Piano Key Sign

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 Piano Key Sign

What is Piano Key Sign?

Piano Key Sign is used to evaluate the stability of the distal radioulnar joint (DRUJ) and triangular fibrocartilage complex (TFCC) of the wrist.

See Also: Distal Radius Fractures

How do you Perform a Piano Key Sign?

Piano Key Sign
Piano Key Sign

What is a positive piano key sign?

Sensitivity & Specificity

A descriptive study by LaStayo and Howell2 found that the Sensitivity & Specificity of Piano Key sign is:

Related Anatomy

Distal Radioulnar Joint DRUJ:

Distal Radioulnar Joint DRUJ
Distal Radioulnar Joint DRUJ

Triangular Fibrocartilage Complex TFCC:

A number of ligaments originate from the TFCC and provide support to it. These include:

  1. The ulnolunate ligament.
  2. Ulnotriquetral ligament.
  3. The ulnar collateral and the radioulnar ligaments.

Other structures that lend support to the TFCC include the following:

  1. The ulnocarpal ligaments.
  2. The sheath of the extensor carpi ulnaris (ECU) tendon, which is the only wrist tendon that broadly connects to the TFCC.

Both the superior and the inferior articular surfaces of the TFCC are smooth and concave. The disk separates the distal ulna from direct contact with the carpals but allows gliding between the carpals, disk, and ulna during forearm pronation and supination.

The TFCC is innervated by branches of the posterior interosseous, ulnar, and posterior (dorsal) sensory ulnar nerves.

Triangular Fibrocartilage Complex TFCC
Triangular Fibrocartilage Complex TFCC


  1. Skirven T: Clinical examination of the wrist. J Hand Ther 9:96–107, 1996.
  2. LaStayo P, Howell J: Clinical provocative tests used in evaluating wrist pain: A descriptive study. J Hand Ther 8:10–17, 1995. PMID: 7742888
  3. Ward LD, Ambrose CG, Masson MV, et al: The role of the distal radioulnar ligaments, interosseous membrane, and joint capsule, in distal radioulnar joint stability. J Hand Surg Am 25:341–351, 2000.
  4. Palmer AK, Werner FW: The triangular fibrocartilage complex of the wrist – anatomy and function. J Hand Surg Am 6:153–162, 1981.

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