Orthopedic community debates structure, function of anterolateral knee ligament
Results from this debate, new findings may alter the way ACL-deficient knees are treated.
For several decades, the anterolateral ligament of the knee has been scrutinized by orthopedic surgeons and researchers, leading to a wide-scale debate on the existence of the ligament, its function and best treatment methods.
“One of the biggest issues with the [anterolateral ligament] ALL is that the name anterolateral ligament has been used for a number of different structures over the years, so the nomenclature is not as concise or as consistent to the literature as one would want,” Alan Getgood, MPhil, MD, FRCS (Tr&Orth), complex knee surgeon at Fowler Kennedy Sports Medicine Clinic, University of Western Ontario, in London, Ontario, Canada, told Orthopedics Today. “Therefore, that often leads to some discussions to whether this truly is a structure or not. I think with the number of studies that have come through now, it is shown that there is a structure there.”
The believers define the ALL as a structure that may tear in conjunction with ACL tears, especially when the knee is subjected to extreme internal rotation that may occur in high-level athletes who ski or play soccer, for instance. Proponents of the ALL also say it possibly plays a role in Segond fractures, a small tibial plateau bone chip identified in the late 1800s by French surgeon Paul Ferdinand Segond, that may occur in high-energy rotatory knee injuries.
Non-believers in the ALL contend it is most likely the iliotibial (IT) band, or a deep layer of the IT band, that is affected in these situations, along with other structures in what they call the anterolateral complex. Opponents to the ALL concept say those are the areas that must be addressed in conjunction with these knee injuries, especially when the ACL is torn.
“I think [the debate] is because there are different ways of looking at [the ALL],” Robert F. LaPrade, MD, PhD, complex knee surgeon at the Steadman Clinic, in Vail, Colo., said. “If you look at some of our European colleagues, they have looked at cadaver specimens that are preserved in formalin, the old-fashioned way, and when you look at it that way it obliterates the tissue planes. It is a little bit harder to see exactly what happens when you flex and extend the knee, so it can look a little bit thicker probably than what we see with fresh cadavers.”
The existence debate
Recently, the existence of the ALL was debated at the European Society of Sports Traumatology, Knee Surgery and Arthroscopy Congress by Steven Claes, MD, PhD, of Belgium, and Freddie H. Fu, MD, DSc(Hon), DPs(Hon), of Pittsburgh.
Claes, who contends the ALL exists and whose anatomical research with colleagues on embalmed cadavers in support of that claim was published in the Journal of Anatomy, said during the debate, “I think it is better to join forces in this field for the best of our patients.”
Based on his dissections, imaging and biomechanical studies, clinical experience and review of the literature, Fu noted the anterolateral complex — which is formed by the IT band and connects to the femur as described by Kaplan — the deep capsule-osseous layer, as well as the anterolateral capsule, synergistically limit knee internal rotation. Of all these structures, the IT band plays the most important role.
“The key is to do an accurate layer-by-layer dissection,” Fu, who is chairman of the Department of Orthopedic Surgery at the University of Pittsburgh Medical Center and is an Orthopedics Today Editorial Board member, said. “Anatomy is persistent, whereas dissection is variable as represented by the conflicting anatomical descriptions of the ALL. As the late anatomist Pau Golanó, MD, often said, we should look at nature, but not create nature.”
Getgood said orthopedists should “move on from the debate” about whether the ALL exists, and focus more on “how best to control rotatory laxity in an ACL-deficient knee.”
According to LaPrade, it is rare for the ALL to be injured in isolation, with injury to the ALL usually associated with an ACL injury or injury to other lateral ligamentous structures.
“I have never, in all of my years of practice, [seen] an isolated anterolateral ligament injury,” Thomas L. Wickiewicz, MD, attending surgeon at Hospital for Special Surgery and professor of orthopedics at Weill Cornell Medical College, said. “You cannot rotate the knee far enough with an intact ACL to damage that tissue.”
Claes told Orthopedics Today he started studying the ALL when his patients who underwent perfectly executed, anatomical ACL reconstructions had a substantial pivot shift (PS) — excessive anterior translation and internal rotatory instability — that persisted.
“Simplified, one could say the ACL attests for this excessive anterior translation while the ALL deficiency then leads to this internal rotatory instability with both phenomenon present in the positive PS test,” he said.
“The ALL story can explain a few of these cases,” Claes said, noting the orthopedic community must look beyond the ACL when treating ACL-injured patients and athletes who pivot from their knees using extreme amounts of energy and require a perfectly stable knee.
Fu, who has studied knee ligaments and extra-articular knee structures for about 40 years, told Orthopedics Today that sometimes during ACL surgery other extra-articular work is indicated.
The ACL, PCL, medial collateral ligament and lateral collateral ligament are well-defined, he noted.
“We cannot imagine a ligament that we are not sure is there. It is not reasonable even to imagine something that is so important, people do not even agree that it is there,” Fu said.
He said the Kaplan fibers, capsulo-osseous layer and the strong superficial IT band form the anterolateral knee complex which forms a protective wall around the knee. When the complex is intact, the rest of the knee structures are adequately supported. Procedures, such as extra-articular tenodesis, that reinforce that complex may help to support a well-executed ACL reconstruction, yet these may potentially over-constrain the knee, according to Fu.
To highlight the different structures on the lateral side of the knee, Fu said during the debate, “I would propose we call this whole structure the anterolateral complex. I think we can talk and then we can improve the whole knowledge and move forward.”
“There have been a number of studies now that are starting to convince us that the anterolateral complex is analogous to the posterolateral corner of the knee,” Getgood said. “We have an anterolateral corner and this complex or group of structures all work in combination through the flexion-extension arc to control anterolateral rotary laxity.”
Getgood noted several publications have suggested the ALL, as well as the deep layer of the IT band, are responsible for the Segond fracture.
“[The ALL] acts as a rotatory restraint and thus affects the PS. It explains the Segond fracture, which has been proven, as well, and a combined ACL plus ALL reconstruction indeed does work. I must admit, though, there is still plenty of work to be done,” Claes said.
Repairing the ALL
When it comes to repairing the ALL, LaPrade noted treatment will depend on the type of injury associated with the ALL injury.
“If there is a Segond fracture and you see [the patient] acutely within the first couple of weeks and they have a big PS, it is probably reasonable to do a primary repair,” LaPrade said.
However, he only recommends performing an acute primary repair if there is a significant increase in the patient’s PS.
“Unless there is a huge PS, I would not advocate trying to fix it acutely unless [the surgeon] definitely saw something like an avulsion fracture there, like a Segond fracture,” LaPrade said.
According to James R. Andrews, MD, medical director and founder of the Andrews Institute in Gulf Breeze, Fla., “Anterolateral reconstruction with a hamstring graft to help modify and stabilize” the ACL has gained popularity.
“We are not doing [ALL] reconstruction in all cases of ACLs because a lot of [patients] do not have that type of increased rotary instability and do not need anything done over there,” Andrews said.
He added, “A lot of doctors are pushing to use that on all ACL reconstructions, and we have not found that to be necessary at all. It is just the more complicated cases [in which] we use it.”
Getgood noted a lateral extra-articular tenodesis may be a better treatment method than an ALL reconstruction.
“Although [ALL reconstruction] has been developed and publicized, it has not been fully validated biomechanically or clinically. More studies that are being performed now looking at the biomechanics of ALL reconstruction show that it may not be as useful as we think,” Getgood said.
According to Getgood, although lateral extra-articular tenodesis has been around for years, the use of the technique in the United States has declined due to several studies that showed a lack of efficacy and some degree of over constraint in the knee. However, he noted previous studies used old-fashioned techniques that are no longer in use and were underpowered. A recently published study by Getgood and colleagues showed “tenodesis had a greater effect in controlling anterior translation and internal rotation than an ALL reconstruction,” Getgood said.
According to Wickiewicz, there may be no reason to repair the ALL after injury.
“You cannot put a stout ligament off the center of rotation close to the joint without greatly affecting the normal motion of that joint,” Wickiewicz said. “So, the ALL tissue is like a bungee cord on purpose. It allows the rotations to take place. You put different tissue there and constrain it, that does not make sense to me.”
Similar to the debate as to whether the ALL exists, Getgood noted surgeons should use whichever surgical technique provides the best control of rotatory laxity.
“We just need to work out what is the most efficacious way of actually controlling that rotation,” he said. “We are doing some biomechanical studies now looking at the difference between ALL reconstruction and lateral tenodesis to see if we can try and improve our current surgical techniques, but we are a little way off yet. We are also nearing completion of recruitment in a 600-patient multicenter randomized clinical trial [Stability Study], investigating the use of lateral extra-articular tenodesis in young patients at high risk of re-injury following ACL reconstruction.”
Getgood noted future research should provide a “consistent nomenclature for the anterolateral capsule and the structures in the anterolateral aspect of the knee,” as well as a further understanding of the differences between ALL reconstruction and the lateral extra-articular tenodesis.
“We should be trying to work out which patients would benefit from an anterolateral reconstruction, as not everybody who has an ACL injury needs to have an extra procedure performed, so we need to more clearly define the indications,” Getgood said. “Then, once we know what type of reconstruction works best and we understand the indications, we need to know if it makes a difference clinically. Hopefully, the results of the Stability Study will shed some light on these questions.”
Andrews noted further research is needed on placement of the ALL during reconstruction on both the femur and the tibia, as well as where the ALL is tightened and by how much.
“You can over constrain the knee on that side of the joint if you put [the ALL] in with too much flexion and tighten it up too much,” Andrews said. “Then [the patient] will develop [loss] of full extension and an external rotation contracture, which is not good for the knee. It is critical to make sure that you regain isometric motion to full extension with no loss of normal internal rotation of the knee joint.”
Fu supports good quality, scientific research that is reproducible to independently validate the studies by Claes and others about the ALL. This should be done before proceeding with clinical trials to prevent any potential harm to patients, he said.
However, Wickiewicz noted that with previously published research showing no additional stability or function from the ALL in the case of a stable ACL, there is little need for further research on the topic.
“[The ALL] does not engage until the joint is displaced, so I do not see any need for further research on the ALL,” Wickiewicz said. “I am not a believer in the reconstruction of that ligament because the tissue parameters are so different you are just going to grossly over constrain the joint. So, I think it is a done issue, personally.” – by Susan M. Rapp and Casey Tingle
- Claes S, et al. J Anat. 2013;doi:10.1111/joa.12087.
- Fu F, Claes S. Debate: Does anterolateral ligament exist? Fact or fiction. Presented at: European Society of Sports Traumatology, Knee Surgery & Arthroscopy Congress; May 4-7, 2016; Barcelona.
- For more information:
- James R. Andrews, MD, can be reached at 1040 Gulf Breeze Pkwy., Suite 203, Gulf Breeze, FL 32561; email: firstname.lastname@example.org.
- Steven Claes, MD, PhD, can be reached at AZ Herentals, Nederrij 133, 2200, Herentals, Belgium; email: email@example.com.
- Freddie H. Fu, MD, DSc(Hon), DPs(Hon), can be reached at 3471 Fifth Ave., Suite 1011, Pittsburgh, PA 15213; email: firstname.lastname@example.org.
- Alan Getgood, MPhil, MD, FRCS(Tr&Orth), can be reached at 3M Centre, University of Western Ontario, 1151 Richmond St., London, ON N6A 3K7, Canada; email: email@example.com.
- Robert F. LaPrade, MD, PhD, can be reached at 181 West Meadow Dr., Suite 400, Vail, CO 81657; email: firstname.lastname@example.org.
- Thomas L. Wickiewicz, MD, can be reached at E. 70th St., New York, NY 10021; email: email@example.com.
Disclosures: Claes reports he is a paid consultant for Arthrex. Getgood reports he received research support from Arthrex and a research grant from the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine and Orthopaedic Research and Education Foundation (Stability Study). LaPrade reports he is a consultant for and receives royalties from Arthrex, Ossur and Smith & Nephew. Andrews, Fu and Wickiewicz report no relevant financial disclosures.
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