The ACL is one of the most commonly injured ligaments of the knee. For those facing a knee reconstruction, learning about the surgical techniques employed today, and how they differ from historical techniques makes for an interesting read. While the orthopaedic community has learnt a great deal about the humble ACL over the past two centuries, there is always more to learn and techniques continue to evolve.
History of ACL repair
The first reported surgical ‘repair’ of the ACL was conducted by Mayo Robson in 1895. His description was based on a miner from the UK who had injured his knee 3 years prior. Mayo Robson performed a suture repair of both the ACL and PCL and the patient was able to return to work in the mines. ‘Repair’ of the ACL utilises a direct suturing technique of the torn ACL, which is in contrast to the knee reconstruction techniques that now dominate the field.
Interestingly, suture repair of an inured ACL was conducted regularly up until the mid 1980’s. The majority of these techniques utilised an ‘open’ approach with the patient spending up to 6 weeks in plaster following the procedure.
While suture repair went out of favour in the 1980’s due to an increased rate of failure, there has been some emerging work performed in the USA to start offering ‘repair’ of the torn ACL in select cases.
History of ACL Knee Reconstruction
An ACL knee reconstruction involves replacing the injured ACL with a donor graft that will go onto function as an ACL. There are several graft options that can broadly be grouped into Autogenous (Coming from another body part of the same patient), Allograft (Coming from another person), and Synthetic.
In Australia, Autograft is certainly the most commonly used graft type. While Hamstring and Patellar tendon grafts are the most commonly used grafts, other options include a partial thickness quadriceps tendon, and the ITB (which is rarely used nowadays)
The first ACL Knee reconstruction was performed by Ernest Groves in 1917 using an ITB transplant. The patellar tendon graft was first used in 1935 via an open technique.
In the 1970’s ‘non anatomic’ ACL reconstructions came into favour. While there were several variations of these techniques, they tended to be based around providing a lateral restraint to the internal rotation that occurs in an ACL deficient knee. These were typically carried out via an open incision along the outer aspect of the knee and a strip of the ITB was used to ‘tether’ the outer aspect of the knee. Despite some promising results early, attention soon turned towards ‘intra-articular’ knee reconstructions to provide longer term stability.
It wasn’t until the 1980’s that ‘keyhole’, or arthroscopic, knee reconstructions were performed. Clancy is often credited with the first free patellar tendon graft which was reported on in an article published in 1982.
The first description of using the hamstring tendon as a graft for a ACL knee reconstruction was by Riccardo Galleazi in 1934. His technique differed from what we are used to today. He utilised a three incision ‘open’ technique that left the hamstring tendon attached to the tibia. Following the procedure a leg cast and limited weight bearing was prescribed.
Since the mid 1980’s, there has been an emergence in arthroscopic knee reconstructions. Regardless of the surgeon’s preferred graft choice (i.e hamstring tendon), these techniques aim to position the graft in an appropriate position to re-create the function of the native ACL.
Synthetic grafts have long been considered the wholly grail of ACL knee reconstructions. F. Lange from Munich was the first Surgeon to attempt replacement of the ACL with braided silk in 1903. Unfortunately this failed. Over the decades there have been several synthetic grafts that have been used with varying success. Unfortunately most synthetic grafts have had difficulty maintaining long term success rates and have fallen out of favour. While more advanced options still exist currently, their use requires careful selection.
ACL Knee Reconstruction – the last 15 years
In more recent times, surgical units have been exploring various concepts in relation to an ACL knee reconstruction. While results have been acceptable, there is still a quoted re rupture rate of 10-20% over time. This has led researchers to explore the following techniques
Double Bundle ACL Knee Reconstruction
The native ACL is known to consist of two bundles – the anteromedial and the posterolateral bundles. With the hope of reducing the re rupture rates, several surgeons started performing double bundle reconstructions in the early 2000’s. While this has been shown to create a more ‘stable’ knee when assessing certain parameters, there has been some concern regarding the complexity of the procedure, the potential for complications, and a limited functional benefit to patients. While some centres still offer this technique, it has fallen out of favour in recent times.
Partial Bundle ACL Knee Reconstruction
As mentioned previously, the native ACL is made up of two distinct bundles. With a recent progression in our understanding of the anatomy of the ACL, researchers have started performing single bundle reconstructions in the presence of an intact bundle. This allows for the preservation of the non injured bundle of the ACL if there is one still intact following the injury.
Intra articular knee reconstruction Plus a lateral tenodesis
As mentioned previously in the article, many early techniques for ACL reconstruction involved making an incision over the outer aspect of the knee to prevent rotation of the tibia with the use of a soft tissue tether. While this technique has fallen out of favour in isolation, the concept has not gone away completely. In fact, researchers are now assessing whether a certain subset of high risk patients do better with a combination of an arthroscopic reconstruction PLUS a ‘lateral extra-articular tenodesis’. This is an evolving area with the field of ACL knee reconstruction surgery.
As you can see there has been much research going into how to perform an ACL knee reconstruction. This field is continuing to grow and its important that your surgeon keeps up to date with the latest in emerging evidence and surgical techniques.