, PI-LL, LL, Oswestry Disability Index, or VAS Back.

CONCLUSION

Patients' FCs treated with cMIS had comparable reduction of leg pain compared with those treated with open surgery, despite significantly fewer cMIS patients undergoing direct decompression.

Patients with High Pelvic Tilt Achieve the Same Clinical Success as Those with Low Pelvic Tilt After Minimally Invasive Adult Deformity Surgery

BACKGROUND

Pelvic tilt (PT) is a compensatory mechanism for adult spinal deformity patients to mitigate sagittal imbalance. The association between preop PT and postop clinical and radiographic outcomes has not been well studied in patients undergoing minimally invasive adult deformity surgery.

OBJECTIVE

To evaluate clinical and radiographic outcomes in adult spinal deformity patients with high and low preoperative PT treated surgically using less invasive techniques.

METHODS

Retrospective case-control, institutional review board-approved study. A multicenter, minimally invasive surgery spinal deformity patient database was queried for 2-yr follow-up with complete radiographic and health-related quality of life (HRQOL) data. Hybrid surgery patients were excluded. Inclusion criteria were as follows: age > 18 and either coronal Cobb angle > 20, sagittal vertical axis > 5 cm, pelvic incidence-lumbar lordosis (PI-LL) > 10 or PT > 20. Patients were stratified by preop PT as per Schwab classification: low (PT< 20), mid (PT 20-30), or high (>30). Postoperative radiographic alignment parameters (PT, PI, LL, Cobb angle, sagittal vertical axis) and HRQOL data (Visual Analog Scale Back/Leg, Oswestry Disability Index) were evaluated and analyzed.

RESULTS

One hundred sixty-five patients had complete 2-yr outcomes data, and 64 patients met inclusion criteria (25 low, 21 mid, 18 high PT). High PT group had higher preop PI-LL mismatch (32.1 vs 4.7; P < .001). At last follow-up, 76.5% of patients in the high PT group had continued PI-LL mismatch compared to 34.8% in the low PT group (P < .006). There was a difference between groups in terms of postop changes of PT (-3.9 vs 1.9), LL (8.7 vs 0.5), and PI-LL (-9.5 vs 0.1). Postoperatively, HRQOL data (Oswestry Disability Index and Visual Analog Scale) were significantly improved in both groups (P < .001).

CONCLUSION

Adult deformity patients with high preoperative PT treated with minimally invasive surgical techniques had less radiographic success but equivalent clinical outcomes as patients with low PT.

Cost Utility Analysis of the Cervical Artificial Disc vs Fusion for the Treatment of 2-Level Symptomatic Degenerative Disc Disease: 5-Year Follow-up

Supplemental Digital Content is Available in the Text.

BACKGROUND:

The cervical total disc replacement (cTDR) was developed to treat cervical degenerative disc disease while preserving motion.

OBJECTIVE:

Cost-effectiveness of this intervention was established by looking at 2-year follow-up, and this update reevaluates our analysis over 5 years.

METHODS:

Data were derived from a randomized trial of 330 patients. Data from the 12-Item Short Form Health Survey were transformed into utilities by using the SF-6D algorithm. Costs were calculated by extracting diagnosis-related group codes and then applying 2014 Medicare reimbursement rates. A Markov model evaluated quality-adjusted life years (QALYs) for both treatment groups. Univariate and multivariate sensitivity analyses were conducted to test the stability of the model. The model adopted both societal and health system perspectives and applied a 3% annual discount rate.

RESULTS:

The cTDR costs $1687 more than anterior cervical discectomy and fusion (ACDF) over 5 years. In contrast, cTDR had $34 377 less productivity loss compared with ACDF. There was a significant difference in the return-to-work rate (81.6% compared with 65.4% for cTDR and ACDF, respectively; P = .029). From a societal perspective, the incremental cost-effective ratio (ICER) for cTDR was −$165 103 per QALY. From a health system perspective, the ICER for cTDR was $8518 per QALY. In the sensitivity analysis, the ICER for cTDR remained below the US willingness-to-pay threshold of $50 000 per QALY in all scenarios (−$225 816 per QALY to $22 071 per QALY).

CONCLUSION:

This study is the first to report the comparative cost-effectiveness of cTDR vs ACDF for 2-level degenerative disc disease at 5 years. The authors conclude that, because of the negative ICER, cTDR is the dominant modality.

ABBREVIATIONS:

ACDF, anterior cervical discectomy and fusion

AWP, average wholesale price

CE, cost-effectiveness

CEA, cost-effectiveness analysis

CPT, Current Procedural Terminology

cTDR, cervical total disc replacement

CUA, cost-utility analysis

DDD, degenerative disc disease

DRG, diagnosis-related group

FDA, US Food and Drug Administration

ICER, incremental cost-effectiveness ratio

IDE, Investigational Device Exemption

NDI, neck disability index

QALY, quality-adjusted life years

RCT, randomized controlled trial

RTW, return-to-work

SF-12, 12-Item Short Form Health Survey

VAS, visual analog scale

WTP, willingness-to-pay

A Critical Analysis of Sagittal Plane Deformity Correction With Minimally Invasive Adult Spinal Deformity Surgery: A 2-Year Follow-Up Study

INTRODUCTION

Sagittal plane realignment is important to achieve desirable clinical outcomes after adult spinal deformity (ASD) surgery. This study evaluates the impact of minimally invasive (MIS) techniques on sagittal plane alignment and clinical outcomes in ASD patients.

METHODS

A retrospective, multi-center review of ASD patients (age ≥18 years, and with one of the following: coronal Cobb ≥20°, sagittal vertical axis [SVA] >5 cm, and/or pelvic tilt >25°), MIS surgery, and four or more levels instrumented. Patients were stratified by baseline SRS-Schwab global alignment modifier (GAM) into three groups: 0 (SVA <4 cm), + (SVA 4-9.5 cm), or ++ (SVA >9.5 cm). Radiographic and clinical outcomes measures were analyzed with a minimum of 2-year follow-up.

RESULTS

A total of 96 ASD patients were identified, and 63 met the study's inclusion criteria of circumferential MIS or posterior MIS only, with four or more levels instrumented (n: Group 0 = 37, Group + = 15, and Group ++ = 11). Group 0 was younger than ++ (56.8 vs. 69.6 years), with a higher proportion of females than Group + or ++ (83.8% vs. 66.7% and 54.5%, respectively). Baseline HRQoL was similar. Postoperatively, Groups 0 and + had improved Oswestry Disability Index (ODI) and numeric rating scale (NRS) back and leg scores. Group ++ only had improvement in NRS scores. At the latest follow-up, Groups 0 and ++ had similar sagittal measurements except for PT (21.6 vs. 23.6, p = .009). The + group had improvement in PI-LL (24.2 to 17; p = .015) and LL (30.9 to 38.3; p = .013). Eight of 27 (21.6%) Group 0 patients deteriorated (4 to Group +, 4 to Group ++). Three of 15 (20.0%) Group + patients deteriorated to Group ++, and 3 improved to Group 0. Six of 11 (54.5%) Group ++ patients improved (3 to Group + and 3 to Group 0).

CONCLUSIONS

MIS techniques successfully stabilized ASD patients with Group 0 and + deformities and improved HRQoL. This study suggests that severe sagittal imbalance is not adequately treated with MIS approaches.

Does MIS Surgery Allow for Shorter Constructs in the Surgical Treatment of Adult Spinal Deformity?

BACKGROUND: The length of construct can potentially influence perioperative risks in adult spinal deformity (ASD) surgery. A head-to-head comparison between open and minimally invasive surgery (MIS) techniques for treatment of ASD has yet to be performed.

OBJECTIVE: To examine the impact of MIS approaches on construct length and clinical outcomes in comparison to traditional open approaches when treating similar ASD profiles.

METHODS: Two multicenter databases for ASD, 1 involving MIS procedures and the other open procedures, were propensity matched for clinical and radiographic parameters in this observational study. Inclusion criteria were ASD and minimum 2-year follow-up. Independent t-test and chi-square test were used to evaluate and compare outcomes.

RESULTS: A total of 1215 patients were identified, with 84 patients matched in each group. Statistical significance was found for mean levels fused (4.8 for circumferential MIS [cMIS] and 10.1 for open), mean interbody fusion levels (3.6 cMIS and 2.4 open), blood loss (estimated blood loss 488 mL cMIS and 1762 mL open), and hospital length of stay (6.7 days cMIS and 9.7 days open). There was no significant difference in preoperative radiographic parameters or postoperative clinical outcomes (Owestry Disability Index and visual analog scale) between groups. There was a significant difference in postoperative lumbar lordosis (43.3° cMIS and 49.8° open) and pelvic incidence-lumbar lordosis correction (10.6° cMIS and 5.2° open) in the open group. There was no significant difference in reoperation rate between the 2 groups.

CONCLUSION: MIS techniques for ASD may reduce construct length, reoperation rates, blood loss, and length of stay without affecting clinical and radiographic outcomes when compared to a similar group of patients treated with open techniques.

Total disc arthroplasty and anterior cervical discectomy and fusion in cervical spine: competitive or complimentary? Review of the literature

Anterior cervical discectomy and arthrodesis has come to represent standard of care for patients with persistent radicular and/or myelopathic symptoms that have failed to improve with conservative treatments. One potential complication of the procedure is the accelerated degeneration of the vertebrae and the intervertebral discs adjacent to the level fused and the effects of fusion on those levels. The concern that fusion may be a contributing factor to accelerated adjacent segment degeneration led to increased interest in cervical disc replacement after anterior decompressive surgery. Several studies analyzing the short-term outcomes of the disc replacement procedure have been published since then, and the pros and cons of both procedures continue to remain a topic of debate among the scientific community. The analysis of published literature and our own experience has convinced us that the overall longer-term clinical outcomes after anterior cervical discectomy and fusion (ACDF) and total disc replacement (TDR) in the general patient population are not significantly different in terms of symptomatic improvement, neurological improvement, and restoration to better quality of life. Age of the patients and number of affected levels may impact the outcomes and hence determine the choice of optimum procedure. To definitely compare the incidence of adjacent segment disease after these procedures, multi-institutional studies with predetermined and unanimously agreed upon clinical and radiological criteria should be undertaken and the results analyzed in an unbiased fashion. Until that time, it is reasonable to assume that ACDF as well as cervical TDR are both safe and effective procedures that may have outcome benefits in specific patient subgroups based upon demographics and clinical/radiological parameters at the time of surgery.