Paul C Willems

Maastricht Universitair Medisch Centrum, Maestricht, Limburg, Netherlands

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Publications (33)99.5 Total impact

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    ABSTRACT: Background and purpose — Outcome measurement has been shown to improve performance in several fields of healthcare. This understanding has driven a growing interest in value-based healthcare, where value is defined as outcomes achieved per money spent. While low back pain (LBP) constitutes an enormous burden of disease, no universal set of metrics has yet been accepted to measure and compare outcomes. Here, we aim to define such a set. Patients and methods — An international group of 22 specialists in several disciplines of spine care was assembled to review literature and select LBP outcome metrics through a 6-round modified Delphi process. The scope of the outcome set was degenerative lumbar conditions. Results — Patient-reported metrics include numerical pain scales, lumbar-related function using the Oswestry disability index, health-related quality of life using the EQ-5D-3L questionnaire, and questions assessing work status and analgesic use. Specific common and serious complications are included. Recommended follow-up intervals include 6, 12, and 24 months after initiating treatment, with optional follow-up at 3 months and 5 years. Metrics for risk stratification are selected based on pre-existing tools. Interpretation — The outcome measures recommended here are structured around specific etiologies of LBP, span a patient’s entire cycle of care, and allow for risk adjustment. Thus, when implemented, this set can be expected to facilitate meaningful comparisons and ultimately provide a continuous feedback loop, enabling ongoing improvements in quality of care. Much work lies ahead in implementation, revision, and validation of this set, but it is an essential first step toward establishing a community of LBP providers focused on maximizing the value of the care we deliver.
    Acta Orthopaedica 03/2015; DOI:10.3109/17453674.2015.1036696 · 2.45 Impact Factor
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    ABSTRACT: Study DesignProspective clinical study of intradiscal methylene blue injection for the treatment of lumbar discogenic pain.Objective The objective of this study was to collect information about efficacy, safety, and acceptability of the intervention, gain and burden of outcome measures, and sample size assumptions for a potential following randomized controlled trial (RCT). If the pilot study demonstrates that this treatment is potentially effective and safe, and the methods and procedures used in this study are feasible, a RCT follows.Summary of Background DataLow back pain (LBP) is a highly common problem with a lifetime prevalence of more than 70%. A substantial part of chronic LBP is attributable to degenerative changes in the intervertebral disc. A recently published RCT assessing the treatment intradiscal injection of methylene blue for chronic discogenic LBP, showed exceptionally good results.Methods Patients were selected on clinical criteria, magnetic resonance imaging, and a positive provocative discogram. The primary outcome measure was mean pain reduction at 6 months.ResultsFifteen consecutive patients with chronic lumbar discogenic pain enrolled in a multicenter prospective case series in two interventional pain treatment centers in the Netherlands. Six months after the intervention, 40% of the patients claimed at least 30% pain relief. In patients who responded, physical function improved and medication use diminished. We observed no procedural complications or adverse events. Predictors for success were Pfirrmann grading of 2 or less and higher quality of life mental component scores.Conclusions Our findings of 40% positive respondents, and no complications, give reason to set up a randomized, double-blind, placebo-controlled, trial.
    Pain Practice 02/2015; DOI:10.1111/papr.12283 · 2.18 Impact Factor
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    ABSTRACT: Fracture healing is an active process with early changes in bone and inflammation. We performed an exploratory study evaluating the association between early changes in densitometric, structural, biomechanical and biochemical bone parameters during the first weeks of fracture healing and wrist-specific pain and disability at 12 weeks in postmenopausal women with a conservatively treated distal radius fracture.Eighteen patients (68 ± 8 years) were evaluated at 1-2, and 3-4 weeks post-fracture, using high-resolution peripheral quantitative computed tomography (HR-pQCT), micro-finite element analysis, serum procollagen type-I N-terminal propeptide (P1NP), carboxy-terminal telopeptide of type I collagen (ICTP) and high-sensitive C-reactive protein (hsCRP). After 12 weeks, patients rated their pain and disability using Patient Rated Wrist Evaluation (PRWE) questionnaires. Additionally, Quick Disability of the Arm Shoulder and Hand (QuickDASH) questionnaire and active wrist range of motion was evaluated. Linear regression models were used to study the relationship between changes in bone parameters and in hsCRP from visit 1 to 2 with PRWE score after 12 weeks.A lower PRWE outcome, indicating better outcome, was significantly related to an early increase in trabecular BMD [β:-0.96 (95%CI: -1.75 to -0.16), R2 = 0.37], in torsional stiffness [-0.14 (-0.28 to -0.004); R2 = 0.31], and to an early decrease in trabecular separation [209 (15 to 402), R2 = 0.33] and in ICTP [12.1 (0.0 to 24.1); R2 = 0.34]. Similar results were found for QuickDASH. Higher total dorsal and palmar flexion range of motion was significantly related to early increase in hsCRP [9.62 (3.90 to 15.34), R2 = 0.52].This exploratory study indicates that the assessment of early changes in trabecular BMD, trabecular separation, calculated torsional stiffness, bone resorption marker ICTP and hsCRP after a distal radius fracture provides valuable information regarding the 12 week clinical outcome in terms of pain, disability and range of motion and validates its use in studies on the process of early fracture healing. © 2014 American Society for Bone and Mineral Research
    Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 09/2014; 29(9). DOI:10.1002/jbmr.2225 · 6.59 Impact Factor
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    ABSTRACT: In clinical practice, fracture healing is evaluated by clinical judgment in combination with conventional radiography. Due to limited resolution, radiographs don’t provide detailed information regarding the bone micro-architecture and bone strength. Recently, assessment of in vivo bone density, architectural and mechanical properties at the micro-scale became possible using high resolution peripheral quantitative computed tomography (HR-pQCT) in combination with micro finite element analysis (μFEA). So far, such techniques have been used mainly to study intact bone. The aim of this study was to explore whether these techniques can also be used to assess changes in bone density, micro-architecture and bone stiffness during fracture healing. Therefore, the fracture region in eighteen women, aged 50 years or older with a stable distal radius fracture, was scanned using HR-pQCT at 1-2 (baseline), 3-4, 6-8 and 12 weeks post-fracture. At 1-2 and 12 weeks post-fracture the distal radius at the contra-lateral side was also scanned as control. Standard bone density, micro-architectural and geometric parameters were calculated and bone stiffness in compression, torsion and bending was assessed using μFEA. A linear mixed-effect model with time post-fracture as fixed effect was used to detect significant (p-value ≤ 0.05) changes from baseline. Wrist pain and function was scored using the patient-rated wrist evaluation (PRWE) questionnaire. Correlations between the bone parameters and the PRWE score was calculated by Spearman’s correlation coefficient. At the fracture site, total and trabecular bone density increased by 11% and 20%, respectively, at 6-8 weeks, whereas cortical density was decreased by 4%. Trabecular thickness increased by 23-31% at 6-8 and 12 weeks and the intertrabecular area became blurred, indicating intertrabecular bone formation. Compared to baseline, calculated bone stiffness in compression, torsion and bending were increased by 31% after 12 weeks. A moderate negative correlation was found between the stiffness and the PRWE score. No changes were observed at the contra-lateral side. The results demonstrate that it is feasible to assess clinically relevant and significant longitudinal changes in bone density, micro-architecture and mechanical properties at the fracture region during the healing process of stable distal radius fractures using HR-pQCT.
    Bone 07/2014; 64. DOI:10.1016/j.bone.2014.03.043 · 4.46 Impact Factor
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    ABSTRACT: A fracture liaison service model of care is widely recommended and applied, but data on its effectiveness are scarce. Therefore, the risk of subsequent nonvertebral fractures and mortality within two years after a nonvertebral fracture was analyzed in patients who presented to a hospital with a fracture liaison service and a hospital without a fracture liaison service. In 2005 to 2006, all consecutive patients with an age of fifty years or older presenting with a nonvertebral fracture were included. In the group that presented to a hospital without a fracture liaison service (the no-FLS group), only standard fracture care procedures were followed to address proper fracture-healing. In the group that presented to a hospital with a fracture liaison service (the FLS group), dual x-ray absorptiometry scans and laboratory testing were performed, and if applicable, patients were treated according to the Dutch guideline for osteoporosis. The risk for subsequent nonvertebral fracture and mortality were analyzed using multivariable Cox regression models with adjustments for age, sex, and baseline fracture location. In total, 1412 patients presented to the fracture liaison service (73.2% were women, and the mean age was 71.1 years), and 1910 underwent standard fracture care (69.8% were women, and the mean age was 69.5 years). After adjustment for age, sex, and baseline fracture location, patients who attended the fracture liaison service had a significantly lower mortality risk (hazard ratio: 0.65; 95% confidence interval [CI]: 0.53 to 0.79) over two years of follow-up. The subsequent nonvertebral fracture risk was also significantly lower in the patients in the FLS group, but this effect was time-dependent, with a hazard ratio of 0.84 (95% CI: 0.64 to 1.10) at twelve months and 0.44 (95% CI: 0.25 to 0.79) at twenty-four months. Patients seen at the fracture liaison service had a significantly lower mortality and subsequently a lower risk of nonvertebral fracture than those not seen at the fracture liaison service, with a reduction of 35% and 56%, respectively, over two years of follow-up. A fracture liaison service appears to be a successful approach to reduce the number of subsequent fractures and premature mortality in this cohort of patients. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
    The Journal of Bone and Joint Surgery 02/2014; 96(4):e29. DOI:10.2106/JBJS.L.00223 · 4.31 Impact Factor
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    ABSTRACT: an animal study. To explore ultra high molecular weight polyethylene (UHMWPE) sublaminar wires in spinal surgery and to assess stability and biocompatibility of the UHMWPE instrumentation in an ovine model. Sublaminar wiring is a well established technique in segmental scoliosis surgery. However, during introduction and/or removal of the metal sublaminar wires neurologic problems can occur. Abrasion after cutting metal wires for removal can lead to damage to the dural sac. Sublaminar wires have to withhold large forces and breakage of the wires can occur. Different types of sublaminar wires have been developed to address these problems. UHMWPE sublaminar wires can potentially substitute currently used metal sublaminar metal wires. In vivo testing and biocompatibility analysis of UHMWPE wires are recommended before clinical use in spinal surgery. In 6 immature sheep, pedicle screws were instrumented at lumbar level L4 and attached with titanium rods to four thoracolumbar vertebrae using 3 mm and 5 mm wide UHMWPE sublaminar wiring constructions in 5 animals. Titanium sublaminar wires were applied in one animal to function as a control subject. After a follow-up period of 16 weeks, the animals were sacrificed and the spines were isolated. Radiographs and CT-scans were made to assess stability of the instrumentation. The vertebrae were dissected for macroscopic and histological evaluation. None of the wires had loosened and the instrumentation remained stable. CT-scans and radiographs showed no signs of failure of the instrumentation and no neurological complications occurred. Although several bony bridges were seen on CT, growth was observed at the operated levels. Biocompatibility was assessed by macroscopical and histological analysis, showing no signs of dural or epidural inflammation. This pilot animal study shows that UHMWPE sublaminar wiring is a safe technique. The UHMWPE wires are biocompatible and provide sufficient stability in spinal instrumentation. Heterotopic ossification due to periost reactions in the ovine spine led to some restrictions in this study.
    Journal of spinal disorders & techniques 01/2014; DOI:10.1097/BSD.0b013e318291f580 · 1.89 Impact Factor
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    Paul Paul C. Willems
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    ABSTRACT: There is still no clear definition of diskogenic low-back pain and no consensus on a generally agreed test, such as provocative diskography (PD), to diagnose painful disk degeneration, and probably more importantly, to predict the outcome of therapy intended to reduce pain that is presumed to be diskogenic in nature. Nevertheless, PD is the most specific procedure to diagnose diskogenic low-back pain. Its accuracy, however, is rather low or at best unknown. Although rare, the most prevalent complication, postdiskography diskitis, can be devastating for the individual patient, so all measures, like strict sterile conditions and antibiotic prophylaxis, should be taken to avoid this complication. It is advised to perform the procedure in a pressure-controlled way with a constant low flow, and optionally computed tomography imaging. PD should not be performed in morphologically normal disks. A standardized execution of the test should be established in order to perform high-quality studies to determine its accuracy to lead to meaningful interventions, and find best practices for diagnosis and treatment of diskogenic back pain. Possibly, PD may have detrimental effects on the disk, causing early degeneration, although it is unknown whether this will be related to clinical symptoms. Especially with these possible adverse side effects in mind, the risk-benefit ratio with the lack of clear benefits from treatments provided, and possible complications of disk puncture, the rationale for PD is questionable, which should be stressed to patients in the process of shared decision making. Diskography as a stand-alone test is not recommended in clinical decision making for patients with chronic low-back pain.
    Journal of Pain Research 01/2014; 7:699-705. DOI:10.2147/JPR.S45615
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    European Spine Journal 09/2013; 23(2). DOI:10.1007/s00586-013-3000-5 · 2.47 Impact Factor
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    ABSTRACT: Purpose: Standard thoracotomy for anterior instrumentation and fusion of the thoracic spine in idiopathic scoliosis may have detrimental effects on pulmonary function. In this study we describe a less invasive anterior surgical technique and show the pre- and postoperative pulmonary function with a minimum follow-up of 2 years. Twenty patients with Lenke type 1 adolescent thoracic idiopathic scoliosis were treated with anterior spinal fusion and instrumentation. The mean preoperative Cobb angle of the thoracic curve was 53[degree sign] +/- 5.8. Pulmonary function tests (PFT) and radiographic evaluation was performed. The mean postoperative correction in Cobb angle of the thoracic curve was 27[degree sign] +/- 8.2 (49%).The mean preoperative FEV1 was 2.81 +/- 0.43 L, which increased to 3.14 +/- 0.50 L at 2 years postoperatively (P = 0.000). The mean FEV1% did not change (89.60 +/- 7.49% preoperatively, versus 90.53 +/- 5.95% at 2 years follow-up, P = 0.467). The TLC increased from 4.62 +/- 0.62 L preoperatively to 5.17 +/- 0.63 L at 2 years follow-up (P = 0.000). The FEV1% at two years of follow-up improved to 104% of the FEV1% predicted value. The FEV1 improved to 97% of the FEV1 predicted value. Anterior spinal fusion for idiopathic scoliosis by means of a minimal open thoracotomy proved to be a safe surgical technique that resulted in an improvement of pulmonary function. Our results are similar to those of thoracoscopic procedures reported in literature.
    Scoliosis 08/2013; 8(1):14. DOI:10.1186/1748-7161-8-14 · 1.31 Impact Factor
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    ABSTRACT: PURPOSE: A possible complication after total disc replacement (TDR) is subsidence, presumably caused by asymmetric implantation, implant undersizing or reduced bone quality. This study aims to quantify the degree of subsidence of an SB Charité TDR, and investigate whether undersizing is related to subsidence. METHODS: A custom developed software package (Mathworks) reconstructed 3D bone-implant geometry. A threshold for subsidence was determined by comparing penetrated bone volume (PBV) and rotation angles. Inter- and intra-observer reproducibilities were calculated. Subsidence was correlated to undersizing. RESULTS: High inter- and intra-observer correlation coefficients were found for the method (R > 0.92). Subsidence was quantified as PBV 700 mm(3) combined with a rotation angle >7.5°. A reduced risk of subsidence was correlated to >60 and >62 % of the bony endplate covered by the TDR endplate for L4 and L5, respectively. CONCLUSIONS: A reproducible method to determine undersizing was developed. Thresholds were determined related to a reduced risk of subsidence.
    European Spine Journal 06/2013; 22(10). DOI:10.1007/s00586-013-2864-8 · 2.47 Impact Factor
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    ABSTRACT: PURPOSE: Many systematic reviews have been published on surgical interventions for low back disorders. The objective of this overview was to evaluate the available evidence from systematic reviews on the effectiveness of surgical interventions for disc herniation, spondylolisthesis, stenosis, and degenerative disc disease (DDD). An earlier version of this review was published in 2006 and since then, many new, better quality reviews have been published. METHODS: A comprehensive search was performed in the Cochrane database of systematic reviews (CDSR), database of reviews of effectiveness (DARE) and Pubmed. Two reviewers independently performed the selection of studies, risk of bias assessment, and data extraction. Included are Cochrane reviews and non-Cochrane systematic reviews published in peer-reviewed journals. The following conditions were included: disc herniation, spondylolisthesis, and DDD with or without spinal stenosis. The following comparisons were evaluated: (1) surgery vs. conservative care, and (2) different surgical techniques compared to one another. The methodological quality of the systematic reviews was evaluated using AMSTAR. We report (pooled) analyses from the individual reviews. RESULTS: Thirteen systematic reviews on surgical interventions for low back disorders were included for disc herniation (n = 6), spondylolisthesis (n = 2), spinal stenosis (n = 4), and DDD (n = 4). Nine (69 %) were of high quality. Five reviews provided a meta-analysis of which two showed a significant difference. For the treatment of spinal stenosis, intervertebral process devices showed more favorable results compared to conservative treatment on the Zurich Claudication Questionnaire [mean difference (MD) 23.2 95 % CI 18.5-27.8]. For degenerative spondylolisthesis, fusion showed more favorable results compared to decompression for a mixed aggregation of clinical outcome measures (RR 1.40 95 % CI 1.04-1.89) and fusion rate favored instrumented fusion over non-instrumented fusion (RR 1.37 95 % CI 1.07-1.75). CONCLUSIONS: For most of the comparisons, the included reviews were not significant and/or clinically relevant differences between interventions were identified. Although the quality of the reviews was quite acceptable, the quality of the included studies was poor. Future studies are likely to influence our assessment of these interventions.
    European Spine Journal 05/2013; 22(9). DOI:10.1007/s00586-013-2823-4 · 2.47 Impact Factor
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    ABSTRACT: Background We analysed whether a combination of bone- and fall-related risk factors (RFs) in addition to a recent non-vertebral fracture (NVF) contributed to subsequent NVF risk and mortality during 2-years in patients who were offered fall and fracture prevention according to Dutch fracture- and fall-prevention guidelines. Methods 834 consecutive patients aged ≥50 years with a recent NVF who were included. We compared subgroups of patients according to the presence of bone RFs and/or fall RFs (group 1: only bone RFs; group 2: combination of bone and fall RFs; group 3: only fall RFs; group 4: no additional RFs). Univariable and multivariable Cox regression analyses were performed adjusted for age, sex and baseline fracture location (major or minor). Results 57 (6.8%) had a subsequent NVF and 29 (3.5%) died within 2-years. Univariable Cox regression analysis showed that patients with the combination of bone and fall RFs had a 99% higher risk in subsequent fracture risk compared to all others (Hazard Ratio (HR) 1.99; 95% Confidence Interval (CI) 1.18-3.36) Multivariable analyses this was borderline not significant (HR 1.70; 95% CI: 0.99-2.93). No significant differences in mortality were found between the groups. Conclusion Evaluation of fall RFs contributes to identifying patients with bone RFs at highest immediate risk of subsequent NVF in spite of guideline-based treatment. It should be further studied whether earlier and immediate prevention following a NVF can decrease fracture risk in patients with a combination of bone and fall RFs.
    BMC Musculoskeletal Disorders 04/2013; 14(1):121. DOI:10.1186/1471-2474-14-121 · 1.90 Impact Factor
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    Paul Willems
    Acta orthopaedica. Supplementum 02/2013; 84(349):1-37. DOI:10.3109/17453674.2012.753565
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    ABSTRACT: BACKGROUND CONTEXT: Spinal fusion is a common but controversial treatment for chronic low back pain (LBP) with outcomes similar to those of programmed conservative care. To improve the results of fusion, tests for patient selection are used in clinical practice. PURPOSE: To determine the prognostic accuracy of tests for patient selection that are currently used in clinical practice to identify those patients with chronic LBP who will benefit from spinal fusion. STUDY DESIGN: Systematic review of the literature. SAMPLE: Studies that compared the results of magnetic resonance imaging (MRI), provocative discography, facet joint blocks, orthosis immobilization, and temporary external fixation with the clinical outcome of patients who underwent spinal fusion for chronic LBP. OUTCOME MEASURES: To determine the prognostic accuracy of tests to predict the clinical outcome of spinal fusion in terms of sensitivity, specificity, and likelihood ratios (LRs). METHODS: Data sources PubMed (1966 to November 2010), EMBASE (1974 to November 2010), and reference lists were searched without restriction by language or publication status. Two reviewers independently selected studies for inclusion, extracted data for analysis, and assessed the risk of bias with the Quality Assessment of Diagnostic Accuracy Studies checklist, modified for prognostic studies. Discrepancies were resolved by consensus. RESULTS: Ten studies met the eligibility criteria. Immobilization by an orthosis (median [range] positive LR, 1.10 [0.94-1.13] and negative LR, 0.92 [0.39-1.12]), provocative discography (median [range] positive LR, 1.18 [0.70-1.71] and negative LR, 0.74 [0.24-1.40]), and temporary external fixation (median [range] positive LR, 1.22 [1.02-1.74] and negative LR, 0.58 [0.15-0.94]) failed to show clinically useful prognostic accuracy. Statistical pooling was not feasible because of different test protocols, variability in outcome assessment, and heterogeneous patient populations. No studies reporting on facet joint blocks or MRI could satisfy the inclusion criteria. Obscure patient selection, high risk of verification bias, and outcome assessment with poorly validated instruments precluded strong conclusions for all tests. CONCLUSIONS: No subset of patients with chronic LBP could be identified for whom spinal fusion is a predictable and effective treatment. Best evidence does not support the use of current tests for patient selection in clinical practice.
    The spine journal: official journal of the North American Spine Society 11/2012; 13(2). DOI:10.1016/j.spinee.2012.10.001 · 2.80 Impact Factor
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    ABSTRACT: Posterior lumbar interbody fusion (PLIF) is a method that allows decompression of the spinal canal and nerve roots by laminectomy combined with fusion by means of intervertebral cages filled with bone graft and pedicle screw fixation. Conventional imaging techniques, such as plain radiography and computed tomography (CT), have limitations to assess bony fusion dynamics. In 16 PLIFs of 15 patients with persisting symptoms, positron-emission tomography (PET)/CT scans were made 60 min after intravenous administration of 156 to 263 MBq of 18 F-fluoride, including 1-mm sliced, high-dose, non-contrast-enhanced CT scanning. Maximal standard uptake values (SUVmax) of various regions were calculated and correlated with abnormalities on CT. Subsidence of the cages into the vertebral endplates was the most frequently observed abnormality on CT (in 16 of 27 or 59% of evaluable endplates). Endplate SUVmax values were significantly higher for those patients with pronounced (p < 0.0001) or moderate (p < 0.013) subsidence as compared to those with no subsidence. Additionally, a significant correlation between vertebral and ipsilateral pedicle screw entrance SUVmax values (p < 0.009) was found, possibly indicating posterior transmission of increased bone stress. In our patient group, intercorporal fusion was seen on CT in 63% but showed no correlation to intercorporal SUVmax values. With the use of 18 F-fluoride PET/CT, intervertebral cage subsidence appeared to be a prominent finding in this patient group with persisting symptoms, and highly correlating with the degree of PET hyperactivity at the vertebral endplates and pedicle screw entry points. Further study using 18 F-fluoride PET/CT should specifically assess the role of metabolically active subsidence in a prospective patient group, to address its role in nonunion and as a cause of persisting pain.
    07/2012; 2(1):42. DOI:10.1186/2191-219X-2-42
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    ABSTRACT: Purpose To compare mid-term clinical outcomes of two revision strategies for patients with failed SB Charité III total disc replacements (TDRs). Methods Eighteen patients with a failed TDR underwent posterolateral instrumented fusion (fusion group); in 21 patients, the TDR was removed and the intervertebral defect was filled with a bone strut graft, followed by an instrumented posterolateral fusion (removal group). Visual analogue scale (VAS) for pain and Oswestry Disability Index (ODI) were completed pre- and post-revision surgery. Intra- and post-operative complications of both revision strategies were assessed. Results Mean follow-up was 3.7 years (range 1.0–6.4) in the removal group and 4.4 years (range 0.7–11.0) in the fusion group. Although the removal group showed a significantly lower VAS and ODI score post-revision surgery as compared to preoperative (P < 0.01 and P = 0.01, respectively), no significant differences were found between the removal and fusion groups before and after revision surgery in VAS and ODI. A clinical relevant improvement in VAS and ODI was found in 47 and 21 % respectively in the removal group, and in 22 and 27 % respectively in the fusion group. Substantial complications were observed only in the removal group. Conclusions Both procedures showed improvement clinically. There were no significant additional benefits of removing the TDR as compared to fusion alone at mid-term follow-up. The clinical decision to remove the TDR should be carefully weighed up against potential risks and complications of this procedure.
    European Spine Journal 05/2012; 21(12). DOI:10.1007/s00586-012-2354-4 · 2.47 Impact Factor
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    ABSTRACT: This study evaluates the short-term clinical outcome, radiological, histological and device retrieval findings of two patients with second generation lumbar total disc replacement (TDR). The first patient had a single level L4-L5 Activ-L TDR, the second patient a L4-L5 Mobidisc and L5-S1 Activ-L TDR. The TDRs were implanted elsewhere and had implantation times between 1.3 and 2.8 years. Plain radiographs and CT-scanning showed slight subsidence of the Activ-L TDR in both patients and facet joint degeneration. The patients underwent revision surgery because of recurrent back and leg pain. After removal of the TDR and posterolateral fusion, the pain improved. Histological examination revealed large ultrahigh molecular weight polyethylene (UHMWPE) particles and giant cells in the retrieved tissue surrounding the Mobidisc. The particles in the tissue samples of the Activ-L TDR were smaller and contained in macrophages. Retrieval analysis of the UHMWPE cores revealed evidence of minor adhesive and abrasive wear with signs of impingement in both TDR designs. Although wear was unrelated to the reason for revision, this study demonstrates the presence of UHMWPE particles and inflammatory cells in second generation TDR. Long-term follow-up after TDR is indicated for monitoring wear and implant status.
    European Spine Journal 01/2012; 21 Suppl 4:S513-20. DOI:10.1007/s00586-011-2141-7 · 2.47 Impact Factor
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    ABSTRACT: Study Design. A systematic review of randomized controlled trials (RCTs). Objective. To assess the effects of arthroplasty versus fusion in the treatment of radiculopathy or myelopathy, or both, due to single-level cervical degenerative disc disease. Summary of Background Data. There is ongoing debate about whether fusion or arthroplasty is superior in the treatment of single-level cervical degenerative disc disease. Mainly because the intended advantage of arthroplasty compared with fusion, prevention of symptoms due to adjacent segment degeneration in the long term, is not confirmed yet. Until sufficient long-term results become available, it is important to know whether results of 1 of the 2 treatments are superior to the other in the first 1 to 2 years. Methods. We searched electronic databases for randomized controlled trials. We included randomized controlled trials that directly compared any type of cervical fusion with any type of cervical arthroplasty, with at least 1 year of follow-up. Study selection was performed independently by 3 review authors, and "risk of bias" assessment and data extraction were independently performed by 2 review authors. In case of missing data, we contacted the study authors or the study sponsor. We assessed the quality of evidence. Results. Nine studies (2400 participants) were included in this review; 5 of these studies had a low risk of bias. Results for the arthroplasty group were better than the fusion group for all primary comparisons, often statistically significant. For none of the primary outcomes was a clinically relevant difference in effect size shown. Quality of the evidence was low to moderate. Conclusion. There is low to moderate quality evidence that results are consistently in favor of arthroplasty, often statistically significant. However, differences in effect size were invariably small and not clinically relevant for all primary outcomes.
    Cochrane database of systematic reviews (Online) 01/2012; 9(17):CD009173. DOI:10.1002/14651858.CD009173.pub2 · 5.94 Impact Factor
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    ABSTRACT: Objectives To assess the use of prognostic patient factors and predictive tests in clinical decision making for spinal fusion in patients with chronic low back pain. Design and setting Nationwide survey among spine surgeons in the Netherlands. Participants Surgeon members of the Dutch Spine Society were questioned on their surgical treatment strategy for chronic low back pain. Primary and secondary outcome measures The surgeons' opinion on the use of prognostic patient factors and predictive tests for patient selection were addressed on Likert scales, and the degree of uniformity was assessed. In addition, the influence of surgeon-specific factors, such as clinical experience and training, on decision making was determined. Results The comments from 62 surgeons (70% response rate) were analysed. Forty-four surgeons (71%) had extensive clinical experience. There was a statistically significant lack of uniformity of opinion in seven of the 11 items on prognostic factors and eight of the 11 items on predictive tests, respectively. Imaging was valued much higher than predictive tests, psychological screening or patient preferences (all p<0.01). Apart from the use of discography and long multisegment fusions, differences in training or clinical experience did not appear to be of significant influence on treatment strategy. Conclusions The present survey showed a lack of consensus among spine surgeons on the appreciation and use of predictive tests. Prognostic patient factors were not consistently incorporated in their treatment strategy either. Clinical decision making for spinal fusion to treat chronic low back pain does not have a uniform evidence base in practice. Future research should focus on identifying subgroups of patients for whom spinal fusion is an effective treatment, as only a reliable prediction of surgical outcome, combined with the implementation of individual patient factors, may enable the instalment of consensus guidelines for surgical decision making in patients with chronic low back pain.
    BMJ Open 12/2011; 1(2):e000391. DOI:10.1136/bmjopen-2011-000391 · 2.06 Impact Factor
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    ABSTRACT: Systematic implementation of guidelines in patients presenting with a fracture increases identification of patients at high risk for subsequent fractures and contributes to a decreased fracture risk. Its effect on prevention of subsequent fractures and on mortality has not been documented. The aim of this study was to determine the impact of the implementation of specific guidelines on the risk of subsequent fractures and mortality in patients presenting with a non-vertebral fracture (NVF). Before-after impact analysis in consecutive patients older than 50 years who were admitted to the hospital with a NVF during 2 periods: pre-intervention group (n = 1,920, enrolled in 1999-2001) and intervention group (n = 1,335, enrolled in 2004-2006). The intervention consisted of a dedicated fracture nurse who systematically offered fracture risk evaluation and treatment according to available guidelines. The 2-year absolute risk (AR) and hazard ratio's (HR, with 95% confidence interval (CI)) of subsequent NVFs and mortality were analysed between both groups after adjustment for age, sex and baseline fracture location by multivariable Cox regression and by intention-to-treat. The AR of subsequent fracture was 9.9% before and 6.7% after intervention, indicating a decrease of 35% in the risk of subsequent fracture (HR 0.65; CI: 0.51-0.84, after adjustment for age, sex and baseline fracture location) and 17.9% and 11.6%, respectively, for subsequent mortality, indicating a decrease of 33% in the risk of subsequent mortality (HR: 0.67; CI: 0.55-0.81, after adjustment for age, sex and baseline fracture location). Systematic implementation of guidelines for fracture prevention by a dedicated fracture nurse immediately after a NVF is associated with a significant reduction of the 2-year risk of subsequent NVF and mortality.
    Injury 09/2011; 42 Suppl 4:S39-43. DOI:10.1016/S0020-1383(11)70011-0 · 2.46 Impact Factor

Publication Stats

267 Citations
99.50 Total Impact Points

Institutions

  • 2009–2015
    • Maastricht Universitair Medisch Centrum
      • Central Diagnostic Laboratory
      Maestricht, Limburg, Netherlands
  • 2011–2014
    • Maastricht University
      • Department of Orthopaedic Surgery
      Maestricht, Limburg, Netherlands