Over the past day or two I have aggregated research on the bi-patellar tendon injury that afflicts 4th-round draft pick Greg Childs. What we can learn from the research is below. Before that, a couple of things.

I am not a doctor. I have no medical training, and a high school understanding of biology.

I have not consulted a doctor for this story. I have not asked a doctor for his or her opinion, nor any other medical professional.



I have no medical training. I repeated that, because it bears repeating.

As it is, I've got a pretty good level of reading comprehension (so I like to think) and an excellent ability to do research. That does not mean I have the background knowledge to be completely consulted or quoted as fact in this instance.

I imagine there are medical professionals out there who can be easily contacted, and this is merely knowledge gleaned from the internet. If I'm wrong about any of this, please correct me.

Let's talk shop.

There's a lot to discuss when it comes to Childs' injury. Most people seem to be asking if his injuries are related (and therefore predictable), if the injuries are recoverable and what the nature of the injury is. I've taken the liberty of gathering links from several sources as well as accumulated the bulk of the specific reporting on Childs' injury. The most natural thing to start with, however, is what the injury is. That will be below the jump

A patellar tendon is also referred to as a patellar ligament, and the reason that there are two names is that the patellar tendon performs the function of a ligament (connecting bones to bones), but has the tissue of a tendon (traditionally connecting muscles to bones) There's a bunch of science words that explain the difference, but the point is that it should surgically be treated as a tendon, which means that a more complete healing process can begin with mild activity within a week.





Here's a picture of a patellar tendon:





Courtesy of Wikimedia. It's the tendon labeled "Ligamentum Patelle"

Don't be confused by the two different spellings of the tendon; it seems as if both "patellar" and "patella" are commonly used names for the tendon.





The patella is your kneecap. The tendon pulls your kneecap away from the quadricep so that it slides smoothly in place. It allows you to bend your knee straight—without it, your kneecap slides up (towards your hip) as your quadricep contracts. That is, your kneecap will literally be sitting atop your femur. If you attempt to stand with a torn patellar tendon, your knee will buckle and give way (and you'll fall).





There are two types of tears for this tendon: partial and complete. Partial tears are usually the result of weaker tendons, and there are several causes for weak tendons. The two most obvious (and least likely) explanations for weakness in Greg Childs' tendons are chronic disease (usually associated with diabetes or chronic renal failure) or steroid usage, particularly steroids injected near the knee. Neither of these explanations is likely, largely because athletes do not tend to inject steroids in their knees (and doctors tend to avoid medical steroids in the knee for this reason) and many would have noticed a chronic disease by now.





The last explanation is the most logical reason that Greg Childs may have weak tendons, and that's Patellar Tendonitis—a specific type of inflammation that causes microtears and swelling throughout ones life. This type of tendonitis can be induced by athletic activity (and is common for basketball and volleyball players) or by a systemic illness.





Much of the athletic activity that leads to this sort of tendonitis can possibly be traced to low ankle flexion , and an ankle injury—like the one Childs suffered in a game against Ole Miss—increases the likelihood of Patellar Tendonitis.





Had Childs suffered from this condition as a result of a systemic illness, other side effects would have presented themselves, as most patients are 10-16 years old when the first signs aggressively assert themselves. There are several grades of induces tendonitis, and most athletes do not go beyond the first level of this condition, which is knee pain after activity. Risk factors (like playing on a hurt ankle) will move the athlete up these grades. Incidentally, this theory of tendonitis formation is called the Davidson Theory.





Induced tendonitis causes tears much like traumatic injury, and should be treated the same way. This cause for tendonitis is not chronic, and therefore not associated with future injury. Commonly, Stages 1-3 are healed with normal methods for treating pain or inflammation in joints, namely rest and ice





There is some likelihood that when Childs returned to play for Arkansas his senior year that he rushed his return from the tear, which would be a contributing factor in further tendonitis. As the inflammation dies down after 6 months and full extension is returned by then, it is a possibility, but once again unlikely, that poor rehabilitation caused a recurrence.





Childs' Pro Day improvement over his Combine performance is surprisingly a good exterior sign that he had healed, tendonitis and all.





Still, it seems more likely that poor rehabilitation (potentially aided by the use of corticosteroids) caused a repeat injury than an underlying condition.





Surgeons should be able to tell if the tear was induced by athletic activity (gradual or sudden) by the placement of the tear . If it occurred near the kneecap, it is the result of a sudden trauma or athletically induced tendonitis. If it occurred in the middle of the tendon, it was caused by weakening of the tendon as a result of a medical condition or steroids (regardless of whether or not the steroids were used to treat the tendon).





Here, I'll speculate a bit more than I have already, and argue that because such medical information was freely available to me, it was readily available to the medical consultants that advise the Vikings in the scouting process. There is a high likelihood, in my opinion, that these consultants (who may be medical proxies or the Vikings training staff) knew about the location of the tear and advised appropriately.





A torn patellar tendon is generally not completely recoverable , but athletes can often return to 90% of their previous strength. Most patients will require 12 months to reach all of their physical goals, although it will likely take substantially longer for two torn tendons, because using the uninjured leg while strengthening the ability to bear weight is a critical part of the process.





Patellar tendon tears in both knees is referred to as a " bilateral patellar tendon rupture ." There have only been two recorded instances of a bilateral tear occurring in two separate spots on the tendons, so it is extremely likely that both tendons tore near the patella—which is better than the alternative, chronic tendonitis that would not just doom Greg Childs' career, but sentence him to a life of pain.





of those 50 cases. Nevertheless, the Childs case is relatively unique in medical literature. A 2009 review found only 50 cases of bilateral tears in English and German medical literature, and rupture in the absence of a systemic disease or corticosteroid use only occurred in a small percentage of the time









One of the closest examples comes from a 1994 paper , where a 26 year old former collegiate athlete with no history of related medical conditions came down from a jump, and tore both patellar tendons. As this paper is behind a paywall, I cannot give you the full result, but the abstract implies that they are a model for return from bilateral simultaneous patellar tendon tears, which further implies success.





Another, more striking, case occurred in 2004 when a 47-year-old athlete who had previously torn his right patellar tendon tore both of those tendons at once. While these tears were 15 years apart and not two, the principles should largely be the same. While I can't get access to the conclusion of the paper—it's behind another paywall—the abstract indicates some degree of success.





The cases of bilateral patellar tendon ruptures are few and far between, so it is difficult to come to a conclusion about recovery times and effectiveness. None focused on high level athletes in their prime, and only a few focused on athletes at all. Most of the cases not dealing with degenerative tissue damage in the tendon indicate that there is usually a recovery that allows walking, running and jumping, but not full leg strength—that is rare. Because athletic margins in the NFL are razor thin, it is easier to be pessimistic than optimistic, although I am willing to revise the completely cynical outlook I took on this issue before.





If "extensor lag" and "swing speed" (the amount of time that it takes a leg to go from one step to another in a full run) are the same thing, then we might have a reason to be even more optimistic, as many of the patients returned to "no extensor lag."





Most of the papers on this issue do not deal with acute tears, which require twice as much recovery time—those four months may look more like eight, and full athletic recovery could take longer than a year (although this is admittedly a little extreme).





Full recovery (to game speed) seems unlikely, but not nearly as unlikely as I had initially thought. Further, much of these cases do not involve the type of access that an athlete is typically afforded. Childs was able to get into surgery as soon as possible, which is recommended because the tendon could start to shrink, rendering it largely inoperable or useless. The longer the athlete is out of surgery after the tear, the less likely they are to recover. It is in fact the biggest factor in predicting recovery success.





There are a few protocols that Childs may have gone through, but almost all of them are variations of suturing the tendons. There is the possibility that there has been an allograft from a cadaver (taking tendon tissue from a body), but that's unlikely in the case of immediate surgery. More likely, Childs received sutures that were wound through holes drilled in the kneecaps. These sutures may be wire, cable, or strong thread.





In some cases, there's a suture anchor drilled into the kneecap, where the thread goes around the anchor (which often looks like a bolt) instead of through the kneecap. It seems likely that the suture method used on Childs before will be used again.





The most popular suture method is the Krackow method, which has a unique stitching pattern that avoids the problem of "bone staples" (now considered obsolete) and one that allows the center of the tendon to attach to the bone while using the outside of the ligament to create the holding spots for the sutures. Here it is below:





Courtesy of a website that is now dead

This is all information that Eric Sugarman has and will apply as he moves forward with the rehab schedule. There's still innovation to be done in this field, and we can be confident that Sugarman and his staff will do their best to find the most effective ways to return Childs from injury. While there's no reason to expect success, there is certainly a lot of room for optimism.

Again, we wish Childs the best, and a speedy recovery if at all possible.