Fig. 4From: Mathematical analysis in the design of digital artery-based V–Y advancement flap in treating proximal interphalangeal joint flexion contractureIllustration of the volar view of the PIP joint anatomy. The proper collateral ligament (yellow) is preserved intraoperatively to maintain joint stability. The accessory collateral ligaments, checkrein ligaments, and proximal margin of the volar plate (green) are released. MCPJ = metacarpophalangeal jointBack to article page