Examining Glenn Dorsey's Biceps Tear as Injury-Plagued 49ers Preseason Continues

Dave Siebert, M.D.Featured ColumnistAugust 5, 2014

San Francisco 49ers' defensive end Glenn Dorsey celebrates a tackle during the first half of an NFL football game against the Seattle Seahawks, Sunday, Sept. 15, 2013, in Seattle. (AP Photo/John Froschauer)
John Froschauer/Associated Press

As if the San Francisco 49ers needed another serious injury, defensive tackle Glenn Dorsey suffered a torn biceps over the weekend, an injury that might end his 2014 season before it begins.

ESPN's Adam Schefter reported the news Saturday afternoon.

Schefter later followed up on the injury, adding that Dorsey needed surgery, one reportedly scheduled for Monday.

Despite the troublesome news, CSNBayArea.com's Matt Maiocco wrote Sunday that the 49ers "are holding out hope [...] Dorsey will be available to play late in the regular season." Nevertheless, a biceps tendon tear, which is similar to many major muscle tendon tears, will almost definitely cost Dorsey, at the very least, the vast majority of the regular season.


What (Probably) Happened?

Muscle tendon tears often occur when an outside force counteracts the muscle in question's primary action. For example, if an opponent forces a lineman back onto his heel while the lineman is contracting his calf—and therefore the Achilles—in an attempt to push forward off the ground, the Achilles can tear off the back of the heel.

Similarly, if a hit to the elbow causes a player's arm to suddenly straighten while the biceps is trying to bend it, a tear may result. Sudden jerks of a flexed arm forward—for example, something pulling the arm straight out while the athlete is trying to bend it—can also cause the injury.

The biceps consists of two muscle bodies, seen here in red and green. Together, they rotate the forearm outward and flex the elbow.
The biceps consists of two muscle bodies, seen here in red and green. Together, they rotate the forearm outward and flex the elbow.Wikimedia Commons.

The exact circumstances of Dorsey's tear are not entirely clear. That said, in a press conference video (via CSNBayArea's coverage of the injury included in Maiocco's article, 49ers defensive coordinator Vic Fangio said Dorsey was "playing a block" and "came off" at about the time the injury took place.

Presumably, something or someone caused his arm to suddenly and sharply straighten before the lineman was ready.


Could Dorsey Play with a Torn Biceps?

The biceps, which actually consists of two separate muscle bodies and three tendons, one at the elbow and two at the shoulder, is not the only muscle group responsible for bending the elbow. As such, a player might maintain full range of motion at the joint, as well as a reasonable amount of strength, following a tear.

Non-surgical rehab remains an option if an athlete can maintain enough strength to play at a high enough level despite the injury. A tear of one of tendons near the shoulder may lend itself to such an outcome, as other muscles, including the other biceps muscle body and tendon, can compensate.

Nevertheless, a rupture of the tendon at the elbow—the only connection point of the biceps muscle bodies to the forearm—may result in too much loss of function. After all, when it comes to playing on the defensive line in the NFL, any decrease in strength might prove too much to overcome.


What's Next?

Unfortunately, tendons often do not heal well on their own for several reasons.

For instance, a ruptured tendon might retract away from the point to which it previously attached to bone. Furthermore, a tendon's relatively low blood supply may not allow for strong healing. As a result, surgery often becomes necessary.

During the operation, a surgeon will reattach the ends of the biceps tendon or the tendon back to the bone from which it came. The rehab that follows consists of exercises that focus on gradually increasing the amount of stress the athlete places on the tendon as it heals together.

Owing to the relative slow healing of muscle tendons, in addition to the large amounts of stress they must absorb on a regular basis when healthy, complete ruptures usually requires months of rehab, not days or weeks. Placing too much demand on a tendon before it is ready can lead to reinjury.

Additionally, it should not come as a surprise if 49ers doctors decide to treat Dorsey with platelet-rich plasma (PRP) therapy. A relatively new, legal technique, PRP involves injecting an athlete's own platelets in and around an injury to assist the healing process.

PRP remains largely unproven and a subject of intense research. That said, it shows promise in select musculoskeletal conditions, and it probably carries minimal risk.


Bottom Line

As of Monday night (Aug. 4), a few question marks still lingered about Dorsey's precise prognosis.

While the phrase "season-ending" surfaced shortly after the injury, a source of Pro Football Talk's Mike Florio mentions the tackle could return late in the season following a projected four-month recovery. Such a scenario indeed remains a possibility if the operation and rehab go well.

The 49ers' willingness to use the "injured reserve with designation to return" tag may also come into play.

Despite this optimism, however, a biceps tendon tear represents a significant injury by any stretch of the imagination. For now, 49ers fans should be prepared to, at the very minimum, go the vast majority of the season without Dorsey.


Dr. Dave Siebert is a resident physician at the University of Washington who plans to pursue fellowship training in Primary Care (non-operative) Sports Medicine.