Applications of numerical methods in biomechanics
Makaleler > Tam Makale · 2011
Yazarlar: Mahmut PEKEDİS
Journal of Biomechanics, SCI Expanded İndekslerine Giren Dergi, Uluslararası, Wos, 2011, cilt 44, ss 15-15
DOI: 10.1016/j.jbiomech.2011.02.055
Özet
<p>Ankle injuries are the most encountered cases in sporting and physical activities. Approximately 15% of these injuries have affected the ankle joints and ligaments severely. Sometimes even if an appropriate treatment is applied, 10–30% of lateral ligaments transform into the chronic disease. The anterior drawer test (ADT) widely adopted in clinical treatment was used to determine the integrity of ligaments. However, when the ankle is in a different position, it is difficult to determine the stresses and strains developed in ligaments during the implementation of the test.</p><p>First, the ankle model (tibia, fibia, calcaneus, and talus) was developed with computer tomography, then the nonlinear finite element method was applied to analyze the stresses and strains occurred in ligaments and bones for four different positions (10° dorsiflexion, 0° neutral position, 10° plantar flexion, 20° plantar flexion). The ATFL, CFL, PTFL, ATT, TN, TC, PTT ligaments were modeled three dimensionally. Then these ligaments were attached to the relevant points according to the anatomical structure of foot. Non-linear finite element analysis module was selected due to the complex geometry and the contact conditions, and the model was solved iteratively. The analysis contained the effect of friction between the tibia and the talus. The material constants for ligaments and bones were taken from the literature. Initially, the stresses, strains and displacements were found for medial and lateral ligaments when 80N horizontal force was applied to the calcaneus for four different angles of foot. Then the forward displacements of foot were determined by applying the same load in case of intact and cut ligaments.</p><p>When the anterior displacement of foot is sorted from high to down in terms of different positions, it was found to be as 0°N>20°PF>10°>DF>10°PF, respectively, by applying 80 N force on calcaneus in horizontal direction. The maximum displacements were found on calcaneus where the loads were applied and the minimum displacements were found on fibula and tibia where the supports were located. The same stress values were determined for calcaneus and talus at 10°DF and 20°PF position and the minimum stresses for all bone were found at 10°PF position. The maximum anterior displacement was found on CFL while the minimum displacement was found on AFTL for all positions. The maximum von Mises stresses on the surface of talus were found at the highest angle (20° plantar flexion) and minimum von Mises stresses were found at the lowest angle (10° plantar flexion) position. When 80 N force is applied to the calcaneus for neutral position, maximum stresses were found on TCL, ATTL and CFL while the minimum stresses were found on AFTL and PTTL. The amount of forward displacement of foot was found to be 6.11 mm for 0° neutral position and in the case of all ligaments are intact. When CFL was cut, the ankle progressed 6.20 mm. As a result we could say that the CFL has prevented the ankle from moving forward as much as 0.9 mm.</p><p>The finite element method can be used as a powerful tool in the simulation of living structures. Using of noninvasive methods such as finite element method can help to determine behaviour of ankle and ligaments before the treatment (anterior drawer test) applied to the patients.</p>