- Relevant Anatomy and Biomechanics
- Mechanism and Causes of Meniscal Injury
- Clinical Presentation of Meniscal Tear
- Types of Meniscal Injuries or Meniscal Tears
- Differential Diagnoses
- Laboratory Studies
- Treatment of Meniscal Injury
- Rehabilitation after surgery
- Recovery after Meniscal Tear
Meniscal injuries or meniscal tear are common sports-related injury among adults. These are less common in skeletally immature persons and very rare in children younger than 10 years.
The injuries are more common in males than females.
The second peak of incidence is observed in elderly persons older than 55 years secondary to the degenerate meniscus.
Relevant Anatomy and Biomechanics
[Read anatomy of the knee]
The menisci are C-shaped wedges of fibrocartilage located between the tibial plateau and femoral condyles.
The medial meniscus is larger and is attached more firmly than the lateral. The anterior and posterior horns of both menisci are secured to the tibial plateaus. The transverse ligament connects the two menisci anteriorly and posteriorly.
The meniscofemoral ligament stabilizes the posterior horn of the lateral meniscus to the femoral condyle.
The peripheral meniscal rim is loosely connected to the tibia by the coronary ligament.
The periphery of each meniscus is attached to the joint capsule. The attachment is firmer in case of the medial meniscus.
Popliteus muscle tendon passes through a defect in the attachment of the joint capsule to the lateral meniscus, popliteal hiatus. Contraction by the popliteus during knee flexion pulls the lateral meniscus posteriorly, avoiding entrapment within the joint space. The similar muscular attachment lacks on the medial side.
During motion, the firmly attached medial meniscus moves only by few millimeters whereas lateral meniscus may move at least 1 cm.
The blood supply to the menisci is by parameniscal capillary plexus supplying the synovial and capsular tissues. This anastomosis is formed by branches of my medial and lateral geniculate arteries. This supply is responsible for blood supply to the peripheries [10-25 percent] whereas rest of meniscus derives nutrition from synovial fluid.
The tear in the area supplied by arteries is called red tear and in a non-vascular area are called white tear.
A red tear heals better.
A classification system based on a red or white tear is given below.
A tear in the vascular periphery completely is called red-red tear. Both sides of the tear are in tissue with a functional blood supply, a situation that promotes healing.
A tear encompassing the peripheral rim and central portion is called a red-white tear. One end of the lesion is in tissue with good blood supply, while the opposite end is in the avascular section.
The tear is exclusively in the avascular central portion and the prognosis for healing in such a tear is poor.
The classification has a bearing on the repair. Repair of lesions in the red zone has yielded good results
The menisci follow the motion of the femoral condyle during knee flexion and extension.
During extension, the femoral condyles exert a compressive force displacing the menisci anteroposteriorly. As the knee moves into flexion, the condyles roll backward onto the tibial plateau. The menisci deform mediolaterally, maintaining joint congruity and maximal contact area. As the knee flexes, the femur externally rotates on the tibia, and the medial meniscus is pulled forward.
The menisci directly influence the transmission of forces, distribution of load, amount of contact force, and pressure distribution patterns.
Mechanism and Causes of Meniscal Injury
Meniscal tears are caused by twisting motions [rotational forces with the knee in a flexed position and varus or valgus forces] like pivoting in basketball.
When the foot is planted and the femur is internally rotated, a valgus force applied to a flexed knee may cause a tear of the medial meniscus. A varus force on a flexed knee with the femur externally rotated may lead to a lateral meniscus lesion.
Chronic or repetitive stress also may cause degenerative tears of the menisci.
Most commonly, meniscal injuries are due to a traumatic event (especially in athletes). Meniscal tears also occur due to degenerative changes in older individuals.
Clinical Presentation of Meniscal Tear
Acute joint-line pain, gradual joint effusion are initial symptoms. Locking is a common symptom after a meniscal lesion develops. Locking usually occurs at 20-45° of joint extension.
A sensation of giving way may be reported.
Gait pattern may indicate a deviation or compensatory movement.
Knee effusion is often seen. There may be atrophy of the quadriceps femoris muscle.
Medial or lateral joint line would be tender depending upon the medial and lateral injury.
All the bony landmarks are palpated for integrity and range of motion is checked
Girth measurements allow for a general assessment of effusion and atrophy. The other limb is used for reference.
Special Tests for Meniscal Tear
It refers to point tenderness along the medial aspect of the joint line which increases with internal rotation and extension of the tibia. Indicates medial meniscus tear.
First Steinmann sign
With the patient supine and the hip and knee flexed to 90° the examiner vigorously and quickly rotates the tibia internally and externally. Pain in the lateral compartment with forced internal rotation indicates a lateral meniscus lesion.
Similarly, pain in the medial-compartment during forced external rotation indicates a lesion of the medial meniscus.
Second Steinmann sign
This is done when the tenderness is most pronounced along the anterior joint line.
When the knee is moved from extension into flexion by the examiner, the meniscus is displaced posteriorly, and the point of tenderness is displaced from the anterior joint line back towards the collateral ligaments.
This test can differentiate meniscal injuries from ligamentous problems, as ligament pain does not shift with flexion.
The patient sits cross-legged. Pressure is exerted along the medial aspect of the knee. Medial knee pain indicates a posterior horn lesion of the medial meniscus.
With the patient supine and the knee in maximum flexion, palpate the posteromedial margin of the affected knee joint with one hand and support the foot with the opposite hand.
Externally rotate the lower leg as far as possible, apply varus pressure, and cautiously extend the knee joint.
An audible, palpable, and painful clunk indicate medial meniscus tear.
To check the lateral meniscus, the hand is over the posterolateral aspect of the knee and internally rotate the lower leg to its maximum extent.
Slowly extend the leg again, listening and feeling for a click or pop.
With the patient in the prone position, flex the knee to 90°.
Stabilize the patient’s thigh against the examination table with the knee of the examiner, and apply a downward-directed force onto the patient’s foot and leg. Rotate the leg while mildly flexing and extending the knee joint.
Now repeat the test with the distraction of the knee instead of the compression.
If the rotation plus compression is more painful or shows decreased rotation relative to the normal side, the lesion is most likely to be a meniscus injury. If it is true in distraction, the cause is most likely ligamentous.
The patient stands first on the good leg, and then on the symptomatic leg, with the knee in 5 degrees of flexion and again with the knee in 20 degrees of flexion. Next, the patient rotates the body internally and externally 3 times, and the test is considered positive if there is joint line discomfort and/or a sense of locking or catching.
The patient assumes a squatting position with the lower extremities held in maximum external rotation [to detect a medial meniscal tear] and repeat in the maximum internal rotation (to detect a lateral meniscal tear). Pain and/or an audible click are positive findings.
Bounce Home test
The patient is supine with his or her heel cupped in the examiner’s hand.
The examiner fully flexes the knee and then passively extends the knee. If the knee does not reach a complete extension or has a rubbery or springy end feel, the knee movement may be blocked by a torn meniscus.
The patient is instructed to squat with the knee fully flexed and attempt to “duck walk.”
Pain or blockage of the motion indicates meniscal lesion. Pain is also seen in patellofemoral joint involvement.
Instruct the patient to stand with his or her knees extended and to rotate the trunk. This movement causes compression of the menisci.
Medial compartment pain during internal rotation of the tibia indicates a medial meniscal lesion. Lateral compartment pain occurring during external rotation of the tibia indicates a lateral meniscal lesion.
Modified Helfet test
The patient sits on the edge of the table and knee is flexed to 90 degrees. The patient is instructed to extend the knee.
Normally, in flexion, the tibial tuberosity can be seen in line with the midline of the patella in full flexion. During extension, the tibia rotates and the tibial tubercle moves into line with the lateral border of the patella.
Failure of the tibia to rotate during extension indicates a meniscal lesion or cruciate ligament involvement.
With the patient prone, the examiner flexes the knee 90°. The examiner rotates the tibia internally and externally twice, then fully extends the knee and repeats the rotations.
Increased pain during rotation in either or both knee positions indicate a meniscal tear or joint capsule irritation.
Types of Meniscal Injuries or Meniscal Tears
Meniscal tear types include
Longitudinally oriented tears
- Horizontal tear (cleavage tear) – The tear is parallel to the tibial plateau
- Longitudinal tear (vertical tear) – The tear is perpendicular to the tibial plateau and parallel to the long axis of the meniscus
- Wrisberg rip are longitudinal vertical meniscal tears occurring at the at the junction of the ligament of Wrisberg and the posterior horn of the lateral meniscus and are commonly associated with anterior cruciate ligament tears.
Tear perpendicular to the tibial plateau and the long axis of the meniscus For example root tear is radial-type tear located at the meniscal root
combination of all or some of horizontal, longitudinal and radial-type tears
Tear involving a component that is displaced, either still attached to the parent meniscus or detached:
- Flap tear: displaced horizontal or longitudinal tears
- Bucket-handle tear: displaced longitudinal tear
- Parrot beak tear: displaced radial tear
The severity of the symptoms can vary for different types of meniscal tears. A bucket-handle tear may cause the knee to lock and be quite painful, whereas a small vertical or radial tear that displaces may cause occasional symptoms of giving way and only mild pain
These include the following:
- Collateral ligament injuries
- Loose bodies in the knee
- Osteochondritis dissecans
- Cruciate Ligament injury
Routine blood tests are not required for diagnosis. In cases of arthrocentesis, the fluid may be sent for detailed investigation.
In pure meniscal injuries, x-rays are normal. On plain radiographs, meniscal tears are not visible.
MRI is the imaging of choice when a meniscal tear is suspected, with sagittal images being the most sensitive.
Each type of meniscal tear has its own characteristics but often following findings are seen.
- T1 – A hyperintense line in the meniscus can be seen.
- T2 – A hyperintense line in the meniscus, which indicates synovial fluid in the meniscus
Associated features that are suggestive of a meniscal tear include tibial subchondral bone edema, meniscal cyst
- Parameniscal cyst
- Meniscal extrusion
Treatment of Meniscal Injury
Non-operative versus Operative treatment for Meniscal Tear
There are several factors which need to be taken into account when deciding whether one should be treated by conservative treatment or needs surgery.
These factors are the severity of the symptoms and ability to perform one’s activity.
An individual with significant symptoms definitely would require surgery [locked knee or debilitating pain]. A person with an evidence of meniscal tear also needs to be operated.
However, a person with mild symptoms of a meniscal tear and who do not participate in sports may be given a trial of conservative treatment.
In the case of a sportsperson, if the ability to compete is impaired because of the symptoms, then nonoperative management is unlikely to be successful.
Studies have reported arthroscopic knee surgery and physical therapy to bring greater pain relief than does physical therapy alone.
Non-operative Treatment of Meniscal Injury
A reasonable goal before return to athletic activity is the strength of the injured lower extremity within 20-30% of the contralateral side. A smaller tear and tear on the outer edge of the meniscus in a stable knee, nonsurgical treatment may suffice.
The treatment includes RICE protocol, non-steroidal anti-inflammatory medicines and is followed by rehabilitation. The rehabilitation process is similar to that described for post-meniscectomy cased.
Surgical Treatment of Meniscal Injury
If the symptoms persist with nonsurgical treatment or the symptoms are severe at the outset, a surgical treatment may be chosen.
Most of the surgeries are now performed arthroscopically. Open surgeries are rarely required. Surgical options are
In this procedure, the damaged meniscus tissue is trimmed away. The stress is on tissue preservation than removal.
If the type of tear dictates and meniscus is healthy, the meniscal repair should be done. Repair of meniscus prolongs follow up as recovery time for a repair is much longer than from a meniscectomy.
Once the initial healing is complete after the surgery, rehabilitation is started.
Rehabilitation after surgery
The rehabilitation outline is similar for both meniscus removal and meniscal repair. Full weight bearing is postponed until 4-6 weeks after surgery in case of meniscal repair.
The rehabilitation of patient of meniscus injury after surgery is as follows
Four to seven days after surgery, the patient is able to bear full weight [4-6 weeks after the repair]
Modalities used as needed to decrease pain or swelling are
- Heat/ice contrasts/ ice alone
- Transcutaneous electrical nerve stimulation (TENS)
- Electric galvanic stimulation
- Flexibility exercises for the lower extremity muscles.
- Range of motion exercises
- Strength exercises
- Gradual progress to return to sports.
Recovery after Meniscal Tear
Meniscus tears are extremely common but with proper diagnosis, treatment, and rehabilitation, patients often return to their pre-injury abilities.
- Mordecai SC, Al-Hadithy N, Ware HE, Gupte CM. Treatment of meniscal tears: An evidence based approach. World J Orthop. 2014 Jul 18. 5 (3):233-41.
- Yeh PC, Starkey C, Lombardo S, Vitti G, Kharrazi FD. Epidemiology of Isolated Meniscal Injury and Its Effect on Performance in Athletes From the National Basketball Association. Am J Sports Med. 2011 Nov 30.
- El Ghazaly SA, Rahman AA, Yusry AH, Fathalla MM. Arthroscopic partial meniscectomy is superior to physical rehabilitation in the management of symptomatic unstable meniscal tears. Int Orthop. 2015 Apr. 39 (4):769-75.
- Gauffin H, Tagesson S, Meunier A, et al. Knee arthroscopic surgery is beneficial to middle-aged patients with meniscal symptoms: a prospective, randomised, single-blinded study. Osteoarthritis Cartilage. 2014 Jul 30.
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