Session V - Pelvis

Fri., 10/19/07 Pelvis, Paper #25, 11:16 am OTA-2007

Single-Leg Stance Views for the Diagnosis of Pelvic Instability

Paul Tornetta III, MD1 (e-Smith+Nephew);
David Templeman, MD2 (e-Zimmer); Jodi Siegel, MD1 (n);
1Boston Medical Center, Boston, Massachusetts, USA;
2Hennepin County Medical Center, Minneapolis, Minnesota, USA

Introduction: Patients who present with pelvic pain after injury may have underlying instability. This has been most commonly described after childbirth, but also can represent missed injury or stress fractures in the osteoporotic elderly. The diagnosis of instability is difficult. Static supine radiographs and CT scans may not demonstrate displacement. The purpose of this study is to report the effectiveness of single-leg stance views used in prospective series of patients presenting with pelvic pain and a history suggestive of pelvic instability.

Methods: 38 consecutive patients (25 female, 13 male; aged 18-78 years) presenting with pelvic pain and a history suggesting instability were evaluated with a standard series of radiographs in an attempt to define pelvic instability. 31 patients complained of primarily anterior pain, but 8 also complained of posterior pain. All but one patient was seen by at least one other orthopaedic surgeon. Prior history included motor vehicle accident (13), childbirth (8), fall (5), osteopenia (3), and other (9). The time from injury to evaluation ranged greatly, from 6 weeks to 27 years after injury or onset of symptoms, averaging 41 months. The average visual analog scale (VAS) pain score was 6.9 (range, 1-10). Each patient was evaluated with a supine anteroposterior (AP)/inlet/outlet, a standing AP, and bilateral single-leg stance views of the pelvis. The maximal change in the alignment of the pelvis on one single-leg stance view to the other was measured in centimeters. A positive test was defined as >0.5 cm of change in alignment between the views, as normal values are below 0.3 cm.

Results: Of the 38 patients, 27 demonstrated instability averaging 1.6 cm (range, 0.5-5 cm). This displacement was always seen as a difference in the heights of the symphyseal bod­ies. In only two cases was any posterior displacement visible; both were slightly widened sacroiliac joints. The single-leg stance views demonstrated instability not seen on the static supine films. The other 11 patients (29%) showed no (<0.5 cm) change in alignment. Their average VAS was 6.4, which was not different than the group as a whole.

Discussion and Conclusion: The use of single-leg stance pelvic radiographs is a more sensitive test for pelvic instability than the standard three views of the pelvis taken supine, or a standing AP pelvis. In patients presenting with pelvic pain and a history suggestive of instability, we were able to diagnose instability in 27 of 38 patients (71%) using single-leg stance views. Treatment algorithms for this problem are not fully established, but the initial diagnosis of instability is greatly aided by this radiographic series. All but one of the patients was seen by other orthopaedic surgeons and no diagnosis was made. We strongly suggest that single-leg stance views be obtained in patients with no obvious source for their pelvic pain to evaluate for potential pelvic instability. Finally, the VAS for pain was not different in the group with and without instability, thereby not helping with the diagnosis.

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.