It is common (24%).
Synonym:
Tibial collateral ligament tear .
Definition:
It is the distension or the rupture of the two beams (superficial and deep) of the ligament, secondary to valgus stress.In general the rupture is high, at the femoral insertion.
Clinic:
Internal pain in valgus (grade I) with laxity (Grade II and III) in extension and especially at 20 ° flexion. An internal laxity in extension is seen in case of rupture of the LCA and the LCM. An isolated rupture of the LCM gives no internal laxity in extension.
MRI:
DP FS axial and coronal.
Thickening and hypersignal ligament ± fiber interruption.
The classification is as follows:
– grade I: non-fluid hypersignal of soft tissues and LCM which is thickened;
– grade II: hypersignal T2 in the LCM but the tendon remains continuous, no retraction;
– grade III: LCM continuity and proximal or distal retraction.
Evolution:
Healing is the rule, even in advanced stages, when it is an isolated lesion.
Treatment:
The rupture of the LCM associated with that of the LCA is due to the reconstruction of the LCA ± repair of the LCM.
Differential diagnosis
SIDE LIFTING:
It is often reduced when the subject presents himself at MRI.
It can be acute, macro-traumatic or related to objective patellar insufficiency (IRO) and lead to recurrent patellar instability.
Clinic:
Mechanism: valgus flexion external rotation. The patella is luxurious externally and the internal patellar fin (medial patellar retinaculum, RPM) breaks. There is haemarthrosis.
Standard radiography:
Search for associated fractures (medial patellar crest, external trochlea).
MRI:
It allows to correct a false diagnosis of a recurrent internal sprain: reaching the posterior part of the RPM whose insertion is identical with that of the LCM can simulate a sprain of the LCM on the coronal sections in particular. There are three signs of a posteriori diagnosis of patellar dislocation: axial cuts are the most interesting:
– hypersignal contusion of the internal patellar facet;
– hypersignal of the RPM, more anterior than the LCM. The posterior coronal sections show the normality of the LCM;
– contusion of the external trochlean bank.
Treatment:
Immobilization in slight flexion 4-6 weeks.
OEDEME:
Edema around the LCM can occur in osteoarthritis, a simple recent trauma, a lesion of the MM or an osteoarthritic expulsion, or even a painful patellar syndrome.
This sign is therefore not specific to a LCM sprain.
A RELATED ASSOCIATION OF THE LATERAL COLLATERAL LIGAMENT:
Synonyms:
Lateral collateral ligament tear , fibular collateral ligament tear.
Definition:
Partial or complete distension or rupture of LCL after varus stress ± associated with external rotation.
Clinic:
Posterolateral pain with laxity in varus. There is posterolateral rotational instability if other structures of the IPO are injured. Intra-articular effusion in the case of intra-articular lesion (LCL is extra-articular and non-adherent to the lateral meniscus).
MRI:
DP FS coronal and axial ± sagittal. The classification is the same as for the LCL.
Hypersignal fibers that are more or less discontinuous and thickened . The rupture is rather proximal.
Evolution:
LCL lesions heal more slowly than LCM lesions. The phases and stages of healing are the same for all ligaments:
– stage 1: inflammatory (first 3 days). Fibroblasts produce collagen type III;
– stage 2: repair and regeneration (6 weeks). Type I collagen replaces type III;
– stage 3: remodeling (up to 1 year after trauma).
Treatment:
Isolated breakage: preservative (splint in extension 2 weeks).
In case of associated lesion: restorative surgery.