Extensor tendons lie just beneath the skin on the back of the hand and fingers. They have a relatively poor blood supply, making them susceptible to injury and challenging to repair. When an extensor tendon is cut or torn, the injury often results in an inability to fully extend the affected finger or thumb. Healing requires the body to move through distinct biological stages to restore structural integrity and function.
The Biological Stages of Extensor Tendon Healing
The body’s response to an extensor tendon injury follows three overlapping phases.
The initial Inflammatory Phase begins immediately following the injury and typically lasts for the first five days. Blood clots form at the injury site, and immune cells clear damaged tissue to initiate repair. The repaired tendon is at its weakest during this phase, held together only by sutures or the initial soft clot.
The Proliferative Phase commences around day five and continues for up to four weeks. Fibroblasts begin producing new collagen fibers to bridge the gap in the tissue. This new tissue is primarily disorganized Type III collagen, which lacks the strength of the original tendon. The tendon remains vulnerable to re-rupture if excessive force is applied.
The final and longest stage is the Remodeling Phase, which begins around four weeks and can continue for a year or more. Disorganized Type III collagen is gradually replaced by stronger, more mature Type I collagen. The fibers align themselves parallel to the direction of stress, significantly increasing the tendon’s tensile strength. This phase determines the long-term functional outcome, transitioning the repair site into a durable, functional structure.
Typical Recovery Timelines Based on Injury Type
The timeline for functional recovery depends on the specific injury type and treatment method.
For injuries treated Non-Operatively, such as a Mallet finger injury where the tendon pulls away from the fingertip bone, continuous splinting is the standard approach. Immobilization must be maintained without interruption for a minimum of six to eight weeks to allow the tendon ends to scar together. Following this, a period of night splinting and gradual movement is necessary, meaning full recovery of range of motion can take three to four months.
In cases requiring Surgical Repair for a lacerated tendon, the timeline is structured around protecting the delicate suture line. Initial post-operative immobilization typically lasts three to six weeks, depending on the injury zone and surgical protocol. This protective phase is when the tendon is weakest, and movement is strictly controlled by a hand therapist.
The four-to-six-week mark serves as the initial healing benchmark, signifying that the repair site is structurally sound enough to begin controlled, active movement. While the tendon is biologically connected by four to six weeks, the tensile strength required for normal, unrestricted activity is not achieved until approximately 12 weeks post-injury. Patients can anticipate a return to light activities after two to three months, but achieving maximum functional recovery often spans six months to a full year.
Critical Factors Influencing Healing Speed
Several biological and behavioral variables influence healing timelines. Injury Characteristics are important; wounds in the distal zones of the fingers, where blood supply is poorer, may heal slower than those closer to the wrist. Associated injuries, such as bone fractures or joint damage, complicate the process and may necessitate longer immobilization.
The patient’s overall Vascular Health directly impacts healing speed, given the tendon’s limited blood supply. Systemic conditions like uncontrolled diabetes or poor circulation impair the body’s ability to deliver nutrients and immune cells to the repair site.
Lifestyle Factors can introduce delays, particularly nicotine use. Nicotine constricts blood vessels, reducing blood flow and oxygen delivery, which interferes with collagen synthesis required during the proliferative phase. Adherence to the prescribed post-injury protocol is also important, as non-compliance with splinting or early, forceful movement can lead to re-rupture, forcing the entire healing timeline to restart.
The Role of Rehabilitation in Restoring Function
Rehabilitation is necessary for restoring full functional use of the hand and fingers. The primary goal of therapy is to prevent dense Adhesions, which occur when the healing tendon sticks to surrounding tissues, limiting its ability to glide freely. Hand therapy typically begins within the first week following surgical repair to initiate controlled motion.
Therapists employ Controlled Passive and Active Motion exercises, often using specialized splints to protect the repair while enabling restricted movement. Dynamic splinting, for example, uses elastic traction to gently pull the finger into a protected position while allowing the patient to actively flex the digit. This controlled stress guides collagen fibers to align properly and helps the tendon develop the necessary excursion for full range of motion. Functional recovery, including regaining strength and fine motor control, is a gradual process that often requires three to six months or more.