Swollen Ankle and Foot After Knee Replacement: Causes, DVT Warning Signs, and Proven Fixes

Swelling in the ankle and foot after total knee replacement surgery can leave patients confused and anxious. While some amount of swelling is a normal part of the healing process, persistent or worsening swelling—especially when accompanied by warmth, redness, or pain—could indicate something more serious, like a deep vein thrombosis (DVT).

This guide walks you through why your foot may swell after knee surgery, how to tell when swelling is normal or dangerous, and doctor-recommended steps to reduce swelling safely and effectively.

• Fluid accumulation from surgical trauma: After a knee replacement, your body responds with inflammation and increased blood flow to the area. This often causes fluid buildup not just in the knee, but in the lower leg, ankle, and foot.
• Gravity’s effect on circulation: Since your leg remains lower than your heart when sitting or standing, fluids naturally pool in the foot and ankle, especially in the early recovery stages.
• Lymphatic system overload: The surgical site may compromise normal lymphatic drainage, leading to temporary swelling beyond the knee.
• Reduced muscle activity: Limited walking or exercise reduces calf muscle contractions, which play a key role in pumping blood and fluids back toward the heart.

Some post-operative swelling is expected in the first 2 to 4 weeks after knee replacement. You might notice:

• Puffiness in the foot and ankle after standing or walking
• Swelling that decreases overnight or after elevation
• Mild discoloration that fades with rest

However, red flags for something more serious include:

• Swelling that is one-sided and rapidly worsening
• Persistent redness or warmth in the calf or foot
• Painful tenderness, especially in the back of the calf
• A visibly enlarged vein or hard knot in the leg
• Shortness of breath or chest pain (in severe cases)

These could be signs of deep vein thrombosis—a potentially life-threatening condition.

A deep vein thrombosis is a blood clot that forms in a deep vein, most commonly in the leg. Knee replacement surgery increases the risk of DVT due to:

• Reduced mobility during the early healing phase
• Blood vessel injury during surgery
• Increased clotting tendencies from inflammation

If untreated, a DVT can travel to the lungs and cause a pulmonary embolism, which can be fatal.

• A sudden increase in leg pain or tightness
• Warmth or heat over a vein
• Skin that appears red or discolored
• A heavy or achy sensation in one leg
• Unilateral swelling (only one foot or ankle affected)

If you experience any of these symptoms, seek emergency medical attention.

Not all swelling indicates DVT. Other common causes include:

1. Seroma or Hematoma
   • A collection of fluid or blood under the skin near the surgical site can cause swelling to travel downward.
2. Infection
   • Though rare, infection near the surgical site can present with swelling, pain, and fever.
3. Muscle or ligament strain
   • Overuse or improper movement during early rehabilitation can cause inflammation.
4. Nerve irritation
   • Swelling can also result from irritation or compression of nerves around the knee or lower leg.

1. Elevation—But With Proper Technique
   • Elevate your leg above heart level several times per day. Prop your entire leg on 2–3 pillows, not just the foot.
   • Avoid letting the knee hang unsupported or bending the hip too much during elevation.
2. Use Cold Packs Wisely
   • Apply cold compresses to the ankle and lower leg for 15-20 minutes at a time.
   • Do not place ice directly on the skin—use a cloth barrier to prevent frostbite.
3. Compression Therapy
   • Compression socks or wraps may help, but always consult your surgeon first.
   • Too much compression too soon can interfere with blood flow or incision healing.
4. Gentle Ankle Pumps and Foot Exercises
   • Point and flex your toes every hour while awake.
   • Rotate your ankles in circles to help reduce fluid retention and improve circulation.
5. Hydration and Nutrition
   • Drinking adequate water flushes excess sodium and reduces fluid retention.
   • Avoid high-salt and processed foods that may worsen swelling.
6. Physical Therapy
   • Follow your physical therapist’s advice closely. Movement aids circulation, but overexertion can make swelling worse.
   • Focus on building strength and flexibility gradually.
7. Don’t Skip Medications
   • If your surgeon prescribed blood thinners, take them exactly as directed.
   • Medications like aspirin, enoxaparin, or rivaroxaban are often used to prevent blood clots.

• Do not sit or stand for long periods without moving—set a timer to change position every 30–60 minutes.
• Avoid massaging the swollen leg, especially if there’s pain or redness, as this may dislodge a clot.
• Never skip your follow-up visits. Post-surgical complications may show up even weeks later.
• Do not self-diagnose or self-treat persistent swelling—always consult your healthcare provider.

If you notice any of the following, it’s time to call your surgical team or go to the emergency room:

• Swelling that rapidly worsens in one leg
• Redness or streaking along the leg
• Pain in the calf that worsens with walking or foot flexion
• Fever over 100.4°F (38°C)
• Sudden shortness of breath or chest pain

Foot and ankle swelling after total knee replacement is often a normal part of healing, especially in the first month. However, knowing the difference between expected swelling and DVT warning signs can be lifesaving.

Be proactive—elevate, move safely, follow rehab instructions, and always reach out to your provider if something feels off. With early detection and smart recovery strategies, most patients make a full and healthy recovery.