Orthopaedic Biology Laboratories
Yale Orthopaedic Biology Laboratories have extensive expertise in the molecular and cellular aspects of bone biology.
Among special services offered are the following:
- Molecular and cellular bone biology
- Histologic analyses of musculoskeletal tissues
- Preclinical animal studies
Among special services offered are the following:
The Orthopaedic Biomechanics Laboratory, located on the fifth floor of the Farnam Memorial Building, assesses the biomechanical properties of musculoskeletal tissues by providing services and technical assistance in a variety of biomechanical testing techniques. The Lab works with investigators to design optimal animal models and testing methods for each project. Mechanical testing of bone, soft tissue, and orthopaedic implant and prosthetic devices as well as in vivo loading of small animals is possible. Design and fabrication of loading fixtures are offered. All methods of testing are customized for the user’s need. Available methods using 2 biomechanical testing systems (Instron 8874 and Instron 5542) include:
i) 3- and 4-point bending of whole bone and machined bone samples: The bending tests measure the mechanical behavior of materials in simple beam loading. Specimens are supported as a simple beam, with the compressive load applied at midpoint. Load-deflection curves are analyzed for stiffness (the slope of the initial portion of the curve), strength (maximum load), post-yield deflection, and work-to-failure. Modulus of elasticity and flexural stress can be calculated by accounting for specimen geometry. These tests primarily focus on the systematic evaluation of phenotypic changes in mouse bones, with a focus on long-bone diaphyses and cortical bone.
ii) Static compression, tension, or torsion of whole bones and machined samples: The structural components of the musculoskeletal system are loaded in tension, compression, bending, shear, torsion, or a combination of these modes. The failure mode and fracture mechanics of whole bones is determined by axial (both compression and tension) or torsion testing. By accounting for geometry (i.e., machining samples to consistent dimensions), we can determine tissue specific properties.
iii) Tensile testing of tendons, ligaments, and entheses: These musculoskeletal structures are loaded in tension, compression, bending, shear, torsion, or a combination of these modes. The failure mode and fracture mechanics of whole bones is determined by axial (both compression and tension) or torsion testing. Accounting for geometry (i.e., machining samples to consistent dimensions), we determine material properties.
iv) Dynamic loading (fatigue) of bone, tendons, ligaments, and entheses: In contrast to static loads, dynamic loads are repetitive or cyclic. Cyclic loads on a structure can lead to fatigue damage and ultimately failure or, in the case of bone, stress fracture. By applying cyclic loads, we can determine the fatigue behavior of bone, tendons, ligaments and insertion sites.
v) In vivo loading of musculoskeletal tissue in small animals: Small animal models that enable the application of specific loads to individual bones and tendons have been developed. These are useful in determining the biological response to changes in mechanical strains engendered by load-bearing.
vi) Mechanical testing of orthopaedic implants and devices: Many joint replacement products, most commonly for hip, spine and knee, are marketed. As articulating joints represent the most complex mechanical systems in the body, implant designers have many challenges to overcome. The mechanical testing systems housed by the Core have the capacity for basic static testing of raw materials, impact loading of joint components, and evaluation of fatigue and wear properties of numerous implants and devices.
vii) Finite element model validation: Finite Element (FE) models can be used to non-destructively evaluate stresses and strains generated within bone or at interfaces between bone and orthopaedic components. The accuracy of an FE model will depend on how well the geometric shape of the model and the material properties represent the physical case. To assure accuracy of the model, we validate it by performing a set of well-defined experiments, comparing the mechanical behavior of the physical bone to the model.
Quality Assurance: Both Instron systems, including all load cells, both actuators and the hydraulic pump, are cleaned and calibrated yearly by Instron (Norwood, MA) technicians. Calibration and verification ensure the systems satisfy materials testing ISO and ASTM standards. Validation studies are conducted prior to each new loading configuration to ensure proper design and anticipated results.
For more information, contact email@example.com (Phone: (203) 737-7037)
This laboratory provides histological preparations of both soft and hard tissues including undemineralized bone. Processing of bone requires specialized plastic embedding techniques utilizing either methylmethacrylate or glycolmethacrylate methods which are done on site. A wide array of special stains for bone tissues are performed on a routine basis. The laboratory is a fully equipped histology facility utilizing state of the art tissue processors, specialized microtomes, cryostats and knives designed to section hard tissues. High resolution digital photography of microscope slides is available.
- Plastic embedding of undemineralized bone
- Special stains
- Routine histology/cryotomy
- Digital photography