Common Knee Injuries- Meniscus Tears
Last week, we looked at the structure and function of the knee. This week, we begin our examination of common knee injuries. First up: meniscus tears.
As stated in last week’s blog post, the meniscus serves as a shock absorber between the femur and the tibia. The medial is more commonly injured, especially with MCL injuries. The lateral is less commonly injured, but is more often injured with ACL tears versus the medial meniscus. Mechanisms of injury include twisting or turning, trauma, and sometimes even squatting. Degenerative tears can also occur with aging. Tears are typically confirmed via MRI, but can be inferred from history (what happened when the symptoms started), symptoms, and special tests your physical therapist can perform. Symptoms of a meniscus tear involve pain, stiffness, swelling, catching or locking, giving way or buckling, limited range of motion (ROM), and subsequent weakness.
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The four most common tears are bucket handle, radial, flap, and horizontal. Bucket handle tears describe a rip down the middle of the meniscus (form front to back). The meniscus remains attached as a whole, but torn part floats towards the center of the knee like the handle of a bucket (still attached at the sides). While there is good blood flow in this area, it often needs to be repaired surgically. The good news is that is can often be reattached versus shaved off, and you can retain all of your shock absorber. Because tears here cause a portion of the meniscus to float towards the center of the knee, it gets in the way of the knee fully extending, causing what is known as locked knee (unable to fully extend). This type of tear is often a result of a twisting injury. Radial tears run perpendicularly from the inner rim of the meniscus out towards the edges. Radial tears tend to be in areas of poor blood flow, and often require surgery to shave and trim the affected area. Flap tears are a type of horizontal tear that result in the a piece of the meniscus being able to peel away from the rest, which can result in it getting caught places where it ought not to. This, too, usually requires surgical intervention. Other horizontal tears can result in the meniscus almost being torn in half (horizontally), resulting in one meniscus almost looking like two lying on top of each other. This is a common type of tear that often also requires arthroscopic surgery. If tears occur on the outer 15% of either meniscus, they have a better chance of healing on their own, as this area of the menisci is more vascularized. Tears in the remaining menisci may require surgery if symptomatic. Degenerative tears, which appear more like fraying at the inner edges of the menisci, are often not symptomatic, and may not require surgery.
Initially, your doctor will most likely advise you to follow the RICE protocol:
- Compression (with brace, kinesiotape, or an ace bandage)
- Elevation (keeping the foot above the height of the heart when reclined)
After the acute phase (whether form injury or after surgery), you’ll begin to gently reintroduce movement and function again by focusing on increasing active range of motion (AROM) and strength. Your physical therapist will guide you in what’s appropriate to do and when. Some examples include quad sets to work on straightening the knee and heel slides (with a strap and without) to work on bending the knee. It’s best to keep these motions in what physical therapists often refer to as relatively “pain-free” range. If you’ve had surgery, you will most likely have pain, so this won’t be entirely pain-free. If you already have pain at rest, then it’s best to do these movements in a range that will not make your pain levels spike. Once your able to do these without increased pain, you’re physical therapist will usually tell you you’re ready to move onto strengthening exercises. Here, you may introduce things like mini squats, step-ups, and leg raises (standing or lying down), terminal knee extension, leg press, and hamstring curls. You’ll be able to progress these exercises by increasing weight, Theraband resistance (latex free version here) and/or repetitions. You may also begin to incorporate some balance exercises here: shifting from two feet to one foot, then standing on a softer surface, then on elevé. You may even do balance exercises on a Bosu Ball, which is a great way to increase proprioception. You’ll eventually progress to things like jumping and hopping again, or running, but these are final steps in your rehab. Again, your therapist will be able to guide you through your recovery.
That’s it for meniscus tears. Stay tuned next week as we dive into ligament sprains and tears.
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