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Tibial tubercle-to-trochlear groove distance: Best tool for the job?
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The surgical community has long struggled with the concept of bony malalignment in the setting of patellofemoral instability. Authors agree that a subset of patients who have recurrent instability should undergo realignment of the extensor mechanism because simple soft-tissue stabilization is doomed to failure in the setting of excessive malalignment. However, the specific definition of bony malalignment in the setting of patellofemoral instability has been somewhat elusive.
The “Q angle” was devised as a method of measuring the degree of valgus about the patellofemoral joint, but problems with low inter-rater variability were noted. These were thought to be related to positioning of the patient and the limb, contraction of the quadriceps and identification of bony landmarks during the measurement. The tibial tubercle–to trochlear groove distance, as measured on axial cross-sectional imaging of the knee, was proposed as a more reproducible adjunct to the Q angle
To read the full Patellofemoral Update blog from Jacqueling Munch, MD, Jaron Sullivan, MD, and Beth Shubin Stein, MD, click here.