Introduction
The Ligament Augmentation and Reconstruction System or Advanced Ligament Augmentation System (LARS) is an artificial ligament used as a synthetic graft for ACL and PCL reconstruction as well as knee extensor ankle ligament and shoulder and hip tendon reconstruction [1].
In ACL injuries, the LARS ligament can only be used to hold together the stumps of the ruptured ACL[1] Therefore, if there is no tissue remnant at one or both ligament sites, the LARS ligament can only be used as a scaffold to reinforce the autograft Transplantation or allograft reconstruction. However by making Using the remaining tissue, the LARS ligament promotes a faster healing process and earlier return of proprioception, and promotes ingrowth of natural tissue into the synthetic ligament.
The LARS device is made of polyethylene terephthalate (PET), which is processed after manufacture to remove the fat emulsion needed for the processing stage, but which, if not removed, can lead to reactive synovitis and immune responses in humans [2].
It consists of two sections,
- the intra-articular section.
- the intra-osseous section.
Previous synthetic ligaments have struggled with high rates of synovitis due to the release of particulates into the joint due to ligament wear. The new LARS system attempts to overcome this problem by combining two bundles of free longitudinal fibers intra- and intra-articularly Part of the warp-knitted fibers in the bone [1]. The longitudinal fibers are rotated 90° and clockwise or counterclockwise to reconstruct the right or left knee ACL respectively to replicate the native ACL and help it resist assumed torsional and shear forces Caused wear leading to synovitis in early designs [3]. Furthermore, the free orientation of longitudinal fibers aims to promote osteoblast and fibroblast ingrowth and resist fatigue during flexion and extension. The fibers are also porous to allow further The fibroblasts grow ingrowth with the aim that the newly formed collagen will eventually overtake the synthetic ligament [3][4].
LARS ligaments come in many different sizes and designs, depending on the intended use and the surgical technique used to implant the device. Traditional LARS ligaments can withstand forces of 3500N to 5000N, while short ligaments can withstand forces of 3000N, suspensory ligaments The fixation ligaments can withstand forces between 2700N and 4720N [1].
It is important to note that while the LARS ligament has been marketed since 1992, it is not approved in all countries, including the United States. However, it is available in the UK, France, Germany, Canada, China, and Australia. Numerous studies have been conducted on the use of LARS in China High levels of success have been achieved in older populations [4]. It is also particularly famous in Australia, where it receives national attention as it is often used by high-level athletes. However, it has recently gained notoriety, and many surgeons have become wary of the risk Failure and resulting synovitis and premature arthritis [5].
Advantages of LARS
- No functional impairment or morbidity from the donor site used in autologous transplantation
- Shorter return to function
- Mimics natural ACL structure and orientation
- Reduces shearing forces on the implant
- Porosity encourages tissue ingrowth
- Low cases of synovitis reported
Disadvantages
- Residual postoperative laxity persists
- Requires reconstruction using tissue remnants of the ACL
- Lack of long-term studies and mixed results based on current knowledge base [6][7]
Surgical Procedure
Unlike autografts, which can replace the entire ligament, the LARS system can only be used when there is tissue remnant of the original ligament. [1] Following the decision to use the LARS ligament for reconstruction, preoperative planning is essential
Imaging techniques are used first to confirm the clinical diagnosis and identify anatomical femoral and tibial landmarks that will be used to orient the surgeon and determine the need for notchplasty [1].
There are four LARS device insertion techniques:
- The traditional technique.
- The independent AM portal technique.
- The short ligament technique is designed to reduce injury to the quadriceps by not requiring pulling the LARS ligament through the femoral tunnel into the soft tissue.
- The suspension fixation technique is an alternative to normal screw fixation and relies on buckle-in and cross-pin femoral suspension [1].
Detailed instructions for the different surgical procedures can be found here:
LARS ligaments can also be used to augment autograft or allograft reconstructions. This is useful when harvested grafts are weak and/or undersized. The synthetic ligament acts as a central core around which the biological ligament wraps. The syndesmotic ligament can then be secured using any of the following methods Interference screw or suspension fixation [1].
The following video is an animation of ACL reconstruction using the LARS ligament
Clinically Relevant Anatomy
See:
Anterior Cruciate Ligament (ACL)
Anterior Cruciate Ligament (ACL) – Structure and Biomechanical Properties
Rehabilitation
As with other forms of ACL reconstruction, rehabilitation depends on other pathologies of the knee as well as individual patient characteristics and requirements. However, studies have shown that those who had LARS reconstruction were able to return to sport earlier than those who had LARS reconstruction with other forms of reconstruction [3] [7] [8]
There is limited information available on rehabilitation programs and these details are often missing in LARS ligament studies [9]. The following protocol is recommended:[1]
- No post-op bracing or immobilisation.
- Full weight bearing and mobilization and isometric quadriceps exercises were initiated the day after surgery to restore full extension.
- 90° flexion should be achieved after 7-10 days.
- Resumption of driving should be at the discretion of the patient and surgeon.
- Return to work will depend on the type of work and the individual patient’s recovery time.
- Patients can usually start jogging 6-9 weeks after surgery.
- Participation in competitive sports depends on the patient’s individual recovery and should only be recommended after the patient has regained full proprioception. Generally, this may happen after 3-4 months.
Another study by Hamido et al compared quadruple hamstring grafts (4-SHG) and 4-SHG augmented with LARS ligaments in ACL reconstruction and used the same rehabilitation protocol for both groups. They set out the following timeline in their study. [10]
- Begin quadriceps isometric closed kinetic chain exercises and straight leg raises as early as possible.
- Knee flexion was gradually increased from 45°, and the flexion and extension were completed within the first week.
- Crutches were used for 3 weeks.
- Static stepping was allowed for balance during the first few weeks, with full weight bearing after 4 weeks postoperatively.
- Cycling is permitted for 4-5 weeks postoperatively.
- Patients typically returned to normal daily activities within four months and were allowed to participate in noncompetitive sports, which did not include spinning or recreational skiing, and resumed physical activity after six months.
Evidence from Research
Compared with biological alternatives, synthetic ligaments have historically failed, so surgeons have been reluctant to propose this next-generation treatment. This results in a shallow research base on LARS ligament outcomes, with fewer studies focusing on the LARS ligament Long-term follow-up. Even after analyzing the available data, it is difficult to make a definitive decision on the effectiveness of the LARS ligament, as studies have found it to be either a reliable alternative in many cases, or a biological replacement that still does not achieve its high efficiency product equipment failure and synovitis of the joints.
Below is a summary of the many available studies, including some systematic reviews of multiple studies.
- A study by Norsworthy [11] examined the outcomes of 54 patients with a mean age of 36.5 years who underwent LARS ligament reconstruction either at their own request or because of the need for a quick return to activity. After at least 5 years of follow-up, 17 patients had surgically confirmed failure of LARS The incidence rate of ligament was 31.5%. They found that in fewer than 50% of all failure cases, the LARS ligament had native tissue ingrowth, and seven patients had overt signs of synovitis. Among patients without a malfunctioning device, the mean IKDC (|International Knee Documentation Committee) score was 86.2, there were no statistically significant differences in ROM and anterior laxity recorded in left-right comparisons.
- In a comparative study between the LARS ligament and another synthetic ligament called ABC pure polyester ligament, Iliadis et al. [12] found a 31% rupture rate of the LARS ligament after a mean follow-up of 9.5 years. More than 80% of fractures are caused by further knee injuries in 68% Occurs during physical activity. However, for those with intact ligaments, the study reported a mean Lysholm score of 90, a mean IKDC score of 90, and positive scores on other measurement scales. The study also reported that 60 percent of these patients returned to their pre-injury activity levels. This The average age of participants in this study was 26.1 years, and all participants were male.
- Mascarenhas and MacDonald [13] discuss the benefits and outcomes of various synthetic ligaments and use a study by Lavoie et al. Among other things, the LARS ligament is checked. Lavoie examined 47 patients who underwent ACL reconstruction using the LARS ligament. After an average of 21.9 months On follow-up, 38 patients had chronic ACL rupture and 9 patients had acute or subacute rupture.
- Two studies by Parchi et al. [14] examined the outcome of the LARS ligament with long-term follow-up. The first study recorded a 92.3% global positive result with only one graft failure (1/26) and no cases of knee synovitis or infection. The study concluded that the LARS ligament is For elderly patients requiring rapid functional recovery (9). In the second study, 26 patients were all over the age of 30 and needed to return to exercise as soon as possible. Patients returned to activity after an average of four months and reported overall positive outcomes. Four (4/26) Grafting Failures were documented, with the majority of patients scoring “good” or “excellent” on the ROM knee laxity KOOS (Knee Injury Osteoarthritis Outcome Score) and the Cincinnati Knee Rating Scale [14]. Parchi believes that one reason for the discrepancies in the LARS findings may be Differences in graft fixation methods. However, they also point out that research is underway to improve immobilization methods using nanotechnology. [14]
- A systematic review by Newman et al. [3] examined the results of nine studies on the use of LARS ligaments for ACL reconstruction. They found a failure rate of only 2.5% in 675 LARS uses, with many failures attributed to technical errors in bone tunnel placement. They also found that a Successful return to play two to six months after surgery. Furthermore, only two cases of synovitis were documented. However, it is important to note that Newman determined that the methodological quality of the studies they reviewed was poor, so this should be kept in mind when conducting the review Analyze the results.
- A six-week follow-up study by Krupa et al. [15] compared the preoperative and postoperative results of the drawer test before the Lachman test and the pivot shift test in 20 men undergoing LARS ACL reconstruction. Most documented Lachman and anterior drawer postoperative outcomes were normal test and a negative pivot shift test. They also found that there was generally no difference in ROM between affected and uninvolved knees (14). However, this study was limited by the short-term nature of the follow-up.
- Finally, two studies by Hamido et al. [10][16] examined the use of the LARS ligament in combination with short or undersized hamstring tendons compared to quadruple hamstring autograft (4-SHG) ACL reconstruction . The first study in 2011 was conducted at the end of the 5-year follow-up The combination was found to be “useful, safe and satisfying . . . especially when early return to high levels of physical activity is required” [16]. A second study [10] also found that augmented ACL reconstruction was superior to 4-SHG only again after 5 years follow up. LARS augmentation was supported by IKDC KOOS Lysholm and Tegner scores, who also found significantly less anterior displacement than 4-SHG. [17]
Summary
If there is sufficient tissue remnant from the ruptured ACL, the LARS ligament can be used either as a free-standing synthetic ligament or as a scaffold to augment the use of other types of ligament grafts. It’s one of a growing number of attempts to improve failing synthetic ligaments Man-made devices of the past. There have been several iterations of the LARS device to accommodate many different scenarios in ACL reconstruction, but they all attempt to promote faster healing, faster proprioceptive return, and native tissue ingrowth into the reconstruction.
There are various reconstruction and augmentation techniques depending on the type of LARS ligament used and the requirements of the patient.
The rehabilitation plan for LARS reconstruction is similar to that for autograft and allograft surgery, but with an accelerated return to function. However, other joint and connective tissue lesions must be considered when designing and developing recovery and rehabilitation programs Timetable.
Studies of the reliability and effectiveness of LARS ligaments have produced wildly mixed data, with many studies producing contradictory results. Researchers who conduct systematic reviews often warn of methodological quality and scarcity of high-quality long-term studies Judging follow-up studies when using LARS ligaments in ACL injuries.
References
- ↑ Jump up to:1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Corin Group. ACL Augmentation and Reinforcement Surgical technique LARS ACLTM Contents [Internet]. Corin P; 2013 [cited 2020 Sep 11]. Available from: https://www.coringroup.com/assets/product-resources/LARS/Resources-Product-Literature-LARS-ACL-Surgical-Technique.pdf
- ↑ Corin Group. LARS TM ACL [Internet]. Corin P; 2010 [cited 2020 Sep 12]. Available from: https://www.coringroup.com/assets/product-resources/LARS/Resources-Product-Literature-LARS-ACL-Your-Questions-Answered.pdf
- ↑ Jump up to:3.0 3.1 3.2 3.3 Newman SDS, Atkinson HDE, Willis-Owen CA. Anterior cruciate ligament reconstruction with the ligament augmentation and reconstruction system: A systematic review [Internet]. Vol. 37, International Orthopaedics. Springer; 2013 [cited 2020 Sep 11]. p. 321–6. Available from: /pmc/articles/PMC3560896/?report=abstract
- ↑ Jump up to:4.0 4.1 Chen S, Chen T, Wan F, Jiang J, Feller JA. Synthetic ligaments for ACL reconstruction. In: Controversies in the Technical Aspects of ACL Reconstruction: An Evidence-Based Medicine Approach [Internet]. Springer Berlin Heidelberg; 2017 [cited 2020 Sep 13]. p. 333–41. Available from: https://link.springer.com/chapter/10.1007/978-3-662-52742-9_31
- ↑ Whatever happened to LARS? The miracle ACL surgery that was too good to be true – ABC News [Internet]. [cited 2020 Sep 11]. Available from: https://www.abc.net.au/news/2018-08-17/whatever-happened-to-lars-acl-the-miracle-cure-that-was-too-good/10129102
- ↑ Iliadis DP, Bourlos DN, Mastrokalos DS, Chronopoulos E, Babis GC. LARS Artificial Ligament Versus ABC Purely Polyester Ligament for Anterior Cruciate Ligament Reconstruction. Orthop J Sport Med [Internet]. 2016 Jun 23 [cited 2020 Sep 11];4(6):2325967116653359. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27453894
- ↑ Jump up to:7.0 7.1 Parchi PD, Gianluca C, Dolfi L, Baluganti A, Piolanti N, Chiellini F, et al. Anterior cruciate ligament reconstruction with LARSTM artificial ligament results at a mean follow-up of eight years. Int Orthop [Internet]. 2013 Aug 1 [cited 2020 Sep 12];37(8):1567–74. Available from: https://pubmed.ncbi.nlm.nih.gov/23812539/
- ↑ Mascarenhas R, MacDonald PB. Anterior cruciate ligament reconstruction: A look at prosthetics – Past, present and possible future [Internet]. Vol. 11, McGill Journal of Medicine. McGill University; 2008 [cited 2020 Sep 12]. p. 29–37. Available from: /pmc/articles/PMC2322926/?report=abstract
- ↑ Machotka Z, Scarborough I, Duncan W, Kumar S, Perraton L. Anterior cruciate ligament repair with LARS (ligament advanced reinforcement system): A systematic review [Internet]. Vol. 2, Sports Medicine, Arthroscopy, Rehabilitation, Therapy and Technology. BioMed Central; 2010 [cited 2020 Sep 12]. p. 1–10. Available from: https://link.springer.com/articles/10.1186/1758-2555-2-29
- ↑ Jump up to:10.0 10.1 10.2 Hamido F, Al Harran H, Al Misfer AR, El Khadrawe T, Morsy MG, Talaat A, et al. Augmented short undersized hamstring tendon graft with LARS® artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: Preliminary results. Orthop Traumatol Surg Res. 2015 Sep 1;101(5):535–8.
- ↑ Norsworthy CJ, Tulloch SJ, Devitt BM, Porter TJ, Hartwig TR, Klemm HJ. My experience with the LARS ACL device at minimum 5 year follow up. 2017 ISAKOS Congress, 7 June 2017 [cited 2020 Sep 11]. Available from: https://www.isakos.com/data/abstractpresentations/GenSes/2017-06-07/1530-SectionID1214/1550-Norsworthy/OUTLINE_EVENT_10096_MEMBER_ID_74440.pdf
- ↑ Iliadis DP, Bourlos DN, Mastrokalos DS, Chronopoulos E, Babis GC. LARS Artificial Ligament Versus ABC Purely Polyester Ligament for Anterior Cruciate Ligament Reconstruction. Orthop J Sport Med [Internet]. 2016 Jun 23 [cited 2020 Sep 11];4(6):2325967116653359. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27453894
- ↑ Mascarenhas R, MacDonald PB. Anterior cruciate ligament reconstruction: A look at prosthetics – Past, present and possible future [Internet]. Vol. 11, McGill Journal of Medicine. McGill University; 2008 [cited 2020 Sep 12]. p. 29–37. Available from: /pmc/articles/PMC2322926/?report=abstract
- ↑ Jump up to:14.0 14.1 14.2 Parchi PD, Ciapini G, Paglialunga C, Giuntoli M, Picece C, Chiellini F, et al. Anterior cruciate ligament reconstruction with LARS artificial ligament—clinical results after a long-term follow-up. Joints [Internet]. 2018 Jun 1 [cited 2020 Sep 12];6(2):75–9. Available from: /pmc/articles/PMC6059861/?report=abstract
- ↑ Krupa S, Królikowska A, Reichert P. Postoperative Knee Joint Stability Following Anterior Cruciate Ligament Reconstruction Using the Ligament Advanced Reinforcement System. Polim Med [Internet]. 2016 Jul 1 [cited 2020 Sep 12];46(2):155–61. Available from: https://pubmed.ncbi.nlm.nih.gov/28397456/
- ↑ Jump up to:16.0 16.1 Hamido F, Misfer AK, Al Harran H, Khadrawe TA, Soliman A, Talaat A, et al. The use of the LARS artificial ligament to augment a short or undersized ACL hamstrings tendon graft. Knee [Internet]. 2011 Dec 1 [cited 2020 Oct 20];18(6):373–8. Available from: http://www.thekneejournal.com/article/S0968016010001754/fulltext
- ↑ Wang XM, Ji G, Wang XM, Kang HJ, Wang F. Biological and Biomechanical Evaluation of Autologous Tendon Combined with Ligament Advanced Reinforcement System Artificial Ligament in a Rabbit Model of Anterior Cruciate Ligament Reconstruction. Orthop Surg. 2018 May 1 [cited 2020 Oct 20];10(2):144–51. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6594536/