midtarsal joint-restraining mechanism

midtarsal joint-restraining mechanism

effect of sagittal-plane orientation of midtarsal joint components on foot function during stance (Table 1)
Table 1: The influence of the sagittal-plane orientation of the components of the midtarsal joint on foot function during stance
Pronation (early stance)Supination (late stance)
Sagittal-plane orientation of TN and CC jointsOblique to sagittal plane (TN joint medial to CC joint)Oriented towards sagittal plane (TN joint relatively superior to CC joint)
TN/CC joint axesAligned; coincident
Allows greatest freedom of movement of navicular and cuboid
Non-aligned; oblique
Restricts movement of navicular and cuboid
STJ ligamentous structuresLaxTense
Range of motion at STJIncreasedReduced
Effect on foot during weight-bearingMTJ elements non-close-packed
Reduced height of MLA (elongation of foot)
Increased shock absorption
Adaptation to ground surface irregularity
MTJ elements close-packed
Increased height of MLA
Decreased shock absorption
Rigid base
Effective toe off

TN, talonavicular; CC, calcaneocuboid; STJ, subtalar joint; MTJ, metatarsal joint; MLA, medial longitudinal arch.