Nadal’s knees

Monday, September 3, 2012

There is a fine line that an athlete walks in practice between maximizing performance and pushing so hard that the body gets damaged. There is no good time to get hurt there are especially bad times. For Rafael Nadal, developing patellar tendinitis this summer was doubly bad, preventing him from participating in the Olympics in July and the US Open tennis championships at the end of August. The patellar tendon is barely two inches long but when it gets inflamed it can bring a world champion literally to his knees.

A quick anatomy lesson. When the quadriceps muscle contracts, the knee straightens. The muscle begins with an attachment to the ilium, one of the bones of the pelvis, then spans the hip and runs down the front of the thigh. Muscle cells gradually transition into tendon fibers called the quadriceps tendon, just above the kneecap or patella and then envelops the patella within the tendon fibers. It then continues, renamed as the patellar tendon, to attach to a bony spur on the front of the tibia, called the tibial tubercle. The quad muscle is balanced by the hamstrings on the back of the thigh to absorb the force of the knee through walking, running and jumping. But much of the mechanical load of landing is taken up by the patellar tendon.

In an ideal world, the body would be designed to tolerate all the force that a human could produce, but there are some design flaws. The kneecap can sometime be located a little higher or lower than normal, or the angle of the quad muscle as it attached to the tibial tubercle can be abnormal (think knock-kneed or bow-legged). As more weight is added to the body, the more stress is placed on the knees and their ability to absorb the shock of running and jumping. Maintenance issues having to do with tight muscles and poor quad and hamstring flexibility can affect tendon loading. And then there is technique, equipment and location that deal with the ability to land softly, have shoes that help cushion and ground that is soft. Any or many of these factors can cause the patellar tendon to become microscopically damaged and inflamed.

Imagine the stress that Mr. Nadal puts on his knees with quick stops and starts on a hard tennis court. Initially, he’ll experience pain only after a practice or match. The pain is due to microscopic stretching of the tendon fibers and is called a grade I strain. A little ice and ibuprofen causes the pain to subside, and as an elite athlete, he probably ignores the routine aches and pains associated with the hours of playing time each day. However, the pain will start to invade the exercise and while it really doesn’t affect performance, it lasts longer after the match and may make sleep harder to come by. But without enough treatment or rest, the inflammation becomes worse, the tendon fibers weaken and the tendon can partially tear, a grade II strain. Finally, the tendon can weaken enough that it ruptures (grade III strain) and an operation is needed to reattach the tendon ends to bone.
The magic treatment for patellar tendinitis is the same for other strains. Rest, ice and anti-inflammatories are the mainstay but it’s also important to understand what went wrong and try to fix it. Physical therapists understand the body’s biomechanics and can work hard not only on treating the existing injury but also preventing future ones. As with most things medical, the time invested in rehab early on pays dividends long term. With this injury, initial strains require at least a couple weeks of rest and as the severity of injury increases, the amount of rest time increase as well. A partially torn tendon, as suffered by Mr. Nadal may need 3 months or more of rest and rehabilitation before he can start practicing and some athletes need a year or more to return to competition.

As athletes aim for faster, higher, and stronger, the will to work hard may be trumped by basic anatomy and physiology. The mind cannot prevent a tendon fiber from ripping away from bone, even if it can force the body to reach a little further to return a tennis ball. But patience isn’t always a virtue shared by an athlete and taking time to rest may be the toughest challenge that Mr. Nadal may face in his career.

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