What are ACL and PCL?
There are two cruciate ligaments in the centre of the knee, the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) named because of their relative tibial (shin bone) attachments. The ACL runs from the back of the femur (thigh bone) to the front of the tibia. The PCL is attached to the back of the tibia and runs forwards to the front of the femur.
Spoiler title
The ACL provides mechanical stability and also gives proprioception (sense of relative positioning of femur and tibia). It is the primary restraint to forward movement of the shinbone and is extremely important in providing rotational stability to the knee. This combination of deficiencies makes the knee give way. This can result in lack of trust in the knee and also result in meniscus and joint surface damage.
Why doesn’t it heal when ruptured?
The ACL has blood vessels and is enveloped in a sheath that also carries blood supply. When it ruptures along with the sheath, the blood dissipates in to the knee with no clot formation and hence is unable to heal.
Should I have a MRI scan?
The diagnosis is usually with the history and examination. MRI scans are not always necessary
Should I have an ACL reconstruction (replace ruptured ligament with graft)?
There are two options for you after an ACL rupture.

1. Modify activities and not have surgery-By adequate training of muscles and balance around the knee and modifying activities, some patients may not have giving way. If the gives way after such a programme, then go for surgery.
2. Surgery- This is performed to treat instability. Should one be keen on twisting activities as is common in sports like football, rugby and racquet sports, then instability is predicted. ACL reconstruction is recommended early to prevent meniscal damage.

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In general ACL reconstruction has a high success rate for most patients unlike that for repair. Steadman has reported success with a technique called ‘healing response’. See the abstract to his article here (http://www.ncbi.nlm.nih.gov/pubmed/16468488). This might work for a very select group of patients
What is the success rate of ACL reconstruction?
Literature suggests that nearly 90% of the patients have successful symptom and functional outcome with ACL reconstruction. Failure can often be due to additional meniscus or articular cartilage damage. The knee would still not be entirely normal after an ACL reconstruction.
What are the risks?
Risks are rare and some of the unsatisfactory results are due to co-existing meniscal and cartilage damage. The literature reported risks are infection (rare), stiffness, numbness around scar, swelling, thrombosis, persistent pain or instability, graft re-rupture and arthritis.
What should I do before surgery?
Regain full movements and reduce pain and swelling
Avoid further twisting injuries
Avoid muscle wasting by doing isometric exercises, static cycling, cross trainer and half squats.
The surgery. What happens on the day?
The operation is usually done as day-case. Your surgeon and the physiotherapists will see you on the morning of the surgery and this gives another opportunity to ask any questions.

The operation is performed usually under General Anaesthesia and takes about an hour. When you are asleep, the anaesthetist might inject a local anaesthetic agent around the nerve in your thigh to numb the leg and your surgeon might also inject painkillers around the knee during the operation.

Your surgeon then carefully examines your knee to further establish ACL deficiency. Most of the surgery is performed via two keyholes, but you would have a 2-4cm scar (see picture) through which your own tendon would be harvested. Any meniscus or articular cartilage surgery is done simultaneously through the keyhole. The ruptured ACL is removed using a shaver and replaced using the tendon harvested. The new graft is fixed with special buttons and/or screws.

What happens after the surgery?
You would be in a recovery ward until your anaesthetic wears away. Don’t be surprised to notice numbness in your thigh and leg as this may be due to nerve block providing pain relief. You would have a bulky bandage. Knee braces may be used if there has been a simultaneous meniscus repair. Some centres may routinely use a knee brace and a Continuous Passive Mobilisation (CPM) machine.
Your surgeon would visit you, show you pictures of your knee and explain about your operation and any changes to your early rehabilitation. You would have a post-operative check x-ray of your knee. The physiotherapists would then advice early rehabilitation to regain knee movements. You are likely to mobilise with the aid of crutches and then go home. An outpatient appointment would be made for physiotherapy within a week. The simplest exercises to do after you get home are quadriceps bracing and heel slides (See rehabilitation page).
What about wound care, can I shower and how can I reduce swelling?
The bulky dressing can be taken down in 24-48 hours and the simple adherent light dressings left behind or replaced. You may notice sticky tapes that have been used to seal your arthroscopy portals. Don’t worry if these tapes come off. Keep the knee dry for 10 days until the wounds heal. If you shower the knee, blot it dry.

You may notice bruising or discoloration at the back of thigh or leg. This can be from bleeding from hamstring harvest. Intermittent icing or use of cryocuff with compression is beneficial. Don’t leave ice on the skin for longer than 15-20 minutes at a time.

Should I keep crutches and what about weight bearing?
Weight bearing does not affect the ACL graft and helps quadriceps recovery. If you have had a femoral nerve block you would feel weak in the thigh muscles and hence use crutches even indoors to mobilise after surgery. Keep the crutches for 2 weeks or longer depending on quadriceps control and swelling. Should you have had a simultaneous microfracture or meniscal repair then you may have to keep weight off for 6 weeks.
When can I start driving?
For the right knee stay off driving for of 4 weeks and for the left knee at least 3 weeks (UK). This also depends on range of motion and ability to do an emergency stop. Make sure that you inform your insurer.

When ACL reconstruction is performed along with microfracture or meniscus repair please follow the specific rehabilitation programme from your surgeon.

When can I return to work, heavy duties and sport?
Each individual patient is different in the recovery period and it is about your knee being right for that activity. In general the following guidelines help: Office work- return approximately 2-3 weeks Heavy physical work- 8-12 weeks Sport- most patients get back to contact sport by 8 months. Skiing-12 months.
You should see your doctor urgently if you:
have pain, swelling or tenderness in the joint which is getting worse,
develop a high temperature,
see fluid, pus or blood coming from the incisions, or
develop numbness or tingling near to the joint
Contact your hospital ward nurse or your physiotherapist who would liaise with your Surgeon. If it is at late hours in the night, you may have to attend the emergency department and see the on call Orthopaedic Doctor who would assess your knee and speak to your surgeon.