Open Wound of the Knee

First aid for an open knee wound

1. Wash your hands and put on gloves if available.
2. Stop the bleeding. Press a clean cloth or gauze firmly on the wound for 5 to 10 minutes without lifting to check. Raise the leg on a pillow or chair.
3. Clean the wound. Rinse under cool running water for several minutes. Wash the skin around it with soap, keeping soap out of the wound if you can. Pick out loose grit with tweezers cleaned with alcohol. Do not use hydrogen peroxide or iodine directly in the wound, because they damage healing tissue.
4. Protect it. Apply a thin layer of petroleum jelly to keep it moist, then a nonstick pad and a bandage or a large adhesive dressing designed for joints. A figure-of-eight wrap stays on a bending knee better.
5. Change the dressing daily, or sooner if it gets wet or dirty.
6. Ease pain with acetaminophen (paracetamol) or ibuprofen, following the label dose.

Types of knee wound

Why knee wounds are different

• Constant movement: every step and bend pulls on a wound over the front of the knee. Cuts across the knee gape more and may reopen, so they are more likely to need stitches and benefit from limited bending for the first days.
• Thin skin over the kneecap: there is little fat between the skin and the kneecap, so a deep cut can reach the bone or the joint quickly.
• The prepatellar bursa: a small fluid sac sits between skin and kneecap. A cut or puncture can infect it, causing a hot, swollen, tender lump over the kneecap (prepatellar bursitis).
• The joint itself: a wound that enters the knee joint (traumatic arthrotomy) can introduce bacteria and cause septic arthritis, which can destroy cartilage within days. Doctors may inject sterile fluid into the joint to see if it leaks from the wound.

When an open knee wound needs a doctor

Get the wound assessed the same day if it:

• gapes open or the edges do not come together easily
• is deeper than about 6 mm (1/4 inch), or you can see fat, muscle, tendon or bone
• is longer than about 1 cm (1/2 inch) across the front of the knee
• was caused by something dirty, rusty, or by a bite
• has embedded debris
• happened in someone with diabetes, poor circulation or a weakened immune system

Wounds are best closed within about 6 to 8 hours, and up to 12 to 24 hours for clean wounds in well-supplied areas. After that, the infection risk of closing them rises.

Tetanus

You need a tetanus booster if the wound is dirty and your last dose was more than 5 years ago, or if the wound is clean and your last dose was more than 10 years ago. People never fully vaccinated may also need tetanus immune globulin.

Medical treatment

A clinician will check nerves, blood flow and knee movement, then numb and clean the wound thoroughly. Options include skin glue or adhesive strips for small, low-tension cuts, and stitches or staples for gaping ones. An X-ray looks for fractures or glass. Deep wounds near the joint may need a joint injection test, CT scan, or an operation to wash out the joint. Antibiotics are given for bites, heavily contaminated wounds and joint involvement.

Stitches over the knee usually stay in for 10 to 14 days, longer than on most body areas, because of the tension. A knee brace may limit bending for the first week.

Open knee wound healing

• Days 1 to 3: some swelling, pinkness at the edges and clear or slightly yellow fluid are normal.
• Days 3 to 14: new pink tissue fills in. A scab or moist healing layer forms.
• 2 to 6 weeks: the wound closes and strengthens. Kneeling may be tender for weeks.
• Up to 12 months: the scar matures and fades.

Help it heal:

• Keep it moist and covered. Moist wounds heal faster and scar less than dry scabs.
• Avoid kneeling and deep bending for the first 1 to 2 weeks.
• Do not soak it in baths, pools or hot tubs until it is closed.
• Once healed, protect it from the sun for a year and massage the scar with moisturizer.

Signs of infection

Watch for increasing pain after the first 2 days, spreading redness, warmth, swelling, thick yellow or green pus, a bad smell, red streaks up the thigh, or fever. See infected open wounds. A hot, swollen knee that hurts to bend may mean the joint or bursa is infected.

Frequently asked questions

How long does an open knee wound take to heal?

A shallow graze usually heals in 1 to 2 weeks. A stitched cut needs 10 to 14 days before stitches come out and several weeks to regain strength. Deeper wounds can take 4 to 6 weeks or longer, because constant bending of the knee slows healing.

Does a cut on my knee need stitches?

It likely needs stitches if it gapes, is deeper than about a quarter inch, shows fat or deeper tissue, keeps bleeding after 10 minutes of pressure, or is longer than about half an inch across the front of the knee. Get it checked within a few hours.

Should I keep a knee wound covered or let it air out?

Keep it covered. A moist, covered wound heals faster, hurts less and scars less than one left to dry out. Use petroleum jelly and a nonstick dressing, and change it daily or when wet or dirty.

Why does my knee wound keep reopening?

Bending stretches the healing skin over the kneecap. Limit deep bending and kneeling for the first 1 to 2 weeks, keep the area moist, and use a flexible joint dressing. If it keeps splitting or shows signs of infection, see a clinician.

What does an infected knee wound look like?

An infected wound becomes more painful, red, swollen and warm after the first couple of days, and may leak pus or smell bad. Red streaks or fever mean it is spreading. A hot, swollen knee joint that is painful to move needs urgent care.