- See:
-
Knee Exam:
-
Patellar Malalignment:
- Exam:
- hemarthrosis:
- ligamentous laxity:
- persons at risk for patellar instability may exhibit generalized ligamentous laxity & poorly developed vastus medialis;
- if hyperlaxity is present, consider
collagen disorder
- patellar position:
- when these patients are sitting or standing erect in a relaxed position patellae often faces laterally (owls eye patella);
- "J sign" - refers to lateral patellar deviation during terminal knee extension;
- quadriceps contracture:
- will cause a reverse "J" sign w/ habitual dislocation of the patella in flexion;
- patellar displacement: (Sage sign)
- the patella can normally be manually displaces both medially and laterally between 25% and 50% of width of the patella;
- greater movement indicates loose patellar restraints, a finding frequently seen in adolescent females;
- w/ pt sitting & knees flexed to 90 deg, lateral position patella
sometimes can be seen;
- patellar compression test:
- this test attempts to correlate anterior knee pain w/ articular degeneration;
- the surgeon compresses the patella down into the trochlear groove as the patient flexes and extends the knee;
- apprehension test:
- examiner holds the relaxed knee in 20 to 30 deg of flexion, & patella is manually subluxed laterally;
- Q angle:
- this is best measured both w/ the knee in extension as well as flexion;
- the Q angle may not be accurrate in extension, since a laterally dislocated patella may give the false impression that the Q angle is normal;
- in flexion, this is not a problem since the patella is well seated in the trochlear groove;
- patellar tilt test:
- w/ knee in 20 deg of flexion, the examiners thumb attempts to flip the lateral edge of the patella upwards;
- a patient w/ an excessively tight lateral retinaculum, will have almost no upward movement as compared to the opposite side;
- normally the patella can be tilted upwards above the horizontal;
- medial patellofemoral ligament
- look for tenderness at the femoral origin of the MPFL (as well as tenderness from its patellar origin);
- a lateral gluide greater than 75% of the patellar width is abnormal;
