Knee - ACL Injury

• Simple pain relief – usually paracetamol and/or an anti-inflammatory are sufficient. – Apply a compression bandage to the knee and elevate. Ice can be useful to reduce swelling; normally 10-20 minutes of ice per hour
• In general, if there are no other significant injuries in the knee it is safe to walk on the knee as pain allows. This is normally a gradual process of weaning crutches.
• It is also important to bend and straighten the knee to prevent stiffness and get ready for surgery if it is needed. Avoid rigid knee braces which keen the knee straight
• Make an appointment with a physiotherapist to start exercises for knee movement and strengthening.
• See an orthopaedic surgeon to have the knee assessed, have other injuries in the knee looked at and a plan made for the ACL either to have surgery or to try to avoid it. Dr Gieroba keeps appointments available for urgent assessment of knee injuries.

No. Some people are very lucky and the ACL heals in a functional position and continues to do its job. This is quite rare. In some people, despite some increased knee laxity, they have minimal symptoms and can get by without an ACL. Around about half of people by age 50 no longer have a functional ACL. A knee rehabilitation program directed by a physiotherapist can help strengthen and co-ordinate knee muscles to compensate for an ACL deficiency.
For people whose knee instability prevents them from doing what they need or want to do (sports, work, sometimes even just walking) they do benefit from an ACL reconstruction.

The ACL is like a rubber band and when it ruptures it stretches out and becomes damaged. Additionally, because the ACL sits inside the joint, cells which are trying to heal and repair the ACL get washed away by the normal joint fluid. Because the remaining ACL tissue tends to be no good, tissue is brought from elsewhere to replace the ACL.

The common graft options include the patient’s own hamstring tendons, the quadriceps tendon or the patellar tendon. All of these options have their own advantages and disadvantages. Other less commonly used options include allograft (from a deceased donor), or rarely a synthetic ligament.

Dr Gieroba is familiar with modern reconstructive techniques. In most cases he will use a hamstring graft – aiming to use only one of the tendons (semitendinosus) to make a 4-stranded graft. If this is thick enough then the other tendon is left alone. In some cases, the graft is too thin with a single tendon so the other tendon (gracilis) is harvested too. There is evidence that thicker grafts have a lower re-rupture rate. For some people, other graft options are a better choice and at your consultation the options are discussed.

Once the graft is prepared, the inside of the knee is assessed with an arthroscope and any other problems dealt with at the same time. A tunnel is then drilled in the tibia and the femur to pass the graft through the knee joint to recreate the original ACL position. Fixation is typically performed with a suture button device on the outside of the bone on the tibia and femur.

There is no such thing as a free lunch. Every graft option has its own advantages and disadvantages. These are discussed at the time of your consultation but in general, harvesting a hamstring results in some hamstring weakness, patellar tendon graft carries a risk of fracture and arthritis, quadriceps harvest results in some quadriceps weakness and using a deceased donor tendon has a higher re-rupture rate.

Typically when the ACL ruptures the next structure that stops the knee from dislocating completely is the meniscus. This is not what the meniscus is designed to do and around 50% of ACL injuries also cause some sort of meniscal tear. These meniscal tears can be stable and heal on their own, or they may need to be repaired at the time of ACL surgery.
Other ligaments can be injured too, most commonly the MCL or medial collateral ligament. This is a broad ligament on the inside (medial) side of the knee which stops the knee from bending sideways. The majority of MCL injuries heal well without needing surgery. Sometimes ACL surgery is delayed for 6 weeks to give the MCL a change to heal.
When the knee gives way, the femur and tibia crash into each other in an abnormal way. This often causes bone bruising which can remain painful for months. It can also damage and detach part of the smooth cartilage on the end of the bone. Loose cartilage sometimes needs to be reattached.

A knee with an ACL injury has an increased risk of arthritis in the long term. ACL reconstruction does not seem to reduce this risk. This is likely to do with the cartilage damage being caused by the injury itself when the ACL was first injured. Episodes of knee instability and giving way in an ACL deficient knee may cause further damage to the meniscus and joint cartilage.

Because the ACL is an important stabiliser to rotation, certain groups of patients benefit from an extra procedure to help control pivoting in the knee. Dr Gieroba decides this on a case by case basis, but certain risk factors such as having hypermobile knees, being young (< 25 years old), playing high risk sports, re-do ACL cases and patients with a lot of pivot instability are likely to benefit. The procedure involves a cut on the outside (lateral) side of the knee (around 5cm long), and a portion of the deep fascia of the leg is harvested and inserted onto the femur. It reduces the risk of re-rupture of the ACL graft in high risk patients from 11% to around 4% and does not affect the rehabilitation or over-tighten the knee. The downsides are that it involves an extra incision and takes around 15 minutes longer.

The rehab is long. The aim is for a return to sport at the 12 month mark once rehabilitation milestones are met and an MRI demonstrates successful graft healing. There is evidence that an earlier return to sport is associated with a higher re-rupture rate. A physiotherapist oversees the rehab and progresses you when you meet certain milestones.

Rehabilitation is progressed based on meeting certain milestones rather than being strictly time based however in general the timeline is:

• Day surgery or one night in hospital. Using crutches initially.
• 2 weeks – Walking without crutches as soon as the quadriceps muscle is functional again. Working on range of motion.
• 6 weeks – Reducing swelling and eliminating the limp, working on strengthening
• 3 months – Starting straight line jogging
• 6 months – Starting jumping, landing and running
• 9 months – Starting some sports specific training in a safe environment. Starting direction changes while running
• 12 months – Return to play

In general, all surgery has certain risks. These include bleeding, infection and blood clots. All are rare with ACL surgery and blood thinners tend to not be needed. Infection is rare but is typically treated with a wash out and antibiotics.
Important risks specific to the ACL include stiffness. One of the most important parts of early rehabilitation is to get the knee moving again as the insult of surgery tends to want to stiffen the joint. Some pain in the back of the knee with hamstring harvest or the front of the knee from general weakness can occur. There is also a risk of graft rupture. This could be due to a re-injury, returning to activity too soon, surgeon error or simply bad luck. A re-do reconstruction using a different graft is possible following failed surgery.
Dr Gieroba will have a detailed discussion about surgical risks at your consultation.

Surgery is an insult to the joint, as is the ACL injury itself. Both things happening too close to each other carries a risk of ongoing stiffness in the knee. In general, ACL surgery is delayed until there is enough knee movement to proceed to surgery safely. For most people this is within 6 weeks and can be as soon as 1 or 2 weeks. What we aim for is full extension of the knee, and bending to at least 90˚. Your physiotherapist can help with “pre-hab” which involves getting the movement back, then starting strengthening of the quadriceps and hamstrings ready for surgery.
Because the old ACL is being replaced with new tissue brought in from elsewhere, there is no significant urgency to get to the surgery straight away.