Happy Supposed-To-Be Opening Day everyone. Since the baseball season is (unfortunately) on hold due to the coronavirus pandemic, about the only recent baseball-related news to report has been that both Chris Sale and Noah Syndergaard (in addition to Luis Severino earlier this spring) are in need of Tommy John surgery. I covered some information about Sale’s injury and some discussion regarding techniques used in UCL reconstruction in previous blog posts. In the comment section of the latter post, TD user wabene asked an astute question about Rich Hill’s surgery and how it is similar or different from typical UCL reconstruction. Hill’s surgery is indeed different from a typical Tommy John surgery, and I thought a post about it might be interesting to some readers.
As usual, my disclaimer: I am not an MLB team physician. I have not seen or examined Hill or reviewed his imaging studies. I am not speaking on behalf of the Twins or MLB. I am only planning to cover general information about this type of surgery and my take on what it might mean.
Twins Daily contributor Lucas Seehafer posted an excellent article about Hill’s surgery back in January that was a good look into the surgery basics and some background about UCL primary repair. There was some additional discussion in the comments as well. Since Lucas did such a nice job covering the surgery, I won’t go into excessive detail in this post, but I’ll give my version of the basics, and then cover how Hill’s surgery is similar and different.
Basics of UCL Primary Repair
As covered in my post about Sale, the UCL is a strong ligament at the inside of the elbow that resists the stretching forces that occur when trying to throw a baseball. Obviously, hurling a baseball 90+ mph can take a toll on this ligament and it can, in some cases, result in a tear. These tears can occur at the top (humeral) end, bottom (ulnar) end or in the middle (called midsubstance).
The figure above is from a study we did when I was in fellowship indicating the location of the ligament injury in 302 patients who had undergone surgery with Dr. Andrews. The most common areas of injury are at either end of the ligament, with the humeral end being slightly more common (at least in this series) than the ulnar end. These patients all underwent UCL reconstruction, which is the standard operation to treat these injuries when non-surgery treatments have failed to result in adequate improvement.
More recently (I would say within the past 5-7 years), there has been emerging interest in performing a different operation for a subset of these patients called UCL Primary Repair. This operation differs from UCL Reconstruction in that when the repair is chosen, the injured ligament is reattached back to the bone at the site of the injury using special anchors. There is typically also a strong stitch called an ‘internal brace’ that is passed across the joint along the path of the repaired UCL as well. I often refer to this internal brace as a ‘seat belt’ stitch. The idea behind the internal brace is that early in the healing process, before it has re-developed strong attachments to the bone, the ligament is susceptible to reinjury which could cause failure to heal (or compromised strength of healing). The internal brace (theoretically) helps protect the healing ligament and allows for development of a stronger attachment back to the bone. Once healing has occurred, the internal brace is thought to act like ‘rebar’, adding some strength to the ligament (though the exact magnitude of this contribution is unclear).
This figure illustrates the repair technique with the blue ‘internal brace’ also in place.
This is different from UCL reconstruction, where tissue from elsewhere in the body (typically either a forearm tendon called palmaris or a hamstring tendon called gracilis) is passed through bone tunnels and used to create a ‘new’ ligament.
One of the reasons for the interest in primary repair of the UCL has to do with the length of time needed for recovery from UCL reconstruction. As many of us know from having watched numerous pitchers undergo (and subsequently return from) Tommy John surgery, there is usually around 12-18 months needed for full return to pitching at the major league level. There are a number of reasons for this long time frame, but a major contributor is that this is the amount of time needed for the graft to fully heal. Recall, we are taking a tendon (which normally attaches muscle to bone) and putting it in the place of a ligament (which normally attaches one bone to another bone). Though tendons and ligaments are similar, there are differences in their microscopic structure. Over time, as the graft starts to heal and have new stresses placed on it (namely throwing), it begins to change its microscopic structure and actually becomes a ligament. In fact, there have been animal studies done that have shown that a biopsy of a sheep ACL graft (which was originally a tendon) over time evolves into what is nearly indistinguishable from a ligament. We call this process ‘ligamentization’, and it is probably the most important part of what allows the new ligament to withstand the stresses of throwing.
This process, however, takes time. And because of this, the recovery from UCL reconstruction is lengthy. With primary repair of the UCL, this process of conversion of the tendon to ligament is not necessary since we are repairing the patient’s own ligament back to its normal position. Some healing is still required; namely the healing of the detached ligament back to the bone where it tore away. But this process does not typically require the same amount of time as the ligamentization process.
So why, then, wouldn’t everyone who needed surgery for this injury just have a primary repair? In practice, there are a few issues that require consideration when choosing what surgery is most suitable for a particular athlete. The first brings us back to the first graph from this post regarding location of injury to the UCL. It turns out that asking an injured ligament to heal back to bone is a much different thing than asking a torn ligament to heal back to itself. Specifically, trying to heal a tear in the midsubstance of the UCL (which requires the two torn edges of the ligament to heal back together) results in a much less strong situation than a ligament healing to bone. That makes those injuries that involve the midsubstance of the UCL (about 12% in our study) not suitable for primary repair. It can only be realistically considered in those athletes who have an injury at one end of the ligament or the other.
In addition, there is significant consideration given to the overall condition of the ligament. One can imagine that repairing a nearly pristine ligament that has a single area of injury (one end pulled away from the bone) is a different situation than trying to successfully repair a ligament that has a poorer overall condition. Imagine looking at a piece of rope that is suspending a swing from a tree branch- if the rope is basically brand new, but for some reason breaks at its attachment to the swing, it seems logical that reattaching the rope to the swing securely is likely to result in a well-functioning swing with less cause for concern about repeat failure. Conversely, if you examine the rope in the same situation and notice that it is thin and frayed in a number of places, but just happened to fail at its attachment to the swing, you would be much less likely to try and repair the existing rope. More likely, you would go to the store and buy a new rope to reattach the swing (analogous to reconstruction). Similarly, when we are considering surgical options, we examine the overall health of the ligament on the MRI scan, and also during the surgery to determine whether repair is suitable or whether a reconstruction is needed. If there is a significant amount of damage to the UCL on MRI, primary repair may not be presented to the athlete as an option.
Also, consideration is given to the particulars of an athlete’s situation. For example, let’s say I see a high school junior pitcher who has injured his elbow during the spring season. Let’s also say that he wants to return to pitching for his senior year but has no interest in playing baseball competitively beyond high school. In this case, the athlete is trying to return relatively quickly (the next spring) and is not planning to place long term throwing stress on the UCL beyond the next season. If this athlete fails to improve without surgery (such that all agree a surgery is needed), and his MRI is favorable- he is a good candidate for UCL primary repair. This would hopefully allow him to return in a shorter time frame (6-9 months) for his senior season, which would not be possible if a reconstruction was performed. Indeed, this is the exact type of patient that first underwent this type of surgery by Dr. Jeff Dugas at American Sports Medicine Institute in Birmingham, AL. Dr. Dugas is a protégé of Dr. James Andrews and has been instrumental in pioneering the research behind UCL primary repair.
As you can probably imagine, the longer players (and pitchers in particular) play baseball, the more likely it is that there is an accumulation of damage to the UCL over time. This is the factor that most commonly eliminates the option of primary repair of the UCL in many of these players.
So how does any of this relate to Twins pitcher Rich Hill? Let’s discuss.
Hill underwent UCL reconstruction of his left elbow in 2011. He was able to successfully return from his surgery but has certainly faced his share of injury concerns since then (as described nicely in Lucas Seehafer’s article). This past season he began to have elbow pain once again and was placed on the 60-day IL as a result. He then underwent surgery on the elbow in October 2019 by Dr. Dugas (noted above). The procedure performed was a repair procedure, but in this case instead of repairing Hill’s own UCL, the repair was performed to reattach the previously placed UCL graft. I don’t have any first-hand knowledge of Hill’s surgery, but my best guess is that the technique was very similar to what was described above for a typical primary repair with internal brace. To my knowledge, this has not been attempted before in a major league pitcher.
There is data showing a relatively good return to play rate with primary repair that is very similar to UCL reconstruction. However, most UCL repair patients are much younger than Hill and the vast majority that have been studied to this point are not major league pitchers. There are a couple of ways you can interpret this data when it comes to Hill. One perspective is that he had a repair of a ‘ligament’ (his UCL graft) that was only 8 years old (since his TJ was done in 2011), and as such it likely doesn’t have as much cumulative damage as his UCL might otherwise have if he had not had any prior surgery. An opposing perspective would be that this is his second UCL operation, and even though his most recent surgery was not a reconstruction, the data that would be most applicable to him would be data regarding athletes who have undergone revision UCL reconstruction (meaning they have had a repeat TJ procedure after the UCL failed a second time). This data is less optimistic. Most studies would put the rate of return to play after normal UCL reconstruction around 85% (depending on exactly how you define successful return to play). In most studies, the rate of return to play after revision UCL reconstruction is much lower, around 60-70%. There are two MLB pitchers that I am aware of that have undergone primary repair of the UCL (Seth Maness and Jesse Hahn). Maness has yet to return to MLB and Hahn didn’t fare very well in 6 appearances in 2019.
Finally, my last input on this topic as it pertains to Hill is to imagine the specific position he is/was in. He is likely nearing the end of his career (he turned 40 in March 2020). He had a significant elbow injury that was not getting better without surgery. Presumably his choices were four:
1) Continue trying to rehab without surgery and see how it goes, understanding that the possibility exists that rehab may not be successful. (Perhaps a PRP injection could be tried)
3) Undergo revision UCL reconstruction with its associated 12-18 month recovery timeline, likely putting him out for all of 2020 with a possible return in 2021 at age 41.
4) Undergo this relatively new primary repair procedure with the possibility of allowing him to return to play for part of the 2020 season, but with a much less known track record. In fact, a basically completely unknown track record for his specific situation.
If that doesn’t seem like a list filled with great options, it’s because it isn’t. If I’m being honest, I think Hill probably made the best choice (presuming that he still has a desire to play), even with the unknowns regarding his recovery. He obviously couldn’t have seen this virus pandemic coming, but that would seem to make the choice even better since he is not missing any games (because none are being played).
For Hill’s and the Twins sake, I hope his recovery goes smoothly and he is able to return and pitch at the high level he is used to. He sure seems like a warrior and is certainly the kind of person that is easy to root for. But based on what we know about his situation, there is an element of uncertainty. If I were Hill’s surgeon, I likely would have told him that he had around a 50-60% chance to return and pitch meaningful innings after this type of surgery. Let’s hope the coin falls his way, and also that we can figure out how to best handle this virus and get everyone back to their normal way of life as soon and safely as possible.
Thanks for reading. Be safe everyone. Feel free to leave any questions in the comment section.