Anterior cruciate ligament (ACL) surgery is a common procedure performed to repair a torn ligament in the knee. Patients frequently experience post-operative swelling, which is a natural part of the body’s healing process. Understanding this swelling is important for managing expectations and facilitating recovery.
The Swelling Timeline
Swelling after ACL surgery typically follows a predictable timeline. The most significant swelling usually occurs within the first few days, peaking around 2-3 days post-procedure. During this immediate phase, rest, ice, compression, and elevation help manage discomfort and inflammation.
Over the subsequent weeks, swelling begins to subside. By one to two weeks, pain and swelling are more controlled, and patients work on regaining full knee extension. Most patients experience a noticeable improvement in swelling, strength, and overall function between two to six months post-surgery.
While significant swelling diminishes within the first few months, some minor or residual swelling can persist for a longer period. Some swelling can remain for up to a year as part of the ongoing healing process. Factors influencing this duration include adherence to rehabilitation protocols, the type of graft used, and individual healing rates.
Understanding Swelling’s Origins
Post-ACL surgery swelling is a physiological response to the surgical intervention. The procedure involves cutting into tissues and replacing the damaged ligament, traumatizing the knee. This trauma triggers the body’s natural inflammatory response, directing immune cells and fluid to the surgical site to initiate healing.
Internal bleeding also contributes to fluid accumulation within the joint space. This fluid, combined with the inflammatory exudate, causes the visible swelling around the knee. While this process is a normal part of recovery, excessive fluid accumulation can impede knee function and delay rehabilitation progress.
Strategies for Swelling Reduction
Managing swelling is a practical step for smoother recovery. The RICE protocol—Rest, Ice, Compression, and Elevation—is recommended for this purpose. Resting the knee helps prevent further aggravation and allows the body to focus on healing.
Applying ice to the knee for 15-20 minutes, several times a day, helps reduce blood flow and inflammation. Compression provides support and helps prevent excess fluid accumulation. Elevating the leg above heart level facilitates fluid drainage from the joint area, reducing inflammation. Adherence to prescribed physical therapy exercises and gentle movement supports fluid circulation and overall healing.
Recognizing Concerning Swelling
While some swelling is expected, certain signs indicate a complication requiring medical attention. Swelling that does not improve with standard management or worsens after an initial reduction is a concern. This includes significant swelling that persists for weeks or months beyond the typical recovery period.
Other warning signs include intense pain that increases instead of decreasing, or increased warmth and redness around the surgical site. A fever, pus, or any unusual discharge from the incision prompt immediate evaluation by a healthcare professional. These symptoms are not typical for normal healing and may signal issues such as infection, blood clots, or other complications.