On Rich Hill's Experimental Elbow Surgery and Previous Injury History

While the team may have struck out on acquiring their top-tier starting pitching targets — Zach Wheeler, in particular — the acquisition of slugging third baseman and former league MVP Josh Donaldson helped freshen the bad taste left in the mouth by the beginning stages of free agency.

However, one acquisition that has the potential to further cast the Twins’ offseason in a positive light is the signing of starting pitcher Rich Hill. Hill, a 15-year veteran who has split time between the bullpen and starting throughout his career, spent the previous three years and change with the Los Angeles Dodgers where he posted an ERA of 3.16 and struck out 427 batters in 361 1/3 innings.

Hill, who signed a one-year, $3 million contract laiden with performance incentives, largely resurrected his career during his stint with the Dodgers. Prior to joining L.A., Hill’s career was defined and marred by injuries and inconsistency. Other than four semi-successful seasons with the Chicago Cubs to begin his career — he posted a 4.37 ERA across 337 2/3 innings — Hill never threw more than 76 innings for any of the other six teams he made appearances for. and those productive 76 innings came while he was with the Oakland A’s in 2016, who went on to trade Hill to the Dodgers later in the season.

The majority of the injuries Hill has suffered during his career (see photo above) have occurred on the left side of his body, something that would be expected for a left-handed thrower; the throwing arm is subjected to an immense amount of force with each pitch and the muscle contractions within the push-off leg is the source of the power — itself a great amount of force — that serves as the foundation for every throw.

The two most significant of Hill’s injuries both involve his left elbow.

In 2011, Hill underwent Tommy John surgery to reconstruct the ulnar collateral ligament (UCL) in his left elbow. The UCL — along with the bony configuration of the elbow and the wrist flexor muscles — helps stabilize the elbow against valgus forces. A valgus force causes stress to the medial — or inner — elbow; if the soft tissue structures in the arm are unable to compensate for the vast amount of force placed through it while throwing a baseball, the UCL is usually one of the first structures to be injured. The UCL can be injured acutely - failure after one subjection to a high force — or chronically — a build up of “wear and tear” over the course of many throws.

Just like any other ligament in the body, the degree of injury of the UCL can vary. A grade 1 sprain of the ligament is analogous to a simple “over stretch”; these injuries aren’t usually severe and heal on their own over the course of a few weeks. The main treatment for grade 1 injuries is rest and ice.

Grade 2 and 3 sprains of the UCL involve tearing of the ligament, with grade 3 sprains being full ruptures. Grade 2 injuries may be able to heal on their own due to the UCL’s relatively good blood supply, so the first line of treatment usually involves targeted strengthening of the wrist flexors, a gradual return to throwing, and perhaps a platelet-rich plasma (PRP) injection or two. PRP injections involve removing some of the athlete’s blood, spinning the collected blood very rapidly to separate the red blood cells from the plasma, then injecting the plasma back into the elbow; the thought is that the plasma will boost the healing of the UCL, though the true efficacy of PRP injections is up for debate.

If conservative treatment for grade 2 and 3 tears fails, Tommy John surgery is ultimately required. Tommy John surgery — also known as ulnar collateral ligament reconstruction — involves creating a new UCL by grafting a piece of tendon - often from the hamstring or palmaris longus of the forearm - into the elbow. The physiological process of the body turning the tendon into a new ligament is, appropriately, known as ligamentization, and this combined with the amount of rehabilitation that is required for the athlete to return to game action can take some time. It isn’t uncommon for a major league pitcher to miss 9-18 months after undergoing Tommy John surgery.

However, this is where Hill’s latest injury needs to be discussed.

Hill underwent a largely experimental though highly encouraging procedure this past October to repair a partial tear of the UCL in his left elbow, known as a primary repair with internal bracing and was conducted by renowned orthopedic surgeon Dr. Jeffrey Dugas (Dr. Dugas studied under and now works with Dr. James Andrews in Alabama and, interestingly enough, is the Associate Medical Director for the WWE!). To my knowledge, pitchers Seth Maness and Jesse Hahn as well as outfielder Brandon Guyer are the only other professional baseball players to undergo this procedure as of this writing.

Not all UCL injuries are eligible to undergo Dr. Dugas’ procedure, however; the tear has to be relatively clean with defined edges. The biggest difference — besides the surgical differences outlined above — between traditional Tommy John surgery and the procedure Dr. Dugas performed on Hill is the typical recovery timeline. Athletes who undergo the primary repair with internal bracing procedure

When asked recently about his recovery timeline, Twins’ President of Baseball Operations Derek Falvey relayed that Hill will soon resume throwing. Said Falvey, “Rich will begin a throwing program or process here going into spring training ... Our hope is that he’s pitching in some rehabilitation games in June.” This would place Hill’s return to play at about 8-9 months, at least a full month, or likely much more, sooner than he would have had he undergone traditional Tommy John surgery.

However, as Falvey stated, Hill’s return and rehabilitation process isn’t set it stone. “[Hill’s return] is all going to be somewhat dependent on how he responds at each juncture. Could [his return-to-play timeline] speed up? Sure. Could it slow down a little bit? Absolutely it could. We just need to see how he is once he gets to a more aggressive part of his throwing program.”

That last clause is the most important aspect of Hill’s recovery; it would be wise for the Twins to bring Hill along slowly, making sure that his surgically repaired elbow responds positively (i.e. doesn’t hurt and is producing sufficient amounts of force) prior to progressing him in his throwing program; Hill’s starts in September, and hopefully beyond, are much more important to the Twins than his potential starts in June.

According to Baseball Savant, Hill has primarily utilized a two-pitch mix over the past four seasons; Hill’s four seam fastball and curveball usage percentage ranged between 44.9-55.4% and 36.0-49.2% respectively from 2016-2019. This is important as higher pitch velocities place greater amounts of stress on the inner elbow. It is important that Hill have adequately strong rotator cuff and wrist flexor muscle strength and endurance to help attenuate the forces placed on the inner elbow with repeated throws greater than 90 miles per hour.

If Hill is able to rehab without any hiccups it wouldn’t be out of the realm of possibility for him to return to his Los Angeles Dodger-levels. Perhaps the biggest obstacle to returning to prominence, however, would be Hill’s relatively advanced age — he’ll turn 40-years-old in March. All baseball players experience a decline in performance at some point and few have been able to carry high amounts of success into their 40s. However, with Hill’s contract being heavily performance-based, his signing was a low-risk, high-reward move for the Twins. If he returns healthy, Hill could be an extremely viable Game 3 starter behind Jose Berrios and Jake Odorizzi; if he doesn’t, the Twins still have Michael Pineda.

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