chapter 4:imaging the patellofemoral joint
PRACTICAL ALGORITHM FOR IMAGING THE PATELLOFEMORAL JOINT
In the initial evaluation of patients with patellofemoral pain, one should obtain a standard AP; a precise standing lateral (posterior condyles superimposed), preferably weightbearing at 0 degrees and 30 degrees of knee flexion; and axial radiographs of the patellofemoral joints ( at 30 and/or 45 degrees knee flexion)). The majority of patients will require nothing more. Even when surgery becomes necessary, detailed physical examination and precise radiography may provide all that is needed in most patients.
When diagnosis and treatment become more difficult, tomographic imaging will give considerable insight into the intricacies of patellofemoral function. In particular, tomography centered on the midpatella and obtained at 0, 15, 30, 45, and 60 degrees of knee flexion will determine if there is significant subluxation or tilt of the patella. CT and MRI may be very helpful in uncovering suspected interosseous, subchondral, and peripatellar lesions.
Of the other available studies, radionuclide scanning may be helpful in selected patients when there is concern about the presence, location, or severity of patella arthrosis. The radionuclide scan may be most helpful when other studies are normal or if there is a history of anterior knee trauma and chronic patellofemoral pain. This is particularly true when the clinician wishes to establish objective findings in cases that involve compensation or litigation.
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