The surgeon must also optimise the chances of success by attending to damage to other structures that participate in stabilising the knee.
When first undertaking the initial reconstruction the surgeon has a number of options:
A primary repair involves suturing or sewing the torn portion of the ACL rather than replacing it with a graft. Multiple studies have shown poor results with this technique and, in my opinion, there exists no indications where this procedure would be offered. In my practice, a bone-patellar tendon-bone autograft carries a 95% success rate in restoring stability to the knee joint and less than a 1% complication rate. Many other surgeons around the world have reported similar results with this autograft and that is why primary repair is no longer offered at most major centers.
Extra-articular iliotibial band procedure
The iliotibial band is a strap of fibrous tissue on the outer side of the thigh. This material is sometimes stripped off and used as a graft material to try to stabilise the knee from outside the joint. Many studies have also reported poor results following this procedure, except when done in young children. However, in my practice, the ITB procedure is used in some cases to augment intra-articular grafts in revision knees. The decision of whether to incorporate the extra-articular procedure is based on results of the pivot-shift test and how much instability the patient suffers from - those who have giving-way with routine daily activities and a fully positive, grade 3 pivot-shift test, may benefit from the combined procedure.
Most ACL procedures nowadays are intra-articular reconstructions where graft material is used to replace the original cruciate ligament within the joint cavity. Intra-articular reconstructions options are:
An autograft is where the graft material is harvested from the patient. This may also be referred to an an 'autologous' graft. Where the tissue is taken ('harvested') from the knee with the cruciate damage, it is called an 'ipsilateral' harvest. Where the tissue is harvested from the opposite knee, it is called a 'contralateral' harvest. The autograft choices are:
- bone-patellar tendon-bone autograft
- semitendinosus-gracilis hamstrings
- quadriceps tendon-patellar bone autograft
An allograft is harvested from a human donor (transplant), and then treated and stored usually via a 'tissue bank'. The material, besides the tendons mentioned above, may also include Achilles tendon (from the back of the ankle).
Two of the types of grafts have the benefit of being attached to bone blocks - the bone-patellar tendon-bone graft has a bone block on each end, and the quadriceps tendon-bone graft has a bone block on one end (and soft tissue on the other). The benefit of the bone on the graft ends is that, once the graft is correctly positioned, the bone blocks are able to unite with the bone in the walls of the tunnels through which the graft has been threaded.
Where there is no bone block - for example on the upper end of the bone-quadriceps tendon graft, or on both ends of a hamstrings graft, fixation devices play a greater long-term role in holding the graft in position, eg -
1 Noyes FR, Butler DL, Grood ES, Zernicke RF and MS Hefzy. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg Am. 1984;66:344-352.
2 Noyes FR, Barber-Westin SD. Revision anterior cruciate surgery with the use of bone-patellar tendon-bone autogenous grafts. J Bone Joint Surg Am. 2001;83:1131-43.