Revision Surgeries at the Index Level After Cervical Disc Arthroplasty - A Systematic Review

Patient outcomes and surgical strategies in revision cervical arthroplasty following M6-C™ disc-related osteolysis

PURPOSE

Periprosthetic osteolysis from the M6-C™ Artificial Cervical Disc (Orthofix, Lewisville, Texas) has become a significant issue, sometimes requiring revision spine surgery (RSS). This study evaluates patient-reported outcome measures (PROMs) and revision strategies for managing device-related wear and osteolysis.

METHODS

PROMs, including the Visual Analogue Scale (VAS) for neck/arm pain and the Neck Disability Index (NDI), were analyzed at pre-index surgery (T1), pre-RSS (T2), and final follow-up (T3). Osteolysis severity was graded radiographically. A control group who underwent primary M6-C cervical total disc replacement (CTDR) without RSS was included for comparison.

RESULTS

Of 53 patients with M6-C CTDR, 19 (35.9%) required RSS due to osteolysis. Osteolysis grades included Grade 1 (4 patients), Grade 2 (7 patients), Grade 3 (3 patients), and Grade 4 (5 patients). Revision strategies included removal and anterior fusion, requiring vertebrectomy for Grade 4 cases; revisions to a different CTDR prosthesis were reserved for Grades 1-3. The RSS group showed significant VAS neck pain improvement at T3 (mean = 36.2 points, p < 0.001), exceeding the minimum clinically important difference (MCID). However, VAS arm pain and NDI did not meet MCID thresholds. The control group showed clinically significant improvements across all PROMs. At T2, the RSS group had a higher disability (NDI, p = 0.027) than the controls.

CONCLUSION

Revision surgery for M6-C osteolysis improves neck pain, not arm pain or disability. Early detection and tailored revision strategies are crucial to optimize patient outcomes and mitigate osteolysis-related disability.

Reoperation Strategy for Failure of Cervical Disc Arthroplasty at Index and Adjacent Levels

Cervical disc arthroplasty (CDA) is a motion-preserving alternative to anterior cervical discectomy and fusion (ACDF) for cervical degenerative disease, reducing adjacent segment degenerative disease (ASD). Despite its benefits, some patients experience CDA failure due to prosthesis-related complications, heterotopic ossification, segmental kyphosis, ASD, or facet joint degeneration, necessitating revision surgery. Reoperation strategies depend on the failure mechanism, instability, sagittal malalignment, and neural compression. Anterior revision is suited for prosthesis failure, recurrent disc herniation, or ASD, enabling prosthesis removal, decompression, and fusion. In select cases, reimplantation may restore motion. Posterior approaches are preferred for facet degeneration, multilevel stenosis, or posterior hypertrophy, with options including foraminotomy, laminoplasty, or laminectomy and fusion. Complex cases may require combined anterior and posterior surgery for optimal decompression and stability. This narrative review outlines revision strategies, emphasizing biomechanical assessment, radiographic evaluation, and patient-specific considerations. Despite surgical challenges, meticulous planning and execution can optimize outcomes.

Risk Factors for Reoperation Following Single-Level Cervical Disc Arthroplasty as Utilized in a Representative Sample of United States Clinical Practice: A Retrospective PearlDiver Study

STUDY DESIGN

Retrospective Cohort.

OBJECTIVES

Most data regarding cervical disc arthroplasty (CDA) outcomes are from highly controlled clinical trials with strict inclusion/exclusion criteria. This study aimed to identify risk factors for CDA reoperation, in "real world" clinical practice using a national insurance claims database.

METHODS

The PearlDiver database was queried for patients (2010-2020) who underwent a subsequent cervical procedure following a single-level CDA. Patients with less than 2 years follow-up were excluded. Primary outcome was to evaluate risk factors for reoperation. Secondary outcome was to evaluate the types of reoperations. Risk factors were compared using descriptive statistics. Multivariate regression analyses were used to ascertain the association among risk factors and reoperation.

RESULTS

Of 14,202 patients who met inclusion criteria, 916 (6.5%) underwent reoperation. Patients undergoing reoperation were slightly older with higher Elixhauser Comorbidity Index (ECI) scores, however both were not risk factors for reoperation. Patients with diagnoses such as smoking, myelopathy, inflammatory disorders, spinal deformity, trauma, or a history of prior cervical surgery were at greater risk for reoperation. No association was found between the year of index surgery and reoperation risk. The most common reoperation procedure was cervical fusion.

CONCLUSIONS

As billed for in the United States since 2010, CDA was associated with a 6.5% reoperation rate over a mean follow-up time of 5.3 years. Smoking, myelopathy, inflammatory disorders, spinal deformity, and a history of prior cervical surgery or trauma are risk factors for reoperation following CDA. Though patients who underwent a reoperation were older, age was not found to be an independent risk factor for a subsequent procedure.

Cervical Disk Arthroplasty: Updated Considerations of an Evolving Technology

For years, anterior cervical diskectomy and fusion has been considered the benchmark for patients with cervical radiculopathy/myelopathy. However, concerns regarding adjacent segment pathology have promoted the popularity of cervical disk arthroplasty (CDA) with its motion-preserving properties. To replicate the natural cervical disk's six degrees of freedom and compressibility in cervical spine implants, designers need to carefully consider the level of constraint for stability and material selection. Recent CDA designs have incorporated strategies to facilitate unrestricted or semirestricted motion, deploying various articulating components and materials with distinct wear and compressibility properties. To optimize outcomes, patient selection considering additional degeneration of the cervical spine is critical. Clinical long-term studies have been reported in industry-funded FDA investigational device exemption and nonindustry-funded data for one-level and two-level CDA. There are limited data available on three-level and four-level CDA. Adverse events such as heterotopic ossification, osteolysis, migration, subsidence, and failure have been described, where analysis from explanted devices yields insight into in vivo wear and impingement performance. CDA has shown short-term cost advantages, such as decreased procedural expenses. Nonetheless, long-term analysis is necessary to assess possible economic tradeoffs. Advancements in designs may lead to improved implant longevity while evidence-based decision making will guide and responsibly manage the rapid advancement in CDA technology.

Comparable long-term outcomes in patients undergoing total disc replacement or anterior cervical discectomy and noninstrumented fusion

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) is the leading surgical treatment for cervical radiculopathy. However, ACDF surgery has been suggested for to accelerate the degeneration of the adjacent cervical discs, which causes so-called adjacent segment disease (ASD). Over the past 2 decades, total disc replacement (TDR)/cervical disc arthroplasty (CDA) has become an increasingly common method for treating degenerative cervical diseases. The rationale is that a synthetic disc prosthesis may preserve motion at the operated level, which is expected to lead to reduced stress on the other cervical levels and thus decrease the risk of developing ASD. However, since the method was first introduced in the early 2000s, the long-term outcome after it is still not completely understood.

PURPOSE

Our goal was to compare the long-term outcomes of TDR and ACDF procedures.

STUDY DESIGN

Retrospective case-control study.

PATIENT SAMPLE

All patients who underwent TDR due to degenerative cervical disease at Helsinki University Hospital between 2006 and 2012 (38 patients) and matched control patients who underwent ACDF during this period (76 patients) for degenerative disc disease.

OUTCOME MEASURES

The primary outcome measure was the rate of reoperations and further cervical surgeries. Secondary outcome measures included neck symptoms (Neck Disability Index, or NDI), health-related quality of life (EQ-5D-3L), satisfaction with the surgery, radiological outcomes, and employment status.

METHODS

The medical records of all patients who underwent TDR due to degenerative cervical disease at Helsinki University Hospital between 2006 and 2012 and those of the matched control patients were analyzed retrospectively. Questionnaires were sent to all available patients at the end of the follow-up (median 14 years) to evaluate their employment status, levels of satisfaction with the surgery, current neck symptoms, and health-related quality of life. Radiological outcomes were evaluated from the cervical plain radiographs, which were taken either at the end of the follow-up as a part of the present study or earlier on for other clinical reasons, but at least 2 years after index surgery.

RESULTS

The total rate of reoperations and further cervical surgeries during the follow-up of a median of 14 years was 7/38 (18%) in the TDR group and 6/76 (8%) in the ACDF group (p=.096, ns.). Total disc replacement patients were reoperated earlier, and the 5-year reoperation rate was significantly higher in the TDR group (11% vs 1.3%, p=.026). None of the TDR patients underwent further cervical surgery more than 6 years after index surgery, whereas 5/6 (83%) of the reoperated ACDF patients were reoperated after that time. There were no significant differences in the NDIs between the patient groups. The employment rate and health-related quality of life were slightly higher in the TDR group, but the differences were statistically nonsignificant. TDR was significantly better at maintaining the angular range of motion at the operated level, and the fusion rate was significantly lower among this group.

CONCLUSIONS

There were no significant differences in the long-term outcomes of ACDF and TDR when measured by reoperation rates, employment status, NDI, EuroQoL, and satisfaction with surgery. Reoperation rate and, on the other hand, employment rate and health-related quality of life, were higher in the TDR group, but the differences were statistically nonsignificant. However, TDR patients were reoperated earlier, and the 5-year reoperation rate was significantly higher in the TDR group. Randomized long-term studies in which these methods are compared are needed to further clarify the differences between them.

Safety and Feasibility of Intradiscal Administration of Matrilin-3-Primed Adipose-Derived Mesenchymal Stromal Cell Spheroids for Chronic Discogenic Low Back Pain: Phase 1 Clinical Trial

Functionally enhanced mesenchymal stromal cells participate in the repair of intervertebral disc. This study aimed to assess the safety and tolerability of intradiscal administration of matrilin-3-primed adipose-derived stromal cell (ASC) spheroids with hyaluronic acid (HA) in patients with chronic discogenic low back pain (LBP). In this single-arm, open-label phase I clinical trial, eight patients with chronic discogenic LBP were observed over 6 months. Each patient underwent a one-time intradiscal injection of 1 mL of 6.0 × 106 cells/disc combined with HA under real-time fluoroscopic guidance. Safety and feasibility were gauged using Visual Analogue Scale (VAS) pain and Oswestry Disability Index (ODI) scores and magnetic resonance imaging. All participants remained in the trial, with no reported adverse events linked to the procedure or stem cells. A successful outcome-marked by a minimum 2-point improvement in the VAS pain score and a 10-point improvement in ODI score from the start were observed in six participants. Although the modified Pfirrmann grade remained consistent across all participants, radiological improvements were evident in four patients. Specifically, two patients exhibited reduced high-intensity zones while another two demonstrated decreased disc protrusion. In conclusion, the intradiscal application of matrilin-3-primed ASC spheroids with HA is a safe and feasible treatment option for chronic discogenic LBP.

Enhanced Intervertebral Disc Repair via Genetically Engineered Mesenchymal Stem Cells with Tetracycline Regulatory System

The therapeutic potential of Mesenchymal stem cells (MSCs) for the treatment of Intervertebral disc (IVD) degeneration can be enhanced by amplifying specific cytokines and proteins. This study aimed to investigate the therapeutic potential of tetracycline-off system-engineered tonsil-derived mesenchymal stem cells (ToMSC-Tetoff-TGFβ1-IGF1-BMP7) for treating intervertebral disc (IVD) degeneration. ToMSCs were isolated from a tonsillectomy patient and genetically modified with four distinct plasmids via CRISPR/Cas9-mediated knock-in gene editing. Transgene expression was confirmed through immunofluorescence, western blots, and an enzyme-linked immunosorbent assay for transforming growth factor beta 1 (TGFβ1) protein secretion, and the effect of MSC-TetOff-TGFβ1-IGF1-BMP7 on disc injury was assessed in a rat model. The ToMSC-Tetoff-TGFβ1-IGF1-BMP7 treatment exhibited superior therapeutic effects compared to ToMSC-TGFβ1, and ToMSC-SDF1α implantation groups, stimulating the regeneration of nucleus pulposus (NP) cells crucial for IVD. The treatment showed potential to restore the structural integrity of the extracellular matrix (ECM) by upregulating key molecules such as aggrecan and type II collagen. It also exhibited anti-inflammatory properties and reduced pain-inducing neuropeptides. ToMSC-Tetoff-TGFβ1-IGF1-BMP7 holds promise as a novel treatment for IVD degeneration. It appears to promote NP cell regeneration, restore ECM structure, suppress inflammation, and reduce pain. However, more research and clinical trials are required to confirm its therapeutic potential.

Revision Strategies for Cervical Disc Arthroplasty

STUDY DESIGN

Narrative review.

OBJECTIVE

To review indications and strategies for revision of cervical disc arthroplasty (CDA).

SUMMARY OF BACKGROUND DATA

No data were generated as part of this review.

METHODS

A narrative review of the literature was performed.

RESULTS

No results were generated as part of this review.

CONCLUSIONS

CDA is a proven, motion-sparing surgical option for the treatment of myelopathy or radiculopathy secondary to cervical degenerative disc disease. As is the case with any operation, a small percentage of CDA will require revision, which can be a technically demanding endeavor. Here we review available revision strategies and associated indications, a thorough understanding of which will aid the surgeon in finely tailoring their approach to varying presentations.

Impact of Posterior Cervical Foraminotomy Before or After Cervical Disk Replacement: Current Evidence

STUDY DESIGN

Narrative review.

OBJECTIVES

The purpose of this study was to provide a review of the current evidence on the impact of posterior cervical foraminotomy (PCF) performed before or after cervical disk replacement (CDR).

SUMMARY OF BACKGROUND DATA

The impact of PCF on outcomes in the setting of CDR is an evolving field, given the recent widespread adoption of CDR and the relative rarity of patients who have undergone both procedures.

METHODS

A literature search was conducted using PubMed to determine current evidence regarding the indications, outcomes, and biomechanical effects of CDR and PCF when performed alone or in combination.

RESULTS

When radicular symptoms persist following PCF, a CDR can be safely performed to provide further decompression. Conversely, a PCF can be safely performed following CDR for these same indications. The biomechanical effects of these procedures in combination demonstrate maintained stability when the facetectomy is less than 50% of the facet joint. Studies demonstrate that stability is not significantly decreased by the presence, amount, or level of posterior foraminotomies in the setting of CDR.

CONCLUSIONS

A PCF can be safely performed before or after cervical disk arthroplasty for recurrent radicular symptoms.

LEVEL OF EVIDENCE

Level V.

Clinical Effectiveness of Artificial Disc Replacement in Comparison With Anterior Cervical Discectomy and Fusion in the Patients With Cervical Myelopathy: Systematic Review and Meta-analysis

OBJECTIVE

Cervical myelopathy (CM) describes the compressive cervical spinal cord state, often accompanied by serious clinical condition, by herniated disc or hypertrophied spurs or ligament. Anterior cervical discectomy and fusion (ACDF) has been frequently employed as conventional surgical solution for this CM despite its inherent biomechanical handicap. Alternatively, an artificial disc replacement (ADR) preserves cervical motion while still decompressing the spinal canal and neural foramen. This analysis elaborated to clarify the potential benefits of ADR application to CM over ACDF from the conglomerated results of the past references.

METHODS

A literature search was performed using MEDLINE, Embase, Cochrane review, and KMbase databases from the studies published until March 2023. Six studies (3 randomized controlled study [RCTs] and 3 non-RCTs) were included in a qualitative and quantitative synthesis. Data were extracted and analyzed using a random effects model to obtain effect size and its statistical significance. Quality assessment and evidence level were established in accordance with the GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology.

RESULTS

Among 6 studies, 2 studies showed that ADR group achieved significantly better clinical improvement than the ACDF group, while the rest 4 studies revealed no significant difference. A meta-analysis showed better clinical outcomes with or without statistical significance. The level of evidence was low because of inconsistency and imprecision.

CONCLUSION

ADR was superior or at least, not inferior to ACDF in terms of functional recovery. However, its application to the CM patients is merely empowered with weak strength due to low level of evidence.

Observational, Multicenter Study of the Efficacy and Safety of Cervical Disk Arthroplasty With Mobi-C in the Treatment of Cervical Degenerative Disk Disease. Results at 10 years Follow-Up

BACKGROUND

Cervical disk arthroplasty replacement (CDA) was developed to avoid specific disadvantages of cervical fusion. The purpose of this paper is to provide 10-year follow-up results of an ongoing prospective study after CDA.

METHODS

Three hundred eighty-four patients treated using the Mobi-C (ZimVie, Troyes, France) were included in a prospective multicenter study. Routine clinical and radiologic examinations were reported preoperatively and postoperatively with up to 10-year follow-up. Complications and revision surgeries were also documented.

RESULTS

At 10 years showed significant improvement in all clinical outcomes [Neck Disability Index, visual analog scale (VAS) for arm and neck pain, physical component summary of SF36, and mental component summary of SF36). Motion at the index level increased significantly over baseline (mean range of motion=7.6 vs. 8 degrees at five years and 6.0 degrees preoperatively; P <0.001) and 71.3% of the implanted segments remained mobile (range of motion>3 degrees). Adjacent disks were also mobile at 10 years with the same mobility as preoperatively. At 10 years, 20.9% of the implanted segments demonstrated no heterotopic ossification. Thirty-four patients (8.9%) experienced 41 adverse events, with or without reoperation during the first five years. We found only two additional surgeries after five years. We observed an increased percentage of working patients and a decrease in medication consumption. Regarding the overall outcome, 94% of patients were satisfied.

CONCLUSIONS

Our 10-year results showed significant improvement in all clinical outcomes, with low rates of revision or failure. This experience in patients with long-term follow-up after CDA endorses durable, favorable outcomes in properly selected patients.

Combining Virtual Surgical Planning and Patient-Specific 3D-Printing as a Solution to Complex Spinal Revision Surgery

With the advent of three-dimensional printing, rapid growth in the field and application in spinal and orthopedic surgery has been seen. This technology is now being applied in creating patient-specific implants, as it offers benefits over the generic alternative, with growing literature supporting this. This report details a unique application of virtual surgical planning and manufacture of a personalized implant in a case of cervical disc replacement failure with severe osteolysis and resultant hypermobility. Where this degree of degenerative bone loss would often necessitate a vertebrectomy to be performed, this case highlights the considerable customizability of 3D-printed patient-specific implants to contour to the bony defects, allowing for a smaller and safer operation, with the achievement of stability as early as 3 months after the procedure, by the presence of osseointegration. With increasing developments in virtual planning technology and 3D printing ability, the future of complex spinal revision surgery may adopt these technologies as it affords the patient a faster, safer, and less invasive and destructive procedure.

The Effect of Subsidence on Segmental and Global Lordosis at Long-term Follow-up After Anterior Cervical Discectomy and Fusion

OBJECTIVE

Subsidence following anterior cervical discectomy and fusion (ACDF) may lead to disruptions of cervical alignment and lordosis. The purpose of this study was to evaluate the effect of subsidence on segmental, regional, and global lordosis.

METHODS

This was a retrospective cohort study performed between 2016-2021 at a single institution. All measurements were performed using lateral cervical radiographs at the immediate postoperative period and at final follow-up greater than 6 months after surgery. Associations between subsidence and segmental lordosis, total fused lordosis, C2-7 lordosis, and cervical sagittal vertical alignment change were determined using Pearson correlation and multivariate logistic regression analyses.

RESULTS

One hundred thirty-one patients and 244 levels were included in the study. There were 41 one-level fusions, 67 two-level fusions, and 23 three-level fusions. The median follow-up time was 366 days (interquartile range, 239-566 days). Segmental subsidence was significantly negatively associated with segmental lordosis change in the Pearson (r = -0.154, p = 0.016) and multivariate analyses (beta = -3.78; 95% confidence interval, -7.15 to -0.42; p = 0.028) but no associations between segmental or total fused subsidence and any other measures of cervical alignment were observed.

CONCLUSION

We found that subsidence is associated with segmental lordosis loss 6 months following ACDF. Surgeons should minimize subsidence to prevent long-term clinical symptoms associated with poor cervical alignment.

Cervical Radiculopathy: Focus on Factors for Better Surgical Outcomes and Operative Techniques

For patients with cervical radiculopathy, most studies have recommended conservative treatment as the first-line treatment; however, when conventional treatment fails, surgery is considered. A better understanding of the prognosis of cervical radiculopathy is essential to provide accurate information to the patients. If the patients complain of persistent and recurrent arm pain/numbness not respond to conservative treatment, or exhibit neurologic deficits, surgery is performed using anterior or posterior approaches. Anterior cervical discectomy and fusion (ACDF) has historically been widely used and has proven to be safe and effective. To improve surgical outcomes of ACDF surgery, many studies have been conducted on types of spacers, size/height/position of cages, anterior plating, patients' factors, surgical techniques, and so forth. Cervical disc replacement (CDR) is designed to reduce the incidence of adjacent segment disease during long-term follow-up by maintaining cervical spine motion postoperatively. Many studies on excellent indications for the CDR, proper type/size/shape/height of the implants, and surgical techniques were performed. Posterior cervical foraminotomy is a safe and effective surgical option to avoid complications associated with anterior approach and fusion surgery. Most recent literature demonstrated that all three surgical techniques for patients with cervical radiculopathy have clear advantages and disadvantages and reveal satisfactory surgical outcomes under a proper selection of patients and application of appropriate surgical methods. For this, it is important to fully understand the factors for better surgical outcomes and to adequately practice the operative techniques for patients with cervical radiculopathy.

Anterior Cervical Foraminotomy for Radiculopathy After Cervical Artificial Disc Replacement: Technique Description and Case Report

BACKGROUND

Patients may occasionally have persistent or recurrent radicular symptoms after cervical artificial disc replacement (ADR) for cervical spondylotic radiculopathy. We describe our approach using anterior cervical foraminotomy (ACF) to provide symptom relief in such patients without the need to convert to a fusion or remove the ADR implant.

METHODS

Our operative technique for ACF after cervical ADR begins by starting at the lateral edge of the ADR at the superior end plate of the inferior vertebral body. The ipsilateral uncovertebral joint is drilled with a combination of a high-speed burr and diamond-coated burr to minimize the risk of injury to the vertebral artery. The neuroforamen is entered after drilling through the posterior aspect of the uncinate process. The exiting cervical nerve root should be directly visualized, and a Kerrison rongeur may be used to trace along the nerve root laterally to remove any remaining uncinate osteophyte or process. We queried our internal database for patients with recurrent or new radicular pain following cervical ADR who underwent ACF. Clinical characteristics and outcomes were reported.

RESULTS

Five patients with recurrent radicular symptoms after ADR were reviewed. Two ACFs were performed at C5-6, and 2 were performed at C6-7. Four patients developed ipsilateral recurrent radicular symptoms, and only 1 patient developed contralateral new radicular symptoms. Three patients reported complete resolution of their new or recurrent radicular symptoms following ACF, and 2 patients reported only partial resolution. No patients required conversion to a fusion.

CONCLUSIONS

In patients with recurrent symptoms of cervical spondylotic radiculopathy following ADR, ACF with uncovertebral joint resection can be used to provide direct foraminal decompression without the need for implant removal. This approach also preserves motion at the affected level, preserves cervical spinal stability, and prevents the need for spinal fusion.

CLINICAL RELEVANCE

Patients with persistent or recurrent radicular symptoms after cervical ADR may achieve resolution of symptoms through a modified ACF technique.

LEVEL OF EVIDENCE: 4