Ulnar Claw

What is it?

        The Ulnar Claw, also referred to as claw hand, or “Spinsters Claw” is caused due to a major problem with the ulnar nerve. When attempting to identify the Ulnar Claw, pay close attention to the fingers and what position they are in. The 4th and 5th (ring and little) fingers will be fully elongated at the metacarpophalangeal (MCP) joints while the distal and proximal interphalangeal (IP) joints are flexing. The hand will show hyperextension of the MCP joints and flexion of the distal and proximal IP joints of the 4th and 5th digits.1   

When Does it Show?

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In some cases, ulnar claw is incorrectly referred to as “pope’s blessing,” which is associated with a separate condition caused by median nerve damage that is manipulated by the patient during motor therapy.

Clawing is most apparent when the person flexes the digits from an elongated position, while the little and ring fingers cannot flex because of injury to the ulnar nerve. 1st,2nd, and 3rd digits will only partially flex, visually correlating to a claw-like appearance. Patients who exhibit an Ulnar Claw are also, in most if not all cases, unable to abduct (spread) or adduct (draw together) their fingers against resistance. Over time this physical deficit in patients will be easily identifiable as the paralyzed first dorsal interosseous muscle becomes emaciated, resulting in prominent hollowing between the thumb and index finger.

Where is it most Common?

Damage to the ulnar nerve commonly occurs in the elbow and wrist. Injury to the nerve around the elbow is most common in fractures of the medial epicondyle and is the most common cause of damage to the ulnar nerve. An obvious side effect of nerve damage is the inability to grasp a piece of paper between their fingers. Injury to the ulnar nerve at the wrist is caused by atrophies to the dorsal interossei of the hands. Signs of injury include reduced movement of the little and ring fingers, and development of Ulnar Claw over time.

Is Treatment Possible?

        Though the therapeutic need for a patient with Ulnar Claw will seem to be focused on the extension of the proximal and distal IP joints, it will be most progressive to work on flexion of the MCP joints. The spreading and drawing of the digits and pronation and supination of the forearm can be helpful, as well as stretching the elbow and shoulder. Suggested treatments include a finger splint which should be worn when movement is not necessary to daily routine or function. After reading this blog you should be more than familiar with what Ulnar claw is, know when Ulnar Claw is present, most common sites of injury, and how to treat it. In my next blog I will briefly discuss Contracture Deformity, its common causes, and treatment of the disorder.

References

1Wheeless, C. R., III. (2012, April 11). Ulnar Nerve. Retrieved September 07, 2016, from http://www.wheelessonline.com/ortho/ulnar_nerve

2The Ulnar Nerve. (2016, August 10). Retrieved September 07, 2016, from http://teachmeanatomy.info/upper-limb/nerves/the-ulnar-nerve/

Biomechanics of Human Occupation. (n.d.). Retrieved September 22, 2016, from http://www.mychhs.colostate.edu/david.greene/Functional_Mechanical_Antomy/OT450_PowerPoints/WristHandFinalSlides/NerveDamageOccupationalPerformanceIssuesUpperExtremityHand.htm