Lumbar disc replacement surgery-successes and obstacles to widespread adoption

Prosthesis optimization and mechanical analysis of artificial lumbar disc replacement

BACKGROUND

Artificial lumbar disc replacement is an effective method for the treatment of lumbosacral degenerative diseases. An appropriate artificial intervertebral disc device is of great significance for the maintenance of spinal stability and activity.

METHODS

Two finite element models of ProDisc-L prosthesis replacement and improved prosthesis replacement were constructed by using the finite element model of complete lumbar L1-L5 segment established by CT image data. The mechanical properties of the surgical models before and after improvement were analyzed and evaluated.

RESULTS

The ProDisc-L group and the improved group showed similar lumbar's ROM and maintained a similar ROM with the normal lumbar spine. There was no significant change in the intervertebral disc's pressure between the adjacent segments of the two prosthesis groups compared with the normal group, but the stress value of the improved prosthesis group was slightly lower than that of the ProDisc-L group. In addition, the improved prosthesis replacement has more reasonable stress distribution.

CONCLUSIONS

Compared with the ProDisc-L prosthesis, the improved prosthesis can reduce the pressure in the intervertebral disc of the adjacent segment, the contact stress of the facet joint and the artificial prosthesis, which provides reference for the subsequent design of the prosthesis structure.

Lumbar Total Disc Replacements for Degenerative Disc Disease: A Systematic Review of Outcomes With a Minimum of 5 years Follow-Up

STUDY DESIGN

Systematic Review.

OBJECTIVES

To systematically review the clinical outcomes, re-operation, and complication rates of lumbar TDR devices at mid-to long-term follow-up studies for the treatment of lumbar degenerative disc disease (DDD).

METHODS

A systematic search was conducted on PubMed, SCOPUS, and Google Scholar to identify follow-up studies that evaluated clinical outcomes of lumbar TDR in patients with DDD. The included studies met the following criteria: prospective or retrospective studies published from 2012 to 2022; a minimum of 5 years post-operative follow-up; a study sample size >10 patients; patients >18 years of age; containing clinical outcomes with Oswestry Disability Index (ODI), Visual Analog Scale (VAS), complication or reoperation rates.

RESULTS

Twenty-two studies were included with data on 2284 patients. The mean follow-up time was 8.30 years, with a mean follow-up rate of 86.91%. The study population was 54.97% female, with a mean age of 42.34 years. The mean VAS and ODI pain score improvements were 50.71 ± 6.91 and 30.39 ± 5.32 respectively. The mean clinical success and patient satisfaction rates were 74.79% ± 7.55% and 86.34% ± 5.64%, respectively. The mean complication and reoperation rates were 18.53% ± 6.33% and 13.6% ± 3.83%, respectively. There was no significant difference when comparing mid-term and long-term follow-up studies for all clinical outcomes.

CONCLUSIONS

There were significant improvements in pain reduction at last follow-up in patients with TDRs. Mid-term follow-up data on clinical outcomes, complication and reoperation rates of lumbar TDRs were maintained longer term.

Management Considerations for Total Intervertebral Disc Replacement

The burden of disease regarding lumbar and cervical spine pain is a long-standing, pervasive problem within medicine that has yet to be resolved. Specifically, neck and back pain are associated with chronic pain, disability, and exorbitant health care use worldwide, which have only been exacerbated by the increase in overall life years and chronic disease. Traditionally, patients with significant pain and disability secondary to disease of either the cervical or lumbar spine are treated via fusion or discectomy. Although these interventions have proved curative in the short-term, numerous longitudinal studies evaluating the efficacy of traditional management have reported severe impairment of normal spinal range of motion, as well as postoperative complications, including neurologic injury, radiculopathy, osteolysis, subsidence, and infection, paired with less than desirable reoperation rates. Consequently, there is a call for innovation and improvement in the treatment of lumbar and cervical spine pain, which may be answered by a modern technique known as intervertebral disc arthroplasty, or total disc replacement (TDR). Thus, this review aims to describe the management strategy of TDR and to explore updated considerations for its use in practice, both to help guide clinical decision making.

The role of biomechanical factors in models of intervertebral disc degeneration across multiple length scales

Low back pain is the leading cause of disability, producing a substantial socio-economic burden on healthcare systems worldwide. Intervertebral disc (IVD) degeneration is a primary cause of lower back pain, and while regenerative therapies aimed at full functional recovery of the disc have been developed in recent years, no commercially available, approved devices or therapies for the regeneration of the IVD currently exist. In the development of these new approaches, numerous models for mechanical stimulation and preclinical assessment, including in vitro cell studies using microfluidics, ex vivo organ studies coupled with bioreactors and mechanical testing rigs, and in vivo testing in a variety of large and small animals, have emerged. These approaches have provided different capabilities, certainly improving the preclinical evaluation of these regenerative therapies, but challenges within the research environment, and compromises relating to non-representative mechanical stimulation and unrealistic test conditions, remain to be resolved. In this review, insights into the ideal characteristics of a disc model for the testing of IVD regenerative approaches are first assessed. Key learnings from in vivo, ex vivo, and in vitro IVD models under mechanical loading stimulation to date are presented alongside the merits and limitations of each model based on the physiological resemblance to the human IVD environment (biological and mechanical) as well as the possible feedback and output measurements for each approach. When moving from simplified in vitro models to ex vivo and in vivo approaches, the complexity increases resulting in less controllable models but providing a better representation of the physiological environment. Although cost, time, and ethical constraints are dependent on each approach, they escalate with the model complexity. These constraints are discussed and weighted as part of the characteristics of each model.

Observations of bony ongrowth and clinical fixation in two retrieved disc replacements

Total disc replacements utilize textured coatings to maximize bony ongrowth. However, the contribution of direct bony attachment to overall fixation for total disc replacements has not been reported. The goal of the present study was to document the extent of bony attachment to the surfaces of two clinically functional total disc replacements that were securely fixed at the time of revision. Two metal-and-polymeric disc replacements, one cervical and one lumbar, were evaluated following surgical retrieval. The cervical device was retrieved at 8 months and the lumbar device at 28 months post-operative. Both devices were reported well-fixed at the time of removal, with large bone masses attached to one endplate of each device. Visual inspections, non-destructive gravimetric measurements, and surface metrology were performed to assess fixation. These inspections suggested that both devices had been fixed at the time of removal with little in vivo mechanical damage, as surgical extraction damage was noted on both devices and provided imaging showed a lack of device migration. Devices were then embedded and sectioned to evaluate the bone-implant interface. High resolution photographs and contact microradiographs were taken to assess bony attachment. In contrast to initial analysis, these images revealed radiolucent gaps between the endplates and bone masses. Little direct contact between the bone and endplate surface was identified and the original surgical cuts were still visible. Both devices were clinically fixed at the time of removal and neither had complications associated with loosening. However, osseointegration was minimal in one of the devices and altogether absent from the other. The findings of the present study suggest that other factors may influence overall clinical fixation such as the surgical preparation of the vertebral bone or the surface roughness of the treated endplates. Despite the limitations of the present study, this information is unique to the current total disc replacement literature and the ongrowth and fixation of devices should be considered as a topic for future investigation.

The role of spinal surgery in the treatment of low back pain

Low back pain (LBP) is common and a leading cause of disability and lost productivity worldwide. Acute LBP is frequently self-resolving, but recurrence is common, and a significant proportion of patients will develop chronic pain. This transition is perpetuated by anatomical, biological, psychological and social factors. Chronic LBP should be managed with a holistic biopsychosocial approach of generally non-surgical measures. Spinal surgery has a role in alleviating radicular pain and disability resulting from neural compression, or where back pain relates to cancer, infection, or gross instability. Spinal surgery for all other forms of back pain is unsupported by clinical data, and the broader evidence base for spinal surgery in the management of LBP is poor and suggests it is ineffective. Emerging areas of interest include selection of a minority of patients who may benefit from surgery based on spinal sagittal alignment and/or nuclear medicine scans, but an evidence base is absent. Spinal surgery for back pain has increased substantially over recent decades, and disproportionately among privately insured patients, thus the contribution of industry and third-party payers to this increase, and their involvement in published research, requires careful consideration.

Comparison of value per operative time between anterior lumbar interbody fusion and lumbar disc arthroplasty: A propensity score-matched analysis

Context

Despite the growing evidence demonstrating its effectiveness, lumbar disc arthroplasty (LDA) rates have not increased significantly in recent years. A likely contributing factor is uncertainties related to reimbursement and insurers' denial of coverage due to fear of late complications, reoperations, and unknown secondary costs. However, no prior study has compared the physician reimbursement rates of lumbar fusion and LDA.

Aim

The aim of this study was to compare the relative value units (RVUs) per min as well as 30-day readmission, reoperation, and morbidity rates between anterior lumbar interbody fusion (ALIF) and LDA.

Settings and Design

This was a retrospective cohort study.

Subjects and Methods

The current study utilizes data obtained from the National Surgical Quality Improvement Program database. Patients who underwent ALIF or LDA between 2011 and 2019 were included in the study.

Statistical Analysis Used

Propensity score matching analysis was performed according to demographic characteristics and comorbidities. Matched groups were compared through Fisher's exact test and independent t-test for categorical and continuous variables, respectively.

Results

Five hundred and two patients who underwent ALIF were matched with 591 patients who underwent LDA. Mean RVUs per min was significantly higher for ALIF compared to LDA. ALIF was associated with a significantly higher 30-day morbidity rate compared to LDA, while readmission and reoperation rates were statistically similar. ALIF was also associated with higher frequencies of deep venous thrombosis (DVT) and blood transfusions.

Conclusions

ALIF is associated with significantly higher RVUs per min compared to LDA. ALIF is also associated with higher rates of 30-day morbidity, DVT, and blood transfusions, while readmission and reoperation rates were statistically similar.

In which cases do surgeons specializing in total disc replacement perform fusion in patients with symptomatic lumbar disc degeneration?

PURPOSE

The purpose of this study was to investigate reasons and their frequency for why spine surgeons subspecializing in total disc replacement (TDR) performed lumbar fusion rather than TDR.

METHODS

The study was based on a consecutive series of 515 patients undergoing lumbar TDR or fusion during a 5-year period by three surgeons specializing in TDR. For each fusion patient, the reason for not performing TDR was recorded.

RESULTS

TDR was performed in 65.4% (n = 337) of patients and the remaining 34.6% (n = 178) underwent anterior lumbar interbody fusion (ALIF ± posterior instrumentation). Of the 178 fusion patients, the most common reason for fusion was combined factors related to severe degenerative changes (n = 59, 11.5% of the study population). The second most common reason was > Grade 1 spondylolisthesis (n = 32, 6.2%), followed by insurance non-coverage (n = 24, 4.7%), and osteopenia/osteoporosis (n = 13, 2.5%). Fusion patients were significantly older than TDR patients (52.5 vs. 41.6 years; p < 0.01). There was no significant difference with respect to gender (41.2% female vs. 43.8% female, p > 0.05) or the percentage of patients with single-level surgery (61.2% vs. 56.7%, p > 0.05).

CONCLUSION

The most common reason for not performing lumbar TDR was related to anatomic factors that may compromise stability of the operated segment and/or TDR functionality. The older age of fusion patients may be related to these factors. This study found that many patients are appropriate candidates for lumbar TDR. However, even among TDR subspecialists, fusion is preferred when there are factors that cannot be addressed with TDR and/or may compromise implant functionality.

National trends in the utilization of lumbar disc replacement for lumbar degenerative disc disease over a 10-year period, 2010 to 2019

Background

Lumbar fusion (LF) is commonly performed to manage lumbar degenerative disc disease (LDDD) that has failed conservative measures. However, lumbar disc replacement (LDR) procedures are increasingly prevalent and designed to preserve motion in carefully selected patients.

Methods

A retrospective cohort study was performed using the National Inpatient Sample (NIS), queried from 2010 to 2019 to identify patients undergoing single and double-level LF or LDR with a diagnosis of LDDD using International Classification of Diseases (ICD) 9th (ICD-9) and 10th (ICD-10) revision diagnostic and procedure codes. Propensity score matching (PSM) with a ratio of 2:1 was performed. All cost estimates reflect reported hospital costs adjusted to December 2019 United States Dollars.

Results

A total of 1,129,121 LF cases (99.3%) and 8,049 LDR cases (0.7%) were identified, with 364,637 (32.3%) and 712 (8.8%) comprising two-level surgeries, respectively. 1,712 LDRs were performed in 2010 (1.27% of all), decreasing to 565 in 2013 (0.52%), and increased slightly to 870 in 2019 (0.74%). LDR patients were significantly more likely to be younger (mean age 41.2 vs. 57.1, P<0.001) and healthier (mean ECI 0.88 vs. 1.80, P<0.001). On matched analysis, LDR hospital costs were $4,529 less (P<0.001) and length of stay was 0.65 days shorter (P<0.001) than LF patients. LDR patients had lower rates of any complication (7.0% vs. 13.2%, P<0.001), neurologic complication (3.0% vs. 4.2%, P=0.006), and blood transfusion (3.1% vs. 8.1%, P<0.001) compared to LF patients.

Conclusions

The prevalence of LDR procedures decreased from 2010-2017 but began to increase again in 2018 and 2019. Single-level LDR was associated with reduced costs and length of stay (LOS), and lower rates of blood transfusion compared to LF in patients with LDDD.

Structural design and mechanical performance of composite vascular grafts

This study reviews the state of the art in structural design and the corresponding mechanical behaviours of composite vascular grafts. We critically analyse surface and matrix designs composed of layered, embedded, and hybrid structures along the radial and longitudinal directions; materials and manufacturing techniques, such as tissue engineering and the use of textiles or their combinations; and the corresponding mechanical behaviours of composite vascular grafts in terms of their physical–mechanical properties, especially their stress–strain relationships and elastic recovery. The role of computational studies is discussed with respect to optimizing the geometrics designs and the corresponding mechanical behaviours to satisfy specialized applications, such as those for the aorta and its subparts. Natural and synthetic endothelial materials yield improvements in the mechanical and biological compliance of composite graft surfaces with host arteries. Moreover, the diameter, wall thickness, stiffness, compliance, tensile strength, elasticity, and burst strength of the graft matrix are determined depending on the application and the patient. For composite vascular grafts, hybrid architectures are recommended featuring multiple layers, dimensions, and materials to achieve the desired optimal flexibility and function for complying with user-specific requirements. Rapidly emerging artificial intelligence and big data techniques for diagnostics and the three-dimensional (3D) manufacturing of vascular grafts will likely yield highly compliant, subject-specific, long-lasting, and economical vascular grafts in the near-future.

Graphic abstract

Single-Level Total Disc Replacement: Mid- to Long-Term Outcomes

BACKGROUND

Total disc replacement (TDR) has been shown to be effective for the treatment of lumbar degenerative disc disease (DDD) in carefully selected patients. Previous studies have demonstrated high rates of patient satisfaction and improvement in patient-reported outcome measures (PROMs) compared with preoperative status but most have short-term follow-up or small cohort sizes only.

OBJECTIVE

The aim of this study is to report mid- to long-term PROMs from the treatment of symptomatic single-level lumbar DDD with TDR.

METHODS

Data collected prospectively concerning single-level TDR performed via an anterior approach were included for analysis. A preoperative assessment was obtained followed by postoperative follow-up assessments at 3, 6, and 12 months, and yearly follow-up thereafter. PROMs included patient satisfaction, visual analog score back and leg, Oswestry Disability Index, and Roland-Morris Disability Questionnaire.

RESULTS

A total of 211 patients (118 men, 93 women) operated on between June 1997 and July 2015 were included in this study. Minimum follow-up was 4 years. The average age was 42.2 (range 24-87) years and median follow-up 96 interquartile range 72-132, range 48-120) months. The operative levels were L5-S1 (160, 75.8%) and L4-L5 (61, 24.2%). Both statistically and clinically significant improvements observed postoperatively were maintained at 10 years. In addition, 92% of patients reported either good (n = 29) or excellent satisfaction (n = 155) with treatment at final review.

CONCLUSIONS

This study shows that single-level lumbar TDR used appropriately in selected patient results in clinically significant improvements in pain and function, well above the minimum clinically important difference, and good to excellent satisfaction in most patients. Further study to define long-term outcomes and survivorship is required.

CLINICAL RELEVANCE

Statistically significant and clinically relevant improvements can be achieved by single-level lumbar TDR, in the treatment of single-level discogenic axial low back pain, with or without radiculopathy. These outcomes are sustained in the mid- to long-term followup periods.

LEVEL OF EVIDENCE: 4

Cervical and Lumbar Disc Arthroplasty: A Review of Current Implant Design and Outcomes

While spinal disc pathology has traditionally been treated using fusion-based procedures, recent interest in motion-preserving disc arthroplasties has grown. Traditional spinal fusion is associated with loss of motion, alteration of native spine kinematics, and increased risks of adjacent segment disease. The motion conferred by disc arthroplasty is believed to combat these complications. While the first implant designs resulted in poor patient outcomes, recent advances in implant design and technology have shown promising radiographic and clinical outcomes when compared with traditional fusion. These results have led to a rapid increase in the utilization of disc arthroplasty, with rates of cervical arthroplasty nearly tripling over the course of 7 years. The purpose of this review was to discuss the evolution of implant design, the current implant designs utilized, and their associated outcomes. Although disc arthroplasty shows significant promise in addressing some of the drawbacks associated with fusion, it is not without its own risks. Osteolysis, implant migration, and the development of heterotopic ossification have all been associated with disc arthroplasty. As interest in these procedures grows, so does the interest in developing improved implant designs aimed at decreasing these adverse outcomes. Though they are still relatively new, cervical and lumbar disc arthroplasty are likely to become foundational methodologies for the treatment of disc pathology.

An Artificial PVA-BC Composite That Mimics the Biomechanical Properties and Structure of a Natural Intervertebral Disc

Disc herniation is one of the most ubiquitous healthcare problems in modern cities—severe patients eventually require surgical intervention. However, the existing operations—spinal fusion and artificial disc replacement—alter the biomechanics of the spine, leaving much room for improvement. The appropriateness of polyvinyl alcohol (PVA) for biomedical applications has been recognised due to its high water content, excellent biocompatibility, and versatile mechanical properties. In this study, a newly-designed PVA–bacterial cellulose (PVA-BC) composite was assembled to mimic both the biomechanics and annular structure of natural intervertebral discs (IVDs). PVA-BC composites of various concentrations were fabricated and tested under unconfined compression and compressive creep in order to acquire the values of the normalised compressive stiffness and whole normalised deformation. The normalised compressive stiffness increased considerably with an increasing PVA concentration, spanning from 1.82 (±0.18) to 3.50 (±0.14) MPa, and the whole normalised deformation decreased from 0.25 to 0.13. Formulations of 40% PVA provided the most accurate mimicry of natural human IVDs in normalised whole deformation, and demonstrated higher dimensional stability. The biocompatible results further confirmed that the materials had excellent biocompatibility. The novel bionic structure and formulations of the PVA-BC materials mimicked the biomechanics and structure of natural IVDs, and ensured dimensional stability under prolonged compression, reducing the risk of impingement on the surrounding tissue. The PVA-BC composite is a promising material for third-generation artificial IVDs with integrated construction.

Lumbar Intervertebral Disc Herniation: Annular Closure Devices and Key Design Requirements

Lumbar disc herniation is one of the most common degenerative spinal conditions resulting in lower back pain and sciatica. Surgical treatment options include microdiscectomy, lumbar fusion, total disc replacement, and other minimally invasive approaches. At present, microdiscectomy procedures are the most used technique; however, the annulus fibrosus is left with a defect that without treatment may contribute to high reherniation rates and changes in the biomechanics of the lumbar spine. This paper aims to review current commercially available products that mechanically close the annulus including the AnchorKnot® suture-passing device and the Barricaid® annular closure device. Previous studies and reviews have focused mainly on a biomimetic biomaterials approach and have described some mechanical and biological requirements for an active annular repair/regeneration strategy but are still far away from clinical implementation. Therefore, in this paper we aim to create a design specification for a mechanical annular closure strategy by identifying the most important mechanical and biological design parameters, including consideration of material selection, preclinical testing requirements, and requirements for clinical implementation.

Electrostatic flocking of salt-treated microfibers and nanofiber yarns for regenerative engineering

Electrostatic flocking is a textile technology that employs a Coulombic driving force to launch short fibers from a charging source towards an adhesive-covered substrate, resulting in a dense array of aligned fibers perpendicular to the substrate. However, electrostatic flocking of insulative polymeric fibers remains a challenge due to their insufficient charge accumulation. We report a facile method to flock electrostatically insulative poly(ε-caprolactone) (PCL) microfibers (MFs) and electrospun PCL nanofiber yarns (NFYs) by incorporating NaCl during pre-flock processing. Both MF and NFY were evaluated for flock functionality, mechanical properties, and biological responses. To demonstrate this platform's diverse applications, standalone flocked NFY and MF scaffolds were synthesized and evaluated as scaffold for cell growth. Employing the same methodology, scaffolds made from poly(glycolide-co-_l-lactide) (PGLA) (90:10) MFs were evaluated for their wound healing capacity in a diabetic mouse model. Further, a flock-reinforced polydimethylsiloxane (PDMS) disc was fabricated to create an anisotropic artificial vertebral disc (AVD) replacement potentially used as a treatment for lumbar degenerative disc disease. Overall, a salt-based flocking method is described with MFs and NFYs, with wound healing and AVD repair applications presented.

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NaCl coatings enable sufficient charge accumulation on electrically insulative polymer fibers during electrostatic flocking.

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Flocked nanofiber yarns allow further functionalization of flocked scaffolds.

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Flocked fiber scaffolds sustain cell proliferation.

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Flocked PGLA (90:10) fiber scaffolds promote modest fiber-density dependent wound healing and angiogenesis.

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Flock fibers-reinforced elastomeric artificial vertebral discs are mechanically robust.

3D Bioprinted Implants for Cartilage Repair in Intervertebral Discs and Knee Menisci

Cartilage defects pose a significant clinical challenge as they can lead to joint pain, swelling and stiffness, which reduces mobility and function thereby significantly affecting the quality of life of patients. More than 250,000 cartilage repair surgeries are performed in the United States every year. The current gold standard is the treatment of focal cartilage defects and bone damage with nonflexible metal or plastic prosthetics. However, these prosthetics are often made from hard and stiff materials that limits mobility and flexibility, and results in leaching of metal particles into the body, degeneration of adjacent soft bone tissues and possible failure of the implant with time. As a result, the patients may require revision surgeries to replace the worn implants or adjacent vertebrae. More recently, autograft - and allograft-based repair strategies have been studied, however these too are limited by donor site morbidity and the limited availability of tissues for surgery. There has been increasing interest in the past two decades in the area of cartilage tissue engineering where methods like 3D bioprinting may be implemented to generate functional constructs using a combination of cells, growth factors (GF) and biocompatible materials. 3D bioprinting allows for the modulation of mechanical properties of the developed constructs to maintain the required flexibility following implantation while also providing the stiffness needed to support body weight. In this review, we will provide a comprehensive overview of current advances in 3D bioprinting for cartilage tissue engineering for knee menisci and intervertebral disc repair. We will also discuss promising medical-grade materials and techniques that can be used for printing, and the future outlook of this emerging field.

A guide to assessing post-operative complications following en bloc spinal resection

En-bloc resection of spinal tumours is a complex procedure with significant morbidity and mortality. The extensive resection leaves a large soft tissue and osseous defect requiring reconstruction. Following en-bloc resection, there may be complications relating to both the removal of the tumour and the subsequent reconstruction. This paper outlines the imaging appearances of the frequently encountered complications in our experience. The primary aim is to improve the confidence of the radiologist when reporting imaging following spinal en-bloc resection, however we believe this is also useful for the spinal and orthopaedic surgeons in assessing the patients following en block resection.

Lumbar Total Disc Replacement: Current Usage

Low back pain is the leading cause of disability worldwide in industrialized nations. The pathology underlying chronic low back pain is associated with numerous factors. Lumbar degenerative disc disease is a potential major source of low back pain. There are numerous treatment modalities and options. Nonsurgical treatment options exist in the form of pain management through a combination of anti-inflammatory medications and steroid injections, physical therapy and lifestyle modifications. This article reviews the history and current trends in use for lumbar toral disc arthroplasty for degenerative disc disease treatment. Furthermore, indications, contraindications, and complications management are discussed.

Risk factors for reoperation after lumbar total disc replacement at short-, mid-, and long-term follow-up

BACKGROUND CONTEXT

The reoperation rate following TDR (Total Disc replacement) has been established at short- and mid-term time points through the Food and Drug Administration Investigational Device Exemption (FDA IDE) trials. However, these trials include highly selected centers and surgeons with strict governance of indications. The utilization of TDR throughout the community needs further analysis.

PURPOSE

To identify the risk factors for lumbar spine reoperation in patients undergoing lumbar total disc replacement (TDR) at short-, mid-, and long-term follow-up.

STUDY DESIGN/SETTING

This study is a multi-center retrospective cohort study utilizing the New York Statewide Planning and Research Cooperative System database.

PATIENT SAMPLE

We identified 1,368 patients who underwent an elective primary lumbar TDR in New York State between January 1, 2005 and September 30, 2013.

OUTCOME MEASURES

The primary functional outcome of interest was lumbar reoperation, specifically the evaluation of independent risk factors for lumbar reoperation at a minimum of 2 years, with sub-analyses performed at 5 and ten years.

METHODS

International Classification of Diseases, Ninth revision codes were utilized to identify patients undergoing a primary lumbar TDR. We excluded patients with primary/revision lumbar fusion procedures and revision disc replacement procedures. Hospital academic status was determined by the Accreditation Council for Graduate Medical Education. Unique encrypted patient identifiers allowed for longitudinal follow-up for reoperation. Logistic regression models compared reoperation and no-reoperation cohorts, and were performed on sub-analyses for significant univariate predictors of reoperation.

RESULTS

Between January 2005 and September 2013, 1368 patients underwent a primary lumbar TDR. Reoperation occurred in 8.8% by 2 years, 15.8% by 5 years, and 19.5% by ten years. Diabetics were more likely to have reoperations (7.5% vs 3.8%, p=.013). Teaching hospitals experienced a decreased reoperation rate compared to nonteaching hospitals at 2-year (5.0% vs 10.5%, p=.002), 5-year (10.7% vs 17.9%, p=.002) and 10-year (11.7% vs 21.9%, p=.045) follow-up. Lumbar fusion was the most common reoperation (14.2%).

CONCLUSION

We identified an 8.8% reoperation rate after inpatient lumbar TDR at 2-years, 15.8% at 5-years, and 19.5% at 10-years. When stratifying by teaching status, reoperation rates at teaching centers align with those reported in FDA IDE studies. Diabetes was the only patient factor influencing reoperation rate. There is a growing consensus that lumbar TDR is a durable and appropriate surgical option for lumbar degenerative disc disease. Proper indications are crucial to obtaining good outcomes with lumbar TDR.

A novel lumbar total joint replacement may be an improvement over fusion for degenerative lumbar conditions: a comparative analysis of patient-reported outcomes at one year

BACKGROUND CONTEXT

Effective alternatives to lumbar fusion for degenerative conditions have remained elusive. Anterior total disc replacement does not address facet pathology or central/recess stenosis, resulting in limited indications. A posterior-based motion-preserving option that allows for neural decompression, facetectomy, and reconstruction of the disc and facets may have a role.

PURPOSE

The purpose was to compare one-year patient-reported outcomes for a novel, all-posterior, lumbar total joint replacement (LTJR - replacing both the disc and facet joints) against transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar conditions warranting fusion (degenerative spondylolisthesis, recurrent disc herniation, severe foraminal stenosis requiring facet removal, and adjacent segment degeneration).

STUDY DESIGN/SETTING

A retrospective analysis of prospectively collected data comparing outcomes for LTJR patients to TLIF patients at an academic teaching hospital.

PATIENT SAMPLE

Analysis was conducted on 156 adult TLIF patients who were propensity matched to the 52 LTJR patients for a total sample of 208.

OUTCOME MEASURES

Self-reported Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) for back and leg pain were compared preoperatively, 3 months and 1 year after surgery.

METHODS

The implant is a motion-preserving lumbar reconstruction that replaces the function of both the disc and facets and is implanted using a bilateral transforaminal approach with complete facetectomies. Adult patients with degenerative lumbar pathology undergoing either LTJR or open TLIF were analyzed. These degenerative conditions included: grade 1 degenerative spondylolisthesis, recurrent disc herniation, adjacent segment disease, disc degeneration with severe foraminal stenosis). Trauma, tumor, grade 2 or higher spondylolisthesis, spinal deformity, and infection cases were excluded. Propensity score matching was performed to ensure parity between the cohorts. Multivariable regression analyses were done to compare the 1-year results as measured by 3 different standards to assess procedure success.

RESULTS

At 3 months, both the LTJR and TLIF cohorts showed significant and similar improvements in ODI and NRS back and leg pain. At 1 year, the LTJR cohort showed continued improvement in ODI and NRS back pain, while the TLIF group showed a plateau for ODI, back and leg pain. In a series of three multivariable logistic regressions, LTJR was shown to provide 3.3 times greater odds of achieving the minimal clinical symptom state in disability and pain (ODI <20%, NRS back and leg pain <2) and 2.4 and 4.1 times greater odds of achieving substantial clinical benefit (18% reduction in ODI) and minimal clinically important difference (30% reduction in ODI) as compared to TLIF.

CONCLUSIONS

Here we present a comparative analysis for the first 52 patients undergoing a novel, posterior-based LTJR for the lumbar spine versus TLIF for degenerative pathology. The approach for the LTJR allows for wide neural decompression, facetectomy, and complete discectomy, with the implant working to replace the function of the disc and facets to preserve motion. At 1 year, the LTJR cohort showed significant improvement in ODI and NRS back and leg pain as compared to TLIF. These results suggest that wide neural decompression combined with motion preservation using this novel LTJR may represent a viable alternative to TLIF for treating certain degenerative conditions. A prospective controlled trial is under development to further evaluate the efficacy, safety, and durability of this procedure.

Facet Arthropathy Following Disc Replacement Versus Rehabilitation: A Prospective Study With 8-Year Follow-Up

STUDY DESIGN

A prospective study of patients originally randomized to total disc replacement (TDR) or multidisciplinary rehabilitation.

OBJECTIVE

To assess the long-term development of facet arthropathy (FA) after TDR versus nonoperative treatment, and to analyze the association between FA and clinical outcome.

SUMMARY OF BACKGROUND DATA

FA may appear or increase following TDR, but the natural course of FA is unclear, and no previous study has evaluated the long-term development of FA following TDR compared with nonoperative treatment.

METHODS

The study included 126 patients with chronic low back pain and degenerative changes in the lumbar intervertebral discs. The patients underwent pretreatment and 8-year follow-up magnetic resonance imaging (MRI) and 8-year follow-up computed tomography (CT) of the lumbar spine. The primary outcome measure was FA development (yes/no) on MRI at index level L4/L5 or L5/S1, defined as increased FA grade value from pretreatment to follow-up according to Weishaupt grading system. Secondary outcomes included the association between FA (on MRI and CT) and Oswestry Disability Index (ODI) or back pain as well as reoperations.

RESULTS

Increased index level FA grade was more frequent after TDR versus nonoperative treatment (36%, 25/69 vs. 2%, 1/57 of patients, P < 0.001), but was not related to change in ODI or back pain. At follow-up, index level FA grades were higher after TDR versus nonoperative treatment (odds ratio 4.0 MRI and 5.9 CT), but were not related to ODI less than or equal to 22. Four patients (6%) treated with TDR and no patients treated nonoperatively were operated for lateral recess stenosis with posterior decompression at the index level during follow-up.

CONCLUSION

Index level FA development was more likely after TDR compared with nonoperative treatment but was not associated with the 8-year clinical outcome. Index level FA may have contributed to reoperations in the TDR group.

LEVEL OF EVIDENCE

2.

Top 100 Cited Articles on Spinal Disc Arthroplasty Research

STUDY DESIGN

A bibliometric review of current literature.

OBJECTIVE

The purpose of this study was to identify and analyze the 100 most cited articles in spinal disc arthroplasty (SDA) research.

SUMMARY OF BACKGROUND DATA

In the last several decades, SDA has been widely performed all over the world, with increasing popularity of cervical disc arthroplasty (CDA). While there is a large number of articles on this topic, to our knowledge, there is no bibliometric analysis yet.

METHODS

All databases from the Web of Science were searched in a three-step approach. The information of the 100 most cited studies was collected, including title, first and last author, year of publication, journal, total citations, geographic origin, subspecialty, and types of artificial intervertebral disc for further analysis.

RESULTS

The 100 most-cited articles were published from 1966 to 2015 in 9 different journals and were cited from 66 to 346 times. A total of 11 countries contributed to the 100 articles and the United States topped the list, with 54 articles, followed by Germany and France, with 10 and nine articles, respectively. There were more studies in CDA (n = 53) than lumbar disc arthroplasty (n = 35). Most of the studies reported clinical and radiographic outcomes (n = 33). The most productive periods were from 2006 to 2010. The majority of publications were in Spine, which published 43 articles. In total, 12 authors published more than two articles on the list.

CONCLUSION

Of the top 100 most cited articles on SDA, cervical papers outnumbered lumbar articles and the United States had 55 articles, with no other countries having more than 10. Our paper can help readers determine which of the thousands of articles on this topic are the most impactful and important ones to be familiar with.

LEVEL OF EVIDENCE

3.

NF-κB inhibitor, NEMO-binding domain peptide attenuates intervertebral disc degeneration

BACKGROUND CONTEXT

Nonphysiological mechanical loading and inflammation are both critically involved in intervertebral disc (IVD) degeneration, which is characterized by an increase in cytokines and matrix metalloproteases (MMPs) in the nucleus pulposus (NP). This process is known to be mediated by the NF-κB pathway.

CLINICAL SIGNIFICANCE

Current clinical treatments for IVD degeneration focus on the alleviation of symptoms rather than targeting the underlying mechanism. Injection of an NF-κB inhibitor may attenuate the progression of IVD degeneration.

PURPOSE

To investigate the ability of the NF-κB inhibitor, NEMO binding domain peptide (NBD), to alter IVD degeneration processes by reducing IL-1β- and mechanically-induced cytokine and MMP levels in human nucleus pulposus cells in vitro, and by attenuating IVD degeneration in an in vivo rat model for disc degeneration.

STUDY DESIGN

Experimental in vitro and animal model.

PATIENT SAMPLE

Discarded specimens of lumbar disc from 21 patients, and 12 Sprague Dawley rats.

OUTCOME MEASURES

Gene and protein expression, cell viability, µMRI and histology.

METHODS

IL-1β-prestimulated human nucleus pulposus cells embedded into fibrin constructs were loaded in the Flexcell FX-5000 compression system at 5 kPa and 1 Hz for 48 hours in the presence and absence of NBD. Unloaded hNPC/fibrin constructs served as controls. Cell viability in loaded and unloaded constructs was quantified, and gene and protein expression levels determined. For in vivo testing, a rat needle disc puncture model was employed. Experimental groups included injured discs with and without NBD injection and uninjured controls. Levels of disc degeneration were determined via µMRI, qPCR and histology. Funding sources include $48,874 NASS Young Investigator Research Grant and $119,174 NIH 5K01AR071512-02. There were no applicable financial relationships or conflicts of interest.

RESULTS

Mechanical compression of hNPC/fibrin constructs resulted in upregulation of MMP-3 and IL-8. Supplementation of media with 10 μM NBD during loading increased cell viability, and decreased MMP-3 gene and protein levels. IVD injury in rat resulted in an increase in MMP-3, IL-1β and IL-6 gene expression. Injections of 250 µg of NBD during disc injury resulted in decreased IL-6 gene expression. µMRI analysis demonstrated a reduction of disc hydration in response to disc needle injury, which was attenuated in NBD-treated IVDs. Histological evaluation showed NP and AF lesion in injured discs, which was attenuated by NBD injection.

CONCLUSIONS

The results of this study show NBD peptide's capacity to reduce IL-1β- and loading-induced MMP-3 levels in hNPC/fibrin constructs while increasing the cells' viability, and to attenuate IVD degeneration in rat, involving downregulation of IL-6. Therefore, NBD may be a potential therapeutic agent to treat IVD degeneration.

Spine Fixation Hardware: An Update

OBJECTIVE. The purpose of this article is to provide a review of the imaging of spine fixation hardware. CONCLUSION. As the prevalence of neck and back pain continues to increase, so does the number of surgical procedures used to treat such pain. Accordingly, new techniques and hardware designs are used, and the hardware will be seen on postoperative imaging. It is critical that radiologists understand the appropriate imaging modalities for the assessment of spine fixation hardware, recognize the normal imaging appearance of such hardware, and be able to detect hardware-related complications.

Postoperative Spinal CT: What the Radiologist Needs to Know

During the past 2 decades, the number of spinal surgeries performed annually has been steadily increasing, and these procedures are being accompanied by a growing number of postoperative imaging studies to interpret. CT is accurate for identifying the location and integrity of implants, assessing the success of decompression and intervertebral arthrodesis procedures, and detecting and characterizing related complications. Although postoperative spinal CT is often limited owing to artifacts caused by metallic implants, parameter optimization and advanced metal artifact reduction techniques, including iterative reconstruction and monoenergetic extrapolation methods, can be used to reduce metal artifact severity and improve image quality substantially. Commonly used and recently available spinal implants and prostheses include screws and wires, static and extendable rods, bone grafts and biologic materials, interbody cages, and intervertebral disk prostheses. CT assessment and the spectrum of complications that can occur after spinal surgery and intervertebral arthroplasty include those related to the position and integrity of implants and prostheses, adjacent segment degeneration, collections, fistulas, pseudomeningoceles, cerebrospinal fluid leaks, and surgical site infections. Knowledge of the numerous spinal surgery techniques and devices aids in differentiating expected postoperative findings from complications. The various types of spinal surgery instrumentation and commonly used spinal implants are reviewed. The authors also describe and illustrate normal postoperative spine findings, signs of successful surgery, and the broad spectrum of postoperative complications that can aid radiologists in generating reports that address issues that the surgeon needs to know for optimal patient management.^©RSNA, 2019.

[A review on the current state of ball-on-socket type artificial lumbar disc prosthesis]

Total lumbar disc replacement is an alternative to interbody fusion for the effective treatment of symptomatic degenerative disc disease. This paper reviewed the history of ball-on-socket type artificial lumbar disc (ALD) prosthesis, which is a typical ALD prosthesis and summarized the ALD prosthesis research progress, according to different materials such as metal-on-metal, metal-on-polymer, and polymer-on-polymer prosthesis. The structural design factors of ball-on-socket type ALD prosthesis were analyzed and its prospect of development was also presented. The purpose of this paper is to provide a theoretical reference for the design of the ball-on-socket ALD prosthesis by reviewing the current state of ball-on-socket type ALD prosthesis.

Multiobjective Design Optimization of a Biconcave Mobile-Bearing Lumbar Total Artificial Disk Considering Spinal Kinematics, Facet Joint Loading, and Metal-on-Polyethylene Contact Mechanics

Total disk arthroplasty (TDA) using an artificial disk (AD) is an attractive surgical technique for the treatment of spinal disorders, since it can maintain or restore spinal motion (unlike interbody fusion). However, adverse surgical outcomes of contemporary lumbar TDAs have been reported. We previously proposed a new mobile-bearing AD design concept featuring a biconcave ultrahigh-molecular-weight polyethylene (UHMWPE) mobile core. The objective of this study was to develop an artificial neural network (NN) based multiobjective optimization framework to refine the biconcave-core AD design considering multiple TDA performance metrics, simultaneously. We hypothesized that there is a tradeoff relationship between the performance metrics in terms of range of motion (ROM), facet joint force (FJF), and polyethylene contact pressure (PCP). By searching the resulting three-dimensional (3D) Pareto frontier after multiobjective optimization, it was found that there was a "best-tradeoff" AD design, which could balance all the three metrics, without excessively sacrificing each metric. However, for each single-objective optimum AD design, only one metric was optimal, and distinct sacrifices were observed in the other two metrics. For a commercially available biconvex-core AD design, the metrics were even worse than the poorest outcomes of the single-objective optimum AD designs. Therefore, multiobjective design optimization could be useful for achieving native lumbar segment biomechanics and minimal PCPs, as well as for improving the existing lumbar motion-preserving surgical treatments.

A Dynamic Radiographic Imaging Study of Lumbar Intervertebral Disc Morphometry and Deformation In Vivo

Intervertebral discs are important structural components of the spine but also are significant sources of morbidity, especially for the “low back” lumbar region. Mechanical damage to, or degeneration of, the lumbar discs can diminish their structural integrity and elicit debilitating low back pain. Advancement of reparative or regenerative means to treat damaged or degenerated discs is hindered by a lack of basic understanding of the disc load-deformation characteristics in vivo. The current study presents an in vivo analysis of the morphometry and deformation of lumbar (L2-S1) intervertebral discs in 10 healthy participants while performing a common lifting act, using novel dynamic radiographic imaging of the lumbar vertebral body motion. Data analyses show uniquely different (p < 0.05) characteristics in morphometry, normal and shear strain patterns of the L5S1 discs, while the rest of lumbar discs exhibit great similarity. In particular shear strains in L2-L5 discs exhibited stronger linear correlations (R² ≥ 0.80) between strain changes and amount of lumbar flexion-extension motion compared to L5S1 (R² ≤ 0.5). The study therefore advances the state of knowledge on in vivo mechanical responses of the lumbar intervertebral discs during functional tasks.

Artificial disc replacement in spine surgery

Total disc replacement (TDR) is an innovative procedure that has gained traction in spine surgery. A large amount of data in the literature report on the short-term outcomes of TDR surgery favorably. However, surgeons remain reluctant to opt for TDR surgery due to uncertainty of long-term outcomes. Recently, long term data regarding TDR surgery has become available, with some studies showing superior outcomes to fusion surgery. The goal of this review is to synthesize and clinically contextualize the recent literature on TDR surgery. This article also provides brief discussion of the biggest challenges currently facing disc arthroplasties and the ways in which they are being tackled.

Spondylodiscitis due to Cutibacterium acnes following lumbosacral intradiscal biologic therapy: a case report

A 40-year-old woman with a history of chronic low back pain underwent a fluoroscopically guided intradiscal platelet-rich plasma injection (PRP) at the L5-S1 level. She subsequently developed progressive low back pain, night sweats and decreased ability to ambulate. Laboratory work-up revealed elevated acute phase reactants and imaging revealed L5-S1 intervertebral disc and vertebral end-plate abnormalities highly suggestive of spondylodiscitis. Computed tomography-guided aspiration and biopsy cultures grew Cutibacterium acnes and the patient was subsequently treated with intravenous antibiotics without surgical management. To the best of our knowledge, this is the first published case of lumbar spondylodiscitis following an intradiscal PRP injection, and brings to the forefront several clinically relevant issues including the antimicrobial effects of PRP, the role of C. acnes in spine infections and the ideal treatment protocol for intradiscal biologics in order to minimize morbidity and optimize functional outcomes.

The Influence of Conflicts of Interest on Outcomes in the Lumbar Disc Arthroplasty Literature: A Systematic Review

STUDY DESIGN

A systematic review.

OBJECTIVE

The aim of this study was to determine the association between study outcomes and the presence of a conflict of interest (COI) in the lumbar disc arthroplasty (LDA) literature.

SUMMARY OF BACKGROUND DATA

Previous studies have evaluated the efficacy of LDA as a surgical alternative to arthrodesis. As investigators may have financial relationships with LDA device companies, it is important to consider the role of COI on study outcomes.

METHODS

A systematic review was performed to identify articles reporting clinical outcomes of LDA. Any financial COIs disclosed were recorded and confirmed through Open Payments and ProPublica databases. Study outcomes were graded as favorable, unfavorable, or equivocal. Pearson Chi-squared analysis was used to determine an association between COI and study outcomes. Favorable outcomes were tested for an association with study characteristics using Poisson regression with robust error variance.

RESULTS

Fifty-seven articles were included, 30 had a financial COI, while 27 did not. Ninety percent of the conflicted studies disclosed their COI in the article. Studies with United States authors were more likely to be conflicted (P = 0.019). A majority of studies reported favorable outcomes for LDA (n = 39). Conflicted studies were more likely to report favorable outcomes than nonconflicted studies (P = 0.020). Articles with COIs related to consultant fees (P = 0.003), research funding (P = 0.002), and stock ownership (P < 0.001) were more likely to report favorable outcomes.

CONCLUSION

This study highlights the importance for authors to accurately report conflicting relationships with industry. As such, orthopedic surgeons should critically evaluate study outcomes with regard to potential conflicts before recommending LDA as a surgical option to their patients.

LEVEL OF EVIDENCE

3.

Development of a Biconcave Mobile-Bearing Lumbar Total Disc Arthroplasty Concept Using Finite Element Analysis and Design Optimization

Total disc arthroplasty (TDA) is a motion-preserving surgical treatment for spinal disorders. However, adverse surgical outcomes, such as abnormal kinematics, facet joint (FJ) overloading, and polyethylene (PE) failures, have limited wide application of lumbar TDAs. The objectives of this computational study were to elucidate how implant design and FJ articulation both influence metal-on-polyethylene (MoP) motion and contact mechanics, as well as to propose and refine a new mobile-bearing TDA concept which enhanced postoperative performance. Simulation results show that abnormal motions (lift-off and/or unsymmetrical motion) are alleviated in fixed-/mobile-bearing TDA-treated segments, as the FJ gap increases. It clearly demonstrates that FJ articulation guides segmental motion and interferes with intended MoP articulation. For an existing biconvex mobile-bearing design, component impingement leads to a peak PE stress of 20.8 MPa (yield stress: 13 MPa), indicating a high risk of PE creep/fracture. Therefore, we proposed a new TDA concept featuring a biconcave PE core with a smooth shape, in order to strengthen the PE rim and mitigate edge-loading. Furthermore, the biconcave-core TDA was optimally designed to promote normal segmental range of motion (ROM), or to minimize polyethylene contact pressure (PCP). In extension (the severest loading scenario), the biconvex-core TDA design caused a ROM 3.6° (+88%) greater than the intact segment and a peak PCP of 116.5 MPa. In contrast, ROM-optimal or PCP-optimal biconcave-core TDA designs decreased the ROM difference to 0.0° or the peak PCP to 24.3 MPa. Therefore, this new TDA design can potentially reduce the incidence of hypermotion and PE damage. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1805-1816, 2019.

Design and material evaluation for a novel lumbar disc replacement implanted via unilateral transforaminal approach

The degeneration of the intervertebral disc is one of the principal causes of low back pain. Total disc replacement is a surgical treatment that aims to replace the degenerated disc with a dynamic implant to restore spine biomechanics. This paper proposes the first design of an elastomeric lumbar disc replacement that is implanted as a pair of devices via unilateral transforaminal surgical approach. Furthermore, several biomaterials (Polyurethanes (PU) and Polycarbonate Urethanes (PCU)) are evaluated for the purpose of the implant to mimic the axial compliance of the spine. Bionate II 80A (a pure PCU), Elast Eon 82A E5-325 (a PU with polydimethylsiloxane and polyhexamethylene oxide), Chronosil (a PCU based silicone elastomer) 80A with 5% and 10% of silicone were obtained and injection moulded according to the shape of the implant core, which was defined after a stress distribution analysis with the finite element method. The dimensions for each specimen were: 14.6 × 5.6 × 6.1 mm (length, width and height). Quasistatic compression tests were performed at a displacement rate of 0.02 mm/s. The obtained stiffness for each material at 1 mm displacement was: Bionate II 80A, 448.48 N/mm; Elast Eon 82A E5-325, 216.55 N/mm; Chronosil 80A 5%, 127.73 N/mm; and Chronosil 80A 10%, 126.48 N/mm. Dimensional changes were quantified after two quasi-static compression tests. Plastic deformation was perceived in all cases with a total percentage of height loss of: 4.1 ± 0.5% for Elast Eon 82A E5-325; 3.2 ± 0.5% for Chronosil 80A 10%; 2.7 ± 0.3% for Chronosil 80A 5% and 1.1 ± 0.2% for Bionate II 80A. The mechanical behaviour of these biomaterials is discussed to assess their suitability for the novel disc replacement device proposed.

Mid- to long-term results of total disc replacement for lumbar degenerative disc disease: a systematic review

Background

Lumbar total disc replacement (TDR) has shown satisfactory clinical outcomes with few complications and reoperations at short-term follow-up, but the mid- to long-term results are not clear.

Purpose

The objective of this study was to evaluate the mid- to long-term clinical outcomes of artificial TDR for lumbar degenerative disc diseases.

Patients and methods

A systematic search was conducted using the PubMed database to identify studies of TDR surgery that included at least 3 years of follow-up. The search keywords were as follows: lumbar, total disc replacement, and arthroplasty. The following data were extracted: patient demographics, visual analogue scale (VAS) and Oswestry disability index (ODI) scores, satisfactory rate, clinical success rate, complications, and reoperations.

Results

Thirteen studies, including eight prospective studies and five retrospective studies, met the criteria. A total of 946 patients were identified who reported at least 3 years of follow-up results. The artificial prostheses in these studies were ProDisc-L, Charité, AcroFlex, Maverick, and XL TDR. Patients with lumbar TDR demonstrated significant improvements in VAS scores of 51.1 to 70.5% and of − 15.6 to − 44.4 for Oswestry disability index (ODI) scores at the last follow-up. Patient satisfaction rates were reported in eight studies and ranged from 75.5 to 93.3%. Complication rates were reported in 11 studies, ranging from 0 to 34.4%. The overall reoperation rate was 12.1% (119/986), ranging from 0 to 39.3%, with eight of the 13 studies reporting a reoperation rate of less than 10%.

Conclusions

This review shows that lumbar TDR effectively results in pain relief and an improvement in quality of life at mid- to long-term follow-up. Complication and reoperation rates were acceptable. However, this study did not provide sufficient evidence to show that lumbar TDR is superior to fusion surgery. To answer that question, a greater number of high-quality randomized controlled trials (RCTs) are needed.

We Need to Talk about Lumbar Total Disc Replacement

BACKGROUND

Replacement of a diseased lumbar intervertebral disc with an artificial device, a procedure known as lumbar total disc replacement (LTDR), has been practiced since the 1980s.

METHODS

Comprehensive review of published literature germane to LTDR, but comment is restricted to high-quality evidence reporting implantation of lumbar artificial discs that have been commercially available for at least 15 years at the time of writing and which continue to be commercially available.

RESULTS

LTDR is shown to be a noninferior (and sometimes superior) alternative to lumbar fusion in patients with discogenic low back pain and/or radicular pain attributable to lumbar disc degenerative disease (LDDD). Further, LTDR is a motion-preserving procedure, and evidence is emerging that it may also result in risk reduction for subsequent development and/or progression of adjacent segment disease.

CONCLUSIONS

In spite of the substantial logistical challenges to the safe introduction of LTDR to a health care facility, the procedure continues to gain acceptance, albeit slowly.

CLINICAL RELEVANCE

Patients with LDDD who are considering an offer of spinal surgery can only provide valid and informed consent if they have been made aware of all reasonable surgical and nonsurgical options that may benefit them. Accordingly, and in those cases in which LTDR may have a role to play, patients under consideration for other forms of spinal surgery should be informed that this valid procedure exists.

DISC REPLACEMENT IN LUMBAR SPINE

ABSTRACT With the increase in the elderly population worldwide, the prevalence of degenerative diseases tends to grow, especially degenerative disc disease (DDD) in the lumbar spine. It is important to seek excellence treatments to ensure a better quality of life for patients. In this sense, the total disc replacement and the use of prostheses in the lumbar spine have been pointed out as alternative and promising treatments when compared to the standard treatment. The aim of this study is to show the results of total replacement of the intervertebral disc, through a review of the literature. The electronic search was performed in the PubMed databases, with the keywords “Total Disk Replacement”, “Low Back Pain”, and “Arthroplasty” in articles published as of 2012. We selected 16 articles. Level of Evidence: II. Type of study: Systematic reviewb of Level II studies or Level I studies with inconsistent results.

Lumbar Disk Arthroplasty for Degenerative Disk Disease: Literature Review

Low back pain is the principal cause of long-term disability worldwide. We intend to address one of its main causes, degenerative disk disease, a spinal condition involving degradation of an intervertebral disk. Following unsuccessful conservative treatment, patients may be recommended for surgery. The two main surgical treatments for lumbar degenerative disk disease are lumbar fusion: traditional standard surgical treatment and lumbar disk arthroplasty, also known as lumbar total disk replacement. Lumbar fusion aims to relieve pain by fusing vertebrae together to eliminate movement at the joint, but it has been criticized for problems involving insignificant pain relief, a reduced range of motion, and an increased risk of adjacent segment degeneration. This leads to development of the lumbar total disk replacement technique, which aims to relieve pain replacing a degenerated intervertebral disk with a moveable prosthesis, thus mimicking the functional anatomy and biomechanics of a native intervertebral disk. Over the years a large range of prosthetic disks has been developed. The efficacy and current evidence for these prostheses are discussed in this review. The results of this study are intended to guide clinical practice and future lumbar total disk replacement device choice and design.