• Finger Extensor Tendon Injury

    (Mallet Finger; Boutonniere Deformity)


    Tendons are responsible for connecting muscles to bone. The extensor tendons are located on the back of the hand and fingers. They let you open your hand and straighten your fingers. An extensor tendon injury is a cut or tear to one of these tendons. When they are damaged, you can lose the ability to extend your hand and/or finger(s). Two common extensor injuries are:
    • Mallet finger—the tendon is affected at the last joint on the finger, usually from a jammed finger
    • Boutonniere deformity—the tendon is affected at the middle joint, usually caused by an arthritis-like condition
    Extensor Tendons of the Hand
    extensor tendon
    Copyright © Nucleus Medical Media, Inc.


    Extensor tendon injuries may be caused by:
    • A cut or laceration to back of hand or fingers
    • Broken bones
    • A crush injury
    • An open wound or cut
    • Jamming a finger
    • Arthritis
    • Nerve compression

    Risk Factors

    Factors that may increase your chance of an extensor tendon injury include:
      Participating in certain sports, such as:
      • Basketball
      • Football
    • Arthritis


    Symptoms may include:
    • Inability to open hand or fingers
    • Pain
    • Numbness or weakness
    • Cut to back of the hand or fingers
    • Jammed finger


    You will be asked about your symptoms and medical history. A physical exam will be done. During the exam, you will be asked to bend and straighten your fingers. Your doctor will also check your fingers for sensation, blood flow, and strength. You may be referred to a hand surgeon or an orthopedist—doctor who specializes in bones.
    Images may be taken of your hand. This can be done with x-rays.


    Talk with your doctor about the best plan for you. Depending on the type of injury, you may require surgery. Surgery may be scheduled right away or within several days.
    Treatment options include the following:


    Depending on the type of injury, antibiotics may be given to prevent infection.


    Tendons that are cut or ruptured require surgery. The hand surgeon may sew the tendon back together. A pin may need to be inserted through the bone to form a type of inside splint.
    A splint may be worn after surgery to protect the hand. A physical therapist or occupational therapist can help regain finger strength and range of motion.


    Some extensor tendon injuries are treated with a hand splint. Splints are worn until healing has occurred. This is usually several weeks.


    Extensor tendon injuries are typically caused by accidental injuries. There are no known prevention guidelines for this injury.


    American Society for Surgery of the Hand http://www.assh.org

    Ortho Info—American Academy of Orthopaedic Surgeons http://orthoinfo.aaos.org


    Canadian Orthopaedic Association http://www.coa-aco.org

    When it Hurts to Move—Canadian Orthopaedic Foundation http://whenithurtstomove.org


    Extensor tendon injuries. American Society for Surgery of the Hand website. Available at: http://www.assh.org/Public/HandConditions/Pages/ExtensorTendonInjuries.aspx. Accessed August 24, 2017.

    Leggit JC, Meko CJ. Acute Finger Injuries: Part I. Tendons and Ligaments. Am Fam Physician. 2006 Mar 1;73(5):810-816. Available at: http://www.aafp.org/afp/2006/0301/p810.html. Accessed September 25, 2014.

    To P, Watson JT. Boutonniere deformity. J Hand Surg Am. 2011;36(1):139-142.

    Zhang X, Yang L, et al. Treatment of bony boutonniere deformity with a loop wire. J Hand Surg Am. 2011;36(6):1080-1085.

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