Allen Craig and his Knee: A Primer

Greg and I put in a lot of work to kind of force it to bend through the pain.

Allen Craig, c. June 13, 2011

As a Physical Therapist, this quote from Allen Craig continues to make me physically wretch. Words like "force it" and "through the pain" are typically very frowned upon during the rehabilitation process. The only times that this type of action is OK during treatment is when contracture of a joint is present (i.e capsular adhesions, scar tissue buildup in chronic cases). To force a joint to bend "through the pain" during the acute phase (Craig injured his knee on June 7, 2011) is never OK.

After the jump, a timeline...

So, a timeline:

June 7- Craig runs into fence at Minute Maid Park

Sometime between June 7 and June 13- "Greg and I put a lot of work to kind of force it to bend through the pain."

June 13- Craig hits the DL

June 14- X-ray reveals small fracture in patella (knee cap)

August 10- Craig activated from DL


Sometime around November 17- Craig undergoes surgery

(VolsnCards steps on soapbox). Now, I want everyone to take a close look at the above timeline. Notice how the x-ray shows a fracture after Craig and the Cardinals rehab team "forced" his knee to bend? I'm not saying that sickening experience caused the fracture, but I will say that it certainly could worsen a pre-existing issue (chipped bone, small fracture, etc). I know there is a lot of pressure from both player and organization to get injured player back on the field ASAP, but that should never cause the medical staff to force a joint through pain (especially in the acute phase). I can't shake the feeling that if Craig had just been given a couple weeks to heal without overly-aggressive stretching, he might not have needed surgery. (steps of soapbox)


Now that I have that off my chest, let's talk about the patella. The patella is the largest sesamoid bone (bone embedded in a tendon) in the body. As you can see from the diagram linked here*, the patella is "held" in place by the quad and patellar tendon(s), which are the connective tissue that connects the muscle to bone. Just as the tendons "help" the patella by keeping it from floating into space, the patella "helps" the quad muscle and tendons by providing a mechanical advantage for the extension moment. Basically, the patella increases the angle of pull that the extensor mechanism can manage, effectively increasing leverage. Basically, without your patella, extension of your knee would be less efficient and much less forceful. As knee extension is a component of pretty much every lower extremity action you make during a day, this would be a major problem. You can see why a fracture in the patella is not an optimal situation; the bone is literally being stressed at all times.


All the reports I have seen regarding Craig's surgery indicate that two screws were placed through his kneecap to stabilize the bone. My guess is x-rays taken before surgery showed that the bone was not healing (whether it be a complete non-union or some other factor) quickly enough for Craig and the Cardinals. This, mixed with the pain/discomfort he was still experiencing, led to the decision to go ahead with surgery. Patellar fracture is actually a fairly common injury. Often, surgery is not necessary, as the bone will heal with conservative treatment (bracing and strengthening as able). Unfortunately, surgery is sometimes necessary, especially if you are attempting to return to high level athletics in a timely fashion. There are two main ways to surgically stabilize the bone: tension band wiring or screw fixation. It would seem that the screw fixation method was chosen for Craig. During my research for this post, I found an article from SBN sister site Roto Hardball that serves as a nice primer on the Allen Craig injury. It also contains a picture of the initial injury and an x-ray showing patellar fixation with two screws (note: not Allen Craig's knee). The screw method is probably the most "stable" but also takes the longest to rehab. I am sure they chose to insert screws due to the high demands Craig will put on his patella as a high level athlete.


Physical Therapists often follow specific protocols after major reparative surgeries, usually due to restrictions placed on the patient by their surgeon. This is especially true after rotator cuff, labral, and ACL repairs. Having said that, patellar fixation surgery isn't something one sees every day. A cursory search of the internet and the American Physical Therapy Association research website turned up no rehabilitation protocols specific to this type of surgery. However, I have little doubt that the PT will be following similar guidelines to the protocol linked here. This is a fairly typical ACL reconstruction (patellar tendon graft) protocol, and since many similar concerns exist with Craig's rehab, this is probably the type of plan being followed. I would like to point out that most ACL protocols prohibit open kinetic chain (OKC) knee extension exercises (knee extension without foot planted on ground and with weight put at ankle) due to the shear forces this puts on the ACL graft. This won't be as big a no-no for Craig, though it is still a slight concern due to the relationship between over-exercising in the OKC and patellar tendinitis (I'll get to that later).


A 4-6 months recovery time is what we are hearing, and I would concur with this prognosis. Most major knee surgeries (and make no mistake, having two screws put into your fractured kneecap is a major surgery) take 3-6 months to rehab due to a number of factors. I like to tell my patient's that quad muscles (specifically the VMO) go to sleep quickly and are hard to awake. If the patient lacks normal quad control, which is common after knee surgery, functional tasks such as sit to stand transfers, squatting, and ambulating can be very difficult. This is compounded when the patella or surrounding tendons are affected by the surgery (common with ACL surgery as many orthopedic surgeons use a piece of the patellar tendon as the graft for reconstruction).

To combat this, many post-surgical rehabilitation protocols call for the patient to wear a brace locked in full extension for several weeks post-op, which decreases the stress on quad muscle and para-patellar tendons. Some protocols even call for decreased weightbearing on the affected leg (I haven't seen anything regarding Craig's weightbearing status). What we have seen is that Craig expects to be out of his brace by the second week in January. My guess is that Craig was locked in full extension for several weeks, but has recently been allowed to unlock the brace with walking. He is avoiding steps currently, which is likely due to decreased quad, specifically eccentric, control (eccentric control is what allows a person to step down without collapsing). Poor quad control is present for several reasons. First, the muscle size and strength has decreased due to disuse atrophy. Second, the neural connections have, for lack of a better word, disappeared. Recent research has shown that the first 6 weeks of rehab after surgery is more about re-establishing neural connections from brain to muscle and less about actually increasing muscle size, quantity, and overall strength. Basically, this means that currently, Craig is not strengthening the quad musculature. After about 6 weeks, which would be around Dec. 22nd, Craig's efforts to strengthen and increase size of muscle will start bearing fruit. Remember though, he's had 6 weeks+ of muscle atrophy, and it takes a months after neural re-connection to return quad to pre-injury strength, not to mention surrounding musculature.

All of this talk of muscle will lead some people to forget about the bone. This would be a mistake. The patella is a bone and acts like a bone. Once a bone is fractured, it begins going through an intense healing process that can take a year or more to complete (depending on a number of factors, including age, health, and genetics). In Allen Craig's case, the fracture was small (how small is a matter of discussion), but even a small fracture can be troublesome when located on the patella due to its importance (see above). Time is needed to allow proper healing, even with the added stability provided by the screw fixation.

Allen Craig does have some things going for him. He's young, he was stronger than your average patient going into surgery, and he has a really good reason to do whatever he can to return to his sport at a high level (read: he wants his monies). Due to these factors, and barring complication (see below), I could easily see Craig ready for a return to sport at 5 months, which would be mid-April. If everything goes perfectly, He might even be able to start participating in baseball related tasks by the end of spring training.


There are two potential complications that could arise during Craig's rehab and post-surgical athletic life. Medical studies are notorious for SSS, but we can usually glean some information from them regardless. A recent study showed that 1 in 3 patients who undergo fixation of the patella need a second surgery some months later (11 on average) to remove the implants in knee due to pain, infection, or general irritation. Obviously, this is a concern for Craig. The good news is that this study showed that none of the patients who had screw implants needed revision or removal (once again, this is all very SSS, but it's the best we have).

The second potential complication is the bane of sports/orthopedic PTs everywhere: Patellar Tendinitis. I won't bore you with all the details, so if you want to investigate this further, the Wikipedia post on patellar tendinitis is surprisingly well done (some nice diagrams as well). Basically, patellar tendinitis is an overuse injury that often occurs in athletes and post-surgical patients. Allen Craig is both of these and is at real risk of developing this condition. It often occurs when too much stress is placed on the patellar tendon due to quad weakness; basically, the patient does too much too fast and the quad can't keep up, leaving the patellar tendon out to dry. Once this condition develops, it can be tricky and tedious to keep at bay, so avoiding it all together in the first place will be at the top of Craig's rehab team to do list.


Allen Craig, due to his age and pre-surgical fitness levels, should have a fairly normal rehab. Assuming nosetbacks or complications, I see no reason why he won't return to the Cardinals by mid to late April (5 months). He may even be able to return to baseball activities by the end of spring training. The rehab team must do a good job of monitoring his progression so he does not end up with patellar tendinitis.

*the copyright laws re: images found on the internet confuse me; hopefully i'm not breaking any laws by linking to these pics

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