Unlike flexor tendon injuries, many extensor tendon lacerations do not require surgery — a well-fitted splint is often the right treatment. When surgery is indicated, Dr. Graham uses local anesthesia so he can ask patients to actively extend the finger intraoperatively, confirming the repair is strong and correctly tensioned before the wound is closed.
Mallet finger and boutonnière deformity are related but distinct injuries — each has its own dedicated page.
Understanding the Injury
The extensor tendons run along the back of the hand and fingers, straightening the joints that the flexor tendons bend. They arise from muscles in the forearm, cross the wrist under the extensor retinaculum, fan out across the hand, and insert on the finger bones through an intricate structure called the extensor mechanism.
Extensor tendons lie just beneath the skin on the dorsum of the hand and fingers — there is very little soft tissue between them and the surface. This makes them vulnerable to even shallow lacerations, but it also means they are more accessible and, in many zones, amenable to non-surgical management.
The nature of extensor tendon injuries differs fundamentally from flexor injuries. Extensor tendons don't retract as dramatically when cut — the extensor mechanism has intrinsic tension and interconnections that often hold the ends in reasonable proximity. In appropriate zones, a splint that holds the finger or wrist in extension allows the tendon ends to rest against each other and heal without surgical intervention.
In Dr. Graham's experience, the most important first step is an accurate assessment of which tendon is injured, in what zone, and how completely. That evaluation determines whether you leave the office with a splint or a surgery date.
Extensor tendon zones are numbered I–VIII distally to proximally. Zone V — over the MCP joint — is the most common site of laceration and the most important to evaluate carefully for joint penetration.
Mallet finger (Zone I) and boutonnière deformity (Zone III central slip) are covered in their own dedicated pages.
Recognizing an Extensor Tendon Injury
Extensor injuries present differently depending on the zone. The common thread is inability to fully straighten a finger, the wrist, or both.
The clearest sign. With the hand resting palm-down, an affected finger will lag behind the others — it won't fully extend, or can only be brought to neutral with effort. The degree of lag reflects how much of the tendon is intact.
Any cut on the back of the hand, finger, or wrist should prompt evaluation of the underlying extensor tendon. Because the tendons lie so superficially, lacerations that appear minor on the surface can transect the tendon completely.
Lacerations at the wrist and distal forearm (Zones VII–VIII) may impair wrist extension rather than — or in addition to — finger extension. The patient may notice the wrist dropping or feeling weak against resistance.
A laceration over the MCP joint from a punch to someone's teeth is a surgical emergency — not because of the tendon, but because of joint penetration and inoculation with oral flora. These wounds require urgent washout regardless of tendon involvement. The tendon repair is secondary to infection prevention.
Dog and cat bites over the dorsum of the hand carry significant infection risk and must be evaluated promptly. Any bite that reaches the extensor tendon — or the joint — requires washout. Delayed presentation of a bite wound over a joint is a hand surgery emergency.
A partial extensor tendon laceration may allow near-normal extension initially. Without treatment, continued use can propagate the tear to a complete rupture. Any dorsal hand laceration with even subtle weakness or asymmetry warrants formal evaluation, not watchful waiting at home.
Treatment Decision
This is the central question with extensor tendon injuries. The answer depends on the zone, the degree of laceration, the wound environment, and what the patient needs to do with their hand.
Because extensor tendons don't retract as aggressively as flexors, a well-fitted splint that holds the involved joint in extension can bring the tendon ends into apposition and allow healing without surgery. In Dr. Graham's experience, splinting is appropriate — and produces excellent results — in a wide range of extensor injuries.
Splinting is a real treatment — not a delay. Worn correctly and consistently, it is frequently definitive.
More proximal lacerations — particularly in Zones V through VIII over the knuckle, hand, wrist, and forearm — are more likely to require surgical repair. The tendon ends are under greater tension in these zones and cannot reliably be held in apposition by external splinting.
When Surgery Is Performed
Surgery is performed under local anesthesia — allowing real-time confirmation that the repair moves correctly before the wound is closed.
Dr. Graham performs extensor tendon repairs using WALANT (wide-awake local anesthesia, no tourniquet). With the patient awake and comfortable, he can ask them to actively extend the finger or wrist at any point during the procedure.
This matters because extensor repair tension is critical and difficult to judge statically. Too tight — and the repair limits flexion. Too loose — and an extension lag remains. By testing active extension intraoperatively, Dr. Graham can verify the repair is correctly balanced before closure. No guesswork, no surprises in the recovery room.
If a nerve is injured alongside the tendon, it is repaired under loupe magnification at the same setting.
Local anesthetic is injected into the hand or finger. No tourniquet, no general anesthesia required. The patient is awake throughout and able to follow commands. For wounds requiring extensive washout — fight bites, contaminated lacerations — this also allows assessment of joint integrity without sedation.
The wound is extended as needed and the zone of injury is assessed directly. For bite wounds or grossly contaminated lacerations, thorough irrigation precedes any tendon work. Joint capsule integrity is confirmed — penetration of the MCP or PIP joint changes the urgency and management of the case significantly.
The tendon ends are identified, freshened if needed, and repaired with suture. The specific technique varies by zone — extensor tendon repair is technically less demanding than flexor repair, but correct tension and alignment matter. Dr. Graham uses loupe magnification throughout.
The patient is asked to extend the finger or wrist. Dr. Graham observes the repair directly — confirming full extension is achievable, that no lag remains, and that flexion is not restricted by an overtightened repair. Any adjustment is made before closure. This step is what makes WALANT valuable for extensor repairs specifically.
The wound is closed in layers. A splint is applied in an appropriate position of extension to protect the repair during early healing. Unlike flexor tendon repairs — where Dr. Graham often foregoes bracing — extensor repairs are typically splinted post-operatively for a defined period based on the zone and repair quality.
"Fred Alvarez called Dr. Graham his go-to guy — not just for the result, but for how straightforward everything was. No runaround, just answers and a plan."
Fred Alvarez · Hand Surgery Patient · Verified Google Review ★ 5/5
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