Introduction: Understanding Complications After ACL Surgery

Anterior cruciate ligament (ACL) surgery is essential for restoring stability and function to the knee following injury. For many, this operation promises improved movement, reduced pain, and a return to everyday activities. While most recover smoothly, it’s important to be aware that complications can sometimes occur. Recent studies remind us that “post-operative complications remain a significant concern that can adversely affect patient outcomes” (Gharpinde et al., 2024). This guide is designed to help patients and their carers recognise warning signs after ACL surgery, so you know what to expect and when to seek help—making your recovery safer and more straightforward.

What to Expect: Normal Postoperative Pain and Swelling

After ACL surgery, it’s common to experience moderate pain and swelling around the knee. Bruising and some stiffness in the joint are also perfectly normal in the early days following the procedure. These symptoms usually peak within a few days and then gradually ease over several weeks. You should notice your pain and swelling steadily reducing, with your knee gradually becoming easier to move. To manage typical discomfort, it’s important to follow your surgeon’s advice closely—this often includes resting the leg, keeping it elevated, applying cold packs, and taking pain relief as prescribed. Understanding this typical healing pattern will help you recognise normal recovery and spot when something isn’t quite right.

Recognising Red Flag Symptoms: Warning Signs of Serious Complications

While some pain and swelling are to be expected, there are certain symptoms that should raise concern and prompt you to seek medical advice urgently. These include severe or worsening pain that doesn’t improve with medication, swelling that becomes excessive or increases rapidly, and redness or warmth around the surgical site. A persistent high temperature, sudden difficulty moving the knee, unusual fluid leaking from the wound, or any foul smell warrant immediate attention. Such signs may indicate an infection, blood clots, or problems with the graft itself. As highlighted in recent research, “no single fixation method is best for all patients. The choice depends on the graft type, patient condition, and surgeon preference” (Manaf et al., 2025). It’s also worth noting that some patients have higher risks; for example, “patients with ADHD who undergo ACL reconstruction are at increased risk of early revision surgery, wound complications, and hospital readmission” (Sasaki et al., 2025). Furthermore, complications can span a wide spectrum, including “infection, graft failure, and knee stiffness to less frequent but important issues like osteoarthritis and nerve injuries” (Gharpinde et al., 2024). It’s essential to differentiate these warning signs from normal recovery symptoms. For instance, while some swelling is usual, sharp pain with redness and heat is not and must be investigated promptly.

When to Seek Immediate Medical Attention and What to Do Next

If you notice any of these red flag symptoms, seeking medical help immediately is crucial. Contact your surgeon or healthcare provider, clearly explaining your symptoms, when they started, and how they have changed. Keeping a symptom diary—recording the time, severity, and any other details—can be very helpful for your medical team. Certain symptoms like chest pain, sudden shortness of breath, or fainting require emergency care as they might signal serious problems such as pulmonary embolism. Acting quickly and communicating clearly with your care team are vital steps to managing complications effectively and protecting your health.

The Role of Specialist Care and Support During Recovery

Specialist care plays a pivotal role in spotting and managing complications early. Orthopaedic surgeons and their teams bring valuable expertise and dedicated support throughout your recovery journey. Professor Paul Lee, a respected expert in the field, holds roles as Cartilage Expert, Regional Surgical Ambassador, and Royal College of Surgeons of Edinburgh Advisor, exemplifying the high level of care patients can expect. MSK Doctors provide a professional, supportive environment that encourages tailored rehabilitation focused on your unique needs. As research reminds us, “understanding the properties and limitations of each technique is key to optimising ACL reconstruction results” (Manaf et al., 2025). A collaborative, multidisciplinary approach “can minimise risk, improve outcomes, and enhance quality of life for patients undergoing ACL reconstruction” (Gharpinde et al., 2024). In specific cases, such as patients with ADHD, “tailoring postoperative rehabilitation protocols helps reduce risks of complications” (Sasaki et al., 2025). By engaging actively with your healthcare team, you greatly increase your chances of a successful recovery.

Conclusion: Staying Vigilant for a Safer Recovery

Early recognition of complications after ACL surgery is key to a safe and effective recovery. Patients and carers should carefully monitor symptoms, follow medical advice, and communicate openly with their healthcare teams. Staying informed and involved empowers you to achieve the best possible outcome. Remember, being an active participant in your recovery is one of the most important steps you can take towards returning to full health.

References

• Gharpinde, M. R., Pundkar, A., Dhanwani, Y., Chandanwale, R., & Jaiswal, A. (2024). Navigating Post-operative Challenges: A Comprehensive Review of Complications Following Anterior Cruciate Ligament (ACL) Tear Surgery. Cureus. https://doi.org/10.7759/cureus.67768
• Manaf, F., Pawana, I. A., & Utomo, D. (2025). The Art of Fixation in ACL Surgery: A Comparative Review of Button, Screw, Pin, Staple, and Staple Anchor. Journal of Knee Surgery, 14(32s), Article 7972. https://doi.org/10.63682/jns.v14i32s.7972
• Sasaki, J., Fuller, S. I., Kocan, J., Yunke, A., Pavlesen, S., Del Prince, C., & Macfarlane, A. (2025). ADHD Is Associated With Increased Rates of Postoperative Complications and Revision Surgery After ACL Reconstruction. Sports Health. https://doi.org/10.1177/19417381251385585