Related Experiment Video
Updated: May 12, 2026
07:43
In Vivo Quantification of Hip Arthrokinematics during Dynamic Weight-bearing Activities using Dual Fluoroscopy
Published on: July 2, 2021
Cylindrical axis, not epicondyles, approximates perpendicular to knee axes.
Clifton W Hancock1, Mark J Winston, Joel M Bach
1Penn State Hershey Medical Center, Hershey, PA, USA. clifton.hancock@ucdenver.edu
Clinical Orthopaedics and Related Research
|March 29, 2013
Summary
The cylindrical axis (CA) more accurately represents the knee
Area of Science:
- Orthopedic biomechanics and surgical planning.
- Analysis of lower limb joint kinematics.
Background:
- The transepicondylar axis (TEA) is commonly used to represent the knee's flexion-extension axis.
- This is based on the assumption that both axes are perpendicular to the mechanical axis.
- The cylindrical axis (CA) is proposed as a more accurate representation of tibial motion.
Purpose of the Study:
- To compare the transepicondylar axis (TEA) and cylindrical axis (CA) relative to the mechanical axes.
- To determine which axis more consistently approximates orthogonality to the mechanical axis for surgical goals.
Main Methods:
- Three-dimensional models were created from CT scans of five cadaver limbs.
- Three observers measured the TEA, CA, and mechanical axes (femoral and tibial).
- Angles were calculated in 2-D and 3-D, and their magnitudes and variances were compared.
Main Results:
- The CA demonstrated angles closer to 90° relative to the mechanical axes than the TEA.
- In 2-D, CA angles were 92° (femur) and 93° (tibia) vs. TEA angles of 94° (femur) and 94° (tibia).
- In 3-D, CA angles were 88° (femur) and 88° (tibia) vs. TEA angles of 87° (femur) and 86° (tibia).
- The TEA showed higher variance compared to the CA in 2-D measurements.
Conclusions:
- The cylindrical axis (CA) forms more orthogonal angles to the femoral and tibial mechanical axes than the TEA.
- While differences are small, further research is needed to determine their clinical and biomechanical significance.
Related Concept Videos
01:16Bones of the Lower Limb: Femur and Patella
The femur is the body's longest and strongest bone spanning the thigh region. Its head articulates with the acetabulum of the hip bone to form the hip joint. A minor indentation on the medial side of the femoral head, called the fovea capitis, serves as the site of attachment for the ligament of the head of the femur. This weak ligament spans the femur and acetabulum and supports the hip joint. The narrowed region below the head is the neck of the femur. The inclination angle between the neck...
01:16Perpendicular-Axis Theorem
The perpendicular-axis theorem states that the moment of inertia of a planar object about an axis perpendicular to its plane is equal to the sum of the moments of inertia about two mutually perpendicular concurrent axes lying in the plane of the body.
Consider a circular disc of mass M and radius R lying along an x-y plane. The origin lies at the center of the disc, and the z-axis is perpendicular to the disc's plane. All three axes coincide at the disc's center. The moment of inertia of this...
Consider a circular disc of mass M and radius R lying along an x-y plane. The origin lies at the center of the disc, and the z-axis is perpendicular to the disc's plane. All three axes coincide at the disc's center. The moment of inertia of this...
01:23Muscles that Move the Leg
The movement of the legs is facilitated by numerous muscles located within the anterior, medial, and posterior compartments of the thigh.
Anterior Compartment
The quadriceps femoris, the most visible muscle of the anterior compartment, is integral for leg extension and thigh flexion. It is formed by merging four distinct muscles — the vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris. The quadriceps tendon, a shared tendon of the four quadriceps muscles, is affixed to...
Anterior Compartment
The quadriceps femoris, the most visible muscle of the anterior compartment, is integral for leg extension and thigh flexion. It is formed by merging four distinct muscles — the vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris. The quadriceps tendon, a shared tendon of the four quadriceps muscles, is affixed to...
01:23Knee Joint
The knee joint is the most complicated joint in the body. It consists of three articulations– two tibiofemoral and one patellofemoral. As is characteristic of synovial joints, the knee joint has a thin articular capsule that partially surrounds this joint cavity. Additionally, several ligaments, muscles, and cartilaginous structures support the movement of the knee.
A total of seven ligaments support the knee joint. The patellar ligament, which is also attached to the quadriceps femoris group...
A total of seven ligaments support the knee joint. The patellar ligament, which is also attached to the quadriceps femoris group...
01:15Bones of the Upper Limb: Ulna
The ulna and radius are parallel bones of the antebrachium or the forearm. The ulna lies medially and consists of a bony tip called the olecranon process at its proximal end. This hook-like projection articulates with the olecranon fossa of the humerus and forms the "hinged" ulnohumeral part of the elbow joint. This joint facilitates forearm extension and flexion while preventing its hyperextension. Similarly, the coronoid process, another bony projection on the proximal/anterior side of the...
01:09Bones of the Upper Limb: Radius
The radius is longer of the two bones that make up the human antebrachium or forearm. At the proximal end, the radius articulates with the capitulum of the humerus and the radial notch of the ulna to form the elbow joint. At the distal end, the radius articulates with the ulna via the ulnar notch, forming the distal radioulnar joint. Distally, the radius also attaches to the carpal wrist bones (scaphoid and lunate) to form the radiocarpal joint.
The radius has a nail-shaped head, and a short...
The radius has a nail-shaped head, and a short...