Variation of the Three-Dimensional Femoral J-Curve in the Native Knee

Abstract

The native femoral J-Curve is known to be a relevant determinant of knee biomechanics. Similarly, after total knee arthroplasty, the J-Curve of the femoral implant component is reported to have a high impact on knee kinematics. The shape of the native femoral J-Curve has previously been analyzed in 2D, however, the knee motion is not planar. In this study, we investigated the J-Curve in 3D by principal component analysis (PCA) and the resulting mean shapes and modes by geometric parameter analysis. Surface models of 90 cadaveric femora were available, 56 male, 32 female and two without respective information. After the translation to a bone-specific coordinate system, relevant contours of the femoral condyles were derived using virtual rotating cutting planes. For each derived contour, an extremum search was performed. The extremum points were used to define the 3D J-Curve of each condyle. Afterwards a PCA and a geometric parameter analysis were performed on the medial and lateral 3D J-Curves. The normalized measures of the mean shapes and the aspects of shape variation of the male and female 3D J-Curves were found to be similar. When considering both female and male J-Curves in a combined analysis, the first mode of the PCA primarily consisted of changes in size, highlighting size differences between female and male femora. Apart from changes in size, variation regarding aspect ratio, arc lengths, orientation, circularity, as well as regarding relative location of the 3D J-Curves was found. The results of this study are in agreement with those of previous 2D analyses on shape and shape variation of the femoral J-Curves. The presented 3D analysis highlights new aspects of shape variability, e.g., regarding curvature and relative location in the transversal plane. Finally, the analysis presented may support the design of (patient-specific) femoral implant components for TKA.

The Role of Stability and Alignment in Improving Patient Outcomes After Total Knee Arthroplasty

“…While the anterior radius is larger on the lateral condyle, both posterior radii are similar, and the condyles increase in asymmetry from extension to flexion 74 . The condyles also change in shape, in addition to size, as they transition from the anterior trochlea to the posterior femur 74 . This unique geometry of the femoral J-curve plays an important role in determining the medial collateral ligament isometry and the lateral femoral condylar rollback around this medial pivot point.…”

“…The J-curve is defined by 2 radii—the anterior radius and the posterior radius—that are connected with a transitional zone 73 . While the anterior radius is larger on the lateral condyle, both posterior radii are similar, and the condyles increase in asymmetry from extension to flexion 74 . The condyles also change in shape, in addition to size, as they transition from the anterior trochlea to the posterior femur 74 .…”

“…This unique geometry of the femoral J-curve plays an important role in determining the medial collateral ligament isometry and the lateral femoral condylar rollback around this medial pivot point. However, current off-the-shelf implants only take into account the distal femoral offset, are symmetric in their design, and have J-curves that vary in size but not in shape 74 .…”

Improved Deep Convolutional Neural Network to Classify Osteoarthritis from Anterior Cruciate Ligament Tear Using Magnetic Resonance Imaging

“…The knee is the strongest joint in the human body. It is secured by ligament structures protect the knee joint's bone elements [1,2]. Every year, there are about 25,000 people with ACL ruptures [3].…”

Taking the Next Step in Personalised Orthopaedic Implantation

“…The use of patient-specific implants in primary endoprosthetics follows a comparable principle. Due to the optimal alignment and size as well as the shape of the implants, the physiological load transfer should be maintained in the entire movement of the joints [ 15 , 16 , 17 , 18 ].…”