Rehabilitation, always an important—some would say crucial—aspect of orthopaedic care, has some common elements for all cases and then some specific elements that depend upon the location of the cartilage lesion. I like to say that physical therapy for cartilage reconstruction is site specific.
One common element is that post operative motion is, in general, thought to be beneficial for the repairing cartilage cells. This was originally shown by Dr. Robert Salter, and it seems to hold true no matter what the repair technique is. One way of encouraging rapid post operative motion is to use a “continuous passive motion,” or CPM device, which is essentially a slow moving sled that sits on the bed. It is quite comfortable for most patients, and is often used 6-8 hours/day (which can be while sleeping). In a typical case, the motion is gradually increased day by day by having the patient move a dial. Some cartilage procedures may be combined with other procedures (like tibial tuberosity osteotomy) that force us to restrict the motion for a while. Eventually, the goal is to get back full motion. These machines are usually used for two to three weeks.
During the motion phase, patients use two crutches and do not walk upon the leg. Squatting or stair climbing is forbidden. However, it is okay to balance slightly on the foot, or to rest the foot upon the ground. Some patients with cartilage defects underneath the kneecap are allowed to place even more weight on the leg at about ten days.
Isometrics, good leg control, and return of motion are the initial goals. The therapist can be very helpful during this time—but even if the patient meets these goals early, advancement of therapy must await the appropriate time! We do not want to put too much stress upon the graft when it is very early in the growth phase.
Sometimes these are called “open chain” exercises. In a few weeks, we convert to “closed chain” exercise, which means: increasing the load, putting the foot upon the floor. One effective way of doing this is to use a stationary bike at no load (like a flywheel) and then gradually increase the load. Swimming—especially treading water—is also a good method. At about six weeks progressive resistance exercises are valuable as we smoothen out the gait. Usually the patients are feeling very good at this time, and we have to hold them back from overdoing it—for months! There are many activities allowed, such as biking, elliptical training, swimming, but other activities such as running and contact sports, are usually not permitted for one year. In the professional athlete population, there is ample evidence that a return to sport too soon—even with a small cartilage defect—does not result in good play.