Swelling after a total knee replacement (TKR) is an expected part of the healing process. This surgical procedure causes trauma to the joint, and the body’s natural response is to generate swelling, or edema, in the surrounding tissues. While some degree of swelling is normal, patients must monitor its severity and duration throughout their recovery.
The Biological Basis of Post-Surgical Swelling
Swelling is the physical manifestation of the body’s inflammatory response to injury. The surgery requires cutting through skin, muscle, and bone, causing tissue trauma and disrupting blood vessels. In response, the body floods the surgical site with fluid, including blood plasma and immune cells, to initiate the repair process. This influx of fluid into the tissue spaces causes the knee and surrounding area to become visibly swollen.
The lymphatic system, which normally drains excess fluid, is temporarily overwhelmed and less efficient due to the surgical manipulation. This insufficient drainage contributes to the buildup of protein-rich fluid in the leg, extending the duration of the swelling. The use of a tourniquet during the procedure, which controls bleeding, can also contribute to the inflammatory reaction and subsequent fluid accumulation.
The Expected Timeline for Swelling Resolution
The severity of the swelling changes significantly across the recovery period, following a predictable pattern. The acute phase, spanning the first two to four weeks following surgery, is when swelling is most pronounced. The knee and lower leg often feel tight and warm, which is a normal sign of the body’s peak inflammatory response.
During the sub-acute phase, typically lasting from weeks four to twelve, the swelling should gradually decrease. It is common for the edema to fluctuate throughout the day, often appearing worse in the evenings or after physical activity. This fluctuation is normal and indicates the body is managing fluid balance while activity levels increase.
Long-term resolution can take several months, with minor residual swelling potentially persisting for three to six months. Some patients may notice mild, intermittent puffiness up to a year after surgery, especially after strenuous activity or prolonged standing. The goal is a progressive reduction in edema over time.
Actionable Steps for Swelling Management
Patients can actively manage and reduce normal post-operative swelling through consistent application of simple techniques. The RICE method—Rest, Ice, Compression, and Elevation—remains the foundation of effective edema control. Applying ice packs to the knee for 15 to 20 minutes several times a day helps constrict blood vessels, reducing fluid flow to the area and providing pain relief.
Elevation is a highly effective technique that uses gravity to assist fluid drainage. For maximum effectiveness, the entire leg must be positioned so the ankle is raised above the level of the heart. Compression stockings or bandages, when used as prescribed, help prevent fluid from pooling in the lower leg and improve circulation.
Maintaining prescribed movement and physical therapy is also beneficial, as gentle muscle contraction helps pump fluid out of the tissues. Simple exercises like ankle pumps aid fluid circulation and help prevent blood clots. Non-steroidal anti-inflammatory drugs (NSAIDs), if approved by the surgeon, can help moderate the overall inflammatory response, which indirectly reduces swelling.
Recognizing Signs of Excessive or Dangerous Swelling
Signs of Infection and Excessive Swelling
While some swelling is expected, it is important to distinguish normal recovery from potentially dangerous complications that require immediate medical attention. Swelling that suddenly and severely increases, especially several weeks into recovery when it should be subsiding, is a warning sign. The normal warmth around the knee should not progress to intense, unrelenting heat accompanied by redness or a fever over 100.4°F (38°C), as these symptoms may indicate an infection.
Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE)
A separate concern is Deep Vein Thrombosis (DVT), a blood clot that forms deep in the leg veins. Signs of a DVT include sudden, severe swelling and tenderness, particularly in the calf or ankle, that is significantly worse in the operated leg compared to the non-operated leg. New or worsening pain in the calf that feels like an intense cramp, especially when walking or flexing the foot, should be reported immediately. Furthermore, if the swelling is accompanied by shortness of breath or chest pain, this could signal a life-threatening pulmonary embolism and requires emergency care.