To have a good results with training is possible if the ligament is not with defect. or it is complete. In this case the training of uper knee muscles give good results in his size and stabilituy
The body adapts to the stimulus it is given. Contralateral training should help the nervous system adapt to improve strength and motor control to a certain extent. However, adaptation of the tissues of the injured knee to improve its tolerance to re-injury would require increasing its capacity to bear and transfer loads which would need direct training.
It would works for post-op patients while maintaining mobility restrictions for some reasons. But, I strongly agree for increasing capacity to biomechanics stress there should be a direct loading. Nice question! Keep up the good work!
Cross training can result in an increase in strength in the untrained limb. Untrained limb can "response" to the stress of resistance training but it will not "adapt". Although, key factor in resistance training and its subsequent adaptations is the motor units that activated under progressive load.
An excellent question. I think it works for some extent. The previous answers explained the mechanism and the extent of such training in details. However, we conducted a study on athletes with meniscus injuries, and some results were impressive. From my clinical experience, this training would benefit more younger athletes.