Anterior cruciate ligament (ACL) tearsare a common knee injury that often requires surgery to reconstruct the torn ligament. AlthoughACL reconstruction surgerieshave an 80% to 90% success rate,some patients may struggle with the decision to have it because of the complications that may follow.
Learn about some of the complications of ACL surgery and what you can do to ensure the best possible outcome if you experience them.
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Anterior Knee Pain
The most common complication of ACL surgery ispain around the kneecap. This complication is more likely in patients who have surgery performed with a patellar tendongraft, as these patients have bone removed from the kneecap as part of the procedure.
These patients can even have complications such aspatellar fractureandpatellar tendon tear, although these are very uncommon. However, patients having hamstring grafts or donor grafts can also have symptoms of anterior knee pain.
Anterior knee pain is thought to result from altered joint mechanics and can often be overcome with physical therapy. It’s important for athletes to adhere topostoperative rehab protocolsto ensure their knee mechanics improve.
Stiffness (Arthrofibrosis)
Stiffness in the knee joint is common after ACL surgery. Fortunately, most patients with stiffness can address this complication with aggressive rehabilitation.
However, in some cases, aball of scar tissueforms in the front of the knee even despite rehabilitation, and it can cause an inability to fully straighten the knee. This ball of scar tissue is known as a cyclops lesion, andarthroscopic surgeryis often needed to clean out the scar tissue.
The most critical step to avoid stiffness is to get the knee moving quickly after ACL surgery through rehabilitation exercises. In the past, doctors used specialized machines to bend the knee, calledCPM machines. However, these machines have not been shown to lead to long-term improvement.
If stiffness is slow to improve after ACL surgery and rehabilitation, research shows that arthroscopic surgery to remove scar tissue in the knee from the injury is generally effective in increasing mobility.
Instability
As the ACL is a major stabilizer of the knee, an ACL tear can cause the knee to be unstable. But even after reconstruction surgery, instability of the knee may still be an issue. Typically, this happens due to a surgical error or an undiscovered injury that occurred in or around the knee at the time of the ACL tear.
However, in some cases, post-surgical instability is present even after successful surgery and rehabilitation. Doctors and researchers are still finding the answers to why this may occur, but current research has suggested some possible explanations.
One study that followed up with 131 patients with knee instability after ACL reconstruction surgery found that either an accompanying grade 2medial collateral ligament (MCL) injuryor a delay in surgery for more than 12 weeks may be risk factors.
A sensation of theknee giving outis a common complaint of those dealing with knee instability.
However, studies are revealing possible ways to prevent and improve instability after reconstruction surgery.
For example, clinical studies have shown that some surgical methods, such as using two smaller grafts (double-bundle reconstruction) to reconstruct the ACL instead of one (single-bundle reconstruction), may decrease the chance of instability after surgery.And in one case study, an ACL revision surgery improved stability in a patient who had instability after a successful ACL procedure.
Graft Stretching
Poor surgical technique is a common cause of graft stretching, and ACL revision surgery is often needed.In ACL revision surgery, other parts of the knee, such as the meniscus, may need to be repaired in addition to replacing the prior graft.
Ganglion Cyst Formation
A rare complication from ACL reconstruction surgery is the formation of acystwithin or around the graft. These cysts are usually harmless and can be routinely removed, but can sometimes cause symptoms like:
Although the causes of these cysts aren’t clear, studies suggest that bodily reactions to specific surgical screws and the incorrect placement of a graft may be possible factors.
Growth Plate Injury
For adolescent patients, it’s possible that the growth plates of the knee can be damaged during ACL reconstruction surgery, which can lead to bone growth problems. Because of the risk, some doctors may elect to wait until the child grows older to perform the surgery.
However, methods are emerging that lessen the risk for growth plate injury, such as using a retractable drill to bore smaller holes for the placement of the graft.
Bleeding
Bleeding at the incision site of an ACL surgery is common but can be a concern if the blood is excessive enough that it soaks through wound dressings and does not stop after pressure is applied to the area.
Disease Transmission
Infection is a rare complication but can be serious when it occurs. When the infection is inside the knee joint, there is a concern about theACL graft becoming infected. If the infection is serious and does not get better with antibiotics, the graft may need to be surgically cleaned or removed to eliminate the infection.
To prevent infection, surgeons typically follow specific protocols for an ACL surgery, such as using new and sterilized surgical equipment for each procedure and ensuring that the patient receiving surgery is properly covered.
Blood Clots
Before ACL surgery, a doctor may prescribe blood thinners for those who have a family history of blood clots or who have conditions such as diabetes and obesity that make them more susceptible to blood clots. Other methods of prevention include:
Re-Rupture of the ACL Graft
Repeat rupture of the ACL graft is uncommon but sometimes occurs. Whenever there is a re-rupture of the graft, a surgeon should carefully assess for possible technical failures of the first surgery.
Possible problems that can lead to the re-tear of the ACL include suboptimal positioning of the graft, improper tension on the graft, or failure of the fixation of the graft.
ACL graftsare very strong. In fact, autograft tissue (tissue from one’s own patellar tendon or hamstring tendon) is stronger than the ACL. Allograft tissue (donor tissue), on the other hand, is not as strong, and re-tear rates are known to be higher with this type of graft. That is whycompetitive athletesoften choose to use their own tissue, even though rehab may be more difficult.
18 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Dean RS, LaPrade RF.ACL and posterolateral corner injuries.Curr Rev Musculoskelet Med. 2020;13(1):123-132. doi: 10.1007/s12178-019-09581-3Marques FDS, Barbosa PHB, Alves PR, et al.Anterior knee pain after anterior cruciate ligament reconstruction.Orthop J Sports Med. 2020;8(10):2325967120961082. doi:10.1177/2325967120961082Mcgrory BJ, Weber KL, Jevsevar DS, Sevarino K.Surgical management of osteoarthritis of the knee: Evidence-based guideline.J Am Acad Orthop Surg. 2016;24(8):e87-93. doi:10.5435/JAAOS-D-16-00159Stiefel EC, McIntyre L.Arthroscopic lysis of adhesions for treatment of post-traumatic arthrofibrosis of the knee joint.Arthrosc Tech. 2017;6(4):e939-e944. doi:10.1016/j.eats.2017.03.001Ahn JH, Lee SH.Risk factors for knee instability after anterior cruciate ligament reconstruction.Knee Surg Sports Traumatol Arthrosc. 2016;24(9):2936-2942. doi: 10.1007/s00167-015-3568-xFerretti A, Monaco E, Vadalà A.Rotatory instability of the knee after ACL tear and reconstruction.J Orthop Traumatol. 2014;15(2):75-79. doi:10.1007/s10195-013-0254-yHelito CP, Saithna A, Bonadio MB, et al.Anterolateral ligament reconstruction: a possible option in the therapeutic arsenal for persistent rotatory instability after ACL reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(1):232596711775134. doi: 10.1177/2325967117751348Wilde J, Bedi A, Altchek DW.Revision anterior cruciate ligament reconstruction.Sports Health. 2014;6(6):504-518. doi:10.1177/1941738113500910Joshi YV, Bhaskar D, Phaltankar PM, Charalambous CP.Tibial tunnel cyst formation after anterior cruciate ligament reconstruction using a non-bioabsorbable interference screw.Knee Surg Relat Res. 2015;27(4):269-273. doi:10.5792/ksrr.2015.27.4.269American Academy of Orthopaedic Surgeons.ACL injury: does it require surgery?John Hopkins Medicine.Sparing the growth plate in ACL reconstruction.MedlinePlus.ACL reconstruction - discharge.Palazzolo A, Rosso F, Bonasia DE, Saccia F, Rossi R.Uncommon complications after anterior cruciate ligament reconstruction.Joints. 2018;6(3):188-203. doi:10.1055/s-0038-1675799Gobbi A, Karnatzikos G, Chaurasia S, Abhishek M, Bulgherhoni E, Lane J.Postoperative infection after anterior cruciate ligament reconstruction.Sports Health. 2016;8(2):187-189. doi:10.1177/1941738115618638Kim HJ, Lee HJ, Lee JC, Min SG, Kyung HS.Evaluation of infection after anterior cruciate ligament reconstruction during a short period.Knee Surg Relat Res. 2017;29(1):45–51. doi:10.5792/ksrr.16.019Janssen RP, Reijman M, Janssen DM, Mourik JB.Arterial complications, venous thromboembolism and deep venous thrombosis prophylaxis after anterior cruciate ligament reconstruction: A systematic review.World J Orthop. 2016;7(9):604-617. doi:10.5312/wjo.v7.i9.604Bokshan SL, DeFroda SF, Panarello NM, Owens BD.Risk factors for deep vein thrombosis or pulmonary embolus following anterior cruciate ligament reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(6):232596711878132. doi:10.1177/2325967118781328Keller RA, Moutzouros V, Dines JS, Bush-Joseph CA, Limpisvasti O.Deep venous thrombosis prophylaxis in anterior cruciate ligament reconstructive surgery: what is the current state of practice?Sports Health. 2018;10(2):156-159. doi:10.1177/1941738117730576
18 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Dean RS, LaPrade RF.ACL and posterolateral corner injuries.Curr Rev Musculoskelet Med. 2020;13(1):123-132. doi: 10.1007/s12178-019-09581-3Marques FDS, Barbosa PHB, Alves PR, et al.Anterior knee pain after anterior cruciate ligament reconstruction.Orthop J Sports Med. 2020;8(10):2325967120961082. doi:10.1177/2325967120961082Mcgrory BJ, Weber KL, Jevsevar DS, Sevarino K.Surgical management of osteoarthritis of the knee: Evidence-based guideline.J Am Acad Orthop Surg. 2016;24(8):e87-93. doi:10.5435/JAAOS-D-16-00159Stiefel EC, McIntyre L.Arthroscopic lysis of adhesions for treatment of post-traumatic arthrofibrosis of the knee joint.Arthrosc Tech. 2017;6(4):e939-e944. doi:10.1016/j.eats.2017.03.001Ahn JH, Lee SH.Risk factors for knee instability after anterior cruciate ligament reconstruction.Knee Surg Sports Traumatol Arthrosc. 2016;24(9):2936-2942. doi: 10.1007/s00167-015-3568-xFerretti A, Monaco E, Vadalà A.Rotatory instability of the knee after ACL tear and reconstruction.J Orthop Traumatol. 2014;15(2):75-79. doi:10.1007/s10195-013-0254-yHelito CP, Saithna A, Bonadio MB, et al.Anterolateral ligament reconstruction: a possible option in the therapeutic arsenal for persistent rotatory instability after ACL reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(1):232596711775134. doi: 10.1177/2325967117751348Wilde J, Bedi A, Altchek DW.Revision anterior cruciate ligament reconstruction.Sports Health. 2014;6(6):504-518. doi:10.1177/1941738113500910Joshi YV, Bhaskar D, Phaltankar PM, Charalambous CP.Tibial tunnel cyst formation after anterior cruciate ligament reconstruction using a non-bioabsorbable interference screw.Knee Surg Relat Res. 2015;27(4):269-273. doi:10.5792/ksrr.2015.27.4.269American Academy of Orthopaedic Surgeons.ACL injury: does it require surgery?John Hopkins Medicine.Sparing the growth plate in ACL reconstruction.MedlinePlus.ACL reconstruction - discharge.Palazzolo A, Rosso F, Bonasia DE, Saccia F, Rossi R.Uncommon complications after anterior cruciate ligament reconstruction.Joints. 2018;6(3):188-203. doi:10.1055/s-0038-1675799Gobbi A, Karnatzikos G, Chaurasia S, Abhishek M, Bulgherhoni E, Lane J.Postoperative infection after anterior cruciate ligament reconstruction.Sports Health. 2016;8(2):187-189. doi:10.1177/1941738115618638Kim HJ, Lee HJ, Lee JC, Min SG, Kyung HS.Evaluation of infection after anterior cruciate ligament reconstruction during a short period.Knee Surg Relat Res. 2017;29(1):45–51. doi:10.5792/ksrr.16.019Janssen RP, Reijman M, Janssen DM, Mourik JB.Arterial complications, venous thromboembolism and deep venous thrombosis prophylaxis after anterior cruciate ligament reconstruction: A systematic review.World J Orthop. 2016;7(9):604-617. doi:10.5312/wjo.v7.i9.604Bokshan SL, DeFroda SF, Panarello NM, Owens BD.Risk factors for deep vein thrombosis or pulmonary embolus following anterior cruciate ligament reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(6):232596711878132. doi:10.1177/2325967118781328Keller RA, Moutzouros V, Dines JS, Bush-Joseph CA, Limpisvasti O.Deep venous thrombosis prophylaxis in anterior cruciate ligament reconstructive surgery: what is the current state of practice?Sports Health. 2018;10(2):156-159. doi:10.1177/1941738117730576
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Dean RS, LaPrade RF.ACL and posterolateral corner injuries.Curr Rev Musculoskelet Med. 2020;13(1):123-132. doi: 10.1007/s12178-019-09581-3Marques FDS, Barbosa PHB, Alves PR, et al.Anterior knee pain after anterior cruciate ligament reconstruction.Orthop J Sports Med. 2020;8(10):2325967120961082. doi:10.1177/2325967120961082Mcgrory BJ, Weber KL, Jevsevar DS, Sevarino K.Surgical management of osteoarthritis of the knee: Evidence-based guideline.J Am Acad Orthop Surg. 2016;24(8):e87-93. doi:10.5435/JAAOS-D-16-00159Stiefel EC, McIntyre L.Arthroscopic lysis of adhesions for treatment of post-traumatic arthrofibrosis of the knee joint.Arthrosc Tech. 2017;6(4):e939-e944. doi:10.1016/j.eats.2017.03.001Ahn JH, Lee SH.Risk factors for knee instability after anterior cruciate ligament reconstruction.Knee Surg Sports Traumatol Arthrosc. 2016;24(9):2936-2942. doi: 10.1007/s00167-015-3568-xFerretti A, Monaco E, Vadalà A.Rotatory instability of the knee after ACL tear and reconstruction.J Orthop Traumatol. 2014;15(2):75-79. doi:10.1007/s10195-013-0254-yHelito CP, Saithna A, Bonadio MB, et al.Anterolateral ligament reconstruction: a possible option in the therapeutic arsenal for persistent rotatory instability after ACL reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(1):232596711775134. doi: 10.1177/2325967117751348Wilde J, Bedi A, Altchek DW.Revision anterior cruciate ligament reconstruction.Sports Health. 2014;6(6):504-518. doi:10.1177/1941738113500910Joshi YV, Bhaskar D, Phaltankar PM, Charalambous CP.Tibial tunnel cyst formation after anterior cruciate ligament reconstruction using a non-bioabsorbable interference screw.Knee Surg Relat Res. 2015;27(4):269-273. doi:10.5792/ksrr.2015.27.4.269American Academy of Orthopaedic Surgeons.ACL injury: does it require surgery?John Hopkins Medicine.Sparing the growth plate in ACL reconstruction.MedlinePlus.ACL reconstruction - discharge.Palazzolo A, Rosso F, Bonasia DE, Saccia F, Rossi R.Uncommon complications after anterior cruciate ligament reconstruction.Joints. 2018;6(3):188-203. doi:10.1055/s-0038-1675799Gobbi A, Karnatzikos G, Chaurasia S, Abhishek M, Bulgherhoni E, Lane J.Postoperative infection after anterior cruciate ligament reconstruction.Sports Health. 2016;8(2):187-189. doi:10.1177/1941738115618638Kim HJ, Lee HJ, Lee JC, Min SG, Kyung HS.Evaluation of infection after anterior cruciate ligament reconstruction during a short period.Knee Surg Relat Res. 2017;29(1):45–51. doi:10.5792/ksrr.16.019Janssen RP, Reijman M, Janssen DM, Mourik JB.Arterial complications, venous thromboembolism and deep venous thrombosis prophylaxis after anterior cruciate ligament reconstruction: A systematic review.World J Orthop. 2016;7(9):604-617. doi:10.5312/wjo.v7.i9.604Bokshan SL, DeFroda SF, Panarello NM, Owens BD.Risk factors for deep vein thrombosis or pulmonary embolus following anterior cruciate ligament reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(6):232596711878132. doi:10.1177/2325967118781328Keller RA, Moutzouros V, Dines JS, Bush-Joseph CA, Limpisvasti O.Deep venous thrombosis prophylaxis in anterior cruciate ligament reconstructive surgery: what is the current state of practice?Sports Health. 2018;10(2):156-159. doi:10.1177/1941738117730576
Dean RS, LaPrade RF.ACL and posterolateral corner injuries.Curr Rev Musculoskelet Med. 2020;13(1):123-132. doi: 10.1007/s12178-019-09581-3
Marques FDS, Barbosa PHB, Alves PR, et al.Anterior knee pain after anterior cruciate ligament reconstruction.Orthop J Sports Med. 2020;8(10):2325967120961082. doi:10.1177/2325967120961082
Mcgrory BJ, Weber KL, Jevsevar DS, Sevarino K.Surgical management of osteoarthritis of the knee: Evidence-based guideline.J Am Acad Orthop Surg. 2016;24(8):e87-93. doi:10.5435/JAAOS-D-16-00159
Stiefel EC, McIntyre L.Arthroscopic lysis of adhesions for treatment of post-traumatic arthrofibrosis of the knee joint.Arthrosc Tech. 2017;6(4):e939-e944. doi:10.1016/j.eats.2017.03.001
Ahn JH, Lee SH.Risk factors for knee instability after anterior cruciate ligament reconstruction.Knee Surg Sports Traumatol Arthrosc. 2016;24(9):2936-2942. doi: 10.1007/s00167-015-3568-x
Ferretti A, Monaco E, Vadalà A.Rotatory instability of the knee after ACL tear and reconstruction.J Orthop Traumatol. 2014;15(2):75-79. doi:10.1007/s10195-013-0254-y
Helito CP, Saithna A, Bonadio MB, et al.Anterolateral ligament reconstruction: a possible option in the therapeutic arsenal for persistent rotatory instability after ACL reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(1):232596711775134. doi: 10.1177/2325967117751348
Wilde J, Bedi A, Altchek DW.Revision anterior cruciate ligament reconstruction.Sports Health. 2014;6(6):504-518. doi:10.1177/1941738113500910
Joshi YV, Bhaskar D, Phaltankar PM, Charalambous CP.Tibial tunnel cyst formation after anterior cruciate ligament reconstruction using a non-bioabsorbable interference screw.Knee Surg Relat Res. 2015;27(4):269-273. doi:10.5792/ksrr.2015.27.4.269
American Academy of Orthopaedic Surgeons.ACL injury: does it require surgery?
John Hopkins Medicine.Sparing the growth plate in ACL reconstruction.
MedlinePlus.ACL reconstruction - discharge.
Palazzolo A, Rosso F, Bonasia DE, Saccia F, Rossi R.Uncommon complications after anterior cruciate ligament reconstruction.Joints. 2018;6(3):188-203. doi:10.1055/s-0038-1675799
Gobbi A, Karnatzikos G, Chaurasia S, Abhishek M, Bulgherhoni E, Lane J.Postoperative infection after anterior cruciate ligament reconstruction.Sports Health. 2016;8(2):187-189. doi:10.1177/1941738115618638
Kim HJ, Lee HJ, Lee JC, Min SG, Kyung HS.Evaluation of infection after anterior cruciate ligament reconstruction during a short period.Knee Surg Relat Res. 2017;29(1):45–51. doi:10.5792/ksrr.16.019
Janssen RP, Reijman M, Janssen DM, Mourik JB.Arterial complications, venous thromboembolism and deep venous thrombosis prophylaxis after anterior cruciate ligament reconstruction: A systematic review.World J Orthop. 2016;7(9):604-617. doi:10.5312/wjo.v7.i9.604
Bokshan SL, DeFroda SF, Panarello NM, Owens BD.Risk factors for deep vein thrombosis or pulmonary embolus following anterior cruciate ligament reconstruction.Orthopaedic Journal of Sports Medicine. 2018;6(6):232596711878132. doi:10.1177/2325967118781328
Keller RA, Moutzouros V, Dines JS, Bush-Joseph CA, Limpisvasti O.Deep venous thrombosis prophylaxis in anterior cruciate ligament reconstructive surgery: what is the current state of practice?Sports Health. 2018;10(2):156-159. doi:10.1177/1941738117730576
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