Dean Lerner's Reply:
In the case of joint replacement, it is a good idea to ask the students about any suggestions, restrictions, or contraindications expressed by their physicians. Even though such surgeries are common, individual circumstances may vary, and the type of prosthesis and other factors will affect flexibility and movement.
Particularly, see what degree of flexibility is safely possible with the replacement knee. This generally varies from 120 to 155 degrees of flexion, 110 degrees being considered functional albeit rather restrictive. Such information may be helpful in understanding the limitations and working with your students.
When teaching, pay special attention to each student's posture and alignment, particularly in the joints above and below the replacement joint. In the case of the knees, this means the ankles and hips (and lower and upper legs). When these are aligned properly, the student will feel no strain on the knees. If the student has tight hips or problems with her ankles, then the asanas should be modified so that these areas can properly open and stabilize, to prevent strain on or incorrect movement in the knees. Use a chair or horse for support so the student is stable, and pay attention to proper alignment.
Additionally, see that these students practice poses that extend and strengthen the hamstrings and quadriceps, which are generally weakened by surgery. If needed, support those poses requiring deep flexion, such as Malasana (Garland Pose), in which a block placed under the buttocks can remove weight or potential strain in the bending action. Such a practice will help stabilize and control the knee joint and maximize and develop a healthy range 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.