Distal Interphalangeal Joint (DIP Joint)
- Similar to the PIP joint
- The A5 pulley is attached to the volar plate at this level
- The structures that cross the joint volarly; flexor digitorum profundus and dorsally: the lateral bands
Triangular Ligament
- Function: Counteracts pull of the ORL and prevents subluxation of the common extensor mechanism
- Anatomy: triangular in shape and is located distal to the PIPJ
- Pathology: contracture leads to swan neck deformity
True or False: Knowing the position of the collateral ligaments will ensure you will always respect them during positioning
True: For example, if a patient presents with a cast and the MCP joints are straight and the IP joints are flexed then you must get the cast cut back to allow full MCP joint flexion. Otherwise, the MCP joint collateral ligaments will become shorter and stout, causing active/passive MCP joint flexion to become painful and difficult, if not impossible. Also, in this position you will cause interossei tightness and perhaps lumbrical tightness. In the same breath, if the PIPJ and DIPJ collateral ligaments are not respected and left to flex or dangle over the edge of a cast, fluent movement at the PIPJ and DIPJ is lost and a stiff hand is usually the result.
