Many athletes involved in running sports (e.g., rugby, soccer, football, basketball) with fast starts and sudden stops injure their hamstring muscle. Of course, the first thing they want to know is how long will it take to recover and get back in the game? The answer is not always so easy to provide. It seems recovery time varies significantly from player to play. Not only that, but second injuries to the same muscle can occur, especially if the player goes back to the game too soon.
In this study, researchers from Australia evaluate the use of MRIs to predict recovery time from hamstring injuries. They particularly focus on hamstring injuries that involve disruption of the central tendon.
The hamstring muscle is the large muscle along the back of the thigh. It is made up of three muscles and their tendons: the biceps femoris, semimembranosus, and semitendinosus. The central tendon runs down the center of the muscle for the full length of the hamstrings.
The reason this tendinous portion of the muscle is important is because injury to this area often means a longer, slower recovery. Using MRIs to assess hamstring muscle injury might aid the surgeon in making predictions about expected length of time for recovery. Returning to sports activities too soon is linked with an increased risk of reinjury. Avoiding recurrent damage to the hamstring muscle is an important goal.
To find out if MRIs can be used in this way, the records of 62 elite athletes with hamstring injuries were reviewed. Each one had MRIs taken. The investigators could compare the results and the recovery time for hamstring injuries in players with central tendon disruption against players with hamstring muscle injuries.
MRIs showed that central tendon disruption only occurred in injuries involving the biceps femoris. Almost half (45 per cent) of the hamstring muscle injuries of the biceps femoris included central tendon disruption. Comparing recovery times, it was clear that recovery took much longer for injuries involving the central tendon.
In general for all the players combined, recovery time varied from as short as two weeks up to six weeks. Comparing injuries to the three hamstring muscles (semimembranosus, semitendinosus, and biceps femoris), the recovery time was the same. In other words, there was no significant difference in recovery time for the three hamstring muscles.
Recovery time for central tendon injuries of the biceps femoris was much longer (72 to 91 days). Tendons have less blood supply than muscle fibers so this delay in recovery when the central tendon is injured makes sense. The shorter time (72 days) was for players with this type of injury who were treated conservatively (without surgery). The longer recovery time (91 days) was associated with players who had surgery to repair the damage.
The authors conclude that hamstring injuries involving the central tendon do take much longer to heal. And MRIs do have prognostic value. They can help identify this type of injury early, which can help surgeons and players plan treatment and return-to-sports accordingly. Central tendon disruption can be seen on MRIs and is considered a new prognostic sign. This is the first study to report on the value of MRIs in finding central tendon disruption.
The next step in research is to examine whether different treatment (surgery versus conservative care) and different rehab programs yield better results for these two distinct injuries (muscle versus tendon). Risk of recurrence and recurrence rates should also be studied for hamstring muscle versus hamstring (central) tendon. Some studies have already been done looking at the severity of hamstring injury and time to recovery. The authors of this study point out the need to also compare severity of muscle versus tendon on recovery rates.