Procedures · Hand & Upper Extremity Surgery

Extensor Tendon Injury

Medically reviewed by Dr. Khalid Almutairi, Consultant Plastic Surgeon — updated 2026-08-13

The extensor tendons run along the back of the hand and fingers to straighten them. They lie closer to the skin than the flexor tendons, so relatively minor cuts can injure them — and they can rupture without any wound at all, from a blow to the fingertip. The result is the same: a finger or a joint that will not fully straighten.

Care is led by Dr. Khalid Almutairi, a consultant plastic and reconstructive surgeon, fellowship trained in hand surgery and microsurgery in Canada and the USA.

Common patterns worth knowing

The injury looks different depending on its level along the tendon:

• Mallet finger: the fingertip droops and will not straighten after a blow to its tip — a ball injury, typically — because the tendon has pulled off at its attachment to the last bone. Many of these closed injuries are treated with continuous splinting alone when diagnosed early.
• Boutonnière deformity: when the tendon's central slip is injured over the middle joint, that joint sinks into flexion while the end joint overextends. Early recognition matters, because neglect fixes the deformity in place.
• Lacerations over the back of the hand or fingers: these frequently divide the tendon partly or completely and may reach the joint — and joint wounds from a punch against teeth are treated with particular care because of the infection risk.
• Rupture in joint disease: as in the rheumatoid hand, where the tendon frays over roughened bone — this has its own page.

Assessment

The doctor tests the straightening of each joint individually — some injuries are masked by compensating pull from neighbouring tendons — assesses the wound, its depth, and whether it may reach the joint, and excludes associated fractures with X-rays where needed.

Treatment: splint where splinting works, surgery where it doesn't

Not every extensor injury is surgical. A closed mallet finger diagnosed early is usually treated with weeks of continuous splinting that keeps the end joint straight — and the patient's adherence to the splint is the treatment itself. Lacerations, by contrast, usually need surgical repair of the tendon, with treatment of any associated joint injury. In late or neglected injuries, grafting, tendon transfer, or correction of an established deformity may be required, assessed individually.

Rehabilitation and splinting

Each injury level has its own splinting and exercise programme, balancing protection of the repair against adhesions and stiffness. The hand therapist's programme and individual instructions are the reference, and completing the full splinting period — especially in mallet finger — is a condition of the result.

Recovery and expectations

The tendon heals over weeks and movement is rebuilt gradually afterwards. A small residual lack of full straightening (extensor lag) may remain in some patients even with correct treatment, and this is discussed frankly from the start.

Limitations and risks

Risks include adhesions and stiffness, residual extensor lag, recurrence of the droop in mallet finger if the splint is stopped early, infection in joint wounds, and the need for later release or correction in some cases. The risks relevant to your case are discussed before any decision.

A ball hit my fingertip and the tip droops — do I need surgery?

Many closed mallet finger injuries are treated with a splint alone when diagnosed early. What matters is not delaying assessment — delay narrows the options.

Can a minor extensor injury be left untreated?

Neglect can turn a simple problem into an established deformity that is harder to correct. Early assessment is quick and simple, and it preserves your options.

When can I return to work?

It depends on the injury and the work: desk-based work often within days while wearing the splint, manual work once the doctor advises. Individual instructions are the reference.

Medical-information notice

This is general information and does not replace consultation and examination. Joint wounds — especially after a punch against teeth — need urgent assessment because of the infection risk.