Science of Baseball: The Brian Roberts Hamstring Injury

As Birdland digests the news that the MRI results on second baseman Brian Roberts' leg after last night's hamstring injury revealed a tendon rupture - suffered while sliding headfirst into second base - they do so with a collective and concomitant groan and sigh. A groan of displeasure upon hearing Roberts befallen with yet another injury, and a sigh, accentuating the feelings of helplessness and bad luck for Roberts, with this latest setback occurring so early into the 2013 season, after a promising spring training that saw Roberts free of the lingering effects of the concussion, sports hernia, and hip labrum tear that has hampered his on-field efforts over the last two years.

Roberts is no stranger to the hamstring injury, as his Steadman's Medical Dictionary-like Baseball Prospectus player card injury history can attest; Roberts started the 2011 campaign day-to-day with some hamstring soreness. However, with his description of hearing a 'pop' behind his knee while taking the last couple of steps before starting into his slide, and the aftermath culminating in his being helped off of the field, unable to put weight on the leg, one got the feeling that this latest affliction will be more than a day to day endeavor to overcome. With the MRI providing us the final diagnosis, let's learn a little more about the anatomy of the hamstrings and what types of injury are associated with them.

Anatomically, the hamstrings are a collection of three muscles – the semitendinosus, the semimembranosus, and the biceps femoris – that run down the back of the leg, starting at the hip and extending down past the back of the knee. At the knee, these semitendinosus and semimembranosus tendons attach close to one another on the medial surface of the tibia, with the long and short head portions of the biceps femoris muscle coming together and forming a common tendon that attaches on the lateral head of the fibula.

Illustration from American Academy of Orthopaedic Surgeons (aaos.org)

 

Functionally, the hamstring muscles perform a number of duties and are a crucial muscle group in athletics activities, due to their input while walking, running, and jumping. Their multiple functions arise from the muscles crossing and acting upon two joints – the hip and the knee. Collectively, these muscles allow you to extend your leg behind you and also flex your knee; inward and outward rotation of your lower leg while your knee is bent is also possible due to the hamstrings.

There are different types of hamstring injury – there are strains, along with partial and complete tears, and are graded by severity. Grade 1 muscle strains are the less severe injury, and are easily treated with RICE (rest, ice, compression, and elevation), immobilization, and occasionally physical therapy, which is used to help in restoring muscle strength and flexibility. Grade 2 strains bring with them more pronounced tearing of the muscles compared to a Grade 1 strain, and affect the gait of the athlete along with the associated swelling and pain. Grade 3 strains are complete muscle tears and produce immediate excruciating pain, as well as the inability to bear weight on the affected leg. More severe than the Grade 3 muscle strains is an avulsion injury, where the tendon is torn off of its bony attachment, occasionally pulling away bony element with it. Surgery is most frequently used in avulsion injuries, but can also be performed on more severe muscle tears. In terms of frequencies, the biceps femoris muscle is most injured muscle of the hamstrings; tendon avulsions are more common seen in the pelvis than the knee.

So what does this all mean for Roberts?

For the Orioles infielder, he had the unfortunate luck of sustaining the less common tendon rupture – one that arises from the knee. His previous history of hamstring injury not only put him at an increased risk for suffering not only another injury, but one of increased severity. That being said, the news of surgical options not being explored right away is encouraging, and that the RICE, immobilization, and physical therapy approaches previously described will suffice for a complete recovery from the rupture for Roberts.

Any injury is bad news; for Roberts, given his history, and his production from both a defensive and offensive perspective being predicated upon strong legs, it's a little more devastating. While his injury looks to keep him away from going under the knife for the time being, with his position not only as an oft-injured member of the Orioles, but also an elder statesman of the team, one cannot learn of this this latest setback without a sense of foreboding. For now, Orioles fans can only hope for the best, and hope that more time away – from the field and the operating room - will heal this wound.