The Medial Collateral Ligament (MCL) comprises of both a superficial and deep portion, which work as medial knee stabilizes. In the United States MCL injury is seen to be rare with it only effecting 1 in 4000 athletes, typically occurring in sports such as skiing, ice skating, hockey and soccer. Majority of complete tear (grade III) MCL injuries will heal, however, if they are not rehabilitated appropriately will lead to a chronic knee instability.

The largest and important structure in the medial knee is the superficial MCL originating at the femur and inserting at two tibial anchor points which functionally act in different ways. Being aware of this anatomical structuring is important as instability can be seen with external rotation, valgus rotation or anteromedial rotation.
The deep MCL does not have a distinct structure, it is a thickened joint capsule deep to the superficial MCL.
MCL injury mechanism is typically associated external tibial rotation, valgus knee loading or a combination of the two leading to forces placed upon the knee which are above that which the body can tolerate.

Grade I – no significant medial compartment gapping, localized pain along the medial knee.

Grade II – significant gapping at the medial compartment with a definite end point and localized pain.

Grade III – No defined end point after application of valgus stress at 20deg of knee flexion

Rehabilitation
With the stronger evidence for pre-operative rehabilitation also came the development of more aggressive post-operative rehabilitation as opposed to the previous conservative approaches. Similar to the aims of the pre-operative rehabilitation programs, post-op programs aim to strengthen the knee joint and improve the proprioception around the joint. The most successful rehabilitation programs have been those which in compass home based activities and clinical setting elements. As well as the utilization of both open and closed chain activities specific to the muscles cross the knee joint.

There are multiple intrinsic and extrinsic factor which may impact an athletes return to sports however; most are expected to return to training in 6 -12months. A phased rehabilitation MCL program my look similar to the following:
PART ONE: Reduce swelling, return to full weight bearing and increase passive knee range of motion.

PART TWO: Improve proprioception, increase muscle strength in the quads and hamstrings while increasing passive knee extension.

PART THREE: Achieve better neuromuscular control and optimal strength within the lower limb.

PART FOUR: Return to sport specific exercises, movement patterns and multi-tasking activities while maintaining and improving stability of the knee through proprioceptive exercises.

 Operative Treatment
Acute injury associated with the MCL is indicated with knee dislocation or malalignment injuries and requires the direct repair of injured structures using sutures or a complete hamstring graft in reconstruction of the medial knee stabilizers.
Alternatively, those who present with chronic medial knee instability symptoms are required to undergo a number of operations including a femoral osteotomy to reduce the risk f over stretching the reconstructed ligament that will eventually be put in place.

It is important to realize that pre-injury functional limitations may still be present after rehabilitation has been complete. Medial knee instability should be both clinically and objectively assessed in any patient who has a suspected MCL injury. If instability is still present, then the use of surgical intervention and anatomical reconstruction is highly recommended.

References

Labanca, L., Laudani, L., Menotti, F., Rocchi, J., Mariani, P., Giombini, A., . . . Macaluso, A. (2016). Asymmetrical Lower Extremity Loading Early After Anterior Cruciate Ligament Reconstruction Is a Significant Predictor of Asymmetrical Loading at the Time of Return to Sport. American Journal of Physical Medicine and Rehabilitation, 248 – 255.

Laprade, R., & Wijdicks, C. (2012). The Management of Injuries to the Medial Side of the Knee. Journal of Orthopaedic & Sports Physical Therapy, 221 – 223.