Biomaterial Database

Force- and moment-generating capacity of lower-extremity muscles before and after tendon lengthening. 1992

S L Delp, and F E Zajac

Biomedical Engineering Department, Northwestern University, Evanston, Illinois.

A computer model of the human lower extremity was developed to study how surgical lengthening of tendon affects the force- and moment-generating capacity of the muscles. This model computes the maximum isometric force and the resulting joint moments that each muscle-tendon complex can develop at any body position. Tendon lengthenings were simulated by increasing the tendon length of each muscle-tendon complex and computing the change in the maximum isometric muscle force and joint moments at a specific body position. These simulations showed that the forces and moments developed by the ankle plantarflexors are extremely sensitive to changes in tendon length. For example, at a body position corresponding to the midstance phase of gait, the maximum isometric moment generated by soleus decreased 30% with a 1-cm increase in tendon length, and 85% with a 2-cm increase in tendon length. In contrast, 1- and 2-cm increases in iliopsoas tendon length decreased its hip flexion moment by only 4% and 9%, respectively. This article quantifies the sensitivity of muscle force and joint moments to changes in tendon length for the most commonly lengthened lower-extremity tendons. These results indicate how much each of these tendons should be lengthened to achieve an incremental decrease in muscle force or joint moment.

UI	MeSH Term	Description	Entries
D007537	Isometric Contraction	Muscular contractions characterized by increase in tension without change in length.	Contraction, Isometric,Contractions, Isometric,Isometric Contractions
D007719	Knee Joint	A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.	Superior Tibiofibular Joint,Joint, Knee,Joint, Superior Tibiofibular,Knee Joints,Superior Tibiofibular Joints,Tibiofibular Joint, Superior
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D003196	Computer Graphics	The process of pictorial communication, between human and computers, in which the computer input and output have the form of charts, drawings, or other appropriate pictorial representation.	Computer Graphic,Graphic, Computer,Graphics, Computer
D003198	Computer Simulation	Computer-based representation of physical systems and phenomena such as chemical processes.	Computational Modeling,Computational Modelling,Computer Models,In silico Modeling,In silico Models,In silico Simulation,Models, Computer,Computerized Models,Computer Model,Computer Simulations,Computerized Model,In silico Model,Model, Computer,Model, Computerized,Model, In silico,Modeling, Computational,Modeling, In silico,Modelling, Computational,Simulation, Computer,Simulation, In silico,Simulations, Computer
D006621	Hip Joint	The joint that is formed by the articulation of the head of FEMUR and the ACETABULUM of the PELVIS.	Acetabulofemoral Joint,Acetabulofemoral Joints,Hip Joints,Joint, Acetabulofemoral,Joint, Hip,Joints, Acetabulofemoral,Joints, Hip
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000843	Ankle Joint	The joint that is formed by the inferior articular and malleolar articular surfaces of the TIBIA; the malleolar articular surface of the FIBULA; and the medial malleolar, lateral malleolar, and superior surfaces of the TALUS.	Ankle Syndesmosis,Articulatio talocruralis,Distal Tibiofibular Joint,Inferior Tibiofibular Joint,Talocrural Joint,Tibiofibular Ankle Syndesmosis,Tibiofibular Syndesmosis,Ankle Joints,Ankle Syndesmoses,Ankle Syndesmosis, Tibiofibular,Distal Tibiofibular Joints,Inferior Tibiofibular Joints,Joint, Ankle,Joints, Ankle,Syndesmosis, Ankle,Talocrural Joints,Tibiofibular Ankle Syndesmoses,Tibiofibular Joint, Distal,Tibiofibular Syndesmoses