Activity Indicator Facets

This chapter covers activity indicator facets, which are extra facets, facet extensions, or fossae near joints that have been associated with habitual activities. Many activity indicator facets are used to determine postural behaviors, such as kneeling and squatting. Load-carrying behaviors have also been assumed to result in accessory facets, especially at the sacro-iliac joint. Activity indicator facets, such as the Poirier’s facets, Allen’s facets, and Baastrup’s kissing spines, have become less frequently used by bioarchaeologists in recent years. Now, activity indicator facets are mainly found in archaeological site descriptions in which the activities are reconstructed using the site’s artifacts too. The waning interest in activity indicator facets may be due to the lack of clinical, sports, and animal research to support the link between the facets and activities.

Forces and Moments on the Knee During Kneeling and Squatting

Euler angle decomposition and inverse dynamics were used to determine the knee angles and net forces and moments applied to the tibia during kneeling and squatting with and without kneepads for 10 subjects in four postures: squatting (Squat), kneeling on the right knee (One Knee), bilateral kneeling near full flexion (Near Full) and bilateral kneeling near 90° flexion (Near 90). Kneepads affected the knee flexion (p= .002), medial forces (p= .035), and internal rotation moments (p= .006). Squat created loading conditions that had higher varus (p< .001) and resultant moments (p= .027) than kneeling. One Knee resulted in the highest force magnitudes and net moments (p< .001) of the kneeling postures. Thigh-calf and heel-gluteus contact forces decreased the flexion moment on average by 48% during Squat and Near Full.