physical e xamination
A complete examination of the knee, including a careful
assessment of the patellofemoral joint, should be
performed (Table 312,13). The examination should
aim to identify features that may alter patellofemoral
mechanics.
Inspection. Patients initially should be examined “from
the ground up” while standing in shorts. Although the
clinical utility of static measurements of lower extremity
alignment appears to be limited, such measurements
may be performed at this point in the examination.
Observation of the patient’s gait may reveal excessive
subtalar pronation.
Dynamic patellar tracking can be assessed by having
the patient perform a single leg squat and stand. Imbalance
between the medial and lateral patellar forces (caused
by vastus medialis obliquus [VMO] dysfunction or lateral
structure tightness) can be manifested by an abrupt
medial deviation of the patella as the patella engages the
trochlea early in flexion, known as the “J” sign.13 Alternatively,
the “J” sign may be observed with the patient supine
or seated and the knee extended from a flexed position.
Lateral deviation of the patella can be observed during the
terminal phase of extension (Figure 2).18
Quadriceps muscle bulk, especially the VMO, should
be assessed by visual inspection and comparison with
the opposite side. Measurement of quadriceps muscle
girth can be used as a baseline in assessing progress with
rehabilitation. Any surgical scars should be noted.
Palpation. This portion of the examination should
be performed with the patient supine and the knee
extended. The knee should be assessed for an effusion.
A joint effusion is uncommon in PFPS and should
prompt evaluation for other causes of knee pain. Quadriceps
muscle tone can be assessed by direct palpation at
rest and with isometric contraction. Careful palpation
should be performed in an attempt to isolate the location
of the pain (Figure 1; Table 312,13). The ligaments
also should be examined as part of the comprehensive
examination.