Bone morphogenetic protein in complex cervical spine surgery: A safe biologic adjunct?

Analysis of reasons for medical malpractice litigation due to anterior cervical discectomy and fusion

Background

Anterior cervical discectomy and fusions (ACDF) are among the most common cervical spine operations, with over 137,000 surgeries performed annually. Understanding reasons underlying malpractice pertaining to ACDF may inform physicians of practices to improve delivery of patient care and mitigate malpractice. The aim of our study was to analyze the causes and outcomes for lawsuits pertaining to ACDF.

Methods

The Westlaw Edge and Verdict Search databases were queried for malpractice claims utilizing the keywords "anterior cervical discectomy and fusion" and "ACDF". Inclusion criteria was based on relevance of case grievance(s) to ACDF. Data collected included date of case hearing, plaintiff demographics, defendant specialty, verdict ruling, location of filed claim, monetary award, and sustained injuries.

Results

Fifty cases were included in this study after excluding 1933 cases. Of the 50 cases, 34 (68%) resulted in a defendant outcome, 8 (16%) resulted in a plaintiff outcome, and 8 (16%) resulted in settlement. Plaintiff verdicts resulted in an average monetary payment of $9.70 million, while settlements resulted in an average payment of $2.06 million. Reasons for litigation were divided into 10 categories, most commonly improper postoperative management (20%), hardware failure (18%), intraoperative error (14%), off-label use of implants (14%), and insufficient informed consent (12%).

Conclusions

Malpractice claims due to ACDF are associated with higher frequencies of plaintiff verdicts and higher monetary costs compared to other spinal surgery procedures. There does not appear to be supporting evidence that spinal cord neuromonitoring is mandatory for ACDF procedures from a medicolegal standpoint.

Trends, payments, and costs associated with BMP use in Medicare beneficiaries undergoing spinal fusion

BACKGROUND CONTEXT

Bone morphogenic protein (BMP) promotes bony fusion but increases costs. Recent trends in BMP use among Medicare patients have not been well-characterized.

PURPOSE

To assess utilization trends, complication, payments, and costs associated with BMP use in spinal fusion in a Medicare-insured population.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Total of 316,070 patients who underwent spinal fusion in a 20% sample of Medicare-insured patients, 2006 to 2015.

OUTCOME MEASURES

Utilization trends across time and geography, complications, payments, and costs.

METHODS

Patients were stratified by fusion type and diagnosis. Multivariable logistic and linear regression were used to adjust for the effect of baseline characteristics on complications and total payments or cost, respectively.

RESULTS

BMP was used in 60,249 cases (19.1%). BMP utilization rates decreased from 23.1% in 2006 to 12.0% in 2015, most significantly in anterior cervical (7.5%-3.1%), posterior cervical (17.0%-8.3%), and posterior lumbar fusions (31.5%-15.8%). There are significant state- and region-level geographic differences in BMP utilization. Across all years, states with the highest BMP use were Indiana (28.5%), Colorado (26.6%), and Nevada (25.7%). States with the lowest BMP use were Maine (2.3%), Vermont (8.2%), and Mississippi (10.4%). After multivariate risk adjustment, BMP use was associated with decreased overall complications in thoracic (odds ratios [OR] [95% confidence intervals [CI]): 0.89 [0.81-0.99]) and anterior lumbar fusions (OR [95% CI]: 0.89 [0.84-0.95]), as well as increased reoperation rates in anterior cervical (OR [95% CI]: 1.11 [1.04-1.19]), posterior cervical (OR (95% CI): 1.14 (1.04-1.25)), thoracic (OR (95% CI): 1.32 (1.23-1.41)), and posterior lumbar fusions (OR (95% CI): 1.11 (1.06-1.16)). BMP use was also associated with greater total costs, independent of fusion type, after multivariate risk adjustment (p<.0001). Payments, however, were comparable between groups in anterior and posterior cervical fusion with or without BMP. BMP use was associated with greater total payments in thoracic, anterior lumbar, and posterior lumbar fusions. Notably, the difference in payments was smaller than the associated cost increase in all fusion types.

CONCLUSIONS

BMP use has declined across all fusion types over the last decade, after a peak in 2007. While BMP is associated with greater costs, reimbursement does not increase proportionally with BMP cost.

Long-Term Assessment of Bone Regeneration in Nonunion Fractures Treated with Compression-Resistant Matrix and Recombinant Human Bone Morphogenetic Protein-2 in Dogs

OBJECTIVE

 The aim of this study was to assess bone density, bone architecture and clinical function of canine nonunion distal appendicular long bone fractures with a defect treated with fixation, compression-resistant matrix and recombinant human bone morphogenetic protein-2 (rhBMP-2).

STUDY DESIGN

 Prospective cohort study with dogs at least 1-year post treatment. Computed tomography was performed and quantitative measurements from previous fracture sites were compared with measurements from contralateral limbs. Subjective evaluation included gait assessment and palpation.

RESULTS

 Six patients met the inclusion criteria. The rhBMP-2 treated bone exhibited higher density at the periphery and lower density in the centre, similar to the contralateral limb. All patients were weight bearing on the treated limb and all fractures were healed.

CONCLUSION

 The rhBMP-2-treated bone underwent restoration of normal architecture and density. Acceptable limb function was present in all patients. The results of this study can serve as a basis for long-term response in treating nonunion fractures in veterinary patients.

Pseudarthrosis of the Cervical Spine

Pseudarthrosis of the cervical spine represents a common and challenging problem for spine surgeons. Rates vary greatly from as low as 0%-20% to >60% and depend heavily on patient factors, approach, and number of levels. While some patients remain asymptomatic from pseudarthrosis, many require revision surgery due to instability, continued neck pain, or radiculopathy/myelopathy. We aimed to provide a practical, narrative review of cervical pseudarthrosis to address the following areas: (1) definitions, (2) incidence, (3) risk factors, (4) presentation and workup, (5) treatment decision-making, and (6) postoperative care. It is our hope the current review provides a concise summary for how to diagnose and treat challenging cervical nonunions.

Soft tissue swelling incidence using demineralized bone matrix in the outpatient setting

AIM

To assess use of demineralized bone matrix (DBM) use in anterior cervical discectomy and fusion (ACDF) in outpatient setting.

METHODS

One hundred and forty-five patients with prospectively collected data undergoing single and two level ACDF with DBM packed within and anterior to polyetheretherketone (PEEK) cages. Two groups created, Group 1 (75) outpatients and control Group 2 (70) hospital patients. Prevertebral soft tissue swelling (PVSTS) was measured anterior to C2 and C6 on plain lateral cervical radiographs preoperatively and one week postoperatively and fusion assessed at two years.

RESULTS

There was no intergroup significance between preoperative and postoperative visual analogue scales (VAS) and neck disability index (NDI) scores between Group 1 and 2. Mean preoperative PVSTS in Group 1 was 4.7 ± 0.2 mm at C2 level and 11.1 ± 0.5 at C6 level compared to Group 2 mean PVSTS of 4.5 ± 0.5 mm and 12.8 ± 0.5, P = 0.172 and 0.127 respectively. There was no radiographic or clinical evidence of adverse reaction noted. In Group 1 mean postoperative PVSTS was 5.5 ± 0.4 mm at C2 and 14.9 ± 0.6 mm at C6 compared Group 2 mean PVSTS was 4.9 ± 0.3 mm at C2 and 14.8 ± 0.5 mm at C6, P = 0.212 and 0.946 respectively. No significant increase in prevertebral soft tissue space at C2 and C6 level demonstrated.

CONCLUSION

ACDF with adjunct DBM packed PEEK cages showed a statistical significant intragroup improvement in VAS neck pain scores and NDI scores (P = 0.001). There were no reported serious patient complications; post-operative radiographs demonstrated no significant difference in prevertebral space. We conclude that ACDF with DBM-packed PEEK cages can be safely done in an ASC with satisfactory outcomes.

Use of Allogenic Mesenchymal Cellular Bone Matrix in Anterior and Posterior Cervical Spinal Fusion: A Case Series of 21 Patients

Study Design

Retrospective case series.

Purpose

To report our early experience using allogenic mesenchymal cellular bone matrix (CBM) products in cervical spine fusion.

Overview of Literature

Multi-level cervical fusions have historically yielded lower fusion rates than single level fusions, especially in patients with high risk medical comorbidities. At this time, significant literature in cervical fusion outcomes with this cellular allograft technology is lacking.

Methods

Twenty-one patients underwent either multilevel (3 or 4 level) anterior cervical discectomy and fusion, anterior cervical corpectomy and fusion, or posterior cervical fusion. ViviGen (DePuy Synthes Spine, Raynham, MA, USA), an allogenic bone matrix product, was used in addition to standard instrumentation. Radiographic evaluation was performed at 2 weeks, 12 weeks, 24 weeks and 1 year postoperative. Visual analog scale (VAS) and neck disability index (NDI) scores along with return to work and leisure activity were recorded.

Results

At 6 months postoperative, all patients had radiographic evidence of bone fusion regardless of age or medical comorbidities. All patients reported subjective improvement with a mean decrease in VAS from 8.3 to 1.5 and a mean decrease in NDI from 40.3% to 6.0% at 1 year. All patients also returned to work and/or regular leisure activity within 3 months.

Conclusions

Twenty-one patients undergoing high-risk anterior and posterior cervical spine fusion, with the use of a commercially available mesenchymal CBM product, went on to radiographic fusion and all had improvement in subjective outcomes. While further effort and research is needed to validate its widespread use, this study shows favorable use of CBM in cervical fusion for high-risk cases.

Can Dysphagia Following Anterior Cervical Fusions With rhBMP-2 Be Reduced With Local Depomedrol Application?: A Prospective, Randomized, Placebo-Controlled, Double-Blind Trial

STUDY DESIGN

A prospective, randomized, placebo-controlled, double-blind trial.

OBJECTIVE

The aim of this study was to investigate whether the local administration of depomedrol decreases the severity of dysphagia after anterior cervical discectomy and fusion (ACDF) surgery using bone morphogenetic protein (BMP).

SUMMARY OF BACKGROUND DATA

Although recombinant human BMP-2 is effective in promoting arthrodesis, many physicians avoid using it in anterior cervical spine fusions due to concern for increased incidence of dysphagia, significant pre-vertebral swelling, and airway compromise. Pilot studies have shown that the local application of depomedrol may decrease the incidence of postoperative dysphagia. We performed a prospective, randomized trial to evaluate the efficacy of local depomedrol application in reducing the severity of postoperative dysphagia following anterior cervical fusions using low-dose rhBMP-2. We hypothesized that locally administered depomedrol reduces dysphagia following such surgeries.

METHODS

Fifty patients between 18 and 70 years of age, undergoing 1, 2, and 3-level ACDFs, were randomized to 1 of 2 groups: BMP-2 with depomedrol or BMP-2 with saline. Patients were followed for 4 weeks postoperatively by the study administrator. Dysphagia was measured at 5 time intervals (postoperative days 1, 4, 7, 14, and 28) using a 4-point Modified Dysphagia Scoring System. Additional data regarding overall length of hospital stay and the administration of dysphagia-directed treatments were also recorded.

RESULTS

Twenty-seven patients were randomized to the treatment (depomedrol) group and 23 were randomized to the control (saline) group. The 2 groups were nearly identical in terms of their demographic and operative characteristics. Patients receiving depomedrol experienced decreased dysphagia incidence and magnitude at all time intervals, with differences reaching statistical significance on postoperative days 4, 7, 14, and 28 (P < 0.05).

CONCLUSION

This study provides Level 1 evidence that locally administered depomedrol on a collagen sponge significantly decreases postoperative dysphagia incidence and magnitude following anterior cervical spine fusion using low-dose rhBMP-2.

LEVEL OF EVIDENCE

1.

Mesenchymal stem cell allograft as a fusion adjunct in one- and two-level anterior cervical discectomy and fusion: a matched cohort analysis

BACKGROUND CONTEXT

Live mesenchymal stem cell (MSC) allograft-containing allogeneic bone grafts have recently gained popularity and currently account for greater than 17% of all bone grafts and bone graft substitutes used in spinal surgery. Although the claim of cellular bone matrices containing osteogenic cells with osteoinductive properties is attractive, little is known about their clinical success when used in anterior cervical discectomy and fusion (ACDF).

PURPOSE

The objective of this study was to report on the radiographic fusion rates in one- and two-level instrumented ACDF using an MSC.

STUDY DESIGN/SETTING

This was a retrospective review of prospectively matched cohort of patients with radiologic assessment of fusion as the primary end point.

PATIENT SAMPLE

Two matched cohorts of adult patients who underwent ACDF with MSC or standard allograft were included.

OUTCOMES MEASURES

The outcome measures included radiographic and clinical evidence of healing at 1 year.

METHODS

A consecutive series of 57 patients who underwent a one- or two-level instrumented ACDF procedure between 2010 and 2012 were retrospectively analyzed. All fusion constructs comprised an interbody allograft, an anterior plate, and Osteocel (NuVasive, San Diego, CA, USA). These patients were matched to a control group of 57 patients.

RESULTS

Of the 57 cases in both cohorts, 29 (50.9%) were single-level, and 28 (49.1%) were two-level instrumented ACDFs. There were no significant differences in patient age (p=.71), gender, comorbidity burden (Charlson Comorbidity Index [CCI]: 1.95; 2.42, p=.71) or body mass index (p=.79). At the 1-year follow-up, 50 of 57 (87.7%) patients in the Osteocel cohort demonstrated a solid fusion compared with 54 of 57 (94.7%) in the control group (p=.19). Seven (12.3%) patients in the Osteocel cohort were reported as having a failed fusion at 1 year.

CONCLUSIONS

This is the first non-industry sponsored study to analyze a matched cohort assessing the 1-year arthrodesis rates associated with a nonstructural MSC allograft in one- and two-level ACDF procedures. Although not statistically significant, patients treated with MSC allografts demonstrated lower fusion rates compared with a matched non-MSC cohort.

Effects of sequentially released BMP-2 and BMP-7 from PELA microcapsule-based scaffolds on the bone regeneration

Osteoinductive biomaterials are helpful for the therapy of large bone defects and provide an alternative to autogenous bone and allografts. Recently, multiple growth factors are delivered to mimic the natural process of bone healing in the bone tissue engineering. Herein, we investigated the effects of sequential released bone morphogenetic protein-2 (BMP-2) and bone morphogenetic protein-7 (BMP-7) from polylactide-poly (ethylene glycol)-polylactide (PELA) microcapsule-based scaffolds on the bone regeneration. Through improving the double emulsion/solvent evaporation technique, BMP-7 was encapsulated in PELA microcapsules, to the surface of which BMP-2 was attached. Then, the scaffold (BMP-2/PELA/BMP-7) was fused by these microcapsules with dichloromethane vapor method. In vitro, it sequentially delivered bioactive BMP-2 and BMP-7 and partially imitated the profile of BMPs expression during the fracture healing. To determine the bioactivity of released BMP-2 and BMP-7, alkaline phosphatase (AKP) activity was analyzed in MC3T3-E1 cells. When compared with simple BMP-2 plus BMP-7group and pure PELA group, the AKP activity in BMP-2/PELA/BMP-7 group significantly increased. MTT assay indicated the BMP-loaded PELA scaffold had no adverse effects on cell activity. In addition, the effects of BMP-loaded scaffolds were also investigated in a rat femoral defect model by micro-computed tomographic (mCT) and histological examination. At 4 and 8 weeks post-implantation, BMP-2/PELA/BMP-7 significantly promoted osteogenesis as compared to other groups. The scaffold underwent gradual degradation and replacement by new bones at 8 weeks. Our findings suggest that the sequential release of BMP-2 and BMP-7from PELA microcapsule-based scaffolds is promising for the therapy of bone defects.

The use of bone morphogenetic protein in thoracolumbar spine procedures: analysis of the MarketScan longitudinal database

BACKGROUND CONTEXT

The use of recombinant human bone morphogenetic protein (BMP) in the thoracolumbar spine remains controversial, with many questioning the risks and benefits of this new biologic.

PURPOSE

To describe national trends, incidence of complications, and revision rates associated with BMP use in thoracolumbar spine procedures.

STUDY DESIGN/SETTING

Administrative database study.

PATIENT SAMPLE

A matched cohort of 52,259 patients undergoing thoracolumbar fusion surgery from 2006 to 2010 were identified in the MarketScan database. Patients without BMP treatment were matched 2:1 to patients receiving intraoperative BMP.

OUTCOME MEASURES

Revision rates and postoperative complications.

METHODS

The MarketScan database was used to select patients undergoing thoracolumbar fusion procedures, with and without intraoperative BMP. We ascertained outcome measures using either International Classification of Disease, ninth revision, or Current Procedural Terminology coding, and matched groups were evaluated using a bivariate and multivariate analyses. Kaplan-Meier estimates of fusions failure rates were also calculated.

RESULTS

Patients receiving intraoperative BMP underwent fewer refusions, decompressions, posterior and anterior revisions, or any revision procedure (single level 4.53% vs. 5.85%, p<.0001; multilevel 5.02% vs. 6.83%, p<.0001; overall cohort 4.73% vs. 6.09%, p<.0001). After adjusting for comorbidities, demographics, and levels of procedure, BMP was not associated with the postoperative development of cancer (odds ratio 0.92). Bone morphogenetic protein use was associated with an increase in any complication at 30 days (15.8% vs. 14.9%, p=.0065), which is only statistically significant among multilevel procedures (19.74% vs. 18.02%, p=.0013). Thirty-day complications in multilevel procedures associated with BMP use included new dysrhythmia (4.68% vs. 4.01%, p=.0161) and delirium (1.08% vs. 0.69%, p=.0024). A new diagnosis of chronic pain was associated with BMP use in both single-level (2.74% vs. 2.15%, p=.0019) and multilevel (3.7% vs. 2.52%, p<.0001) procedures. Bone morphogenetic protein was negatively associated with infection in single-level procedures (2.12% vs. 2.64%, p=.0067) and wound dehiscence in multilevel procedures (0.84% vs. 1.18%, p=.0167).

CONCLUSIONS

In national data analysis of thoracolumbar procedures, we found that BMP was associated with decreased incidence of revision spinal surgery and with a slight increased risk of overall complications at 30 days. Although no BMP-associated increased risk of malignancy was found, lack of long-term follow-up precludes detection of between-group differences in malignancies and other rare events that may not appear until later.

Fixation with C-2 laminar screws in occipitocervical or C1-2 constructs in children 5 years of age or younger: a series of 18 patients

OBJECT.: There are rare indications for upper cervical spine fusion in young children. Compared with nonrigid constructs, rigid instrumentation with screw fixation increases the fusion rate and reduces the need for halo fixation. Instrumentation may be technically challenging in younger children. A number of screw placement techniques have been described. Use of C-2 translaminar screws has been shown to be anatomically feasible, even in the youngest of children. However, there are few data detailing the clinical outcome. In this study, the authors describe the clinical and radiographic follow-up of 18 children 5 years of age or younger who had at least one C-2 translaminar screw as part of an occipitocervical or C1-2 fusion construct.

METHODS

A retrospective review of all children treated with instrumented occipitocervical or C1-2 fusion between July 1, 2007, and June 30, 2013, at Riley Children's Hospital and Texas Children's Hospital was performed. All children 5 years of age or younger with incorporation of at least one C-2 translaminar screw were identified.

RESULTS

Eighteen children were studied (7 boys and 11 girls). The mean age at surgery was 38.1 months (range 10-68 months). Indications for surgery included traumatic instability (6), os odontoideum (3), destructive processes (2), and congenital instability (7). A total of 24 C-2 translaminar screws were placed; 23 (95.8%) of 24 were satisfactorily placed (completely contained within the cortical walls). There was one medial cortex breach without neurological impingement. There were no complications with screw placement. Three patients required wound revisions. Two patients died as a result of their original condition (trauma, malignant tumor). The mean follow-up duration for the surviving patients was 17.5 months (range 3-60 months). Eleven (91.7%) of the 12 patients followed for 6 months or longer showed radiographic stability or completed fusion.

CONCLUSIONS

Use of C-2 translaminar screws provides an effective anchor for internal fixation of the upper cervical spine. In this study of children 5 years of age or younger, the authors found a high rate of radiographic fusion with a low rate of complications.