Types of subtalar joint facets

Area of Science:

• Anatomy
• Biomechanics
• Orthopedics

Background:

• The clinical subtalar joint (CSTJ) is crucial for foot and ankle biomechanics.
• Understanding the morphology of CSTJ articular facets is essential for diagnosing and treating foot pathologies.

Purpose of the Study:

• To classify the types of articular facets in the clinical subtalar joint (CSTJ).
• To analyze the continuity and fusion patterns of CSTJ facets in Korean adult cadavers.
• To investigate the relationship between facet morphology and joint mobility/stability.

Main Methods:

• Analysis of 118 dry, paired calcanei and tali from 68 Korean adult cadavers.
• Classification of CSTJ facets into three types (A, B, C) based on continuity.
• Quantification of facet separation using the degree of separation (DS) metric.
• Matching of calcaneus-talus pairs to determine combined facet types.

Main Results:

• Three CSTJ facet types (A, B, C) were identified, with Type A most common in calcanei and Type C showing fusion.
• Combined calcaneus-talus pairs revealed five types (A-A, A-B, B-B, B-C, C-C), with A-B and C-C being most frequent.
• A smaller degree of separation (DS) correlated with increased facet fusion, particularly in tali.
• Inverse relationship observed between DS and intersecting angles, suggesting impact on mobility.

Conclusions:

• The anterior and middle facets of the CSTJ fuse more frequently in tali than in calcanei.
• Over 40% of feet exhibit combinations of different CSTJ facet types.
• Facet types with smaller DS (more fused) are associated with greater mobility but reduced stability.