The knee is sometimes called the shock absorber of the body and is often, as you have found, the source of many complaints. You are certainly on the right track with your studies. But to answer your question, no, that advice is not sufficient. Leaving the student with advice on what not to do, without being able to alleviate concern or fear about discomfort or pain, plants a subtle seed of anxiety in the student. Try to develop a positive approach instead. Demonstrate and teach your students the proper techniques and tools to correct their problems. Leave them with their knee feeling some improvement. You can then caution them what not to do, but emphasize and show what to do for improvement first.
It may be helpful to carefully observe your student’s posture and alignment. Look at the ankle and hips, the joints above and below the knee. See if they are properly aligned, especially in regard to the knee. (Many asanasstanding poses, for examplecan be done with the support of a wall, chair, wall ropes, or other prop. Then the student can focus on proper alignment without worrying about balance.) Often, as the hips open more and more and the ankles become stable, knee problems dissipate. Only when you see that the hips and ankle are opening correctly can you do more work directly with the knee joint.
See that the student works to open and stretch the hamstrings and quadriceps, and to strengthen the muscles and improve flexibility in the legs and hips. Then the knee will become more stable and have improved freedom of movement.
Certified Advanced Iyengar instructor Dean Lerner is co-director of the Center for Well-being in Lemont, Pennsylvania and teaches workshop across the United States. He is a longtime student of B.K.S. Iyengar and served a four-year term as president of the Iyengar National Association of the United States. Known for his ability to teach yoga with clarity and precision, as well as warmth and humor, Dean has conducted teacher training classes at Feathered Pipe Ranch in Montana and other locations.