Abstract: A curved scissor linkage mechanism (1) includes at least four linkage elements (2) each having a first end (3) and a second end (4). The linkage elements are arranged to form sides of one or more rhombi or parallelograms. Each linkage element is rotationally connected to another linkage elements via a revolute joint (5) at the first end and is rotationally connected to another one of the other linkage elements via another revolute joint at the second end. The linkage elements are configured so that the axes of each joint coincide at one common remote centre of motion. The mechanism is connectable to a first external member (7) at a proximal end and is rotationally connectable to a second external member (9) at an opposite distal end to obtain three DOFs. The scissor linkage mechanism may further include a motion controlling mechanism.

Abstract: The invention relates to a method of determining the laxity of a joint (9, 15) of a human (5) or an animal. The method comprises providing at least one patient-specific geometrical model (1) of at least one bone and/or at least one prosthesis comprised by the joint. Known loads are applied to the joint or to a part of the body connected to the joint, and a series of actual images (16) of the joint are obtained while the loads are applied. Then the at least one patient-specific geometrical model (1) is registered onto the actual images (16). Based thereon relative displacement and/or rotation of the at least one bone and/or at least one prosthesis is calculated as a function of the applied loads, and based thereon a measure of the laxity of the joint is determined. The invention further relates to a system for performing such a method and to a computer readable medium for performing such a method.

Abstract: The invention relates to a curved spherical scissors linkage mechanism (1) comprising at least four linkage elements (2) each having a first end (3) and a second end (4); the linkage elements are arranged to form sides of one rhombus or parallelogram, or a series, such as a network, of joined rhombi or parallelograms. Each of the linkage elements is rotationally connected to one of the other linkage elements via a revolute joint (5) at or near the first end and is rotationally connected to another one of the other linkage elements via another revolute joint at or near the second end. The linkage elements are shaped, dimensioned and arranged so that the axes of all the revolute joints coincide at one common remote centre of motion (RCM). Furthermore, the mechanism is grounded or connected or connectable to a first external member (7) at a proximal end and is rotationally connected or connectable to a second external member (9) at an opposite distal end.

Abstract: A curved scissor linkage mechanism (1) includes at least four linkage elements (2) each having a first end (3) and a second end (4). The linkage elements are arranged to form sides of one or more rhombi or parallelograms. Each linkage element is rotationally connected to another linkage elements via a revolute joint (5) at the first end and is rotationally connected to another one of the other linkage elements via another revolute joint at the second end. The linkage elements are configured so that the axes of each joint coincide at one common remote centre of motion. The mechanism is connectable to a first external member (7) at a proximal end and is rotationally connectable to a second external member (9) at an opposite distal end to obtain three DOFs. The scissor linkage mechanism may further include a motion controlling mechanism.

Abstract: The invention relates to a method of determining the laxity of a joint (9, 15) of a human (5) or an animal. The method comprises providing at least one patient-specific geometrical model (1) of at least one bone and/or at least one prosthesis comprised by the joint. Known loads are applied to the joint or to a part of the body connected to the joint, and a series of actual images (16) of the joint are obtained while the loads are applied. Then the at least one patient-specific geometrical model (1) is registered onto the actual images (16). Based thereon relative displacement and/or rotation of the at least one bone and/or at least one prosthesis is calculated as a function of the applied loads, and based thereon a measure of the laxity of the joint is determined. The invention further relates to a system for performing such a method and to a computer readable medium for performing such a method.