Stitched together: LARS procedure and post-op ACL management

In our last newsletter we explored the anatomy of the anterolateral complex of the knee, reasons for the high rate of re-injury, and the rehab approach for conservative management. Most athletes, however, opt for surgical correction of an ACL tear. Contributor Chris Mallac highlights an alternative reconstruction method called a a Ligament Advanced Reinforcement System (LARS) procedure here.

The LARS is a synthetic graft that mimics the ACL through the alignment of its Polyethylene Terephthalate (PET) polyester fibers (see figure 1). The ninety-degree twist in the graft enables it to act more like the actual ACL, reducing shearing forces along the graft. The porous PET fibers function as a scaffolding, allowing tissue growth around and within it. This tissue ingrowth protects the graft from bony surfaces, helps anchor the graft to the residual ACL stump, and acts as a lubricant between the fibers, reducing mechanical wear. Polish researchers found the LARS graft provided excellent control of anterior translation and anterolateral knee movement six weeks after a LARS procedure (1). See Mallac's excellent review for more information about the procedure.

Figure 1: LARS scaffold consisting of an interosseous component of multiple parallel fibres of PET polyester

The advantage of the LARS procedure is the accelerated rehabilitation timeline, compared with traditional auto-grafts or allo-grafts (see table 1).  In part II of his series on the LARS procedures, Mallac divides the rehabilitation into four phases and outlines the appropriate rehab progression. He points out that the LARS procedure is not well studied and only available in select areas. Researchers in Italy followed 60 cases of patients 40 years and older, up to five years post LARS procedure and found them to have good results, with 31% returning to their previous lifestyle, no cases of re-injury, and 85.4% lacking signs of osteoarthritis five years after the procedure (2). Chinese researchers found similar results after a 7-year follow up with 91 patients who underwent a LARS procedure (3). The population in the Chinese study was only slightly younger, and 46 of the 91 patients returned to sport. However, socioeconomic changes had taken place within the population during the seven years after their surgery. Many of them had been students at the time of surgery and now had regular jobs. Only 5 of the study participants were limited in return to sport by continued knee dysfunction. These findings are consistent with the other studies that Mallac sites in part I, which found extremely low rates of re-injury, faster return to previous activities, and greater overall satisfaction with the post-operative results. Perhaps LARS will soon take hold as the standard of care for ACL repair.

Physical Milestone	LARS reconstructed knee	Autograft reconstructed knee
Protected weightbearing	Usually unnecessary	Dependent upon concomitant meniscal repair so this may be 6 weeks
Return to running	6 weeks post op	12 weeks post op
Return to training	9 weeks post op	16-20 weeks post op
Return to competition	14-16 weeks	24-52 weeks

References

1. Polim Med. 2016 Jul-Dec;46(2):155-161
2. Musculoskelet Surg. 2018 Apr;102(1):57-62
3. Medicine (Baltimore). 2017 Apr;96(14)