Patella Quadriceps Connectors - Connectors¶
Connector elements are used to apply external loading to the quadriceps tendon. In the absence of experimental data, the points manually placed in the MR images to define the quadriceps tendon are used to define the line of action of the quadriceps load (see Ligaments and Tendons and Quadriceps Tendon Anatomy for more information on point placement). One node on the connector element is tied to the femur’s fixed coordinate system to allow it to move with the femur.
Nodes¶
Two nodes are defined from the points that were manually defined from the MR image during mesh creation (Mesh creation - Ligaments and Tendons). There should be a total of four points defined in the MR image that correspond to the quadriceps tendon insertion in to the patella (medial and lateral margins), and two points that are more proximal along the tendon (medial and lateral). These points are used to define the spring representation of the quadriceps.
- \(P_1\): the medial margin of the quadriceps tendon insertion into the patella
- \(P_2\): the lateral margin of the quadriceps tendon insertion into the patella
- \(P_3\): the medial margin of the quadriceps tendon proximal to the patella
- \(P_4\): the lateral margin of the quadriceps tendon proximal to the patella
These points are used to calculate two more points that lie between \(P_1\), \(P_2\) and \(P_3\), \(P_4\).
A unit vector is defined that is parallel to the line that intersects \(P_5\) and \(P_6\),
and a point is defined proximal to \(P_6\) along the line of action,
- Node 1: \(P_6\), the point proximal to the patella, at the midpoint between the points defined in the MR image \(P_3\) and \(P_4\)
- Node 2: \(P_7\), the point that is prixmal to \(P_6\) along the line of of action defined with \(P_5\) and \(P_6\).
Elements¶
One connector element is defined with nodes 1 and 2.
Ties¶
- Node 1 is rigidly tied to the most proximal nodes in the quadricps mesh
- Node 2 is rigidly tied to the origin of the femur’s fixed coordinate system