Automatic determination of anatomical coordinate systems for three-dimensional bone models of the isolated human knee

Abstract

The combination of three-dimensional (3-D) models with dual fluoroscopy is increasingly popular for evaluating joint function in vivo. Applying these modalities to study knee motion with high accuracy requires reliable anatomical coordinate systems (ACSs) for the femur and tibia. Therefore, a robust method for creating ACSs from 3-D models of the femur and tibia is required. We present and evaluate an automated method for constructing ACSs for the distal femur and proximal tibia based solely on 3-D bone models. The algorithm requires no observer interactions and uses model cross-sectional area, center of mass, principal axes of inertia, and cylindrical surface fitting to construct the ACSs. The algorithm was applied to the femur and tibia of ten (unpaired) human cadaveric knees. Due to the automated nature of the algorithm, the within specimen variability is zero for a given bone model. The algorithm's repeatability was evaluated by calculating variability in ACS location and orientation across specimens. Differences in ACS location and orientation between specimens were low (<1.5mm and <2.5°). Variability arose primarily from natural anatomical and morphological differences between specimens. The presented algorithm provides an alternative method for automatically determining subject-specific ACSs from the distal femur and proximal tibia.

Variations in the three‐dimensional location and orientation of the ACL in healthy subjects relative to patients after transtibial ACL reconstruction

“…The medial-lateral (M-L) axis of the femur was defined by fitting a cylinder to the posterior aspect of the femoral condyles (Fig. 2) using a method described by Miranda et al 39 The axis of the cylinder extends from the most medial to the most lateral aspect of the posterior femoral condyles and the femoral coordinate system origin is Anatomic coordinate systems were created in the femur (left image) and tibia (right image). A cylinder was fit to the posterior femoral condyles to define the femoral medial-lateral axis and a plane was fit to the tibial plateau to define the tibial superior-inferior axis.…”

Long-axis rotation: a missing degree of freedom in avian bipedal locomotion

“…Alternatively, one might choose axes that most accurately depict the interaction among articular surfaces comprising a joint. To describe human knee kinematics, for example, the LAR axis is sometimes oriented normal to the tibial plateau (Miranda et al, 2010;Scanlan et al, 2012;Kaiser et al, 2013). This standard allows the femoral condyles to remain articulated during LAR.…”

“…Distally, polygons forming the two femoral condyles (not including the tibiofibular crest) were isolated and fitted with cylinders, following a method used in human biomechanics (e.g. Miranda et al, 2010). Each cylinder's centroid formed the origin of a distal ACS.…”

The 2014 ABJS Nicolas Andry Award: The Puzzle of the Thumb: Mobility, Stability, and Demands in Opposition

“…New methods incorporate historical information and contributions from our work using CT, MR, and live kinematic data of divergent geometric bone patterns, joint contact, and movement to predict contact pressures between general 3-D surfaces or to predict functional movement and wear. We are pursuing these with collaborations at Brown University and University of Auckland, including the potential use of high-resolution registration with dual fluoroscopy [73,104]. The computational methods employ either statistical shape modeling [5,41,66] or rigid body dynamics [41], integrating 3-D data to develop subject-specific models to predict changes over time, such as patterns of joint degeneration, response to fracture, or ligament disruption.…”