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Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_4 | Pages 79 - 79
1 Mar 2021
Doodkorte R Roth A van Rietbergen B Arts J Lataster L van Rhijn L Willems P
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Complications after spinal fusion surgery are common, with implant loosening occurring in up to 50% of osteoporotic patients. Pedicle screw fixation strength reduces as a result of decreased trabecular bone density, whereas sublaminar wiring is less affected by these changes. Therefore, pedicle screw augmentation with radiopaque sublaminar wires (made with Dyneema Purity® Radiapque fibers, DSM Biomedical, Geleen, the Netherlands) may improve fixation strength. Furthermore, sublaminar tape could result in a gradual motion transition to distribute stress over multiple levels and thereby reduce implant loosening. The objective of this study is to test this hypothesis in a novel experimental setup in which a cantilever bending moment is applied to individual human vertebrae.

Thirty-eight human cadaver vertebrae were stratified into four different groups: ultra-high molecular weight polyethylene sublaminar tape (ST), pedicle screw (PS), metal sublaminar wire (SW) and pedicle screw reinforced with sublaminar tape (PS+ST). The vertebrae were individually embedded in resin, and a cantilever bending moment was applied bilaterally through the spinal rods using a universal material testing machine. This cantilever bending setup closely resembles the loading of fixators at transitional levels of spinal instrumentation.

The pull-out strength of the ST (3563 ± 476N) was not significantly different compared to PS, SW or PS+ST. The PS+ST group had a significantly higher pull-out strength (4522 ± 826N) compared to PS (2678 ± 292N) as well as SW (2931 ± 250N).

The higher failure strength of PS + ST compared to PS indicates that PS augmentation with ST may be an effective measure to reduce the incidence of screw pullout, even in osteoporotic vertebrae. Moreover, the lower stiffness of sublaminar fixation techniques and the absence of damage to the cortices in the ST group suggest that ST as a stand-alone fixation technique in adult spinal deformity surgery may also be clinically feasible and offer clinical benefits.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_11 | Pages 30 - 30
1 Dec 2020
Haartmans M Eveque-Mourroux M Eijkel G Emanuel K Tuijthof G van Rhijn L Heeren R Emans P Cillero-Pastor B
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The incidence of osteoarthritis (OA) is increasing in our younger population. OA development early in life is often related to cartilage damage, caused by (sport) injury or trauma. Detection of early knee OA is therefore crucial to target early treatment. However, early markers for OA prognosis or diagnosis are lacking. Hoffa's fat pad (HFP) is an emerging source for knee biomarkers, as it is easily accessible and shows important interaction with the homeostasis of the knee. In this study, we used Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) as a first approach. MALDI-MSI allows the study of tissue-specific molecular distributions. Therefore, we used MALDI-MSI to analyze the lipid profiles in the HFP of three patients with OA and three patients undergoing cartilage regenerative treatment. We demonstrate that the lipid profile of patients with OA is different from patients with cartilage defects.

HFP of each patient were snap frozen directly after surgical resection and cryosectioned at 15 μm. Each slide was sublimed with Norharmane matrix and analyzed by MALDI-MSI in positive and negative ion modes at a lateral resolution of 50 μm on a RapifleX Tissue Typer. The difference between patient groups were analyzed using principle component analysis and linear discriminant analysis. Lipid identifications were obtained on an Orbitrap Elite™ Hybrid Ion Trap-Orbitrap Mass Spectrometer in data dependent acquisition mode and analyzed using Lipostar software.

Linear discriminant analysis showed a specific lipid profile for each group (variance 33.94%). Score projections revealed a differential lipid spatial distribution of OA patients compared to cartilage defect patients. Among the lipids that differed significantly, for instance, the m/z 760.59 [M+H]+ was associated to osteoarthritis and identified as glycerophospholipid (PC 34:1), a main component of biological membranes. Additionally, the samples were found to be intra-tissue heterogeneous, with molecular profiles found in adipose-, connective- and synovial tissue.

These results suggest that lipid profiles in HFP could be useful for early OA detection. However, intra-tissue heterogeneity in HFP should be recognized when using HFP as a biomarker source.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_3 | Pages 18 - 18
1 Apr 2018
Caron M Janssen M Peeters L Surtel D van Rhijn L Emans P Welting T
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INTRODUCTION

The generation of cartilage from progenitor cells for the purpose of cartilage repair is often hampered by unwanted hypertrophic differentiation of the generated tissue due to endochondral ossification. Continuing on our earlier studies, our goal is to further improve the engineering of hyaline cartilage for the treatment of a cartilage defect in our in vivo model for subperiosteal generation of cartilage, by tuning the differentiation status of the generated cartilage and prevent hypertrophic differentiation. As a healthy cartilage matrix contains high amounts of aggrecan we hypothesise that aggrecan supplementation of the bio-gel used in the generation of the subperiosteal cartilage, mimics the composition of the extracellular matrix environment of cartilage with potential beneficial properties for the engineered cartilage.

METHODS

A 2% (m/v) low melting agarose was injected between the bone and periosteum at the upper medial side of the tibia of both legs of New Zealand white rabbits (DEC 2012–151). The agarose was left unloaded (n=7) or supplemented (n=7) with 2% (w/v) bovine aggrecan (Sigma-Aldrich). After 14 days, rabbits were euthanised. Generated subperiosteal cartilage tissue was analysed for weight, GAG and DNA content. In addition, RT-qPCR and (immuno)histochemistry was performed for key markers of different phases of endochondral ossification.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_3 | Pages 21 - 21
1 Apr 2018
Caron M Castermans T van Rietbergen B Haartmans M van Rhijn L Witlox A Welting T
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INTRODUCTION

Endochondral ossification in the growth plate is directly responsible for skeletal growth and its de novo bone-generating activity. Growth plates are vulnerable to disturbances that may lead to abnormal skeletal development. Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used analgesics but have been reported to impair endochondral ossification-driven fracture healing. Despite the general awareness that NSAIDs affect endochondral ossification, the consequences of NSAIDs on skeletal development are unknown. We hypothesise that the NSAID celecoxib leads to impaired growth plate development and consequently impairs skeletal development.

METHODS

Healthy skeletally immature (5 weeks old) C57BL/6 mice were treated for ten weeks with celecoxib (daily oral administration 10 mg/kg) or placebo (water) (institutional approval 2013–094) (n=12 per group). At 15 weeks postnatally, total growth plate thickness, the thickness of specific growth plate zones, (immuno)histological analysis of extracellular matrix composition in the growth plate, cell number and cell size, longitudinal bone growth and bone micro-architecture by micro-CT were analysed. Inhibition of COX-2 activity was confirmed by determining PGE2 levels in plasma using an ELISA.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_4 | Pages 25 - 25
1 Apr 2018
de Bot R Stevens J Hermus J Staal H van Rhijn L Witlox A
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Purpose

Flat feet are an important cause of foot problems in children. The flexible flat foot is the most common form and is normally physiological and asymptomatic. Further assessment is necessary when a symptomatic flat foot persists. Surgical interventions are indicated when conservative therapies have failed. The Kalix arthroereisis is a surgical option and is placed in the subtalar joint of the foot, thereby preventing hyperpronation, and stabilizes the foot against excessive movements. The purpose of this study was to evaluate the functional and radiological outcomes of pediatric patients who had undergone a Kalix implantation for the treatment of a symptomatic flexible flat foot.

Methods

Patient files of our institution were searched for patients who underwent a Kalix implantation between 2009 and 2014. Sixteen patients (26 feet) with symptomatic flexible flat feet were clinically and radiographically evaluated in this retrospective study. The calcaneal pitch and Meary”s angle were measured on the pre-, and postoperative follow-up radiographs and patient satisfaction survey was performed at follow-up to gain insight into functional outcome and satisfaction after the intervention.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_3 | Pages 33 - 33
1 Apr 2018
Timur UT Emans P van Rhijn L Welting T
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Introduction

Cartilage homeoprotein 1 (CART-1) is a homeoprotein which has been suggested to play a role in chondrocyte differentiation and in skeletal development. It is expressed mainly in prechondrocytic mesenchymal condensations. Patients with mutations in the CART-1 gene display several craniofacial abnormalities, suggesting that CART-1 has a functional role in craniofacial skeletal development. However, its target genes and position in the established chondrogenic pathways is poorly documented. Given the fact that CART-1 is expressed predominantly in the chondrocyte lineage and its role in skeletal development, we hypothesized that CART-1 regulates expression of several pivotal genes involved in chondrogenic differentiation.

Methods

The coding sequence of human CART-1 was custom synthesized with optimized codon usage and cloned into a p3XFLAG-CMV-7.1 expression vector. FLAG-CART-1 was transiently overexpressed in SW1353 cells by polyethyleneimine-mediated transfection (1,000 ng of plasmid/well in 12-well plates). FLAG-Empty vector was used as a negative control. FLAG-CART-1 overexpression was confirmed by means of anti-FLAG immunoblotting. To investigate a potential connection between CART-1 and established key chondrogenic pathways, TGFβ3 (10 ng/mL) was added to SW1353 cells in CART-1 overexpression cultures or their appropriate controls. Cells were harvested 48 hours after transfection and mRNA expression of several genes involved in chondrogenic differentiation was determined by qRT-PCR. Data represent three separate experiments performed in technical triplicate.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_4 | Pages 78 - 78
1 Apr 2018
Caron M Janssen M Peeters L Surtel D Koole L van Rhijn L Welting T Emans P
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INTRODUCTION

The generation of cartilage from progenitor cells for the purpose of cartilage repair is often hampered by unwanted ossification of the generated tissue due to endochondral ossification. Our in vitro data show that celecoxib is able to suppress the hypertrophic differentiation phase of endochondral ossification in differentiating human bone marrow stem cells via inhibition of prostaglandin signalling. Continuing on our earlier studies our goal is to further improve the engineering of hyaline cartilage for the treatment of cartilage defects, by determining if celecoxib released from poly(D,L-lactic acid)microspheres is able to prevent unwanted ossification in an in vivo model for the subperiosteal cartilage generation.

METHODS

A 2% (m/v) low melting agarose was injected between the bone and periosteum at the upper medial side of the tibia of both legs of New Zealand white rabbits (DEC 2012–151). The agarose was left unloaded or (n=8) or loaded (n=7) with celecoxib-loaded PGLA microspheres (poly(D,L-lactic acid) microspheres were loaded with 20% (w/w) Celecoxib (Pfizer)). Fourteen days post-injection, rabbits were euthanised. The developed subperiosteal cartilage tissue was analysed for weight, GAG and DNA content. In addition, RT-qPCR and (immuno)histochemistry were performed for key markers of different phases of endochondral ossification.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_4 | Pages 79 - 79
1 Apr 2018
Timur UT Caron M Welting T van Rhijn L Emans P Jahr H
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Introduction

In vitro expansion of human articular chondrocytes (HACs) is required for cell-based strategies to treat cartilage defects. We have earlier shown that culturing HACs at increased osmolarity (i.e., 380 mOsm), as compared to plasma osmolarity (i.e., 280 mOsm), increases collagen type II (COL2A1) expression in vitro. Our earlier results showed that knockdown of TGF-β2, a prototypic member of the TGF-β superfamily and an accepted key regulator of chondrocyte differentiation, resulted in increased COL2A1 production. BMPs are members of the TGF-β superfamily which are known to be involved in the regulation of COL2A1 expression. In this study, we aimed to elucidate the role of BMP signaling, in the upregulation of COL2 production upon TGF-β2 knockdown (KD) under hyperosmotic culture conditions.

Methods

HACs from five OA patients (passage 1) were cultured in cytokine-free medium, under 280 or 380 mOsm respectively, under standard 2D in vitro conditions. TGF-β2 knockdown (KD) by siRNA was performed in the presence or absence of the established bone morphogenetic protein (BMP) type I receptor (BMPRI) inhibitor dorsomorphin (10 μM). Expression of COL2A1 was evaluated by qRT-PCR.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_3 | Pages 40 - 40
1 Apr 2018
Roth A van der Meer R Willems P van Rhijn L Arts J Ito K van Rietbergen B
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INTRODUCTION

Growth-guidance constructs are an alternative to growing rods for the surgical treatment of early onset scoliosis (EOS). In growth-guidance systems, free-sliding anchors preserve longitudinal spinal growth, thereby eliminating the need for surgical lengthening procedures. Non-segmental constructs containing ultra-high molecular weight polyethylene (UHMWPE) sublaminar wires have been proposed as an improvement to the traditional Luque trolley. In such a construct, UHMWPE sublaminar wires, secured by means of a knot, serve as sliding anchors at the proximal and distal ends of a construct, while pedicle screws at the apex prevent rod migration and enable curve derotation. Ideally, a construct with the optimal UHMWPE sublaminar wire density, offering the best balance between providing adequate spinal fixation and minimizing surgical exposure, is designed preoperatively for each individual patient. In a previous study, we developed a parametric finite element (FE) model that potentially enables preoperative patient-specific planning of this type of spinal surgery. The objective of this study is to investigate if this model can capture the decrease in range of motion (ROM) after spinal fixation as measured in an experimental study.

MATERIALS AND METHODS

In a previous in vitro study, the ROM of an 8-segment porcine spine was measured before and after instrumentation, using different instrumentation constructs with a sequentally decreasing number of wire fixation points. In the current study, the parametric FE model of the thoracolumbar spine was first validated relative to ROM values reported in the literature. The rods, screws, and sublaminar wires were implemented, and the model was subsequently used to replicate the in vitro tests. The experimental and simulated ROM”s for the different instrumentation conditions were compared.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_2 | Pages 108 - 108
1 Jan 2017
Stevens J Welting T Witlox A van Rhijn L Staal H
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Dysplasia Epiphysealis Hemimelica (DEH) also known as Trevor's Disease is a rare developmental disorder resulting in cartilaginous overgrowth of the epiphysis of long bones. DEH is usually diagnosed in children between two and eight years old and it is three times more often diagnosed in boys. The most reported complaints are pain, limitation in range of motion, and deformity or swelling of the affected joint. Treatment of symptomatic lesions consists of surgical resection of the lesion, resulting in good long-term results.

Based on histological evaluation, DEH is often described as an osteochondroma or an osteochondroma-like lesion, although there are clinical, radiological and genetic differences between DEH and osteochondromas. To investigate the hypothesis that DEH and osteochondromas are histologically identical, two cases of DEH and two cases of osteochondromas in patients with Hereditary Multiple Osteochondroma (HMO) are compared at histological level.

Tissue samples from patients with a histopathologically confirmed diagnosis of DEH were compared with two age and gender matched patients diagnosed with HMO. After tissue sampling and processing, (immuno)histological stainings were performed for Collagen type II, Collagen type X, Sox-9 and Safranin-O.

Histologically, clumping of chondrocytes in a fibrillar matrix, a thick disorganized cartilage cap and ossification centres with small amounts of unresorbed cartilage were observed in DEH. In contrast, chondrocyte organisation in cartilage of osteochondromas displays characteristics of the normal growth plate. In addition, differences in expression of collagen type II, collagen type X and Sox9 were observed. Collagen type II was expressed in the extracellular matrix surrounding proliferative and hypertrophic chondrocytes in osteochondromas, while weak expression was observed in the entire cartilage cap in DEH. Collagen type X was not expressed in DEH, while expressed in the pericellular matrix surrounding hypertrophic chondrocytes in osteochondromas. Staining for Sox9 was positive in the hypertrophic chondrocytes in osteochondromas, while expressed in the nuclei of all chondrocyte clusters in DEH.

Both morphological and immunohistological differences were observed in histological sections of DEH and osteochondromas. These findings reject our hypothesis, and supports the earlier observed clinical, radiological and genetic differences and implies a different aetiology between DEH and osteochondroma formation in HMO.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_1 | Pages 70 - 70
1 Jan 2017
Peters M Brans B Wierts R Jutten L Weijers T Broos W Mottaghy F van Rhijn L Willems P
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The clinical success of posterior lumbar interbody fusion (PLIF) may be limited by pseudarthrosis, defined as the absence of solid fusion 1 year after surgery. Currently, CT is used to diagnose pseudarthrosis but is not able to be conclusive earlier than 1 year after surgery. No non-invasive technique is available to reliably assess bone graft incorporation in the early phase after PLIF.

Positron Emission Tomography (PET) is a nuclear imaging modality that is able to identify changes at the cellular and molecular level in an early stage, well before manifestation of anatomical changes. PET/CT with the bone seeking tracer 18F-fluoride allows localization and quantification of bone metabolism.

This study investigates whether an 18F-fluoride PET/CT scan early after PLIF is able to predict the fusion status at 1 year postoperative on CT.

Twenty patients after PLIF were enrolled after written informed consent. At 6 weeks and at 1 year after PLIF, intravenous injection of 18F-fluoride was followed by a static scan at 60 minutes (Philips, Gemini TF PET/CT). Processing of images resulted in a bone metabolism parameter i.e. standardized uptake value (SUV). This parameter was determined for 3 regions of interest (ROIs): the intervertebral disc space (IDS) and the upper and lower endplate (UE and LE, respectively) of the operated segment.

Interbody fusion was scored on a diagnostic CT scan made 1 year postoperatively and was defined as the amount of complete bony bridges between vertebrae, i.e 0, 1 or 2. Based on these scores, patients were divided in either the pseudarthrosis group (score 0) or the fusion group (scores 1 and 2). Differences between groups were analyzed using the independent samples Mann-Whitney U-test.

Ten patients were classified as pseudarthrosis (0 bridges: n=10) and 10 patients as fused (1 bridge: n=5, 2 bridges: n=5).

Patients in the pseudarthrosis group showed significantly lower bone metabolism values in the IDS on the 6 weeks PET/CT scan compared to patients in the fusion group (SUVIDS,6w13.3±5.62 for pseudarthrosis and 22.6±6.42 for the fusion group, p=0.003), whereas values at the endplates were similar (SUVUE,6w20.3±5.85 for pseudarthrosis and 21.6±4.24 for the fusion group, p=0.282). Furthermore, only in the pseudarthrosis group, bone metabolism in the IDS was significantly lower than at the endplates (p=0.006). In the fusion group, bone metabolism in the IDS and at the endplates was similar (p=0.470).

The PET/CT scan at 1 year postoperative showed that in the pseudarthrosis group, bone metabolism of the IDS remained lower compared to the endplates (SUVIDS,1y13.2±4.37, SUVUE,1y16.4±5.33, p=0.004), while in the fusion group, IDS and endplate bone metabolism was similar (SUVIDS,1y13.6±2.91, SUVUE,1y14.4±3.14, p=0.397).

This study shows that low bone metabolism values in the IDS of the operated segment as seen on 18F-fluoride PET/CT 6 weeks after PLIF, is related to development of pseudarthrosis 1 year postoperatively. These results suggest that 18F-fluoride PET/CT might be an early diagnostic tool to identify patients prone to develop pseudarthrosis after PLIF.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_2 | Pages 72 - 72
1 Jan 2017
Caron M Emans P Cremers A Surtel D van Rhijn L Welting T
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Heterotopic ossi?cation is the abnormal formation of bone in soft tissues and is a frequent complication of hip replacement surgery. Heterotopic ossi?cations are described to develop via endochondral ossification and standard treatment is administration of indomethacin. It is currently unknown how indomethacin influences heterotopic ossi?cation on a molecular level, therefore we aimed to determine whether indomethacin might influence heterotopic ossi?cation via impairing the chondrogenic phase of endochondral ossification.

ATDC5, human bone marrow stem cells (hBMSCs) and rabbit periosteal agarose cultures were employed as progenitor cell models; SW1353, human articular chondrocytes and differentiated ATDC5 cells were used as matured chondrocyte cell models. All cells were cultured in the presence of (increasing) concentrations of indomethacin. The action of indomethacin was confirmed by decreased PGE2 levels in all experiments, and was determined by specific PGE2 ELISA. Gene- and protein expression analyses were employed to determine chondrogenic outcome.

Progenitor cell models differentiating in the chondrogenic lineage (ATDC5, primary human bone marrow stem cells and ex vivo periosteal agarose cultures) were treated with increasing concentrations of indomethacin and a dose-dependent decrease in gene- and protein expression of chondrogenic and hypertrophic markers as well as decreased glycosaminoglycan content was observed. Even when hypertrophic differentiation was provoked the addition of indomethacin resulted in decreased hypertrophic marker expression. Interestingly, when mature chondrocytes were treated with indomethacin, a clear increase in collagen type 2 expression was observed. Similarly, when ATDC5 cells and bone marrow stem cells were pre-differentiated to obtain a chondrocyte phenotype and indomethacin was added from this time point onwards, low concentrations of indomethacin also resulted in increased chondrogenic differentiation.

Indomethacin induces differential effects on in vitro endochondral ossification, depending on the chondrocyte's differentiation stage, with complete inhibition of chondrogenic differentiation as the most pronounced action. This observation may provide a rationale behind the elusive mode of action of indomethacin in the treatment of heterotopic ossifications.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 129 - 129
1 Jul 2014
Oomen P Meijer K van der Westen R Gransier R Emans P van Rhijn L
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Summary

The quantification of T1Rho relaxation times is not related with internal loading. Improvements in modeling and imaging techniques might lead to better understanding of the pathomechanics of the knee.

Introduction

The onset and progression of knee osteoarthritis has been associated with an increased external knee adduction moment (EKAM). However, this external measure has no direct relationship with internal loading of the knee. For a better understanding of the pathomechanics of the knee musculoskeletal models could be used to relate external and internal knee loading. Consequently, high internal loading might cause cartilage degeneration in patients with OA. T1RhoMRI can detect changes in proteoglycan content and is therefore a non-invasive measure of cartilage degeneration in knee OA. The purpose of this study was to relate internal loading of the knee simulated by musculoskeletal models with cartilage health using T1rhoMRI.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 289 - 289
1 Jul 2014
Caron M Emans P Surtel D Cremers A van Rhijn L Welting T
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Summary

Indomethacin has differential effects on chondrogencic outcome depending on differentiation stage

Introduction

Heterotopic ossification (HO) is the abnormal formation of bone in soft tissues and is a frequent complication of hip replacement surgery. The standard treatment to prevent HO is administration of the NSAID indomethacin. HOs are described to develop via endochondral ossification. As it is currently unknown how indomethacin prevents HO, we aimed to define whether indomethacin might influence HO via impairing the chondrogenic phase of endochondral ossification.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 168 - 168
1 Jul 2014
Oosterwaal M Telfer S Woodburn J Witlox A Hermus J van Rhijn L Meijer K
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Summary Statement

An alternative way to assess three dimensional skin motion artefacts of kinematic models is presented and applied to a novel kinematic foot model. Largest skin motion is measured in the tarsal region.

Introduction

Motion capture systems are being used in daily clinical practise for gait analysis. Last decade several kinematic foot models have been presented to gain more insight in joint movement in various foot pathologies. No method is known to directly measure bone movement in a clinical setting. Current golden standard is based on measurement of motion of skin markers and translation to joint kinematics. Rigid body assumptions and skin motion artefacts can seriously influence the outcome of this approach and rigorous validation is required before clinical application is feasible. Validation of kinematic models is currently done via comparison with bone pin studies. However, these studies can only assess major bones in a highly invasive way; another problem is the non-synchronous measurement of skin markers and bone pins. Recently the Glasgow Maastricht kinematic foot model, which comprises all 26 foot segments, has been presented. To validate the model we propose a novel non-invasive method for the assessment of skin motion artefact, involving loaded CT data.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 305 - 305
1 Jul 2014
Roth A Bogie R Willems P Welting T Arts C van Rhijn L
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Summary Statement

Novel radiopaque UHMWPE sublaminar cables may be a promising alternative to gliding pedicle screws or titanium sublaminar cables within a growth-guidance system for the surgical treatment of early onset scoliosis.

Introduction

Growth-guidance or self-lengthening rod systems are an alternative to subcutaneous growing rods and the vertical expandable prosthetic titanium rib for the treatment of early onset scoliosis. Their main perceived advantage over growing rods is the marked decrease in subsequent operative procedures. The Shilla growth-guidance system and a modern Luque trolley are examples of such systems; both depend on gliding pedicle screws and/or sliding titanium sublaminar wires. However, the unknown consequences of metal-on-metal wear debris are reason for concern especially in young patients. In this study, instrumentation stability, residual growth in the operated segment after surgery and biocompatibility of the novel radiopaque UHMWPE cables as an alternative to gliding pedicles screws or titanium sublaminar wires were assessed in an immature sheep model.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 287 - 287
1 Sep 2012
Bogie R Voss L Welting T Willems P Arts J Van Rhijn L
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INTRODUCTION

Surgical correction of spinal deformities in the growing child can be applied with or without fusion. Sublaminar wiring, first described by Luque, allows continuation of growth of the non-fused spine after correction of the deformity. Neurological complications and wire breakage are the main clinical problems during the introduction and removal of currently used sublaminar wires. In this pilot study a posterior hybrid construction with the use of a medical-grade UHMWPE (Dyneema Purity®) sublaminar wire was assessed in an ovine model. We hypothesized that such a hybrid construction can safely replace current titanium laminar wires, while providing sufficient stability of the non-fused spinal column with preservation of growth.

MATERIALS AND METHODS

This study included 6 Tesselaar sheep, age 7±2months. Two pedicle screws (Legacy system, Medtronic) were placed at lumbar level. Four consecutive laminae were attached to two titanium bars (4.5 mm) using 3 mm diameter UHMWPE (Dyneema Purity®) on the left side and 5 mm diameter on the right side. The sublaminar wires were fixed with a double loop sliding knot and tightened with a tensioning device. As a control, in one animal titanium sublaminar wires (Atlas cable, Medtronic) were applied. After sacrifice the spine of the animals was harvested. Radiographs were taken and CT scans were performed. The vertebrae were dissected and placed in formaldehyde for macroscopic and histological evaluation.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXVII | Pages 31 - 31
1 Jun 2012
van Loon PM van Rhijn L
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Introduction

Spinal deformations are a deviation of the natural arrangement of forces during growth. Environmental factors play a part in these deviations. The presence of lordosis in the thoracic spine is a causative factor in spinal deformations that needs to be addressed. Most biomechanical models of bracing have a scientific background. Has older knowledge lost its value? In living structures, all processes such as regulation of equilibrium in posture and movement use Newton's law and extended laws of Hooke for conservation of energy, momentum, and angular momentum under control of the central nervous system. Form follows function (phylogenetic and ontogenetic) in the spine as primary engine in movement in animals. The change in function in bipedals is that the coupling mechanism at the thoracolumbar joint now couples a reversed pendulum.

Methods

A literature search shows a clear gap in the evolution in science on deformities during 1914–45. In 1792, Van Gesscher postulated two concepts in Observations on Deformations of the Spine (Dutch). First, the optimalisation of the balancing forces in men needs a specific optimum curvature to keep the weight of the head and shoulders above the hips. The second concept was the role of sitting in relation to changes around the discs at the thoracolumbar spine. Girls who read or knitted while sitting developed scoliosis more easily than did others. His extending (by lordosis) corrective corset was used for more than 150 years before plaster became popular. Andry described guidance and correction of growing spines with use of the moulding capability of muscular forces, with exercises and extending corsets (for so-called weak girls). Extension and avoidance of incorrect posture during sitting became a mainstay in orthopaedics (and schools). In 1907, Wullstein described experiments in young dogs to show how forced fiexion produces all characteristics of kyphotic deformities. In 1912, Murk Jansen did a critical review of all available knowledge and his own research in The Physiologic Scoliosis and its causes. Post mortem studies showed anatomical asymmetry in the left and right crura of the diaphragm, which indicated that asymmetric rotational forces in ventilation could induce predominant lateral curves. In-vivo tests show increased thoracolumbar kyphosis if siblings are put in seated positions too frequently and too soon. The stiffening in kyphosis creates a fulcrum to cantilever the opposing rotational forces to lateral curvatures. In experiments in rabbits, lower intrathoracic pressure was shown in the right pleural cavity. Common alertness of parents and teachers was underwritten. Some of this still survives. In progressed scoliosis, Sayre's method of corrective plastering in suspension and Calot's corrections in prone position under anaesthesia and plaster shelves with lordosis in bed became popular. In the Volkmann Hueter principle, the resilience of the deformable structures in the spine were identified–eg, the discs, the apophyses, and the cartilage in joints have a role in spinal deformity. Cobb drew attention to the clinical aspects of scoliosis. Roth provided a comprehensive explanation of how growth is organised and regulated by the oldest organ of animal life: the central nervous system in vertebrates. Between 1960 and 1985, Roth developed his concepts on neurovertebral and neuro-osseous growth relations and the tension-driven incongruence of growth. Roth provided new biological knowledge about how growth seems to support older clinical observations. In animal experiments, mechanical modelling, and radiological studies in scoliosis he stressed the role that growth has in the formation of the spine. A so-called short cord can indeed cause scoliosis. Recent studies with MRI in idiopathic scoliosis confirm this hypothesis. Personal observations In 2008, a study showed that forceful restoration of thoracolumbar lordosis can correct double major scoliotic curves. A consequent thoracolumbar kyphotic curve was found, and recently reproduced. The thoracolumbar lordotic intervention brace technique showed promising results. It relied on the older techniques, leaving only the fear for lordosis brought by Dickson. In personal observations, the presence of neuromuscular tightness or tension also present in progressive scoliosis as representatives of deforming and protective forces.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 166 - 166
1 May 2011
Arts J Hermus J Van De Berg F Guldemond N Van Rhijn L
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Introduction: Ponseti and Friedman suggest that curve type is genetically determined and that curve types do not change throughout its course. In current clinical practice scoliosis is seen as a more dynamic process. Therefore we like to postulate that the natural history of idiopathic scoliosis can change during growth when left untreated.

Aim of the Study: This study focused on the shift of curve patterns as result of age, especially in patients younger than ten years. It was assessed whether age is a factor in the dynamic progression of idiopathic scoliosis. We evaluated patients records as well as radiographic images and clinical measures.

Materials and Methods: 48 Patients with idiopathic scoliosis who visited the scoliosis team between 1990 and 2007 were included. The criteria for inclusion were a curve less than 30° and not treated with brace or operative procedures. Curve pattern changes were classified according to the Scoliosis Research Society classification and the Lenke classification.

Results: The forty-eight patient records demographics consisted of eleven males and thirty-seven females. Their mean age at the start of follow-up was 11,2 years (range 4–17). Mean follow-up lasted 3,4 years (range 1–11,2). Thirteen patients were diagnosed with juvenile idiopathic scoliosis and thirty-five patients were diagnosed with an adolescent idiopathic scoliosis. Eight from the forty-eight patients, showed curve pattern changes according the SRS classification: six females and two males. Six of the thirtteen patients with juvenile scoliosis showed a shift of the scoliosis curves (46%). Two of the thirty-five patients with the adolescent scoliosis showed a shift of the scoliosis curves (6%; p< 0,05).

In eleven patients with juvenile scoliosis(84,6%) there was a shift in the Lenke classification, while this only occurred in eighttteen patients with adolescent scoliosis(51,4%) (p< 0,05). No curve pattern changes occurred in two patients with juvenile idiopathic scoliosis(15,4%) and in twelve patients of the adolescent idiopathic scoliosis(34,3%) (p< 0,05).

Conclusion: There is evidence that idiopathic scoliosis has an genetic origin, but not all elements of the scoliosis formation can be explained. We found changes in curve patterns which suggest that idiopathic scoliosis is not a fixed deformity, but a dynamic process especially in patients younger than 10 years.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 148 - 148
1 Mar 2009
van Ooij A Kurtz S Van Rhijn L de Bruin T
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We removed 23 Charité artificial discs in 19 patients due to severe back-and legpain and performed an anterior as well posterior fusion. Mean interval between insertion and retrieval is 8,4 years (3,0–16,0 years). The mean age at retrieval is 49,4 years (40–72 years). The cause of persistent or recurrent pain was one or more of several problems thought to be related to the pain: subsidence, migration, wear with or without breakage of the metal marker ring, facetjoint or adjacent degeneration. In all cases wear of the polyethylene core was seen in major or minor degree. The wear was related to posterior impingement possibly due to hyperlordosis and extension instability and was subsequently more pronounced in the peripheral rim than in the central dome. Also a relationship was noted to in vivo oxidation of the polyethylene, especially in the rim. In the periprosthetic tissue an inflammatory reaction was found, more in the severe wear cases. Polyethylene loaded macrophages were seen, also polyethylene particles lying freely in the tissue. The macrophages proved positive for Interleukin 6. The wear pattern and the inflammatory reaction resembles the pattern seen in total hips and knees. Probably a substantial number of patients will exhibit these wear changes some years after insertion. It is questionable whether changes in sterilization and packaging and better insertion and sizing techniques will prevent wear development in the future.