Swelling is an expected and normal reaction to the trauma of Anterior Cruciate Ligament (ACL) reconstruction surgery. The body’s inflammatory response sends fluid and immune cells to the surgical site, resulting in a buildup of fluid around the knee joint. Managing this post-surgical swelling efficiently is a primary goal in early recovery, as excessive fluid can inhibit the quadriceps muscle, limit the knee’s range of motion, and increase pain. Controlling swelling is directly tied to the speed and success of subsequent rehabilitation phases.
Immediate Physical Interventions
Reducing post-operative swelling in the first few days relies heavily on elevation, cold therapy, and compression. Elevating the surgical leg uses gravity to encourage the return of excess fluid to the central circulation. The leg must be positioned so the knee and ankle are elevated above the level of the heart, typically requiring the foot to be raised approximately 12 inches higher than the chest.
It is essential to support the leg correctly during elevation by placing pillows or a specialized wedge under the calf and ankle, ensuring the knee remains fully straight. Avoid placing support directly behind the knee, as this can lead to a flexion contracture and complicate achieving full knee extension. Elevation should be performed several times a day, often for periods of 30 to 60 minutes, especially when the knee feels swollen or throbs.
Cold therapy, or cryotherapy, is a fundamental intervention, working to constrict blood vessels and slow the inflammatory response. Ice packs or dedicated cryo-cuff devices should be applied for 20 to 30 minutes at a time, typically every three to four hours while awake. To prevent skin injury, a thin layer of material must always be placed between the ice source and the skin.
Compression is used simultaneously with elevation and cold therapy to help prevent fluid from settling around the joint. This is achieved using elastic bandages, compression stockings, or specialized post-operative wraps that apply consistent pressure from the foot toward the thigh. The compression device should be snug enough to prevent fluid pooling but must not be so tight that it causes pain, numbness, or tingling in the foot.
Pharmacological Support for Inflammation
Systemic medications are frequently used to manage the inflammation and pain that contribute to post-operative swelling. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can effectively reduce swelling and pain by blocking the chemical pathways that cause inflammation. However, the use of NSAIDs immediately following ACL surgery requires careful consideration and must be approved by the surgical team.
Some surgeons may restrict the use of NSAIDs for a period, sometimes up to six weeks, due to concerns that these drugs could interfere with the healing process of the ligament graft or the bone tunnels. Acetaminophen, which manages pain but lacks anti-inflammatory properties, is often used as an alternative or alongside opioid pain medications to control discomfort in the initial recovery period.
Swelling Management Through Controlled Movement
Once approved by the surgeon or physical therapist, controlled movement shifts the focus from passive swelling reduction to actively circulating accumulated fluid out of the joint. The lymphatic system relies on muscle contractions to push fluid along its vessels, making gentle, active exercises an important component of swelling management.
Ankle pumps are one of the earliest and most recommended active exercises, involving pointing the foot up toward the head and then down away from it. This rhythmic contraction of the calf muscles acts as a “second heart,” effectively pumping blood and lymph fluid back toward the torso without placing stress on the healing knee joint. Patients are often instructed to perform sets of ankle pumps frequently to maintain circulation and prevent blood clots.
Gentle, approved range-of-motion (ROM) exercises, such as heel slides to work on knee bending, also facilitate fluid circulation by engaging the muscles around the knee. Additionally, a physical therapist may employ manual lymphatic drainage, which involves massage techniques to manually guide fluid away from the swollen area toward lymph nodes. The goal of these movements is to strike a balance: moving enough to activate fluid-draining mechanisms without over-stressing the healing tissues, which would cause increased swelling.
Recognizing Red Flags and When to Contact Your Doctor
While some swelling is normal, certain signs indicate a complication rather than typical post-operative recovery. These symptoms require immediate medical attention and should be reported to the surgical team without delay.
- A sudden, severe increase in swelling that does not improve with elevation and ice, or swelling that spreads significantly down the lower leg.
- Persistent pain that worsens instead of gradually improving, especially pain unmanageable with prescribed medication.
- Signs of potential infection, including a fever higher than 101°F (38.3°C), chills, or excessive warmth and redness around the incision site.
- Any drainage from the surgical wound that is profuse, foul-smelling, or changes from clear to a thick, yellow or green color.
- Symptoms suggestive of a Deep Vein Thrombosis (DVT), such as sharp, unusual pain, tenderness, or tightness in the calf muscle, along with warmth or discoloration below the knee.