Flexor Tendon Lacerations & Repair

What Are Flexor Tendon Injuries?

Flexor tendons are the cordlike structures that connect the muscles in your forearm to the bones in your fingers and thumb. When these muscles contract, they pull on the tendons, which bend your fingers and allow you to make a fist, grip objects, and perform fine motor tasks. Each finger has two flexor tendons running along the palm side, traveling through narrow tunnels lined with a slippery coating that helps them glide smoothly.

When a flexor tendon is cut or lacerated, you lose the ability to bend part or all of the affected finger. The muscle can contract, but without the tendon connection, the force doesn't reach the bone. These injuries most commonly result from cuts to the palm, fingers, wrist, or forearm. Because flexor tendons lie close to important nerves and blood vessels, these structures are often injured at the same time, requiring comprehensive repair.

Symptoms

The primary symptom is an inability to bend one or more joints in your finger or thumb after a laceration. The specific joints affected depend on where along the tendon the injury occurred. If you cannot make a fist or bend a finger, even though you're trying, the flexor tendon is likely cut. This loss of function is immediate and complete at the affected joints.

Because flexor tendons run alongside nerves and arteries, you may also experience numbness, tingling, or loss of sensation in the affected finger. Significant bleeding is common, as the arteries that supply blood to the fingers travel in the same narrow channels as the tendons. Even relatively small cuts on the palm or finger can injure these vital structures, so any laceration that affects your ability to move your fingers should be evaluated promptly.

The wound itself may not look particularly severe. Flexor tendon injuries can occur from relatively small cuts that happen to be in exactly the wrong location. Don't assume an injury is minor just because the cut looks small. Any change in finger function after a laceration warrants immediate medical attention.

Causes & Risk Factors

Lacerations are by far the most common cause of flexor tendon injuries. Kitchen knives, broken glass, power saws, box cutters, and other sharp objects can cut these tendons. Workplace injuries are common in people who handle sharp tools or equipment. Even a moment of inattention while cutting food, opening packages, or working with tools can result in a deep laceration that severs a tendon.

Sometimes flexor tendons can rupture without a laceration. This is less common but can occur if the tendon pulls away from its attachment to bone, if the tendon itself tears due to degeneration, or if the muscle-tendon connection separates. These non-laceration injuries might happen during forceful gripping or pulling activities, though they're rare compared to cuts.

Anyone can experience a flexor tendon laceration, though people who work with sharp objects or power tools are at higher risk. Wearing protective gloves when handling sharp objects can reduce your risk, though even with precautions, accidents can happen. The key is recognizing when an injury may involve a tendon and seeking evaluation immediately.

Diagnosis

If you have a laceration and cannot bend part of your finger, seek evaluation by a hand surgeon right away. During the examination, your surgeon will test each finger joint individually to determine which tendons are injured. They'll also check sensation to see if nerves are damaged and assess blood flow to ensure the arteries are intact. Even if you can bend your finger slightly, the tendon may be partially cut and at risk of rupturing completely.

X-rays may be taken to look for foreign bodies in the wound, such as glass fragments, and to check for fractures. The full extent of the injury often can't be determined until the wound is explored in the operating room under proper lighting and anesthesia. It's not uncommon to find that multiple structures are injured, requiring comprehensive repair of tendons, nerves, and arteries.

Treatment Options

Flexor tendon lacerations do not heal on their own and virtually always require surgery to repair. Unlike some other injuries that can be managed conservatively, a cut tendon needs to be sewn back together to restore function. The sooner the repair is performed after injury, generally the better the outcome. If you suspect a flexor tendon injury, seek evaluation by a hand surgeon as soon as possible.

Timing of surgery depends on several factors. Clean, recent lacerations are often repaired within the first few days after injury. If the wound is contaminated or there's a delay in seeking treatment, the surgery may be performed after the wound has been cleaned and any infection treated. Your surgeon will determine the best timing based on your specific situation.

During surgery, the tendon ends are carefully sewn back together using specialized techniques. Any injured nerves or arteries are repaired at the same time. After surgery, your hand is placed in a protective splint, and you'll begin a carefully controlled rehabilitation program guided by your surgeon and hand therapist. The rehabilitation is critical for success because the tendon needs to glide smoothly while it heals, which requires specific exercises at specific times.

Surgery: What to Expect

Flexor tendon repair is typically performed as an outpatient procedure under local anesthesia, with sedation available for select cases if needed. The operation usually takes one to two hours, depending on how many structures are injured. The surgeon works under magnification to achieve a precise repair.

The wound is extended as needed to find both ends of the cut tendon. The tendon ends are carefully prepared and then sewn together using strong sutures and specialized techniques designed to allow early motion while providing enough strength to hold the repair together. If nerves or blood vessels are injured, these are repaired using microsurgical techniques. Sometimes the wound cannot be fully closed and requires a skin graft.

After surgery, your hand is placed in a special splint that protects the tendon repair while allowing controlled motion. The splint typically holds your wrist and fingers in a partially bent position to take tension off the repair. You'll begin a specific exercise program within the first few days after surgery, supervised by a hand therapist.

Recovery

Recovery from flexor tendon repair is a long process that requires dedication and patience. The rehabilitation program is critical to success. Hand therapy typically begins within days of surgery and continues for several months. Early motion is important to prevent the tendon from getting stuck in scar tissue, but the motion must be carefully controlled to avoid rupturing the repair.

You'll receive a home exercise program with very specific exercises that must be performed multiple times per day. These exercises are designed to gently glide the tendon while protecting the repair. Your hand therapist will work closely with you to ensure you understand and follow the protocol correctly. Most patients work with a therapist regularly during the first several weeks, then transition to more independent home exercises as healing progresses.

The tendon repair needs about six weeks to gain enough strength to tolerate normal use. During this time, you must avoid any forceful gripping, pulling, or lifting with the injured hand. Strengthening exercises begin after the initial healing period and continue for several months. Most people regain good function, though recovery can take six months or longer.

Complications can occur despite excellent surgery and rehabilitation. Scarring and stiffness are the most common problems. The tendon can become stuck in scar tissue, limiting how much the finger bends. Additional surgery to release scar tissue is sometimes needed. Occasionally the tendon repair ruptures during healing, requiring another operation. Following your surgeon's and therapist's instructions carefully gives you the best chance for a successful outcome.

When to See a Specialist

Any laceration to your hand, wrist, or fingers that results in difficulty bending your fingers requires urgent evaluation by a hand surgeon. Don't wait to see if function returns on its own. The timing of treatment can significantly impact your outcome. Even if you can bend your finger partially, the tendon may be damaged and need repair.

Dr. Lackey specializes in microsurgical repair of flexor tendon injuries and works closely with hand therapists to optimize outcomes. Early evaluation and treatment provide the best opportunity for restoring full function.