What Is Ulnar Drift?

Ulnar Drift Is a Common Characteristic of Rheumatoid Arthritis

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Ulnar Drift Explained

Ulnar drift, also referred to as ulnar deviation, is a deformity of the fingers of the hand. Specifically, ulnar drift occurs when there is ulnar deviation and volar subluxation of the metacarpophalangeal joints (MCP). Anatomically, the proximal phalanges join with the metacarpals of the hand at the metacarpophalangeal joints. The MCP joints are more commonly referred to as the knuckles.

Volar subluxation of the metacarpophalangeal joint develops when there is partial dislocation of the joint -- the proximal phalanx shifts away from the metacarpal head, moving in the palmar direction. Intermediate and distal phalanges follow the shifting movement of the proximal phalanx.

According to Kelley's Textbook of Rheumatology, there is evidence that rheumatic disease of the wrist leads to ulnar deviation of the MCP joints. It is thought that weakening of the extensor carpi ulnaris muscle causes radial deviation of the wrist as carpal bones rotate (proximal carpal bones rotate in a ulnar direction and distal carpal bones in a radial direction). Ulnar deviation develops as a physical response, attempting to keep the tendons to the phalanges in alignment with the radius. Erosion of bone or articular cartilage may contribute to ulnar drift, but it also may occur without either. Synovitis and muscle weakness can play a role in its development.

  

Early signs of ulnar drift include:

  • weakness of the first dorsal interossei (interossei are the muscles between specific bones)
  • laxity of radial collateral ligaments
  • tightening of intrinsic muscles
  • ulnar displacement of flexor tendons (prominant in index and longer fingers)
  • ulnar deviation of fingers which is evident when MCP joints are extended

    Advanced signs of ulnar drift include:

    • volar subluxation (partial dislocation) of phalanges
    • inability to fully extend MCP joints resulting in flexion contracture
    • ulnar slip or shift of extensor tendons
    • tightening of hypothenar muscles (a group of three muscles in the palm of the hand that control movement of the little finger)
    • radial deviation of wrist
    • extensor carpi ulnaris tendon dislocation
    • loss of ability for thumb to oppose the index finger

    To assess the severity of ulnar drift, a goniometer may be used. The stationary arm of the goniometer is placed over the metacarpal while the moveable arm is placed parallel to the proximal phalange. After the degree of deformity is determined, the patient is usually asked to straighten their hand, if possible, to actively correct the alignment and a re-measurement is taken. Other hand function tests may also be used to evaluate severity of the deformity.

    Who Develops Ulnar Drift?

    Ulnar drift is primarily associated with rheumatoid arthritis. Chronic inflammation of the MCP joints damage the joint capsule and surrounding structures.

    But, rheumatoid arthritis is not the only condition connected with ulnar drift. It may occur with other inflammatory conditions or connective tissue diseases, such as lupus or psoriatic arthritis. One case study also revealed an association with the uncommon disorder, pigmented villonodular synovitis (PVNS).

    Treatment Options

    Options for treating hand swelling and pain include ice, moist heat, paraffin wax baths, TENS unit, and ultrasound. Hand exercises, which primarily involve stretching, are recommended to preserve range of motion as much as possible. 

    Splinting is sometimes recommended to reduce subluxation of the wrist, to properly position MCP joints in neutral radial-ulnar alignment, and reduce subluxation of the MCP joints by supporting proximal phalanges. Generally, the splints are worn at night or during rest periods in the daytime. Splints may help with pain at night but splints have not been shown to prevent ulnar deviation. Even with nighttime splinting, ulnar deviation may progress.

    Sources:

    Kelley's Textbook of Rheumatology. Ninth edition. Firestein et al. Elsevier Saunders. Clinical Features of Rheumatoid Arthritis. Chapter 70. Hands and Wrists. Page 1112.

    Volar Subluxation of Metacarpophalangeal Joint. Accessed 11/17/14.
    http://mychhs.colostate.edu/David.Greene/volar_sublux_mcp.htm

    Best Practice Recommendations for Management of Ulnar Drift Deformity in Rheumatoid Arthritis. Vancouver Coastal Health. The Arthritis Society (Canada). Accessed 11/17/14.

    The Usefulness of Nocturnal Resting Splints in the Treatment of Ulnar Deviation of the Rheumatoid Hand. Johnson M et al. Clinical Rheumatology. March 1992.
    http://www.ncbi.nlm.nih.gov/m/pubmed/1582123/

    Ulnar Deviation Is Not Always Rheumatoid. Zuber M et al. Annals of the Rheumatic Diseases. 1996.
    http://ard.bmj.com/content/55/11/786.full.pdf

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