Anterior Cruciate Ligament (ACL) reconstruction surgery, which replaces a torn ligament with a graft (autograft or allograft), commonly results in post-operative swelling. Understanding its timeline and influencing factors helps manage recovery expectations.
Typical Swelling Timeline
Swelling is a normal and expected response immediately following ACL surgery. The body’s inflammatory process sends fluid and immune cells to the surgical site to facilitate healing. This acute phase of swelling generally peaks within the first few days, often within the initial week after the operation. During this period, the knee may appear noticeably larger than normal.
After the initial peak, the swelling begins to subside gradually. Over the subsequent weeks and months, patients should observe a steady reduction in the size of their knee. While significant improvement is usually seen by one to two months post-surgery, some degree of swelling can persist for several weeks. Complete resolution of swelling can take several months, with minor swelling potentially lingering for up to six to nine months as the knee fully recovers and adapts.
What Affects Swelling Duration
Several factors can influence how long swelling lasts after ACL surgery. The type of graft used plays a role; autografts, which involve taking tissue from the patient’s own body (such as patellar tendon, hamstring tendon, or quadriceps tendon), can sometimes lead to more initial swelling due to an additional donor site wound. Allografts, derived from donor tissue, bypass this second wound, potentially reducing some aspects of immediate post-operative swelling, though they may have different healing characteristics.
The extent of the initial knee injury and any associated damage to other structures, such as the meniscus or other ligaments, can also impact swelling. More extensive injuries or additional procedures performed during surgery may result in a more pronounced and prolonged inflammatory response. Individual healing rates vary significantly among patients, with factors like overall health, age, and adherence to post-operative instructions contributing to how quickly the body resolves swelling. Over-activity or failing to follow rehabilitation guidelines can lead to increased inflammation and delayed swelling resolution.
Strategies for Swelling Reduction
Effective swelling management aids pain relief and facilitates rehabilitation. The RICE protocol (Rest, Ice, Compression, and Elevation) is a widely recommended approach.
Resting the knee prevents irritation and promotes healing. Applying ice for 15-20 minutes every few hours constricts blood vessels, reducing fluid and providing pain relief. Compression, with an elastic bandage or specialized garment, provides gentle pressure to minimize swelling and support the area. Elevating the leg above heart level, especially during rest, promotes fluid drainage away from the knee. Physical therapy exercises, as prescribed, also improve circulation and fluid drainage through gentle movement.
When to Contact Your Doctor
While some swelling is a normal part of ACL surgery recovery, certain signs can indicate a potential complication that requires medical attention. It is important to contact your doctor if you experience a sudden or significant increase in swelling that does not improve with rest, ice, and elevation. This could signal an issue such as a blood clot or internal bleeding.
Other warning signs include:
Severe pain that worsens or does not respond to prescribed medications.
Increased redness or warmth around the surgical site.
Any discharge or oozing from the incision.
A persistent fever above 100.4°F (38°C).
Numbness or tingling in the foot.
A feeling that the knee is unstable or “giving way.”