Frequently asked questions
This section aims to answer many questions that patients considering LARS soft tissue reconstruction may have, as comprehensively as possible. However it is not designed to replace advice from your physician or surgeon and you should always seek detailed advice from a qualified medical practitioner before making any decisions about whether LARS is an appropriate treatment for you.
What is LARS?- Why is reconstruction necessary after rupture?
- How does LARS differ from earlier synthetic ligaments?
- How are LARS ligaments used?
- Are there any prerequisites for using LARS?
- What are the implications of native tissue grafts?
- Am I too young for a LARS ligament?
- Can a LARS ligament fail and what happens if it does?
- What long-term results and experience exist with LARS?
- What should I expect from surgery?
- How important is physical therapy?
- Can you return to sport with a LARS ligament?
- What is synovitis and can it occur with LARS?
- What is osteoarthritis and can it occur with LARS?
LARS offers a wide range of sterile, artificial ligaments, specially designed to provide a scaffold for the repair of native soft tissues in the body after rupture. LARS ligaments come in a variety of shapes, sizes and strengths to suit the many applications that they are used for. They are made of polyethylene terephthalate (PET) and are designed to remain in the human body after surgery.
There are over 500 different types of PETs commercially available, each with their own specific physical and mechanical characteristics. LARS ligaments use a PET which has been specially selected because of its characteristics for various ligament applications. In contrast to previous generation synthetic ligaments, LARS are extensively treated to remove residual processing aids which were found to inhibit healing of soft tissue. This has resulted in a ligament which is highly biocompatible1,2,3 with native tissues in the body.
2. Why is reconstruction necessary after rupture?
Tendon and ligament reconstruction is usually performed to restore stability, range of motion and proper function (biomechanics) to an affected joint, to minimise the possibility of future osteoarthritic changes or other degenerative processes. Restoring function as early as possible allows patients to return to their daily activities and to an active lifestyle, minimising pain and muscular wasting, known as ‘atrophy’.
3. How does LARS differ from earlier synthetic ligaments?
Synthetic ligaments have been used since the early 1980s with varying levels of success. They have been made from different materials and in different structures.
Knowledge of how joints work has improved considerably over the last 20-30 years, providing a greater insight into how native soft tissues work and how they should be repaired. We have learned how soft tissues, bony structures and muscles interact with each other to work efficiently and avoid future damage to the joint.
LARS ligaments were designed by a team of researchers and engineers including French surgeon, Professor Jacques-Philippe Laboureau. They were first implanted in Europe in 1992 and are the result of many years of elaborate research. They are designed to mimic the natural ligaments and tendons as closely as possible when implanted and to support your body’s natural healing mechanisms.
To give an example, the bending and straightening of the knee cause the cruciate ligaments to twist – both the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). Twisting produces torsional forces which place specific demands on any type of graft. LARS intra-articular ligaments (inside the joint) have a section of ‘free fibres’. These allow maximum resistance to rupture and shearing during normal movement of the knee, withstanding these forces and mimicking the function of the native ACL and PCL. The weave pattern of the woven sections that will be implanted into the bony tissues also provides strength and resists elongation of the ligament.
LARS ligaments are designed in a variety of sizes and strengths to support the soft tissues that have been damaged. Your surgeon will select the ligament that is best for your personal situation.
4. How are LARS ligaments used?
Recent research has found that while some tendons and ligaments have a natural healing response after rupture, others do not repair themselves. In the case of the ACL, where the ligament generally does not re-attach, this is not because the remnant ACL stumps cannot rebuild, but rather they are unable to continue the healing process without support4,5,6,7,8,9. In this application, the LARS ligament acts as a trellis for the native ACL stumps to regrow along.
While this process is occurring, the LARS ligament takes the strain that an ACL would normally take, preventing the new ligament from being damaged. As the new ligament develops, it envelops the LARS ligament10,11. Once completely healed, the native ACL will take over its normal function.
With a native tissue graft (usually either from the hamstrings or patellar tendons) the reconstruction philosophy is somewhat different. Although the implantation of LARS and native tissue grafts are similar, the native tissue grafts do not behave in the way that a LARS ligament does. After transplantation, the tendon graft undergoes a period of remodelling to transform from tendon to a functional ligament.
This process, which usually takes between 6-9 months, has been shown to take up to 24 months in some instances12, during which time the graft reduces in strength and is susceptible to possible elongation13. Elongation can reduce the functionality of both the ligament and the joint. In contrast, LARS provides immediate stability while the original ACL tissue regrows along the supporting LARS ligament.
LARS ligaments can also be used to support and strengthen native tissue grafts (known as augmentation). When native tissues are harvested from the body, they may be too short or small to be effectively used as a graft for an ACL reconstruction or in other applications. The use of a LARS ligament to ‘augment’ a hamstring or patella tendon graft can add length and strength to a graft14, but also protects the transplanted soft tissue during the re-modelling phase. During this phase, the graft is at its weakest and is susceptible to irreparable elongation and/or early breakage, which can result in a dysfunctional joint.
In tears of the Achilles tendon or rotator cuff, where treatment is not sought quickly, the remnant soft tissue stumps can shrink or retract significantly. Your surgeon may attempt to pull the two stumps together to repair the tear, but if the retraction is too great, the stumps cannot be joined and a LARS can be used to bridge the gap. This will again allow for soft tissue to heal across the LARS ligament.
5. Are there any prerequisites for using LARS?
The main requirement for LARS is that there is healthy remnant tissue, with a good blood supply, from which new tendon or ligament can grow. In acute rupture of the anterior cruciate ligament (ACL), it is rare that the health of the stump is too poor to continue healing. However in older chronic injuries, where there is often badly degraded soft tissues and scar tissue without any blood supply, or in the rupture of previously repaired soft tissues where the remnant may have been removed, soft tissue should be transplanted in addition to the use of a LARS ligament.
6. What are the implications of native tissue grafts?
Native tissue grafts involve the harvest of healthy native tissue usually from the hamstrings or patella tendons to reconstruct ruptured soft tissues. Although these techniques have been used successfully for many years, there are several complications associated with either surgery which can often last for a long time.
Hamstring graft recipients can experience loss of knee flexor and rotational strength, habitual muscle injuries and weaker-grown hamstrings15,16,17,18. A recent study in Melbourne, Australia, showed that strength deficits of between 3-27% were reported up to three years after grafts were taken19. The same study also showed over 50% of patients still suffered pain at the site of the graft harvest after three years postoperatively.
Patella tendon graft recipients often report anterior knee pain, extension mechanism and range deficits and loss of sensitivity20. Even after ten years post-harvest, one study reported over 24% of patients receiving patella grafts experienced some numbness, irritation or tenderness at the harvest site21. The use of a patellar tendon autograft also appears to lead to an increased osteoarthris rate32.
7. Am I too young for a LARS ligament?
It has been reported in the media that LARS ligaments are more suitable for older athletes. While older athletes may have more time pressure to return to sport quickly and also ‘less to lose’, early return to sport is not the only benefit that a LARS reconstruction offers.
Recent studies22 have shown that healing responses diminish with age, suggesting that younger patients would benefit more from a soft tissue reconstruction using LARS than older patients. In addition to this, by using the remnant stumps of soft tissue to regrow a ligament or tendon, the harvesting of soft tissue is avoided. This minimises possible complications after surgery, doesn’t compromise healthy soft tissue structures should there be issues in the future and has not been shown to cause irreparable or devastating changes to the joint.|
8. Can a LARS ligament fail and what happens if it does?
Like any native tissue or allograft, LARS reconstructions can fail. Studies generally indicate a failure rate in LARS ACL reconstructions of between 0-7% over a period of up to eight years follow-up23,24,25,26,27,28,29.
A landmark long-term Australian study on patella and hamstring tendon grafts30,31 reported patella tendon reconstruction rupture rates of 3% at five years, 4% at seven years and 8% at 15 years32, and hamstring tendon ruptures of 8% at five years and 9% at seven years. The same surgeon recently reported a hamstring failure rate of 16% and a patellar tendon failure rate of 8% after 15 years33. These mid-term (3-7 year) results are comparable with LARS rupture rates over the same timeframes. There is no evidence available that long-term LARS results are worse than those for either hamstring or patellar tendon reconstructions.
Breakage of a LARS most commonly occurs due to trauma, e.g. heavy impacts to the knee, motor vehicle accidents, etc, where the bones making up the joints may otherwise be damaged if rupture did not occur. This occurs just as it would for the original ACL tissue or any other grafted ACL.
If a LARS ligament fails, it can be removed and revised with another LARS ligament alone if healthy tissue remnants remain. It can also be replaced by a LARS with a soft tissue graft if the remnant tissue is absent or of poor quality or it can be revised with a hamstring or patella tendon, provided that the tissues have not been previously harvested. LARS should not be considered as a last resort, but rather as a way to keep other options open for the future.
9. What long-term results and experience exist with LARS?
During its 18 year-long clinical history, LARS reconstructions have been clinically proven to be reliable procedures. Developed in France in the 1980s, by French orthopaedic surgeon, Professor Jacques-Philippe Laboureau, and first implanted in 1992 by the pioneer himself in Dijon, France, LARS is now widely used and accepted throughout Europe, the United Kingdom, Canada, South Africa and Australia. Approval to use LARS in the USA has not been sought to date.
Over the past 18 years more than 60,000 LARS ligaments have been implanted worldwide, with more than 30,000 LARS ligaments used for ACL alone. LARS has been used with great success and with very high patient satisfaction in a large number of applications including, but not limited to, knee reconstructions involving the anterior cruciate ligament (ACL); posterior cruciate ligament (PCL); posterolateral corner (PLC); medial collateral ligament (MCL); and/or lateral collateral ligament (LCL) structures; patella realignments; gluteal repairs; as well as acromioclavicular joint and rotator cuff repairs in the shoulder. Studies report ‘good’ to ‘excellent’ outcomes in greater than 95% of LARS recipients14,23,24,25,26,27,28,29. Unlike previous generations of synthetic ligaments, no increased incidences of adverse body reactions have been reported with LARS surgery.
10. What should I expect from surgery?
If your surgeon recommends LARS for your reconstruction, you will need to have an operation – usually performed under general anaesthetic. Your surgeon will provide specific information about your type of surgery.
Most procedures use arthroscopy or minimally invasive techniques to implant LARS ligaments. The technique used to repair the tendon or ligament will dictate your rehabilitation strategy and period.
Once the anaesthetic wears off, you may be encouraged to walk the day of the operation. Depending on how the procedure is carried out, you might require crutches for a short time with some procedures. Your surgeon will provide you with specific information about your rehabilitation and follow-up visits.
If your surgeon is able to use your tendon or ligament remnants in conjunction with the LARS, you may have a shorter recovery time to return to daily activities and sports than if you need to have a native tissue graft taken23,25, as there will not be additional trauma to the surrounding musculature29 from the harvesting of additional tissue for transplantation. The speed of your recovery will be dependent upon how your tendon or ligament heals and how quickly your proprioception returns. Proprioception is the ability to know the location of your limbs in space and is a function of the central nervous system, although specific cells in muscles, tendons and ligaments also contribute to this.
11. How important is physical therapy?
As LARS ligaments provide immediate stability and strength, you may be able to progress rehabilitation activities quicker than with a native tissue graft. Some procedures, such as rotator cuff repair, may still require a prolonged immobilisation period to assist with wound healing. Your surgeon and physical therapist will advise you on your best rehabilitation strategy.
Although the LARS ligament is strong from the moment it is implanted, it is vital that you work diligently with your physiotherapist to reduce any swelling, regain full range of motion and to develop strength and proprioception. Restoration of proprioception is often the limiting factor with regard to how fast you can return to sporting activity.
Rehabilitation is extremely important to increase your likelihood of a successful outcome. It has been shown that the adherence to rehabilitation programmes may be the most significant indicator of outcome in reconstructive surgeries34. The speed of the rehabilitation process will differ between individuals due to differing levels of commitment, compliance and an individual’s physiological and psychological condition.
12. Can I return to sport with a LARS ligament?
A return to sport and daily living activities is the primary goal of any reconstructive surgery. As part of your rehabilitation programme after LARS surgery, you will be encouraged to return to sporting activities.
A recent review encompassing 48 studies published after 2000, including over 5700 patients receiving a traditional anterior cruciate ligament (ACL) graft, showed that 85% of patients returned to sport after ACL reconstruction, but only 64% returned to their pre-injury level and 56% returned to competitive sport35. A recent study of LARS ACL reconstructions showed a return to sport of 100%, with 82% returning to their pre-injury level of sport14.
Elite level competitive athletes do incur an increased level of risk of re-rupture with a previously reconstructed knee. The 2009 AFL injury report36 showed an average rerupture rate of reconstructed ACLs using traditional means of 15% (range 0-27%) after re-operation. This rate is much higher than quoted previously for the general population.
While no studies have been specifically targeted at elite level athletes with LARS ligament reconstruction, two studies25,27 reported on reconstructions on professional athletes with LARS, all of whom returned to sport after reconstruction. With that said, it is expected that this increased risk of rupture in the elite athlete population could continue to exist due to the highly demanding nature of competitive sporting activity.
13. What is synovitis and can it occur with LARS?
Synovitis is the inflammation of the lining of the joint capsule (found in synovial joints such as the knee). Synovitis is most commonly associated with severe pain and swelling of a joint and a significant decrease of joint function. It may occur for a number of reasons including trauma, joint instability, rheumatoid arthritis, genetic pre-disposition or there may be no known cause. Synovitis can occur in almost any joint in the body.
Synovitis, caused by exposure to earlier types of synthetic ligaments, occurred only where a synthetic ligament was exposed to the synovial fluid. The only applications where this occurs are the cruciate ligaments in the knee and the rotator cuff of the shoulder. To date, only one patient in 17 intra-articular studies14,23,24,25,26,27,28,29 of over 900 patients with LARS reconstructions has reported mild synovitis, which was easily resolved with subsequent treatment. Many earlier synthetic ligaments were associated with increased incidence of synovitis due to poor material choice and/or understanding of stresses and strains placed on the ligaments. LARS has been designed to mimic the body’s natural movement through soft tissues; moreover the LARS material has been selected and treated to be biocompatible37.
For applications where there is no exposure to synovial fluid, e.g. lateral collateral ligaments (LCLs) or medial collateral ligaments (MCLs), Achilles tendon reconstructions, etc, there is no possibility of development of synovitis due to synthetic ligament exposure.
14. What is osteoarthritis and can it occur with LARS?
Osteoarthritis is a degenerative disease that sees the degeneration of cartilage in the joints. Severe osteoarthritic changes often lead to total joint replacements with increasing time. Unfortunately osteoarthritis is associated with many soft tissue ruptures, including anterior cruciate ligaments (ACLs), posterior cruciate ligaments (PCLs) and large scale rotator cuff tears.
ACL studies have shown that there may be no correlation between reconstruction and protection from degenerative changes. Reports of osteoarthritis vary widely in studies of native tissue reconstructions and have been as high as 70%38.
No studies to date have shown an increased incidence of osteoarthritis in LARS reconstructed intra-articular soft tissues. To date, two patients in 17 intra-articular studies14,23,24,25,26,27,28,29 of over 900 patients with LARS reconstructions were reported to have mild radiographic degenerative changes.
References:
1.Yu SB, Dong QR, Wang YB, Zuo ZN, Li DG. Histological characteristics and ultrastructure of polyethylene terephthalate LARS ligament following the reconstruction of anterior cruciate ligament in rabbits. Zhongguo Zuzhi Gongcheng Yanjiuyu Linchuang Kangfu, 2008;12(36):7061-7066.
2. Trieb K, Blahovec H, Brand G, Sabeti M, Dominkus M, Kotz R. In vivo and in vitro cellular growth into a new generation of artificial ligaments. European Surgical Research, 2004;36:148-151.
3. Tarbrizian M, Leroy-Gallisot A, Yahia L. Technical Report: Evaluation of Synthetic LARS knee ligaments. Biomechanics and Biomaterials Research Group. École Polytechnique de Montréal, pp. 1-34.
4. Murray MM, Spector M. Fibroblast distribution in the anteromedial bundle of the human anterior cruciate ligament: the presence of alpha-smooth muscle actin-positive cells. Journal of Orthopaedic Research, 1999;17: 18-27.
5. Murray MM, Martin SD, Spector M. Migration of cells from human anterior cruciate ligament explants into collagen-glycosaminoglycan regeneration templates in vitro. Biomaterials, 2000;22:2293-2402.
6. Murray MM. Current status and potential for primary ACL repair. Clinical Sports Medicine, 2009; 28(1):51-61.
7. Murray MM, Spindler KP, Ballard P, Welch TP, Zurakowski D, Nanney LB. Enhanced Histologic repair in a central wound in the anterior cruciate ligament with a collagen–platelet-rich plasma scaffold. Published online 5 April 2007 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jor.20367.
8. Steiner ME, Murray MM, Rodeo SA. Strategies to improve anterior cruciate ligament healing and graft placement. American Journal of Sports Medicine, 2008;36(1):176-189.
9. Spindler KP, Murray MM, Devin C, Nanney LB, Davidson JM. The central ACL defect as a model for failure of intra-articular healing. Published online 6 January 2006 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jor.20074.
10. Trieb K, Blahovec H, Brand G, Sabeti M, Dominkus M, Kotz R. In Vivo and in vitro cellular ingrowth in a new generation of artificial ligaments. European Surgical Research, 2004;36:148-151.
11. Shao-bin Y, Qi-rong D, Ya-bin W, Zhong-nan Z, De-gui L. Histological characteristics of an ultrastructure of polyethylene terephthalate LARS ligament following the reconstruction of anterior cruciate ligament in rabbits. Zhongguo Zuzhi Gongcheng Yanijuyu Linchuang Kangfu, 2008;12(36):7061-7066.
12. Janssen RP, van der Wijk J, Fiedler A, Schmidt T, Sala HA, Scheffler SU. Remodelling of human hamstring autografts after anterior cruciate ligament reconstruction.Knee Surg Sports TraumatolArthrosc. 2011 Feb 4.[Epub ahead of print].
13. Noyes FR, Butler DL, Grood ES, Zernicke RF, Hefzy S. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J. Bone Joint Surg Am. 1984;66:344-352.
14. Hamido F, Misfer AK, Al Harran H, Khadrawe TA, Soliman A, Talaat A, Awad A, Khairat S. The use of the LARS artificial ligament to augment a short or undersized ACL hamstrings tendon graft. [epub ahead of print] The Knee (2010), doi:10.1016/j.knee.2010.09.003
15. Armour T, Forwell L, Litchfield R, Kirkley A, Amendola N, Fowler PJ. Isokinetic evaluation of internal/external tibial rotation strength after the use of hamstring tendons for anterior cruciate ligament reconstruction. American Journal of Sports Medicine, 2004;32:1639-1643.
16. Eriksson K, Hamberg, P, et al. Semitendinosus muscle in anterior cruciate ligament surgery: Morphology and function. Arthroscopy, 2001;17(8): 808-817.
17. Papandrea P, Vulpiani, M, et al. Regeneration of the semitendinosis tendon harvested for anterior cruciate ligament reconstruction. Evaluation using ultrasonogrphy. American Journal of Sports Medicine, 2000;28:556-561.
18. Feller JA, Webster KE, Gavin B. Early post-operative morbidity following anterior cruciate ligament reconstruction: patellar tendon versus hamstring graft. Knee Surgery, Sports Traumatology, Arthroscopy, 2001; 9:260–266.
19. Arden CL, Webster KE, Taylor NF, Ph.D.,Feller JA. Hamstring Strength Recovery After Hamstring Tendon Harvest for Anterior Cruciate Ligament Reconstruction: A Comparison Between Graft Types. Arthroscopy: The Journal of Arthroscopic and Related Surgery, 2010; 26(4):462-469.
20. Busam ML, Provencher MT, Bach BR. Complications of anterior cruciate ligament reconstruction with bone-patellar tendon-bone constructs: Care and prevention. American Journal of Sports Medicine, 2008;36: 379-394.
21. Pinczewski LA, Lyman J, Salmon LJ, Russell VJ, Roe J, Linklater J. A 10 year comparison of anterior cruciate ligament reconstructions with hamstring tendon and patella tendon autograft: a controlled, prospective trial. American Journal of Sports Medicine, 2007;35(4):564-574.
22. Vavken P, Murray MM. The Potential for Primary Repair of the ACL. Sports Medicine and Arthroscopy Review. 2011; 19(1):44-49.
23. Nau T, Lavoie P, Duval N. A new generation of artificial ligaments in reconstruction of the anterior cruciate ligament. Journal of Joint and Bone Surgery, 2002; 84(B):356-360.
24. Gao et al. Anterior cruciate ligament reconstruction with LARS artificial ligament: a multicentre study with 3 to 5 year follow up. Arthroscopy: The Journal of Arthroscopic and Related Surgery, 2010;26(4):515-523.
25. Huang JM, Wang Q, Wang ZM, Kang YF. Cruciate ligament reconstruction using the LARS artificial for reconstruction using LARS artificial ligaments under arthroscopy: 81 cases report. Chinese Medical Journal, 2010;123(2):160-164.
26. Lui ZT, Zhang XL, Jiang Y. Four-strand hamstring tendon autograft versus LARS artificial ligament for anterior cruciate ligament reconstruction. International Orthopaedics, 2010;34(1):45- 49.
27. Cerulli G, Caraffa A, Antenucci R, Antinolfi P. Illegamentoartificiale. GiornaleItaliano di Ortopedia e Traumatologia, 2007;33(1):238-242.
28. Lavoie P, Fletcher J, Duval N. Patient satisfaction as related to knee stability and objective findings after ACL reconstruction using the LARS artificial ligament. The Knee, 2000;7:157-163.
29. Dericks G. Ligament advanced reinforcement system anterior cruciate ligament reconstruction. Operative Techniques in Sports Medicine, 1995;3(3):187-205.
30. Pinczewski LA, Deehan DJ, Salmon LJ, Russell VJ, Clingeleffer A. A Five-Year Comparison of Patellar Tendon Versus Four-Strand Hamstring Tendon Autograft for Arthroscopic Reconstruction of the Anterior Cruciate Ligament. American Journal of Sports Medicine, 2002;30: 523-536.
31. Roe J, Pinczewski LA, Russell VJ, Salmon LJ, Kawamata T, Chew M. A 7-Year Follow-up of Patellar Tendon and Hamstring Tendon Grafts for Arthroscopic Anterior Cruciate Ligament Reconstruction: Differences and Similarities. American Journal of Sports Medicine, 2005; 33:1337 - 1345 .
32. Hui C, Salmon LJ, Kok A, Maeno S, Linklater J, Pinczewski LA. Fifteen-year outcome of endoscopic anterior cruciate ligament reconstruction with patellar tendon autograft for “isolated” anterior cruciate ligament tear. American Journal of Sports Medicine, 2011, 39(1):89-98.
33. Pinczewski LA, et al. Clinical results and risk factors for reinjury 15 years after ACL reconstruction. A prospective study of hamstring and patellar tendon graphs. Paper 9584. Presented at the 2011 American Orthopaedic Society for Sports Medicine Specialty Day. Feb. 19, 2011.
34. Richter M, Bosch U, Wippermann B, Hofmann A, Krettek C. Comparison of surgical repair or reconstruction of the cruciate ligaments versus nonsurgical treatment in patients with traumatic knee dislocations. American Journal of Sports Medicine, 2002;30(5):718-27.
35. Arden CL, Webster KE, Taylor NF, Feller JA. Return to sport following anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis of the state of play. British Journal Sports Medicine, 2011 Mar 11. [Epub ahead of print]
36. 2009 AFL Injury report. Cited April 2011. http://www.afl.com.au/injury%20report/tabid/13706/default.aspx
37. LARS Material Properties brochure
38. Von Porat A, Roos EM, Roos H. High prevalence of osteoarthritis 14 years after an anterior cruciate ligament tear in male soccer players: a study of radiographic and patient relevant outcomes. Annals of Rheumatic Disease, 2004;63:269-273.
Important: The information and guidance provided here is general in nature and should not be considered as medical advice in any way. You should always seek detailed advice from a qualified medical practitioner.
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