Jan Verhaar

Jan Verhaar
Erasmus MC | Erasmus MC · Department of Orthopaedics

MD, PhD

About

589
Publications
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25,038
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Additional affiliations
January 1995 - present
Erasmus MC
January 1995 - December 2015
Erasmus MC
Position
  • Professor (Full), Hed of Department

Publications

Publications (589)
Article
Objective: To assess whether initial non-operative treatment of anterior cruciate ligament (ACL) ruptures with optional delayed ACL reconstruction leads to more meniscal procedures compared with early ACL reconstruction during the 2-year follow-up. Methods: We compared the number of meniscal procedures of 167 patients with an ACL rupture, who ei...
Article
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Objective To explore the relationship between radiographic hip shape and features of early hip osteoarthritis (OA) on magnetic resonance imaging (MRI) in young male and female football players without radiographic hip OA. Design We used baseline data from a cohort of symptomatic and asymptomatic football players aged 18–50 years. Hip shape was ass...
Article
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Objective: To compare outcomes from arthroscopic partial meniscectomy versus physical therapy in young patients with traumatic meniscal tears. Methods: We conducted a multicentre, open-labelled, randomised controlled trial in patients aged 18-45 years, with a recent onset, traumatic, MRI-verified, isolated meniscal tear without knee osteoarthrit...
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Background Cartilage defects result in joint inflammation. The presence of proinflammatory factors has been described to negatively affect cartilage formation. Purpose To evaluate the effect and timing of administration of triamcinolone acetonide (TAA), an anti-inflammatory drug, on cartilage repair using a mouse model. Study Design Controlled la...
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Objective Inflammation is known to negatively affect cartilage repair. However, it is unclear how inflammation influences the migration of mesenchymal stromal cells (MSCs) from the underlying bone marrow into the defect. We therefore aimed to investigate how synovial inflammation influences MSC migration, and whether modulation of inflammation with...
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Objectives The aim of this study was to examine the effectiveness of an enhanced online injury prevention programme on the number of running-related injuries (RRIs) in recreational runners. Methods We conducted a randomised-controlled trial in runners who registered for running events (distances: 10–42.195 km) in the Netherlands. Adult runners who...
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The aim of this study was to determine the additional value of the false-profile (FP) view radiograph in the diagnosis of developmental dysplasia of the hip (DDH), as compared with an anteroposterior (AP) pelvic radiograph only, and evaluate the correlation between the Wiberg-lateral center edge angle (W-LCEA) and Wiberg-anterior center edge angle...
Article
Background The optimal treatment strategy for patients with an anterior cruciate ligament (ACL) rupture is still under debate. Different determinants of the need for a reconstruction have not been thoroughly investigated before. Purpose To investigate why, when, and which patients with an ACL rupture who initially started with rehabilitation thera...
Article
Objective: High-volume injections (HVIs) are thought to target neovascularization in chronic midportion Achilles tendinopathy (AT), yet the mechanism has not been clarified. Therefore, we aim to evaluate whether a HVI decreases ultrasonographic Doppler flow in patients with chronic midportion AT. Design: A double-blind, randomized, placebo-contr...
Conference Paper
Background The INSPIRE trial examined in 2017 the effect of an online injury prevention program on the number of running-related injuries (RRI). Although this program showed no effect on the number of injuries, new insights from this study were used to design an enhanced prevention program. Objective To examine the effectiveness of an online injur...
Article
Objective: To determine the minimal clinically important difference (MCID) for the Victorian Institute of Sport Assessment-Achilles (VISA-A) score in patients with midportion Achilles tendinopathy (AT). Design: Prospective cohort study. Methods: We included physically active patients with midportion AT who received exercises and an injection....
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Objective To assess the level of agreement between patient-reported pain using a standardized pain map and the physician-determined clinical diagnosis of Achilles tendinopathy. Design Cross-sectional study. Methods Eligible patients were adults visiting a sports physician for symptoms in the Achilles tendon region. Patients completed a digital qu...
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Debridement, antibiotics, and implant retention (DAIR) is a procedure to treat a periprosthetic joint infection (PJI) after total hip arthroplasty (THA) or total knee arthroplasty (TKA). The timing between the primary procedure and the DAIR is likely a determinant for its successful outcome. However, the optimal timing of a DAIR and the chance of s...
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Closed treatment of paediatric diaphyseal forearm fractures carries the risk of re-displacement, which can lead to symptomatic malunions. This is because growth will not correct angulation deformity as it does in metaphyseal fractures. The purpose of this prospective cohort study was to evaluate the outcomes after 3-D-planned corrective osteotomy w...
Chapter
The most important tool in the diagnosis and choice of treatment of orthopaedic disorders is medical history taking (anamnesis). Good medical history taking often leads to the correct diagnosis in a significant number of patients. The physical examination should further support this preliminary diagnosis, but the importance of a good medical histor...
Chapter
The physiotherapist and other paramedics play an important role in the treatment of musculoskeletal disorders and injuries. This applies not only to non-surgical (conservative) treatment but also perioperative treatment. The aim of the treatment is to support the patient returning to the highest possible level of functioning. In some patients, this...
Chapter
Osteoarthritis is characterised by loss of hyaline cartilage in a part of a synovial joint, together with changes in the (subchondral) bone directly beneath the cartilage and an inflammatory reaction of the synovial membrane of that joint. Osteoarthritis is further characterised by joint pain after loading, stiffness of the joint and restriction of...
Chapter
Because of its function and construction, the knee joint is one of the body’s most heavily loaded joints. It has great mobility with low intrinsic stability. In fact, the knee joint is really just a sphere (femur condyles) on a plate (tibia plate). The limited intrinsic stability must be compensated for by strong static ligaments (collateral ligame...
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Purpose The purpose of this study was to determine the effect of targeted eccentric calf muscle exercises compared to regular training on ankle dorsiflexion in healthy adolescent soccer players with a decreased ankle dorsiflexion. Methods Male adolescent players (aged 14–21 years) from two professional soccer clubs were evaluated with the Weight B...
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Background There is no consensus concerning the optimal casting technique for displaced distal radius fractures (DRFs) following closed reduction. This study evaluates whether a splint or a circumferential cast is most optimal to prevent fracture redisplacement in adult patients with a reduced DRF. Additionally, the cost-effectiveness of both cast...
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Objectives Groin injuries are common in professional male football and result in significant complaints, time-loss and cost. We aimed to study: 1. Normal values of hip muscle strength and self-reported hip and groin function (Hip And Groin Outcome Score (HAGOS)). 2. Changes in these values throughout the season. 3. If previous (groin) injuries, leg...
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Objectives To analyse whether 1) passive or active pain coping strategies and 2) presence of neuropathic pain component influences the change of Achilles tendinopathy (AT) symptoms over a course of 24 weeks in conservatively-treated patients. Design Prospective cohort study. Methods Patients with clinically-diagnosed chronic midportion AT were co...
Article
Objectives: To evaluate the impact of Achilles tendinopathy (AT) on quality of life (QoL), work performance, healthcare utilisation and costs in adults with conservatively treated chronic midportion AT. Methods: This cross-sectional survey-based study included 80 patients and took place in a sports medicine department of a large regional hospita...
Article
Due to typographic mistakes made by the editorial office, several corrections have been made. The original article has been corrected.
Article
A 52-year-old men suffered from osteoarthritis of the knee. During knee replacement surgery, the remaining cartilage appeared black. This discoloration and early degeneration of the cartilage is characteristic for the metabolic disorder alkaptonuria in which homogentisic acid accumulates in the body.
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Macrophages play an important role in the development and progression of osteoarthritis (OA). The aim of this study was to identify macrophage phenotypes in synovium and monocyte subsets in peripheral blood in C57BL/6 mice by destabilizing the medial meniscus (DMM), and the association of macrophage subsets with OA features. DMM, sham, and non‐oper...
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Mesenchymal stem cells (MSC) are promising candidates for use as a biological therapeutic. Since locally injected MSC disappear within a few weeks, we hypothesize that efficacy of MSC can be enhanced by prolonging their presence. Previously, encapsulation in alginate was suggested as a suitable approach for this purpose. We found no differences bet...
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Objective To summarize available evidence on the association between hip shape as quantified by statistical shape modeling (SSM) and the incidence or progression of hip osteoarthritis. Design We conducted a systematic search of five electronic databases, based on a registered protocol (available: PROSPERO CRD42020145411). Articles presenting origi...
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Background Achilles tendinopathy(AT) occurs in half of elite runners. AT is a difficult to treat tendon disease, which may progress from new‐onset to a chronic state. It is unknown how many runners with new‐onset AT develop persisting symptoms and which prognostic factors are associated with this course. Objective To describe how many runners deve...
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Purpose: The aim of this study was to (1) investigate whether radiographic and clinical parameters, which influence how stresses during sporting activities act on the proximal femur, are associated with cam morphology or (2) precede cam morphology development. Methods: Young male football players participated at baseline (n = 89, 12-19 years of...
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Introduction: Some scaphoid fractures become visible on radiographs weeks after a trauma which makes normal radiographs directly after trauma unreliable. Untreated scaphoid fractures can lead to scaphoid non-union progressing to osteoarthritis. Therefore, the general treatment for patients with a clinically suspected scaphoid fracture and normal i...
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Objective To study whether a high volume injection without corticosteroids improves clinical outcome in addition to usual care for adults with chronic midportion Achilles tendinopathy. Design Patient and assessor blinded, placebo controlled randomised clinical trial. Setting Sports medicine department of a large district general hospital, the Net...
Article
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Objectives To determine normal values for hip strength and range of motion (ROM) of elite, sub-elite and amateur male field hockey players and to examine the effect of age, leg dominance, playing position, playing level and non-time-loss groin pain on hip strength and ROM. Design Cross-sectional study. Setting Physical testing took place at field...
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Background Isometric exercises may provide an immediate analgesic effect in patients with lower‐limb tendinopathy and have been proposed as initial treatment and for immediate pain relief. Current evidence is conflicting and previous studies were small. Objective To study whether isometric exercises result in an immediate analgesic effect in patie...
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Background The alpha angle is the most often used measure to classify cam morphology. There is currently no agreement on which alpha angle threshold value to use. Purpose To systematically investigate the different alpha angle threshold values used for defining cam morphology in studies aiming to identify this threshold and to determine whether da...
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Background Conflicting and limited high quality prospective data is available on the associations between cam morphology and hip and groin symptoms and range of motion (ROM). Objectives This cross‐sectional cohort study investigated associations between cam morphology presence, size and duration and symptoms and ROM. Methods Academy male football...
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Abstract Objective To provide a consistently updated overview of the comparative effectiveness of treatments for Achilles tendinopathy. Design Living systematic review and network meta-analysis. Data sources Multiple databases including grey literature sources were searched up to February 2019. Study eligibility criteria Randomised controlled trial...
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Introduction Running-related injuries (RRIs) are frequent, but no effective injury prevention measures have been identified yet. Therefore, we have set up the INSPIRE trial in 2017, in which the effectiveness of an online injury prevention programme was tested. Although this programme was not effective in reducing the number of RRIs, we gained new...
Article
Full-text available
Objective: To examine the effect of a multifactorial, online injury prevention programme on the number of running-related injuries (RRIs) in recreational runners. Methods: Adult recreational runners who registered for a running event (distances 5 km up to 42.195 km) were randomised into the intervention group or control group. Participants in th...
Article
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We report a rare case of C. krusei knee arthritis treated with instillation of micafungin and arthroscopy. A 49-year-old man hospitalized for treatment of Acute Myeloid Leukemia developed knee arthritis with C. krusei. He was treated with a combination of arthroscopic debridement, intravenous as well as intra-articular micafungin. Serum and intra-a...
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Objectives: To determine the incidence of Achilles tendinopathy in a large group of recreational runners and to determine risk factors for developing AT. Design: Observational cohort study. Methods: Runners registering for running events (5-42 km) in the Netherlands were eligible for inclusion. Main inclusion criteria were: age ≥18 years, and...
Article
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Objectives: Ultrasound assessments of patients with chronic midportion Achilles tendinopathy include determining the degree of neovascularization using Doppler flow. A frequently used measure to quantify neovascularization is the modified Öhberg score. It is unknown whether the semiquantitative modified Öhberg score (0-4+) has higher reliability t...
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Background: Computer Assisted Surgery (CAS) has proven to improve the accuracy in several orthopedic procedures. Therefore we used this technique to evaluate femoral component positioning in Hip Resurfacing Arthroplasty (HRA). The aim of this study was to evaluate imageless CAS compared to manually implanted femoral components and subsequently eva...
Article
Objective: Synovium contains multipotent progenitor/stromal cells (MPCs) with potential to participate in cartilage repair. Understanding the identity of these MPCs will allow their therapeutic potential to be fully exploited. Hence this study aimed to identify primary synovial MPCs and characterize them in the context of cartilage regeneration....
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Background: Aging is known to induce immunosenescence, resulting in alterations in both the innate and adaptive immune system. Here we evaluated the effects of aging on B cell subsets in peripheral blood of 155 immunologically healthy individuals in four age categories (range 20-95y) via multi-parameter flow cytometry. Furthermore, we studied the...
Article
Inleiding Verschillende internationale richtlijnen adviseren een intra-articulaire corticosteroïdinjectie bij pijnlijke heupartrose, maar de systemische werking van corticosteroïden bij heupartrose is onbekend. Wij onderzochten of intramusculaire corticosteroïdinjecties de pijn kunnen verminderen en vergeleken deze met placebo-injecties. Methode In...
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Background: A congenital forearm pseudarthrosis is a rare condition and is strongly associated with neurofibromatosis type 1. Several surgical techniques are described in the literature, but the most optimal treatment strategy remains unclear. This systematic review aims to develop a treatment algorithm that may aid in clinical decision making. M...
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Background High molecular weight (HMW) hyaluronic acid (HA) is a treatment option for knee osteoarthritis (OA). The efficacy of HMW-HA in knee OA is investigated extensively, but the effectiveness in patients in the working age is unknown. Nevertheless, the number knee OA patients in the working age is increasing. Surgical treatment options are les...
Chapter
De orthopedisch chirurg is getraind om met operatieve ingrepen letsels of aandoeningen van het bewegingsstelsel te behandelen. De operatieve behandeling is vaak de eindfase van een behandeling die start met niet-operatieve (‘conservatieve’) behandeling. Fysiotherapie, gipsbehandeling, gebruik van braces, voorschrijven van pijnstillers en toedienen...
Chapter
Artrose is een aandoening die gekarakteriseerd wordt door het verlies van kraakbeen in een deel van een synoviaal gewricht met daarnaast veranderingen in het direct onder kraakbeen gelegen (subchondrale) bot en een ontstekingsreactie van de synoviale membraan. Artrose wordt gekenmerkt door gewrichtspijn na belasting en door stijfheid en bewegingsbe...
Chapter
Na anamnese en lichamelijk onderzoek ontstaat een waarschijnlijkheidsdiagnose die verder onderbouwd moet worden met aanvullend onderzoek. In dit hoofdstuk komen de meest gebruikte technische onderzoeken in de orthopedie aan de orde. Radiologisch onderzoek staat centraal. De ‘gewone” röntgenfoto is nog steeds het werkpaard van de diagnostiek. Ook CT...
Chapter
Het kniegewricht heeft een belangrijke rol bij onze activiteiten en wordt dus zwaar belast, heeft een grote bewegingsuitslag en een beperkte intrinsieke stabiliteit. Dat maakt het gewricht kwetsbaar voor letsels waarbij meniscus, kraakbeen en collateraal en gewrichtsbanden beschadigd kunnen raken. De meniscus speelt een belangrijke rol. Behoud van...
Chapter
Fysiotherapie vervult een niet weg te denken rol in orthopedische behandeling. Bij de conservatieve behandeling van letsels en aandoeningen is fysiotherapie vaak essentieel en na operaties is de fysiotherapeut een belangrijk lid van het behandelteam. Bewegingstherapie staat centraal in elk herstelprogramma. Dit bestaat afhankelijk van de aandoening...
Chapter
In dit eerste hoofdstuk van het Leerboek orthopedie wordt het belang van een zorgvuldige anamnese en lichamelijk onderzoek beschreven; op basis hiervan is het meestal mogelijk om een goede differentiaaldiagnose op te stellen. Achtereenvolgens wordt in woord en beeld de terminologie besproken die gebruikt wordt om de bewegingen van de verschillende...
Article
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Background Achilles tendinopathy is a common problem, but its exact aetiology remains unclear. Objective To evaluate the association between potential clinical risk factors and Achilles tendinopathy. Design Systematic review. Data sources The databases Embase, MEDLINE Ovid, Web of Science, Cochrane Library and Google Scholar were searched up to...
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Background and purpose — It has been hypothesized that hospitals and surgeons with high caseloads of hip fracture patients have better outcomes, but empirical studies have reported contradictory results. This systematic review and meta-analysis evaluates the volume–outcome relationship among patients with hip fracture patients. Methods — A search o...