The LARS Procedure For Ruptured Anterior Cruciate Ligaments (ACL)

This was sourced from Sports Injury Doctor [sports-perform@nce.sports-performance.com]and Chris Mallac at http://rehabtrainer.com.au/

There is a new fad that has hit the orthopedic wards in Australia and it’s called the LARS procedure. Recently, some key and prominent professional Australian Rules Footballers (AFL) have successfully undergone LARS procedures for ruptured Anterior Cruciate Ligaments (ACL) and have returned to full competitive sport well within 4 months post operatively. Usually the best case scenario with the traditional ACL reconstruction, which uses a hamstring or patella tendon graft, is 6-7 months although most take more like 9 months. So what is all this fuss about?
 
The Anterior Cruciate Ligament

 
The Anterior Cruciate Ligament (ACL) is an internal knee ligament responsible primarily for stability of the knee, particularly in rotation. It also prevents the tibia (shin bone) from sliding forward in relation to the femur (thigh bone).

 
The ACL is common to rupture in sporting endeavours either by direct contact to the outside of the knee (e.g. being tackled awkwardly in Rugby) or more commonly from twisting it e.g. like a side step in field/court sports.

 
When ruptured they will not naturally heal and so require surgical reconstruction. Failure to do so will not only prevent the athlete from ever having a properly functioning knee again but will also likely result in the early onset of arthritis. Surgeons are divided on what they use to reconstruct the ACL but commonly hamstring or patella tendons are used.

"Because the surgeon does not need to use any of your own ligaments, he effectively avoids creating another injury – either to the hamstring or the patella tendon."

What is a LARS?

 
LARS stands for “Ligament Augmentation and Reconstruction System”. This is a synthetic ligament the surgeon can insert into the knee that directly mimics the normal anatomy of the ACL. The design of the LARS artificial ligament has an inner longitudinal core that allows fibres of the injured ACL to naturally grow along this internal synthetic scaffold of a ligament. The unfortunate patient who has just ruptured their ACL will need to have a remaining ‘stump’ of ligament left which can be attached to the bone. Preferably the stump is still attached to the femur.

What is the benefit?

 
Well here is the exciting thing. Because the surgeon does not need to use any of your own ligaments, he effectively avoids creating another injury – either to the hamstring or the patella tendon. The main benefits are that:
  • Athletes return to sport much quicker
  • No muscle wastage post-operatively
  • No lack in strength post operatively
  • Less pain and swelling post operatively
  • So what are the drawbacks?

Well the procedures are reasonably new in terms of being used on athletes so no one really knows. Researchers have not yet had a chance to fully assess long term complications with the LARS so questions such as “Do they breakdown after a period of time?” “And if so, how easy is it to redo a conventional reconstruction?” remain unanswered.
 
The biggest criticism that surgeons make is that the amount of bone that has to be drilled away to allow the LARS graft to be inserted is large. This will make any future surgery on that knee very difficult if they should unfortunately have a LARS which fails.
 
Furthermore, the ‘behaviour’ of the athlete post operatively may lead to early onset arthritis. If the athlete has a mindset that they can start running 6 weeks post operatively (as most of them can), then what damage are they doing to the other structures in the knee that were also damaged at the same time, such as articular cartilage, meniscus and bone bruising. The usual knee recon waits until 14-16 weeks post op to start light running, so this allows the damaged structures to heal somewhat in that time period.

So, will we see an increase incidence of knee arthritis in these LARS knees in 5-10 years time? .