Clinical results of total lumbar disc replacement with ProDisc II: three-year results for different indications

Clinical and Radiological Outcomes of Cervical Disc Arthroplasty in Patients with Modic Change

OBJECTIVE

Modic change (MC) is defined as abnormalities observed in the intervertebral disc subchondral and adjacent vertebral endplate subchondral bone changes. Most studies on MC were reported in the lumbar spine and associated with lower back pain. However, MC has been rarely reported in the cervical spine, let alone in those who underwent cervical disc replacement (CDR). This study aimed to focus on MC in the cervical spine and reveal clinical and radiological parameters, especially heterotopic ossification (HO), for patients who underwent CDR. Furthermore, we illustrated the association between MC and HO.

METHODS

We retrospectively reviewed patients who underwent CDA from January 2008 to December 2019. The Japanese Orthopaedic Association (JOA), Neck Disability Index (NDI), and Visual Analog Scale (VAS) scores were used to evaluate the clinical outcomes. Radiological evaluations were used to conclude the cervical alignment (CL) and range of motion (ROM) of C2-7, functional spinal unit angle (FSUA), shell angle (SA), FSU height, and HO. Univariate and multivariate logistic regressions were performed to identify the risk factors for HO. The Kaplan-Meier (K-M) method was used to analyze potential risk factors, and multivariate Cox regression was used to identify independent risk factors.

RESULTS

A total of 139 patients were evaluated, with a mean follow-up time of 46.53 ± 26.60 months. Forty-nine patients were assigned to the MC group and 90 to the non-MC group. The incidence of MC was 35.3%, with type 2 being the most common. Clinical outcomes (JOA, NDI, VAS) showed no significant difference between the two groups. The differences in C2-7 ROM between the two groups were not significant, while the differences in SA ROM and FSUA ROM were significantly higher in the non-MC than in the MC group (p < 0.05). Besides, FSU height in MC group was significantly lower than that in non-MC group. Parameters concerning CL, including C2-7, FSUA, SA, were not significantly different between the two groups. The incidence of HO and high-grade HO, respectively, in the MC group was 83.7% and 30.6%, while that in the non-MC group was 53.3% and 2.2%, and such differences were significant (p < 0.05). Multivariate logistic regression analyses and Cox regression showed that MC and involved level were significantly associated with HO occurrence (p < 0.05). No implant migration and secondary surgery were observed.

CONCLUSION

MC mainly affected the incidence of HO. Preoperative MC was significantly associated with HO formation after CDR and should be identified as a potential risk factor for HO. Rigorous criteria for MC should be taken into consideration when selecting appropriate candidates for CDR.

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.

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.

A comparative finite element analysis of artificial intervertebral disc replacement and pedicle screw fixation of the lumbar spine

Titanium alloy-based Pedicle screw-rod fusion is a very common technique to provide higher fusion regularity than other methods. In recent times, Carbon-fibre-reinforced (CFR)-PEEK rod is used to better reduce the fusion rate. Alternatively, total disc replacement (TDR) is also very common for the non-fusion treatment method for degenerative disc disease (DDD). This study aims to investigate flexibility (ROM), stability, stress condition in implant, implant adjacent bone of the implanted lumbar spine during different physiological movements and loading environments. The finite element (FE) intact model of the lumbar spine (L2-L5) with two-level pedicle screw-rod fusion at L3-L4-L5 and two-level artificial disc replacement was developed. CFR-PEEK was taken for rod for semi-rigid fusion. UHMWPE was taken as core part of the artificial disc. The FE models were simulated under 6, 8 and 10 Nm moments in left right lateral bending, flexion and extension movements. The total ROM was reduced for two-level pedicle screw fixation and increased for the artificial disc replacement model during flexion extension compared to the intact spine. The total ROM was reduced by around 54% and 25% for two-level fixation and increased by 30% and 19.5% for artificial disc replacement spine, under flexion-extension and left-right lateral bending respectively. For screw fixation, the ROM increased by 15% and 18% reduced by 4.5% and 14% for disc replacement at the adjacent segments for flexion-extension and left-right lateral bending.

Lumbar Arthroplasty: Past, Present, and Future

Lumbar degenerative disc disease is a pathologic process that affects a large portion of our aging population. In the recent past, surgical treatment has involved fusion procedures. However, lumbar disc arthroplasty and replacement provides an alternative for carefully selected patients. It provides the major advantage of motion preservation and thus keeps adjacent segments from significantly progressive degeneration. The history of lumbar disc replacement has roots that start in the 1960s with the implantation of stainless-steel balls. Decades later, multiple implants with different material design and biomechanical properties were introduced to the market. New third-generation implants have made great strides in improved biomechanics and clinical outcomes. Although there is room for further advancement and studies are warranted to assess the long-term durability and sustainability of lumbar disc arthroplasty, it has certainly proven to be a very acceptable alternative within the surgical armamentarium that should be offered to patients who meet indications. In this review we present an overview of lumbar disc arthroplasty including its history, indications, biomechanics, challenges, and future directions.

J, Li Z, Ou Y. The short-term efficacy and safety of artificial total disc replacement for selected patients with lumbar degenerative disc disease compared with anterior lumbar interbody fusion: A systematic review and meta-analysis

Purpose

To systematically compare the efficacy and safety of lumbar total disc replacement (TDR) with the efficacy and safety of anterior lumbar interbody fusion (ALIF) for the treatment of lumbar degenerative disc disease (LDDD).

Methods

The electronic databases PubMed, Web of Science and the Cochrane Library were searched for the period from the establishment of the databases to March 2018. The peer-reviewed articles that investigate the safety and efficacy of TDR and ALIF were retrieved under the given search terms. Quality assessment must be done independently by two authors according to each item of criterion. The statistical analyses were performed using RevMan (version 5.3) and Stata (version 14.0). The random-effect model was carried out to pool the data. The I² statistic was used to evaluate heterogeneity. The sensitivity analysis was carried out to assess the robustness of the results of meta-analyses by omitting the articles one by one.

Results

Six studies (5 randomized controlled trials (RCT) and 1 observational study) involving 1093 patients were included in this meta-analysis. The risk of bias of the studies could be considered as low to moderate. Operative time (MD = 4.95; 95% CI -18.91–28.81; P = 0.68), intraoperative blood loss (MD = 4.95; 95% CI -18.91–28.81; P = 0.68), hospital stay (MD = -0.33; 95% CI, -0.67–0.01; P = 0.05), complications (RR = 0.96; 95% CI 0.91–1.02; P = 0.18) and re-operation rate (RR = 0.54; 95% CI 0.14–2.12; P = 0.38) were without significant clinical difference between groups. Patients in the TDR group had higher postoperative satisfaction (RR = 1.19; 95% CI 1.07–1.32; P = 0.001) and, better improvements in ODI (MD = -10.99; 95% CI -21.50- -0.48; P = 0.04), VAS (MD = -10.56; 95% CI -19.99- -1.13; P = 0.03) and postoperative lumbar mobility than did patients in the ALIF group.

Conclusions

The results showed that TDR has significant superiority in term of reduced clinical symptoms, improved physical function and preserved range of motion for the treatment of LDDD compared to ALIF. TDR may be an ideal alternative for the selected patients with LDDD in the short-term. However, the results of this study cannot suggest the use of TDR instead of ALIF in lumbar spine treatment only in the light of short term results. More studies that are well-designed, that are of high-quality and that have larger samples are needed to further evaluate the efficacy and safety of TDR with at the long-term follow-up.

Level of evidence

Therapeutic Level 3

Comparison of Treatment Outcomes in Nonspecific Low-Back Pain Patients With and Without Modic Changes Who Receive Chiropractic Treatment

OBJECTIVE

The aim of this study was to determine if there was a difference in outcomes in patients with nonspecific low back pain, both with and without Modic changes (MCs), who received chiropractic care.

METHODS

This prospective outcomes study included 112 patients with low back pain without disc herniation on magnetic resonance imaging. All patients were treated with spinal manipulative therapy. At baseline, the numerical rating scale (NRS) and Bournemouth Questionnaire (BQ) for disability were collected. The NRS, BQ, and Patient's Global Impression of Change (primary outcome) were collected at the follow-up time points of 1 week, 1 month, and 3 months to assess overall improvement. Magnetic resonance imaging scans were analyzed for the presence of MCs and, if present, classified as Modic I or II. The χ² test was used to compare the proportion of patients reporting clinically relevant "improvement" between patients with and without MCs and between Modic I and Modic II patients. The unpaired Student t test was used to compare NRS and BQ at baseline and change scores at all follow-up time points.

RESULTS

For the primary outcome measure, the proportion of patients reporting relevant "improvement" (Patient's Global Impression of Change), and for the secondary outcome measures (NRS and BQ change scores), there were no significant differences between Modic positive and Modic negative patients or between Modic I and Modic II patients.

CONCLUSION

Neither the presence nor absence of MCs nor the Modic change category were related to treatment outcomes for patients with low back pain without disc herniation who received chiropractic care.

Comparison of Lumbar Total Disc Replacement With Surgical Spinal Fusion for the Treatment of Single-Level Degenerative Disc Disease: A Meta-Analysis of 5-Year Outcomes From Randomized Controlled Trials

STUDY DESIGN

Meta-analysis.

OBJECTIVES

To evaluate the long-term efficacy and safety of total disc replacement (TDR) compared with fusion in patients with functionally disabling chronic low back pain due to single-level lumbar degenerative disc disease (DDD) at 5 years.

METHODS

PubMed and Cochrane Central Register of Controlled Trials databases were searched for randomized controlled trials reporting outcomes at 5 years for TDR compared with fusion in patients with single-level lumbar DDD. Outcomes included Oswestry Disability Index (ODI) success, back pain scores, reoperations, and patient satisfaction. All analyses were conducted using a random-effects model; analyses were reported as relative risk (RR) ratios and mean differences (MDs). Sensitivity analyses were conducted for different outcome definitions, high loss to follow-up, and high heterogeneity.

RESULTS

The meta-analysis included 4 studies. TDR patients had a significantly greater likelihood of ODI success (RR 1.0912; 95% CI 1.0004, 1.1903) and patient satisfaction (RR 1.13; 95% CI 1.03, 1.24) and a significantly lower risk of reoperation (RR 0.52; 95% CI 0.35, 0.77) than fusion patients. There was no association with improvement in back pain scores whether patients received TDR or fusion (MD -2.79; 95% CI -8.09, 2.51). Most results were robust to sensitivity analyses. Results for ODI success and patient satisfaction were sensitive to different outcome definitions but remained in favor of TDR.

CONCLUSIONS

TDR is an effective alternative to fusion for lumbar DDD. It offers several clinical advantages over the longer term that can benefit the patient and reduce health care burden, without additional safety consequences.

Time Course of Radiologic Changes After Lumbar Total Disc Replacement: Experience of Single Institute With Minimum 5-Year Follow-up

STUDY DESIGN

This was a retrospective observatory analysis study.

OBJECTIVE

The purpose of this study was to evaluate long-term safety and therapeutic effectiveness of the lumbar total disc replacement (TDR) using ProDisc-L by analyzing the radiologic changes at the index and adjacent levels in minimum 5-year follow-up.

SUMMARY OF BACKGROUND DATA

Early successful clinical results of lumbar TDR have been reported. However, few reports have published its therapeutic effectiveness and radiologic degenerative changes at the index and adjacent segments in the long term.

MATERIALS AND METHODS

Forty-three patients were followed-up for at least 60 months. Radiologic changes were assessed by segmental range of motion (ROM) at the index and adjacent levels, global lumbar lordosis, and disc space height (DSH). The magnetic resonance imaging and computed tomographic scans were used to determine the facet arthrosis and intervertebral disc degeneration at the index and adjacent levels.

RESULTS

Gradual decrements of DSH restoration were observed until the last follow-up. Mean global and segmental ROM of index segments were significantly reduced (P=0.044, 0.00) at the last visit. There were 21 patients (48.8%) with no motion at index segment (ROM<0.5 degrees) at the last visit. Among the 56 segments operated on, progression of facet arthrosis was observed in 30.3% of index segments and 10.9% of adjacent segments. None of the postoperative radiologic parameters included in the present study presented significant correlation with clinical outcome.

CONCLUSIONS

The study demonstrates that only half of the lumbar TDR patients can maintain segmental motion at the index level >5-year after surgery and TDR provides a good clinical outcome postoperatively regardless of motion preservation or DSH height preservation at the last follow-up. After TDR, the degenerative changes in the index and adjacent segments advanced as compared with our previous report of 2-year follow-up, however, these changes did not appear to exert negative influence upon clinical outcomes.

National Trends for Primary and Revision Lumbar Disc Arthroplasty Throughout the United States

STUDY DESIGN

Retrospective database study.

OBJECTIVES

Analysis of economic and demographic data concerning lumbar disc arthroplasty (LDA) throughout the United States to improve value-based care and health care utilization.

METHODS

The National Inpatient Sample database was queried for patients who underwent primary or revision LDA between 2005 and 2013. Demographic and economic data included total surgeries, costs, length of stay, and frequency of routine discharge. The National Inpatient Sample database represents a 20% sample of discharges from US hospitals weighted to provide national estimates.

RESULTS

Primary LDA decreased 86% from 3059 to 420 from 2005 to 2013. The mean total cost of LDA increased 33% from $17 747 to $23 804. The mean length of stay decreased from 2.8 to 2.4 days. The mean routine discharge (home discharge without visiting nursing care) remained constant at 91%. Revision procedures (removal, supplemental fixation, or reoperation at the treated level) declined 30% from 194 to 135 cases over the study period. The mean revision burden, defined as the ratio of revision procedures to the sum of primary and revision procedures, was 12% (range 6% to 24%). The mean total cost of revisions ranged from $12 752 to $22 282.

CONCLUSIONS

From 2005 to 2013, primary LDA significantly declined in the United States by 86% despite several studies pointing to improved efficacy and cost-efficiency. This disparity may be related to a lack of surgeon reimbursement from insurance companies. Congruently, the number of revision LDA cases has declined 30%, while revision burden has risen from 6% to 24%.

Total Disc Replacement Versus Anterior-Posterior Interbody Fusion in the Lumbar Spine and Lumbosacral Junction: A Cost Analysis

STUDY DESIGN

Prospective observational cohort study.

OBJECTIVES

To analyze clinical and economic results in patients with degenerative disc disease in the lumbar area for patients who received combined anterior and posterior fusion or total disc replacement (TDR).

METHODS

The study included 75 patients, 38 in the fusion group and 37 in the TDR group, who received either anterior/posterior fusion or TDR for lumbar disc disease from January 2005 to December 2008 with a minimum follow-up of 24 months. We collected data with regard to clinical parameters, demographics, visual analogue scale scores, Oswestry Disability Index scores, SF-36 and SF-6D data, surgery time, amount of blood loss, transfusion of blood products, number of levels, duration of hospital stay, and complications. For cost analysis, general infrastructure, theatre costs, as well as implant costs were examined, leading to primary hospital costs. Furthermore, average revision costs were examined, based on the actual data. Statistical analysis was performed using t tests for normal contribution and Mann-Whitney test for skew distributed values. The significance level was set to .05.

RESULTS

There was a higher surgery time, more blood loss, and longer hospital stay for the fusion group, compared with the TDR group. In addition, the hospital costs for the primary procedure and revision were 35% higher in the fusion group. The clinical data in terms of SF-36 and SF-6D showed no difference between these 2 groups.

CONCLUSIONS

TDR is a good alternative to anterior and posterior lumbar fusion in terms of short follow-up analysis for clinical data and cost analysis. General advice cannot be given due to missing data for long-term costs in terms of surgical treatment of adjacent level or further fusion techniques.

Motion preservation following total lumbar disc replacement at the lumbosacral junction: a prospective long-term clinical and radiographic investigation

BACKGROUND CONTEXT

Total lumbar disc replacement (TDR) intends to avoid fusion-related negative side effects by means of motion preservation. Despite their widespread use, the adequate quality and quantity of motion, as well as the correlation between radiographic data with the patient's clinical symptomatology, remains to be established. Long-term data are lacking in particular.

PURPOSE

This study aimed to perform a clinical and radiographic long-term investigation following TDR with special emphasis on motion preservation assessment and to establish any potential correlation with patient-reported outcome parameters.

STUDY DESIGN/SETTING

A prospective, single-center, clinical, and radiological investigation following TDR with ProDisc II (Synthes, Paoli, PA, USA) was carried out.

PATIENT SAMPLE

Patients with a minimum 5-year follow-up (FU) after TDR performed for the treatment of intractable and predominant (≥80%) axial low back pain resulting from single-level degenerative disc disease without instabilities or deformities at the lumbosacral junction (L5-S1) comprised the sample.

OUTCOME MEASURES

Visual analogue scale (VAS), Oswestry Disability Index (ODI), and patient satisfaction rates (three-scale outcome rating), range of motion (ROM) at the index- and cranially adjacent level as well as segmental lumbar lordosis (SLL) and global lumbar lordosis (GLL) were the outcome measures.

METHODS

All data were acquired within the framework of an ongoing prospective clinical trial. Patients were examined preoperatively, 3, 6, and 12 months postoperatively, and annually thereafter. X-rays were performed in antero-posterior and lateral views as well as functional flexion/extension images. Radiological examinations included ROM at the index and cranially adjacent level as well as SLL and GLL. X-ray measurements were correlated with the clinical outcome parameters. A longitudinal analysis was performed between baseline data with those from the early (3-6 months), mid- (12-24 months), and late FU stages (≥5 years).

RESULTS

Results from 51 patients with a mean FU of 7.8 years (range 5.0-13.3 years) were available for the final analysis. X-ray measurements revealed a maintained mobility with a trend toward gradually declining ROM values. Although no statistically significant difference in ROM was detected between the preoperative and early FU (6.8° vs. 5.8°, p=.1), a further reduction in ROM became statistically significant at the mid- and final FU, with mean ROM of 5.2° and 4.4°, respectively (p<.001). Global lumbar lordosis increased from 48.8° to 54.4° (p<.0001) which was attributed to a lordotic shift from 18.2° to 28.0° at the index segment (p<.00001) and which was positively correlated with the applied implant lordosis (p<.05). A compensatory reduction of lordosis was observed at the cranially adjacent segment (p<.0001). The mobility of the cranially adjacent level remained unchanged (p>.05). The clinical outcome scores (VAS, ODI) revealed a significant improvement from baseline levels (p<.05). The reduction in ROM was not negatively correlated with the patient's clinical symptomatology (p>.05).

CONCLUSION

The present data reveal an increased GLL resulting from a lordotic shift of the index segment, which was strongly correlated with the applied implant lordosis. This lordotic shift was accompanied by a compensatory reduction of lordosis at the cranially adjacent segment. A gradual and statistically significant decline of the device mobility was noted over time which, however, did not negatively impact the patient's clinical symptomatology. Although the present long-term investigation provides additional insight into longitudinal radiographic changes and their influence on the patient's clinical symptomatology following TDR, the adequate quality and quantity of motion with artificial motion-preserving implants remains to be established, which will aid in defining more refined treatment concepts for both fusion and motion preserving techniques alike.

RESULTS OF TOTAL LUMBAR INTERVERTEBRAL DISK REPLACEMENT WITH M6-L: A MULTICENTER STUDY

ABSTRACT Objective: In this paper we report the clinical and radiological results of lumbar intervertebral disk (IVD) replacement with M6-L for the treatment of patients with IVD degeneration. Methods: One hundred and fifty-six patients with IVD degeneration were operated with the one level implantation of an M6-L prosthesis at three neurosurgical departments, in Irkutsk, Krasnoyarsk and Vladivostok. We assessed pain intensity (VAS), the Oswestry disability index (ODI) and outcomes by the Macnab scale up to 36 months after surgery. Instrumental data were used to assess range of motion in the operated segment and heterotopic ossification by the McAfee-Suchomel classification. Results: The average VAS before surgery was 6.9 ± 1.6 cm. After surgery, this value reduced significantly, to an average of 1.3 ± 1.2 cm (p<0.001). The average ODI before surgery was 40.2 ± 6.9%, and after IVD arthroplasty, this indictor improved to 12.3 ± 6.1% (p <0.001). Range of motion in the operated segment at baseline averaged 36.8 ± 2.6o, and within 36 months after the operation, this had increased to 41.2 ± 2.9o. During the entire follow-up period, signs of severe (13.4%, n = 21) or moderate (10.2%, n = 16) heterotopic ossification were observed. Conclusions: The use of M6-L prosthesis can significantly reduce the level of pain, improve quality of life and maintain the physiological range of motion in the operated spinal segment in patients with degenerative lesions IVD at a low level of adverse outcomes. [249 Words].

Spinal motion preservation surgery: indications and applications

Fusion is one of the most commonly performed spinal procedures, indicated for a wide range of spinal problems. Elimination of motion though results in accelerated degeneration of the adjacent level, known as adjacent level disease. Motion preservation surgical methods were developed in order to overcome this complication. These methods include total disc replacement, laminoplasty, interspinous implants and dynamic posterior stabilization systems. The initial enthusiasm about these methods was followed by certain concerns about their clinical usefulness and their results. The main indications for total disc replacement are degenerative disc disease, but the numerous contraindications for this method make it difficult to find the right candidate. Application of interspinous implants has shown good results in patients with spinal stenosis, but a more precise definition is needed regarding the severity of spinal stenosis up to which these implants can be used. Laminoplasty has several advantages and less complications compared to fusion and laminectomy in patients with cervical myelopathy/radiculopathy. Dynamic posterior stabilization could replace conventional fusion in certain cases, but also in this case the results are successful only in mild to moderate cases.

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.

Lumbar total disc arthroplasty: outdated surgery or here to stay procedure? A systematic review of current literature

Background

The purpose of this study was to summarize the available evidence about total lumbar disc replacement (TDR), focusing our attention on four main topics: clinical and functional outcomes, comparison with fusion surgery results, rate of complications and influence on sagittal balance.

Materials and methods

We systematically searched Pubmed, Embase, Medline, Medscape, Google Scholar and Cochrane library databases in order to answer our four main research questions. Effective data were extracted after the assessment of methodological quality of the trials.

Results

Fifty-nine pertinent papers were included. Clinical and functional scores show statistically significant improvements, and they last at all time points compared to baseline. The majority of the articles show there is no significant difference between TDR groups and fusion groups. The literature shows similar rates of complications between the two surgical procedures.

Conclusions

TDR showed significant safety and efficacy, comparable to lumbar fusion. The major advantages of a lumbar TDR over fusion include maintenance of segmental motion and the restoration of the disc height, allowing patients to find their own spinal balance. Disc arthroplasty could be a reliable option in the treatment of degenerative disc disease in years to come.

Level of evidence

II.

The usefulness of radiological grading scales to predict pain intensity, functional impairment, and health-related quality of life after surgery for lumbar degenerative disc disease

PURPOSE

The goal of this study is to determine the relationship of radiological grading scales of lumbar degenerative disc disease (DDD) with postoperative pain intensity, functional impairment, and health-related quality of life (HRQoL).

METHODS

Response to surgical treatment at 6 weeks (W6) on the visual analogue scale (VAS) for back and leg pain, Oswestry-Disability (ODI) and Roland-Morris Disability Index (RMDI), Timed Up and Go (TUG) test, EuroQol (EQ) 5D, and Short-Form Health-Survey (SF-12) physical component summary (PCS) was compared between patients with different Modic (MOD) and Pfirrmann (PFI) grades. Longitudinal outcomes at day 3 (D3), W6, 6 months (M6), and 1 year (Y1) were compared.

RESULTS

The study included 338 patients (mean age, 58.6 years), of which n = 202 (59.8%) had MOD 1-3 and n = 217 (64.2%) PFI 4-5 changes. Patients with MOD 1-3 were as likely as patients without MOD changes to be treatment-responders at W6 in terms of VAS leg pain, ODI, RMDI, TUG, EQ5D, and SF-12 PCS. Similarly, patients with PFI 4-5 were as likely as patients with PFI 1-3 changes to be treatment-responders at W6. Longitudinal outcomes were similar at D3, W6, M6, and Y1 between patients with and without MOD changes. Patients with PFI 4-5 fared similar to those with PFI 1-3 except for inferior HRQoL on the SF-12 PCS metric at Y1.

CONCLUSIONS

There was no distinct relationship between commonly used radiological grading scales of lumbar DDD with clinical outcome. Therefore, no prognosis should be made on the grounds of preoperative PFI and MOD classifications for patients undergoing spine surgery for lumbar DDD.

Does the type of sagittal spinal shape influence the clinical results of lumbar disc arthroplasty?

INTRODUCTION

It has been suggested that the indication for lumbar total disc replacement (LTDR) takes into account the local parameters, such as the type of disc disease demonstrated on MRI and the presence or absence of facet joint osteoarthritis. The type of preoperative sagittal curvature could also be taken into account. This study reports the clinical results of LTDRs depending on the type of sagittal spinal alignment.

MATERIAL AND METHODS

Eighty patients were included in this prospective study, with a mean age of 41.7years (range, 27-56years). The clinical analysis took into account the lumbar VAS, the Oswestry Disability Index (ODI), and the preoperative frequency of painkiller use, at 1year and at the last follow-up. The satisfaction index, return to work, and willingness to undergo the same treatment were also collected. The radiological study included the analysis of lumbar-pelvic parameters to distribute the patients according to the Roussouly classification.

RESULTS

The mean follow-up was 59.1months (range, 14-96months). The type 1 group included four cases. Reduction of the VAS, the ODI score, and the frequency of painkiller use at the last follow-up were significant in type 2 and 3 patients, and non-significant for type 4. Eighty-five percent of type 2 patients and 87.5% of type 3 patients were satisfied or very satisfied with the surgery versus only 68% of the type 4 patients. In addition, 63% of the type 4 patients declared they would be willing to undergo the same treatment again versus 85% of the type 2 patients and 82.5% of the type 3 patients. It should also be noted that 67% of the patients in this series returned to work.

DISCUSSION AND CONCLUSION

This study underscores the influence of the type of sagittal curvature on the clinical results of LTDR, with type 4 patients showing inferior clinical results because of a higher rate of residual lower back pain. The indication in LTDR should be reconsidered for discogenic lower back pain in type 4 patients.

Long-Term Outcomes Following Lumbar Total Disc Replacement Using ProDisc-II: Average 10-Year Follow-Up at a Single Institute

STUDY DESIGN

A retrospective analysis.

OBJECTIVE

To evaluate the long-term clinical and radiographic outcomes and to investigate who achieved the successful outcomes after lumbar total disc replacement (TDR) using ProDisc II.

SUMMARY OF BACKGROUND DATA

There are few evidences regarding the long-term efficacy and safety of TDR. Furthermore, it has not been addressed which patients achieved good outcomes in long-term follow-up.

METHODS

Data at 1-, 2-, 5-, 7-year, and last follow-up were used for the analysis. According to the presence of combined pathologies, patients were categorized as groups A and B (presumed good and bad candidates, respectively). Clinical outcomes were evaluated using visual analog scale, Oswestry Disability Index, clinical success rate, and subjective satisfaction (four-point scale). Radiographic results included segmental range of motion.

RESULTS

Total study population was 54 patients with 69 segments with the average follow-up duration of 120.0 months. There were 39 patients in group A and 15 in group B. Visual analog scale and Oswestry Disability Index scores were improved significantly at all follow-up periods, reaching maximal improvement at the postoperative 2 years. Clinical success rate and satisfaction rate were significantly higher in group A (76.9% and 87.2%, respectively) than those in group B (40.0% and 60.0%, respectively) at the last follow-up. Five patients (9.3%) required revision fusion surgeries, and they are all in group B. The final segmental range of motion was well maintained in monosegmental TDR, but not in bisegmental TDR.

CONCLUSION

Lumbar TDR using Prodisc II showed the successful outcomes with the clinical success rate of 76.9% and the satisfaction rate of 87.2% when the patients were presumed as good candidate for TDR. However, the patients who had the combined pathologies showed suboptimal results with high risk of the revision surgeries. Thus, the strict patient selection process is mandatory for the successful outcomes.

LEVEL OF EVIDENCE

4.

Prospective Clinical and Radiographic Results of Activ L Total Disk Replacement at 1- to 3-Year Follow-up

STUDY DESIGN

A prospective clinical study.

OBJECTIVE

To assess the clinical and radiographic results of activ L total disk replacement (TDR) on degenerative disk diseases.

SUMMARY OF BACKGROUND DATA

There are few reports on Activ L TDR, and this is the first in China.

MATERIALS AND METHODS

From March 2009 to March 2012, 32 patients with degenerative disk disease underwent either monosegmental or bisegmental lumbar TDR, which was documented in a prospective observational mode. Clinical success was defined as disability [Oswestry Disability Index (ODI)] improvement of at least 15 points versus baseline, no device failure, no major complications, no neurological deterioration. Additional clinical parameters as Visual Analogue Scale and Oswestry Disability Index (ODI) were evaluated preoperatively and postoperatively (1, 2, and 3 y). Radiographic parameters as range of motion (ROM) and intervertebral disk height (IDH) of the index and adjacent segments were also carried out. Prosthesis subsidence and heterotopic ossification were observed during the follow-up period. Work status was tracked for all patients.

RESULTS

Overall, 30 patients (93.7%) were available for a mean follow-up of 28.8 months (12-46 mo) and had complete radiographic data. Their mean age was 45.1 years (32-58 y). At 3 years postoperatively, the success rate was 86.7% (26/30). After surgery, clinical parameters as Visual Analogue Scale score for back and leg pain, and ODI score showed statistically significant improvement (P<0.001), and the situation was well maintained during the follow-up time points. At 3 years postoperatively, the mean IDH at the index segment and upper and lower adjacent segments were 12.87, 12.61, and 11.62 mm, respectively, showing no significant difference compared with preoperative data (P1=0.0597, P2=0.6669, P3=0.9813). The ROM of the index and upper adjacent segment showed a slight but significant increase at the 3-year follow-up compared with baseline (P1=0.0128, P2=0.0007). The changes of ROM at the lower adjacent segment were not significant (P=0.6637). Tears of the iliac vein were observed in 2 patients. Prosthesis subsidence was observed in 3 patients (1 at 12 mo postoperatively, 1 at 24 mo postoperatively, and 1 at 32 mo postoperatively). Heterotopic ossification was observed in 1 patient at 36 mo postoperatively. At the 3-year follow-up, only 8 patients went back to their original work, and 15 patients changed jobs, whereas the last 7 patients stopped working.

CONCLUSIONS

The 1- to 3-year follow-up of this cohort of patients showed satisfactory clinical outcomes. The IDHs at index and adjacent segments were well maintained after the surgery. The ROM at the lower adjacent segment remained unchanged, but the ROM at the index and upper adjacent segments showed a slight increase. The long-term results of activ L TDR was to be investigated.

Maverick total disc replacement in a real-world patient population: a prospective, multicentre, observational study

PURPOSE

Controlled trials have shown that total disc replacement (TDR) can provide pain and disability relief to patients with degenerative disc disease; however, whether these outcomes can also be achieved for patients treated in normal surgical practice has not been well documented.

METHODS

This prospective, international study observed changes in disability and back pain in 134 patients who were implanted with Maverick TDR within the framework of routine clinical practice and followed for 2 years post-surgery. Primary and secondary outcomes were the differences from baseline to 6 months post-surgery in the means of the Oswestry Disability Index and the change in back pain intensity assessed on a 10-cm visual analogue scale, respectively. Mean patient age at surgery was 43 years, but ranged up to 65 years.

RESULTS

One hundred twenty-three patients had an implant at one level, 10 patients at two levels, and one patient at three levels. Statistically significant improvements in mean disability (-25.4) and low back pain intensity (-4.0) scores were observed at 6 months postoperatively (P < 0.0001 for both) in the hands of experienced surgeons (>10 TDRs per centre). During the study, 56 patients (42 %) experienced a complication or adverse event.

CONCLUSIONS

This is the first international observational study to report outcomes of TDR in real-world clinical settings. We showed statistically significant improvements in disability and pain scores at 6 months following Maverick TDR, which were maintained for 2 years alongside an acceptable rate of perioperative complications. The safety and tolerability shown in this observational study were comparable to those from controlled trials.

Comparison of Single-Level and Multiple-Level Outcomes of Total Disc Arthroplasty: 24-Month Results

BACKGROUND

Low back pain is one of the most prevalent problems in industrialized countries, affecting as many as 80% of all adults at some time in their lives. Among the significant contributors to low back pain is degenerative disc disease (DDD). Although fusion has been well accepted for treatment of DDD, high rates of complications and stress to adjacent segments remain a concern. Lumbar total disc replacement (TDR) was developed with a goal of preserving motion and avoiding various fusion-related complications, but the relative merits of single vs. multiple level arthroplasty remain unclear.

METHODS

This is a multi-center, single arm, prospective post-market registry of the M6-L, consisting of consecutive patients presenting with lumbar DDD who agreed to participate. This paper reports on those patients who have completed at least 24 months of followup to date. Clinical outcome measures include the Oswestry Disability Index (ODI) and back and leg Visual Analogue Scales (VAS). Radiographic analysis of disc angle and range of motion (ROM) was also performed.

RESULTS

Results for 83 patients comprising 121 implants in two cohorts (49 single level (SL), 34 multiple levels (ML)) are reported. Both cohorts experienced significant improvement at 24 months including significant decreases in ODI and VAS. Relative to SL procedures, ML procedures demonstrated either comparable results, or results that trended favorably towards the ML procedures. Index and global ROM at 24 months were not significantly different between the two cohorts, while the disc angles were larger in the SL cohort regardless of index level.

CONCLUSIONS

This is the first study to report clinical and radiographic outcomes of TDR with the M6-L in SL vs ML procedures with two years of followup. The results suggest initial device safety and effectiveness when used for the treatment of lumbar degenerative disc disease at one or more levels.

Does heterotopic ossification affect the outcomes of cervical total disc replacement? A meta-analysis

STUDY DESIGN

Meta-analysis.

OBJECTIVE

The purpose of this study was to answer the following questions: (1) Does heterotopic ossification (HO) negatively influence clinical outcomes after cervical total disc replacement (CTDR)? (2) Should patients be classified into HO and non-HO groups? (3) Is there a more rational classification?

SUMMARY OF BACKGROUND DATA

Heterotopic ossification has emerged as a common complication after CTDR and has been an important reason for reoperation, thus limiting the use of the surgery. However, the influence of HO on clinical outcomes after CTDR has not been well established.

METHODS

A meta-analysis was conducted with studies identified by searches of MEDLINE, EMBASE, and the Cochrane Library. We calculated the weighted mean differences of the visual analogue scale pain score, Neck Disability Index, and range of motion (ROM). Patients were classified into 2 groups under 3 classifications on the basis of the grade of HO. Results were pooled using a fixed effect model or a random effects model, according to the heterogeneity.

RESULTS

There were significant differences in ROM under all 3 classifications. The visual analogue scale pain score and the Neck Disability Index between the patients with and without HO showed no significant difference after CTDR. Significant differences in visual analogue scale pain score were observed when patients were classified into a "high-grade HO" group (McAfee grades 3 or 4 HO) and a "low-grade HO" group (McAfee grade 0, 1, or 2 HO).

CONCLUSIONS

The presence of HO is not associated with clinical outcomes after CTDR. However, the severity of HO actually impacts clinical outcomes in an inverse manner, which needs further investigation. It is inappropriate to classify patients on the basis of the presence of HO; further studies of the classifications (ROM-affecting HO vs. ROM-preserving HO; high-grade HO vs. low-grade HO) and cervical stability after CTDR are needed.

LEVEL OF EVIDENCE

2.

ISASS Policy Statement - Lumbar Artificial Disc

PURPOSE

The primary goal of this Policy Statement is to educate patients, physicians, medical providers, reviewers, adjustors, case managers, insurers, and all others involved or affected by insurance coverage decisions regarding lumbar disc replacement surgery.

PROCEDURES

This Policy Statement was developed by a panel of physicians selected by the Board of Directors of ISASS for their expertise and experience with lumbar TDR. The panel's recommendation was entirely based on the best evidence-based scientific research available regarding the safety and effectiveness of lumbar TDR.

A study on the cervical spondylotic myelopathy treated by anterior cervical diskectomy and fusion in accordance with Modic changes with a 2-year minimum follow-up

BACKGROUND

The aim of this research is to analyze the influence of Modic types on the clinical results of cervical spondylotic myelopathy treated by anterior cervical diskectomy and fusion.

METHODS

A total of 106 patients with a mean age of 55.8 ± 6.5 years were included in this study. Patients with Modic changes were retrospectively reviewed. In this study, 23 patients were classified as Modic-1, 39 patients were classified as Modic-2, and 44 patients were classified as Modic-0. Clinical evaluations were performed preoperatively and repeated at 3, 6, 12, and 24 months after operation.

RESULTS

In this study, all patients were followed up for a mean period of 30.2 months (range, from 24 to 36 months). Significant clinical improvement (P < 0.05) was observed in Japanese Orthopaedic Association (JOA) score and axial symptoms between the preoperative evaluation and the final follow-up. Comparing the result of mean JOA score after anterior cervical diskectomy and fusion (ACDF) in the Modic-1 group and other groups, statistically significant differences could be found at 12 months after surgery (P < 0.05). Comparing the outcome visual analog scale (VAS) of axial symptoms among different groups after ACDF, patients with Modic-1 changes showed significantly lower VAS of axial symptoms postoperatively (P < 0.05).

CONCLUSION

After anterior cervical diskectomy and fusion, both Modic-1 and Modic-2 groups showed excellent clinical outcomes over a 2-year follow-up. Better clinical results were achieved in patients with Modic-1 changes compared to the group of patients with Modic-2 and Modic-0 changes on magnetic resonance images.

Indications for lumbar total disc replacement: selecting the right patient with the right indication for the right total disc

Summary of Background Data

As with any surgery, care should be taken to determine patient selection criteria for lumbar TDR based on safety and optimizing outcome. These goals may initially be addressed by analyzing biomechanical implant function and early clinical experience, ongoing evaluation is needed to refine indications.

Objective

The purpose of this work was to synthesize information published on general indications for lumbar TDR. A secondary objective was to determine if indications vary for different TDR designs.

Methods

A comprehensive literature search was conducted to identify lumbar TDR articles. Articles were reviewed and patient selection criteria and indications were synthesized.

Results

With respect to safety, there was good agreement in the literature to exclude patients with osteopenia/osteoporosis or fracture. Risk of injury to vascular structures due to the anterior approach was often addressed by excluding patients with previous abdominal surgery in the area of disc pathology or increased age. The literature was very consistent on the primary indication for TDR being painful disc degeneration unresponsive to at least 6 months of nonoperative care. Literature investigating the impact of previous spine surgery was mixed; however, prior surgery was not necessarily a contra-indication, provided the patient otherwise met selection criteria. The literature was mixed on setting a minimum preoperative disc height as a selection criterion. There were no publications investigating whether some patients are better/worse candidates for specific TDR designs. Based on the literature a proposal for patient selection criteria is offered.

Conclusions

Several TDR indications and contra-indications are widely accepted. No literature addresses particular TDR design being preferable for some patients. As with any spine surgery, ongoing evaluation of TDR outcomes will likely lead to more detailed general and device design specific indications.

Mid- to long-term results of total lumbar disc replacement: a prospective analysis with 5- to 10-year follow-up

BACKGROUND CONTEXT

The role of fusion of lumbar motion segments for the treatment of intractable low back pain (LBP) from degenerative disc disease (DDD) without deformities or instabilities remains controversially debated. Total lumbar disc replacement (TDR) has been used as an alternative in a highly selected patient cohort. However, the amount of long-term follow-up (FU) data on TDR is limited. In the United States, insurers have refused to reimburse surgeons for TDRs for fear of delayed complications, revisions, and unknown secondary costs, leading to a drastic decline in TDR numbers.

PURPOSE

To assess the mid- and long-term clinical efficacy as well as patient safety of TDR in terms of perioperative complication and reoperation rates.

STUDY DESIGN/SETTING

Prospective, single-center clinical investigation of TDR with ProDisc II (Synthes, Paoli, PA, USA) for the treatment of LBP from lumbar DDD that has proven unresponsive to conservative therapy.

PATIENT SAMPLE

Patients with a minimum of 5-year FU after TDR, performed for the treatment of intractable and predominant (≥80%) axial LBP resulting from DDD without any deformities or instabilities.

OUTCOME MEASURES

Visual analog scale (VAS), Oswestry Disability Index (ODI), and patient satisfaction rates (three-scale outcome rating); complication and reoperation rates as well as elapsed time until revision surgery; patient's professional activity/employment status.

METHODS

Clinical outcome scores were acquired within the framework of an ongoing prospective clinical trial. Patients were examined preoperatively, 3, 6, and 12 months postoperatively, annually from then onward. The data acquisition was performed by members of the clinic's spine unit including medical staff, research assistants, and research nurses who were not involved in the process of pre- or postoperative decision-making.

RESULTS

The initial cohort consisted of 201 patients; 181 patients were available for final FU, resembling a 90.0% FU rate after a mean FU of 7.4 years (range 5.0-10.8 years). The overall results revealed a highly significant improvement from baseline VAS and ODI levels at all postoperative FU stages (p<.0001). VAS scores demonstrated a slight (from VAS 2.6 to 3.3) but statistically significant deterioration from 48 months onward (p<.05). Patient satisfaction rates remained stable throughout the entire postoperative course, with 63.6% of patients reporting a highly satisfactory or a satisfactory (22.7%) outcome, whereas 13.7% of patients were not satisfied. The overall complication rate was 14.4% (N=26/181). The incidence of revision surgeries for general and/or device-related complications was 7.2% (N=13/181). Two-level TDRs demonstrated a significant improvement of VAS and ODI scores in comparison to baseline levels (p<.05). Nevertheless, the results were significantly inferior in comparison to one-level cases and were associated with higher complication (11.9% vs. 27.6%; p=.03) and inferior satisfaction rates (p<.003).

CONCLUSIONS

Despite the fact that the current data comprises the early experiences and learning curve associated with a new surgical technique, the results demonstrate satisfactory and maintained mid- to long-term clinical results after a mean FU of 7.4 years. Patient safety was proven with acceptable complication and reoperation rates. Fear of excessive late complications or reoperations following the primary TDR procedure cannot be substantiated with the present data. In carefully selected cases, TDR can be considered a viable treatment alternative to lumbar fusion for which spine communities around the world seem to have accepted mediocre clinical results as well as obvious and significant drawbacks.

Are Modic changes related to outcomes in lumbar disc herniation patients treated with imaging-guided lumbar nerve root blocks?

OBJECTIVE

To compare outcomes after imaging-guided transforaminal lumbar nerve root blocks in MRI confirmed symptomatic disc herniation patients with and without Modic changes (MC).

METHODS

Consecutive adult patients with MRI confirmed symptomatic lumbar disc herniations and an imaging-guided lumbar nerve root block injection who returned an outcomes questionnaire are included. Numerical rating scale (NRS) pain data was collected prior to injection and 20-30 min after injection. NRS and overall improvement were assessed using the patient's global impression of change (PGIC) scale at 1 day, 1 week and 1 month post injection. The proportion of patients with and without MC on MRI as well as Modic I and Modic II was calculated. These groups were compared for clinically relevant 'improvement' using the Chi-squared test. Baseline and follow-up NRS scores were compared for the groups using the unpaired t-test.

RESULTS

346 patients are included with MC present in 57%. A higher percentage of patients without MC reported 'improvement' and a higher percentage of patients with MC reported 'worsening' but this did not reach statistical significance. The numerical scores on the PGIC and NRS scales showed that patients with MC had significantly higher pain and worse overall improvement scores at 1 month (p=0.048 and p=0.03) and a significantly lower 1 month NRS change score (p=0.04).

CONCLUSIONS

Patients with MRI confirmed symptomatic lumbar disc herniations and MC report significantly lower levels of pain reduction after a lumbar nerve root block compared to patients without MC.

Efficacy of zoledronic acid for chronic low back pain associated with Modic changes in magnetic resonance imaging

BACKGROUND

Modic changes (MC) are associated with low back pain (LBP), but effective treatments are lacking. The aim of this randomized, placebo-controlled, double-blinded trial was to evaluate the efficacy of zoledronic acid (ZA) for chronic LBP among patients with MC in magnetic resonance imaging (MRI).

METHODS

Inclusion criteria were LBP lasting ≥3 months, with an intensity of ≥6 on a 10-cm VAS or an Oswestry Disability Index (ODI) of ≥30%, and MC in MRI. Patients were randomized into single intravenous infusion of ZA 5 mg (n = 20), or placebo (n = 20) groups. The primary outcome was LBP intensity, secondary outcomes leg pain intensity, ODI, health-related quality of life (RAND-36), lumbar flexibility, sick leaves and use of pain medication. The treatment differences at one month and one year were analysed using ANCOVA with adjustment for the baseline score.

RESULTS

The mean difference (MD) between the groups in the primary outcome, intensity of LBP, was 1.4 (95% confidence intervals (CI) 0.01 to 2.9) in favour of ZA at one month. We observed no significant between-group difference in the intensity of LBP at one year (MD 0.7; 95% CI -1.0 to 2.4) or in secondary outcomes at any time point except that 20% of patients in the ZA group used non-steroidal anti-inflammatory drugs at one year compared to 60% in the placebo group (P = 0.022). Acute phase reactions (fever, flu-like symptoms, arthralgia) emerged in 95% of the patients in the ZA group, compared to 35% in the placebo group.

CONCLUSIONS

ZA was effective in reducing the intensity of LBP in the short term and in reducing the use of NSAIDs within the time span of one year among patients with chronic LBP and MC confirmed in MRI. Although the results seem encouraging, larger studies are required to analyse the effectiveness and safety of ZA for patients with MC.

TRIAL REGISTRATION

ClinicalTrial.gov identifier NCT01330238.

Bilateral fracture of L5 pedicles in a patient with total disc replacement of L5-S1: a case report

Report of a rare complication - fracture of the pedicles - in a patient with total disc replacement of L5-S1, a surgical resolution, and a biomechanical explanation. To the authors' knowledge, there is only one previous report of bilateral fracture of the pedicles in the literature, as a complication in total disc replacement of the lumbar spine. In this case, no direct repair was made to the fracture site; instead intersomatic fusion was performed by the anterior approach. A 40-year-old male, a martial arts practitioner who had undergone L5-S1 (ProDisc(r)) disc replacement nine months earlier, with complete resolution of the preoperative symptoms and no complications, sudden pain during physical activity, without neurological symptoms. Computed axial tomography showed a fracture of the L5 pedicles and anterior luxation of the polyethylene insert. Surgery was performed by the posterior approach, with direct repair of the fractures and posterolateral fusion of L5-S1 with transpedicular screws (Schanz) and USS(r) internal fixator. A follow-up axial CT scan at 6 months after surgery showed complete consolidation of the fractures, and the patient was asymptomatic. Due to the alteration in weight transmission through the anterior part of the spine in the total replacement of the lumbar disc, which preserves the movement but not the absorption of forces, the pedicle becomes more susceptible to fracture. It is important to bear this complication in patients submitted to this procedure.

Lumbar total disc replacement: correlation of clinical outcome and radiological parameters

BACKGROUND

The objective of this study was to correlate various radiological parameters with clinical outcome in patients who had undergone lumbar total disc replacement (TDR). Lumbar TDR is one possible treatment option in patients with low back pain (LBP), offering an alternative to lumbar fusion. Favourable clinical outcome hinges on a number of radiological parameters, such as mobility, sintering, and-most importantly-accurate positioning of the implant.

METHODS

A total of 46 patients received a prosthetic disc because of degenerative lumbar disc disorders. Follow-up evaluation included analysis of radiographs and subjective rating of the clinical status by the patient using the North American Spine Society (NASS) patient questionnaire, visual analogue scale (VAS) for pain and state of health, and the EuroQol EQ-5D. Radiological follow-up took place after 2 years. Coronal and sagittal positions of the prosthesis, intervertebral disc height, facet joint pressure, mobility, sintering, and calcification were evaluated. Optimal positioning of the prosthesis was defined as a central coronal position and a most dorsal position in the sagittal plane. Based on the radiologically determined placement of the prosthesis, the patient population was divided into three groups, i.e., prosthesis ideally placed (<2 mm), discretely shifted (2-3 mm), or suboptimally placed (>3 mm).

RESULTS

Overall, 81 % of patients stated that they would undergo the operation again. Health status was stable at a VAS score of 7.04 points 2 years after TDR, compared to 3.97 points before TDR. Mean working capacity had increased from 53 % preoperatively to 88 % 2 years after TDR. Overall, 39 % of the prostheses were rated as ideally positioned, while 13 % were discretely shifted and 48 % were suboptimally placed with respect to one of the radiological criteria. In 80.4 % of patients, follow-up assessment after ≥2 years indicated good mobility at the operated segment, while calcification was noted in 4 % and sintering was detected in 15 % of the implants.

CONCLUSIONS

Our data indicate poor correlation between clinical outcome and position of the prosthesis. Although 48 % of the implants were suboptimally placed in either the coronal or sagittal plane, most of the patients reached a very good clinical outcome. However, suboptimally placed devices appeared to cause significantly more neurological symptoms in long-term follow-up.

Comparison of artificial total disc replacement versus fusion for lumbar degenerative disc disease: a meta-analysis of randomized controlled trials

Purpose

To compare the efficacy and safety of TDR to that of the fusion for the treatment of lumbar degenerative disc disease (LDDD).

Methods

Randomized controlled trials comparing TDR with any other intervention for LDDD were acquired by a comprehensive search in PubMedCentral, MEDLINE, EMBASE, BIOSIS, ClinicalTrials.gov, and the FDA trials register. Methodologic quality was assessed and relevant data were retrieved, and appropriate meta-analysis was performed. Two review authors independently selected studies, extracted data, and assessed risk of bias. Results and upper bounds of confidence intervals were compared with predefined clinically relevant differences.

Results

Six relevant randomized controlled trials (RCTs) involving 1,603 patients were identified and reported two year follow-up results. Patients in TDR group compared with lumbar fusion group demonstrated significant improvements in ODI, VAS scores and complication rates at the two year follow-up. Meanwhile, except for operating time in anterior group, intra-operative blood loss, operating time in posterior group, and reoperation rate were without clinical significance between the two groups. In addition, the range of motion (ROM) was maintained within normal ranges after TDR.

Conclusions

The results showed the TDR has significant safety and efficacy comparable to lumbar fusion at two year follow-up. Although superiority compared to fusion could not be proved, by comparing clinical symptoms relieved, motion preserved, and the low reoperation rate during long-term follow-up on TDR, TDR was considered safe and effective. Therefore, the authors suggest adopting TDR on a large scale; with failure of TDR, interbody fusion would be performed.

Posterior Transpedicular Dynamic Stabilization versus Total Disc Replacement in the Treatment of Lumbar Painful Degenerative Disc Disease: A Comparison of Clinical Results

Study Design. Prospective clinical study. Objective. This study compares the clinical results of anterior lumbar total disc replacement and posterior transpedicular dynamic stabilization in the treatment of degenerative disc disease. Summary and Background Data. Over the last two decades, both techniques have emerged as alternative treatment options to fusion surgery. Methods. This study was conducted between 2004 and 2010 with a total of 50 patients (25 in each group). The mean age of the patients in total disc prosthesis group was 37,32 years. The mean age of the patients in posterior dynamic transpedicular stabilization was 43,08. Clinical (VAS and Oswestry) and radiological evaluations (lumbar lordosis and segmental lordosis angles) of the patients were carried out prior to the operation and 3, 12, and 24 months after the operation. We compared the average duration of surgery, blood loss during the surgery and the length of hospital stay of both groups. Results. Both techniques offered significant improvements in clinical parameters. There was no significant change in radiologic evaluations after the surgery for both techniques. Conclusion. Both dynamic systems provided spine stability. However, the posterior dynamic system had a slight advantage over anterior disc prosthesis because of its convenient application and fewer possible complications.

Total disc replacement for chronic back pain in the presence of disc degeneration

BACKGROUND

In the search for better surgical treatment of chronic low-back pain (LBP) in the presence of disc degeneration, total disc replacement has received increasing attention in recent years. A possible advantage of total disc replacement compared with fusion is maintained mobility at the operated level, which has been suggested to reduce the chance of adjacent segment degeneration.

OBJECTIVES

The aim of this systematic review was to assess the effect of total disc replacement for chronic low-back pain in the presence of lumbar disc degeneration compared with other treatment options in terms of patient-centred improvement, motion preservation and adjacent segment degeneration.

SEARCH METHODS

A comprehensive search in Cochrane Back Review Group (CBRG) trials register, CENTRAL, MEDLINE, EMBASE, BIOSIS, ISI, and the FDA register was conducted. We also checked the reference lists and performed citation tracking of included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing total disc replacement with any other intervention for degenerative disc disease.

DATA COLLECTION AND ANALYSIS

We assessed risk of bias per study using the criteria of the CBRG. Quality of evidence was graded according to the GRADE approach. Two review authors independently selected studies and assessed risk of bias of the studies. Results and upper bounds of confidence intervals were compared against predefined clinically relevant differences.

MAIN RESULTS

We included 40 publications, describing seven unique RCT's. The follow-up of the studies was 24 months, with only one extended to five years. Five studies had a low risk of bias, although there is a risk of bias in the included studies due to sponsoring and absence of any kind of blinding. One study compared disc replacement against rehabilitation and found a statistically significant advantage in favour of surgery, which, however, did not reach the predefined threshold for clinical relevance. Six studies compared disc replacement against fusion and found that the mean improvement in VAS back pain was 5.2 mm (of 100 mm) higher (two studies, 676 patients; 95% confidence interval (CI) 0.18 to 10.26) with a low quality of evidence while from the same studies leg pain showed no difference. The improvement of Oswestry score at 24 months in the disc replacement group was 4.27 points more than in the fusion group (five studies; 1207 patients; 95% CI 1.85 to 6.68) with a low quality of evidence. Both upper bounds of the confidence intervals for VAS back pain and Oswestry score were below the predefined clinically relevant difference. Choice of control group (circumferential or anterior fusion) did not appear to result in different outcomes.

AUTHORS' CONCLUSIONS

Although statistically significant, the differences between disc replacement and conventional fusion surgery for degenerative disc disease were not beyond the generally accepted clinical important differences with respect to short-term pain relief, disability and Quality of Life. Moreover, these analyses only represent a highly selected population. The primary goal of prevention of adjacent level disease and facet joint degeneration by using total disc replacement, as noted by the manufacturers and distributors, was not properly assessed and not a research question at all. Unfortunately, evidence from observational studies could not be used because of the high risk of bias, while these could have improved external validity assessment of complications in less selected patient groups. Non-randomised studies should however be very clear about patient selection and should incorporate independent, blinded outcome assessment, which was not the case in the excluded studies. Therefore, because we believe that harm and complications may occur after years, we believe that the spine surgery community should be prudent about adopting this technology on a large scale, despite the fact that total disc replacement seems to be effective in treating low-back pain in selected patients, and in the short term is at least equivalent to fusion surgery.

Modic type I changes and recovery of back pain after lumbar microdiscectomy

PURPOSE

To investigate whether the presence of Modic changes type I (MC I) found on preoperative MRI scans represent a risk factor for persistent back pain 12 months after surgery amongst patients operated for lumbar disc herniation.

METHODS

Cohort study of 178 consecutive patients operated with lumbar microdiscectomy. Preoperative MRI scans were evaluated by two independent neuroradiologists. Primary outcome measure was the visual analogue scale (VAS) for back pain. Secondary outcome measures were; VAS for leg pain, physical function (Oswestry disability index), and health-related quality of life (EQ-5D), self-reported benefit of the operation and employment status. The presence of MC I was used as exposition variable and adjusted for other risk factors in multivariate analyses.

RESULTS

The Modic classification showed a high inter-observer reproducibility. Patients with MC I had less improvement of back pain 12 months after surgery, compared to those who had no or other types of MC, but this negative association no longer showed statistical significance when adjusted for smoking, which remained the only independent risk factor for persistent back pain.

CONCLUSIONS

Patients with preoperative MC I can expect less but still significant improvement of back pain 1 year after microdiscectomy, but not if they smoke cigarettes.

Parameters that effect spine biomechanics following cervical disc replacement

Total disc replacement (TDR) is expected to provide a more physiologic alternative to fusion. However, long-term clinical data proving the efficacy of the implants is lacking. Limited clinical data suggest somewhat of a disagreement between the in vitro biomechanical studies and in vivo assessments. This conceptual paper presents the potential biomechanical challenges affecting the TDR that should be addressed with a hope to improve the clinical outcomes and our understanding of the devices. Appropriate literature and our own research findings comparing the biomechanics of different disc designs are presented to highlight the need for additional investigations. The biomechanical effects of various surgical procedures are analyzed, reiterating the importance of parameters like preserving uncinate processes, disc placement and its orientation within the cervical spine. Moreover, the need for a 360° dynamic system for disc recipients who may experience whiplash injuries is explored. Probabilistic studies as performed already in the lumbar spine may explore high risk combinations of different parameters and explain the differences between "standard" biomechanical investigations and clinical studies. Development of a patient specific optimized finite element model that takes muscle forces into consideration may help resolve the discrepancies between biomechanics of TDR and the clinical studies. Factors affecting long-term performance such as bone remodeling, subsidence, and wear are elaborated. In vivo assessment of segmental spine motion has been, and continues to be, a challenge. In general, clinical studies while reporting the data have placed lesser emphasis on kinematics following intervertebral disc replacements. Evaluation of in vivo kinematics following TDR to analyze the quality and quantity of motion using stereoradiogrammetric technique may be needed.

Influence of lumbar intervertebral disc degeneration on the outcome of total lumbar disc replacement: a prospective clinical, histological, X-ray and MRI investigation

INTRODUCTION

The role of fusion of lumbar motion segments for the treatment of axial low back pain (LBP) from lumbar degenerative disc disease (DDD) without any true deformities or instabilities remains controversially debated. In an attempt to avoid previously published and fusion-related negative side effects, motion preserving technologies such as total lumbar disc replacement (TDR) have been introduced. The adequate extent of preoperative DDD for TDR remains unknown, the number of previously published studies is scarce and the limited data available reveal contradictory results. The goal of this current analysis was to perform a prospective histological, X-ray and MRI investigation of the index-segment's degree of DDD and to correlate these data with each patient's pre- and postoperative clinical outcome parameters from an ongoing prospective clinical trial with ProDisc II (Synthes, Paoli, U.S.A.).

MATERIALS AND METHODS

Nucleus pulposus (NP) and annulus fibrosus (AF) changes were evaluated according to a previously validated quantitative histological degeneration score (HDS). X-ray evaluation included assessment of the mean, anterior and posterior disc space height (DSH). MRI investigation of DDD was performed on a 5-scale grading system. The prospective clinical outcome assessment included visual analogue scale (VAS), Oswestry Disability Index (ODI) scores as well as the patient's subjective satisfaction rates.

RESULTS

Data from 51 patients with an average follow-up of 50.5 months (range 6.1-91.9 months) were included in the study. Postoperative VAS and ODI scores improved significantly in comparison to preoperative levels (p < 0.002). A significant correlation and interdependence was established between various parameters of DDD preoperatively (p < 0.05). Degenerative changes of NP tissue samples were significantly more pronounced in comparison to those of AF material (p < 0.001) with no significant correlation between each other (p > 0.05). Preoperatively, the extent of DDD was not significantly correlated with the patient's symptomatology (p > 0.05). No negative influence was associated with increasing stages of DDD on the postoperative clinical outcome parameters following TDR (p > 0.05). Increasing stages of DDD in terms of lower DSH scores were not associated with inferior clinical results as outlined by postoperative VAS or ODI scores or the patient's subjective outcome evaluation at the last FU examination (p > 0.05). Conversely, some potential positive effects on the postoperative outcome were observed in patients with advanced stages of preoperative DDD. Patients with more severe preoperative HDS scores of NP samples demonstrated significantly lower VAS scores during the early postoperative course (p = 0.02).

CONCLUSION

Increasing stages of DDD did not negatively impact on the outcome following TDR in a highly selected patient population. In particular, no preoperative DDD threshold value was identified from which an inferior postoperative outcome could have been deduced. Conversely, some positive effects on the postoperative outcome were detected in patients with advanced stages of DDD. Combined advantageous effects of progressive morphological structural rigidity of the index segment and restabilizing effects from larger distraction in degenerated segments may compensate for increasing axial rotational instability, one of TDR's perceived disadvantages. Our data reveal a "therapeutic window" for TDR in a cohort of patients with various stages of DDD as long as preoperative facet joint complaints or degenerative facet arthropathies can be excluded and stringent preoperative decision making criteria are adhered to. Previously published absolute DSH values as contraindication against TDR should be reconsidered.

Clinical outcome of lumbar total disc replacement using ProDisc-L in degenerative disc disease: minimum 5-year follow-up results at a single institute

STUDY DESIGN

A retrospective clinical data analysis.

OBJECTIVE

To determine the therapeutic effectiveness of lumbar total disc replacement (TDR) using ProDisc-L (Synthes Spine, West Chester, PA) in the patients with degenerative disc diseases (DDD) with a minimum follow-up of 5 years.

SUMMARY OF BACKGROUND DATA

Early successful clinical results of lumbar TDR have been reported. However, few reports have published its therapeutic effectiveness in the long term.

METHODS

The patients were examined preoperatively and at 3 months, 1 year, 2 years, and more than 5 years postoperatively, and assessed using visual analog scale (VAS), Oswestry disability index (ODI), physical health component summary (PCS) of the 36-Item Short Form Health Survey questionnaire, and sporting activity scale scores. At last follow-up visits, two additional questions were asked: satisfaction with surgery and willingness to undergo the same treatment. Finally, clinical success was assessed using the Food and Drug Administration definition.

RESULTS

Thirty-five patients were included in the study. The mean follow-up period was 72 months (6 years). Postoperatively, all outcome measure scores (VAS, mean ODI, PCS, and sports activity scores) immediately improved and these improvements were maintained at last follow-up visits with statistical significance. However, outcome score improvements were observed to be slightly, though significantly, lower at last follow-up visits than at 1 or 2 years postoperatively. Eighty-eight percent of patients were "satisfied" or "somewhat satisfied" with treatment and 60% were prepared to undergo the same treatment again. Twenty-five patients (71.4%) achieved clinical success.

CONCLUSION

This study reveals that lumbar TDR using ProDisc-L is a safe and effective treatment for chronic back pain caused by lumbar DDD as assessed at more than 5 years postoperatively. Nevertheless, outcome scores were slightly, though significantly lower at last follow-up visits than at 1 and 2 years postoperatively. A longer-term follow-up study is warranted.

Vertebral bone mineral measures and psychological wellbeing among individuals with modic changes

Purpose

This case-control pilot study examined whether vertebral bone mineral measures were associated with the presence of chronic low back pain (CLBP) and Modic changes (MCs), and to compare psychological wellbeing and inflammation among individuals with CLBP and MCs, compared to individuals with no history of low back pain and without MCs.

Methods

Eleven individuals with MRI-defined MCs in the lumbar spine and CLBP (cases) and 10 individuals with no history of CLBP or MCs (controls) responded to standard questionnaires regarding pain characteristics and psychological health. Bone mineral density (BMD) was measured with postero-anterior and lateral-projection dual energy X-ray absorptiometry (DXA) to estimate areal BMD (aBMD) and apparent volumetric BMD (ap.vBMD). High sensitivity serum C-reactive protein (hsCRP) was measured as an index of inflammation.

Results

While there was no difference between the groups in measures of depression, anxiety and stress, cases reported significantly greater pain catastrophizing attitudes (P < 0.01). hsCRP concentrations did not differ between groups (P = 0.54). Among the 7 cases where MCs were identified between L3–4, significantly higher mean aBMD was observed at the affected vertebral level, compared to the adjacent, unaffected, cephalad level (P = 0.01–0.04), but not when ap.vBMD was calculated (P = 0.36).

Conclusions

Vertebral BMD is not reduced among individuals with CLBP and MCs compared to a control group, although pain catastrophizing attitudes are increased among individuals with CLBP and MCs.

Clinical results of lumbar total disc arthroplasty in accordance with Modic signs, with a 2-year-minimum follow-up

STUDY DESIGN

Prospective study.

OBJECTIVE

The aim of this prospective study is to analyze the influence of Modic type on the clinical results of lumbar total disc arthroplasty.

SUMMARY OF BACKGROUND DATA

Some patients with lumbar disc degeneration have endplate signal changes on magnetic resonance images, which have been classified by Modic. Modic-1 endplates changes are associated with an inflammatory phase of the disease whereas Modic-2 endplates changes correspond to a quiescent phase with a fatty replacement. The effect of Modic endplate changes on the clinical results of lumbar fusion has been studied by multiple authors, but the influence of Modic type on clinical outcomes of lumbar disc replacement is not known.

METHODS

A total of 221 patients with a mean age of 42 years were included in this study. Of which, 107 patients were classified Modic 0, 65 Modic 1, and 49 Modic 2. Clinical evaluation (Oswestry Disability Index [ODI], lumbar and radicular pain using the Visual Analog Score [VAS]) was performed preoperatively and at 3, 6, 12, and 24 months minimum postoperatively.

RESULTS

Mean follow-up was 30 months (24-72 months). Significant clinical improvement (P < 0.05) was observed in pain and ODI between the preoperative evaluation and final follow-up. Multivariate analysis between the 3 groups demonstrated a significant difference in Oswestry Disability Index (size of the effect was measured at -0.3 [-0.55-0.04]) and on the radicular pain (size of the effect was measured at -0.4 [-0.7-0.1]), with lower scores in the group classified Modic 1.

CONCLUSION

Superior results were achieved in the group of patients with Modic-1 endplate changes on magnetic resonance images. These data may be helpful in patient selection and in preoperative patient counseling.

Influence of preoperative nucleus pulposus status and radiculopathy on outcomes in mono-segmental lumbar total disc replacement: results from a nationwide registry

Background

Currently, herniated nucleus pulposus (HNP) with radiculopathy and other preconditions are regarded as relative or absolute contraindications for lumbar total disc replacement (TDR). In Switzerland it is left to the surgeon's discretion when to operate. The present study is based on the dataset of SWISSspine, a governmentally mandated health technology assessment registry. We hypothesized that preoperative nucleus pulposus status and presence or absence of radiculopathy has an influence on clinical outcomes in patients treated with mono-segmental lumbar TDR.

Methods

Between March 2005 and April 2009, 416 patients underwent mono-segmental lumbar TDR, which was documented in a prospective observational multicenter mode. The data collection consisted of perioperative and follow-up data (physician based) and clinical outcomes (NASS, EQ-5D).

Patients were divided into four groups according to their preoperative status: 1) group degenerative disc disease ("DDD"): 160 patients without HNP and no radiculopathy, classic precondition for TDR; 2) group "HNP-No radiculopathy": 68 patients with HNP but without radiculopathy; 3) group "Stenosis": 73 patients without HNP but with radiculopathy, and 4) group "HNP-Radiculopathy": 132 patients with HNP and radiculopathy. The groups were compared regarding preoperative patient characteristics and pre- and postoperative VAS and EQ-5D scores using general linear modeling.

Results

Demographics in all four groups were comparable. Regarding the improvement of quality of life (EQ-5D) there were no differences across the four groups. For the two main groups DDD and HNP-Radiculopathy no differences were found in the adjusted postoperative back- and leg pain alleviation levels, in the stenosis group back- and leg pain relief were lower.

Conclusions

Despite higher preoperative leg pain levels, outcomes in lumbar TDR patients with HNP and radiculopathy were similar to outcomes in patients with the classic indication; this because patients with higher preoperative leg pain levels benefit from a relatively greater leg pain alleviation. The group with absence of HNP but presence of radiculopathy showed considerably less benefits from the operation, which is probably related to ongoing degenerative processes of the posterior segmental structures. This observational multicenter study suggests that the diagnoses HNP and radiculopathy, combined or alone, may not have to be considered as absolute or relative contraindications for mono-segmental lumbar TDR anymore, whereas patients without HNP but with radiculopathy seem to be suboptimal candidates for the procedure.

Lumbar disc arthroplasty with Maverick disc versus stand-alone interbody fusion: a prospective, randomized, controlled, multicenter investigational device exemption trial

STUDY DESIGN

Randomized, controlled, multicenter, investigational device exemption trial.

OBJECTIVE

To investigate the safety and effectiveness of the first two-piece, metal-on-metal lumbar disc prosthesis for treating patients with single-level degenerative disc disease.

SUMMARY OF BACKGROUND DATA

For patients with degenerative disc disease unresponsive to conservative measures, lumbar disc arthroplasty provides an alternative to fusion designed to relieve persistent discogenic pain and maintain motion.

METHODS

After 2:1 randomization, 577 patients were treated in either the investigational group (405), receiving lumbar disc arthroplasty, or the control group (172), receiving anterior lumbar interbody fusion. Patients were evaluated preoperatively, at surgery/discharge, and at 1.5, 3, 6, 12, and 24 months after surgery. The primary study endpoint was overall success, a composite measure of safety and effectiveness as recommended by the Food and Drug Administration and defined in the protocol.

RESULTS

Both treatment groups demonstrated significant improvements compared with preoperative status. The investigational group had statistically superior outcomes (P < 0.05) at all postoperative evaluations in Oswestry Disability Index, back pain, and Short Form-36 Physical Component Summary scores as well as patient satisfaction. Investigational patients had longer surgical times (P < 0.001) and greater blood loss (P < 0.001) than did control patients; however, hospitalization stays were similar for both groups. Investigational patients had fewer implant or implant/surgical procedure-related adverse events (P < 0.001). Return-to-work intervals were reduced for investigational patients. Disc height and segmental angular motion were maintained throughout the study in the investigational group. In the investigational group, overall success superiority was found when compared to the control group as defined by the Food and Drug Administration Investigational Device Exemption protocol.

CONCLUSION

The investigational group consistently demonstrated statistical superiority versus fusion on key clinical outcomes including improved physical function, reduced pain, and earlier return to work.

Disc height and motion patterns in the lumbar spine in patients operated with total disc replacement or fusion for discogenic back pain. Results from a randomized controlled trial

BACKGROUND CONTEXT

Fusion is considered the "gold standard" in surgical treatment of degenerated disc disease; the intended postoperative goal is absence of mobility, but treatment may induce degeneration in adjacent segments. Total disc replacement (TDR) aims to restore and maintain mobility by replacing a painful disc. Little is known about the degree and quality of mobility in artificial discs in vivo and whether maintained mobility reduces the stress on adjacent segments that is believed to occur after fusion.

PURPOSE

To see if surgical goals for respective treatments had been reached, if clinical outcome was related to this, and if differences in disc height at treated segments and adjacent segment motion patterns between groups occurred.

STUDY DESIGN

Comparison of X-ray measurements in a randomized controlled trial between instrumented posterior fusion and TDR for chronic low back pain (CLBP) assumed to be discogenic. Results were compared with clinical outcome.

PATIENT SAMPLE

The material consisted of 152 patients suffering from CLBP assumed to be discogenic. Seventy-two patients were treated with fusion and 80 with TDR.

OUTCOME MEASURES

Results of X-ray measurements were compared between groups and related to self-reported clinical results regarding back pain and disability.

METHODS

Flexion-extension X-rays were analyzed preoperatively and 2 years postoperatively using distortion-compensated Roentgen analysis (DCRA) at treated and adjacent levels, and mobility after fusion and TDR was estimated. Changes in disc height and range of motion (ROM) respective translation in adjacent segments were compared between groups. Results of DCRA measurements were also compared with the clinical outcome.

RESULTS

Preoperative flexion-extension ROM was similar between the fusion and TDR groups, and preoperative disc heights of segments to be treated were between one and two standard deviation less than that previously established in a normative database. Seventy percent of fused patients had no mobility, whereas 85% of TDR patients were mobile. Fulfillment of surgical goals was correlated to neither back pain nor disability. Fused segments were lower and TDR segments were higher than normative values postoperatively. There were also significant differences at adjacent segments, there being more translation and flexion-extension in the fusion group than in the TDR group.

CONCLUSIONS

This very accurate X-ray method (DCRA) indicates that surgical goals were reached in most patients. This, however, was not correlated to clinical outcome. Differences between the groups in postoperative disc height at treated segments, respective ROM, and translation at adjacent segments did not affect the clinical outcome after 2 years.