When elbow flexion is incomplete or weak because of having sustained a birth-related brachial plexus injury--or for that matter--related to another cause like polio, a nearby muscle and its tendon, can be transferred to restore functional elbow flexion.
A number of donor muscle options exist, but one of the most championed options involves a latissimus muscle transfer. I have extensive experience with this transfer--which can be used to restore not only elbow flexion, but also elbow extension and shoulder flexion, occasionally. We will discuss whether this procedure is an option ffor you during your appointment.