Knee arthroscopy (meniscal & cartilage injuries)

Pre-Operation

Knee arthroscopy is a commonly performed, minimally invasive procedure, and allows both diagnosis and treatment.

Knee arthroscopy is used commonly complaints such as meniscal tears, cartilage injuries, osteochondritis dissecans (in adolescents), osteochondral lesions or injuries, and other causes of mechanical symptoms within the knee, not amenable to non-operative treatment. On occasions it is also used for diagnosis, and planning future treatments for the knee, such as osteotomies.

On most occasions, patients will have failed a trial of non-operative treatment. However sometimes arthroscopic surgery is indicated prior to this, such as the unstable meniscal tear in a young patient amenable to repair while it has a blood supply. An MRI can assist in diagnosis in some cases, however it is not always required and MRI is not 100% accurate. Knee arthroscopy is the diagnostic tool closest to 100% accurate and also permits treatment of the problem at the same time, in most cases. Therefore and MRI is not always required. The decision to perform an arthroscopy is usually determined by the patient’s clinical presentation (history of symptoms, and findings on examination)

Operation

Knee arthroscopy is usually performed as a day procedure (out-patient) and the patient can usually at least partially bear weight following the surgery, with or without the assistance of crutches.

The procedure is performed in under sterile conditions, in an operating theatre, with the patient under a general anaesthetic.

Once the patient has recovered from the general anaesthetic they are allowed to go home under the supervision of a carer.

Intra-operative photographs of chondral cartilage on the ends of the femur

Cartilage damage is most accurately assessed by arthroscopy. This is more accurate than MRI in this regard. The surgeon will examine all joint surfaces and also probe (feel) the joint surfaces. Cartilage damage is graded, in order of increasing severity, as follows, Grade 0 being normal:

Grade 1 – softening (as a forerunner to breaking down) – see photograph a

Grade 2 – less than 50% loss of cartilage thickness – see photograph b

Grade 3 – 50-100% loss, and / or bone in the depths of fissures – see photograph c

Grade 4 – areas of bare bone with no cartilage cover, may be surrounded by areas of grade 3 damage – see photograph d

Repair of meniscus using all-inside technique

There are a number of different types of meniscal tears

Unstable meniscal tear causing mechanical symptoms

Meniscal repair or partial resection

There are two menisci in the knee, one on each side (medial and lateral). Their most important function is to act as a shock absorber and thus prevent early osteoarthritis in the knee. They are often injured during sports activities that involve rapid cutting and pivoting manoeuvres. It is essential to repair the meniscus whenever possible, rather than excising the damage part, as the meniscus plays an important role in stabilising the knee and preserving the function of the knee.

If there is a tear in either meniscus (medial or lateral), and the meniscus is in sufficiently good condition to repair, with a blood supply at the edges of the tear, Dr. Porter will repair the meniscus. This is done using a surgical technique which allows the surgeon to stitch the tear together during arthroscopic surgery. There is no incision and a lower risk of complications with this method. The torn meniscus still takes 6 weeks to heal and patients have to avoid all twisting, pivoting, uneven ground and deep squatting for that period of time.

If the torn component of the meniscus cannot be repaired, only the damaged portion of the meniscus, which is not functioning, is resected. Therefore the arthroscopy does not contribute to the loss of functional meniscal its. However resected the damaged portion or the meniscus is likely to alleviate mechanical symptoms attributable to it.

Potential
complications

Despite our best attempts, potential complications are a risk with any injury or surgical procedure. You need to be aware of these rare potential complications.

The more common ones are listed here, but please ask the surgeon if there are any you are particularly concerned about.

1. Infection

This is a very rare complication following arthroscopic surgery, less than 0.1%, but can be serious and may required a return to theatre to wash the knee out and a course of intravenous antibiotics.

2. Thromboembolism

Patients can develop a clot in the leg being operated on, following any mobilisation. This may occur as a result of the injury and / or the surgery performed. However the risk can be reduced with a blood thinner, and if there is an increased risk of this the patient will be placed on a blood thinner. Some patients have a predisposition to clotting, which they may not be aware of.

3. Recurrent meniscal tear

Although part of the meniscus may be removed at surgery, it is possible that further meniscal tears may occur. It is also possible that a meniscal repair may not work, when performed, despite the potential to heal. This can be hard to predict in a young patient, but Dr. Porter will err on the side of repairing menisci in young patients.

4. Wound problems

The small incisions, or portals, can bleed following surgery, despite being sutured close. There are many small veins in this area of the knee, especially on the inside (medial side), and they are not visible with the tourniquet on. However, they only cause temporary bruising, which although alarming, will resolve with time with no long-term problems.

5. Incomplete relief of symptoms

Patients may have symptoms attributable to both a mechanical cause, such as a meniscal tear or loose cartilage flap or fragment, as well as underlying degeneration or osteoarthritis. The arthroscope can only alleviate symptoms from the former, it cannot reverse the degeneration as it cannot replace cartilage and the latter does not re-grow.

Post-Operation

The post-operative instructions are available by clicking on the link below, in a printable PDF version.

https://www.cosm.net.au/wp-content/uploads/2018/04/Pt-instructions-post-knee-AS-copy.pdf

Rehab / Physio

In most cases where there has been a simple partial menisectomy, chondroplasty, removal of loose body or excision of place or fat pad, the goals of the rehabilitation are to reduce the pain and inflammation caused by the operative procedure.

Physiotherapy is often commenced prior to the first post-operative review with Dr. Porter, which is 8-12 days post surgery.

The early treatments include RICE principles and then exercises to restore the function to the knee.

The goal is not, and cannot be, to reverse any degeneration in knee, if present. However the procedure does improve symptoms caused by injuries such as those mentioned above, even in knees with degeneration. If performed carefully and correctly, the procedure does not remove any functional cartilage.

Cycling on a stationary is possible within few weeks, and deep water-based training when the wounds have healed completely.

Walking or jogging for exercises will be avoided for at least 3-6 weeks post surgery. However, often it is possible to make a graded return to running as soon as the strength and balance have been restored to normal.