Table 1. Material properties assigned to FE model of the ostrich tarsometatarsus, and yield and ultimate values for comparison with FEA results.

E = Young’s modulus (stress/strain), G = shear modulus, ᴠ = Poisson’s ratio, σ_yield and σ_ult = yield and ultimate stresses, ε_ult and ε_ult = yield and ultimate strains, ε_ult* = strain up to which cancellous bone retains some load-carrying ability. Moduli are in GigaPascals (GPa), and σ_yield and σ_ult in MegaPascals (MPa). Yield and ultimate stresses are reported along the z (long) axis because experimental test samples are typically oriented along this axis, in uniaxial tension or compression tests, and in bending tests which cause compression and tension along different sides of the long axis. The rationale behind this materials testing practice is that most in-vivo loads of limb elements are assumed to be primarily oriented longitudinally. Sources: R = Reed and Brown (2001), M = Martin et al. (1998), K = Keaveny et al. (2004), L = Linde et al. (1992).

Functional group/muscle	Input F for FEA	Reaction F from FEA	Assumed quiescent	FEA constraint
Ankle extension
M. fibularis longus	✓
M. flexor hallicus longus	✓
M. gastrocnemius (all heads)	✓
Phalangeal flexion			one analysis
M. flexor perforans et perforatus digiti III	✓
M. flexor perforatus digiti III	✓
M. flexor perforatus digiti IV	✓
M. flexor digitorum longus	✓
Phalangeal extension			one analysis
M. extensor digitorum longus	✓
M. extensor proprius digiti III	✓
M. extensor brevis digiti III	✓
M. extensor brevis digiti IV	✓
Ligamentous function
M. fibularis brevis				✓
Hip flexion		✓
Hip extension		✓
Hip adduction		✓
Hip abduction		✓
Knee flexion		✓
Knee extension		✓
Internal rotation		✓
Ankle flexion			✓