Alteration in articular cartilage in subtalar coalition: A comparative analysis

Area of Science:

• Orthopedics
• Radiology
• Anatomy

Background:

• Subtalar coalition (SC) is a rare condition involving abnormal connections between the talus and calcaneum.
• SC can manifest as osseous, fibrous, or cartilaginous forms, each impacting clinical presentation and management strategies.
• Articular cartilage thickness in the subtalar joint is crucial for understanding degenerative changes and guiding surgical decisions, yet remains understudied in various SC types.

Purpose of the Study:

• To analyze and compare articular cartilage thickness in the posterior facet of the subtalar joint (PFSJ).
• To investigate differences in cartilage thickness among patients with normal joints, osseous subtalar coalition, and fibrous subtalar coalition.

Main Methods:

• A retrospective analysis of foot and ankle MRI and CT scans was conducted.
• Articular cartilage thickness of the PFSJ was measured in patients with normal joints, osseous coalition, and fibrous coalition.
• Statistical analysis using ANOVA was performed with a significance level of p < 0.05.

Main Results:

• Articular cartilage was significantly thicker in the fibrous subtalar coalition group (2.3 mm) compared to normal (1.7 mm) and osseous coalition (1.4 mm) groups across all measured regions.
• Osseous subtalar coalition was associated with relative cartilage thinning in all regions compared to both fibrous coalition and normal joints.

Conclusions:

• Fibrous subtalar coalition is characterized by relative articular cartilage hypertrophy.
• Osseous subtalar coalition is linked to relative cartilage thinning, suggesting reduced joint loading and potential early osteoarthritis.
• These findings have significant clinical implications for surgical management, differentiating between excision for preserved cartilage and fusion for thinned cartilage.