Athletic Injuries 101: Meniscus Injury

Chatham’s Dr. Sarah Ytsma explains the definition, causes, signs and symptoms, and treatments for a meniscus injury in this month’s edition of Athletic Injuries 101.

DEFINITION: We have 2 menisci in the knee; one medial or inside, and one lateral.  The meniscus is a “c/o” shaped piece of fibrocartilage that provides flexibility in the socket of the knee, increases knee stability, accommodates sliding and rotation at the knee as well as friction, and decreases compression on the joint space.

A normal  meniscus will account for approximately 40-90% of the load across the knee and helps to direct compression on the knee, outwards to the joint capsule. When injured they are “poor healers”, especially if the inner 2/3 of the meniscus is injured, because of a poor blood supply. Unfortunately as we age, vascularity within the knee will decline.  The medial meniscus is injured approximately 75% of the time in athletes.

MECHANISM OF INJURY:

The medial meniscus is quite fixed as it attached to the Medial Collateral Ligament, while the lateral meniscus is more mobile and therefore, injured less. The meniscus is designed to slide anteriorly or towards the front of the knee when we straighten the leg, therefore, sliding back when the knee is fully bent.

The following are potential causes/mechanisms for injury:

1. Traumatic or excessive motion at the knee – sprain (mild to severe)

• hyperextension –> this will pinch both the menisci, and tense up 2 ligaments
• hyperflexion & internal rotation –> distorts the posterior horn of the medial meniscus
• hyperflexion & external rotation –> distorts the posterior horn of the lateral meniscus
• valgus force (think of someone being forced to be “knock-knee”) –> pinch the lateral meniscus
• varus force (think of someone being forced to be bow-legged) –> pinches the medial meniscus

2. Degeneration – some begin as a small, asymptomatic tear and later progress to a larger, symptomatic one

3. Repetitive or sustained weight bearing or deep knee bends (weight lifters, catchers in softball/baseball)

4. A combined compression (knee bent) and rotation injury or repetitive rotational stress.

SIGNS & SYMPTOMS:

1. Pain is usually rapid onset  and related to a specific event.

2. Often characterized by a small, painful click or snap

3. Pain may be localized to the joint line — this is considered a red flag

4. Decrease range of motion, especially extension or straightening

5. Knee locking & catching are red flags, indicating a large/significant meniscal tear or other joint occupying lesions — pinching pain, giving away or weakness

6. Swelling may occur in only about 50%

7. May experience popping or grinding afterwrds

8. Increased pain with twisting, squatting, stairs/inclines

9. Weakness/wasting of the vastus medialis muscle (inner part of quadricep muscle)

10. Often presents with night pain

TREATMENT:

An x-ray is not the best diagnostic tool to view a meniscus tear or sprain other than to rule out a joint pathology.  MRI or CT Scan is prefferd as they will show the soft tissue better.

Unfortunately, cartilage heals slowly & poorly due to poor vascularity (blood flow).  Large tears with significant pain/swelling should be referred to an orthopedic surgeon.

Injury Care:

1. RICE protocol combined with electrotherapy to help reduce pain and swelling

2. Taping or an elastic wrap/sleeve may help with stabilization and protection as needed

3. Activity must be modified, stopping activities that involve a lot of jumping, twisting at the knee, side to side movements/direction changes and speed changes, high impact on hard surfaces.

4. Mobilization/manipulation of the tibia/fibula — abnormal motion of these bones may interfere with meniscal motion.

5. Wearing good shoes to control excessive pronation at the foot to help reduce internal rotation of the tibia