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Dive into the research topics where Maarten C. de Waal Malefijt is active.

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Featured researches published by Maarten C. de Waal Malefijt.


Arthritis & Rheumatism | 2001

Change in bone mineral density in patients with rheumatoid arthritis during the first decade of the disease

Eric-Jan J. A. Kroot; Mieke G. Nieuwenhuizen; Maarten C. de Waal Malefijt; Piet L. C. M. van Riel; Pieternel C. M. Pasker-De Jong; R.F.J.M. Laan

OBJECTIVE Rheumatoid arthritis (RA) has been reported to be associated with bone loss during the first years of the disease. The magnitude of this problem after the initial years has not yet been evaluated. In the present study, the change in bone mineral density (BMD) in patients with recent-onset RA as well as the effects of inflammation, mobility, and the use of prednisone on this change were studied in the first decade of the disease. METHODS BMD was measured twice in 76 RA patients with mean disease durations of 2.35 years at the first BMD measurement and 8.90 years at the second BMD measurement. BMD was measured in both hips using dual x-ray absorptiometry. Results were expressed as mean +/- SEM Z scores (using age- and sex-matched reference values) and as mean +/- SEM percent change in BMD (in gm/cm2) per year. The effects of inflammation, mobility, and the use of prednisone on change in BMD were evaluated using multiple linear regression analyses. RESULTS At the first BMD measurement, RA patients had lower BMD compared with the reference values (Z score -0.42+/-0.11, 95% confidence interval [95% CI] -0.64, -0.20). Between the 2 measurements, we observed a small decrease in BMD of -0.28+/-0.11%/year (95% CI -0.07 to -0.49). However, the rate of bone loss was smaller than expected. The Z score increased by 0.13+/-0.05 between the 2 BMD measurements (95% CI 0.02, 0.23). Only the use of prednisone was significantly associated with increased bone loss. In a separate analysis that included only postmenopausal women, increased physical activity and longer time since menopause were both associated with decreased bone loss. In this subgroup of patients, the use of prednisone was significantly associated with increased bone loss as well. A high erythrocyte sedimentation rate was associated with increased bone loss, but this did not reach statistical significance. CONCLUSION After the initial years of the disease, bone loss in RA patients is lower than expected compared with age- and sex-matched reference values. Postmenopausal RA patients with low levels of physical activity are at increased risk of losing bone. Use of prednisone was the only variable consistently associated with reduction in BMD in RA patients.


Foot & Ankle International | 2008

Equivalent Correction in Scarf and Chevron Osteotomy in Moderate and Severe Hallux Valgus: A Randomized Controlled Trial:

Axel Deenik; Henk van Mameren; Enrico de Visser; Maarten C. de Waal Malefijt; Frits F Draijer; Rob A. de Bie

Background: Chevron osteotomy is a widely accepted osteotomy for correction of hallux valgus. 18 Algorithms were developed to overcome the limitations of distal osteotomies. Scarf osteotomy has become popular as a versatile procedure that should be able to correct most cases of acquired hallux valgus. The purpose of this study was to evaluate whether patients with moderate or severe hallux valgus have better correction with a scarf osteotomy as compared to chevron osteotomy. Materials and Methods: After informed consent, 136 feet in 115 patients were randomized to 66 scarf and 70 chevron osteotomies. Deformities of patients were classified as mild, moderate and severe according to IMA, and both groups were compared with independent t-tests. The results were measured using radiographic HVA, IMA and DMAA measurements. Results: There were no statistical differences in HVA, IMA and DMAA between scarf and chevron osteotomy in mild to moderate hallux valgus. In severe hallux valgus, chevron osteotomy corrected HVA better than scarf osteotomy, although this group consisted of twelve patients only. Five patients in the chevron group and seven in the scarf group developed recurrent subluxation of the metatarsophalangeal joint. Conclusion: In patients with moderate and severe hallux valgus, the results of chevron osteotomy were at least as effective as a scarf osteotomy. Recurrent subluxation of the first metatatarsophalangeal joint was the main cause for insufficient correction. We favor the chevron osteotomy because it is less invasive, without sacrificing correction of HVA and IMA.


Journal of Bone and Joint Surgery, American Volume | 2009

Acetabular Revision with Impacted Morselized Cancellous Bone Graft and a Cemented Cup in Patients with Rheumatoid Arthritis A Concise Follow-up, at Eight to Nineteen Years, of a Previous Report*

B. Willem Schreurs; Jaap S. Luttjeboer; Truike M. Thien; Maarten C. de Waal Malefijt; P. Buma; R.P.H. Veth; T.J.J.H. Slooff

Background: Acetabular revision in patients with rheumatoid arthritis is often difficult because of the poor quality and quantity of the acetabular bone stock. The purpose of this study was to evaluate the midterm clinical and radiographic outcomes of acetabular revision with use of an impaction bone-grafting technique and a cemented polyethylene cup.Methods: Thirty-five consecutive acetabular revisions were performed with impaction bone-grafting and use of a cemented cup in twenty-eight patients with rheumatoid arthritis. The average age at the revision was fifty-seven years. The minimum duration of follow-up of all reconstructions that were still functioning or that were followed until the time of death was three years (mean, 7.5 years; range, three to fourteen years). No patient was lost to follow-up, but five patients (six hips) died before the time of the review. The acetabular bone defects were classified as cavitary in twelve hips and as combined segmental-cavitary in twenty-three.Results: The five patients (six hips) who died had been doing well at the time of their latest follow-up. Of the remaining patients, six (six hips) had a repeat revision. The average Harris hip score of the living patients with a surviving implant at the time of follow-up was 82 points, and there was no or only mild pain in twenty-one of the twenty-three hips. Radiographic analysis of all twenty-nine hips that had not been revised showed loosening in one hip and a nonprogressive radiolucent line in one zone in two others. Kaplan-Meier analysis demonstrated a prosthetic survival rate, with aseptic loosening as the end point, of 90% at eight years.Conclusion: Acetabular revision with impaction bone-grafting and a cemented cup in patients with rheumatoid arthritis had acceptable results at an average of 7.5 years postoperatively.Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.


Acta Orthopaedica | 2009

Total ankle prostheses in rheumatoid arthropathy: Outcome in 52 patients followed for 1-9 years.

Huub J.L. van der Heide; Bernard Schutte; Jan Willem Louwerens; Frank H.J van den Hoogen; Maarten C. de Waal Malefijt

Background and purpose The first generations of total ankle replacements (TARs) showed a high rate of early failure. In the last decades, much progress has been made in the development of TARs, with the newer generation showing better results. We evaluated TARs implanted with rheumatoid arthritis (RA) or juvenile inflammatory arthritis (JIA) as indication. Patients and methods 58 total ankle prostheses (Buechel-Pappas and STAR type) were implanted in patients with RA (n = 53) or JIA (n = 5) in 54 patients (4 bilateral). After a mean follow-up of 2.7 (1–9) years, all patients were reviewed by two orthopedic surgeons who were not the surgeons who performed the operation. Standard AP and lateral radiographs were taken and a Kofoed ankle score was obtained; this is a clinical score ranging from 0–100 and consists of sub-scores for pain, disability, and range of motion. Results 2 patients died of unrelated causes. Of the 52 patients who were alive (56 prostheses), 51 implants were still in place and showed no signs of loosening on the most recent radiographs. The mean Kofoed score at follow-up was 73 points (SD 16, range 21–92). 4 patients showed a poor result (score < 50) with persistent pain for which no obvious reason could be found. 5 implants were removed, 4 because of infection and 1 because of aseptic loosening. Interpretation Medium-term results of the STAR and BP types of TAR in RA were satisfactory. The main reason for failure of the implant was infection.


Rheumatology | 2013

Treatment changes and improved outcomes in RA: an overview of a large inception cohort from 1989 to 2009

Wietske Kievit; Jaap Fransen; Maarten C. de Waal Malefijt; Alfons A. den Broeder; Piet L. C. M. van Riel

OBJECTIVE The introduction of effective treatment strategies in the past two decades has changed the management of RA dramatically. The objective was to analyse the changes in disease activity, function, joint damage and incidence of orthopaedic surgery over a period of 20 years (1989-2009) for patients with RA. METHODS Data acquired from 1989 to 2008 inclusive from the Nijmegen RA inception cohort were studied. By repeated measures analysis the course of the population mean disease activity score (DAS28) and the Health Assessment Questionnaire-Disability Index (HAQ-DI) corrected for age, gender, RF and disease duration was determined. Orthopaedic interventions were analysed as incidence rates with a Poisson distribution. We calculated the prevalence of the various therapies that patients were receiving. RESULTS By 2009, 992 patients with RA had been included and 273 had been excluded. From 1989 onwards, the proportion of patients using MTX increased from 5% (8 of 164) to 62% (486 of 780), and biologic response modifiers from 0% to 22% (168 of 780) in 2008. The average MTX dosage increased to 16.1 ± 5.5 mg/week in 2008. The mean DAS28 (3.1) and HAQ-DI (0.47) were least (P < 0.008) in 2008 compared with previous years. There was a significant trend towards lower incidence rates of orthopaedic intervention in the period 2006-2008 than in almost all previous years. CONCLUSION Treatment strategy changed in a large inception cohort of patients with RA which coincided with decreased disease activity, increased functional ability and fewer orthopaedic interventions since the early 1990s.


BMC Musculoskeletal Disorders | 2008

Hallux valgus angle as main predictor for correction of hallux valgus

Axel Deenik; Enrico de Visser; Jan-Willem K Louwerens; Maarten C. de Waal Malefijt; Frits F Draijer; Rob A. de Bie

BackgroundIt is recognized that different types of hallux valgus exist. Classification occurs with radiographic and clinical parameters. Severity of different parameters is used in algorithms to choose between different surgical procedures. Because there is no consensus about each parameter nor their cut-off point we conducted this study to analyze the influence of these variables on the postoperative hallux valgus angle.MethodsAfter informed consent 115 patients (136 feet) were included. Bunionectomy, osteotomy, lateralization of the distal fragment, lateral release and medial capsulorraphy were performed in all patients. Data were collected on preoperative and postoperative HVA, IMA and DMAA measurements. Forty cases were included since our findings in a previous article [1], therefore, current data concern an expanded study group with longer follow-up and were not published before. At least two-year follow-up data were evaluated with logistic regression and independent t-tests.ResultsPreoperative HVA was significant for prediction of postoperative HVA in logistic regression. IMA and DMAA were not significant for prediction of postoperative HVA in logistic regression, although they were significantly increased in larger deformities. In patients with preoperative HVA of 37 degrees or more, satisfactory correction could be obtained in 65 percent. The other nine of these 26 patients developed subluxation.ConclusionThe preoperative HVA was the main radiological predictor for correction of hallux valgus, correction rate declined from preoperative HVA of 37. IMA and DMAA did have a minor role in patients with preoperative HVA lower than 37 degrees, however, likely contributed to preoperative HVA of 37 degrees or more.


Acta Orthopaedica Scandinavica | 2011

Stemmed femoral knee prostheses

G Harry van Lenthe; Marieke M M Willems; Nico Verdonschot; Maarten C. de Waal Malefijt; R. Huiskes

Although the revision rates for modern knee prostheses have decreased drastically, the total number of revisions a year is increasing because many more primary knee replacements are being done. At the time of revision, bone loss is common, which compromises prosthetic stability. To improve stability, intra-medullary stems are often used. The aim of this study was to estimate the effects of a stem, its diameter and the interface bonding conditions on patterns of the bone remodeling in the distal femur. We created finite element models of the distal half of a femur in which 4 types of knee prostheses were placed. The bone remodeling process was simulated using a strain-adaptive bone remodeling theory. The amount of such remodeling was determined by calculating the changes in bone mineral density in 9 regions of interest from simulated DEXA scans. The computer simulation model showed that revision prostheses tend to cause more bone resorption than primary ones, especially in the most distal regions. Predicted long-term bone loss due to a revision prosthesis with a thin stem equalled that around a prosthesis with an intercondylar box. However, strong regional differences were found— the stemmed prostheses having more bone loss in the most distal areas and some bone gain in the more proximal ones. A prosthesis with a thick stem led to an increase in bone loss. When the prosthesis-cement interface was bonded, more bone loss was predicted than with an unbonded interface. These results suggest that a stem which increases stability initially may reduce stability in the long term. This is due to an increase in stress shielding and bone resorption.


Foot and Ankle Surgery | 2010

Conversion of failed ankle arthroplasty to an arthrodesis. Technique using an arthrodesis nail and a cage filled with morsellized bone graft.

Pieter H. J. Bullens; Maarten C. de Waal Malefijt; Jan Willem Louwerens

Arthrodesis of the ankle joint after a failed ankle prosthesis is most often demanding because of bone loss. The bone loss is also responsible for limb length discrepancy. Intramedullary nail fixation has been described to be successful for arthrodesis of the arthritic ankle joint. We report the use of the nail technique in combination with a morsellized bone graft in and around a cage to convert failed ankle prosthesis with bone loss into an arthrodesis. The advantages which were strived for include developing a more practical operative method with lower morbidity (no autograft), early mobilization and weight-bearing provided by the stability of the internal fixation and restoration of limb length.


Journal of Biomedical Materials Research Part B | 2010

The presence of periosteum is essential for the healing of large diaphyseal segmental bone defects reconstructed with trabecular metal: A study in the femur of goats

Pieter H. J. Bullens; H. W. Bart Schreuder; Maarten C. de Waal Malefijt; Nico Verdonschot; P. Buma

Large segmental diaphyseal bone defects can be reconstructed with massive structural allografts, but this technique is associated with high complication rates. Tantalum tabecular metal implants have been successfully used to restore bone defects associated with revision total knee or hip arthroplasties. The aim of this study was to investigate if tantalum cylinders could be used to reconstruct large load bearing segmental diaphyseal bone defects in the presence or absence of a periosteum coverage. Segmental bone defects were reconstructed with tantalum cylinders with or without preservation of the periosteum and stabilized by an intramedullary nail. Radiological analysis was performed postop and at 26 weeks follow-up. New bone was labeled with fluorochromes at 13 and 26 weeks follow-up. Reconstructions were tested mechanically and subsequently investigated histologically. Contra-lateral femurs were used as controls. Clinically all goats returned to normal functional loading after 2 weeks allowing unlimited weight bearing. Radiologically, all tantalum cylinders with periosteum coverage united with the host bone. Reconstructions with cylinders without periosteum coverage lead to radiological nonunion in five out of six cases. The strengths of the reconstruction with and without periosteum preservation were respectively 102.1% and 24.5% compared to controls. In the periosteum covered implants, bone contact was found at all levels of the tantalum cylinder and more and deeper bone ingrowth was found in this group. Tantalum cylinders seem a safe and reliable alternative for a massive cortical graft to reconstruct large diaphyseal bone defects in a goat model if healthy periosteum is present.


Anatomical Sciences Education | 2012

Loosely-guided, self-directed learning versus strictly-guided, station-based learning in gross anatomy laboratory sessions.

J.G.M. Kooloos; Maarten C. de Waal Malefijt; Dirk J. Ruiter; Marc A.T.M. Vorstenbosch

Anatomy students studying dissected anatomical specimens were subjected to either a loosely‐guided, self‐directed learning environment or a strictly‐guided, preformatted gross anatomy laboratory session. The current studys guiding questions were: (1) do strictly‐guided gross anatomy laboratory sessions lead to higher learning gains than loosely‐guided experiences? and (2) are there differences in the recall of anatomical knowledge between students who undergo the two types of laboratory sessions after weeks and months? The design was a randomized controlled trial. The participants were 360 second‐year medical students attending a gross anatomy laboratory course on the anatomy of the hand. Half of the students, the experimental group, were subjected without prior warning to station‐based laboratory sessions; the other half, the control group, to loosely‐guided laboratory sessions, which was the courses prevailing educational method at the time. The recall of anatomical knowledge was measured by written reproduction of 12 anatomical names at four points in time: immediately after the laboratory experience, then one week, five weeks, and eight months later. The strictly‐guided group scored higher than the loosely‐guided group at all time‐points. Repeated ANOVA showed no interaction between the results of the two types of laboratory sessions (P = 0.121) and a significant between‐subject effect (P ≤ 0.001). Therefore, levels of anatomical knowledge retrieved were significantly higher for the strictly‐guided group than for the loosely‐guided group at all times. It was concluded that gross anatomy laboratory sessions with strict instructions resulted in the recall of a larger amount of anatomical knowledge, even after eight months. Anat Sci Educ.

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Nico Verdonschot

Radboud University Nijmegen Medical Centre

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Pieter H. J. Bullens

Radboud University Nijmegen Medical Centre

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P. Buma

Radboud University Nijmegen

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Albert van Kampen

Radboud University Nijmegen

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R.P.H. Veth

Radboud University Nijmegen Medical Centre

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B. Willem Schreurs

Radboud University Nijmegen Medical Centre

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D. Wolfson

Radboud University Nijmegen Medical Centre

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Dennis Janssen

Radboud University Nijmegen

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