A two-dimensional wrist model for carpal instability and force transmission
Sinan Seber1, Hande Gökdemir2, Abdurrahman Özçelik1, İzge Günal3, Ruhi Aydın2, Nusret Köse1
1Department of Orthopedics, Eskişehir Osmangazi University Hospital, Eskişehir, Turkey
2Department of Civil Enginering, Eskişehir Osmangazi University, Eskişehir, Turkey
3Department of Orthopedics, Dokuz Eylül University Hospital, İzmir, Turkey
Keywords: Carpal ligaments, force transmission, instability, wrist, finite element model.
Abstract
Objective: Distribution of internal forces among the carpal bones and ligaments, and contribution of the supporting ligaments to the integrity of the wrist was investigated.
Patients and methods: Wrist radiograph of a healthy volunteer was used to develop the model. The SAP 2000 computer program was used to model the bones, cartilage and ligaments. Initially, a total of 143 Newton of compression load was applied from the metacarpals and internal force distribution across the wrist joint was recorded. Then, internal forces on the ligaments were measured after a total of 143 N of tension load was applied along the longitudinal axes of the metacarpals. The intact and ligaments-sectioned wrists were concomitantly evaluated.
Results: 81% of the loads were dissipated through the radius. Lunotriquetral ligament was loaded in tension with the highest values in the intact wrist. After removing of the ligaments from the system alone or as pairs, the internal force was distributed among the ligaments in various patterns.
Discussion: To our knowledge, this is the first study to analyze the internal force distribution along the carpal ligaments. Findings of the present study may contribute to the better understanding of the biomechanical pathoanatomy of carpal instability.