Ex Vivo Evaluation of Cementless Acetabular Cup Stability Using Impact Analyses with a Hammer Instrumented with Strain Sensors

International audienceThe acetabular cup (AC) implant stability is determinant for the success of cementless hip arthroplasty. A method based on the analysis of the impact force applied during the press-fit insertion of the AC implant using a hammer instrumented with a force sensor was developed to assess the AC implant stability. The aim of the present study was to investigate the performance of a method using a hammer equipped with strain sensors to retrieve the AC implant stability. Different AC implants were inserted in five bovine samples with different stability conditions leading to 57 configurations. The AC implant was impacted 16 times by the two hammers consecutively. For each impact; an indicator I S (respectively I F) determined by analyzing the time variation of the signal corresponding to the averaged strain (respectively force) obtained with the stress (respectively strain) hammer was calculated. The pull-out force F was measured for each configuration. F was significantly correlated with I S (R 2 = 0.79) and I F (R 2 = 0.80). The present method has the advantage of not modifying the shape of the hammer that can be sterilized easily. This study opens new paths towards the development of a decision support system to assess the AC implant stability

Dependence of the primary stability of cementless acetabular cup implants on their biomechanical environment

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Feasibility and safety of treating non-unions in tibia, femur and humerus with autologous, expanded, bone marrow-derived mesenchymal stromal cells associated with biphasic calcium phosphate biomaterials in a multicentric, non-comparative trial

Background: ORTHO-1 is a European, multicentric, first in human clinical trial to prove safety and feasibility after surgical implantation of commercially available biphasic calcium phosphate bioceramic granules associated during surgery with autologous mesenchymal stromal cells expanded from bone marrow (BM-hMSC) under good manufacturing practices, in patients with long bone pseudarthrosis. Methods: Twenty-eight patients with femur, tibia or humerus diaphyseal or metaphyso-diaphyseal non-unions were recruited and surgically treated in France, Germany, Italy and Spain with 100 or 200 million BM-hMSC/mL associated with 5–10 cc of bioceramic granules. Patients were followed up during one year. The investigational advanced therapy medicinal product (ATMP) was expanded under the same protocol in all four countries, and approved by each National Competent Authority. Findings: With safety as primary end-point, no severe adverse event was reported as related to the BM-hMSC. With feasibility as secondary end-point, the participating production centres manufactured the BM-hMSC as planned. The ATMP combined to the bioceramic was surgically delivered to the non-unions, and 26/28 treated patients were found radiologically healed at one year (3 out of 4 cortices with bone bridging). Interpretation: Safety and feasibility were clinically proven for surgical implantation of expanded autologous BM-hMSC with bioceramic. Funding: EU-FP7-HEALTH-2009, REBORNE Project (GA: 241876).The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/FP7-HEALTH-2009); REBORNE Project (GA: 241876

Fixation of the Cemented Stem: Clinical Relevance of the Porosity and Thickness of the Cement Mantle

The aim of this review paper is to define the fixation of the cemented stem. Polymethyl methacrylate, otherwise known as “bone cement”, has been used in the fixation of hip implants since the early 1960s. Sir John Charnley, the pioneer of modern hip replacement, incorporated the use of cement in the development of low frictional torque hip arthroplasty. In this paper, the concepts of femoral stem design and fixation, clinical results, and advances in understanding of the optimal use of cement are reviewed. The purpose of this paper is to help understanding and discussions on the thickness and the porosity of the cement mantle in total hip arthroplasty. Cement does not act as an adhesive, as sometimes thought, but relies on an interlocking fit to provide mechanical stability at the cement–bone interface, while at the prosthesis– cement interface it achieves stability by optimizing the fit of the implant in the cement mantle, such as in a tapered femoral stem

A Multicentric, Open-Label, Randomized, Comparative Clinical Trial of Two Different Doses of Expanded hBM-MSCs Plus Biomaterial versus Iliac Crest Autograft, for Bone Healing in Nonunions after Long Bone Fractures: Study Protocol

ORTHOUNION is a multicentre, open, comparative, three-arm, randomized clinical trial (EudraCT number 2015-000431-32) to compare the efficacy, at one and two years, of autologous human bone marrow-derived expanded mesenchymal stromal cell (hBM-MSC) treatments versus iliac crest autograft (ICA) to enhance bone healing in patients with diaphyseal and/or metaphysodiaphyseal fracture (femur, tibia, and humerus) status of atrophic or oligotrophic nonunion (more than 9 months after the acute fracture, including recalcitrant cases after failed treatments). The primary objective is to determine if the treatment with hBM-MSCs combined with biomaterial is superior to ICA in obtaining bone healing. If confirmed, a secondary objective is set to determine if the dose of 100 × 106 hBM-MSCs is noninferior to that of 200 × 106 hBM-MSCs. The participants (n = 108) will be randomly assigned to either the experimental low dose (n = 36), the experimental high dose (n = 36), or the comparator arm (n = 36) using a central randomization service. The trial will be conducted in 20 clinical centres in Spain, France, Germany, and Italy under the same clinical protocol. The confirmation of superiority for the proposed ATMP in nonunions may foster the future of bone regenerative medicine in this indication. On the contrary, absence of superiority may underline its limitations in clinical use

Cell therapy and tissue engineering in spinal degeneration and orthopaedics.

La dégénérescence discale lombaire (DDL) est caractérisée par un vieillissement prématuré du disque intervertébral (DIV) et une déshydratation progressive du nucleus pulposus (NP) entrainant in fine des lombalgies. L'objectif général de ce travail est d'établir des données précliniques afin de régénérer le DIV en cas de DDL modérée. Dans un premier chapitre, nous avons déterminé une association de facteur de croissance et un mode de culture visant à obtenir une prédifférentiation nucléopulpogénique de cellules stromales mésenchymateuses (CSMs) humaines issues de la moelle osseuse. Nos résultats montrent que la culture tridimensionnelle des CSMs en billes d'alginate en présence de TGF-β3, GDF-5 et BMP-7 les oriente vers un phénotype cartilagineux. Dans un deuxième chapitre, nous avons élaboré un modèle porcin de DDL induite par cryolésion et nous l'avons comparé aux techniques de référence. L'évaluation de l'importance de la DDL a été effectuée par scanner, IRM et histologiquement. Un score histologique de DDL porcine a été décrit et validé. La cryolésion a permis d'obtenir une DDL plus importante que les autres techniques. Dans un troisième chapitre, nous avons injecté les CSMs préorientées dans les DIV lésés. L'analyse IRM a montré une amélioration de l'intensité du signal et de la surface du NP après injection des cellules. L'analyse immunohistologique a montré une survie des CSMs dans les DIV porcins à 2 mois. Dans un quatrième chapitre, nous avons comparé les taux de fusion et de complication pour la RhBMP-2 et la greffe spongieuse autologue dans les arthrodèses lombaires par voie antérieure dans une même cohorte de patients. La RhBMP-2 était associée à un taux de fusion inférieur et un taux de complications radiologiques supérieur à l'autogreffe spongieuse.Degenerative disc disease (DDD) is characterized by premature aging of the intervertebral disc (IVD) and gradual dehydration of the nucleus pulposus (NP), ultimately causing back pain. The general objective of this work is to establish preclinical data to regenerate the IVD in moderate DDD. In the first chapter, we have identified a growth factor association and a culture method to achieve nucleopulpogenic prédifférentiation of mesenchymal stromal cells (MSCs) derived from human bone marrow. Our results show that the three-dimensional culture of MSCs in alginate beads in the presence of TGF-β3, GDF-5 and BMP-7 directs them to a cartilaginous phenotype. In the second chapter, we developed a porcine model of DDD, induced by cryoinjury, and compared it to reference techniques. Assessing the importance of DDD was performed by CT, MRI and histologically. A histological score of porcine DDD has been described and validated. Cryoinjury yielded a higher DDD that other techniques. In a third chapter, we injected preoriented MSCs in cryo-injured IVDs. MRI analysis showed an improvement in the signal intensity and the surface of the NP after the injection. The immunohistological analysis showed a survival of the MSCs in the porcine IVD 2 months after injection. In a fourth chapter, we compared the rate of fusion and complication for rhBMP-2 and autologous cancellous graft in the anterior lumbar interbody fusion, in the same cohort of patients. RhBMP-2 was associated with a lower fusion rate and a higher rate of radiological complications than the cancellous autograft

Speed of sound measurement in porcine intervertebral discs: an in vitro study

Disc degeneration is associated with premature ageing of intervertebral discs (IVD) and a gradual degradation of the nucleus pulposus (NP) biomechanical properties. The objective of this study is to investigate whether quantitative ultrasound (QUS) technique can be used to determine the speed of sound (SOS) in the NP and to correlate SOS with histological measurements. The ultrasonic measurements are realized with a 3.5MHz focused monoelement transducer used in echographic mode. The value of the interspecimen variability of SOS is significantly superior than the reproducibility of the measurements, which indicates that the technique is sensitive to variations of the material properties of the NP. A significant correlation between SOS values and the percentage of physaliphorous cells ratios is obtained (R-2 = 0: 68) when considering all samples. QUS can be useful to assess the biomechanical properties of the IVD, which may be useful in the context of tissue engineering applications