The knee joint has two menisci, a lateral and medial
They are fibrous cartilage
They rest on top of the tibia in shallow indentations
Functions of the menisci
Aid in lubrication and nutrition of the joint
Act as shock absorbers
Evenly distribute weight throughout the knee
Allows for smoother motions between the femur and tibia
By increasing the effective contact area between the femur and the tibia, the menisci lower the load-per-unit area borne by the articular surfaces.
Total meniscectomy results in a 50% reduction in contact area.
The menisci transmit central compressive loads out toward the periphery, further decreasing the contact pressures on the articular cartilage.
Half of the compressive load in the knee passes through the menisci with the knee in full extension and 85% of the load passes through the knee with the knee in 90 degrees of flexion.
Meniscectomy has been shown to reduce the shock absorption capacity of the knee by 20%.
The inner 2/3 of the menisci are avascular (without blood supply)
The remaining outer 1/3 is vascular (with blood supply)
Mechanisms of injury
An acute twisting injury from impact during a sport
Usually the foot stays fixed on the ground and the rest of body rotates
Getting up from a squatting or crouching position
Loading the knee from a fixed position
Injuring the meniscus
There are several types of tears
A loss of any part of the meniscus causes uneven weight distribution and can lead to early wear of the knee
The lateral meniscus is not attached as firmly to the tibia as the medial meniscus, making it less likely to become injured
Axial Limb Alignment
Varus malalignment tends to overload the medial compartment of the knee, with increased stress placed on the meniscus, and valgus malalignment has the same effect on the lateral compartment and lateral meniscus.
These increased stresses may interfere or disrupt meniscal healing after repair. Patients with limb malalignment tend to have more degenerative meniscal tears, which have been suggested to have an inherently poorer healing capacity. The use of an "unloader" brace has been recommended to help protect the healing meniscus, although no scientific data exist to support this approach.
Meniscal injury statistics
Meniscal injuries occur in 15% of ACL injuries
80% of patients with a history of ACL tears will likely tear their meniscus with incidences of instability of the knee
70.7% of meniscal injuries are to the medial meniscus
Almost all meniscal injuries- ages 20 and under are sports related 11 out of 12 cases
Ages 20-29, 64.5% were sports related
Ages 30-39, 30.6% were sports related
Ages 40-49 and 50-59 only 19.6% and 14.3% were sports related
What to look for?
Not all meniscal tears are symptomatic
If there are symptoms you could look for:
Pain along the joint line (tenderness)
Pain when squatting, kneeling or pivoting
Locking of the knee
Loss of full knee extension
How can the Physiotherapist help?
If there is a possible meniscal tear 80-90% of the time an athlete will remember the mechanism of the injury and may report a “pop” or a “snap”
You could ask the athlete if there is pain when weight bearing, or bending of the knee
You could also ask the athlete if they are having any locking in their knee or trouble extending the knee all the way
When there is a meniscal injury
As a Physio in the event of a meniscal injury you should
Ice the area in pain
Limit movement of the knee joint (rest)
Keep weight bearing limited to a tolerable level of pain for the injured knee
Sometimes a splint can be applied for comfort
There are two common ways that a meniscal tear can be repaired surgically : Open/Arthroscopic
There is also a non surgical option because the menisci are partially vascular they have the ability to heal themselves
Why choose surgery?
Surgery is usually advised for a few different reasons
The location of the tear, if the tear is in a avascular zone it will most likely not heal itself
If the tear is longer than 5-8mm
If the pain limits activities of daily living
Or if the individual is not happy with their level of function
Rehabilitation after Meniscal Repair
Current studies support the use of unmodified accelerated ACL rehabilitation protocols after combined ACL reconstruction and meniscal repair.
In tears with decreased healing potential (such as white-white tears, radial tears, or complex pattern tears), limiting weightbearing and limiting flexion to 60 degrees for the first 4 weeks have been suggested to better protect the repair and increase the healing potential of these difficult tears.
Rehabilitation after isolated meniscal repair remains controversial. The healing environment clearly is inferior to that with concomitant ACL reconstruction, but good results have been obtained with accelerated rehabilitation protocols after isolated meniscal repairs.
The more common technique is arthroscopic partial menisectomy, which consists of removing the torn fragment of the meniscus
This reduces irritation, but can effect the weight distribution in the knee
The other option is an arthroscopic repair, which requires suturing the meniscus back together
This option attempts to conserve the meniscus in hopes of preventing the early onset of arthritis
Rehabilitation after Meniscectomy
Because there is no anatomic structure that must be protected during a healing phase, rehabilitation may progress aggressively.
The goals are early control of pain and swelling, immediate weight-bearing, obtaining and maintaining a full ROM, and regaining quadriceps strength.
Road to recovery
Whether you choose the surgical or conservative approach, the rehabilitation is similar
The rehabilitation time frames can vary depending on the individual and the severity of the tear
The protocols may vary depending on the surgical approach and physician. A common protocol may include the following
Steps to recovery
The patient may be full weight bearing right after the surgery with or without crutches
Initial symptoms can be reduced using certain modalities and manual techniques
Stretching/ flexibility exercises focusing on hamstrings, quadriceps, hip flexors, hip adductors and calf muscles
Initial physical therapy
The first few sessions of physical therapy may consist more of modalities and some manual techniques to address inflammation, pain and ROM such as:
Scar and patella mobilizations
Passive range of motion for full knee flexion and extension
Retrograde massage to decrease swelling
Once pain and swelling are reduced the sessions mainly focus on increasing the strength and flexibility of the lower extremity as tolerated
The progression will vary depending on the individual
Some examples of stretching and strengthening exercises are illustrated in the following slides
Focusing on strengthening the muscles around the knee is essential in rehabilitation
Quad sets Straight leg raises (in all planes)
Heel raises Leg Curl
Balance can sometimes be compromised after an injury or surgery
Here are some balance exercises that can help
Progression to more dynamic sports specific exercises helps with the transition back into sports
Return to play
This can vary widely from athlete to athlete
When the athlete can participate in sport specific exercises without pain or weakness
Full ROM is apparent in the injured knee
Collaborate decision between athlete, physical therapist and physician
The prevention of meniscal tears is very similar to the rehabilitation
Research has shown that more flexible and stronger joints are less likely to get injured
The athlete would continue stretching and strengthening the lower extremities
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Gilbert, Rob. Ashwood, Neil. “Meniscal repair and replacement: a review of efficacy.” Trauma. 2007. Vol. 9 p. 189-194
Lento, Paul. Akuthota, Venu. “Meniscal injuries: A critical review.” Journal of Back and Musculoskeletal Rehabilitation. 2000. Vol. 15 p. 55-62
Boyd, Kevin. Myers, Peter. “Meniscus preservation; rationale, repair techniques and results.” The Knee. March 2003. Vol. 10 Iss. 1 p. 1-11
Brindle, Timothy. Nyland, John. Johnson, Darren. “The Meniscus: Review of Basic Principles With Application of Surgery and Rehabilitation.” Journal of Athletic Training. Apr-Jun. 2001. Vol. 36 p. 160-169
Drosos, G.I. Pozo, J.L. “The causes and mechanisms of meniscal injuries in the sporting and non-sporting environment in an unselected population.” The Knee. April 2004. Vol. 11 Iss. 2 p. 143-149