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What Trainers Need to Know about LARS Reconstruction for ACL Ruptures


Anterior Cruciate Ligament (ACL) injury is a frequent client problem encountered by personal trainers, and fitness professionals must understand this injury and its treatment options as they are often asked for information on surgical procedures by their clients as well as having a role in the later stage post operative rehabilitation process.

It is also vital than fitness leaders are kept informed of any new developments in the treatment and repair of common injuries. This article will focus on one of these new developments—the Ligament Augmentation and Reconstruction System (LARS)—and its use in the repair of a ruptured ACL.

Review of ACL Anatomy and Injuries

Injury to the ACL can occur in any physical activity that requires twisting, changes of direction or jumping—all activities commonly associated with group exercise classes and personal training sessions. The high profile of ACL injury due to its occurrence in elite athletes make this injury a subject of much interest.

To review our anatomy: the ACL runs up (superiorly) and back (posteriorly) from its attachment on the front of the tibial plateau to its femoral attachment at the back of the intercondylar notch of the femur. This important ligament prevents forward movement of the tibia in relation to the femur, assists the control of the knee, and delivers proprioceptive information to the brain that informs us of internal knee stresses and body position. The name "cruciate" refers to the cross, or crucifix, the ACL makes with the Posterior Cruciate Ligament (PCL) inside the knee. These ligaments—the ACL and PCL—have also been referred to as the “crucial” ligaments in recognition of their importance in sporting knee performance.

A Magnetic Resonance Image (MRI) is the investigation of choice for a definitive diagnosis of an ACL rupture and will usually be arranged by the treating specialist. Once the diagnosis of ACL rupture is made, the patient must decide between a non-surgical and a surgical treatment approach. Some factors involved in this decision include the person’s age, degree of instability, exercise and sports demands, occupation, cost, and the person’s conviction to follow the time-consuming postoperative  rehabilitation protocol. It's worthwhile to note that the use of the new LARS system may remove some of  the postoperative issues that make the more traditional surgical repair a somewhat long and arduous process.

What is the LARS System?

The Ligament Augmentation and Reconstruction System (LARS) has been in the research and development stage since the mid 1980s and has been used in some European countries since the early 1990s, but is only just beginning to be more commonly used by Australian surgeons. The LARS products were approved by Health Canada in September 1993, but the have not yet been approved by the Food and Drug Administration in the United States.

The LARS protocol involves the use of industrial strength polyester fibers (polyethylene terephthalate) attached to the bones to replace injured ligamentous structures like the ACL. It is believed that the polyester fibers and the arrangement of the actual knit pattern allow these artificial ligaments to bend and twist, but at the same time resist stretching that would make the new ligament ineffective in controlling joint stability.

The Lars Ligament The Lars Ligament

The LARS designers also believe that the structure of the artificial ligament allows for some tissue ingrowth where the ends of the injured ligament actually grow into the graft making it even stronger and more like the original ligament.

The LARS Surgical Procedure and the Ligament in Place The LARS Surgical Procedure and the Ligament in Place

What are the Advantages of a LARS Artificial Ligament to Repair an ACL?

While this system is still in its relatively early stages, there does appear to be some distinct advantages in using this method when compared to more conventional ACL reconstruction methods such as the more commonly used hamstring or patellar tendon graft—where part of the patient’s hamstrings or patellar tendon is removed and made into an artificial ACL.

Some of the advantages of the LARS system may include:

The Lars Ligament 18 Months Postoperatively The Lars Ligament 18 Months Postoperatively

Rehabilitation Essentials for Personal Trainers

Strength training is a vital component of the rehabilitation following ACL injury and surgery. The majority of strength exercises used in pre- and postoperative ACL protocols are classified as closed chain (i.e., an exercise done with the foot on a stable surface).

Examples of closed chain exercises that are useful in this protocol are leg presses, Swiss ball squats, lunges and step-ups, as well as more advanced balance activities such as one-leg medicine ball squats. These closed chain exercises allow the lower limb to be compressed, thus reducing shear forces across the knee, as well as allowing the quads and hamstrings to work together to stabilize the knee joint.

Open chain exercise such as leg extensions have little role to play in rehabilitation following ACL rupture and are usually contraindicated in the first six months following surgery due to excessive shear forces being placed in the new ACL graft. There is still debate among fitness professionals and medical experts as to the relative merits of the leg extension exercise in even the healthiest knees; I personally believe that unless you are a competitive bodybuilder, you have more effective and time-efficient exercises for quadriceps development than the leg extension.

Some suggestions for fitness professionals involved in post ACL surgery rehabilitation—regardless of the exact procedure performed include:

Implications for the Personal Trainer

It is vital that all fitness professionals have at least a basic understanding of some of the more common surgical procedures as it is often the case that many postoperative patients turn to fitness centers and personal trainers for advice on getting back into shape and increasing function after a significant injury—like an ACL rupture and subsequent reconstruction.

The early results seem to support the claim that the LARS system reduces postoperative immobilization, pain and swelling that is a common feature of the more traditional ACL repair protocols. The fact that the LARS ligament is strong and solid immediately may lead to more aggressive rehabilitation and more rapid return to sport.

However, as with all injury and rehabilitation issues make sure you work closely with the client's medical team – physical therapist and surgeon – to ensure that the correct exercises are done at the right stage and at the correct intensity. Don’t make the mistake of thinking that just because the ACL has been re-constructed using the LARS method that you can fast track the client back to full exercise. To do so would place you at risk of litigation and the client at risk of graft failure and another trip to the surgeon.

Conclusion

The LARS system looks to be a good alternative to the more conventional reconstruction procedures available to clients with an ACL injury. However, the procedure is still in its infancy in many countries and all patients need to do thorough research and speak to their surgeon before deciding on which reconstruction method to use and if the LARS system is an option for them.

References

  1. Brukner, P. and Kahn, K. ( 2002). Clinical Sports Medicine – Brukner and Khan, Revised Second Edition. McGraw-Hill Companies.
  2. Cerulli, G. et al. (2007). ACL reconstruction using artificial ligaments: Five years follow-up. S.I.O.T, 33 (3suppl. 1), pp. 8238-8242.
  3. Lavoie, P. et al. (2000). Patient satisfaction needs as related to knee stability and objective findings after ACL reconstruction using LARS artificial ligament. The Knee, 7, pp. 157-163.