I published a data-based evaluation of Blake Corum a few weeks ago, much of it centered around the dynamics of his pre- and post-injury efficiency and through-contact success. In its final paragraph, I wrote that your opinion of Michigan’s all-time rushing touchdowns leader probably “comes down to your level of confidence in his ability to return to pre-injury form”, and I maintain that position today. However, due to some combination of personal oversight and the tendency of reports to describe Corum’s injury, surgery, and recovery in rather general terms – often referring simply to his “knee” – I somewhere along the way came under the misapprehension that we were talking about an ACL tear.

As has perhaps been obvious to some of my readership, Corum did not tear his ACL but rather his meniscus, as well as suffering an MCL sprain and a bone bruise in the same (left) knee. In the original article, I shared a link to a study by Matthew Betz (a physical therapist who writes injury analysis for the Fantasy Footballers) that showed the second year after returning from ACL reconstruction to be the big statistical bounce-back season for running backs who’d suffered the injury. I’m inclined to believe that those findings still hold in a broader sense for knee injuries in general, but I wanted to research the implications of the injuries that Corum actually sustained to check my optimism about his long-term recovery and, by extension, his potential to contribute well to NFL and dynasty fantasy football teams. This article will outline what I learned – including standard return-to-play timetables, differing implications of the various kinds of relevant surgical procedures, re-injury rates, dynamics between pre- and post-injury performance, details of Corum’s own recovery process, notable recent examples of other running backs returning from similar injuries, and more – through that research.

Let’s start with the details of Corum’s injury. While his final appearance in his great 2022 season came against Ohio State on November 26th, it was late in the second quarter of the previous week’s game against Illinois that he was actually hurt. With 1:45 left in the half, Corum bounced outside on a power run, took what appeared to be an indirect and innocuous hit to the lower body near the sideline, and went down in pain:

Corum described an immediate and “unreal” burning sensation that lasted for about 10 seconds after the hit. When it subsided, he felt like he might be able to go back in the game, speculating that he might have suffered “a little hyperextension”, and after some halftime X-rays and ligament observation that all came back clean, he took a pain pill and headed out for the second half. “Something didn’t feel right” on his first carry of the third quarter, however, and he ended up sitting out the rest of the game and taking things easy over the next week.

During that time, Corum was diagnosed with a torn meniscus, a grade II MCL sprain, and a “deep” bone bruise, but also told that these issues weren’t going to worsen if he played on them. Being the gamer that he is, Corum suited up against the Buckeyes, but “felt his leg give out” on both of the two early carries he had in the game. That marked the end of his junior season.

The bone bruise seems not to have been particularly consequential in the calculus of Corum’s treatment, nor the MCL sprain: grade III sprains involve full ruptures of the ligament, are severely painful and “grossly” unstable, and are often accompanied by ACL tears, but a grade II is typically treatable with physical therapy and generally comes with a return-to-play timeline of a few weeks. The meniscus was the big issue in this case.

Tears of the meniscus – which is “a piece of cartilage that acts like a shock absorber between [the] femur and tibia” – can apparently vary widely in severity, which largely dictates treatment options. Minor tears result in discomfort and swelling but can sometimes be played on (as Corum attempted to do), while major tears can result in the locking of the joint and other mechanical issues in the functioning of the knee. There seem to be two main types of surgery for repairing meniscal tears: meniscectomy “to remove the offending piece” in the case of smaller tears, and a full, suture repair in the case of larger tears. I have not found reports of Corum suffering from the sort of locking issues that sometimes accompany a more severe tear, but he ended up undergoing a complete meniscus repair operation in the days following the Ohio State game.

That appears to be a good thing, at least compared to the meniscectomy alternative. In this article about Kelvin Benjamin’s torn meniscus from back in 2017, Dr. Clifford Rios points out that the risk of “another injury causing a larger tear” is problematic with such a procedure, and goes so far as to say that (at least for NFL linemen) the surgery “is more detrimental to knee function and career length than an ACL injury.” The advantage of meniscectomy seems to be that it comes with a significantly shorter return-to-play timeline than full repair (on a time-scale of weeks versus months), but this 2023 study concluded that “meniscal repair is a more biologically preserving procedure of the knee joint and should be performed preferentially over meniscectomy in isolated meniscal tears when feasible.”

Setting aside the differences between individual types of treatment, let’s take a look at the performance-related implications of meniscus injuries in general, for which this 2022 study on recovery by soccer players in top-level European leagues is especially illuminating. I’d recommend the whole study to anyone who is interested, but – based on research covering 250 players from the English Premier League, Bundesliga, La Liga, Ligue 1, and Serie A who suffered meniscus tears between 2006 and 2016 – here are the broad strokes:

As Corum is not a player in an elite European soccer league, we obviously can’t assume these findings will completely and directly apply to his situation, but it strikes me as encouraging that the circumstances surrounding his meniscus tear and recovery jive with the kinds of things you’d like to see from a Premier League player who incurred the same injury: he’s well under 30 years old, he did the running back equivalent of scoring a lot of goals prior to having been hurt (in other words: he was a notably productive player pre-injury), he underwent full surgical repair, and he returned in year one to the same level of competition he’d played at prior to injury. Check, check, check, check. Perhaps with more direct relevance, this 2018 study on professional athletes (primarily in football, soccer, and basketball) recovering from either meniscus repair or meniscectomy procedures displays findings that are similarly positive: “of athletes undergoing meniscal repair, 86.5% RTP at their pre-operative level.” This statistic is contrasted with those undergoing meniscectomy, who RTP at an 80.4% rate.

I want to finish this article by surveying the post-injury performance and recovery timelines for some recent running backs who also suffered meniscus tears. Detailed information about the severity of injury and surgical method involved in these cases is not easy to find, so one-to-one parallels between these and Corum’s situation can’t be fully assumed, but I think this anecdotal information is helpful as a supplement to the scientific studies outlined above.

Let’s start with Mark Ingram, who “underwent arthroscopic knee surgery” for a torn meniscus as a 21-year old in late August of 2010. At the time, he was coming off a sophomore season in which he gained nearly 2000 yards from scrimmage, scored 20 touchdowns, helped lead Alabama to a National Championship, and won a Heisman Trophy. In his first post-injury season (with his debut coming fewer than three weeks after his surgery, so I’m assuming he had a meniscectomy), he handled 5.3 fewer touches per game and averaged 0.58 fewer yards per carry than he had the previous year.

The 5.54 yards that Ingram produced on a per-rush basis as a junior was still a respectable mark among SEC backs (it represented greater efficiency than future NFL-ers Vick Ballard, Marcus Lattimore, and Stevan Ridley posted that year), but the injury and subsequent dip in performance from the heights of his stellar 2009 campaign scared off some pro executives. This Evan Silva article from the spring of 2011 tells of “rumors that the long-term stability of Ingram’s knee is tenuous”, with Mike Lombardi speculating about “degenerative arthritis” and reporting two unnamed “teams that need running backs” who told him Ingram wouldn’t be on their draft boards due to his “very bad” knee. Nonetheless, Ingram was taken in the first round and – after two seasons of producing less than four yards per carry to start his career – ended up as a multi-time Pro Bowler with impressive longevity.

Our next example comes courtesy of Chris Johnson, who played nearly the entire 2013 season – when he was 28 years old – with a torn meniscus. Perhaps unsurprisingly, he posted a then-career-low mark of 3.86 yards per carry that season, though it’s also worth pointing out that his Success Rate that year was the highest it had ever been (assisted no doubt by an offensive line that Pro Football Focus rated as the league’s eighth-best run-blocking unit).

Johnson ended up undergoing meniscal repair surgery (like Corum) in the following offseason. As a member of split backfields with the New York Jets and then the Arizona Cardinals over the next two years, he bounced back to average 4.26 and 4.15 yards per carry, respectively. He was never CJ2K again, but at 29 and 30 years old – even if he had never torn the meniscus – should we really have expected him to be?

Next is Adrian Peterson, who tore the meniscus in his right knee back in September of 2016. He was 31 and had a pretty extensive injury history at the time (even going back to college), though his reputation as a superhuman healer had also been well established by that point. He underwent a full meniscal repair in the following days, reportedly spent $10,000 per week on rehab and recovery to get back before the end of the season, did return for a week 15 matchup with the Colts (in which he went 6-for-22 on the ground), but was deactivated the rest of the way (though – while I’m not positive – this seems to have been as much due to the Vikings receiving their seventh loss and falling out of playoff contention that week as it was due to any additional complication from Peterson’s injury).

That marked Peterson’s last game with the Vikings. He averaged just 3.39 yards per carry with the Saints and Cardinals the following year, but he did return to post one final 1000-yard season with Washington at the start of a two-year stint that saw him average 4.20 yards on nearly 500 carries (the ninth-highest total for any player in the league during that span). After that, he played another two seasons before calling it quits at age 36.

Derrius Guice, who was a teammate of Peterson’s in both of AD’s seasons in Washington, tore a meniscus of his own in week one of 2019 (after having torn his ACL in the other knee a year prior). The then-22-year old underwent surgery and was back by week eleven (so he probably had a meniscectomy; head coach Jay Gruden called it a “minor procedure”), after which he averaged over seven yards per carry over the next four games. In that fourth contest, though, he suffered yet another knee injury, this time an MCL sprain in the same knee in which he’d torn his ACL. Guice’s absence from the league in the years since can be partially attributed both to these health issues and to a litany of legal troubles and off-field character concerns.

Our final example is Jeff Wilson Jr., who suffered a “substantial meniscus tear” while simply standing up in the 49ers’ locker room deep in the 2021 offseason. He underwent surgery the next day and was given an RTP timeline of 4-6 months (indicating the procedure was a full repair rather than a meniscectomy). The 26-year old returned to the lineup by week ten but averaged just 3.72 yards per carry in his nine games of action that year (down from his previous career average of 4.43), though he has been remarkably effective in the two seasons since: he averaged over five yards per carry with San Francisco in the opening half of the 2022 campaign before producing 4.64 yards per attempt across 18 games with the Dolphins over the last year and a half.

(I should quickly mention Kendre Miller, who suffered a knee injury – variously reported as an MCL sprain and/or a meniscus tear – as a 20-year old with the TCU Horned Frogs on New Year’s Eve back in 2022. He underwent surgery to repair his MCL and ended up sitting out the athletic testing components of his pre-draft process as a result, though it’s unclear if his meniscus was also worked on. It was reported on August 14th of 2023 that he suffered a “knee sprain” in a preseason game, though also that the injury wouldn’t require surgery. Just a few weeks later it was reported that he “was dealing with a new hamstring injury”. The fantasy PTs were just as confused throughout that ordeal as you likely are reading this paragraph, which is why I’ve opted to banish this anecdote to the confines of a parenthetical. For whatever it’s worth, Miller averaged 2.96 yards per carry between weeks three and nine in 2023, though he went 13-for-73 on the ground in the season finale after missing most of the second half of the year with an ankle injury.)

So what does this all mean for Corum? I want to make clear that I am a lay person with no medical expertise and no first-hand knowledge of the injury and recovery processes of any of the players mentioned in this article, but I do think the research I’ve compiled here should be encouraging for those considering Corum in rookie drafts this spring. He satisfied many of the pre-injury conditions that positive recovery is often dependent on in elite athletes with meniscal tears (most notably, he was both young and good at his sport), and his post-injury process has apparently gone rather smoothly as well. The simple fact that he underwent a full meniscal repair rather than a meniscectomy seems to portend good things for his longevity (along with the scientific studies shared above, the anecdotal evidence from our small sample of NFL runners indicates that full repair is preferable to meniscectomy as well), and he already returned to his previous level of competition and – while his efficiency took a dip from where it had been in the previous two years – was clearly still an effective player overall. If the precedent set by Ingram, Peterson, Johnson, and Wilson is anything to go by, then 2023 probably showed us the least explosive version of Corum that we can expect to encounter in the next few years. If that’s the case, then he’s very much in play as the potential RB1 in this year’s draft class and as a guy who we shouldn’t expect to experience physical deterioration any more quickly than we would for a back who hadn’t torn a meniscus. As long as pre-draft medicals come back clean, I’m not concerned with his short- or long-term outlook.