The overall aim of an anterior cruciate ligament (ACL) reconstruction is to restore stability to the knee preventing the forwards movement of the shin bone on the thigh bone and to provide rotational stability. In an ideal world the chosen graft should recreate the anatomical, structural and functional properties of the original ACL.
- Autograft: Harvested from another tendon within your own body
- Allograft: Harvested from a cadaver tendon
Unfortunately, none of these graft types have been able to recreate the exact anatomy and function of the original ACL. By far the Autograft is the most common and comes with fewer complications therefore I am just going to run through this.
Autografts are normally harvested from the hamstring tendon (back of your thigh) or your patella tendon (just below your knee cap). The choice of which tendon to use this is guided by your anatomy and if you have had any previous injuries or surgery.
Patella tendon graft:
This graft is taken from the strip of tendon that runs from your knee cap down to your shin bone. The central one third of the patella tendon is removed with a piece of bone from both the knee cap and the shin bone. This therefore has a small block of bone at each end which is inserted into tunnels on both the shin and thigh bone.
- Early bone to bone healing (approximately six weeks). This is thought to be stronger and resistant to more aggressive rehabilitation following surgery.
- Decreased anterior knee laxity.
- The chance of anterior knee pain is higher therefore less appropriate for anyone who has a profession which involves kneeling.
- Potential knee extension loss.
- Increased risk of post-operative complications: late patella fracture or patella tendon rupture, patella tendinitis.
- Larger incision.
Hamstring tendon graft:
Recently, ACL reconstruction using the hamstring tendon has become more popular. The tendon is harvested from gracillis and semitendinosis then doubled up to make four strands. This is a bone to tendon graft where the tendons are fixated within a bony tunnel. For this type of ACL reconstruction to be successful the tendon graft needs solid healing within the bone tunnel as quickly as possible after surgery.
- 4 bundle graft creating a larger graft diameter.
- Much lower risk of anterior knee pain.
- Smaller incision.
- Pain in the immediate post-operative period is less.
- Longer recovery time. A bone to tendon graft can take ten-twelve weeks to heal to the bone.
- Potential loss of flexibility in bending knee.
- May struggle to regain full hamstring strength from donor side.
While the hamstring graft has become more common there still does not appear to be a gold standard. Both graft choices have many advantages and disadvantages. Making a decision of which graft choice is right for you is difficult but it needs to be specific you and your functional goals.
If you have any questions or you would like to start rehabilitation pre or post-surgery, come and see the team at Bend + Mend Physiotherapy.
1/. Mohtadi, N. G., Chan, D. S., Dainty, K. N., & Whelan, D. B. (2011). Patellar tendon versus hamstring tendon autograft for anterior cruciate ligament rupture in adults. Cochrane Database of Systematic Reviews. doi:10.1002/14651858.cd005960.pub2
2/. Shaerf, D., Pastides, P., sarraf, K. and Willis-Owen, C. (2014). Anterior cruciate ligament reconstruction best practice: A review of graft choice. World Journal of Orthopedics, 5(1), pp.23-29.
3/. Petersen, W., Fink, C., Kopf, S. (2017). Return to sports after ACL reconstruction: A paradigm shift from time to function. Knee Surgery, Sports Traumatology, Arthroscopy,25(5), 1353-1355. doi:10.1007/s00167-017-4559-x