ACL graft options

There are pros and cons with each of these different graft types, as summarized below:-


Hamstring autografts

What is it?

  • Two tendons (the semitendinosus and the gracilis) are cut from the inner (medial) side of the patient’s own knee and removed. These are put together and folded over to give 4 strands of tendon, which normally gives a good strong graft.

Pros

  • Readily available from the patient’s own knee (the same knee or from the knee on the other side).
  • Most of the time is a good strong graft.

Cons

  • Causes further damage to the knee by ‘robbing Peter to pay Paul’, with hamstring pain and 10% hamstring weakness.
  • 5% of the time the graft is not good enough, which means that an alternative has to be used.
  • 40% of people get numbness at the front of the shin.

Mr McDermott’s take on it

  • This is probably now the most favourite graft type in the UK today.
  • There is no additional cost because you’re taking tissue from the patient’s own knee. However, the graft is not 100% reliable and there are some negatives with harvesting the tendons.


Patellar tendon autograft

What is it?

  • The middle third (1cm width) of the patella tendon is cut from the front of the knee, along with a small block of bone from the tendon’s attachment to the patella and a small bone block from the tibia.

Pros

  • This gives a reliably good graft.

Cons

  • It requires a larger incision at the front of the knee, and there can be increased long-term pain at the front of the knee, scarring or inflammation in the remaining portion of the patellar tendon, and difficulty with kneeling on the front of the knee.

McDermott’s take on it

  • Although this is a good graft, it is actually my least favourite graft because of the damage/irritation that harvesting the tendon can cause. It is, however, an ideal graft to go for as a 2nd choice, should a harvested hamstring graft turn out to be too thin, too short or suboptimal in any way (1 in 20 times)

Synthetic grafts

What is it?

  • Various different types of synthetic graft have been trialed in knees in the past, including carbon fibre, Dacron or PTFE.

Pros

  • Quick and easy.

Cons

  • Expensive. Inferior results compared to ‘biological’ grafts. Can degrade or ‘fall apart’ and many disasters reported.

Mr McDermott’s take on it

  • Personally, I wouldn’t touch a synthetic graft with a barge pole!

Allografts

What is it?

  • Tendon is taken from a donor and provided by a registered Tissue Bank

Pros

  • Tissue is very carefully tested and sterilized, and the estimated risk of graft contamination = <1 in 1.6million.
  • No living cells, so no need for tissue typing (matching donor and patient) or immunosuppressive drugs.
  • Readily available, and reliably good quality (quality assured by the Tissue Bank in advance).
  • Quicker operation (shorter anaesthetic), as time not required for graft harvesting.
  • Less damage to other knee structures (not robbing Peter to pay Paul) and therefore less post-op pain.
  • Less pain and no damage to the hamstrings, and therefore faster early post-op rehab.
  • Much lower risk of potential complications (such as patellar problems and anterior knee pain from the harvesting of patellar tendon grafts, or shin numbness and nerve damage plus hamstring weakness from the harvesting of hamstring tendons).
  • The allograft tendons tend to be stronger than a standard average hamstring or patellar tendon autograft.
  • Equally good long term outcomes as autograft hamstring or patellar tendon grafts.

Cons

  • If the use of an allograft is not covered by the small print of your insurance policy or if you are self-funding your surgery, then the hospital will charge you directly for the cost of the allograft, which is about £3000 or so.
  • Some people might tell you that there is increased potential stretching out of the graft and a slightly increased risk of re-rupture with the use of an allograft. If you do hear this, then you should be aware that the person telling you this is actually rather poorly informed! …  There are some studies in the literature that have shown slightly poorer outcomes with allograft tendons vs autograft tissue, and these studies come from the U.S. However, in the past the allograft tendons used to be sterilized with gamma irradiation. The gamma radiation weakens the chemical bonds in the collagen fibres within the tendon tissue, slightly weakening the tissue. Therefore, quite simply, we now don’t use gamma irradation for sterilization, and instead we use grafts that have been screened, tested, chemically sterilized and then deep frozen. If one excludes the irradiates grafts and looks just at the chemically sterilized grafts, then studies have proved that there is no weakening of the tissue, and no stretching of the graft or increased re-rupture rates.  Furthermore, many of the American studies into the use of tendon allografts for ACL surgery used either patellar tendon allografts or Achilles tendon allografts. Both of these have bone blocks at the ends, and the bone allograft blocks are a potential ‘weak link’ and source of potential weakness. However, in my practice I would never use a bone-tendon composite allograft (patellar tendon or Achilles) and I only ever use either the tibialis anterior tendon, two semitendinosus tendons combined, or a tibialis posterior tendon – all of which are perfect for replacing an ACL.

McDermott’s take on it

  • Personally, if I ever have to have my ACL reconstructed, I’m having it done with a tendon allograft, for sure. Tellingly, when I operated on one of my colleague’s knees, who is also a knee surgeon, and reconstructed his ACL – he opted to have a tendon allograft.