A RELATED ASSOCIATION OF THE MEDICAL COLLATERAL LIGAMENT:
It is common (24%).
Tibial collateral ligament tear .
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.
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.
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.
Healing is the rule, even in advanced stages, when it is an isolated lesion.
The rupture of the LCM associated with that of the LCA is due to the reconstruction of the LCA ± repair of the LCM.
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.
Mechanism: valgus flexion external rotation. The patella is luxurious externally and the internal patellar fin (medial patellar retinaculum, RPM) breaks. There is haemarthrosis.
Search for associated fractures (medial patellar crest, external trochlea).
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.
Immobilization in slight flexion 4-6 weeks.
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:
Lateral collateral ligament tear , fibular collateral ligament tear.
Partial or complete distension or rupture of LCL after varus stress ± associated with external rotation.
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).
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.
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).
Isolated breakage: preservative (splint in extension 2 weeks).
In case of associated lesion: restorative surgery.