The Anterior Cruciate Ligament is the main support to the stability of the knee in a forwards direction, that is it stops the femur (thigh bone) from sliding off the tibia (shin). If ruptured, the knee often becomes unstable and results (apart from pain and swelling) in difficulty moving or twisting without “giving way”.
In an older population it may not be necessary to repair if the episodes of instability are few enough and seldom enough, and if they are able to become mostly pain free. In a younger population, it is often recommended to undergo reconstructive surgery.
***Update*** A growing body of evidence suggests that up to 50% of people suffering ACL rupture who manage conservatively (no surgery) are able to return to normal sporting activity with minimal to no pain or instability. Research on rehabilitation protocols, and return to sport criteria are beginning to suggest that reconstruction may not always be the best option.
The main types of ACL reco (ACLR) are:
- Patella graft: middle third of patella ligament is cut out, along with a small cube of bone from patella and tibia. Strong graft, good outcomes but often complicated by Patellofemoral dysfunction (Knee cap tracking)
- Hamstring Graft: Part of the lower, inner hamstring tendon is harvested, sewn into a bundle of four and then pulled through some tunnels drilled into the femur/tibia. Great outcomes, minimal post op complications other than occasional tear of the harvested hamstring, though this rarely effects outcome or slows rehabilitation. This is the most common ACLR done in Australia currently
- LARS: Ligament Augmentation and Reconstruction System. This is an artificial graft, and since it doesn’t have to be harvested from the body, there are fewer post operative barriers to rehabilitation, leading to shorter recovery time, and faster safe return to sport (sometimes as short as 8-10wks).
- Quadriceps Graft: a section of the quads tendon ABOVE the patella is harvested for the graft. This thick, strong tendon makes for a sturdy graft, and early evidence shows fewer complications post operatively than the patella graft, or hamstring graft.
Unless time is the major factor (professional athletes) most surgeons still opt for the hamstring as the graft of choice, unless prior trauma or previous reco has rendered the graft site compromised, however the literature supports the third-generation LARS as having similar or slightly lower failure rates compared with hamstring or patella (depending on the study) at the four year mark post-op.