What causes pain after ACL surgery? I’d like to go over a few common causes. I’ll also review a patient with chronic pain after ACL surgery as an example. Let’s dig in.
ACL Surgery 101
ACL surgery is also called “ACLR” (ACL reconstruction) and is an arthroscopic procedure whereby a torn tendon is removed surgically and then the ligament is replaced by a tendon graft (1). That tendon can be taken from the patient (oftentimes the hamstrings or the quadriceps tendon) or a cadaver graft can be used. To get the tendon to stay in place, the surgeon drills tunnels in the top femur bone and in the bottom tibia bone and then anchors the tendon in those tunnels.
The Damage Done by ACL Surgery
Most people believe that when they’re getting a body part replaced like an ACL that the doctor merely switches out the part like a new tire on a car. However, that’s not close to accurate. The surgery to replace the ACL will do predictable damage to the knee. This damage can lead to pain after ACL surgery.
For example, we know that the ACL reconstruction surgery itself acts as a second hit to the knee cartilage (2). Meaning the first cartilage damage event comes with the injury and the second comes after the doctor drills the tunnels to place the ACL graft. Meaning, based on recent research, the act of performing an ACL surgery may be further damaging the cartilage. This likely explains why, despite stabilizing the knee, ACL surgery doesn’t prevent or delay the onset of knee arthritis (4). Obviously, the early onset of knee arthritis could be one cause of pain after ACL surgery.
More Damage from ACL Surgery
ACL surgery can cause damage in many different parts of the knee. This damage can happen due to removing stem cells that the knee needs to stay healthy, damage to the ligaments that hold the meniscus in place, and damage to the knee tendons. These areas of surgery-induced damage can also cause pain after ACL surgery.
First is the fact that the knee has many natural healing stem cells located in the fat pad and around the ACL (3). These stem cells help to maintain the cartilage and other structures in the knee. These critical deposits of fat are oftentimes removed during ACL surgery because they’re simply in the way of the surgeon. This likely reduces the ability of the knee to heal and maintain itself in a healthy state.
The second issue is caused by the placement of one of the graft tunnels. This hole drilled in the tibia bone is often placed right through a ligament that holds the front of the two halves of the meniscus together (intermeniscal ligament). In my experience, when surgeons damage this ligament, the meniscus tends to become unstable and move out of the joint, getting rid of its shock-absorbing ability. This can also lead to the cartilage in this area being damaged and more pain after ACL surgery.
Finally, the tendons around the knee can get damaged by the other end of the same graft tunnel. Here the patient can be left with chronic inside knee pain. Let’s review one patient’s experience.
Chronic Inside Knee Pain After ACL Surgery
My patient this past week had an ACL reconstruction surgery years ago. Her ACL graft is mostly gone at this point, which is not uncommon. More importantly, she experiences deep pain right at the tibial tunnel site. That’s where they drilled the hole to create the tunnel to anchor the ACL graft. So she has pain after ACL surgery.
As the video above shows, the patient’s pes anserine tendon was destroyed by the surgeon’s drill. This is an important tendon of three thigh muscles (sartorius, gracilis and semitendinosus). This is like a guy rope system for the inside knee, so damaging this tendon will change how the knee works.
What can I do to help? Our plan is to use precise ultrasound guidance to inject her own bone marrow stem cells into the damaged area of the pes tendon. Hopefully, this will cause enough healing so that her pain after ACL surgery at this spot will go away.
Can You Avoid ACL Surgery?
We’ve been helping torn ACL ligaments heal by using a precise injection of the patient’s own stem cells for years (5,6). The video below explains how that’s one:
The upshot? Pain after ACL surgery is surprisingly common. I see it frequently in our clinic and the reasons why I see it are not surprising. In this patient, who had a hole drilled through her tendon, hopefully, we can help!
(1) Mahapatra P, Horriat S, Anand BS. Anterior cruciate ligament repair – past, present and future. J Exp Orthop. 2018;5(1):20. Published 2018 Jun 15. doi:10.1186/s40634-018-0136-6
(2) Lattermann C, Conley CE, Johnson DL, et al. Select Biomarkers on the Day of Anterior Cruciate Ligament Reconstruction Predict Poor Patient-Reported Outcomes at 2-Year Follow-Up: A Pilot Study. Biomed Res Int. 2018;2018:9387809. Published 2018 Jul 19. doi:10.1155/2018/9387809
(3) Zhong YC, Wang SC, Han YH, Wen Y. Recent Advance in Source, Property, Differentiation, and Applications of Infrapatellar Fat Pad Adipose-Derived Stem Cells. Stem Cells Int. 2020;2020:2560174. Published 2020 Mar 7. doi:10.1155/2020/2560174
(4) van Meer BL, Oei EH, Meuffels DE, et al. Degenerative Changes in the Knee 2 Years After Anterior Cruciate Ligament Rupture and Related Risk Factors: A Prospective Observational Follow-up Study. Am J Sports Med. 2016;44(6):1524‐1533. doi:10.1177/0363546516631936
(5) Centeno CJ, Pitts J, Al-Sayegh H, Freeman MD. Anterior cruciate ligament tears treated with percutaneous injection of autologous bone marrow nucleated cells: a case series. J Pain Res. 2015;8:437–447. https://www.ncbi.nlm.nih.gov/pubmed/26261424
(6) Centeno C, Markle J, Dodson E, et al. Symptomatic anterior cruciate ligament tears treated with percutaneous injection of autologous bone marrow concentrate and platelet products: a non-controlled registry study. J Transl Med. 2018;16(1):246. https://www.ncbi.nlm.nih.gov/pubmed/30176875