Diagnosis
The symptoms of patellar tendinitis are relatively
easy to recognize. The patient will feel pain, not directly behind
their kneecap (as in the condition of chondromalacia), but just
below (distal to) it. Tenderness is present within the upper (proximal)
patellar tendon, and in particular where its mid-section attaches
to the lower end of the patella. The patient will typically feel
discomfort there if they are either trying to kneel directly on
their knee or if they are placing a lot of tension on their patellar
tendon. The latter occurs while running, jumping or when bending
the knee and supporting one's body weight at the same time (i.e.,
getting into a half-squat position). In very inflamed cases, local
warmth can actually be felt emanating from the tissues beneath
the skin overlying the patellar tendon. X-rays are almost always
normal, and only in advanced cases where significant structural
tendon degeneration has occurred are MRI scans (such
as the one shown in FIGURE 3) abnormal.
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FIGURE
3 - Advanced case of patellar tendinitis. This MRI
scan image shows a close-up, side view of the frontal region
of an actual patient's knee, with the lower half of the patella
("P", above) resting against the frontal portion
of the femur ("F", to the left). Below the patella
one can see the patellar tendon, running downward toward the
tibial tubercle (not seen). The normal portion of this patellar
tendon is solid black, and looks thin and straight (double
arrow). The afflicted, upper segment of tendon that attaches
to the patella is swollen and has lost its normal black appearance
(single arrow). The lighter shaded tendon tissue in the swollen
zone represents degenerated and broken down tendon fibers.
If very heavy stress is applied to a tendon in this condition,
it can rupture through the degenerated zone, suddenly and
unexpectedly. Urgent surgical repair would then be necessary. |
Because most cases of patellar tendinitis are not advanced,
and therefore not diagnosable with an MRI scan, general physicians
and even orthopedic surgeons may sometimes fail to identify this
common problem! While the symptoms of jumper's knee are not
hard to recognize if one listens carefully to the patient's
detailed description of what they have been experiencing,
specific diagnostic tests are often required on physical examination
to confirm the presence of this malady. If the knee is examined
for proximal patellar tendon tenderness at the wrong joint flexion
angle and/or with incorrect patellar posture, no tenderness may
be elicited and the diagnosis may therefore be missed. During
the course of rendering many second opinions over the years, I
have seen a number of cases where patellar tendinitis had been
mistaken for chondromalacia patella or knee arthritis, leading
to an initial recommendation for an unnecessary knee arthroscopy.
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