Knee and Shoulder Surgeon
Professor of Mashhad University of Medical Sciences
حرم مطهر امام رضا حرم مطهر امام رضا

Anterior Cruciate Ligament

Anterior Cruciate Ligament

Treatment and Rehabilitation

Anterior cruciate ligament reconstruction (ACL reconstruction) is carried out after an injury to the anterior cruciate ligament. The ACL is essential for normal knee function and stability: it attaches from the bottom of the thigh bone (lateral femoral condyle of the femur) to the top of the shin bone (medial tibial plateau) and prevents excessive forward (anterior) movement of the shin bone, excessive inward (internal) rotation of the shin bone, excessive bending the knee sideways toward the body, and knee hyperextension.

During ACL reconstruction a graft or replacement ligament is used to restore its function. The torn ligament is removed from the knee and the graft is inserted. The surgery is performed arthroscopically.

If you are undergoing surgery the procedure and the rehabilitation will be explained to you by your surgeon and your physiotherapist so that you understand what to expect, and what is expected of you, before your surgery and during your recovery.

Types of ACL Reconstruction Surgery

To repair an injury to the anterior cruciate ligament many different graft types have been used:

Xenografts (grafts from an animal) are rarely used as there are many better alternatives available.

Synthetic grafts fail sooner or later. They were commonly in the past as it doesn’t cause damage to a donor site. Research shows that do not integrate and become ingrown by new ligament tissue from the knee, which was the belief that led to their widespread use.

Allografts (grafts from another person) are uncommon as they have a high failure rate, but are sometimes used for revision surgery. Rehabilitation must be slow in order to allow the graft to try and become a living tissue, as it is initially dead. They are expensive, have long waiting lists, and there is a risk of transmitting diseases such as HIV and Jacob-Cruzfeld disease to the recipient.

Patellar tendon grafts (PTGs) were the most commonly graft used but due to perceived problems with rehabilitation the hamstring graft became more popular. One of the problems with patellar tendon was the high rate of “anterior knee pain” which is pain that occurs on the front of the knee usually around the kneecap. This was thought to occur from the harvesting of the patellar tendon and the patella bone block, and hamstring grafts were used to prevent this problem. Research on hamstring grafts now shows an anterior knee pain incidence of 25-30%, which suggests that the cause is not the harvest of the patellar tendon graft. One cause of anterior knee pain is damage to a nerve that runs across the front of the knee. Other causes of anterior knee pain is, in my view, poor/incomplete rehabilitation and not achieving full hyperextension. If hyperextension is not achieved this means that the patella and extensor mechanism will be constantly loaded, possibly leading to pain. All of these problems can occur whether the patellar tendon or a hamstring is harvested.

Patellar Tendon Grafts

There are several reasons why I recommend use of PTGs:

PTGs are not necessarily more painful – The accelerated rehabilitation programme I have developed illustrates that the pain can be controlled. Ideally pain is controlled with pre-emptive (pain relief before the surgery) analgesia and a strong and potent post-operative pain protocol. Early motion helps to reduce the pain by decreasing stiffness and swelling. Controlling swelling with a Cryocuff will also reduce pain.

Graft healing – The patellar tendon has bone blocks at each end of the graft. This allows rapid and almost guaranteed healing of the graft in the bony tunnels. Bone to bone healing is complete within about 6 weeks. Bone to tendon healing as happens in hamstring grafts is a much slower and less certain. Because of this fixation devices are more crucial and rehabilitation is slower in order to take account of the delayed healing. Some current hamstring studies show that the graft can stretch out, with a slow progressive increase in the KT1000 side to side laxity difference over time. This could be due to the graft itself stretching out or weaknesses at the hamstring bone interface such as the fixation device failing and allowing the tendon to slip within the femoral or tibial tunnel. This may occur if rehabilitation is too aggressive, one of the main issues with hamstring grafts has been trying to get a strong enough fixation device to prevent this. This problem does not really exist for patellar tendon as fixation strength is not as important.

Regeneration of the donated graft tissues – By taking a graft from the person there will be donor site damage, since this cannot be completely prevented, we must try to do as little damage as possible and to help it to heal. A patellar tendon graft can, if treated appropriately, be allowed to heal from the donor site. To do this the defect from the donor site must be closed at time of surgery, as well as bone grafting the patella and tibial bone blocks. This allows the defect to heal, and to heal and potentially be re-harvested in the future. Hamstring tendons cannot be repaired once harvested. When the hamstring tendons are cut the remaining tendon retracts into into the proximal thigh and buttock area. The tendon sheath may be intact but the tendon and the muscle belly retract. This has been demonstrated in studies using isokinetic strength testing which show that patients who have had their hamstring tendons harvested are left with a residual permanent weakness of their hamstring muscles, a permanent weakness of knee flexion power.

The hamstrings are secondary stabilisers of the knee – The hamstring tendons are secondary stabilizers of the knee: if the ACL is torn then the hamstring muscles, by contracting appropriately, can prevent anterior translation of the tibia and decrease the ill effect on the knee from the absent or damaged ACL. It is illogical to sacrifice these tendons to reconstruct the ACL as then both the primary and secondary stabilisers are damaged.

Contralateral/Ipsilateral Patellar Tendon Grafts

A patellar tendon graft can be taken from the same knee (ipsilateral) or the other knee (contralateral). The traditional and by far in a way the most common practice is to take the graft from the same knee so that there is only on one knee with a wound/scar, and only one ‘bad knee’.

The other option is to take the graft from the other knee (contralateral). The originator of the contralateral technique was Dr Donald Shelbourne, who saw that contralateral grafts, sometimes used for revision surgery, had easier rehabilitation and faster recovery times.

Contralateral grafts have the benefit that each knee has only one rehabilitation goal to achieve. The ACL reconstructed knee does not have disruption of the extensor mechanism from taking the graft so is not significantly weakened, it only has to achieve is to reduce swelling and get the motion back. The donor knee that has had the graft taken from it has an immediate weakening effect on the extensor mechanism, but there is no violation of the knee joint so no swelling occurs within the knee and there is no loss of motion, it only has to heal and regain strength.

Rehabilitation is achieved much quicker as strength in one leg and motion in the other leg can be achieved simultaneously rather than sequentially. The rehabilitation and return-to-play times following contralateral PTG can be speeded up by anything between 4 to 8 weeks quicker return to each stage of the rehabilitation programme including return to full sport which in motivated individuals can be as quick as 4 months from surgery. Other advantages include:

– Having a scar on the knee will result in permanent numbness around that scar. Attempting to kneel on a scar feels awkward and unusual, but this feeling is reduced when there are scars on both knees.
– You do not have a ‘good leg’, so you are more likely to walk with equal weight on both legs resulting in a more normalized gait pattern and accelerated rehabilitation.
– Having surgery on both knees is not more painful than having it on one knee. A study I conducted showed that people having ACL reconstruction in both knees at the same time use less painkillers than people having one ACL reconstruction.

Using a contralateral graft requires a separate rehabilitation program for the donor leg. My donor knee rehabilitation programme has two main stages. For first month the patellar tendon defect heals while the patient does low resistance, high repetition exercises, using a series of Therabands and then step downs. The tendon should grow to almost twice the size of the other leg, indicating that it has healed. The second month the donor knee regains strength using high resistance, low repetition exercises.

PTG ACL Reconstruction Surgery

The condition of the knee before surgery is important to the recovery. Before surgery the patient must have must have full symmetrical knee movement (including full symmetrical hyper-extension and being able to sit on their heels easily), little or no swelling, normal walking and good strength. Before surgery our patients are asked to complete a questionnaire and one of our specialist knee physiotherapist arranges an ‘ACL talk’ to explain all about the pre-op, the operation itself and the post-op rehabilitation, if required. The physiotherapist also carries out stability and strength testing assessments, including a KT1000 stability testing to compare the stability of the two knees and isokinetic testing of your leg muscle strength.

ACL reconstruction is a technical operation. The graft must be placed in exactly the right position to function normally following which the knee has to be rehabilitated appropriately. If the operation is done incorrectly the knee won’t return to normal function.

The operation can be done through a mini open incision or via arthroscopic route. It does not really matter which technique is used as long as the technique allows the tunnels to be drilled in the right place and the graft placed in the correct position. I use a minimal medial open technique. I feel it is the best and most reproducible method to facilitate independently drilling the tunnels in the correct place every time. If all the portal sizes of the arthroscopic techniques are added up in length the total incision size is not significantly different from a minimal open approach. There is no difference in rehabilitation outcomes between an open and arthroscopic approach.


Rehabilitation after anterior cruciate ligament reconstruction surgery is critical to a successful outcome……Below is an outline of the standard advice I give to patients.

This is also available in a more complete form in my patient information booklet. Also available is an example of an exercise regime for recovering after a contralateral PTG reconstruction.

The day of surgery

Following surgery, an elastic stocking (TED), light dressings and a CryoCuff are placed on your knees. A CryoCuff provides compression to prevent swelling and keeps the knee cold to minimise pain and swelling. The cuff should fit snugly on the knee at all times, except when exercising, and the water should be exchanged every 30-40 minutes to keep it cold. You will be shown how to use the cryocuff and will take it home, but it will require a supply of ice.

A physiotherapist will see you before surgery to provide an exercise log sheet and instruct you in your exercises. These are to be completed every 2 hours. The exercises included are:

Heel Slide Exercises – Lying down, slide your heel towards your bottom, use a towel or your hands to assist the knee bend as far as possible. Hold this position for a minute then pull further for a few seconds before you release it. Repeat this 10 times.

Towel Pulls – Keeping your thigh flat on the bed, use a towel around your foot to pull and lift the heel off the bed. Use one hand to hold the towel and one hand to push down on your thigh to stop it coming off the bed. Then try and tighten your thigh muscle to hold this position when you release the towel. Hold for 10 seconds and repeat this 10 times.

Extension Stretches – Place your heel on the CryoCuff container and relax your knee into a straight position. Place ankle weights over the front of your shin, or oven gloves with cans in each side over the front of your leg to increase the stretch. Prop your other leg on and compare the extension. Hold this position for 10 minutes.

Knee Drops – With heel on the cannister bend your knee slightly and then relax and let your knee drop down straight. Repeat this 10 times.

Straight Leg Raise – From resting on the CryoCuff container, tighten your thigh muscle and lift your leg up, keeping your knee straight and hold for 10 seconds. Repeat this 10 times.

The day after surgery

The TED stocking will remain on to help keep dressings in place and provide light compression. You should remain in bed with you leg in the CPM and CryoCuff, except for going to the bathroom and completing the exercises every 2 hours. The Physiotherapist will visit to help you get up and start walking correctly so you can go to and from the bathroom, and provide you with crutches to aid. When you walk you should put as much weight on your leg as is comfortable. Putting weight on your leg will not affect the reconstruction; however, being on your feet with your knee below the level of your heart will cause your knee to swell. This swelling will reduce the movement at your knee and so slow your recovery and delay your rehabilitation.

For the first week after your surgery you should elevate your leg with the CryoCuff on at all times except when exercising or going to the bathroom. When elevating your leg at home, put some pillows under your calf and foot, not under your knee.

You will be discharged from hospital the day after the operation, providing you achieve the following:

– Full Hyperextension of your ACL knee
– Good flexion of your ACL knee (around 70 degrees)
– The ability to lift your ACL leg with your own muscles, and hold it up
– Walking independently with crutches
– Understand your exercises and instructions for home
– Satisfactory pain control

The first week at home

An Intravenous anti-inflammatory, will be set up on the day of surgery to run for 24 hours. This aims to control your swelling and pain. On day of discharge you will be given an additional boost of intravenous anti-inflammatory to last through the day.

Prof Jari will prescribe you painkillers on discharge, and these will include an oral anti-inflammatory and another basic painkiller, like paracetamol. These two medications must be taken regularly for the first 14 days whether or not you have pain. Other painkillers may be used on the ward, or prescribed for you to take at home, depending on your pain levels. Please record any extra medication you take on the sheet provided. You should have an appointment to see your physiotherapist approximately one week after your surgery. If this is not the case you must ring to arrange this.

During the first week you should:

Elevate the leg and minimise walking – While at home you must lie down with your operated leg elevated and only walk to the toilet and back to bed. Standing and walking will cause swelling to gather quickly, which can delay your recovery.

Use your cryocuff regularly through the day – Use this all the time your leg is elevated. Refill the canister with ice regularly.

Work on the knee straightening exercises (heel-prop) – Ten minutes of every hour should be spent doing the heel-prop exercise where the heel is placed on a rolled up towel or the cryocuff cannister and allowed to stretch the knee straight.

Continue the heel slide exercises – This exercise will be helping you to increase your knee bend again. Work slowly and gradually to increase your bend.

Work on thigh muscle strengthening exercises – Keep working on the thigh tightening exercise to start the thigh muscles working again and to build them up.

Numbness around your cut is normal. The numb area will shrink but a very small area of numbness may remain permanently. Occasionally problems do occur, signs of possible problems include:

– A slight fever is normal but a very high temperature or long lasting fever should be reported
– Increased knee soreness not reduced with medication
– Stomach upset after taking medication
– Increase drainage from the the wounds or dressing problems
– Sustained loss of knee movement
– Marked calf pain or swelling

If you experience any of these problems in your first week please contact Prof Jari, your GP or your physiotherapist.

Physiotherapy Appointments


After the physiotherapist has seen you for the first time after the surgery they will decide how often they would like to see you depending upon your progress. At the beginning you may need more support and advice, and less as you become more active and confident with your exercises. It is very important that you continue to work on your exercise programme regularly. If things change or you are worried about your progress please ring Prof Jari or your physiotherapist for advice.

The rehabilitation programme is designed so that you can do it yourself at home. We will simply guide you on what to do and what not to do, as well as monitoring your progress. If you want the best result it is up to you to work hard on your rehabilitation. We will ask you to complete questionnaires at 1 month, 6 months, 1 year and 2 years after your surgery.

You will be seen two weeks after surgery by your physiotherapist who will check:

Range of knee movement – Hyperextension should be full and easy and your bend should be almost full
Swelling – This should be less than the previous week
Leg/thigh muscle control – You should be able to tighten the thigh muscle and lift your leg off the bed whilst keeping it straight.
Walking – You should be walking normally now without crutches

Your physiotherapist will design an individual rehabilitation programme for you depending on your goals and needs. At each visit your strength, range of movement and swelling will be checked. Your rehabilitation will advance as your strength, comfort and confidence will allow. Your physiotherapist will continue to monitor your rehabilitation until you have returned to your pre-injury, fully competitive level of activity. Additional clinic or physiotherapy appointments will be made if there are thought necessary by your physiotherapist and Prof Jari.

Your physiotherapist will also carry out stability and strength testing to monitor your progress, this will include:

KT1000 stability testing to compare the stability of your knee with the opposite knee
Isokinetic testing to test your leg muscle strength. We compare your operated leg with your other leg (approx 3 months).


  • Dr. Mohammad Hosein Ebrahimzadeh
  • Knee and Shoulder Surgeon
  • Professor of Mashhad University of Medical Sciences
  • Office Address :Floor 3, Nikan Building,
  • Koohsangi 6, Koohsangi Street, Mashhad, Iran.
  • 38541812-051
  • E-mail :
Dr. Mohammad Hosein Ebrahimzadeh انجمن جراحان ارتوپدی