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 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
- Nerve compression
Factors that may increase your chance of an extensor tendon injury include:
Participating in certain sports
Symptoms may include:
- Inability to open hand or fingers
- 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-ray.
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:
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.
After surgery, you will be given a splint to protect your hand. You will be told how long to wear it. It may be up to two months.
A physical therapist or occupational therapist will work with you for several weeks to regain your strength and range of motion. Right after surgery, movement will be limited. This will allow your hand to heal.
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
The Canadian Orthopaedic Association
Canadian Orthopaedic Foundation
Extensor tendon injuries. American Society for Surgery of the Hand website. Available at: http://www.assh.org/Public/HandConditions/Pages/ExtensorTendonInjuries.aspx. Accessed September 25, 2014.
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.
Last reviewed August 2015 by Warren A. Bodine, DO, CAQSM
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.