Fluoroscopic Templating Technique for Precision Arthroscopic Rim Trimming

Typical supine setup for fluoroscopic templating viewed from foot of fracture table. The C-arm device is positioned over the central pelvis (red arrow), and the image intensifier x-ray detection monitor is parallel to the floor (large black arrow) and elevated well above the operative field. The table is adjusted so that the pelvis matches the image intensifier with the fluoroscopic monitor showing an AP view of the central pelvis (arrowhead) and the operative right lower extremity positioned in moderate internal rotation (small black arrow).

Fluoroscopic monitor shown in Fig 1. The central pelvis has a horizontal AP pelvis position as confirmed by the vertical alignment of the symphysis pubis (large arrow), the symmetry of the obturator foramina (large arrowheads), and the coccyx (small arrowhead) in vertical alignment with the pubic symphysis and approximately 3 cm (in this patient) from its superior border. The apex of the padded central post shadow (small arrow) towards the operative right hip and away from the midline should be noted.

Fluoroscopic image after sufficient traction is applied to the operative right lower extremity to distract that hip. (This occurs despite some initial countertraction applied to the contralateral lower extremity.) One should note the obvious lateral tilt toward the side of operative hip distraction and the alignment aid immediately before adjustment to a horizontal alignment.

View from foot of fracture table with hip distraction applied to operative right hip. The image intensifier is translated over the operative hip (large arrow), and the fluoroscopic monitor displays a horizontal AP view of the distracted hip (small arrow).

Operative side view of patient shown in Fig 4. The image intensifier x-ray detection head is positioned over the operative right hip and elevated well above the operative field (long arrow). The arthroscopic and fluoroscopic monitors are arranged adjacent to each other and ergonomically positioned for surgeon comfort with the fluoroscopic monitor confirming a horizontal AP image of the distracted hip (short arrow).

Fluoroscopic detail of distracted right hip. The template has been drawn around the area of desired rim resection with an erasable marking pen. The medial border is marked as a red line (done in Photoshop; Adobe Systems, San Jose, CA) to emphasize the desired endpoint of rim trimming in this patient. The image is a horizontal AP image of the distracted hip.

The traction device being marked with an erasable marking pen so that traction may subsequently be released during the sterile preparation and draping phase (minimizing traction time) followed by accurate reapplication of operative hip distraction. The arrow shows the horizontal AP of the distracted hip on another viewing monitor screen in the background.

Operative side view as the surgeon performs arthroscopic rim trimming of this supine patient using the fluoroscopic templating technique. The C-arm x-ray detection head is on the right, and the adjacent arthroscopic and fluoroscopic monitors are on the left. The arrow shows the fluoroscopic image of the bur at the direct superior, or 12-o'clock, position just before commencement of arthroscopic rim resection.

Fluoroscopic image prior to rim trimming with bur on the lateral margin of the region of anterolateral overcoverage near the direct superior position. The red arrow demarcates the 12-o'clock (direct superior) position while the red arrowhead demarcates the 2-o'clock (anterior) position at the level of this patient's radiographic crossover sign. The blue arrow shows a positive ischial spine sign. Both radiographic signs are indicative of acetabular retroversion.

Fluoroscopic image after superior rim trimming is completed. The bur is at the medial template border (red arrow). The blue line indicates the amount of resected superior acetabular rim at this level.

Fluoroscopic image after anterior rim trimming is completed. The bur is at the medial border (red arrow). The blue line indicates the amount of resected anterior rim at this level. The planned amount of anterolateral acetabular rim reduction has been accomplished and the crossover sign is now absent.