Two serious knee injuries for Liverpool. What are ACL injuries?

October 16, 2015

In the midst of all the excitement that comes with the arrival of a new Manager, it has been a disastrous week for Liverpool on the injury front. Two of its best young players, both of whom only arrived in the summer, sustained serious knee injuries They both tore their anterior cruciate ligament (ACL). Joe Gomez injured his knee while playing for the England U21 team against Kazakhstan on Tuesday night. And then at training on Wednesday striker Danny Ings tore his ACL.

ACL injuries, which are seen mainly in sports such as netball, basketball and skiing as well as the various football codes, are devastating for both player and club as they require a lengthy time off sport.

The knee relies on a number of ligaments for stability. Two of these ligaments are the cruciate (cross) ligaments, the anterior and posterior, named for the site of their attachment on the tibia (shin bone). See the figures below


Front view                                                                Back view


The ACL controls rotational movement of the knee and is most important in pivoting movements of the knee. It can be injured in three different ways – by direct contact (e.g. in a tackle), by landing from a jump with an outstretched knee, or by simply changing direction. The player will often hear a “pop” or feel like the knee has “popped out of place and back again”.

An ACL injury is typically very painful for the first few minutes and then the pain settles down, often leading to false optimism that the injury may not be so serious after all. Occasionally the player then goes back on the pitch only for the knee to collapse when they attempt a sudden change of direction.

The reason an ACL injury is such a serious one for a footballer is that because the ligament does not tear cleanly but is actually shredded, it cannot be directly repaired. Instead the ligament has to be reconstructed.

In an ACL reconstruction, the surgeon takes either a piece of the patellar tendon at the front of the knee or one of the hamstring tendons at the back of the knee, and creates a substitute ACL This involves drilling through the joint and inserting the new “ligament” attaching it with screws. The operation previously involved opening up the knee joint, but over the past two decades the reconstruction is performed through an arthroscope (telescope).

Following the surgery a lengthy rehabilitation program is required to return the knee to full function. The players work incredibly hard with the physiotherapy and fitness staff to restore the strength, balance and function of the knee. This process takes on average 8-9 months, so it is unlikely that we will see either of the Liverpool players again until next season. In most cases the player will make a full recovery and return to their previous level of play, although frequently it takes a season or two to achieve that.

Over the past couple of years, evidence had emerged that not all ACL tears require a reconstruction, and certainly many of these injuries in the non-elite sporting population can be managed with an intensive rehabilitation program alone. However at the moment, most high level athletes are treated with a surgical reconstruction of the ligament.

It has been a bad month for cruciate injuries in the Premier League. As well as the Liverpool pair, Bournemouth have had three players with ACL injuries – Tyrone Mings, Calllum Wilson and Max Gradel, while Newcastle goalie Tim Krul has also torn his ACL and will miss the rest of the 2015-16 season.

There is some evidence that preventive programs involving lots of balance work as well as education on jumping and landing techniques can reduce the risk of these injuries. Most clubs now incorporate these exercises into their training programs. However, as we have seen, they still occur, although for clubs such as Bournemouth and Liverpool to have more than one ACL injury in a season is very unusual.