Fluoroscopic templating technique for precision arthroscopic rim trimming.

Arthroscopic rim trimming for femoroacetabular impingement can be technically challenging to perform with precision. Intraoperative assessment of the extent of acetabular rim resection is very important. Over-resection can lead to hip instability and even iatrogenic dislocation. Under-resection may leave residual impingement. A novel imaging technique is presented that is simple, practical, and readily available. The technique involves matching the fluoroscopic C-arm image intensifier to the operative pelvis while under the desired amount of hip distraction so that a horizontal anteroposterior hip image appears on the viewing monitor. An erasable marking pen is used to draw the desired area of planned acetabular rim resection directly on the viewing monitor screen. Intermittent fluoroscopic images with the raised stationary C-arm device allow assessment of superior (lateral) and anterior rim resection. The surgeon "wipes away" the drawn template with the radiopaque metallic bur until the all-important medial template border is reached, indicating that the actual rim resection matches that intended in a controlled and precise manner.