Lumbar Total Disk Replacement Device Removals and Revisions Performed During a 20-Year Experience with 2141 Patients

STUDY DESIGN

This was a retrospective study with prospective patient contact attempted to collect current data.

OBJECTIVE

The purpose was to investigate the incidence and reasons for lumbar total disk replacement (TDR) removal or revision.

SUMMARY OF BACKGROUND DATA

A concern regarding lumbar TDR was safety, particularly the need for device removal or revision. This may be particularly important considering removal/revision requires repeat anterior exposure with an increased risk of vascular injury.

METHODS

Data were collected for a series of 2141 lumbar TDR patients, beginning with the first case experience in 2000. The mean follow-up was 78.6 months. For each case of device removal/revision, the reason, duration from index surgery, and procedure performed were recorded.

RESULTS

Of 2141 patients, 27 (1.26%) underwent TDR removal or revision. Device removal was performed in 24 patients (1.12%), while three patients underwent revision (0.14%). Of the 24 removals, 12 were due to migration and/or loosening, three developed problems post-trauma, two developed lymphocytic reaction to device materials, two had ongoing pain, and there was one case of each: TDR was too large, vertebral body fracture (osteoporosis), lytic lesion, device subsidence and facet arthrosis, and infection seeded from a chest infection 146 months post-TDR. The three revisions were for Core repositioning (technique error), device repositioning after displacement, and core replacement due to wear/failure. With respect to timing, 37.0% of removals/revisions occurred within one-month postimplantation. Of note, 40.7% of removals/revisions occurred in the first 25 TDR cases performed by individual surgeons. There was one significant vascular complication occurring in a patient whose TDR was removed due to trauma. This was also the only patient among 258 with ≥15-year follow-up who underwent removal/revision.

CONCLUSION

In this large consecutive series, 1.26% of TDRs were removed/revised. The low rate over a 20 year period supports the safety of these devices.

Comparing outcomes between anterior cervical disc replacement (ACDR) and minimally invasive posterior cervical foraminotomy (MI-PCF) in the treatment of cervical radiculopathy

BACKGROUND CONTEXT

Anterior cervical disc replacement (ACDR) and minimally invasive posterior cervical foraminotomy (MI-PCF) have emerged as two increasingly popular alternatives to anterior cervical discectomy and fusion (ACDF) for the management of cervical radiculopathy. Both techniques provide advantages of segmental motion preservation and lower rates of adjacent segment degeneration (ASD) compared to ACDF.

PURPOSE

The purpose of this study was to analyze the clinical and functional outcomes of patients undergoing ACDR or MI-PCF for the treatment of unilateral cervical radiculopathy.

STUDY DESIGN/SETTING

Retrospective Cohort Review.

PATIENT SAMPLE

A total of 152 patients were included (86 ACDR and 66 MI-PCF).

OUTCOME MEASURES

(1) Patient demographics; (2) perioperative data; (3) rates of complications and revisions; (5) visual analogue scale (VAS) and Neck Disability Index (NDI) scores.

METHODS

A retrospective cohort review was performed to identify all patients at a single institution between 2012-2020 who underwent 1- or 2- level ACDR or MI-PCF from C3-C7 with a minimum follow-up of 24 months. Patient demographics, perioperative data, postoperative complications, and revisions were analyzed. Patient reported outcome measures including VAS and NDI scores were compared.

RESULTS

The ACDR group had a significantly greater mean operative time (99.8 minutes vs 79.2 minutes, p<.001), but comparable estimated blood loss and length of stay following surgical intervention (p=.899). The overall complication rate was significantly greater in the ACDR group than the MI-PCF group (24.4% vs 6.2%; p=.003) but was largely driven by approach-related dysphagia in 20.9% of ACDR patients. The MI-PCF group had significantly greater revision rates (13.6% vs 1.2%; p=.002) with an average time to revision of 20.7 months in the MI-PCF group compared to 40.3 months in the ACDR group. The ACDR cohort had significantly greater improvements in NDI scores at the final follow-up (25.0 vs 21.3, p<.001).

CONCLUSION

Our results suggest that ACDR offer clinically relevant advantages over MI-PCF in terms of long-term revision rates despite an increased approach-related risk of transient postoperative dysphagia. Additionally, patients in the ACDR cohort achieved greater mean improvements in NDI scores but these results may have limited clinical significance due to inability to reach minimally clinically important difference (MCID) thresholds.

Heterotopic ossification, osteolysis and implant failure following cervical total disc replacement with the M6-C™ artificial disc

INTRODUCTION

A recent study reported a 34% mid-term revision rate after M6-C™ cervical total disc replacement (CTDR) for wear-related osteolysis. Here, we aim to investigate the prevalence, risk factors, and radiographic characteristics of periprosthetic bony changes and implant failure of the M6-C™ artificial disc.

METHODS

We retrospectively analysed radiographic (conventional X-ray, CT scan) and clinical outcomes (EQ-5D-5L, Neck Disability Index (NDI), and Visual Analog Scale (VAS) for neck and arm pain) data collected during routine follow-up of patients who underwent CTDR with the M6-C™ between 2011 and 2015.

RESULTS

In total, 85 patients underwent CTDR with the M6-C™. Follow-up data were available for 43 patients (54% female, mean age 44 years) with 50 implants and a mean follow-up of 8.1 years (6.5-11 years). Implant failure with the presence of severe osteolysis was identified in 5 (12%) patients who were all male (p = 0.016) and implanted at the C5/6 level (p = 0.11). All failed implants required revision surgery. The overall prevalence of osteolysis was 44% (22/50 implants) and 34% (17/50 implants) for significant heterotopic ossification. Patients with high-grade osteolysis showed higher VAS arm pain (p = 0.05) and lower EQ-5D-VAS health VAS (p = 0.03).

CONCLUSION

We report a lower reoperation rate for failed M6-C™ implants than previously published, but confirmed that osteolysis and heterotopic ossification are common following CTDR with the M6-C™ and may be asymptomatic. Therefore, we strongly recommend ongoing clinical and radiographic monitoring after CTDR with the M6-C™, particularly for male patients implanted at the C5/6 level.

Prospective, multicenter clinical trial comparing the M6-C compressible cervical disc with anterior cervical discectomy and fusion for the treatment of single-level degenerative cervical radiculopathy: 5-year results of an FDA investigational device exemption study

BACKGROUND CONTEXT

Various total disc replacement (TDR) designs have been compared to anterior cervical discectomy and fusion (ACDF) with favorable short and long-term outcomes in FDA-approved investigational device exemption (IDE) trials. The unique design of M6-C, with a compressible viscoelastic nuclear core and an annular structure, has previously demonstrated favorable clinical outcomes through 24 months.

PURPOSE

To evaluate the long-term safety and effectiveness of the M6-C compressible artificial cervical disc and compare to ACDF at 5 years.

STUDY DESIGN

Prospective, multicenter, concurrently and historically controlled, FDA-approved IDE clinical trial.

PATIENT SAMPLE

Subjects with one-level symptomatic degenerative cervical radiculopathy were enrolled and received M6-C (n=160) or ACDF (n=189) treatment as part of the IDE study. Safety outcomes were evaluated at 5 years for all subjects. The primary effectiveness endpoint was available at 5 years for 113 M6-C subjects and 106 ACDF controls.

OUTCOME MEASURES

The primary endpoint of this analysis was composite clinical success (CCS) at 60 months. Secondary endpoints were function and pain (neck disability index, VAS), physical quality of life (SF-36, SF-12), safety, neurologic, and radiographic assessments.

METHODS

Propensity score subclassification was used to control for selection bias and match baseline covariates of the control group to the M6-C subjects. Sixty-month CCS rates were estimated for each treatment group using a generalized linear model controlling for propensity score.

RESULTS

At 5 years postoperatively, the M6-C treatment resulted in 82.3% CCS while the ACDF group showed 67.0% CCS (superiority p=.013). Secondary endpoints indicated that significantly more M6-C subjects achieved VAS neck and arm pain improvements and showed maintained or improved physical functioning on quality-of-life measures compared to baseline assessments. The M6-C group-maintained flexion-extension motion, with significantly greater increases from baseline disc height and disc angle than observed in the control group. The rates of M6-C subsequent surgical interventions (SSI; 3.1%) and definitely device- or procedure-related serious adverse events (SAE failure; 3.1%) were similar to ACDF rates (SSI=5.3%, SAE failure=4.8%; p>.05 for both).

CONCLUSIONS

Subjects treated with the M6-C artificial disc demonstrated superior 5-year achievement of clinical success when compared to ACDF controls. In addition, significantly more subjects in the M6-C group showed improved pain and physical functioning scores than observed in ACDF subjects, with no difference in reoperation rates or safety outcomes.

Adjacent segment degeneration after single- and double-level cervical total disc replacement: a cohort with an over 12-year follow-up

PURPOSE

To characterize the change of adjacent segment degeneration (ASD) after cervical total disc replacement (CTDR) with more than 12-year follow-up, and identify the risk factors for ASD.

METHOD

This process included 75 patients underwent CTDR from February 2004 to December 2012, with the follow-up of 151.9 ± 36.0 (m). The artificial disc included ProDisc-C, Prestige-LP and Mobi-C. ASD was followed up at 1 week, 6 months, 1 year, 2 years, 5 years, 10 years after CTDR and at the endpoint of June 2022. The radiographic measurements were cervical mobility, intervertebral disc height (IDH), cervical lordosis and balance status. The complications were implant migration, subsidence and heterotopic ossification (HO).

RESULTS

Cervical mobility in adjacent segments, IDH and lordosis showed no statistical differences between ASD and NASD group. Balance status, subsidence and migration showed no relationship with ASD. Postoperative ASD increased at 6 m and especially between 6 m to 2y. There was no difference between the incidence of upper ASD and lower ASD all the time and few ASD-related reoperation. The majority of adjacent segments were C4/5 (33.6%) and C6/7 (34.2%), and ASD of C5/6 had the highest incidence (61.5%). Cox regression showed ASD was not related to the types of prosthesis or operated numbers. Generalized estimating equations (GEE) analysis showed severe HO had a higher (2.68 times) probability to suffer from ASD.

CONCLUSIONS

After over 12-year follow-up of CTDR, the occurrence of ASD and HO had temporal synchronization. ASD was not merely a natural progression but with the pathological process such as HO.

Headache relief 10 years after cervical disc arthroplasty: multicenter randomized clinical trial post hoc analysis

OBJECTIVE

Headache relief after anterior cervical spine surgery has been reported. No study, however, has followed patients out to 10 years to assess the durability of headache improvement. The authors analyzed a group of patients with a 10-year follow-up after one- or two-level cervical disc arthroplasty (CDA) from an FDA investigational device exemption (IDE) study.

METHODS

The authors performed a post hoc analysis of 189 patients treated with CDA from the 9 highest enrolling sites in a prospective multicenter randomized US FDA IDE clinical trial. Patients had one- or two-level CDA at contiguous levels from C3 to C7 using the Mobi-C device. The authors evaluated headache scores from the headache section of the Neck Disability Index (NDI), along with associated demographic variables (age, sex, race, ethnicity, and BMI). Preoperative and 10-year postoperative headache scores were analyzed. Primary analysis was conducted via the Wilcoxon rank-sum test, followed by univariate and multivariable logistic regression.

RESULTS

After accounting for age, BMI, race, ethnicity, and sex, there was sustained headache improvement 10 years after CDA (p = 0.04). Preoperatively, the median NDI score was 3.00 (IQR 1.00-4.00) and after 10 years it was 1.00 (IQR 0.00-2.00), with a decrease in the NDI score by 1.00 point (95% CI 0.00-2.00, p = 0.04). For one-level CDA, the median NDI score was 3.00 (IQR 1.00-4.00) preoperatively but 1.00 (IQR 0.00-2.00) at 10 years, with an estimated reduction in the NDI score of 1 point (95% CI 1.00-2.00, p < 0.0001). For two-level CDA, the median NDI score was 3.00 (IQR 1.75-4.00) preoperatively and 1.00 (IQR 0.00-2.00) at 10 years, with an estimated reduction in the NDI score of 1 point (95% CI 1.00-2.00, p < 0.0001).

CONCLUSIONS

Headache relief provided by cervical CDA, for symptomatic C3-7 cervical spondylosis, was sustained even 10 years after surgery. There was no difference in headache improvement between the one- and two-level CDA groups, or among BMI, sex, race, and ethnicity strata.

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

BACKGROUND CONTEXT

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

PURPOSE

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

STUDY DESIGN

Retrospective case-control study.

PATIENT SAMPLE

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

OUTCOME MEASURES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Intervertebral (lumbar) disc replacement:the current state and future perspectives

PURPOSE

Low back pain is a significant socio-economic problem which is expected to deepen. Degenerative disc disease is considered to be one of its main causes. Unsuccessful conservative treatments usually lead to surgical treatments, including methods providing pain relief by vertebral fusion in the affected segment. However, this leads to changes in biomechanics, which is why approximately 30 years ago total disc replacements appeared. This work aims at determining the current state of treatments with this kind of replacement, comparing the results with those of fusion methods and assessing why fusion continues to dominate. Current treatments of degenerative disc disease by advanced procedures (regenerative and gene therapy, 3D printing) is also examined and evaluated, and future developments are considered.

METHODS

A critical review based on available scientific articles from online databases. The main keywords used were "lumbar", "total", "disc" and "replacement", supplemented according to the individual, monitored areas ("follow-up", "fusion", "future" etc.). For the articles found through database search (n = 895), narrower selection was made and the result was 33 articles included in review.

REVIEW

Total disc replacements have not yet satisfactorily demonstrated that they are superior to fusion methods in long term follow-up. Advanced methods are in their infancy.

CONCLUSIONS

Additional research and development of total disc replacements is still necessary. For implants, the 3D scan - 3D model - 3D printing chain and its related technologies are increasingly important. The development of regenerative procedures using induced pluripotent stem cells and gene therapies is important, but conservative treatments and primary prevention should also be developed because regenerative procedures and gene therapies apparently will not be used routinely until the future.

Cervical disc arthroplasty with the Baguera C prosthesis: clinical and radiological results of a 10-year follow-up study

PURPOSE

We evaluated the long-term safety, mobility and complications of cervical total disc arthroplasty with the Baguera®C prosthesis over 10 years.

METHODS

We included 91 patients treated by arthroplasty for cervical degenerative disc disease. A total of 113 prostheses were implanted (50 one-level, 44 two-level and 19 hybrid constructs). They were assessed for complications, clinically, with NDI and SF-12 questionnaires and by independent radiologists for ROM, HO, disc height and adjacent level degeneration.

RESULTS

No spontaneous migration, loss of fixation, subsidence, vascular complication or dislocation were observed. The reoperation rate was 1%. About 82.7% of the patients were pain free. About 9.9% were taking occasional grade I painkillers. Motricity and sensitivity were preserved in 98.8% and 96.3%. The NDI showed an average functional disability of 17.58%, 26% lower than preoperatively. The SF-12 scores were close to normal health. The average ROM at the treated level was 7.4°. Motion was preserved in 86.6%. Lack of motion was observed in 13.4%. Grades II and III H0 were present in 53.7% and 31.7%, respectively, Grade IV was present in 13.4%. Motion was preserved in 100% of the grades 0-III. The preoperative adjacent level disc height of 4.3 mm remained stable during all the follow-ups at 4.4 mm and 4.2 mm, respectively, at 5 and 10 years.

CONCLUSIONS

After 10 years, cervical arthroplasty with the Baguera®C prosthesis presents excellent safety and functional results and low complications. Motion was preserved in 86.6%, with a 7.4° ROM. Although common, HO did not hinder motion. Adjacent disc height preservation confirms some adjacent level degeneration protection.

Incidence of Heterotopic Ossification at 10 years After Cervical Disk Replacement: A Systematic Review and Meta-analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

This study aimed to assess the incidence of heterotopic ossification (HO) 10 years after cervical disk replacement (CDR).

SUMMARY OF BACKGROUND DATA

HO is a common complication after CDR and may limit the range of motion of the artificial disk. As HO usually progresses slowly, a long-term follow-up is required to better understand its incidence. In recent years, the increasing number of original articles reporting 10-year outcomes gives us the opportunity to better understand the long-term incidence of HO.

MATERIALS AND METHODS

We searched PubMed, Medline, Embase, and Cochrane Library databases to identify eligible studies. The incidence of HO was pooled, and subgroup analysis was performed. Meta-regression analyses were conducted to identify factors contributing to heterogeneity.

RESULTS

Eleven studies with at least 10 years of follow-up comprising 1140 patients who underwent CDR were included. The pooled incidence of overall HO was 70% (95% CI, 60%-81%) at 10 years postoperatively, 60% (95% CI, 44%-75%) at five or six years postoperatively, and 50% (95% CI, 27%-72%) at one or two years postoperatively. The pooled incidence of severe HO (grade 3 or 4) was 37% (95% CI, 29%-45%), and mild HO (grade 1 to 2) was 30% (95% CI, 17%-44%) at 10 years of follow-up. Pooled range of motion decreased from 8.59° before surgery to 7.40° 10 years after surgery. Subgroup analysis showed that HO incidence differed according to the prosthesis type. The earlier publication was associated with a higher pooled incidence of severe HO in the meta-regression analysis.

CONCLUSIONS

This is the first meta-analysis providing detailed information on the pooled 10-year incidence of HO after CDR. The incidence of HO seems to increase with the length of follow-up.

LEVEL OF EVIDENCE

3.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Trends in use, outcomes, and revision procedures of anterior cervical disc replacement in the United States: a premiere database analysis from 2006-2019

PURPOSE

We sought to characterize trends in demographics, comorbidities, and postoperative complications among patients undergoing primary and revision cervical disc replacement (pCDR/rCDR) procedures.

METHODS

In this retrospective database study, the Premier Healthcare database was queried from 2006 to 2019. Annual proportions or medians were calculated for patient and hospital characteristics, comorbidities, and postoperative complications associated with CDR surgery. Trends were assessed using linear regression analyses with year of service as the sole predictor.

RESULTS

A total of 16,178 pCDR and 758 rCDR cases were identified, with a median (IQR) age of 46 (39; 53) and 51 (43; 60) years among patients, respectively. The annual number of both procedures increased between 2006 and 2019, from 135 to 2220 for pCDR (p < 0.001), and from 17 to 49 for rCDR procedures (p < 0.001), with radiculopathy being the main indication for surgery in both groups. Mechanical failure was identified as a major indication for rCDR procedures with an increase over time (p = 0.002). Baseline patient comorbidity burden (p = 0.045) and complication rates (p < 0.001) showed an increase. For both procedures, an increase in outpatient surgeries and procedures performed in rural hospitals was seen (pCDR: p = 0.045; p = 0.006; rCDR: p = 0.028; p = 0.034).

CONCLUSION

PCDR and rCDR procedures significantly increased from 2006 to 2019. At the same time, comorbidity burden and complication rates increased, while procedures were more often performed in an outpatient and rural setting. The identification of these trends can help guide future practice and lead to further areas of research.

Safety and Validity of Anterior Cervical Disc Replacement for Single-level Cervical Disc Disease: Initial Two-year Follow-up of the Prospective Observational Post-marketing Surveillance Study for Japanese Patients

Anterior cervical disc replacement (ACDR) using cervical artificial disc (CAD) has the advantage of maintaining the range of motion (ROM) at the surgical level, subsequently reducing the postoperative risk of adjacent disc disease. Following the approval for the clinical use in Japan, a post-marketing surveillance (PMS) study was conducted for two different types of CAD, namely, Mobi-C (metal-on-plastic design) and Prestige LP (metal-on-metal design). The objective of this prospective observational multicenter study was to analyze the first 2-year surgical results of the PMS study of 1-level ACDR in Japan. A total of 54 patients were registered (Mobi-C, n = 24, MC group; Prestige LP, n = 30, PLP group). Preoperative neurological assessment revealed radiculopathy in 31 patients (57.4%) and myelopathy in 15 patients (27.8%). Preoperative radiological assessment classified the disease category as disc herniation in 15 patients (27.8%), osteophyte in 6 patients (11.1%), and both in 33 patients (61.1%). The postoperative follow-up rates at 6 weeks, 6 months, 1 year, and 2 years after ACDR were 92.6%, 87.0%, 83.3%, and 79.6%, respectively. In both groups, patients' neurological condition improved significantly after surgery. Radiographic assessment revealed loss of mobility at the surgical level in 9.5% of patients in the MC group and in 9.1% of patients in the PLP group. No secondary surgeries at the initial surgical level and no serious adverse events were observed in either group. The present results suggest that 1-level ACDR is safe, although medium- to long-term follow-up is mandatory to further verify the validity of ACDR for Japanese patients.

Correlation between the degree of pain relief following discoblock and short-term surgical disability outcome among patients with suspected discogenic low back pain

OBJECTIVES

To evaluate how well the degree of pain relief after discoblock predicts the disability outcome of subsequent fusion or total disc replacement (TDR) surgery, based on short-term Oswestry Disability Index (ODI) scores.

METHODS

We retrospectively analyzed a set of patients who had undergone discoblock and subsequent fusion or TDR surgery of the same lumbar intervertebral disc due to suspected discogenic chronic LBP between 2011 and 2018. We calculated the degree of pain relief following discoblock (ΔNRS) and the changes in both absolute and percentual ODI scores (ΔODI and ΔODI%, respectively) following fusion or TDR surgery. We analyzed the statistical significance of ΔNRS and ΔODI and the correlation (Spearman's rho) between ΔNRS and ΔODI%. The fusion and TDR group were analyzed both in combination and separately.

RESULTS

Fifteen patients were eligible for the current study (fusion n=9, TDR n=6). ΔNRS was statistically significant in all groups, and ΔODI was statistically significant in the combined group and in the fusion group alone. The parameters of both decreased. We found a Spearman's rho of 0.57 (p=0.026) between ΔNRS and ΔODI% for the combined group. The individual Spearman's rho values were 0.85 (p=0.004) for the fusion group and 0.62 (p=0.191) for the TDR group.

CONCLUSIONS

We suggest that discoblock is a useful predictive criterion for disability outcome prior to surgery for discogenic LBP, especially when stabilizing spine surgery is under consideration.

ETHICAL COMMITTEE NUMBER

174/2019 (Oulu University Hospital Ethics Committee).

The Clinical Relevance of the Cervical Disc Prosthesis: Combining Clinical Results of Two RCTs

STUDY DESIGN

Retrospective analysis was performed on data from 251 patients that were included in two randomized, double-blinded clinical trials comparing clinical results of anterior cervical discectomy and arthroplasty (ACDA) to anterior cervical discectomy and fusion (ACDF), and anterior cervical discectomy (ACD), for single-level disc herniation.

OBJECTIVE

This study aimed to investigate whether the ACDA procedure offers superior clinical results 2 years after surgery, to either ACDF or ACD without instrumentation, in the entire group of patients or in a particular subgroup of patients.

SUMMARY OF BACKGROUND DATA

The cervical disc prosthesis was introduced to provide superior clinical outcomes after ACD.

METHODS

Neck Disability Index (NDI), and subscales of the 36-item short-form health survey (SF-36) and McGill pain score were collected at baseline, 1 year and 2 years after surgery. Reoperations and complications were also evaluated. A preliminary subgroup analysis was performed for age, disc height, body mass index (BMI), smoking, and sex.

RESULTS

The NDI decreased comparably in all treatment arms to circa 50% of the baseline value and marginal mean NDI differences varied from 0.4 to 1.1 on a 100 point NDI scale, with confidence intervals never exceeding the 20-point minimal clinical important difference (MCID). Secondary outcome parameters showed comparable results. Preliminary subgroup analysis could not demonstrate clinically relevant differences in NDI between treatments after 2 years.

CONCLUSION

After combining data from two Randomized Controlled Trials it can be concluded that there is no clinical benefit for ACDA, when compared with ACDF or ACD 2 years after surgery. Preliminary subgroup analysis indicated outcomes were similar between treatment groups, and that no subgroup could be appointed that benefited more from either ACD, ACDF, or ACDA.Level of Evidence: 1.

Effect of Disc Height and Degree of Distraction on Heterotopic Ossification After Cervical Disc Replacement

BACKGROUND

Heterotopic ossification (HO) is a potential and severe complication of cervical disc replacement (CDR). However, the underlying mechanism of CDR and its association with preoperative disc height loss (DHL) and postoperative degree of distraction remain unclear. We hypothesized that DHL and postoperative degree of distraction could predict HO after CDR.

METHODS

Data were obtained from 127 patients who underwent single-level CDR with a minimum follow-up of 2 years. DHL and adjusted degree of distraction (ADD) were obtained from lateral radiographs, and HO was evaluated at the last follow-up appointment. Receiver operating characteristic curves were calculated to verify the diagnostic value of DHL and ADD in predicting HO.

RESULTS

Both DHL and ADD were significantly larger in the HO group than in the non-HO group (P < 0.05). DHL ≥24.97% increased the risk of HO by 5 times (P = 0.003, 95% confidence interval 1.62-15.49), and ADD ≥36.67% increased the risk of HO by 3.87 times (P < 0.001, 95% confidence interval 1.81-8.27). A combined DHL and ADD (combined parameter) cutoff of 60.36 had a sensitivity of 87.18%, specificity of 67.35%, and area under the curve of 0.77 for predicting HO.

CONCLUSIONS

DHL and ADD are associated with the development of HO after CDR. The cutoff value of DHL may narrow the criteria for CDR with the aim of reducing HO formation. The combined parameter may help surgeons to select the most suitable implant height to reduce the prevalence of HO.

Dynamic foraminal dimensions during neck motion 6.5 years after fusion and artificial disc replacement

Objective

To compare changes in foraminal motion at two time points post-surgery between artificial disc replacement (ADR) and anterior cervical discectomy and fusion (ACDF).

Methods

Eight ACDF and 6 ADR patients (all single-level C5-6) were tested at 2 years (T1) and 6.5 years (T2) post-surgery. The minimum foraminal height (FH.Min) and width (FW.Min) achieved during neck axial rotation and extension, and the range of these dimensions during motion (FH.Rn and FW.Rn, respectively) were measured using a biplane dynamic x-ray system, CT imaging and model-based tracking while patients performed neck axial rotation and extension tasks. Two-way mixed ANOVA was employed for analysis.

Results

In neck extension, significant interactions were found between year post-surgery and type of surgery for FW.Rn at C5-6 (p<0.006) and C6-7 (p<0.005), and for FH.Rn at C6-7 (p<0.01). Post-hoc analysis indicated decreases over time in FW.Rn for ACDF (p<0.01) and increases in FH.Rn for ADR (p<0.03) at the C6-7 adjacent level. At index level, FW.Rn was comparable between ACDF and ADR at T1, but was smaller for ACDF than for ADR at T2 (p<0.002). In axial rotation, differences were found between T1 and T2 but did not depend on type of surgery (p>0.7).

Conclusions

Changes were observed in the range of foraminal geometry at adjacent levels from 2 years to 6.5 years post-surgery that were different between ACDF and ADR for neck extension. These changes are contrary to the notion that motion at adjacent levels continue to increase following ACDF as compared to ADR over the long term.

Anterior bone loss after cervical Bryan disc arthroplasty: insight into the biomechanics following total disc replacement

BACKGROUND CONTEXT

Cervical disc arthroplasty (CDA) is an innovative procedure launched in the early 2000s. Compared with anterior cervical discectomy and fusion, many studies show that CDA offers equivalent clinical outcomes while reducing secondary procedures and total cost.

PURPOSE

We sought to determine the incidence of anterior bone loss after CDA and the related biomechanical effects.

STUDY DESIGN/ SETTING

Retrospective chart review.

PATIENT SAMPLE

Patients who underwent CDA with one level Bryan Disc (Medtronic SofamorDanek, Memphis, TN, USA) at one institution.

OUTCOME MEASURES

Radiological measurements, including the extent of anterior bone loss, global alignment angle, shell angle, lordotic angle, mean degree of angle of the endplate with the horizontal line, global range of motion (ROM) and ROM of the index level were recorded. The grading of anterior bone loss of the index level was defined as Grade 0, no remodeling; Grade 1, spur disappearance or mild change in body contour; Grade 2, obvious bone regression with Bryan Disc exposure.

METHODS

Anatomical measures and ROM were compared by grade of bone loss.

RESULTS

Of the 121 patients included in the study, anterior bone loss was found in 53 (43.8%) on the upper adjacent level and 54 (44.6%) on the lower adjacent level. Twenty-nine patients (23.9%) had anterior bone loss in both levels. The majority of cases had Grade 1 anterior bone loss. Grade 2 bone loss was noted in the upper adjacent vertebra in only 5 patients and in 4 patients in the lower adjacent vertebra. Age, sex, operative level, and hybrid surgery had no effect on anterior bone loss. Most radiological assessments, including global alignment angle, lordotic angle, mean degree of angle of the endplate with the horizontal line, global ROM, and ROM of the index level, showed no correlation to anterior bone loss. Shell angle was found to be different in groups with or without remodeling in the upper adjacent level: 5.0 degreesin the Grade 0 group and 7.0 degrees in the Grade 1-2 group, p<.05.

CONCLUSIONS

Many more patients than predicted had anterior bone loss. Increasing the shell angle of the artificial disc may increase the incidence of anterior bone loss after CDA. Further study of the biomechanics following CDA should help clarify the mechanisms at work.

Total disc replacement compared with fusion for cervical degenerative disc disease: A systematic review of overlapping meta-analyses

STUDY DESIGN

The present study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement.

OBJECTIVE

The present study aimed to conduct a systematic review of overlapping meta-analyses comparing ACDR with fusion for treating CDDD in order to assist decision makers in their selection among conflicting meta-analyses and to provide treatment recommendations based on the best available evidence.

SUMMARY OF BACKGROUND DATA

Although several meta-analyses have been performed to compare total disc replacement (TDR) and fusion for treating cervical degenerative disc disease (CDDD), their findings are inconsistent.

METHODS

Multiple databases were comprehensively searched for meta-analyses comparing TDR with fusion for treating CDDD. The meta-analyses that comprised only randomized controlled trials (RCTs) were included. Two authors independently assessed the meta-analysis study quality and extracted the data. The Jadad decision algorithm was used to ascertain which meta-analysis studies represented the best evidence.

RESULTS

A total of 14 meta-analysis studies were included. All these studies only included RCTs and were determined as Level-II evidence.

CONCLUSIONS

Cervical disc arthroplasty was superior compared to anterior discectomy and fusion for the treatment of symptomatic cervical disc disease.

Finite element analysis of a ball-and-socket artificial disc design to suppress excessive loading on facet joints: A comparative study with ProDisc

Facet arthrosis at surgical level was identified as major complication after total disc replacement (TDR). One of the reasons for facet arthrosis after TDR has been speculated to be the hypermobility of artificial discs. Accordingly, the artificial disc that can constrain the hypermobility of ball-and-socket type artificial discs and reduce loading on facet joints is demanded. The proposed artificial disc, which is named as NewPro, was constructed based on the FDA-approved ProDisc but contained an interlocking system consisting of additional bars and grooves to control the range of motion (ROM) of lumbar spine in all anatomical planes. The three-dimensional finite element model of L1 to L5 was developed first, and the biomechanical effects were compared between ProDisc and NewPro. The ROM and facet contact force of NewPro were significantly decreased by 42.7% and 14% in bending and by 45.6% and 34.4% in torsion, respectively, compared with the values of ProDisc, thanks to the interlocking system. In addition, the ROM and facet contact force could be selectively constrained by modifying the location of the bars. The proposed artificial disc with the interlocking system was able to constrain the intersegmental rotation effectively and reduce excessive loading on facet joints, although wear and strength tests would be needed prior to clinical applications.

Total disc replacement versus fusion for lumbar degenerative diseases - a meta-analysis of randomized controlled trials

BACKGROUND

Lumbar fusion is considered to the gold standard for treatment of spinal degenerative diseases but results in adjacent segment degeneration and acquired spinal instability. Total disc replacement is a relatively new alternative avoiding the occurrence of the above complications. The systematic review and meta-analysis was designed to evaluate whether total disc replacement exhibited better outcomes and safety.

METHODS

PubMed, Web of Science, Embase, the Cochrane Library, Chinese National Knowledge Infrastructure Database(CNKI), Wangfang database, and VIP database were searched for RCTs comparing total disc replacement with lumbar fusion. All statistical analyses were carried out using the RevMan5.3 and STATA12.0 software.

RESULTS

Of 1116 citations identified by our search strategy, 14 RCTs met the inclusion criteria. Compared to lumbar fusion, total disc replacement significantly improved ODI, VAS, SF-36, patient satisfaction, overall success, reoperation rate, ODI successful, reduced operation time, shortened duration of hospitalization, decreased postsurgical complications. However, total disc replacement did not show a significant difference regarding blood loss, consumption of analgesics, neurologic success and device success with lumbar fusion. And charges were significantly lower for total disc replacement compared with lumbar fusion in the 1-level patient group, while charges were similar in the 2-level group.

CONCLUSION

Total disc replacement is recommended to alleviate the pain of degenerative lumbar diseases, improve the state of lumbar function and the quality of life of patients, provide a high level of security, have better health economics benefits for 1-level patients.

Superiority of 2-Level Total Disk Replacement Using a Cervical Disk Prosthesis Versus Anterior Cervical Diskectomy and Fusion

The purpose of this study was to evaluate the superiority of total disk replacement (TDR) using a cervical disk prosthesis vs anterior cervical diskectomy and fusion (ACDF). Ninety-six patients with a diagnosis of degenerative disk disease with radiculopathy or myeloradiculopathy at 2 contiguous levels from C-3 to C-7 were randomly allocated to the TDR group (n=48) or the ACDF group (n=48). Outcome measures were recorded preoperatively and 1 week and 3, 6, 12, 24, and 81 months postoperatively. A total of 80 patients completed the follow-up, including 38 in the TDR group and 42 in the ACDF group. Japanese Orthopaedic Association, visual analog scale, and Neck Disability Index scores showed statistically significant improvement from baseline in both groups. Moreover, compared with the TDR group, the ACDF group had statistically greater visual analog scale scores from 12 months and Neck Disability Index scores from 3 months. Compared with the ACDF group, the TDR group had statistically greater range of motion at both the superior and the inferior treated levels at 3, 6, 12, 24, and 81 months postoperatively. Compared with the TDR group, the ACDF group had statistically greater range of motion at the superior adjacent levels at 6, 12, 24, and 81 months and at the inferior adjacent levels at 24 and 81 months postoperatively. The occurrence of adjacent-segment degeneration at both the superior and the inferior adjacent levels was greater in the ACDF group than in the TDR group. Total disk replacement was safe and effective and a statistically superior alternative to ACDF for degenerative disk disease at 2 contiguous levels. It could reduce the occurrence of adjacent-segment degeneration at the superior and the inferior adjacent segments by reducing the range of motion. [Orthopedics. 2018; 41(6):344-350.].

Atypical symptoms in patients with cervical spondylosis: Comparison of the treatment effect of different surgical approaches

To compare the effectiveness of total disk replacement (TDR), anterior cervical discectomy and fusion (ACDF), and laminoplasty on atypical symptoms of cervical spondylosis.Patients with confirmed diagnosis of cervical spondylosis and reported atypical symptoms such as blurred vision, headache, nausea, palpitation, tinnitus, vertigo, hypomnesia, and abdominal discomfort were retrospectively included in the present study. They were treated with TDR, ACDF, or laminoplasty depending on the etiology and patient preference. Severity of the atypical symptoms before the surgery and at the end of 2-year follow-up was recorded and the degree of severity alleviation was compared between different surgical approaches.A total number of 336 patients who were treated in our institute from February 2002 to March 2011 were included in the final analysis. Atypical symptoms were significantly alleviated in most patients after surgical intervention. No significant differences were found regarding the change of severity of those symptoms among patients in different surgery groups.TDR, ACDF, and laminoplasty can equally alleviate the severity of atypical symptoms in patients with cervical spondylosis. This indicates that the neural network in the posterior longitudinal ligament may not be the cause of atypical symptoms in patients with cervical spondylosis.

Comparison of the adverse events of anterior cervical disc replacement versus anterior cervical discectomy and fusion: A protocol for a systematic review and meta-analysis of prospective randomized controlled trials

BACKGROUND

In the current surgical therapeutic regimen for symptomatic cervical degenerative disc disease, both anterior cervical discectomy and fusion (ACDF) and anterior cervical disc replacement (ACDR) are still widely accepted. However, many complications exist in both surgeries. Therefore, this study aims to compare the adverse events between ACDR and ACDF, and provide vital evidence-based guidance for spine surgeons and designers to evaluation of prognosis and improvement of dynamic devices.

METHODS

A systematic review and meta-analysis that will be performed according to the PRISMA. The electric database of PubMed, Medline, Embase, Google Scholar, and Cochrane library will be systematic search. A standard data form will be used to extract the data of included studies. We will assess the studies according to the Cochrane Handbook for Systematic Reviews of Interventions, and perform analysis in RevMan 5.3 software. Fixed effects models will be used for homogeneity data, while random-effects will be used for heterogeneity data. The overall effect sizes will be determined as weighted mean difference (WMD) for continuous outcomes and relative risk (RR) for dichotomous outcomes.

RESULT

The results of this study will be disseminated via international or national conferences, or submit to peer-reviewed journal in spinal field.

CONCLUSION

The conclusion of this study will provide key evidence-based guidance for spine surgeons and designers to the evaluation of prognosis and improvement of dynamic devices.

Intraoperative conversion of artificial cervical disc replacement to anterior cervical discectomy and fusion for iatrogenic fracture: A rare case report

RATIONALE

Artificial cervical disc replacement (ACDR) has been reported to be an effective and safe surgical treatment for cervical spondylosis. However, iatrogenic fracture during ACDR surgery has rarely been reported. Considering its infrequency, we report a rare clinical case, with the aim of sharing our experience and exploring when to convert ACDR to fusion intraoperatively.

PATIENTS CONCERNS

A 47-year-old woman felt neck pain with weakness and numbness in both upper limbs for 5 months.

DIAGNOSES

The patient had received discectomy and fusion procedure on C3/4 and C5/6 to relieve her radicular pain nearly 4 years prior. Neurologic examination revealed a diminished sensation at the C6-C8 skin areas and level Grade-4 power in the left wrist extensor and grip muscle strength. Magnetic resonance imaging (MRI) showed disc herniation compressing the spinal cord at C6/7. Computed tomography (CT) scans showed intervertebral fusion in both the C3/4 and C5/6 segments.

INTERVENTIONS

Surgery was performed to remove the plate and replace C6/7 with an artificial disc, but a transverse cleavage endplate cortical fracture was detected after cutting the blades. Thus, we terminated artificial cervical disc replacement intraoperatively and changed to discectomy and fusion in C6/7.

OUTCOMES

The patient's symptoms were remarkably relieved. Postoperative CT scans showed a transverse cleavage fracture in the backside of the C6 caudal endplate. Good fusion was achieved after 6 months.

LESSONS

Iatrogenic fracture during ACDR is rare but does occur in clinic practice. Complete examination and an alternative approach determined before surgery are important for operative safety. Anterior cervical discectomy and fusion (ACDF) is recommended as a feasible remedial surgical strategy if ACDR fails intraoperatively.

What's the best surgical treatment for patients with cervical radiculopathy due to single-level degenerative disease? A randomized controlled trial

Background

To investigate the efficacy of adding supplemental fusion or arthroplasty after cervical anterior discectomy for symptomatic mono-level cervical degenerative disease (radiculopathy), which has not been substantiated in controlled trials until now.

Methods

A randomized controlled trial is reported with 9 years follow up comparing anterior cervical anterior discectomy without fusion, with fusion by cage standalone, or with disc prosthesis. Patients suffering from symptomatic cervical disk degeneration at one level referred to spinal sections of department of neurosurgery or orthopedic surgery of a large general hospital with educational facilities were eligible. Neck Disability Index (NDI), McGill Pain Questionnaire Dutch language version (MPQ-DLV), physical-component summary (PCS), and mental-component summary (MCS) of the 36-item Short-Form Health Survey (SF-36), and re operation rate were evaluated.

Findings

142 patients between 18 and 55 years were allocated. The median follow-up was 8.9±1.9 years (5.6 to 12.2 years). The response rate at last follow-up was 98.5%. NDI at the last follow-up did not differ between the three treatment groups, nor did the secondary outcomes as MPQ-DLV and PCS or MCS from SF-36. The major improvement occurred within the first 6 weeks after surgery. Afterward, it remained stable. Eleven patients underwent surgery for recurrent symptoms and signs due to nerve root compression at the index or adjacent level.

Conclusions

This randomized trial could not detect a difference between three surgical modalities for treating a single-level degenerative disk disease. Anterior cervical discectomy without implant seems to be similar to anterior cervical discectomy with fusion by cage stand-alone or with disk prosthesis. Due to the small study sample size, this statement should be considered as inconclusive so far.

Trial registration

ISRCTN41681847

The prevalence of heterotopic ossification among patients after cervical artificial disc replacement: A systematic review and meta-analysis

BACKGROUND

Prevalence estimates of heterotopic ossification (HO) following cervical artificial disc replacement (ADR) varied widely in previous studies. We conducted a systematic review and meta-analysis to summarize its point prevalence.

METHODS

Electronic searches of PubMed, Web of Science, Embase, and Cochrane Library databases were conducted to identify studies that reported prevalence of HO. Definitions of HO and severe HO were based on McAfee grading system. Random-effects model was used to estimate the pooled prevalence. We conducted subgroup analyses according to the different length of follow-up time, and performed univariate metaregression analyses to explore the effects of potential variables on the overall prevalence.

RESULTS

A total of 38 studies were included in this study. The pooled data showed that the prevalence of HO after cervical ADR within the 1 to 2 years, 2 to 5 years, and 5 to10 years of follow-up was 38.0% (95% confidence interval [CI], 30.2%-46.5%), 52.6% (95% CI, 43.1%-61.9%), and 53.6% (95% CI, 40.0%-66.7%), respectively, while the prevalence of severe HO was 10.9% (95% CI, 9.0%-13.2%), 22.2% (95% CI, 15.5%-30.7%), and 47.5% (95% CI, 30.0%-65.8%), respectively. Follow-up time was positively associated with the prevalence of severe HO (P < .01), and the 1-month growth of mean follow-up went with 0.63% increase of severe HO.

CONCLUSION

This meta-analysis reported data on the prevalence of HO and severe HO after cervical ADR, and provided information on its process of development. These should be useful to enable surgeons and patients to gain a better understanding of HO after cervical ADR.

Periprosthetic UHMWPE Wear Debris Induces Inflammation, Vascularization, and Innervation After Total Disc Replacement in the Lumbar Spine

BACKGROUND

The pathophysiology and mechanisms driving the generation of unintended pain after total disc replacement (TDR) remain unexplored. Ultrahigh-molecular-weight polyethylene (UHMWPE) wear debris from TDRs is known to induce inflammation, which may result in pain.

QUESTIONS/PURPOSES

The purpose of this study was to determine whether (1) periprosthetic UHMWPE wear debris induces immune responses that lead to the production of tumor necrosis factor-α (TNFα) and interleukin (IL)-1ß, the vascularization factors, vascular endothelial growth factor (VEGF) and platelet-derived growth factor-bb (PDGFbb), and the innervation/pain factors, nerve growth factor (NGF) and substance P; (2) the number of macrophages is associated with the production of the aforementioned factors; (3) the wear debris-induced inflammatory pathogenesis involves an increase in vascularization and associated innervation.

METHODS

Periprosthetic tissues from our collection of 11 patients with contemporary TDRs were evaluated using polarized light microscopy to quantify UHMWPE wear particles. The major reason for revision (mean implantation time of 3 years [range, 1-6 years]) was pain. For control subjects, biopsy samples from four patients with degenerative disc disease with severe pain and autopsy samples from three normal patients with no history of back pain were also investigated. Immunohistochemistry and histology were used to identify secretory factors, macrophages, and blood vessels. Immunostained serial sections were imaged at ×200 magnification and using MATLAB and NIH ImageJ, a threshold was determined for each factor and used to quantify positive staining normalized to tissue sectional area. The Mann-Whitney U test was used to compare results from different patient groups, whereas the Spearman Rho test was used to determine correlations. Significance was based on p < 0.05.

RESULTS

The mean percent area of all six inflammatory, vascularization, and innervation factors was higher in TDR tissues when compared with normal disc tissues. Based on nonparametric data analysis, those factors showing the most significant increase included TNFα (5.17 ± 1.76 versus 0.05 ± 0.03, p = 0.02), VEGF (3.02 ± 1.01 versus 0.02 ± 0.002, p = 0.02), and substance P (4.15 ± 1.01 versus 0.08 ± 0.04, p = 0.02). The mean percent area for IL-1ß (2.41 ± 0.66 versus 0.13 ± 0.13, p = 0.01), VEGF (3.02 ± 1.01 versus 0.34 ± 0.29, p = 0.04), and substance P (4.15 ± 1.01 versus 1.05 ± 0.46, p = 0.01) was also higher in TDR tissues when compared with disc tissues from patients with painful degenerative disc disease. Five of the factors, TNFα, IL-1ß, VEGF, NGF, and substance P, strongly correlated with the number of wear particles, macrophages, and blood vessels. The most notable correlations included TNFα with wear particles (p < 0.001, ρ = 0.63), VEGF with macrophages (p = 0.001, ρ = 0.71), and NGF with blood vessels (p < 0.001, ρ = 0.70). Of particular significance, the expression of PDGFbb, NGF, and substance P was predominantly localized to blood vessels/nerve fibers.

CONCLUSIONS

These findings indicate wear debris-induced inflammatory reactions can be linked to enhanced vascularization and associated innervation/pain factor production at periprosthetic sites around TDRs. Elucidating the pathogenesis of inflammatory particle disease will provide information needed to identify potential therapeutic targets and treatment strategies to mitigate pain and potentially avoid revision surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Cervical disc replacement - emerging equivalency to anterior cervical discectomy and fusion

PURPOSE

Cervical disc replacement has become an acceptable alternative to anterior cervical fusion for the surgical treatment of cervical spine spondylosis resulting in radiculopathy or myelopathy following anterior discectomy and decompression. This concise overview considers the current state of knowledge regarding the continued debate of the role of cervical disc replacement with an update in light of the latest clinical trial results.

METHODS

A literature review was performed identifying clinical trials pertaining to the use of cervical disc replacement compared to cervical discectomy and fusion. Single level disease and two level disease were considered. Outcome data from the major clinical trials was reviewed and salient points identified.

RESULTS

With lengthier follow-up data becoming available, the equivalence of CDR in appropriately selected cases is becoming clear. This is chiefly manifested by reduced re-operation rates and reduced incidence of adjacent level disease in those treated with arthroplasty.

CONCLUSION

Cervical disc replacement shows emerging equivalence in outcomes compared to the gold standard anterior cervical discectomy and fusion. Further longer term results are anticipated to confirm this trend.

[Not Available]

Chronic low back pain is extremelyfrequent and its management is still con troversial among spine physicians. For decades, intervertebral fusion has been considered as the gold- standard. However, non fusion techniques have been developed in order to avoid fusion's complications. Numerous studies have reported satisfactory results of total disc arthro- plasty in the management of lumbar degenerative disc disease. So far it is still dificult to prove the superiority of disc replacement over fusion due to a lack of high level studies. The aim of this work was to try to answers various questions related to that technique which was described twenty years ago.

[Complications of cervical artificial disc replacement]

Cervical artificial disc replacement (CADR) as a new method for the treatment of cervical spondylosis, is becoming a basic and clinical research. Compared with the anterior cervical discectomy and fusion (ACDF), the biggest difference of CADR lies in the reconstruction of the cervical vertebra height and physiological curvature, retaining the spinal physiological function maximally and reducing the degenerative changes in adjacent segments. A large number of clinical investigation have suggested that ACDR can become an operation method to replace the ACDF. However, the complications and the problems of prosthesis itself are gradually exposed, such as that the prosthesis, can't completely simulate the biological effects of human intervertebral disc, the other factors and including the operation methods and prosthesis itself. At the same time, the problem that how to prevent complications and problems is required to be solved. Whether, the effect of CADR on the activity of the operation segment, and the prevention of adjacent segment degeneration can be guaranteed for a long time has drawn more and more attention from scholars.

Quality of systematic reviews: an example of studies comparing artificial disc replacement with fusion in the cervical spine

Cervical artificial disc replacement (C-ADR) is now an alternative to anterior cervical discectomy and fusion (ACDF). Many studies have evaluated the efficacy of C-ADR compared with ACDF. This led to a series of systematic reviews and meta-analyses to evaluate the evidence of the superiority of one intervention against the other. The aim of the study presented here was to evaluate the quality of these reviews and meta-analyses. Medline via Ovid, Embase, and Cochrane Library were searched using the keywords: (total disk replacement, prosthesis, implantation, discectomy, and arthroplasty) AND (cervical vertebrae, cervical spine, and spine) AND (systematic reviews, reviews, and meta-analysis). Screening and data extraction were conducted by two reviewers independently. Two reviewers then assessed the quality of the selected reviews and meta-analysis using 11-item AMSTAR score which is a validated measurement tool to assess the methodological quality of systematic reviews. Screening of full reports of 46 relevant abstracts resulted in the selection of 15 systematic reviews and/or meta-analyses as eligible for this study. The two reviewers' inter-rater agreement level was high as indicated by kappa of >0.72. The AMSTAR score of the reviews ranged from 3 to 11. Only one study (a Cochrane review) scored 100% (AMSTAR 11). Five studies scored below (AMSTAR 5) indicating low-quality reviews. The most significant drawbacks of reviews of a score below 5 were not using an extensive search strategy, failure to use the scientific quality of the included studies appropriately in formulating a conclusion, not assessing publication bias, and not reporting the excluded studies. With a significant exception of a Cochrane review, the methodological quality of systematic reviews evaluating the evidence of C-ADR versus ACDF has to be improved.

Minimum 4-year outcomes of cervical total disc arthroplasty versus fusion: a meta-analysis based on prospective randomized controlled trials

The prevalence of cervical disc disease is high, and the traditional surgical method of anterior cervical discectomy and fusion (ACDF) carries with it the disadvantages of motion loss at the operated level, and accelerated adjacent level disc degeneration. Preliminary results of the efficacy and reoperative rate comparing TDA versus ACDF have been reported; however, the long-term outcomes of TDA versus ACDF still remain a topic of debate. This review was prepared following the standard procedures set forth by the Cochrane Collaboration organization, and preferred reporting items for systematic reviews and meta-analyses (PRISMA). The only studies included were randomized controlled trials with a minimum of 4 years of follow-up data. The meta-analysis included the neck disability index (NDI), visual analog scale (VAS) of neck and arm pain, SF-36 physical component scores (SF-36 PCS), over success, neurological success, work status, implant-related complications, and secondary surgery events. Four randomized controlled trials meet the inclusion criteria. The long-term improvement of NDI, VAS of neck and arm pain, SF-36 PCS, over success, and neurological success favored the TDA group. The TDA group also had a lower incidence of secondary surgery for both the index level (RR: 0.45 [0.28, 0.72]) and adjacent level (RR: 0.53 [0.33, 0.88]). In this meta-analysis of 4 included RCTs with a minimum 4 years of follow-ups, total disc arthroplasty showed improvements over ACDF as measured by the NDI, VAS of neck and arm pain, and SF-36 PCS.

A prospective, randomised, controlled multicentre study comparing cervical disc replacement with anterior cervical decompression and fusion

PURPOSE

Total cervical artificial disc replacement (TDR) simulates normal disc structure, thus avoiding the drawbacks of anterior cervical decompression and fusion (ACDF). This prospective, randomized, controlled and multicentre study aimed to evaluate clinical and radiographic outcomes by comparing cervical disc replacement using Mobi-C disc prostheses with ACDF.

METHODS

This prospective, randomized, controlled and multicentre study consisted of 111 patients undergoing single-level Mobi-C disc prosthesis replacement (TDR group, n = 55) or ACDF (n = 56) from February 2008 to November 2009 at 11 medical centres across China. Patients were assessed before surgery, at seven days postoperation and one, three, six, 12, 24, 36 and 48 months postoperation. Clinical and neurological outcome was determined by measuring the Japanese Orthopaedic Association (JOA) scores, visual analogue scale (VAS) and Neck Disability Index (NDI). Static and dynamic radiographs were obtained of the cervical curvature, the functional spinal unit (FSU) angle and range of motion (ROM) of the cervical spine, FSU angle and treated and adjacent segments.

RESULTS

A total of 111 patients were included and randomly assigned to either Mobi-C disc prosthesis replacement or ACDF. JOA, VAS and NDI showed statistically significant improvements 48 months after surgery (P < 0.05). ROM, FSU angle, treated segment and adjacent segments in the Mobi-C group were not significantly different before and after replacement (p > 0.05). ROM in the ACDF group was significantly reduced at one month and remained so throughout the follow-up. By 48-months, more ACDF patients required secondary surgery (four of 56 patients).

CONCLUSIONS

Although ACDF may increase the risk of additional surgery, clinical outcomes indicated that both Mobi-C artificial cervical disc replacement and ACDF were reliable. Radiographic data showed that ROM of the cervical spine, FSU angle and treated and adjacent segments were relatively better reconstructed and maintained in the Mobi-C group compared with those in the ACDF group.

Double-level cervical total disc replacement for adjacent segment disease: is it a useful treatment? Description of late onset heterotopic ossification and review of the literature

We report a rare case of double-level adjacent segment disease (ASD), occurring ten years later an anterior cervical discectomy (ACD) without fusion, treated by cervical arthroplasty, highlighting the outcome at long-term follow-up and focusing on heterotopic ossification. In 1995 a 25-year-old man satisfactorily underwent ACD at C4/C5. At that time MRI also showed signs of degenerative disc disease (DDD) at C3/C4 and C5/C6. Ten years later, a new MRI scan showed a large C3/C4 and a smaller C5/C6 soft disc hernia together with spondylotic changes at the level above and below the site of the first surgery. At C4/C5 imaging revealed a kyphotic stable "pseudoarthrosis" with anterior bridging osteophyte. The patient underwent double-level arthroplasty with ProDisc-C. Clinical and radiological outcome was satisfactory. 3 and 5 years after surgery, X-rays and CT scan documented the progressive development of heterotopic ossification, with gradual reduction of range of motion. A late onset heterotopic ossification can neutralize the theoretical advantages of cervical arthroplasty, which should be considered an effective surgical option only in selected cases. ACDF and restoration of normal lordosis can be a viable alternative in cervical revision surgery, as motion preservation can not be always mantained for a long time.

Adverse events recording and reporting in clinical trials of cervical total disk replacement

Adverse events reporting in pivotal trials of new technologies, such as cervical total disk replacement, are essential to determine safety. Important questions concerning the adequacy of reporting about such new technologies in peer-reviewed publications have prompted this analysis to assess the safety of cervical disk replacement compared with fusion as presented in peer-reviewed publications and FDA summary reports. Identifying differences among these reports highlight the poor quality of adverse event reporting in the peer-reviewed literature. Nine peer-reviewed studies and five FDA summary reports documented excellent safety for both cervical fusion and disk arthroplasty. No differences in rates of adverse events were found to exist between the two treatments. The methods of recording and the actual reporting of adverse events were poor in peer-reviewed manuscripts, whereas they were comprehensive but difficult to clinically apply in the FDA summaries. Recommendations to improve documentation and reporting of adverse events are presented.

Incidence and risk factors analysis of heterotopic ossification after cervical disc replacement

BACKGROUND

Cervical disc replacement (CDR) as a substitute for traditional fusion surgery has been widely used in treating degenerative cervical disc diseases. The objectives of this study were to assess the clinical and radiological findings for patients with heterotopic ossification (HO) following CDR and to detect the risk factors of HO after CDR.

METHODS

A total of 125 patients with symptomatic cervical single- or double-level disc diseases, who underwent CDR procedure with Discover prosthesis in Department of Spine Surgery, Changzheng Orthopedics Hospital from March 2009 to March 2011, were enrolled in this retrospective study. Occurrence of HO was defined by the McAfee classification on cervical lateral X-rays in this study. Prosthesis vertebral ratio (PVR) was used to determine the matching degree between the cervical disc prosthesis and cervical vertebra. Logistic regression analyses were performed to determine the risk factors of HO. Variables evaluated for their association with HO occurrence included age, gender, high-intensity signal in spinal cord, preoperative range of motion (ROM), postoperative ROM, operation level number, and PVR.

RESULTS

Mean follow-up time was (26.4±5.8) months. All the patients had significant symptoms and neurological function improvements during the follow-up period. The ROM of the operated segment from the preoperative period to the last follow-up was relatively well maintained. The rate of HO in this cohort of patients, who underwent Discover disc, was 27.92% per surgical level and 24.8% per patient by the last follow-up. There were 19 patients (19.79%) with HO in the single-level group while 12 patients (41.38%) in the double-level group.

CONCLUSIONS

We identified preoperative high-intensity signal in spinal cord, postoperative ROM of surgical level, number of operation level, and PVR as significant risk factors for postoperative HO occurrence.

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.

Parameters influencing the outcome after total disc replacement at the lumbosacral junction. Part 1: misalignment of the vertebrae adjacent to a total disc replacement affects the facet joint and facet capsule forces in a probabilistic finite element analysis

PURPOSE

After total disc replacement with a ball-and-socket joint, reduced range of motion and progression of facet joint degeneration at the index level have been described. The aim of the study was to test the hypothesis that misalignment of the vertebrae adjacent to the implant reduces range of motion and increases facet joint or capsule tensile forces.

METHODS

A probabilistic finite element analysis was performed using a lumbosacral spine model with an artificial disc at level L5/S1. Misalignment of the L5 vertebra, the gap size of the facet joints, the transection of the posterior longitudinal ligament, and the spinal shape were varied. The model was loaded with pure moments.

RESULTS

Misalignment of the L5 vertebra reduced the range of motion up to 2°. A 2-mm displacement of the L5 vertebra in the anterior direction already led to facet joint forces of approximately 240 N. Extension, lateral bending, and axial rotation caused maximum facet joint forces between 280 and 380 N, while flexion caused maximum forces of approximately 200 N. A 2-mm displacement in the posterior direction led to capsule forces of approximately 80 N. Additional moments increased the maximum facet capsule forces to values between 120 and 230 N.

CONCLUSIONS

Misalignment of the vertebrae adjacent to an artificial disc strongly increases facet joint or capsule forces. It might, therefore, be an important reason for unsatisfactory clinical results. In an associated clinical study (Part 2), these findings are validated.

[Curative effect evaluation and complication analysis of Bryan artificial cervical disc replacement]

OBJECTIVE

To observe the curative effects and complications of Bryan cervical disc replacement for cervical disc herniation.

METHODS

From Jannary 2005 to December 2008,39 patients with cervical disc herniation were treated with Bryan cervical disc replacement. There were 20 males and 19 females,with an average age of 47 years old (ranged, 35 to 59). Spinal compression symptom (20 cases) and nerve root symptom (19 cases) were main clinical symptoms. Single level disc was replaced in 35 cases and two-level replaced in 4 cases. Offset and activity of prosthesis,cervical physiological curvature, heterotopic ossification, prosthetic fusion were observed by dynamic X-ray. According to Odom's standard and JOA score,nerve function were evaluated; and depending on NDI standard,clinical symptom and daily function status were recorded.

RESULTS

All the patients were followed up from 16 to 36 months with an average of 24 months. Nerve function obviously improved and radiating pain of upper limb completely relieved. No patient with prosthetic anterior-posterior offset more than 2 mm was found. Prosthetic flexion and extention angle was (8.5+-1.8)degrees,left and right flexion range respectively were (3.5+/-1.2)degrees and (3.3+/-1.5)degrees. Cervical physiological curvature improved obviously or recovered normally. Three cases occurred in heterotopic ossification and 2 cases occurred in prosthetic fusion. According to Odom's standard,25 cases got an excellent results,9 good, 5 fair, the rate of excellent and good was 87.2%. JOA score increased from preoperative (8.26+/-1.32) to (15.71+/-1.89) at final follow-up and NDI decreased from preoperative (43.7+/-3.8) to (20.1+/-2.9) at final follow-up.

CONCLUSION

Treatment of cervical disc herniation with Bryan cervical disc replacement can get the good curative effects,which can obtain good nerve functional recovery,cervical stability and activity. Nevertheless,the operation has typical complication such as heterotopic ossification and prosthetic fusion. Thus,it is important in chosing indication and operative procedure.

The risk of adjacent-level ossification development after surgery in the cervical spine: are there factors that affect the risk? A systematic review

STUDY DESIGN

Systematic review.

OBJECTIVE

To answer the following clinical questions: (1) What is the risk of adjacent-level ossification development (ALOD) in patients receiving noninstrumented cervical fusion, instrumented cervical fusion with a plate, or cervical total disc arthroplasty?; (2) What are the risk factors for ALOD?; (3) What is the time course for the development of ALOD?; and (4) Does ALOD affect outcomes and rates of reoperation?

SUMMARY OF BACKGROUND DATA

Anterior cervical plating, total disc arthroplasty, and noninstrumented fusion have all been used in the treatment of cervical disc disease. There are numerous reports that identify ALOD, a form of heterotopic ossification, as a major risk factor after performing these procedures. Few studies have compared these 3 procedures to evaluate the risk, timing, and outcomes related to postoperation ALOD.

METHODS

A systematic search was conducted in PubMed and the Cochrane Library for articles published between January 1, 1990, and December 31, 2011. We included all articles that described the risk of or risk factors for ALOD after surgical treatment of the cervical spine. Studies with patients older than 18 years or those treated for tumor or trauma were excluded from the study. In addition, those with posterior fusions, case reports, and case series with less than 10 patients were excluded.

RESULTS

A total of 5 studies met the inclusion criteria for our systematic review. The risk of ALOD with anterior cervical discectomy and fusion ranged from 41% to 64%, whereas the risk of ALOD after total disc replacement ranged from 6% to 24%. When ALOD did occur, there was a 2-fold higher risk of development at the cranial adjacent segment. The most important risk factor for the development of ALOD was the use of instrumentation and the plate-to-disc distance, although the surgical procedure type (corpectomy vs. discectomy and fusion) neared but did not reach statistical significance. Insufficient evidence was available to delineate the time course for its development and how ALOD affected outcomes.

CONCLUSION

The current body of literature suggests that ALOD will develop with the use of instrumentation and especially so if anterior instrumentation is placed within 5 mm of the adjacent cranial disc segment. In addition, total disc replacement showed lower rates for the development of ALOD compared with anterior cervical discectomy and fusion at both short- and long-term follow-up.

CONSENSUS STATEMENT

We recommend that the surgeon make every effort to keep the plate as far away from the adjacent disc as possible. Strength of Statement: Strong.

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.

[Analysis of effectiveness and incidence of heterotopic ossification after single-level Bryan cervical artificial disc replacement]

OBJECTIVE

To evaluate the incidence of heterotopic ossification (HO) after single-level Bryan cervical artificial disc replacement, and to identify the relationship between HO and the effectiveness.

METHODS

The clinical data of 48 patients undergoing single-level Bryan cervical artificial disc replacement between October 2005 and October 2007 were reviewed retrospectively. There were 27 males and 21 females with an average age of 40.5 years (range, 33-51 years), including 8 cases of cervical myelopathy, 27 cases of nerve root cervical spondylosis, and 13 cases of mixed cervical spondylosis with an average disease duration of 10.3 months (range, 2-14 months). The involved segments included C3,4 in 3 cases, C4,5 in 6 cases, C5,6 in 30 cases, and C6,7 in 9 cases. The outcomes were evaluated using Visual Analogue Scale (VAS) score, the neck disability index (NDI), and cervical range of motion (ROM). According to patients with or without HO, 48 patients were divided into 2 groups (HO group and no HO group). VAS score, NDI, and cervical ROM were compared between 2 groups at 1, 2, 3, and 4 years after operation.

RESULTS

No severe complication occurred during and after operation in all patients. Forty-eight patients were followed up 48-72 months (mean, 56.6 months). VAS score and NDI were significantly improved when compared with preoperative values at all time points (P < 0.05); except at 3 days after operation, no significant difference was found in cervical ROM at the other time points when compared with preoperation (P > 0.05). Thirteen patients (27.08%) had HO at 4 years after operation, including 8 cases of grade 1, 3 cases of grade 2, and 2 cases of grade 3. There was no significant difference in VAS score, NDI, and cervical ROM between 2 groups at 1, 2, 3, and 4 years (P > 0.05).

CONCLUSION

The incidence of HO after single-level Bryan cervical artificial disc replacement is relatively high. However, HO has no effect on the cervical ROM and the effectiveness.

Persistent pain following lumbar disc replacement

BACKGROUND

Pain patterns associated with the facet and sacroiliac joints following lumbar total disc replacement correlate with biomechanical modeling observations, such as load transfer to the posterior spinal elements in total disc replacement with an artificial disc. When conventional treatment options are exhausted, spinal cord stimulation (SCS) offers clinically favorable outcomes to treat intractable pain.

OBJECTIVES

To contribute to the literature on neuroaugmentive techniques and on pain following disc replacement, and to highlight recent advances and forward-thinking concepts for nonsurgical intradiscal therapies.

RESULTS

Three years of injection therapies and physical therapy did not significantly alleviate the patient's pain. A trial period of SCS rather than reoperation (fusion surgery) was elected. A constant-current multiple source SCS system was implanted. At 12-month follow-up for this system, the patient's pain had been reduced by more than 75%, and the patient reported improved quality of life, including a return of restful sleep.

CONCLUSIONS

SCS is a viable technique to control pain associated with artificial disc implant.

The incidence of adjacent segment degeneration after cervical disc arthroplasty (CDA): a meta analysis of randomized controlled trials

Background

Cervical disc arthroplasty is being used as an alternative degenerative disc disease treatment with fusion of the cervical spine in order to preserve motion. However, whether replacement arthoplasty in the spine achieves its primary patient centered objective of lowering the frequency of adjacent segment degeneration is not verified yet.

Methodology

We conducted a meta-analysis according to the guidelines of the Cochrane Collaboration using databases including PubMed, Cochrane Central Register of Controlled Trials and Embase. The inclusion criteria were: 1) Randomized, controlled study of degenerative disc disease of the cervical spine involving single segment or double segments using Cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) as controls; 2) A minimum of two-year follow-up using imaging and clinical analyses; 3) Definite diagnostic evidences for “adjacent segment degeneration” and “adjacent segment disease”; 4) At least a minimum of 30 patients per population. Two authors independently selected trials; assessed methodological quality, extracted data and the results were pooled.

Results

No study has specifically compared the results of adjacent segment degenerative; Two papers describing 140 patients with 162 symptomatic cervical segment disorders and compared the rate of postoperative adjacent segment disease development between CDA and ACDF treatments, three publications describing the rate of adjacent-segment surgery including 1273 patients with symptomatic cervical segments. The result of the meta-analysis indicates that there were fewer the rate of adjacent segment disease and the rate for adjacent-segment surgery comparing CDA with ACDF, but the difference was not statistically significant.

Conclusions

Based on available evidence, it cannot be concluded, that CDA can significantly reduce the postoperative rate of the adjacent segment degenerative and adjacent segment disease. However, due to some limitations, the results of this meta-analysis should be cautiously accepted, and further studies are needed.

[ProDisc-C Total Disc Replacement. A four-year prospective monocentric study]

PURPOSE OF THE STUDY

To present the results of an independent prospective monocentric study of patients with ProDisc-C Total Disc Replacement (CTDR) followed up for 4 years, and to analyse the most frequent late complications, in particular heterotopic ossification.

MATERIAL

In the period from October 2004 to May 2006, a total of 61 patients underwent ProDisc-C CTDR involving one or two segments at the Department of Spinal Surgery, University Hospital in Motol. This study included 39 patients who were followed up for at least 4 years. With the exception of one patient operated on two segments, the patients were treated by ProDisc-C CTDR at one level.

METHODS

In the study, only the surgical procedure recommended by the implant manufacturer (Synthes, USA) was used and all operations were performed by a team with the same leading surgeon. Clinical assessment. The patients were examined before surgery, immediately after it and at 6 and 12 weeks and 6, 12, 24 and 48 months post-operatively. At each follow-up, responses to the questionnaire were obtained, and the patients' health status was evaluated on the basis of Neck Disability Index (NDI) and Visual Analogue Score (VAS) values for cervical spine and radicular pain, the use of analgesics and personal satisfaction Radiographic assessment. Pre- and post-operative radiographs were taken in antero-posterior and lateral projection, and flexion, extension and lateral bending films were obtained The height of the intervertebral disc space at the affected level was measured and range of motion in flexion and extension was evaluated together with the adjacent levels. In addition, subsidence, loosening, failure or displacement of the implant was assessed, as well as the presence of heterotopic ossification. The results were statistically analysed using Student's t-test.

RESULTS

The clinical results at 1, 2 and 4 years of follow-up were as follows: NDI values, 44.9 pre-operatively, 26.1, 25.8 and 25.1 post-operatively, improvement by 44.1% after 4 years; VAS for cervical spine pain, 5.8 pre-operatively, 3.0, 2.7 and 2.7 postoperatively, improvement after 4 years by 53.7%; VAS for radicular pain, 6.3 pre-operatively, 2.9, 2.9 and 2.7 postoperatively, improvement by 57.1% after 4 years. The radiographic findings showed the average intervertebral disc space height of 3.2 mm at the affected level before and 7.4 mm after surgery, with no significant change in the following period. The average range of disc motion at the affected level was 4.2 degrees before and 11.1 degrees after surgery, with 11.4 degrees at 4 years of follow-up. During that period, heterotopic ossification was recorded in 10 (25%) treated discs, with five of them (12.5%) classified as grade III or IV. Spontaneous fusion across the disc replacement level was found in three cases (7.5%). Two patients (5%) developed kyphosis at the affected disc level. The statistical analysis showed a significant difference between the pre-operative VAS values and those at 6 post-operative weeks for both cervical spine and radicular pain (t = 4.4 and t = 5.3, respectively; p < 0.05). No significant difference in VAS values was found between 6 weeks and 3 months after surgery for either condition (t = 1.69 and t = 0.3; p > 0.05). Changes in VAS values in the following period were minimal and non-significant. The differences in NDI values before surgery and at 6 weeks after it, and between 6 weeks and 3 months post-operatively were significant (t = 11, p < 0.05 and t = 3.8, p < 0.05, respectively). In the following period, changes in the values were minimal and non-significant.

DISCUSSION

Short-term studies on various types of cervical disc replacement have been optimistic and reported good clinical results and few complications. However, with longer follow-ups there has been an increasing incidence of heterotopic ossification as the most frequent late complication. Although the number of patients diagnosed with it is growing, heterotopic ossification influences the patient's clinical problems only little. What are its causes and how to prevent it are questions to be fully answered yet

CONCLUSIONS

Heterotopic ossification is the most frequent late complication of total disc replacement. Many factors may be responsible for its development and therefore its prevention is not clear. The correct indication and appropriate surgical technique are most often recommended, and are considered also by the authors to be most important. Restricted motion at the treated segment/s has no significant effect on the patient's clinical status.