Small N. Complications in arthroscopy: The knee and other joints. Arthroscopy 1986;4:253‑258.
Figure 8.1. Extent of passive lateral (A) and medial (B) displacement of the patella that is possible with the knee in full extension and the quadriceps relaxed. This represents the play of the patella.
Figure 8.2. If a patella tilts chronically to the lateral side, there will be adaptive retinacular shortening. With knee flexion, then, it is likely that abnormal strain will occur in this retinaculum.
Figure 8.3. Patellar map.
Figure 8.4. Axial view showing "false subluxation" due to cartilage loss.
Figure 8.5. The lateral radiographic (posterior condyles superimposed) will reveal tilt if the central ridge and lateral facet overlie each other such that normal alignment (central ridge posterior to the lateral facet) is lost (see Chapter 4).
Figure 8.6. Axial view arthrography showing lateral patellofemoral cartilage damage and narrowing (arrows). With the advent of magnetic resonance imaging, however, patellofemoral arthrography is rarely indicated.
Figure 8.7. These computerized tomographic images show how the trochlear image can vary substantially, depending on how the tomographic slice is taken. The posterior condyles provide a more consistent reference plane for determining tilt.
Figure 8.8. Computerized tomography before and after lateral release or anteromedial tibial tubercle transfer demonstrates substantial reduction of abnormal patellar tilt postoperatively. Of course, this will occur only if abnormal tilt was present preoperatively! AMZ = anteromedialization; LR = lateral release. Reprinted with permission from Fulkerson J, Schutzer S, Ramsby G, Bernstein R. Computerized tomography of the patellofemoral joint before and after lateral release or realignment. Arthroscopy 1987;3(1):19‑24.
Figure 8.9. Subchondral plate of the lateral side is markedly thickened. Relative medial compartment porosis is also evident.
Figure 8.10. Trabeculae of the patellae are seen to be oriented perpendicular to the lateral facet rather than perpendicular to the equator of the patella.
Figure 8.12. A, Peripatellar retinaculum can be demonstrated using computerized tomography. Magnetic resonance imaging (MRI) will also provide a view of the peripatellar retinaculum. B, Retinacular thickening may be visible occasionally on an axial view also. C, MRI of retinaculum. D, MRI showing patellar tendon.
Figure 8.1 3. A, Indirect radiologic signs of excessive lateral pressure. B, Indirect radiologic signs of excessive lateral ligamentous tension.
Figure 8.14. The clinician should be able to elevate the lateral facet 15 degrees or more from the horizontal plane in a normal knee. Reprinted with permission from Kolowich P, Paulos L, Rosenberg T, Farnsworth S. Lateral release of the patella: Indications and contraindications. Am J Sports Med 1990; 18(4): 359‑365.
Figure 8.15. This patient with excessive lateral pressure syndrome has the knee in full extension after retinaculum section; there is a spontaneous separation of 1.5 cm.
Figure 8.16. The patellar tilt angle in this patient is 4 degrees with the knee flexed 20 degrees. If there is minimal articular cartilage damage and patellofemoral pain that will not respond to a full nonoperative course of treatment, lateral release should be very helpful.
Figure 8.17. Axial view of both knees with (A, B) and without (C, D) contrast material compared with operative findings (E, F) (Patient 1).
Figure 8.18. Softening localized to area noted by the instrument (arrow marks lateral patellar margin).