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.

Substantial clinical benefit for Neck Disability Index revisited: establishing the goal for treatment?

PURPOSE: It is difficult for clinicians to inform patients about the success rate of a treatment as a cervical anterior discectomy procedure. Ideally, a proportion of good outcome as rated by patients is known. Patient-reported outcome measurements are helpful. The purpose is to relate the difference in Neck Disability Index (NDI) after a cervical anterior discectomy procedure for single level cervical degenerative disc disease with the patients' rating of their actual clinical situation after long-term follow-up to define the substantial clinical benefit (SCB). METHODS: After completion of the NDI, patients who were surgically treated for cervical single level degenerative disease were asked to complete a five-item Likert scale to rate their clinical situation. After dichotomisation of the outcome in good versus less than good, a cut-off value was defined by determining the value of the difference of NDI with the highest specificity and sensitivity. Funding was not obtained. RESULTS: SCB for NDI after surgery for cervical single level degenerative disease should be set at ten with area under the curve (AUC) of 0.71 for sensitivity as well specificity. CONCLUSIONS: The goal for each treatment is a good outcome. While comparing treatments for cervical degenerative disc disease only those with an SCB of ten will be relevant for the patient, as patients who achieved this difference in NDI rated their actual situation at long-term follow-up as good.

Symptomatic Adjacent Segment Disease After Anterior Cervical Discectomy for Single-level Degenerative Disk Disease.

STUDY DESIGN: A prospective cohort of 142 patients underwent either anterior cervical discectomy alone, anterior cervical discectomy with fusion by cage stand-alone, or anterior cervical discectomy with arthroplasty. We then followed up on their condition for a mean of 9.1±1.9 years (5.6-12.2 y) later. OBJECTIVE: We aimed to evaluate the annual rate of clinically symptomatic adjacent segment disease (ASD) and to analyze predictive factors. SUMMARY OF BACKGROUND DATA: Until recent, ASD has been predominantly evaluated radiologically. It is not known whether all patients had complaints. A frequent cited annual rate of ASD is 2.9%, but a growing number of studies report a lower annual rate. Furthermore, maintaining motion to prevent ASD is one reason for implanting a cervical disk prosthesis. However, the results of studies contradict one another. METHODS: Participants took part in a randomized controlled trial that ended prematurely because of the publication of evidence that did not justify continuation of the trial. The patients were randomly allocated to 3 groups, each of which received one of the abovementioned treatments. We defined symptomatic ASD as signs and symptoms caused by degeneration of an intervertebral disk adjacent to a level of previous anterior cervical disk surgery. At the last follow-up, we were able to ascertain whether clinically symptomatic ASD was present in any of the participants. RESULTS: The overall annual rate of symptomatic ASD was 0.7%. We found no statistically significant correlations between any of the investigated factors and symptomatic ASD except for the surgical method used. Symptomatic ASD was seen less often in anterior cervical discectomy solely or anterior cervical discectomy with arthroplasty than in anterior cervical discectomy with fusion by plate fixation. CONCLUSIONS: The annual rate of symptomatic ASD after an anterior cervical discectomy procedure was estimated to be 0.7%. This seems to be related to the procedure, although firm conclusions cannot be drawn. LEVEL OF EVIDENCE: Level 2-prospective cohort.

Cervical sagittal alignment after different anterior discectomy procedures for single-level cervical degenerative disc disease: randomized controlled trial.

BACKGROUND: The effect of anterior cervical discectomy without fusion (ACD), ACD with fusion by stand-alone cage (ACDF) or with arthroplasty (ACDA) on cervical sagittal alignment is not known and is the subject of this study. METHODS: A total of 142 adult patients with single-level cervical disease were at random allocated to different procedures: ACD (45), ACDF (47) and ACDA (50). Upright cervical spine radiographs were obtained. Angles of the involved angle and the angle between C2 and C7 were determined. RESULTS: After a mean follow-up of 25.4 ± 18.4 months, the angles of the involved level comparing ACD with ACDA and ACD with ACDF were different, reaching statistical significance. However, the angle between C2 and C7 did not differ between groups or between preoperative values and at follow-up. CONCLUSIONS: Irrespective of the technique used for anterior cervical discectomy for single-level degenerative disc disease, the alignment of the cervical spine is unaltered.

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.

Reporting the results of meta-analyses: a plea for incorporating clinical relevance referring to an example.

BACKGROUND CONTEXT: The results of meta-analyses are frequently reported, but understanding and interpreting them is difficult for both clinicians and patients. Statistical significances are presented without referring to values that imply clinical relevance. PURPOSE: This study aimed to use the minimal clinically important difference (MCID) to rate the clinical relevance of a meta-analysis. STUDY DESIGN: This study is a review of the literature. PATIENT SAMPLE: This study is a review of meta-analyses relating to a specific topic, clinical results of cervical arthroplasty. OUTCOME MEASURE: The outcome measure used in the study was the MCID. METHODS: We performed an extensive literature search of a series of meta-analyses evaluating a similar subject as an example. We searched in Pubmed and Embase through August 9, 2016, and found articles concerning meta-analyses of the clinical outcome of cervical arthroplasty compared with that of anterior cervical discectomy with fusion in cases of cervical degenerative disease. We evaluated the analyses for statistical significance and their relation to MCID. MCID was defined based on results in similar patient groups and a similar disease entity reported in the literature. RESULTS: We identified 21 meta-analyses, only one of which referred to MCID. However, the researchers used an inappropriate measurement scale and, therefore, an incorrect MCID. The majority of the conclusions were based on statistical results without mentioning clinical relevance. CONCLUSIONS: The majority of the articles we reviewed drew conclusions based on statistical differences instead of clinical relevance. We recommend introducing the concept of MCID while reporting the results of a meta-analysis, as well as mentioning the explicit scale of the analyzed measurement.

An assessment of the most reliable method to estimate the sagittal alignment of the cervical spine: analysis of a prospective cohort of 138 cases.

OBJECTIVE Although there is increasing recognition of the importance of cervical spinal sagittal balance, there is a lack of consensus as to the optimal method to accurately assess the cervical sagittal alignment. Cervical alignment is important for surgical decision making. Sagittal balance of the cervical spine is generally assessed using one of two methods; namely, measuring the angle between C-2 and C-7, and drawing a line between C-2 and C-7. Here, the best method to assess sagittal alignment of the cervical spine is investigated. METHODS Data from 138 patients enrolled in a randomized controlled trial (Procon) were analyzed. Two investigators independently measured the angle between C-2 and C-7 by using Harrison's posterior tangent method, and also estimated the shape of the sagittal curve by using a modified Toyama method. The mean angles of each quantitative assessment of the sagittal alignment were calculated and the results were compared. The interrater reliability for both methods was estimated using Cronbach's alpha. RESULTS For both methods the interrater reliability was high: for the posterior tangent method it was 0.907 and for the modified Toyama technique it was 0.984. For a lordotic cervical spine, defined by the modified Toyama method, the mean angle (defined by Harrison's posterior tangent method) was 23.4° ± 9.9° (range 0.4°-52.4°), for a kyphotic cervical spine it was -2.2° ± 9.2° (range -16.1° to 16.9°), and for a straight cervical spine it was 10.5° ± 8.2° (range -11° to 36°). CONCLUSIONS An absolute measurement of the angle between C-2 and C-7 does not unequivocally define the sagittal cervical alignment. As can be seen from the minimum and maximum values, even a positive angle between C-2 and C-7 could be present in a kyphotic spine. For this purpose, the modified Toyama method (drawing a line from the posterior inferior part of the vertebral body of C-2 to the posterior upper part of the vertebral body of C-7 without any measurements) is a better tool for a global assessment of cervical sagittal alignment. Clinical trial registration no.: ISRCTN41681847 ( https://www.isrctn.com ).

Comparison of biomechanical properties of cervical artificial disc prosthesis: a review.

Cervical artificial discs are frequently implanted. Clinical data are frequently presented. However, biomechanical data are scarce. The literature is extensively reviewed following general rules for systemic review. The manufacturers of cervical artificial discs are requested for information. Only 10 articles were suitable for review. Together with some information of the manufacturer, data of 5 out of 8 discs can be provided. Comparison is not possible since testing methods differ. Before introduction of a new device biomechanical data should be provided. This should be done after standardized testing and presentation of the results. Only then comparison is possible as is a responsible choice for our patients.

Self-rated evaluation of outcome of the implantation of interspinous process distraction (X-Stop) for neurogenic claudication.

The treatment of lumbar spinal stenosis is either conservative or surgical decompression. Recently, an interspinous decompression device (X-Stop) has been developed as an alternative. Patients treated with an X-Stop between 2003 and 2006 are subject of this study. The SF-36 Health Survey and Zürich Questionnaires are used. The data of pre- and post-operative self-rated questionnaires are collected and analysed by independent investigators. The data were statistically analysed. A good outcome was defined when the mean score at the ZQ for satisfaction was at maximal 2.0, and the mean improvement of the severity score was at least 0.5, and also for vitality score. For relations between outcome and gender, smoking, BMI, orthopaedic co-morbidity, number of implanted X-Stops were sought. The change in SF-36 scales was related to the outcome. Sixty-five patients did undergo implantation of an X-Stop. The mean age was 64.4 +/- 10.0 years (range: 37.0-85.0 years). 31.1% Of the patients had a good outcome. A good outcome was not related to smoking, BMI, number of implanted X-Stops. However, a good outcome was related to the absence of orthopaedic co-morbidity or male gender. Patients with a good outcome had significantly a better improvement of the scales of the SF-36 concerning physical pain or impairment. The X-Stop does improve the clinical situation. However, a good outcome is achieved less often than previously reported. Probable explanations are discussed.

The trochlea is medialized by total knee arthroplasty: an intraoperative assessment in 61 patients.

BACKGROUND: A medialization of the femoral component in a total knee arthroplasty (TKA) causes abnormal patellar tracking, which could result in patellar instability, pain, wear, and failure. Previous reports defined medialization in relation to the neutral position of the femoral component, but omitted to compare it to the anatomical position of the trochlea. We assessed intraoperatively whether there is a systematic error of the position of the prosthetic groove relative to the anatomical trochlea. MATERIAL AND METHODS: A special instrument was developed to measure consecutively the mediolateral position of the anatomical trochlea and the mediolateral position of the prosthetic groove. 3 experienced knee surgeons determined the mediolateral error of the prosthetic groove in primary TKAs in 61 patients. RESULTS: There was a significant medial error of the prosthetic groove relative to the preoperative position of the trochlea, with a mean medial error of 2.5 mm (SD 3.3) INTERPRETATION: Our findings indicate that the trochlea is medialized by TKA. Because a conscious medialization of the femoral component in a TKA produces abnormal patellar tracking patterns, further investigations will be needed to analyze the clinical consequences of this medialization of the trochlea.

Subsidence of stand-alone cervical carbon fiber cages.

OBJECTIVE: To investigate the number of subsidences of inserted cervical carbon fiber cages and to define predictive factors for subsidence. METHODS: All patients treated for a cervical herniated disc and fusion with a cervical carbon fiber cage between January 2002 and December 2003 were retrospectively identified. The radiological examinations were reviewed, and, especially, the presence of subsidence was noted. Possible predictive factors for subsidence were determined before the investigation. RESULTS: In 69 patients, there were 96 cages inserted, of which 29.2% subsided. Of all factors investigated, only smoking seemed to be predictive for subsidence, whereas insertion at C6 to C7 clearly had a higher risk at subsidence. Subsidence was not related to outcome or fusion. CONCLUSION: Although the high number of subsidence of cages has never been described before, clinical outcome and fusion rate is comparable with the literature.