The Pico method is a CT-based calculation of glenoid bone loss in terms of an area (expressed in mm 2 or surface percentage). Before treatment, glenoid bone defect quantification with PICO method is required to select the best option (i.e. arthroscopy vs open surgery with bone transposition).
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Measurement
Pico method includes a comparative study of both glenoids on CT based on three parameters 1:
filter for bone
1.3 mm slice thickness
advancement of slice every 0.6 mm
images obtained are post-processed in multiplanar reformation (MPR) shifting the axes to parallel to the glenoid on three planes
in this way, en face reformats of the entire glenoid are obtained
on the en face glenoid reformat. a circumferential area centered on the inferior two-thirds with a horizontal diameter from 3 to 9 o'clock is drawn and the circumferential area is obtained
the same circumferential area is drawn on the glenoid with the deficit, and then the outline of the Bankart bone fragment or glenoid bone defect is traced, thus obtaining the area of the glenoid defect
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percentage glenoid bone loss can than be calculated
surface area normal glenoid (A)
surface area abnormal glenoid (B)
percent bone loss = (A-B)/A x 100
Interpretation
Open surgery is recommended if there is >25% glenoid bone loss, a lesion involving >30% of the humeral head, a Hill-Sachs defect involving, or bipolar bone lesions (on-track and off-track shoulder lesions) even without involvement 1.
History and etymology
"Pico” method in honor of Giovanni Pico Della Mirandola, humanist, philosopher, and academic, described by Baudi et al in 2013 1.