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Anterior Cruciate Ligament (ACL) Reconstruction

Arthroscopic Anterior Cruciate ligament reconstruction has become a much more refined procedure over the past ten years. Our operating times (30-50 minutes), hospital stay (12 hours) and recovery time (running in 4-6 weeks, sports by 3-4 months) have all improved with increasing experience.

We have come a long way since doing the first of these arthroscopic procedures in Auckland at the Adventist Hospital in the early 1990s, which were often difficult, stressful and taking over two hours.

Several of us now have personal series of over 2000 cases. The results of our reconstructions are much more reliable - patients may expect a normal knee with a 95% probability. We are now much more confident and aggressive in our rehabilitation - patients are encouraged to work on regaining full knee movement and muscle strength from the outset.

Our current approach is to take the patient through a "prehabilitation programme" - which involves maximising muscle strength about the knee and restoring full movement - through surgical ACL reconstruction - and straight back into the same exercise programme within days of operating. The goal of early rehabilitation is to return to light running within 4-6 weeks.


  • When is it safe to return to sport?

The best answer at this stage is when the knee "feels" normal. This means full muscle strength in the quadriceps and hamstring muscle groups, a full range of knee movement, and at least 6 weeks of running.

I advise that unless a full-speed sprint distance of 50-70 metres can be run, without any pain or sense of instability or weakness in the knee, that a return to sports training should be deferred.

  • Should sport be avoided while the graft is theoretically weak?

Probably, but Kiwis just won't wear this. They will go back to sport when their knee feels normal, and telling them not to is usually an unproductive exercise. In the group of patients returning to sport at 3-4 months with a fully rehabilitated knee, we have not witnessed a rash of early graft re-ruptures.

  • Is bracing necessary after operation?

Usually no. The important thing is to restore movement, muscle strength, coordination and proprioceptive function. These are the 'protective' factors, not reliance on a brace.

  • What can be done if the graft fails?

A revision (re-do) procedure can be undertaken utilising either a graft from the opposite knee, or a hamstring or patellar tendon graft from the same side (depending on what was originally used). However, the failure rates of revision procedures rise to 10-15%.

  • Can an ACL reconstruction result in knee arthritis (OA) ?

Only if the graft is of excessive size or at too much tension, 'constraining' the knee. However, these factors have not been clearly linked to development of OA. However, a chronically unstable knee will tend to tear up cartilages, damage joint surface and subchondral bone, and these are the arthritis-producing factors. An ACL reconstruction is probably protective

  • Can the PCL be reconstructed arthroscopically?

We now have well-designed posterior cruciate ligament reconstructive procedures which are done arthroscopically. However, our collective experience is limited, due to the fact that thereconstruction rate for PCL is only 1% or so of the numbers of ACL reconstructions done. Functionally, patients with untreated PCL ruptures seem to fare much better then those with ACL ruptures.

Rehabilitation from arthroscopic PCL reconstruction is slower, return to sports should be delayed for 6- 12 months, and the success rates of arthroscopic PCL reconstruction are only of the order of 60-80%. This figure represents lack of surgical experience, difficulty in achieving correct placement of the graft, and the need to supply a much stronger ligament graft than required for an ACL reconstruction.

  • What graft options are available?

Central third patellar tendon, multiple strand hamstring tendon, quadriceps tendon or allograft tendon may be used. Each has its advantages and disadvantages, but the hamstring and patellar tendon options are most commonly used. Artificial ligaments are no longer used. Xenograft (animal) tissue is not used in this country.

The major step forward in recent times, however, has been use of patellar tendon allograft.

Using human donor (allograft) patellar tendon grafts to reconstruct a deficient anterior cruciate ligament is a major advance. Up to this point, there have been issues regarding availability, safety (in terms of donor screening), preparation (resulting in questions regarding tensile strength depending on the method used), guarantees of sterility, and cost. All these issues, apart from (in my opinion ) the final consideration, have been addressed such that use of allograft for this application is in my opinion the way of the future.

The advantages of using an allograft centre on the fact that the graft does not need to be harvested from the patient - either from a middle third patellar tendon, or from a hamstring. This avoids the problem of donor site morbidity, and hence the recovery from an ACL reconstruction is much accelerated. In effect, the patient has only had a knee arthroscopy undertaken - drilling bone tunnels and placing a graft across the knee adds little to post operative symptoms in comparison to an arthroscopy. The accelerated recovery time is reflected in reduction in time taken to return to work (particularly in patients with physical jobs) and as a rule of thumb, the overall recovery time (in comparison to that taken following a patellar tendon or hamstring graft) is roughly halved.

The downside risks are of the (theoretical) risk of transposing "slow virus" into the body, but this has not ever, to my knowledge, been documented in this application. Hence, it is theoretical risk only. There has been evolution of the donor screening and graft preparation process (based in the USA) such that these issues, in my view, are no longer a consideration. The cost issue remains.

At present, ACC are funding primary allograft reconstructions, but in view of the cost implication, the question remains as to how long this funding will continue.

ACC have been made aware of the advantages of having ACL reconstructions done with allograft - in particular, this has implications regarding their exposure to Earnings Related Compensation with longer return to work times when autografts are used. A cost-benefit may be demonstrable. Should this technology application become the standard, it would be in the interests of insurers to work with ACC and the supply companies to reduce unit costs of patellar tendon allografts by bulk purchases. At present, this is not under consideration with ACC.

The further option, should ACC withdraw funding, may be able to obtain this additional funding for an allograft through private insurance.

This evolution of ACL reconstruction using allograft is, in my opinion, a major step forward. I have been undertaking arthroscopic ACL reconstructions in Auckland since 1991, and I can say with confidence this is the most major advance that I have seen in the field over that time, and one that needs to be actively promoted.

  • Does it matter what type of graft is used?

The short answer is no.

What matters is that the graft ends are placed in the correct spots in the knee, that the graft is at the right tension, and is isometric (not tensioning of slackening through the range of movement) and that fixation of the graft is firm.

The graft must be of adequate size, but not impinging against bone within the intercondylar notch of the knee, leading to abrasion of the graft and possible obstruction of knee extension.

  • How strong is the graft?

If the graft is well fixed at operation, it is initially quite strong - even stronger than the native ACL. However, over several weeks the graft softens, becomes re-vascularised, and the collagen scaffold becomes re-populated with cells - the tensile strength in the graft does drop through this phase, however, by how much? is not known precisely. The graft strength then returns to normal over a 12-18 month period.


Following your ACL reconstruction

Dressings / Wounds

Prior to leaving hospital you will have had your knee dressing changed, and a double thickness elastic ('tubi-grip') stocking applied to your knee. The dressing is waterproof and it is quite safe to shower and get into the pool. Remove your elastic stocking before showering. The dressings can be peeled off at 5-6 days. Cover the wounds with band-aids. The small stitch ends will be trimmed at your post operative visit with me at 7 days.

Pain Medication

You should be discharged with a supply of paracetamol, voltaren and tramal tablets. Take the panadol and voltaren regularly for the first 3-4 days. Should you get any symptoms of stomach upset, stop taking voltaren. You should take two paracetamol tablets 4-6 hourly, regularly, following discharge. If you are still in a lot of pain, especially at night, take the tramal. After 3-4 days take painrelieving medication only as necessary. Use ice packs around the knee over the first day or two when you have your leg up-which should be most of the time when you are not doing your exercises!


Crutches are to be used while you are still limping - try and discard them and walk as normally as possible, as early as possible.Remember; heel in first, push off from the toes. There is no need to protect your knee. The ligament graft inside the knee is very firmly fixed. Your job is to get it moving.

Activity / Physiotherapy / Pool

Plan on resting up at home for the first day following discharge, although following your hospital physiotherapists' instructions on exercises. You should be in the pool on the second day, and starting to use an exercycle. You should return to see your own physiotherapist within 2-3 days of discharge, and get your post operative rehabilitation programme underway. It is not necessary to push this programme too hard over the first 7-10 days, but by two weeks, you really need to be putting in a concerted effort.

It is helpful to get into a swimming pool within the first two days at home - being in water seems to make it easier getting the knee movement going. Water-walking is good exercise at this stage, and helps in restoring normal walking patterns. If your waterproof dressing looks wet underneath, peel it off and put band-aids on the wounds.

Knee movement

It is important to maintain your range of knee extension (full straightening) over the first week or two. A common problem is a loss of this extension range in the first few weeks. Work on getting the knee out straight with the heel rested on a support, and the back of the knee lying free. Also, when standing, get into the habit of standing on the operated leg, with the knee locked back. When walking, make sure the knee is locked out straight at the heel-strike phase of walking. Try and avoid limping - walk as normally as you can. If you need to limp, you need to use crutches.

Follow-up visits / Problems

Your follow up visit with me should be made at 7-10 days. Up to that time, if there are any concerns about your knee, please contact me at my office, or home. To contact me, click here. If there is an urgent problem, and I can not be contacted for any reason, could I suggest that you make contact with your nearest White Cross Accident and Medical Clinic. However, please try and contact me directly as well.