The Dreaded ACL Tear

Cue Boobie Miles in Friday Night Lights. If you’ve ever watched the movie, you know how haunting this scene is as the star player goes down, grabbing at his leg and screaming about his knee. The prevalence of anterior cruciate ligament, or ACL, injuries and the attention they get are remarkable – in seeing this scene, most people’s thoughts immediately go the ACL. Rarely do people see a knee injury occur in a movie or a game and think, “I bet that was their LCL”. Frankly, LCL injuries are relatively uncommon as compared to the ACL, but in any case – the ACL always seems to have this aura about it as the big one.

The ligament is important, certainly. There does appear to be some correlation between tearing the ACL and having a slightly higher likelihood of developing knee osteoarthritis down the road. The ACL does provide a lot of stability at the knee. While most people think of these injuries occurring with blunt-force trauma, a high percentage of these actually occur without any direct contact or trauma at all. For traumatic injuries, there is commonly a hyperextending force and/or a blow that forces the knee medially (inward); the ACL especially provides stability against these medial and posterior forces, so in the right positioning and with the right amount of force/rate of force, the ACL can be subject to tearing. This, however, does not mean that an ACL tear has definitely happened. But how would you know that the ACL tore?

One of the hallmark signs of an ACL tear is significant and near-immediate swelling. There is an intimate blood supply within the knee along the ligament; it appears that this close proximity may be the reason why ACL tears usually yield significant swelling. Again, this in of itself is not diagnostic; however, it appears that things like meniscal tears and other injuries tend to generate less relative swelling and generally have a slight delay to the onset of their swelling.

There are some clinical tests that can be performed as well, but these should be left to a clinical professional. An MRI is often done to confirm the suspicion of an ACL tear. More importantly, once an ACL tear is diagnosed, where do we go from here?

The most common pathway of management in the US is surgery. There is actually quite a bit of data to support that many people can rehab and recover without needing surgery (often referred to in the medical literature as “copers”). The goals for activity return appear to be a big factor – for example, if trying to get back to linear running or swimming, many people appear to be able to successfully rehab this without surgery, but it's worth noting that even sports requiring hard stops and direction change have had athletes get back at a high level without having surgery. Regardless, the surgery to reconstruct an ACL is very common and often very successful. There are several things that need to be kept in mind, though, with this pathway.

The physiology is crazy-impressive but takes time

The surgery is called a reconstruction as there is more involved than just sewing the two ends together. Sometimes the ligament may tear away (avulse) from the bone, and that requires addressing. Sometimes multiple structures may be involved (e.g., meniscal tear) which adds a layer of complexity in terms of getting back on your feet. In virtually all cases, some other tissue will be used as something of a bridge to reattach the torn parts. This “bridge” is often either cadaver tissue (an allograft) or a shaved piece of muscle/tendon from the patient’s own body (an autograft). The body has an incredible ability to identify this tissue and to undergo a remodeling process to have it function like a “normal” ligament. This process, though, takes time. As the body remodels, the strength of the repair actually diminishes for a short period, with the 6-week mark representing roughly the weakest point in time and with gradual increases in stability/strength of the ligament over time.

Disuse is rough on the body and on your recovery.

The typical patient with an ACL tear appears to be quite active. Depending on what all is involved surgically, you may even have delayed weightbearing (most common if there is a concurrent meniscus tear, although even this trend appears to be changing in some areas in recent years). There almost certainly will be no running in the near future after this reconstruction. Even with resistance training, some caution is warranted as to not stress the ligament excessively early on. There’s a reason that professional athletes don’t typically bounce right back from these – a year out of competition is pretty common, although some professional athletes may push this. It’s also worth considering that this level of athlete is typically living and breathing rehab in order to get back on the field or court. This period of being out of activity and facing limitations to activity may lead to muscles getting weak, your aerobic capacity reducing, and your capacity to perform your normal sports movements/tasks being less automatic.

Weigh the risk for return. Don’t rush it.

The research pretty strongly supports that the relative risk of re-injury or facing another significant knee injury is less when waiting upward of two years to return to sport (cue gasp). Rarely do athletes and competitors want to wait two weeks, let alone two years. It’s not all bad news, however. Even waiting until the one-year mark for competitive sports performance appears to be associated with a lower risk of injury or re-injury – we just have to weigh relative risk. However, rushing back to competitive sports (e.g., the 6-12-month window) does appear to be associated with a higher risk of sustaining a re-injury of the knee or a serious injury to the other knee.

What do I need?

Regardless of surgery or not, it is in your best interests to seek out a healthcare team that can effectively communicate (e.g., how you’re progressing compared to what is expected, when it’s safe to increase activity or to resume certain sports activities, etc.), a team that will push you just enough without risking safety (for optimal recovery and efficiency), and a team with the knowledge base to provide adequate testing to make sure that you are ready to get back out there with as little risk as possible. Our team has helped countless people get back to competing and performing ­– reach out to see how we can help you get back better than ever.

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