Medial Collateral Ligament injuries (Knee)

Medial Collateral Ligament (MCL) Injuries of Knee

Definition:

The medial collateral ligament (MCL) of the knee is a ligament (Figure 1) that helps stabilize the knee from valgus stress and prevents over separation of the medial femoral condyle from the the medial tibial plateau.   MCL injuries of the knee most commonly involve the proximal portion of the ligament.  However they can be associated with midportion where the MCL attached to the medial meniscus and the distal portion of the the ligament that lies deep to the pes anserine.  The MCL originates from the medial femoral condyle and inserts on to the anterior proximal medial tibia.  It crosses over the medial joint where it forms a meniscocapsular attachment (See Figure 2 – Coronal MRI of knee)

Figure 1 – Medial Collateral Ligament of Right Knee

Figure 2 – MRI of Left knee (coronal view:  normal MCL and medial meniscus) Right – MCL black line – Left MCL hilighted in yellow

Injury Mechanism: The medial collateral ligament can be injured when the knee is forced into valgus stress in a variety of degrees from full extension to full flexion.

Grading of MCL injuries (2,3,4):

1 – Sprain of ligament: – 0-5mm laxity (3), or pain and minimal laxity with valgus stressing (4), with no evident tear or minimal tearing on imaging (MRI – may show peri-ligamentous edema).

2 – Partial tear of ligament: laxity at 30 degrees but no laxity at 0 degrees (+-pain)(4), superficial ligament on MRI (tearing of superficial fibres of MCL, deep fibres intact) 5-10mm laxity (3),

3- Complete rupture of ligament: Laxity at 0 and 30 degrees.(4)  This may include avulsion OR complete disruption of superficial and deep ligaments)  – 78% were associated with other injuries (most commonly ACL) (1) 10+mm laxity

Differential Diagnosis:

Strains/tears of medial hamstrings distally (semimembranosis, semitendinosis), Medial meniscal tear, medial meniscal cyst, pellegrini-stieda lesion, medial patellar-femoral ligament sprain/tear, pes anserine bursitis, medial tibial plateau fracture, medial knee osteoarthritis, osteochondroma

Exam:

Inspection: There may be some swelling over proximal or distal MCL.  A joint effusion may be present if there’s an associated injury.
AROM – In acute phase pain is usually evoked with active extension at end range of knee
PROM – In acute phase pain can be usually evoked with passive extension at end range as well as valgus stress.
AROM v. Resistance:  May be some weakness due to inhibition secondary to pain with quad extension.
Hamstring flexibility:  Tested with hips at 90 deg flexion – typically the affected MCL injury side will exhibit a tighter hamstring but not always.  This may become more evident a few days after the injury.

Classic teaching describes – applying a valgus stress at 0 and 30 degrees knee flexion to assess for laxity as well as pain on the medial aspect of knee.   Occasionally with MCL grade 1’s, athletes may exhibit a normal above exam but still describe pain with applied forced external rotation of foot.

Dynamic MCL Knee Exam (MCL and posteromedial corner)5:

It is important to check for associated injuries by examining the entire joint.  However especially important to include meniscal testing and assessing the ACL.

Imaging:

Xray – can be helpful to visualize associated injuries, a MCL avulsion fracture or in rare circumstances where an MCL injury develops a calcification such as a pelligrini-stieda lesion.  It is also possible to do stress views (5)

Ultrasound – As the MCL is superficial, US can determine whether there’s a tear and the stage as well

MRI – Excellent modality for grading the MCL injury but also assessing associated injuries, such as meniscocapsular dissociation, meniscal tears, and anterior cruciate ligament (ACL) tears.

CT – is limited to visualizing avulsion fractures in relation to isolated MCL injuries (5)

Management:

Conservative:  Bihinged stabilizer brace (1) Physiotherapy – early mobilization with active and passive range of motion, hamstring flexibility and graduation of neuroproprioceptive control.  All grades of MCLs may be treated successfully conservatively, however associated injuries such as ACL may need to be surgically repaired.

Prognosis for return to play, based on literature (in brackets the recommendations as per author’s experience with these injuries is that they take longer to heal than the literature suggests)
Grade 1 – 10.6 days (6) – (author suggests 2-3 weeksif returning to play before this strongly recommend protection with bihinged bracing or taping)
Grade 2 –  19.5 (6) – (author suggests 3-6 weeks – if returning to play before this strongly recommend protection with bihinged bracing)
Grade 3 – 4 weeks (7)- (author suggests 8 weeks (1), if returning to play before this strongly recommend protection with bihinged bracing)

Surgical:  Acute repair is an option for athletes depending on timing and situation for grade III injuries.  In patients with chronic laxity surgical reconstruction may also be considered (1) and any grade 3 MCL injuries with associated injuries (mainly ACL tears) would also be candidates for surgical repair.

Dr. Neil Dilworth (Sept 30, 2017)

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