This study developed subject-specific, three-dimensional dynamic hindfoot models (1 in vivo, 1 in vitro) using 3D stress MRI data. Each model’s ability to capture mechanical phenomena including those of the healthy hindfoot and the hindfoot with ligament injury was evaluated through subject-specific experimental mechanical analyses (using an arthrometer and a stress MRI technique).
Existing software (3DVIEWNIXTM) was incorporated with software developed in-house (marching cubes program) to obtain the subject’s bone surface geometry, collateral and subtalar ligament insertion data. The bone surface data were then imported into a reverse engineering software package (Geomagic StudioTM) to obtain CAD representations for the bone geometries.
The ligaments’ non-linear structural properties were obtained directly from an existing experimental study or were estimated. Contact forces between bones were modeled using cartilage’s Elastic Modulus and an exponential term to imitate its nonlinear compression characteristics. The ADAMS 2003TM dynamic simulation software generated and solved the dynamic equations of motion under the forcing functions and boundary conditions.
The in vivo experimental kinematic data were smaller than those predicted by the model. This indicates that surrounding soft tissues excluding the ligaments may decrease joint range of motion. The in vitro model captured the experimental kinematic patterns of the ankle joint complex, but did so by under-estimating ankle joint motion and overestimating subtalar joint motion. Better knowledge of the ankle joint and subtalar joint ligament structural properties is necessary.
Similar to experimental data, the in vivo and in vitro models’ ankle joint complex had non-linear load-displacement properties in all directions. They are dependent on the contact of the articulating surfaces and ligament constraints. Sensitivity analyses indicated that kinematic changes caused by altering ligament geometry are smaller than changes caused by lateral ligament removal; therefore the model may be sensitive to predicting the changes that occur during ligament rupture.
The models’ assumptions and limitations include differences between the experimental and modeled boundary conditions, exclusion of the cartilage geometry, estimation of the contact damping coefficient, the contact stiffness and penetration exponent, estimation of the subtalar ligaments’ structural properties, generalized nonlinear properties for the collateral ligaments, and soft-tissue motion during the experiments. Future work must focus on developing a larger group of patient-specific models so that the output data has sufficient statistical power.
|2000||Funk JR, Hall GW, Crandall JR, Pilkey WD. Linear and quasi-linear viscoelastic characterization of ankle ligaments. J Biomech Eng. February 2000;122(1):15-22.|
|1989||Lundberg A, Svensson OK, Bylund C, Goldie I, Selvik G. Kinematics of the ankle/foot complex, II: pronation and supination. Foot Ankle Int. April 1989;9(5):248-253.|
|1983||Grood ES, Suntay WJ. A joint coordinate system for the clinical description of three-dimensional motions: application to the knee. J Biomech Eng. May 1983;105(2):136-144.|
|1987||Lorensen WE, Cline HE. Marching cubes: a high resolution 3D surface construction algorithm. Comput Graph. 1987;21(4):163-169.|
|1980||Woo SL-Y, Simon BR, Kuei SC, Akeson WH. Quasi-linear viscoelastic properties of normal articular cartilage. J Biomech Eng. May 1980;102(2):85-90.|
|2001||Chen W-P, Tang F-T, Ju C-W. Stress distribution of the foot during mid-stance to push-off in barefoot gait: a 3-D finite element analysis. Clin Biomech (Bristol, Avon). August 2001;16(7):614-620.|
|1999||Beillas P, Lavaste F, Nicolopoulos D, Kayventash K, Yang KH, Robin S. Foot and ankle finite element modeling using CT-scan data. In: Proceedings of the 43rd Stapp Car Crash Conference. October 25-27, 1999; San Diego, CA. Warrendale, PA: Society of Automotive Engineers:171-184. SAE 99SC11.|
|2001||Bandak FA, Tannous RE, Toridis T. On the development of an osseo-ligamentous finite element model of the human ankle joint. Int J Solids Struct. March 2001;38(10-13):1681-1697.|
|2000||Ledoux W, Camacho D, Ching R, Sangeorzan B. The development and validation of a computational foot and ankle model. Proceedings of the 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society; July 23-28, 2000.2899-2902.|
|1999||Bedewi PG, Digges KH. Investigating ankle injury mechanisms in offset frontal collisions utilizing computer modeling and case-study data. In: Proceedings of the 43rd Stapp Car Crash Conference. October 25-27, 1999; San Diego, CA. Warrendale, PA: Society of Automotive Engineers:217-242. SAE 99SC14.|
|1992||Schneck CD, Mesgarzadeh M, Bonakdarpour A, Ross GJ. MR imaging of the most commonly injured ankle ligaments, I: normal anatomy. Radiology. August 1992;184(2):499-506.|
|1993||Fung YC. Biomechanics: Mechanical Properties of Living Tissues. 2nd ed. New York, NY: Springer-Verlag; 1993.|
|1993||Scott SH, Winter DA. Biomechanical model of the human foot: kinematics and kinetics during the stance phase of walking. J Biomech. 1993;26(9):1091-1104.|
|1985||Stormont DM, Morrey BF, An K-N, Cass JR. Stability of the loaded ankle: relation between articular restraint and primary and secondary static restraints. Am J Sports Med. 1985;13(5):295-300.|
|2002||Wu G, Siegler S, Allard P, Kirtley C, Leardini A, Rosenbaum D, Whittle M, D'Lima DD, Cristofolini L, Witte H, Schmid O, Stokes I. ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion, I: ankle, hip, and spine. J Biomech. 2002;35(4):543-548.|
|1983||Rasmussen O, Kromann-Andersen C, Boe S. Deltoid ligament: functional analysis of the medial collateral ligamentous apparatus of the ankle joint. Acta Orthop Scand. 1983;54(1):36-44.|
|1985||Rasmussen O. Stability of the ankle joint: analysis of the function and traumatology of the ankle ligaments. Acta Orthop Scand. 1985;56(suppl 211):1-75.|
|1997||Beaugonin M, Haug E, Cesari D. Improvement of numerical ankle/foot model: modeling of deformable bone. In: Proceedings of the 41st Stapp Car Crash Conference. November 13-14, 1997; Lake Buena Vista, FL. Warrendale, PA: Society of Automotive Engineers:225-237. SAE 973331.|
|1995||Beaugonin M, Haug E, Munck G, Cesari D. A preliminary numerical model of the human ankle under impact loading. International Conference on Pelvic and Lower Extremity Injuries Proceedings; 1995.277-289.|
|1990||Nigg BM, Skarvan G, Frank CB, Yeadon MR. Elongation and forces of ankle ligaments in a physiological range of motion. Foot Ankle. August 1990;11(1):30-40.|
|1989||Lundberg A, Svensson OK, Bylund C, Selvik G. Kinematics of the ankle/foot complex, III: influence of leg rotation. Foot Ankle Int. June 1989;9(6):304-309.|
|2002||Salathe EP, Arangio GA. A biomechanical model of the foot: the role of muscles, tendons, and ligaments. J Biomech Eng. 2002;124(3):281-287.|
|1988||Siegler S, Block J, Schenck CD. The mechanical characteristics of the collateral ligaments of the human ankle joint. Foot Ankle. April 1988;8(5):234-242.|
|1989||Lundberg A, Goldie I, Kalin B, Selvik G. Kinematics of the ankle/foot complex: plantarflexion and dorsiflexion. Foot Ankle Int. February 1989;9(4):194-200.|
|2002||Camacho DLA, Ledoux WR, Rohr ES, Sangeorzan BJ, Ching RP. A three-dimensional, anatomically detailed foot model: a foundation for a finite element simulation and means of quantifying foot-bone position. J Rehab Res Dev. 2002;39(3):401-410.|
|2012||Shin J, Yue N, Untaroiu CD. A finite element model of the foot and ankle for automotive impact applications. Annals Biomed Eng. December 2012;40(12):2519-2531.|
|2011||Shin J. Injury and Response of Human Ankle and Subtalar Joints Under Complex Loading [PhD thesis]. Charlottesville, VA: University of Virginia; December 2011.|