The transverse retinacular ligament is a short transverse band running from the flexor tendon sheath and the palmar plate of the PIP joint to the lateral band of the extensor mechanism on each side of the finger. It maintains the lateral bands in a position lateral to the PIP joint axis, preventing them from subluxing dorsally during IP joint extension. Its laxity allows the lateral bands to migrate dorsally in swan-neck deformity and its tightness prevents them from migrating palmarly in boutonniere.
Stabilises the lateral bands of the extensor mechanism in their lateral position at the PIP joint level, preventing dorsal or palmar subluxation; works with the oblique retinacular ligament (Landsmeer) to coordinate PIP and DIP joint motion.
The transverse retinacular ligament plays opposite roles in the two finger deformity patterns: in boutonniere deformity, the transverse retinacular ligament becomes contracted (tight) preventing the dorsally-subluxed lateral bands from returning to their normal position, perpetuating the deformity; in swan-neck deformity, the transverse retinacular ligament becomes lax allowing the lateral bands to migrate dorsally past the PIP joint axis, converting them from PIP extensors to PIP hyperextensors. Releasing the transverse retinacular ligament is part of the surgical correction of chronic boutonniere deformity.
Chronic boutonniere deformity produces secondary contracture of the transverse retinacular ligament and volar displacement of the lateral bands as they sublux palmar to the PIP joint axis; surgical correction requires release of the transverse retinacular ligament to mobilise the lateral bands dorsally back to their normal position lateral to the PIP joint.
