MCL injury Flashcards
Epidemiology /Etiology
MCL injuries mostly occur after an impact on the outside of the knee, lower thigh or upper leg, when the foot is in contact with the ground, and unable to move. The MCL on the inside of the knee will become stressed due to the impact, and a combined movement of flexion/valgus/external rotation will lead to tears in the fibres. The athlete might feel an immediate pain, and feel or hear a popping or tearing sound.
Mostly the deep part of the ligament gets damaged first, and this may lead to medial meniscal damage or anterior cruciate ligament damage
Grading
As with all the ligament injuries, the MCL injury is graded 1, 2 or 3 (this grade is given depending on the degree of sustained tear). A grade 1 tear consists of less than 10% of the collagen fibres being torn, with some tenderness but no instability. Most of the patients feel pain when we apply force on the outside of a slightly bent knee, but there are no other symptoms.
Grade 2 tears vary in symptoms and therefore they are broken down further to grades 2- (closer to grade 1) and 2+ closer to grade 3, but both of them count as having tenderness but no instability.
The pain and swelling are more significant than with grade 1 injuries. When the knee is stressed (as for grade 1), patients complain about pain and significant tenderness on the inside of the knee, moderate laxity in the joint is observed.
Obviously, this means that a grade 3 tear is a complete rupture of the MCL, resulting in instability. Patients have significant pain and swelling over the MCL. Most of the time they have difficulty bending the knee. As stated before a grade 3 tear results in instability, when the knee is stressed (as described above) there is joint laxity. Grade III MCL injuries have an extra scale to measure the extent of the instability. These are described from the amount of joint separation in the 30° valgus test, more information here
Grade 1 -
Symptoms
- mild medial pain
- possibility of swelling and limping -medial edema
- tenderness
Signs
- medial edema
- tenderness
Tests
positive abduction stress test
Joint Space
0-5mm
Grade 2
Symptoms
- moderate medial pain
- swelling and limping
- instability
Signs
- medial edema
- tenderness
Tests
- positive McMurray’s test (if meniscus is involved)
- abduction stress test
Joint Space
6 to 10 mm
Grade 3
Symptoms
- severe medial pain
- swelling
- knee gives way into valgus
Signs
- marked medial edema
- tenderness
Tests
Lachmann test for ACL stability should be accomplished when a grade III MCL instability is present.
Joint Space
> 10 mm
Difference between grades
Grade I and II injuries have well-defined end points contrary to a grade III tear that occurs a soft end point with valgus stress testing.
A grade 1 tear consists of less than 10% of the collagen fibers being torn. Grade 2 tears vary in symptoms and therefore they are broken down further to grades 2- (closer to grade 1) and 2+ (closer to grade 3). Obviously, this means that a grade 3 tear is a complete rupture of the MCL.
When the knee is stressed (as for grade 1), patients complain about pain, moderate laxity in the joint and a significant tenderness on the inside of the knee.
When we speak of a grade 3 tear of the MCL. patients have significant pain and swelling over the MCL. Most of the time they have difficulty bending the knee. Another common finding of a grade 3 tear is instability. When we stress the knee (as described above) there is joint laxity
A physical examination will help to ensure a correct diagnosis. A medial meniscal tear can be mistaken for an MCL sprain, because the tear causes joint tenderness like the sprain. With a valgus laxity examination a medial meniscal tear can be differentiated from a grade 2 or 3 MCL sprain. The presence of an opening on the joint line means the medial meniscus is torn. A grade 1 MCL is more difficult to differentiate from a medial meniscal tear. The differentiation can be made through an MRI or by observing the patient during several weeks. In case of an MCL sprain tenderness usually resolves, with a meniscal injury it persists.
When there is tenderness, but no abnormal valgus laxity, it could be a case of medial knee contusion. If the tenderness is situated near the adductor tubercle or medial retinaculum adjacent to the patella, the cause is more likely to be patellar dislocation or subluxation. Patellar instability can be differentiated from an MCL sprain with the patellar apprehension test. A positive result means there is patellar instability
Diagnostic Procedures
MCL valgus stress test
Swain test
Anteromedial drawer test
Tests
To examine the medial collateral ligament itself, the valgus stress test which consists of two parts can be used. First a valgus stress is applied on the knee with the knee in full extension. Second, the same test is performed but the knee is 30 degrees flexed. The objective of testing the MCL with the knee at both 0° and 30° of flexion, is necessary for assessing the medial joint space widening and feeling for a solid endpoint. During the test, it’s important that the foot is been held in external rotation so that the examiner does not overestimate the amount of laxity as a result of the knee moving from internal to external rotation . Any asymmetry is considered as a positive result of the test
Laxity to valgus stress with the knee at 0° indicates the possibility of a combined injury. This will be likely with an injury to the cruciates or posteromedial capsular structures
Swain Test
A second test may be performed to examine the medial collateral ligament namely the Swain test. This test examines the chronic injury and rotatory instability of the knee. The test is performed by flexing the knee into 90 degrees and externally rotating the tibia.
This position of the knee tends to a relaxation of the cruciates while the collateral ligaments are tightened . When pain is felt on the medial side of the knee, an injury to the MCL complex is probable.
An another test that can also be performed to assess the amount of rotational stability present and whether the injury involves only the superficial MCL and deep MCL, is the anteromedial drawer test.
Medical Management
Most of the isolated grade III injuries are based at the femoral site, and do not require surgery. An important test to see if surgery is needed, is to see whether the posterior oblique ligament (POL) and posterior capsule are damaged. Surgery also should be considered when the pes anserinus tendons are damaged.
Situations with injury over the whole length of the superficial layer are a complete injury of both the superficial and deep MCL from the tibia are typical injuries that are better treated with an operation.
Grade III injuries that are unstable in 0 degree extension do also fall into the category where an operation is recommended. In addition, we should note that a surgical reconstruction is recommended for isolated symptomatic chronic medial-sided knee injuries
