Trabecular Architecture of the Proximal Tibia in Extant Hominids

Area of Science:

• Paleoanthropology
• Biomechanics
• Skeletal Biology

Background:

• Locomotion and posture vary significantly across extant hominoids, leading to distinct joint loading patterns.
• Trabecular bone structure is sensitive to mechanical loading and joint posture, adapting to functional demands.
• Previous research focused on the femur; this study uniquely examines the proximal tibia's trabecular architecture.

Purpose of the Study:

• To investigate how differences in joint use and habitual posture are reflected in the proximal tibial morphology of extant hominoids.
• To establish a comparative framework for interpreting locomotor behaviors and biomechanical loading in fossil hominids.

Main Methods:

• High-resolution microtomography was used to scan proximal tibiae from Homo sapiens, Gorilla, Pan troglodytes, and Pongo sp.
• Canonical holistic morphometric analysis quantified trabecular bone volume fraction and degree of anisotropy.
• Principal component analysis and MANOVA assessed spatial distributions and group differences in trabecular structure.

Main Results:

• Trabecular bone volume and anisotropy in the proximal tibia correlate with habitual knee posture (extended in humans, flexed in apes).
• Male gorillas showed more extended knee use than females, with no significant sex differences in Homo or Pan.
• Tibial morphology provides a record of locomotor loading patterns.

Conclusions:

• Proximal tibial trabecular structure is indicative of habitual locomotor loading in extant hominids.
• These findings provide a basis for inferring knee posture and locomotion in fossil hominids.
• The study highlights the link between biomechanical loading, joint posture, and skeletal morphology.