Mallet Finger – Diagnosis, Treatment, and Rehabilitation

How to take care of and recover from a common but sometimes vexing finger injury.[1]

Mallet finger usually results from forced flexion of the distal (most distant) part of the finger (distal phalanx – DP) during active extension of the DP. The condition is caused by a rupture of the extensor tendon (on the back of the finger) that crosses the distal interphalangeal joint (DIPJ) from the proximal phalanx (PP) to the DP. Part of the bone may also be avulsed (pulled away). Mallet finger is the most common closed tendon injury in athletes.[2] Often, patients explain that a ball hit their partially flexed fingertip. Patients complain of pain, swelling, and an inability to fully extend their DP.

Splinting the finger in extension continually for at least six weeks (for bony avulsion) or eight weeks (for tendon injury) allows spontaneous reattachment in 80% of patients with mallet finger.[3] A Stack or dorsal splint is typically used, and the splint must be kept on 24/7 for the entire period.[4] The splint should be removed daily to check the skin for breakdown but the joint should remain in complete extension. The torn tendon on the PP must be kept close enough to the remaining tendon on the DP to grow back together. If the PP tendon is moved too far away during the splinting period, even once, it can tear the healing tendon. The process starts over again. The same is true if the injury is caused by a bony avulsion instead of a tendon tear.

Patients who do not begin splinting immediately can still have success with conservative therapy up to three months after injury.[5]  Those who have residual lag after splinting can still see improvement up to six months later. If lag persists after six months, surgical repair should be considered.[6] Untreated mallet finger can progress to swan neck deformity in the finger.

After healing has occurred, rehabilitation is crucial. Twice daily hand therapy helps accelerate recovery in athletes compared to those who do not receive such therapy.[7] Sports medicine recognizes three phases of rehabilitation: 1) acute, 2) recovery, and 3) functional.[8] In the acute phase, patients and their caregivers use rest, immobilization, medication, and manual therapy to control pain, swelling, and inflammation, prevent reinjury, and maintain or regain range of motion. In the recovery phase, patients use manual therapy and specific, progressive exercises to restore function and regain local flexibility and strength. In the functional phase, patients use activity specific exercise to regain strength, flexibility, and skills.

In mallet finger injuries, the acute phase includes the time of splinting or surgery to reattach the tendon, and the immediate aftermath. Patients will sometimes lose significant range of motion during immobilization. A key goal in the recovery phase is to regain normal motion. Passive movement occurs when one part of the body moves another part. In this case, a patient or caregiver could carefully grasp the injured finger to move it. Gentle passive flexion and extension of the finger at the PIPJ and DIPJ within a limited range of motion is a good start. Over several days, the passive range of motion (PROM) can be increased as long as pain and swelling do not recur. PROM ends once the patient has a full active range of motion.

Active range of motion (AROM) occurs when a body part, such as an injured finger, moves itself. If PROM is going well without complications, AROM can begin. The goal is to return to full AROM, including full flexion and full extension, in the PIPJ and DIPJ of the injured finger. Once pain, swelling, and range of motion are normal, therapy targets muscular rehabilitation until the strength in the injured side is comparable to the strength in the same finger in the uninjured side.

Strength retraining begins isometrically, meaning that the finger muscles contract against fixed, immobile resistance. For example, a patient may flex and extend his finger against a table or chair for 30 seconds. Exercise the PIPJ and DIPJ separately and then together. Isokinetic exercise, moving the affected finger against resistance over an ever-larger range of motion, comes next. Grip strength and actively moving fingers side to side (abduction and adduction) are good hand-specific exercises.

The functional phase returns the patient to normal function during the activities of daily living. For a finger, this involves whatever fine motor and other movements the finger normally does.  The goal is person specific, as a baseball player with mallet finger will likely have different goals than a concert pianist. Normal neurological function, including normal sensation, if it was ever impaired, should also be returning. Patients should be sure to protect the finger during its recovery.

Conclusion

Mallet finger occurs without warning but takes weeks or months to heal and rehabilitate. Conservative therapy has high rates of success and low rates of complications. Compliance with therapy is critical for the best outcomes, but compliance is hard to do in the real world. Physicians and patients do best to partner, and keep working together, to get the best outcomes for the patient.

[1] Image courtesy of Netter’s Sports Medicine, 2nd edition. 2009

[2] Elzinga KE, Chung KC. Finger Injuries in Football and Rugby. Hand Clin. 2017 Feb;33(1):149-160. doi: 10.1016/j.hcl.2016.08.007. PMID: 27886831; PMCID: PMC5125556.

[3] Seidenberg, P. H., & Beutler, A. I. (2008). Chapter 19: Soft Tissue Injuries of the Hand and Wrist, The Sports Medicine Resource Manual. Saunders/Elsevier. P 200-201

[4] Madden, C., Putukian, M., Mccarty, E., & Young, C. (2009). Netter’s Sports Medicine. W B Saunders Co.

[5] Seidenberg, P. H., & Beutler, A. I. (2008). Chapter 19: Soft Tissue Injuries of the Hand and Wrist, The Sports Medicine Resource Manual. Saunders/Elsevier. P 200-201

[6] Seidenberg, P. H., & Beutler, A. I. (2008). Chapter 19: Soft Tissue Injuries of the Hand and Wrist, The Sports Medicine Resource Manual. Saunders/Elsevier. P 200-201

[7] Elzinga KE, Chung KC. Finger Injuries in Football and Rugby. Hand Clin. 2017 Feb;33(1):149-160. doi: 10.1016/j.hcl.2016.08.007. PMID: 27886831; PMCID: PMC5125556.

[8] Seidenberg, P. H., & Beutler, A. I. (2008). Chapter 19: Soft Tissue Injuries of the Hand and Wrist, The Sports Medicine Resource Manual. Saunders/Elsevier. P 432-433.

Author: MD Harris Family Institute

MD, MPH, MBA, MDiv, PhD, ThM, DECBA Colonel, US Army (ret)

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