Quantifying Joint Congruence With an Elastic Foundation

Abstract

The level of congruence between the articulating surfaces of a diarthrodial joint can vary substantially between individuals. Quantifying joint congruence using the most widespread metric, the ‘congruence index’, is not straightforward: the areas of the segmented bone that constitute the articular surfaces require accurate identification, their shape must be carefully described with appropriate functions, and the relative orientation of the surfaces measured precisely. In this work, we propose a new method of measuring joint congruence, which does not require these steps. First, a Finite Element (FE) simulation of an elastic layer compressed between each set of segmented bones is performed. These are then interpreted using the elastic foundation model, enabling an equivalent, but simpler, contact geometry to be identified. From this, the equivalent radius (quantification of joint congruence) is found. This defines the radius of a sphere contacting plane (or ‘ball on flat’) that produces an equivalent contact to that in each joint. The minimal joint space width (in this joint position) can also be estimated from the FE simulations. The new method has been applied to 10 healthy instances of the thumb metacarpophalangeal (MCP) joint. The ten thumb MCPs had similar levels and variability of congruence as the other diarthrodial joints that have been characterised previously. This new methodology enables efficient quantification of joint congruence and minimal joint space width directly from CT or MRI derived bone geometry in any relative orientation. It lends itself to large data sets and coupling with kinematic models.

Anatomy and mobility in the adult cadaveric craniocervical junction

“…This is in line with our results in Table 3, which all pointed towards a collinearity of range of motion and neutral zone, and an antagonistic role of hysteresis and coupled movements (also found in Figures 6 and 7). Regarding joint congruence, an increase in local antero‐posterior distances and decrease in medial distances between consecutive facets, considered here as a decrease in congruence (Burson‐Thomas et al, 2022), was associated with an increase in hysteresis and coupled movements. Hence, a poor joint congruence meant greater instability, which seems to make perfect sense from a mechanical perspective, as suggested by the ‘ball‐and‐socket’ joint model (Ernstbrunner et al, 2016).…”

Covariance in human limb joint articular morphology

“…Joint congruence refers to how closely two articulations reciprocally fit with one another (Ateshian, Rosenwasser, & Mow, 1992; Conconi & Parenti‐Castelli, 2014). A variety of methods have been proposed for quantifying joint congruence (Ateshian et al, 1992; Burson‐Thomas, Dickinson, & Browne, 2022; Conconi, Leardini, & Parenti‐Castelli, 2015; Conconi & Parenti‐Castelli, 2014; Connolly, Ronsky, Westover, Küpper, & Frayne, 2009), but at present there is little agreement on the best method for assessing this attribute. In general, three aspects of the joint must be carefully considered when quantifying congruence: articular shape and surface curvature must be accurately described, both of which are considered in tandem with an accurate reconstruction of the in vivo orientation of the joint (Connolly et al, 2009; Halilaj, Laidlaw, Moore, & Crisco, 2014).…”

To fix or not to fix!? Strategies and tools to place and fixate a flexible joint implant

“…Therefore, the results of the cadaver trail indicate the necessity of optimizing the design of the C-shape tip tweezers, specifically the integrated retraction mechanism. Functionality assessments of final concept A prototype of the final design was manufactured and tested by inserting the APRICOT® implant within a 3D-printed model of the thumb MCP joint [76].…”

“…Feasible fixation locations were determined and illustrated in Figure 6.2. The illustration is based on the anatomy of the thumb MCP joint (Figure 2.1 in Chapter 2), the surgical procedure, and the 3D model of the proximal phalanx [76]. Based on the 3D model, the flanges of the implant only cover the cartilage region on the proximal phalanx but do not reach the bone of the proximal phalanx.…”

“…The test rig shown in Figure 6.7 has been designed and built to simulate extensionflexion cycles of the MCP joint of the thumb with a 45±5°range of motion (ROM). The thumb proximal phalanx and metacarpal bones were 3D printed from the models [76]. Two elastic bands were added and fixed at the insertion points of the ulnar and radial collateral ligaments that were indicated on the bone models by the surgeon.…”