I like to examine the patient sitting with the knees bent over edge of the exam table. This allows an easy inspection of alignment, range of motion and how easy it is accomplished, and stability testing of the ligaments and patella with the patient in a relaxed position. This position also allows easy evaluation of swelling, localization of pain, direct comparison of both knees and the differences between them.
I always start with the normal or less symptomatic knee to get an idea of what is normal for the patient. I believe that exams done with the patient lying down are far less reliable for patellar problems.
The important knee examination observations should be:
- Overall alignment, valgus (knock-knee), straight, or varus (bow-leg), including the degree of valgus
- The Q Angle in both extension and flexion, the angle created by a line along the femur and patellar tendon. It is increased with more valgus or lateral position of the tibial tubercle
- Range of motion with particular attention to how easy or difficult it is
- Patellar tracking. This should be smooth and easy but may be painful or jerky.
- Patellar position in complete extension. If there is a significant Q Angle and patella Alta, you may see the patella move laterally off the femoral trochlea as the knee straightens. This is called the J Sign and is commonly associated with instabilities.
- Patellar crepitus, grinding or grating with range of motion. This indicates breakdown of the articular cartilage surface of the patella or femoral trochlea.
- Pain localization by direct pressure (palpation) to each significant area of the knee. Patellar pain is usually greatest at the inferior medial corner of the patella. This area is the insertion point of the medial patello-tibial ligament which is under tension when the patella is not centered and under pressure.
- Patellar mobility with the knee in extension and flexion. Mobility should be assessed to both lateral and medial sides. Most instability is to the lateral side but medial side laxity can be present with or without previous treatment.
- Patellar glide. The patella should slide evenly across the knee to the lateral side without rolling up on the lateral side. If the patella rolls up as it slides, this is called lateral float. This occurs because the patella rotates upward and outward on an abnormal axis rather than gliding across the femur. It is a major problem after lateral release and may occur in very lax knees without surgery. This indicates significant lateral side laxity that will need to be addressed if surgery is undertaken
- Lateral patellar centering test. This is an examination technique I have learned with experience. The test manually centers the patella in the femoral groove. It is done with the knee in some flexion over the edge of the exam table with the patient’s leg on my knee while I am sitting to the side. Pressure with my thumbs to the lateral patella moves the patella medially to allow it to find the center of the trochlea. This relieves pressure on the patella and takes tension off the medial patello-tibial ligament. If the quadriceps muscle is relaxed, this position will almost always immediately relieve pain and allow complete extension without pain. Often patients have already learned to do the same thing to relieve pain! The patient immediately understands what is required to obtain pain relief, that is the patella needs to remain in this position. Any surgical procedure needs to permanently reproduce this position. If the lateral retinaculum is extremely tight and will not allow the patella to center, the test may not be valid. Otherwise, I believe this test provides the most accurate and useful physical examination finding available for patellar problems.
- Lateral patellar pressure. If there is significant lateral side laxity producing lateral float, holding the patella down into the trochlea on the lateral side of the patella, will also eliminate pain. This is done in the same position as the lateral centering test