Preoperative nerve imaging using computed tomography in patients with heterotopic ossification of the elbow

Hypothesis This study evaluated the usefulness of computed tomography (CT) imaging for preoperative planning of heterotopic ossification (HO) excision, specifically the spatial relationship between HO and radial and median nerves. Our hypotheses were that CT imaging of the elbow can be used (1) to trace the paths of the radial and median nerves, (2) to distinguish the nerves from the heterotopic bone, and (3) to precisely measure distances from the respective nerve to the most clinically relevant HO. Materials and methods Patients who had HO removed from the elbow were reviewed retrospectively. On the basis of preoperative CT scans, 22 were identified as likely having HO along the pathway of the radial or median nerve. These cases were independently evaluated by 4 observers, who answered these questions: (1) Can the location of the nerve be adequately seen on sequential images to permit tracing of its path for surgical planning? (2) Can the nerve be distinguished from the HO accurately enough to permit measurement of its distance from the bone? Each observer also measured the shortest distance between nerves and the HO. Results Overall utility of the CT images for visualizing the nerves was high. The radial nerve was more readily distinguished from the HO (21 of 22 cases) than the median nerve (17 of 22 cases). The distance measured from HO was less for the radial nerve (3 mm) than for the median nerve (9 mm). Conclusion This study demonstrates the usefulness of CT imaging to determine the paths of the radial and median nerves and their spatial relationship to HO at the elbow.