Authors

Prof Leo Pinczewski MBBS, FRACS

Dr Keran Sundaraj MBBS, MSc (Trauma), FRACS, FAOA

Anterior Cruciate Ligament (ACL)

The anterior cruciate ligament (ACL) is a 38mm long band of fibrous tissue that connects the femur (thigh bone) to the tibia (shin bone). Its function is to control stability when performing twisting actions. The cruciate ligament is usually not required for normal daily living activities. However, it is essential in controlling the rotation forces developed during side stepping, pivoting and landing from a jump.  

The Classic History of Injury

The ACL is commonly injured whilst playing ball sports or skiing. Whilst playing ball sports, upon attempting a pivot, sidestep or land from a jump, the knee gives way. When skiing, the ACL is injured when the binding fails to release as the ski twists the leg. Patients frequently hear or feel a snap or crack accompanied by pain. Swelling commonly occurs within the hour. Often pain is felt on the outer aspect of the knee. The medial ligament of the knee joint may also be disrupted, resulting in severe pain and swelling about the inner side of the joint. 

Rationale for Treatment  

The goal of treating an injured knee is to return the patient to their desired level of activity without the risk of further injury to the joint. Treatment may be without surgery (conservative treatment) or with surgery (surgical treatment). Those patients who have a ruptured ACL and are content with activities that require little in the way of sidestepping (running in straight lines, cycling and swimming) may opt for conservative treatment. 

An update on the treatment can be found here in the NSORG newsletter.

The flow-diagram below is a suggested algorithm based on the consensus of multiple experts world wide. It is only one such algorithm and there is no ‘one size fits all’ approach that is appropriate.

Conservative Treatment  

Conservative treatment is by physical therapy to reduce swelling, restore the knee joint's range of motion and rehabilitate the knee's muscle power. Reflexes are necessary to protect the joint for routine activities of daily living. Building protective reflexes requires rehabilitation directed at 'proprioceptive' therapy.

The ACL can heal, albeit at a low rate. It is very rare to operate on the acutely injured ACL. Time is given to “pre-habilitate” the knee, and a reassessment is performed in 4-8 weeks. Conservative treatment should always be considered first and may be appropriate in:

• Patients without ‘functional’ instability (i.e. they can change direction without giving way)

• Age >35 years

• No desire to return to competitive/pivoting sports

Surgical Treatment 

Those patients who wish to pursue competitive ball sports or who are involved in an occupation that demands a stable knee are at risk of repeated injury resulting in tears to the menisci, damage to the articular surface leading to degenerative arthritis and further disability. In these patients, surgical reconstruction is recommended. However, studies have shown that this is best carried out on a pain-free, healthy joint with a full range of motion. In addition, there may be the circumstance of the ACL healing within a few weeks. Whilst the incidence of this low, clinical reassessment after a period of prehabilitation is required to determine knee stability. The decision for ACL reconstruction can then be made.

All reconstructive procedures for the ACL require a graft. Our reconstructive technique involves grafting the torn ACL with a collagen graft. This may include the use of your own hamstring tendon or a donor graft. The choice of graft is made between you and Dr Sundaraj at the time of consultation. The graft is secured using specially designed screws allowing secure immediate fixation of the tendon within the joint, allowing for a rapid rehabilitation. Our long term results suggest that stabilising the joint protects the menisci and lessens the risk of later osteoarthritic degenerative change. Although ACL reconstruction surgery has a high probability of returning the knee joint to near normal stability and function, the final result for the patient depends largely upon a satisfactory rehabilitation and the presence of other damage within the joint. Dr Sundaraj will advise regarding the return to sporting activity, depending on the amount of joint damage found at the time of reconstructive surgery.  

What is involved for you as the patient  

• Healthy patients are admitted on the morning of their surgery and discharged in the afternoon.

• There must be no cuts, scratches, pimples or ulcers on your lower limb as this increases the risk of infection. You should not shave or wax your legs for one week before surgery.

• Patients should cease smoking and taking the oral contraceptive pill one week before surgery.

• Sedentary and office workers may return to work approximately 2-5 days following surgery.

• Driving an automatic car is possible as soon as pain allows after left knee surgery. Should the right knee be involved, driving is permitted when you can walk without crutches.

• Physiotherapy is commenced immediately. Your physiotherapist will supervise strengthening and walking. By 7 days after surgery, you should be able to walk without crutches.

• Playing sport non-competitively or training is possible at 4 to 6 months. A return to competitive sport is permitted at 9-12 months following surgery, provided that there has been a complete rehabilitation.

Potential complications related to surgery  

• Pneumonia: Patients with a viral respiratory tract infection (common cold or flu) should inform the surgeon as soon as possible and may have their surgery postponed. Patients with asthma should bring their inhalers to the hospital.

• Deep vein thrombosis and pulmonary embolus: Although this complication is rare, a combination of a knee injury, prolonged transportation and immobilisation of the limb, smoking and the oral contraceptive pill or hormonal replacement therapy (HRT) all multiply to increase the risk. Any history of thrombosis should be brought to the attention of the surgeon. The oral contraceptive pill, HRT and smoking should be ceased one week before surgery.

• Excessive bleeding resulting in a haematoma is known to occur with patients taking aspirin or nonsteroidal anti-inflammatory drugs such as Voltaren, Naprosyn or Indocid and should be stopped at least one week before surgery.

Potential complications specifically related to your knee reconstruction surgery.  

• Postoperative bleeding and marrow exuding from the bony tunnel may track down the shin causing red inflamed painful areas. When standing up, the blood rushes to the inflamed area causing throbbing. This should ease with elevation and ice packs. This is a normal postoperative reaction and only delays short term recovery.

• Due to the skin incision, you may notice a numb patch on the outer aspect of your leg past the skin incision. The numb patch tends to shrink with time and does not affect the result of the reconstructed ligament.

• If your own hamstring tendon is used, the musculature will recover quickly, and tendon regrowth may be felt at 14 days following surgery. However, scar tissue forms around the reformed tendons. This may tear and is felt as a pop or tear behind the knee on the inner side. This will usually set your rehab back for a few days only and usually occurs before 6 weeks.

• Graft failure due to poorly understood biological reasons occurs in < 1% of grafts.

• Reinjury rates are specific to you based on anatomical and lifestyle factors. These will be discussed with you at the time of your consultation.

• Surgery is carried out under strict germ-free conditions in an operating theatre. Antibiotics are administered intravenously at the time of your surgery. Despite these measures, following ACL surgery, there is a < 1 in 400 chance of developing an infection within the joint.

As with all operations, if at any stage anything seems amiss, it is better to call for advice rather than wait and worry. A fever, redness or swelling around the line of the wound or an unexplained increase in pain should all be brought to the surgeon's attention. You can contact Dr Sundaraj by telephoning his staff during business hours or the Mater Hospital after hours. For any questions, please do not hesitate to contact our staff (02) 9437 5999 For after-hour assistance contact Mater Hospital (02) 9900 7300 Further information is available on our website