The BioRobotics & Mechanical Testing Core (BRMTC) provides biomechanical testing of biological structures and biomaterials.
Our world-class facilities allow investigators to conduct high-quality research of the mechanical properties of existing biological structures and constructs, as well as to quantify the potential for new technologies and clinical advancements.
The BMRTC provides testing capabilities for a wide range of biomechanical modalities and will offer expert advice and support for development of new test protocols, as well as innovative techniques for instrumentation and data collection. Modalities include tissues, joints, and multi-articular units, such as foot or spine segments.
The BioRobotics Core offers facilities and expertise for mechanical testing of musculoskeletal structures and biomaterials through an organizational structure of shared equipment and resources. The Core provides expertise in material testing using devices currently located in the Lerner Research Institute as well as several simVITRO® based robotic testing systems.
In addition, we will assist in data management for user experiments including, data collection, data analysis, and data archiving. The Core supports testing of tissues, joints and multi-articular units, such as foot or spine segments. Suitable applications include testing of ligaments, tendons, bone, cartilage, implants, orthotics, limbs, etc.
Let Cleveland Clinic provide state-of-the-art robotic orthopaedic biomechanical testing to answer your clinical questions. With over 15 years of experience in this field, the BioRobotics Cab can provide simVITRO testing services using simVITRO software and one of our several robotic musculoskeletal simulators. These simulators range in load capacity from 5N for rat and mouse joint testing all the way up to 3000N loads for human lower extremity joint testing. Customizable setups for knee, spine, hip, shoulder, foot/ankle, elbow and hand/wrist testing. Learn more about simVITRO’s capabilities.
These services can be used to provide insight into; tissue engineering, medical devices, surgical techniques, disease pathologies, orthopedics, and fracture healing and treatment. Structural and material properties of tissues and synthetic materials can be acquired through uniaxial and biaxial biomechanical testing. Use one of our uniaxial and biaxial testing systems to help answer your clinical research questions.
Biomechanical phenotyping of transgenic models allows for quantification and comparison of functional changes in connective tissues (bone, tendon, skin).
Full System Development:
We can apply our unique expertise in this field to your project or laboratory. We can assist in replication of our existing simVITRO® systems, or developing new and custom systems that are unique solutions to your challenges.
Our team’s expertise in systems engineering, mechanical design, and data acquisition, allows us to develop new integrated hardware when off-the-shelf solutions aren’t available. Our close proximity to other MDS resources (FEA, Machining, Electronics, and Design) allows us to provide turn-key solutions based on our systems engineering approach. These solutions range from simple fixture design to complex robotic hardware. The rotary stage depicted is an additional robotic axis developed to give our system a greater range of motion.
Our team’s extensive experience in developing our simVITRO® Universal Musculoskeletal Simulators can be applied to your automated test equipment needs. In addition, we can develop software to assist you with automated data post processing and analysis. These skills include Matlab as well as extensive training and certifications in LabVIEW.
simVITRO® testing requires both the tools and the knowledge for robotic orthopaedic biomechanical testing. Let our team provide remote or onsite training for simVITRO software as well as joint testing methodologies.
Come visit our lab or stop by our booth at an upcoming scientific meeting such as ORS, ASB, ISB, WCB, ISTA, NASS or AAOS. We look forward to meeting you!
Role of the Native Fiber Bundles of the Anterior Cruciate Ligament in Knee Joint Kinematics
Client: Joe Carney, MD / US Navy
Services Provided: Experiment Design / Robotic Knee Joint Testing / Data Analysis / Manuscript Preparation
Anatomical descriptions of the anterior cruciate ligament (ACL) typically describe two distinct fiber bundles, the anterior-medial bundle (AMB) and the posterior-lateral bundle (PLB). This has inspired the development of double-bundle (DB), four-tunnel, reconstruction techniques for ACL ruptures. There are, however, no clinical studies yet that show an advantage of one technique over the other. Recent biomechanical studies have shown that the DB technique has the potential to reduce knee joint laxity, but it is not yet clear to what extent this is desirable or replicates the function of the native ACL bundles. The aim of this study was to determine the role of the native AMB and PLB via robotic testing in a cadaver model with and without weightbearing. Our results show that the AMB has a larger effect on anterior tibia translation than the PLB. Both bundles, however, appear to contribute equally to rotational stability at 15 degrees flexion or more. The PLB tended to have a larger contribution to rotational stability but only at full extension. It is premature to interpret these results with respect to the debate on single vs. double bundle reconstruction, but our results suggest that a single bundle reconstruction, placed at the AMB insertions, may be sufficient to restore translational stability. It should be kept in mind that these results were obtained without compressive load on the joint. Preliminary results suggest the ACL bundles have less influence on passive knee joint motion when Lachman and pivot shift tests are performed during simulated weightbearing.
The Effect of Medial Opening Wedge High Tibial Osteotomy on Medial Collateral Ligament Tension
Client: Steve Fening, PhD, and Lutul Farrow, MD / Cleveland Clinic
Services Provided: Experiment Design / Robotic Knee Joint Testing / Manuscript Preparation
Medial opening wedge high tibial osteotomy (HTO) as utilized for varus gonarthrosis shifts the lower extremity weight-bearing axis towards the intact lateral compartment. Agneskirchner et al. recently demonstrated that medial compartment pressures actually increased following medial opening wedge HTO. They hypothesized that this was due to increased medial collateral ligament (MCL) tension, but this was not actually measured. Our first hypothesis is that MCL strain increases following HTO. Our second hypothesis is that MCL strain will decrease following partial MCL release. The objective of this study is to determine how medial opening wedge HTO effects MCL tension. Differential variable reluctance transducer strain gauges were placed at the mid-substance of the superficial and posterior oblique portions of the MCL. Each knee was tested using a 6-degree of freedom robotic simulator. We tested 4 conditions: intact knee, 1 cm opening wedge HTO, partial MCL release, and complete MCL release. The clinical exam variable consisted of a simulated Lachman’s exam and varus-valgus stress testing. Simulated gait consisted of a 1000 N of compressive force combined with variable varus torques from 0 to 40 N-M. Each test was performed at 0 and 30 degrees of flexion. The principal findings of our study demonstrate that superficial MCL tension does not change significantly but tension in the posterior oblique portions of the MCL do change significantly following medial opening wedge HTO. Our findings suggest that the increased medial compartment contact pressures seen following HTO may be the result of increased posterior oblique tension alone. Furthermore, partial release of the superficial MCL and posterior oblique portion did not significantly affect ligament tension.
Knee: Patellofemoral Study
Client: Jason Halloran, PhD, and Jack Andrish, MD / Cleveland Clinic
Services Provided: Experiment Design / Robotic Knee Joint Testing / Data Analysis
Patellofemoral complications, including femoral trochlear dysplasia, are the single largest reason for knee related clinical visits. Trochlear dysplasia is a morphological abnormality that can lead to patellar instability and dislocation. Trochlear osteotomy, literally raising the anterior surface of the lateral condyle, is considered a viable intervention procedure for symptomatic knees. Development of a presurgical planning tool able to address this issue, as well as many others, will lead to fewer complications and improved patient satisfaction. Such a framework requires predictive capabilities found through systematic validation and correlation with clinical outcomes. Towards the goal of development and validation of such a platform, the objective of this study was to compare specimen-specific explicit finite element (FE) predicted contact mechanics with experimental results before and after trochlear osteotomy. Novelty is included as previous patellofemoral studies, experimental or computational, have not quantified the effects surgical intervention on resulting contact mechanics. An explicit framework was chosen to evaluate robustness and potential computational efficiency.
Knee: Multiscale Modeling
Client: Ahmet Erdemir, PhD / Cleveland Clinic
Services Provided: Experiment Design / Uniaxial Material Testing / Robotic Knee Joint Testing / Data Analysis
Cells of the musculoskeletal system are known to have a biological response to deformation. Deformations, when abnormal in magnitude, duration, and/or frequency content, can lead to cell damage and possible disruption in homeostasis of the extracellular matrix. These mechanisms can be studied in an isolated fashion but connecting mechanical cellular response to organ level mechanics and human movement requires a multiscale approach. The goal of this research program is to portray that prediction of cell deformations from loads acting on the human body, therefore a clear depiction of the mechanical pathway, is possible, if a multiscale simulation approach is used. Multiresolution models of the knee joint, representative of joint, tissue and cell structure and mechanics, were developed for this purpose. Comprehensive mechanical testing at joint, tissue and cell levels were conducted for parameter estimation and validation, including in vitro loading of the knee joint representative of lifelike loading scenarios. The research team will utilize this platform to establish the relationship between the structural and loading state of the knee and chondrocyte stresses to explore potential mechanisms of cartilage degeneration.
Hip Stability and Range of Motion: Soft Tissue Role in Total Hip Arthroplasty Versus Femoral Head Resurfacing
Client: Wael Barsoum, MD / Cleveland Clinic
Services Provided: Experiment Design / Robotic Hip Joint Testing / Data Analysis / Manuscript Preparation
Total hip arthroplasty (THA) is a widely successful operation for relieving pain and restoring function. Dislocation is a devastating complication after THA, with a reported incidence as high as 10% following primary surgeries. Femoral head resurfacing (FHR) is an increasingly popular option typically used in a younger population because of its theoretical increased stability and bone preservation of the femur. Dislocation rates have been reported as low as 0.75%. However, much controversy surrounds the resurgence of FHR and its biomechanical implications of retaining the femoral neck, leading to small head-to-neck ratio (HNR) and large jump distance relative to THA. We have developed a dynamic cadaveric robotic model which functions in real time under load-control parameters to recreate in vivo hip mechanics. The objectives of this study were to (1) examine the biomechanical differences between each construct of the native hip, FHR, and THA, and (2) evaluate the role of the soft tissue on the stability and dislocation potential of each construct.
Bone Strain Measurement During Simulation of Lower Extremity Musculoskeletal Biomechanics
Client: Peter Cavanagh, PhD, DSc, and Brian Davis PhD / Cleveland Clinic and NASA
Services Provided: Experiment Design / Robotic Foot Joint Testing / Data Analysis / Manuscript Preparation
Orthopedic research that investigates the in vitro forces applied to bones, tendons and ligaments during simulated exercise has been difficult to achieve due to limitations of applying full-physiological loading to the joint under investigation in a real-time manner. The Universal Musculoskeletal Simulator (UMS) allows researchers to simulate exercise on cadaver joints by using motorized actuators to simulate muscle forces and simultaneously contact the joint with an external load. This study simulated walking at one-fourth speed and varying BW percentages (16.5%, 38.4%, 66.7%, and 100% BW). Bone strain measurements were recorded for correlation with the extrinsic muscle forces and external forces during the exercise. View publication on PubMed.
Assessment of the Effects of Diabetes on Midfoot Joint Pressures
Client: Brian Davis, PhD / Cleveland Clinic
Services provided: Experiment Design / Robotic Foot Joint Testing / Data Analysis / Manuscript Preparation
One of the more serious diabetic complications is Charcot neuroarthropathy (CN), a disease that results in arch collapse and permanent foot deformity. However, very little is known about the etiology of CN. From a mechanical standpoint, it is likely that there is a “vicious circle” in terms of (i) arch collapse causing increased midfoot joint pressures, and (ii) increased joint contact pressures exacerbating the collapse of midfoot bones. This study focused on assessment of peak joint pressure difference between diabetic and non-diabetic cadaver feet during simulated walking. We hypothesized that joint pressures are higher for diabetics than normal population.
Materials and Methods: Sixteen cadaver foot specimens (eight control and eight diabetic specimens) were used in this study. Human gait at 25% of typical walking speed (averaged stance duration of 3.2s) was simulated by a custom-designed Universal Musculoskeletal Simulator. Four medial midfoot joint pressures (the first metatarsocuneiform, the medial naviculocuneiform, the middle naviculocuneiform, and the first intercuneiform) were measured dynamically during full stance.
Results: The pressures in each of the four measured midfoot joints were significantly greater in the diabetic feet (p = 0.015, p = 0.025, p < 0.001, and p = 0.545, respectively). Conclusion: Across all four tested joints, the diabetic cadaver specimens had, on average, 46% higher peak pressures than the control cadaver feet during the simulated stance phase.
Clinical Relevance: This finding suggests that diabetic patients could be predisposed to arch collapse even before there are visible signs of bone or joint abnormalities.
View publication on PubMed.
Effect of Humeral Head Defect Size on Glenohumeral Stability: A Cadaveric Study of Simulated Hill-Sachs Defects
Client: Scott Kaar, MD, and Steve Fening, PhD / Cleveland Clinic
Services Provided: Experiment Design / Robotic Shoulder Joint Testing / Data Analysis / Manuscript Preparation
Hill-Sachs lesions are often present with recurrent shoulder instability and may be a cause of failed Bankart repair. The goal of this study was to determine how large of a lesion is required to reduce stability. Humeral head defects, 1/8, 3/8, 5/8, and 7/8 of the humeral head radius, were created in 8 human cadaveric shoulders, simulating Hill-Sachs defects. Testing positions included 45 degrees and 90 degrees of abduction and 40 degrees of internal rotation, neutral, and 40 degrees of external rotation. Testing occurred at each defect size sequentially from smallest to largest for all abduction and rotation combinations. The humeral head was translated at 0.5 mm/s 45 degrees anteroinferiorly to the horizontal glenoid axis until dislocation. Distance to dislocation, defined as humeral head translation until it began to subluxate, was the primary outcome measure. The study found that glenohumeral stability decreases at a 5/8 radius defect in external rotation and abduction. At 7/8 radius, there was a further decrease in stability at neutral and external rotation. View publication on PubMed.
Biomechanical Analysis of a Unique Interspinous Fixation Device Intended for Minimally Invasive Spinal Fusion
Client: Lars Gilbertson, PhD / Cleveland Clinic and Bill Marras, PhD / The Ohio State University
Services Provided: Experiment Design / Robotic Spine Joint Testing / Data Analysis / Manuscript Preparation
Stabilization has proven to increase the fusion rates in the lumbar spine. Surgeons are continuously trying to achieve the goals of spine surgery using less invasive techniques. A new minimally invasive device has been approved to fixate two adjacent interspinous (IS) processes while the fusion occurs between the 2 vertebrae. The purpose of performing this study is to biomechanically compare different fixation systems for the stability supplementation in a Transforaminal Lumbar Interbody Fusions (TLIF). Cadaveric specimens from T12 to the sacrum were mounted to the robot. A stability comparison, through measuring the amount of motion between the instrumented vertebral segments, was done among the following scenarios: 1) intact spine, 2) TLIF, 3) TLIF with IS Fixation Device (ISD), 4) TLIF with ISD and unilateral pedicle screws, 5) TLIF with bilateral pedicle screws. The robot applied pure moment ±6Nm cycles in flexion-extension (FE), lateral bending (LB) and axial rotation (AR). The relative vertebral motion was captured using an optoelectronic camera system. The study showed that the ISD in conjunction with unilateral pedicle-screw fixation was statistically comparable to the stand alone bilateral pedicle-screw fixation in all planes of motion, flexion-extension, lateral bending and axial rotation.
The Kinetic and Kinematic Effect of Varying the Instantaneous Axis of Rotation of the Cervical Spine
Client: Robert McLain, MD / Cleveland Clinic
Services Provided: Experiment Design, Robotic Spine Joint Testing, Data Analysis, Manuscript Preparation
When considering movements of the cervical spine, the global (cervical spine as a whole) instantaneous axis of rotation (IAR) as well as the IAR for each adjacent set of vertebral bodies will vary depending on the particular activity being executed. For example, two ways to flex the neck include a chin tuck, or a long reach to look down over something. In each case the global IAR will vary along with the associated kinetics and kinematics of the spine. The effect on multi-level kinematics, along with any associated increase in shear loads, were measured when comparing global IAR placed at either the C3-C4 level, or the C6-C7 level.
Surface Contaminants Inhibit Osseointegration in a Novel Murine Model
Client: Edward Greenfeld, PhD / Case Western Reserve University
Services Provided: Experiment Design / Uniaxial Material Testing / Data Analysis / Manuscript Preparation
Surface contaminants, such as bacterial debris and manufacturing residues, may remain on orthopaedic implants after sterilization procedures and affect osseointegration. The goals of this study were to develop a model of osseointegration in order to determine whether removing surface contaminants enhances osseointegration. To develop the model, titanium alloy was implanted and osseointegration was measured over a five week time course. Histology, backscatter scanning electron microscopy and x-ray energy dispersive spectroscopy showed areas of bone in intimate physical contact with the implant, confirming osseointegration. Histomorphometric quantification of bone-to-implant contact and peri-implant bone and biomechanical pullout quantification of ultimate force, stiffness and work to failure increased significantly over time, also demonstrating successful osseointegration. We also found that a rigorous cleaning procedure significantly enhances bone-to-implant contact and biomechanical pullout measures by two-fold compared with implants that were autoclaved, as recommended by the manufacturer. The most likely interpretation of these results is that surface contaminants inhibit osseointegration. The results of this study justify the need for the development of better detection and removal techniques for contaminants on orthopaedic implants and other medical devices. View publication on Pubmed.
Biomechanical Phenotyping with 3 Point Bending: ADAMTS molecules, fibrillin-1 networks and cell regulation
Client: Suneel Apte, MBBS, DPhil / Cleveland Clinic
Services Provided: Uniaxial Material Testing
Several ADAMTS family members, e.g., ADAMTS10, ADAMTS17, ADAMTSL4, and ADAMTSL2, are mutated in disorders associated with fibrillin-1, a critical component of an extracellular network that regulates TGF-beta. These human and animal mutations have highlighted the potential role of ADAMTS proteins in fibrillin-rich tissues such as the zonule of the eye, and in regulating skeletal growth and skin/organ fibrosis. The project utilized a three point bending method to assist the research program in understanding the contributions to overall bone strength.
Peritoneum Material Properties
Client: Cleveland Clinic
Services Provided: Experiment Design / Uniaxial Material Testing / Data Analysis
More and more implantable medical devices are including allografts or other tissue based technologies. For some of these tissues it is important to understand what affect the storage environment, prior to implantation, will have on the mechanical properties of the tissue. In this experiment, properties such as stiffness, elasticity, and failure strength were measured for bovine peritoneum as a function of storage time, and storage medium.
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