Finger Extensor Tendon Injury
(Mallet Finger; Boutonniere Deformity)
by Patricia Griffin Kellicker, BSN
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:
Extensor tendon injuries may be caused by:
Risk Factors TOP
Factors that may increase your chance of an extensor tendon injury include:
Symptoms may include:
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
Ortho Info—American Academy of Orthopaedic Surgeons
Canadian Orthopaedic Association
When it Hurts to Move—Canadian Orthopaedic Foundation
Extensor tendon injuries. American Society for Surgery of the Hand website. Available at:
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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:
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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.
Last reviewed September 2018 by EBSCO Medical Review Board Warren A. Bodine, DO, CAQSM
Last Updated: 9/25/2014
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