Assessing the activities that cause pain helps the evaluator to further comprehend the amount of inflammation and a mechanism of injury. A true mechanism of injury is vague, and typically the result of a combination of factors. Ascending or descending stairs generally reproduce symptoms. Pain after prolonged sitting or walking can also be indicators of pathology. Sometimes a patient may describe a brief feeling of "locking", "weakness", or "giving way". Eifert-Mangine et al. state that particular emphasis should be placed on determining "...the type and level of activities and sports in which the patient participates (1992)." Changes in the type of training activities, such as stair work-outs instead of training on a track, may precipitate symptoms of patellar tendonitis.
Prior injuries to the knee and neighboring joints can also help with determining a cause of injury. For example, an injury to the ball of the foot could cause a change in an individual's gait pattern, producing abnormal biomechanical stresses on the patellar tendon which over time lead to the development of inflammation. In some situations it may be necessary to correct problems in a related joint in order to help alleviate pathology in the knee. In such instances, gaining knowledge of previous treatments for the present episode of patellar tendonitis may help to determine the course of action.
Observation and Palpation
Details gained from a thorough history help to guide
the palpation and visual examination of the patient. During this
portion of the exam attention should be focused on establishing the integrity
of various anatomical structures. Visually inspect for signs of:
everts
causing the talus to slide medially and plantarly. The final outcome
is a medial rotation of the body of the talus and a subsequent internal
rotation of the lower leg. This effect delays the necessary external
rotation of the lower leg during the following stages of locomotion.
The tibio-femoral joint must compensate by internally rotating the femur.
The result is an increased stress on patellofemoral tracking, displacement
of the patella laterally, and a straining of the patellar ligament.
Tiberio (1987) reports that this chain of events reaches its peak magnitude
during the mid stance phase of walking as the body's weight is shifted.
Q-Angle:
The resultant angle formed by the intersection of
the line of pull from the quadriceps and patellar tendon is termed the
Q-angle.
It is an indicator of the relative lateral insertion of the patellar tendon,
and reflects lower extremity alignment. Women have an average Q-angle
of around 15 degrees, while men generally have values of less that 15 degrees.
Factors that relate to increases in Q-angle are excessive femoral anteversion,
external tibial torsion, lateral displacement of the tibial tubercle, and
genu valgum (Carson et al., 1984). Theoretically, and increased Q-angle
produces an increase in the magnitude of the valgus vector and therefore
lateral patellar displacement. Microtears form in the pateller tendon
which can accumulate over time and produce symptoms of patellar tendonitis.
However, Tiberio proposes that a statically measured
excessive Q-angle is not a reliable indicator of increased probability
for the development of patellar tendonitis. He states that during
dynamic conditions the increased internal rotation of the lower leg, which
results from excessive pronation, serves to decrease the Q-angle.
Therefore, the ultimate stresses on the patellar tendon are relieved.
Quadriceps Function
The function of the quadriceps
muscles plays an obvious role in the tracking of the patella and the
magnitude of stresses applied to the patellar tendon. The relationship
of strength and function between the vastus medialis obliquus (VMO) and
vastus lateralis (VL) is of particular importance. Abnormal stresses
occur when:
Flexibility
The biomechanical factors in bony alignment mentioned
previously result from the static influences of genetics and dynamic influences
of the over-lying musculature. The later tends to be a more common
and correctable issue. A lack of muscular flexibility in the lower
extremity adversely effects the stresses placed on the patellofemoral joint
and the patellar tendon. In general, the assessment of the range
of motion in the following muscles should be addressed.
Patellar Tracking
Normal patellar tracking is present when the patella
glides smoothly in the femoral sulcus. Only a minor degree of lateral displacement
should be felt. More marked degrees of lateral movement are described
as lateralization, subluxation, and dislocation. Also assessed when determining
abnormal patellar tracking is the tilt of the patella. The medial
and lateral borders should be on the same level in full extension.
Lateral tilt (lateral border lower than medial) is a common finding in
pathologic knees.
Patella alta is a particular type of malalignment
characterized by a longer than normal patellar tendon. when examining
the patient seated with the knees flexed to 90 degrees, the patella actually
points upward toward the ceiling instead of outward toward the examiner.
Another indicator of the patella alta is the "camel back" sign where the
infrapatellar fat pad is in prominence distal to the patella.
Differential Diagnosis
In some cases, symptoms reported by the patient
may not agree with the objective findings of the evaluation. It is
then important to consider other possible injuries, and/or refer the patient
to a physician or specialist. Fox and Del Pizzo (1993) provide the
following injuries which may be confused with patellar tendonitis:
Synovial infrapatellar plica - can provoke locking sensations in extension and pain in superomedial or superolateral quadrant of the knee.Meniscopathies - can cause real locking episodes, sharp pain localized at the joint line and joint effusion.
Patellofemoral arthrosis and chondromalacia - possible to find anterior knee pain in squatting or jumping, without point tenderness; the "grinding" sign is often present.
Bursitis - among the four bursae around the knee joint (suprapatellar, prepatellar, subcutaneous, and deep infrapatellar) especially the deep infrapatellar bursitis can mimic jumper's knee; but it must be remembered that pain localized at the tibial tubercle (as in deep infrapatellar bursitis) is uncommon in tendonitis occurring beyond adolescence.
Fat pad inflammation (Hoffa's disease) - distinguished by swelling and pain occurring when the fat pad is squeezed.
Osgood-Schlatter and Sinding-Larsen-Johansson diseases - considered as peculiar types of traction tendonitis in adolescents; they are characterized by pain localized at the tibial tubercle or at the lower pole of the patella (very rarely at the upper pole) and by radiographic findings (see below).
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