PIP joint volar rotatory dislocation: An anatomical study to explore extensor system lesions and the Stener effect

Area of Science:

• Orthopedic surgery
• Hand surgery
• Biomechanics

Background:

• Volar rotatory dislocation of the proximal interphalangeal (PIP) joint is a complex injury.
• Understanding its precise mechanisms is crucial for effective treatment and surgical planning.

Purpose of the Study:

• To elucidate the biomechanical mechanisms underlying volar rotatory dislocation of the PIP joint.
• To investigate the role of collateral ligament integrity and triangular ligament lesions in dislocation reducibility.

Main Methods:

• A cadaveric study involving thirty-two long finger specimens (digits II-V).
• Simulated volar rotatory dislocation after sequential sectioning of the triangular and radial collateral ligaments.
• Assessment of fixed dislocation, distal triangular ligament extension, and Stener lesions.

Main Results:

• Complete radial collateral ligament sectioning consistently produced a buttonhole lesion of the dislocated lateral band.
• Distal extension of the triangular ligament lesion resulted in irreducible dislocations.
• A Stener effect was observed in 21% of cases with proximal radial collateral ligament lesions.

Conclusions:

• The integrity of the radial collateral ligament and the extent of triangular ligament lesions significantly influence PIP joint dislocation mechanics.
• Distal triangular ligament tears are critical for irreducible dislocations.
• The Stener effect can complicate the reduction of certain collateral ligament injuries.