Could Innovations in Ligament Preservation Techniques Bring Personalised Medicine to ACL Treatment?
ACL injury is a common injury in sports and amongst those leading an active lifestyle, accounting for 20% of all knee injuries, and leading to surgery for 11,000 people in the UK every year and 100,000 ACL reconstructions in the USA. The standard one-size-fits all approach of ACL repair is extremely invasive surgery, yet the type and extent of injury can vary greatly between individual patients. The ligament may be stretched, or it may be torn, either completely or partially. The injury may not even be diagnosed until months or years down the line, especially if the patient does not experience swelling, or if muscles in the leg compensate for a loss of stability in the knee.
Until now, the choice of treatment is restricted to one of two options, either to do nothing and adopt changes to lifestyle, or to go through invasive surgery, with assessment influenced by the patient’s age and activity level. However, in recent years, there have been several new techniques at various stages of development that aim to revolutionise patient treatment and find a less invasive repair procedure.
At present, the standard procedure to repair a torn ACL is a “reconstruction” where the injured ligament is removed entirely and replaced with a tendon or hamstring autograft that is fed through two holes in the bones with a metal screw holding the graft on each end. This removal of the patient’s original biology and the necessary incision to produce the tissue to replace the ligament means the recovery process is painful and slow, taking a minimum of nine months post-surgery. Moreover, there is evidence that ACL reconstruction surgery does not prevent the occurrence of osteoarthritis in 10-year follow-up cohorts, this can be demonstrated here. This has inspired surgeons, such as the UK Foundation for Knee Preservation, and innovators to think of novel solutions where the biology is retained as much as possible providing hope for patients in the future.
What does this mean for personalised medicine for ACL injury?
The techniques that are being developed are potentially better for different injury types. The Internal Brace Method (IBM), licensed to Arthrex and developed by Prof Gordon Mackay in Glasgow, is possibly better for injuries in which the ACL has come away from the bone, which is often associated with injuries. It is a procedure that reinforces the ACL with a “bungee cord” to stabilise the joint and helps the healing through the release of local stem cells. It still requires drilling through bones, albeit with smaller holes and uses one BioComposite™ SwiveLock® screw at one end of the cord and a metal button at the other. A further procedure is the intraligamentary stabilization technique, developed by Mathys AG Bettlach and Dr Stefan Eggli in Switzerland, which is normally applied to injuries within 3 weeks. Similar to IBM, it uses a cord that reinforces the ligament, but it uses a spring screw to provide dynamic intraligamentary stabilisation through the Ligamys implant system. In principle every newly ruptured ligament is suitable, but the window of opportunity for surgery is extremely short.
In Boston, a new trial is underway to test the use of a bioactive bridging scaffold to stimulate the anterior cruciate ligament (ACL) to repair itself, which is possibly the least invasive technique and targeting patients with complete tears within 30 days of injury in its second trial. This bridge-enhanced™ ACL repair (BEAR™) method preserves the remaining ACL tissue and uses a protein sponge injected with the patient’s blood as the bridge through which torn ACL tissue will grow and reconnect.
One of the key themes amongst all the new treatments is the requirement to make surgical decisions as quickly as possible after the injury, as the ACL can likely only be preserved if it is operated on within a short space of time (e.g. within 3 months depending on surgical opinion, but not always as Prof Mackay has done operations later when the tissue quality is retained), as the ligament becomes scarred and retracted through time. An MRI scan will assist in the choice of technique. This has an important implication on current patient pathways, which may take longer to diagnose the injury. The £800-£1000 cost of MRI may need to come down to make it more palatable to cash-strapped health systems.
Whereas pharmaceuticals receive financial investment, med tech and trials in surgery have received less interest. In an age where people are living longer and exercising more, not to mention the rise of the MAMIL, these injuries are likely to increase. Going forward, patient pathways need to consider the evidence available for new, less invasive and more personalised treatments, supported by an education and awareness program for doctors and patients. The alternative is that patients are left either opting for screws and grafts or a change in their activities supported by physiotherapy, if the critical window is missed.
To find out more about this topic, please contact Daniel Mekic.