Orthopaedic Biomechanics Research Laboratory

The Orthopaedic Biomechanics Research Lab is equipped with state-of-the-art equipment to examine the mechanical strength of musculoskeletal systems and implants, investigate the failure mechanism of bone-implant constructs, and study patients’ motion characteristics. The lab is also furnished with a powerful computer and sophisticated software for computer simulation and analysis of complex bone-implant constructs. Our computer generates patient-specific 3D geometric models based on CT/MRI images, performs virtual orthopedic surgery based on the patient's computer model, analyzes the construct strength and evaluates the potential for long-term implant survival. We make use of the finite element method to model and examine the mechanics of soft and hard tissues such as a knee/hip joint. We have developed techniques to build subject-specific finite element models directly from medical image data such as CT, and MRI images. Our techniques also digitize and characterize the material of bone and soft tissues to provide an assessment used in measuring clinical outcomes. Most of our work deals with experimental validation using cadaveric specimens and identification of clinical advantages using sensory and imaging feedback. We also use the Optotrak Certus 3D motion-capture system along with infrared light-emitting markers to track and record the positions and motions of the cadaveric models and to quantify the kinetics and kinematics of the skeletal system.

Uniaxial tension and compression load frames are utilized to determine material properties such as yield strength, ultimate tensile strength, Young’s modulus, Stress-Strain graph, etc.

The biomechanics Research Laboratory has two load frames, MTS 30/G and Instron machine. We conduct tension, compression, 3- and 4-point ben test, pullout test using multiple load cell capacities ranging from 10kN to 150kN.

Our software was recently updated to improve force and displacement resolution in our experiments. We have multiple fixtures, grips, compression plates, and bespoke holders which can be switched to suit sample dimensions and stress state.

Here at the biomechanics research group, load frames are used to apply load or displacement in a controlled fashion and to test human tissue.

The Optotrak Certus, NDI (Northern Digital Inc.) tracks kinetic motion of a body in real-time. The system uses active optical technology to measure the position and orientation of markers or sensors that are fixed on a movable body. When the body moves, the marker also moves proportionally. For a body with “n” number of parts, we use “n” number of markers to track motion individually.

The marker acts as a reference physical point for the imaginary points that will be marked throughout that specific part of the whole body. With this we will be able to get a rough contour of the desired parts initial and final state.

The system can capture 1000 frames per second. For each frame data is collected in respect to the cartesian coordinates in X, Y & Z axis. The system has the freedom to mark the origin anywhere in space within the machines range or take up the default origin.

Dr. INVIVO 4D2 (Rokit Healthcare Inc.) is a Bio-3Dprinter for effective, on-demand bio fabrication of human tissue models and implants. It is capable of printing freeform cell suspensions, hydrogels, thermoplastic filaments, pastes, and other composite materials, enabling both hard and soft tissue engineering.

Printing material capabilities: Collagen, Hyaluronic acid, Gelatin, Chitosan, Pluronic acid, Bio PLA, Bio PCL etc.

Pressure mapping sensor measures the pressure/force distribution of a specific area under an applied force.

The pressure sensor contains a matrix array of dielectric sensing elements which each unit is known as a “sensel”. When the sensel is loaded, the resistance of the semi conductive ink changes; this change is measured by the system. The output resistances are automatically converted to force or contact pressure values depending on the calibration factor.

Tekscan sensor model 4000 has two sensing areas that work independently. For each side, the sensing matrix is made up of 26 rows and 22 columns, making a total of 572 sensels that cover an area of 922.57mm2.

With the use of pressure sensors, we are able to visualize loading maps, detect peak force/stress values and determine contact area between bones.

Cycling Joint Loading machine

This rig has a modular design and can be implemented for cycling experiments. The main outcome of this rig is to provide cyclic loads to a bigger specimen such as a Knee joint, Lumbar spine etc.

The rig is made of Aluminum extrusions for its main body which can be modified extensively depending upon the nature of the experiment. The driving force is generated by a Servo motor which is connected to a National Instruments (NI) Data acquisition Device (DAQ) system and driven by a custom LabView code.

Shoulder load simulator

This rig is used to apply loads and simulate a shoulder joint. It uses simple flat aluminum extrusions and an array of pulleys which guide the weights connected to the muscles and bones of a shoulder to simulate its movement.