Publications by authors named "Johan van der Stok"

Dual mobility total joint arthroplasty is gaining popularity for trapeziometacarpal joint (TMCJ) arthritis, with evolving indications, surgical technique and rehabilitation. The aim of this study was to obtain detailed insight into the variations in indications, surgical technique and rehabilitation for TMCJ arthroplasty with dual mobility implants, across a large international cohort of surgeons. The secondary aim was to analyse if there were differences in TMCJ arthroplasty between highly and less experienced surgeons.

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Background: Isolated osteoarthritis of the lateral compartment of the knee is less common than that of the medial compartment, resulting in significantly fewer lateral unicompartmental knee arthroplasties (UKAs) being performed. This study aimed to evaluate results of a fixed-bearing UKA for the treatment of lateral compartment osteoarthritis of the knee.

Methods: A prospectively collected cohort of 255 patients undergoing fixed-bearing UKA of the lateral compartment using the Triathlon PKR (Stryker, Warsaw, IND) implant with a minimum 2-year follow-up was reviewed.

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Background: Focal chondral defects (FCDs) of the femoral condyle are common. Treatment has heretofore primarily consisted of non-surgical and biological treatments. Focal articular surface replacement (FASR) is an emerging technique utilizing small implants to essentially fill the FCD.

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Article Synopsis
  • The study evaluated the effectiveness and long-term survival of the HemiCAP device for treating focal femoral condyle chondral and osteochondral defects in 266 patients with a mean follow-up of 7.3 years.
  • Significant improvements in clinical score values were observed post-surgery compared to preoperative values, though age influenced some outcomes.
  • The procedure has a high survival rate of 96.2% at 10 years, indicating it is a viable option whether performed as a primary treatment or after previous cartilage surgeries.
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Background: Despite the fact that primary adhesive capsulitis of the glenohumeral joint is often considered a self-limiting condition, not all patients make a full recovery. Manipulation under anesthesia (MUA) is performed to forcibly rupture the contracted capsule in a controlled manner. However, the technique, timing, and use of additional injections are often debated.

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We studied the three-dimensional (3-D) shape variations and symmetry of the lunate to evaluate whether a contralateral shape-based approach to design patient-specific implants for treatment of Kienböck's disease is accurate. A 3-D statistical shape model of the lunate was built using the computed tomography scans of 54 lunate pairs and shape symmetry was evaluated based on an intraclass correlation analysis. The lunate shape was not bilaterally symmetrical in (1) the angle scaphoid surface - radius-ulna surface, (2) the dorsal side and the length of the side adjacent to the triquetrum, (3) the orientation of the volar surface, (4) the width of the side adjacent to the scaphoid, (5) the skewness in the coronal plane and (6) the curvature of bone articulating with the hamate and capitate.

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Background: Focal articular lesions of the knee can be treated using several different techniques with generally good results, but failures are difficult to manage. Focal articular surface replacement (FASR) using metal implants could be a promising technique that allows defect geometry matching, congruency restoration and defect propagation prevention.

Methods: 132 patients were included who underwent FASR between January 2009 and December 2013.

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Surgery of long bone metastases is associated with a significant risk of perioperative blood loss, which may necessitate blood transfusion.Successful embolization (> 70% obliteration of vascularity) can be achieved in 36-75% of cases.The reported rate of embolization-related complications is 0-9%.

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A promising bone graft substitute is porous titanium. Porous titanium, produced by selective laser melting (SLM), can be made as a completely open porous and load-bearing scaffold that facilitates bone regeneration through osteoconduction. In this study, the bone regenerative capacity of porous titanium is improved with a coating of osteostatin, an osteoinductive peptide that consists of the 107-111 domain of the parathyroid hormone (PTH)-related protein (PTHrP), and the effects of this osteostatin coating on bone regeneration were evaluated in vitro and in vivo.

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The medical device industry's interest in open porous, metallic biomaterials has increased in response to additive manufacturing techniques enabling the production of complex shapes that cannot be produced with conventional techniques. Tantalum is an important metal for medical devices because of its good biocompatibility. In this study selective laser melting technology was used for the first time to manufacture highly porous pure tantalum implants with fully interconnected open pores.

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The large surface area of highly porous titanium structures produced by additive manufacturing can be modified using biofunctionalizing surface treatments to improve the bone regeneration performance of these otherwise bioinert biomaterials. In this longitudinal study, we applied and compared three types of biofunctionalizing surface treatments, namely acid-alkali (AcAl), alkali-acid-heat treatment (AlAcH), and anodizing-heat treatment (AnH). The effects of treatments on apatite forming ability, cell attachment, cell proliferation, osteogenic gene expression, bone regeneration, biomechanical stability, and bone-biomaterial contact were evaluated using apatite forming ability test, cell culture assays, and animal experiments.

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The design of bioactive three-dimensional (3D) scaffolds is a major focus in bone tissue engineering. Incorporation of growth factors into bioprinted scaffolds offers many new possibilities regarding both biological and architectural properties of the scaffolds. This study investigates whether the sustained release of bone morphogenetic protein 2 (BMP-2) influences osteogenicity of tissue engineered bioprinted constructs.

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Porous titanium scaffolds are a promising class of biomaterials for grafting large bone defects, because titanium provides sufficient mechanical support, whereas its porous structure allows bone ingrowth resulting in good osseointegration. To reinforce porous titanium scaffolds with biological cues that enhance and continue bone regeneration, scaffolds can be incorporated with bioactive gels for time- and dose-controlled delivery of multiple growth factors (GFs). In this study, critical femoral bone defects in rats were grafted with porous titanium scaffolds incorporated with nanostructured colloidal gelatin gels.

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In the present study, two open porous calcium phosphate ceramics, β-tricalcium phosphate (β-TCP), and hydroxyapatite (HA) were compared in a critical-sized femoral defect in rats. Previous comparisons of these two ceramics showed significantly greater osteoinductive potential of β-TCP upon intramuscular implantation and a better performance in a spinal fusion model in dogs. Results of the current study also showed significantly more bone formation in defects grafted with β-TCP compared to HA; however, both the ceramics were not capable of increasing bone formation to such extend that it bridges the defect.

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Mesenchymal stromal cells (hMSCs) are advancing into the clinic but the therapeutic efficacy of hMSCs faces the problem of donor variability. In bone tissue engineering, no reliable markers have been identified which are able to predict the bone-forming capacity of hMSCs prior to implantation. To this end, we isolated hMSCs from 62 donors and characterized systematically their in vitro lineage differentiation capacity, gene expression signature and in vivo capacity for ectopic bone formation.

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There is a growing interest in studying the fracture behavior of bones, primarily due to the increasing societal burden of osteoporotic fractures. In addition, bone is one of the most important biological materials whose fracture behavior is not yet well understood. This is partly due to the fact that bone is a complex hierarchical material, and exhibits heterogeneous, anisotropic, and viscoelastic mechanical behavior.

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Porous titanium scaffolds have good mechanical properties that make them an interesting bone substitute material for large bone defects. These scaffolds can be produced with selective laser melting, which has the advantage of tailoring the structure's architecture. Reducing the strut size reduces the stiffness of the structure and may have a positive effect on bone formation.

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The efficacy of calcium phosphate (CaP) ceramics in healing large bone defects is, in general, not as high as that of autologous bone grafting. Recently, we reported that CaP ceramics with osteoinductive properties were as efficient in healing an ilium defect of a sheep as autologous bone graft was, which makes this subclass of CaP ceramics a powerful alternative for bone regeneration. Although osteoinduction by CaP ceramics has been shown in several large animal models it is sporadically reported in mice.

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Autologous bone grafting is currently considered as the gold standard to restore bone defects. However, clinical benefit is not guaranteed and there is an associated 8-39% complication rate. This has resulted in the development of alternative (synthetic) bone substitutes.

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Proper heart function relies on high efficiency of energy conversion. Mitochondrial oxygen-dependent processes transfer most of the chemical energy from metabolic substrates into ATP. Healthy myocardium uses mainly fatty acids as its major energy source, with little contribution of glucose.

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