The medial meniscus is “O” shaped and the lateral meniscus is “C” shaped. The medial meniscus is narrower in the front and wider in the back and thicker in the back than in the front, while the lateral meniscus is relatively uniform. The two lateral menisci are attached to the tibial plateau. The normal meniscus has low signal on both SE and gradient echo sequences, with hypertrophy at the edges and thinning nearer to the center. The medial meniscus is thinner and larger than the lateral meniscus, and is also more closely attached to the surrounding joint capsule. In the sagittal plane, the meniscus on both sides has a “bowtie” pattern at the marginal level of the joint, and at the intermediate level, the anterior and posterior angles of the meniscus are separated from each other in a wedge shape with small tips.
MRI can show different degrees of meniscus damage. Degenerative lesions or tears of the meniscus can be seen as high signal shadows within the meniscus. The former is most commonly seen in young people, as the intra-articular fluid fills the tear and MRI shows increased signal intensity at the tear. Horizontal tears are seen in older adults, where mucus-like degeneration occurs in the center of the meniscus, followed by a horizontal tear that shows high signal intensity on MRI. The interior of the fibrous meniscus contains linear or globular high-signal areas, and these high-signal areas indicate pathologic changes of mucus changes and meniscal tears.
In addition to signal abnormalities, meniscal tears may also present with morphologic abnormalities such as.
1, blunting of the meniscus tip.
2, Displacement of meniscal fragments.
3. Narrowing of the posterior angle of the meniscus so that the posterior angle is smaller than the anterior angle.
Stoller classification
Grade I signal exhibits an indefinite or spherical high signal shadow.
Grade II signal shows linear high signal, neither of which extends to the meniscal surface.
Grade III signals are linear or diffuse high signal and extend to the articular surface, i.e., meniscal tears. To reduce the false positive rate, high signal extending to the meniscal surface must be seen in both the coronal and sagittal planes to diagnose a tear.
Treatment of anterior cruciate ligament injuries of the knee
Anterior Cruciate Ligament (ACL) injuries: much more than we think, 1.6-1.9 ACL injuries per day/100 million people in the US, 433 ACLs per day nationwide
ACL injury: May cause meniscal damage, degenerative osteoarthritis, loss of knee function
ACL function: stops knee hyperextension, excessive anterior displacement of tibia on femoral surface, stops excessive internal and external rotation of knee, excessive internal and external rotation
Diagnosis: lachman test, axial shift test, 90% accuracy
MRI is the most correct method, but it is not necessary to perform it routinely.
Treatment: Related to the patient’s requirements, conservative treatment is only indicated for patients who do not require high functional recovery of the knee and who have no other tissue concomitant injuries.
2. The vast majority of patients should be treated surgically.
(1) With attached bone fragments – elective surgery is possible
(2) Other surgery 3 weeks after the injury (to reduce swelling)
The correct rehabilitation physiotherapy in between
(3) Simple suturing of the ruptured ACL is not very useful
(4) Strengthening implants: autologous, allogeneic, artificial tissues
A. Artificial tissues have been abandoned, allogeneic ACL is easy to pull and damage, autologous is best
B, the standard for the bone tendon bone Bin ligament
C, semitendinosus groove 4, semitendinosus + femoral muscle of the four bundle tendon is emerging 5, with the medullary MCL may not be at, but injury to the meniscus must be dealt with.