A new technique to measure micromotion distribution around a cementless femoral stem

Self Cite

a b s t r a c tThe initial stability of cementless femoral components is crucial for the long-term success of total hip arthroplasty. This has been reported in animal and clinical studies. Until now, the stability was evaluated by the measurement of relative micromotion on a few simultaneous locations around the stem in cadaveric experiments. This paper presents an extended experimental setup to measure simultaneously local micromotion, subsidence and gap on hundreds of points at the bone-stem interface. This technique we applied to anatomical and straight stems in three pairs of cadaveric femurs. Measurements were in agreement with typically reported values. Conversely to other methods, which measure micromotion between implant and bone anchoring points of the measuring device, our method provides local micromotion between stem surface and adjacent bone surface. The observed variation of micromotion at the peri-implant surface confirms the importance of this simultaneous measure on a lot of points around the implant.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simultaneous and multisite measure of micromotion, subsidence and gap to evaluate femoral stem stability

Gortchacow

Wettstein

Pioletti

et al. 2012

Self Cite

“…Moreover, models are typically only verified for specific metrics, for example surface bone strains, and there will still be uncertainty associated with other metrics such as the underlying cancellous bone strains. Emerging experimental techniques may allow for greater levels of verification for micromotion (Gortchacow et al, 2011) and cancellous bone strains in the future (Gillard et al, 2013). There are major challenges to verify and validate predictions of probabilistic studies as there is the need to ensure that the models capture the distribution as well as the mean response.…”

Section: Validation and Verificationmentioning

confidence: 99%

Four decades of finite element analysis of orthopaedic devices: Where are we now and what are the opportunities?

Taylor

Prendergast

2015

146

106

a b s t r a c tFinite element has been used for more than four decades to study and evaluate the mechanical behaviour total joint replacements. In Huiskes seminal paper "Failed innovation in total hip replacement: diagnosis and proposals for a cure", finite element modelling was one of the potential cures to avoid poorly performing designs reaching the market place. The size and sophistication of models has increased significantly since that paper and a range of techniques are available from predicting the initial mechanical environment through to advanced adaptive simulations including bone adaptation, tissue differentiation, damage accumulation and wear. However, are we any closer to FE becoming an effective screening tool for new devices? This review contains a critical analysis of currently available finite element modelling techniques including (i) development of the basic model, the application of appropriate material properties, loading and boundary conditions, (ii) describing the initial mechanical environment of the bone-implant system, (iii) capturing the time dependent behaviour in adaptive simulations, (iv) the design and implementation of computer based experiments and (v) determining suitable performance metrics.The development of the underlying tools and techniques appears to have plateaued and further advances appear to be limited either by a lack of data to populate the models or the need to better understand the fundamentals of the mechanical and biological processes. There has been progress in the design of computer based experiments. Historically, FE has been used in a similar way to in vitro tests, by running only a limited set of analyses, typically of a single bone segment or joint under idealised conditions. The power of finite element is the ability to run multiple simulations and explore the performance of a device under a variety of conditions. There has been increasing usage of design of experiments, probabilistic techniques and more recently population based modelling to account for patient and surgical variability. In order to have effective screening methods, we need to continue to develop these approaches to examine the behaviour and performance of total joint replacements and benchmark them for devices with known clinical performance.Finite element will increasingly be used in the design, development and pre-clinical testing of total joint replacements. However, simulations must include holistic, closely corroborated, multi-domain analyses which account for real world variability.

“…More recently, micromotion measurement techniques based on micro-computed tomography (micro-CT) imaging were introduced, and demonstrated great potential. Notwithstanding the very high number of measurement points they can collect, they were limited to measurement around non-metallic implants due to imaging artifacts (Sukjamsri et al, 2015) or confined to a small portion of the implant (Gortchacow et al, 2012(Gortchacow et al, , 2011.…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, we extend a micromotion measurement technique based on radiopaque markers and micro-CT imaging (Gortchacow et al, 2011) to measure three dimensional micromotion at the entire bone-implant interface of a cementless femoral stem implanted in a cadaveric femur. The method will allow to measure micromotion for axial compression and torsion.…”

Section: Introductionmentioning

confidence: 99%

Full-field measurement of micromotion around a cementless femoral stem using micro-CT imaging and radiopaque markers

Camine

Rüdiger

Pioletti

et al. 2016

a b s t r a c tA good primary stability of cementless femoral stems is essential for the long-term success of total hip arthroplasty. Experimental measurement of implant micromotion with linear variable differential transformers is commonly used to assess implant primary stability in pre-clinical testing. But these measurements are often limited to a few distinct points at the interface. New techniques based on microcomputed tomography (micro-CT) have recently been introduced, such as Digital Volume Correlation (DVC) or markers-based approaches. DVC is however limited to measurement around non-metallic implants due to metal-induced imaging artifacts, and markers-based techniques are confined to a small portion of the implant. In this paper, we present a technique based on micro-CT imaging and radiopaque markers to provide the first full-field micromotion measurement at the entire bone-implant interface of a cementless femoral stem implanted in a cadaveric femur. Micromotion was measured during compression and torsion. Over 300 simultaneous measurement points were obtained. Micromotion amplitude ranged from 0 to 24 mm in compression and from 0 to 49 mm in torsion. Peak micromotion was distal in compression and proximal in torsion. The technique bias was 5.1 mm and its repeatability standard deviation was 4 mm. The method was thus highly reliable and compared well with results obtained with linear variable differential transformers (LVDTs) reported in the literature. These results indicate that this micro-CT based technique is perfectly relevant to observe local variations in primary stability around metallic implants. Possible applications include pre-clinical testing of implants and validation of patient-specific models for pre-operative planning.