This is a very rigid graft and potentially could lead to a limited ability to fully straighten the knee. Hamstring grafts are another option. Typically, two of the hamstring tendons are obtained by using a small incision just below the knee. Two long lengths of tendon are obtained that allow the graft to be doubled over and so achieve a quadruple graft. Since it has four tendon strands, the graft is very strong, up to two or three times the native ACL. Hamstring grafts have been associated with better extension, lower incidence of post-surgical arthritis and better extension strength.
One study on high-performance athletes showed that 98 out of were able to return to the same level of activity after surgery as that prior to the injury. The weakest point, however, is the fixation of the graft to the knee. Unlike the patellar tendon, there are no bone plugs and so the soft tissue part of the graft must heal in the bone tunnels.
This means that fixation initially may be less solid, and it may take longer for the graft to heal within the tunnels. Nowadays there are better techniques to fix the graft on both sides of the knee. In the past, bulky hardware was used, and patients often complained about it. This is no longer the case with newer implants.
The graft tends to be somewhat less stiff than patellar tendon, but this does not seem to lead to worse results. Some studies have shown some residual weakness in the hamstrings after using this type of graft. The majority of papers show no difference in looseness of the knee after surgery, functional results or knee scores, but there are variations in outcomes.
I have used all three grafts in my practice. My favored graft is the quadruple hamstring graft at this point due to newer fixation techniques that achieve solid, stable fixation allowing rapid rehabilitation postoperatively. I do not run into issues with prominent painful hardware after surgery these days with the new implants available.
In my experience, patients tend to have less pain initially after surgery making physical therapy somewhat easier than with patellar tendon.
Although patients with allograft tendon to have an easier time initially after surgery, I would not use this type of graft in the young person due to the higher failure rate. Patients with hamstring grafts are able to have a reliably stable knee with proper function that enables his or her return to sports and an active lifestyle.
View Larger Image. The remaining collagen acts as a scaffold for the host to re-populate and re-incorporate. By around 3 months, patients often feel that the knee is very settled, and moving well. It is understandably tempting to return to sporting activity.
However, this period is the beginning of the time when the graft is below the strength of the native ACL, and is associated with the risk of re-injury.
Working with an experienced physiotherapist is essential. The goals of physiotherapy following ACL reconstruction are initially to regain movement and reduce swelling and pain. Once this is achieved, the next phase is to rebuild strength and focus on muscle control.
Straight-line exercise is used to build fitness. After around 4 months, more strenuous exercise is introduced, depending on the individual progress of the patient. Sports-specific drills may also be introduced. I usually allow training with your team at around months, but no contact sport.
Patients may require one crutch post-operatively, just for a few days, until the pain from the procedure begins to settle. However, knee braces are not required and the graft strength and fixation should be firm immediately post-operatively.
Rehab regimes may vary considerably depending on whether other concomitant procedures are carried out at the same time as the ACL reconstruction. However, the basic standard ACL rehab regime involves:. When tendon tissue is first harvested for a graft, as soon as the tissue is harvested it loses its blood supply. The cells within the tissue, responsible for constantly repairing the fibres of the tissue, thus die and the graft becomes little more than a biological scaffold, in which the fibres will begin to degrade and gradually rupture with time, thereby weakening the tissue.
When the graft tissue is inserted into the knee, it begins to grow a new blood supply. New cells migrate into the tissue and begin to repair and remodel the graft.
Therefore, an ACL graft is nice and strong when it is first surgically implanted.
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