BRINGING SCIENCE TO TREATMENT
In part I of this two-part Masterclass article, Chris Mallac discusses in detail the postoperative rehab requirements following a unique ACL reconstruction method – a Ligament Advanced Reinforcement System (LARS) procedure.
Anterior cruciate ligament (ACL) rupture is a common injury suffered by many athletes in a variety of sports. It typically affects athletes involved in sports that require sharp deceleration and cutting/pivoting type movements such as all the football sports (soccer, rugby, AFL, NFL), basketball, netball, golf and tennis. It may also occur as the result of a direct blow to the outside of the knee, which causes a valgus knee collapse, imposing large tensile and torsional forces to both the medial collateral ligament (MCL) and ACL.
It has been estimated that 80% of all ligament reconstructions of the knee relate to the ACL1. It is accepted that ACL ruptures have poor intrinsic healing capabilities due to the fact that the ACL is enveloped by synovial fluid and lacks significant vascularisation2. This makes healing of this intra-articular ligament impossible due to the inability of the torn ligament to re-vascularize.
In many case therefore, this precipitates the need to reconstruct the ACL to achieve functional stability to withstand anteroposterior shear forces and to prevent rotational forces on the knee. This course of action will prevent any further meniscus breakdown, and early onset osteoarthritis due to the excessive shearing forces encountered by the ACL deficient knee3 4.
| Surgical options following ACL rupture |
|---|
| The decision to reconstruct the ACL is multifactorial and both the attending surgeon and patient discuss the need to reconstruct along the following paradigm(3): 1.Degree of symptoms – such as uncontrollable instability or giving way of the knee. 2. Age – younger athletes will have longer exposure to potentially joint damaging instability episodes. Therefore, early reconstruction to develop functional stability may be preferred even though there exists a lengthy rehabilitation process. An older athlete nearing retirement may prefer to take their chances rather than stepping out of training/competition for 9-12 months. 3. Participation in a pivoting sport such as football (all codes), netball, basketball, tennis, dance to name a few. 4. Level of activity – elite athletes are well advised to always have an ACL reconstructed whereas a recreational athlete may have different needs. 5. Failure or success of conservative management focusing on proprioception and hamstring strengthening |
Surgical techniques vary from surgeon to surgeon and from country to country. Indeed, it is not uncommon for two orthopaedic surgeons from the same sports medicine clinic to differ in their surgical choices. The options the surgeon has include:
The use of grafts falls into three different subtypes:
However synthetic grafts are now in their third generation and in the last 20 years the Ligament Advanced Reinforcement System (LARS) procedure has gained more popularity with orthopaedists10.
The LARS system was developed in France by a French surgeon called Professor JP Laboreau. This was developed over a lengthy period of time, finding a material and technique that would prevent the failure rates seen with other synthetic grafts, and to also avoid the morbidity seen with human tissue grafts involving the patella tendon and hamstring grafts.
LARS has been used successfully to reconstruct ACL ruptures in countries such as Australia, United Kingdom, France, Germany and Canada. However, the United States has still not approved the use of LARS in the USA, with the result that American athletes often seek surgical treatment in other countries.
A LARS is an intra-articular scaffold consisting of an interosseous component of multiple parallel fibres of Polyethylene Terephthalate (PET) polyester (see figure 1). The intra-articular segment is unique and different to other synthetic grafts in that it is twisted at 90 degree angles.
Biomechanically, this artificial ligament mimics the natural ligamentous structure of the ACL and this design reduces shearing forces by specifically orientating the intra-articular fibres either clockwise for right knees or counterclockwise for left knees. The porous nature of the PET fibres allow ingrowth from surrounding osseous tunnels and the remaining ACL stump. The ingrowth of the tissues into this scaffold gives the graft greater viscoelasticity and also protects against friction at the opening of the bony canal and between the fibres themselves11.
The LARS artificial ligament is sterilised and chemically treated to remove any potential machining residues. Also, the emulsion of fat enzymes that may prevent soft tissue ingrowth and the sterility reduces the risk of reactive synovitis and fibre breakdown associated with other synthetic grafts12 13 14.
In a LARS procedure, the synovial lining and the torn ACL fibres are left intact, whereas in other ACL reconstructive procedures the ACL is debrided to allow osseous tunnel drilling for the autologous graft. The osseous tunnels are positioned under image intensifier x-ray and this allows the torn ACL stump to remain. The proposed advantage of this technique is reduced trauma to the soft tissues of the knee and less surgical time15. The remaining ACL stump is anchored to the meshwork of the LARS to support it in an optimum position while healing. Figure 2 shows a summary of a typical LARS operative procedure.
*Image courtesy of Corin Group (www.coringroups.com)
Overall, the LARS surgical technique aims to maximise in-growth of the original ACL tissue, thus preserving some vascular and proprioceptive nerve supply. The biggest advantages of this procedure are immediate graft stability, reduced rehabilitation time and quicker return to pre-injury function. Over time, the existing ACL stump regrows into the matrix and eventually replaces the LARS. Therefore it is not used a stand- alone graft. It has been proposed that the benefit of the LARS procedure is that it allows early post-operative loading because the scaffold protects the ACL stump during its revascularisation phase, with less chance of post-operative breakdown16.
| Does LARS work? |
|---|
| Not many studies have effectively looked at the success rate of a LARS procedure in isolation, or LARS versus conventional ACL reconstructions. The following points summarise some of these findings: 1. In a large systematic review, it was found that in the data from 675 LARS ACL reconstructions, an overall failure rate of only 2.5% was found. Most of these were associated with iatrogenic failures such as placement of the osseous tunnels. Post-operative synovitis only occurred in one case, suggesting that these new LARS grafts solved the problem of postreconstructive synovitis with other synthetic grafts(12). 2. Another study with 220 patients reported a small number of infections (1.4%) and 9 ligament re-ruptures (4%). But 83% of patients reported returning to full sport by 6 months, with 41% returning by 4 months, which is significantly faster than traditional autologous grafts(8). 3. In a study that compared the standard hamstring graft versus the LARS procedure, it was found that the autologous hamstring graft group was protected over the first three months whereas in the LARS graft protection was not needed.Therefore, non-competitive sports activity was allowed within two months and return to full activity was allowed between three to four months. All patients returned to sport by six months with no failure rates. No differences in terms of functional outcomes were reported(12). 4. A retrospective study of LARS versus the 4-strand hamstring graft with a minimum follow up of 48 months demonstrated that the LARS group displayed significantly greater knee stability measures (IKDC scores, Lysholm scores and Tegner scores) compared to the hamstring graft group(14). 5. Two other studies found that LARS procedures resulted in faster return to sport with no failure rates over a 2-year(15) and 4-year period(16). |
The biggest potential problem faced when using a LARS procedure is the quality of the remaining ACL stump17. A viable stump is needed to allow new ligamentous tissue, and surgery needs to occur as soon as possible after injury to preserve the native ACL stump18. Therefore, the LARS reconstruction may be best suited to patients with acute ruptures who possess a viable cruciate stump. This allows the ligamentous and neurovascular tissues to regenerate along the synthetic scaffold. Furthermore, placement and tensioning of the LARS is crucial to prevent failure, emphasising the need for an experienced surgeon to perform this procedure. Finally, it may not be appropriate in ACL ruptured knees that have co-existing pathologies such as large meniscal tears or osteochondral defects; these patients are generally delayed in return to sport, making the benefit of the fast return with LARS pointless.
Part I of this 2-part Rehabilitation Masterclass has focused on the innovative (and at times controversial) LARS procedure as a means of reconstructing the ruptured ACL. It is still a relatively new procedure that lacks long-term follow-up studies assessing success and failure rates compared to traditional ACL reconstruction. Due to the unique synthetic properties of the LARS, it is proposed that athletes will return to competition much faster than with traditional ACL reconstruction. Therefore, the post-operative rehabilitation will differ significantly in both time and content compared with the traditional ACL reconstruction. Part II of this article therefore discusses in depth the postoperative process following a LARS reconstruction.
in Diagnose & Treat, Hip injuries
‘Coxa saltans’ or snapping hip is a surprisingly common condition in sportsmen and women. Trevor Langford explores the causes and outlines appropriate assessment and management techniques Snapping hip, also referred to as coxa saltans, is diagnosed in at least 10% of the population, with dancers, runners, footballers and weightlifters beingcommonly affected(1). Snapping hip can be identified... MORE
in Diagnose & Treat, Musculoskeletal injuries, Shoulder injuries, Uncommon injuries
Chris Mallac provides an insight into a particular and rare type of posterior labrum lesion known as the ‘Kim lesion’. Glenoid labrum injuries are common shoulder injuries in athletes and research shows that among these, posterior labral lesions form a significant proportion(1). The posterior labrum is particulary vulnerable in sports such as contact football players (NFL,... MORE
in Diagnose & Treat, Hip injuries, Leg injuries, Musculoskeletal injuries, Prevent
In the first part of his two-piece review on psoas major (PM), Chris Mallac discussed the relevant and complex anatomy and biomechanics of this unique and misunderstood muscle. In part two, Chris looks at how PM dysfunction may manifest as a musculoskeletal problem, and the corrective interventions a therapist can use to manage PM dysfunction. PM... MORE
In the first of a 2-part article, Pat Gilham explores the biomechanics of the golf swing and the implications for prevention. The golf swing is a multi-segmented and complex skill, which involves accurate body perception and well-coordinated muscular actions(1). It involves a kinetic chain initiated from movement of the legs and hips followed by the trunk... MORE
in Anatomy, Hip injuries
In part I of this series, Chris Mallac looks at the detailed anatomy and function of psoas major, and the role it plays in lumbo-pelvic stability. The anatomy and function of the psoas major (PM) has received considerable attention in the literature over the last decade. More recently however, the traditional model and understanding of the... MORE
in Email Newsletters, Improve, Knee injuries, Tools and technology
As Karen Litzy explains in her recent article, pain is a complex phenomenon. For a time, it was considered the fourth vital sign. However, it’s an unreliable symptom. Unlike blood pressure or pulse, pain is subjective. It’s expression and perception differs among genders, cultures, socioeconomic status, race, current emotions, and just about every other aspect... MORE
Knee pain is the most common of all sports injuries and virtually every sport has its share of knee injuries and related problems. If you or your client has played sport for any sustained period of time, the chances are you've already experienced at least one bout of knee pain. Be it a temporary, mild nuisance you've shrugged off, or a debilitating injury that forced you to seek specialist help. The good news for athletes, coaches and sports injury professionals, is that thanks to some important recent work in this area, sports scientists now know more than ever about the diagnosis, treatment and prevention of knee injuries. And now you too can share in these insights, courtesy of this special report. MORE
Understand and manage the shoulder's function, recognise how and why pathologies develop and learn the concepts behind current and best practice of shoulder injury management. MORE
Drawing from the knowledge and experience of our panel of sports scientists, physiotherapists and sports therapists we have compiled a holistic, technical and hands-on approach to understanding, treating and managing running injuries. The report covers prevention, physiology, core stability and technique, and includes case studies and illustrations throughout. It will stay with you as an invaluable reference point through your running career, and not only help you stay injury free but also increase your biomechanical efficiency for long term gains. MORE
