OTA 2008 Posters

Scientific Poster #115 Upper Extremity OTA-2008

Using the Fulcrum Axis Improves the Significance of True Anteriorposterior Radiographs: A Prospective Study

Volker Braunstein, MD1,2 (n); Chlodwig Kirchhoff, MD1 (n); Christoph M. Sprecher2 (n);
Ben Ockert, MD1 (n); Markus Korner, MD3 (n); Wolf Mutscher, MD1 (n);
Ernst Wiedemann, MD4 (n); Peter Biberthaler, MD1 (n);
1Department of Traumatology and Orthopedic Surgery, Ludwig Maximilians University, Muenchen, Germany;
2AO Research Institute-AO Foundation, Davos, Switzerland;
3Department of Clinical Radiology, Ludwig Maximilians University, Muenchen, Germany;
4OCM Clinic, Muenchen, Germany

Purpose: For accurate evaluation of true anteroposterior (AP) radiographs, the joint space should be visible and the glenoid area as small as possible. So far, for true AP radiographs, the patient is positioned by turning the body about 45° toward the film. This often results in an overlapping of the humeral head and the glenoid (low quality). We recently demonstrated in an anatomic study that the axis between the anterior tip of the coracoid and the posterolateral acromion angle (fulcrum axis) is approximately parallel to the glenoid joint plane. Hence, the positioning of patients according to the fulcrum axis might allow for improved quality of true AP shoulder radiographs. Therefore, the aim of this prospective study was to compare the quality of true AP radiographs obtained either by conventional or by our new technique.

Methods: 200 patients requiring shoulder radiographs were enrolled. In group I, 100 consecutive true AP images were obtained using conventional positioning of the patients, whereas in group II 100 consecutive patients were positioned using the fulcrum axis. For quantitative comparison of interobserver reliability, three experienced orthopaedic surgeons analyzed the amount of images with free visible joint spaces and the comparable glenoid size (CGS = ratio between glenoid height and visible glenoid area). The observers were blinded for the radiographic technique used. The analysis was repeated 8 weeks later for intraobserver reliability. In addition, the learning curves of both radiographic techniques were studied.

Results: The number of complete free visible glenoid spaces was significantly higher using the fulcrum axis (31 vs 64) and the CGS increased significantly (0.08 vs 0.15). The intra- and interobserver reliability showed a high consistency for all measurements. The learning curves of both radiographic techniques approximated a horizontal line.

Conclusion: Our newly developed patient positioning technique allows for significantly improved true AP radiographic imaging of shoulder joints. The technique generates constant results from the beginning and is now ready to use for a broad application in clinical routine.

If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.

• The FDA has not cleared this drug and/or medical device for the use described in this presentation   (i.e., the drug or medical device is being discussed for an “off label” use).  ◆FDA information not available at time of printing. Δ OTA Grant.