If you happen to be one of many curious denizens of the Internet familiar with the spicy meme culture, chances are, you’ve come across this particular phrase coined from a popular video game: “I used to be a <Insert occupation title here>, but then I took an arrow to the knee”.
Although the meme got its share of chuckles over its lifetime, knee injuries, in reality, are nothing to laugh at. The knee is a precious, yet fragile, part of the human body prone to sport-related injuries that push many athletes to early retirement. To be specific, this is due to problems involving the menisci of the knee.
The menisci (plural of meniscus) are the two “shock-absorbing” cartilages of the knee. They lie between the end of the femur (thigh bone) and the top of the tibia (shin bone), taking up what appears to be a space on plain X-rays.
Made of flexible fibrous tissue, these C-shaped structures provide a number of important functions, with a few being:
- Force distribution
In one sense, they’re kind of like your fingernails; most of its tissue is bloodless, with the limited blood supply extending about 10-25% from their attachment at their periphery. But in contrast, your meniscus contains living cells that are nourished by diffusion and nutrients in the knee joint fluid.
Alas, nothing gold can stay. As the meniscus ages, they lose elasticity. This sad but inevitable process is known as meniscus degeneration. Like an old rubber washer, they dry out and have a tendency to split and crack.
And unfortunately, the menisci do not show up on X-ray and are poorly visualized on ultrasound. Arthrograms (X-rays with injection of dye into the joint) are rarely used, having been succeeded by the less invasive, and more accurate, MRI scan.
And yet, MRI is still only a runner-up among its peers. Significant meniscal pathology was discovered in the absence of positive MRI findings many times in patients with classic symptoms.
The gold medal goes to arthroscopy, which is a minimally invasive surgical examination/treatment performed with an arthroscope through a small incision. This procedure will be discussed in detail later below.
A meniscus tear occurs when the load applied to the tissue exceeds its strength and flexibility. And unfortunately, the force required gets less as we age due to degeneration. As if the thought of aging wasn’t bad enough, right?
Tear patterns also change. The young individual with an acute twisting injury is likely to have a single, clean tear while an older person will likely have numerous splits and flaps on a background of softening cartilage.
Some of the symptoms include:
- Well-localized sharp pain along the inside or outside joint line of the knee
- Associated swelling, particularly with activity
- Clicking or clunking in the area of the pain
- Locking-up of the knee with inability to straighten it
There are different kinds and degrees of meniscus tear a patient could have. In connection, that means there are different types of procedure out there to treat them.
That Was Then
25 years ago, the symptoms of a meniscus tear meant a trip to the orthopaedic surgeon for an open menisectomy. And as you know, anything that ends with sectomy is often prone to make you cringe and gag. This isn’t an exception.
The knee joint was opened through a 4-5cm incision and the entire meniscus was removed. A particularly barbaric implement, the Smillie knife, (invented by an imposing Scottish surgeon), had a sharp, curved blade and a long handle, perfect for digging into the flesh and stripping the meniscus from the knee in a few seconds. Not only does this procedure sound like something pulled out from your everyday gore flick, it could also lead to early degenerative wear.
This Is Now
Fortunately, things have progressed since then.
The vast majority of meniscus surgery is now performed through the arthroscope, a fibre-optic system allowing excellent visualization and access to all areas of the joint. The meniscus can be seen and examined on the big screen in glorious technicolour – you may even get photos to take home!
A tear in the peripheral part of the meniscus can often be repaired. This is particularly true for longitudinal splits, the most common type in a younger individual. The repair procedure is much more complex and takes a lot longer than resection. It may require an additional incision and there are added risks of infection and nerve damage. In addition, the recovery is more prolonged. Patients would be kept on crutches and avoid bending the knee for 3-4 weeks after the procedure.
Success rates for meniscus repair are in the region of 80-90%, with the higher percentages occurring when the repair is done at the same time as an Anterior Cruciate Ligament (ACL) reconstruction, which is a tissue graft replacement of the ligament. In the event of failure, re-repair is possible.
Repairing the Unrepairable
The majority of meniscus tears aren’t suitable for repair. They’d be:
- Outside the vascular healing zone
- Too old
- Complex for repair
In this case, a simple resection of the torn portion is carried out. Usually, this only results in loss of 10-30% of the meniscus and is not associated with long-term problems such as arthritis.
Recovery is fairly swift. Patients could return to sports in 6 to 8 weeks, and sometimes earlier.
Inactivity leads to weakening! Participating in an exercise program is important to strengthen the specific muscles groups that support the knee joint.
A knee injury may also cause an altered gait pattern (walking pattern) which can lead to further muscle imbalances not only in the knee, but also the hip and ankle as well. Physiotherapy can help to identify these muscle imbalances and develop an exercise program to correct them. As well as developing an exercise program, physiotherapy may also include joint mobilizations to help restore normal knee joint range of motion.
Future advances will likely involve the use of tissue proteins that promote healing. Success with artificial or transplanted menisci has thus far been limited and is performed experimentally at only a few centers. So don’t count on it being a real solution anytime soon.
In the meantime, keep your knees under check; after all, it’s the only pair you’ve got.
If you’ve got a meniscus tear or you’re suffering from any kind of knee injury in general, the team of professionals at SEMI can assess your condition and offer you a wide variety of treatments to get you back on your feet. To learn more about what we can do for you, contact us today!
Anderson, James E. M.D. 1984 Grant’s Atlas of Anatomy. 8th ed. Baltimore: Williams and Wilkins
Stephen C. Reed
BM, BCh, MA, MSc FRCSC