Q: I am going to have a meniscus transplantation in two days. The surgeon briefly went over what to expect afterwards. Can you give me a few more specifics about the rehab part? What will I do? How long will it take? What should I be careful about?

A: Meniscal transplantation is increasing in popularity and use. It is especially helpful for the person who has had to have the native meniscus removed due to severe damage. Without the protective, load bearing and distribution benefits of the mensicus, the knee can develop early painful and debilitating arthritis.

The procedure isn't done on anyone. Patient selection is fairly important for a successful result. Patients are usually young (less than 55 years of age), not overweight, and in pain from the loss of the meniscus. Donor cartilage is used as the graft, a process called allograft transplantation.

Every surgeon has his or her own way of selecting the graft and putting it in place. Research shows that the best way to get optimal results with meniscal transplantation is to select the correct graft size for each patient, place the graft anatomically, and secure it in a way that promotes biologic healing.

Once that hurdle has been completed, the rehab piece becomes the focus of attention. At first, you will probably be in a full extension (no knee flexion or bending allowed) knee brace. Immobilizing the knee like this allows healing to take place without disrupting the graft.

You may be placed in a device called a continuous passive motion or CPM machine. The machine can be preset to allow only a certain amount of knee motion. The machine passively moves your knee by bending and straightening it several times each day.

In this way, the joint can stay fluid and without stiffening up but without the use of the muscles that could pull on the graft. The machine is adjusted to allow more motion as time goes by. According to reports of protocols typically used, you should have 90 degrees of passive knee flexion by the end of two weeks. Passive means the machine is moving you. You are not actively moving the knee yourself.

You will be instructed in all these things by a Physical Therapist. The Physical Therapist will also show you how to perform isometric muscle contractions. These exercises are started right away after surgery. Isometric means you will contract the muscles without moving the knee. The two most common exercises to start with are quadriceps setting and straight leg raises.

When the surgeon removes the external stitches, you can begin a pool therapy program. Again, the therapist will guide you through what you can do in the pool. With the elimination of gravity and the force/load of your body weight, you will be allowed to do many things in the pool that are not yet allowed on dry land.

After the first month, you will be instructed to start moving the knee yourself. At this point, more vigorous muscle contractions are added to the program. This is all done gradually but with the goal in mind of reaching full motion by the end of six weeks after the surgery. You'll probably be using crutches in the first six weeks.

At first, you won't be allowed to even put the foot down on the surgical side. At four weeks post-op, you will be allowed to gradually put a little weight on the foot, then increase weight-bearing bit by bit. By the end of six weeks, you should be able to put full weight on the leg without using crutches.

If you are involved in sports or other strenuous physical activity, you'll have to put these on hold for at least four months. Full contact sports are not recommended for a full eight months and then only if the therapist has progressed you through a sports-readiness program. Strength and motion testing will be done to confirm your readiness for return-to-sports.

What we have described is a general outline of what you might expect in the coming weeks to months. Each surgeon has his or her own protocol. For optimum results, it is always advised to carefully and closely follow what your surgeon recommends.

Reference: Maurilio Maracci, MD, et al. Meniscal Allograft Transplantation Without Bone Plugs. A 3-Year Minimum Follow-up Study. In The American Journal of Sports Medicine. February 2012. Vol. 40. No. 2. Pp. 395-403.