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Knee Ligament Discovery Could Bring New Twist To ACL Treatment

posted 5 Jan 2014, 13:49 by Mpelembe   [ updated 5 Jan 2014, 13:50 ]

Two Belgian surgeons have described a previously unidentified ligament inside the human knee, which they say appears to play a role in the recovery of patients with anterior cruciate ligament (ACL) tears, an injury common among athletes. The doctors say their discovery could revolutionise ACL treatment, and produce better outcomes for patients.

LEUVEN, BELGIUM (REUTERS) -  Publishing their research in the Journal of Anatomy, knee specialists Steven Claes and Johan Bellemans of the University of Leuven have closely mapped the fibrous band which links the outer side of the upper bone (femur) with the lower bone (tibia), and named it the anterolateral ligament (ALL).

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They suggest the finding could be key to treating one of the most common injuries in sports, tears of the anterior cruciate ligament (ACL), which are oarticularly prevalent among soccer players.

The ACL is the most significant of the four major ligaments which surround the knee joint. It is located directly in the centre of the knee, criss-crossing between the upper and lower leg bones to provide stability.

An injury to the ACL can occur when someone changes direction or stops abruptly. Whether mild or severe a tear or rupture can cause knee instability and further injuries to other ligaments.

Professor Bellemans, who has supervised Dr. Claes in his research, says they wanted to understand why some patients continue to suffer, after recovery, from frequent 'pivot shifts' where the knee gives way during exercise.

"When somebody tears his ACL and he undergoes surgery we know that there are 10 percent to 20 percent of patients who continue to have some form of instability. That is unlogical because we fixed what was broken, therefore we were convinced there had to be another structure which was damaged also but which remained unrepaired so far," said Bellemans.

Claes says that after investigating 41 cadaveric knees over four years the doctors found that, in most cases, people who had torn their ACL would have had their other ligament disrupted as well.

"The human ACL is located deep in the centre of the knee but the ligament that we have described is running at the lateral side of the knee, somewhere over here and while the ACL is controlling AP instability meaning from front to back, this ligament is controlling rotation of the knee, this movement. What we noticed is that in many ACL injured subjects, that both ligaments seemed to be disrupted. So you can expect that if you only treat one of this injuries that some laxity and some instability, especially this rotational laxity will persist after an operation for instance," said Dr. Claes.

He added that despite advanced surgical techniques, up to half of athletes are not able to perform at the same level as before the rupture.

"In all (medical) papers you could see a relatively high number of people who are not able to return to their pre-injury level of sports. Some papers state 75 percent, 80 percent of people who are able to return for instance to soccer, but if you look into detail almost 50 percent of the cases, sometimes 40 percent of the cases at the level they used to play, especially the high level, they need to drop down a league or they are not just as good enough, they feel a little bit uncomfortable or unstable," said Claes.

The surgeons believe the anterolateral ligament could play an important protective role in restraining excessive rotation of the knee as athletes pivot.

Across the world, the study has sparked markedly different reactions from other knee surgeons, ranging from excitement to heated criticism.

FIFA-accredited surgeon Marc Martens, who has operated on many top soccer players with ACL injuries, is sceptical of the findings. Martens says they were not a major breakthrough in sports medicine, since an ACL tear affects far more structures than just the small band.

"It's more than just this ALL, it's more than just this little fibre band. We should realise that it's more. All these structures on the lateral side, including the ALL are damaged and stretched and that's why you have to make sure if you reconstruct that once you do something that we have done in the past, take something strong and make sure that you have good fixation on both sides and put it on the right place," said Martens.

Nevertheless, he gives credit to Dr. Claes for bringing to attention a significant structure and technique that he says has been forgotten by many surgeons.

"It is important because we have today still a too high percentage of failures after ACL reconstruction and one of the factors to be considered to understand the failures of all ACL reconstruction is certainly related to the fact that one forgot to stabilise for pivoting," said Martens. The surgeon added that he has been practising a similar technique for decades, using an extra fixation on the anterolateral knee area to prevent re-tearing of the damaged ligament.

Drawing on the works of French surgeon Paul Segond in 1879 and American Dr. Jack Hughston who identified similar structures, Dr. Claes noted this is the first time a detailed description of the ALL has been clearly established.

Other surgeons suspect that the recently found band could be a possible hypertrophy (increased volume) of the anterolateral part of the knee capsule, insisting that further studies were necessary to prove it was a true ligament from a macroscopic anatomical perspective.

The Belgian surgeons have already started to offer repairs of the newly described ligament.