Background Kienböck disease is characterized by osteonecrosis of the lunate. Not all patients with radio-

We applied quantitative 3D computed tomography to 50 complete articular AO type C fractures of the distal radius and tested the null hypothesis that fracture fragments can be divided according to Melone's concept (radial styloid and volar and dorsal lunate facet fragments) and that each fragment has similar (1) displacement and (2) articular surface area. Thirty-eight fractures fit the Melone distribution of fragments. Radial styloid fragments were most displaced, and volar lunate fragments were least displaced. Volar lunate fragments had the largest articular surface area. While these findings confirm Melone's concepts, the finding that volar lunate fragments are relatively large and dorsal lunate fragments relatively small suggests that alignment of the volar lunate fragment with the radial styloid may be the key element of treatment and the dorsal lunate fragment may not routinely benefit from specific reduction and fixation.

Background Shoulder instability is associated with decreased functioning. The associated costs could be substantial and interesting to clinicians, researchers, and policy makers. This prospective observational study aims to (1) estimate productivity losses and healthcare expenses following the nonoperative treatment of shoulder instability and (2) identify patient characteristics that influence societal costs. Methods One hundred and thirty-two patients completed a questionnaire regarding production losses and healthcare utilization following consecutive episodes of shoulder instability. Productivity losses were calculated using the friction cost approach. Healthcare utilization was evaluated using standard costs. analysis of variance test was used to assess which patient characteristics are related to productivity losses and healthcare expenses. Societal costs were assessed using multilevel analyses. Bootstrapping was used to estimate statistical uncertainty. Results Mean productivity losses are €1469, €881, and €728 and mean healthcare expenses are €3759, €3267, and €2424 per patient per dislocation for the first, second, and third dislocation. Productivity losses decrease significantly after the second (mean difference €−1969, 95%CI= −3680 to −939) and third (mean difference €−2298, 95%CI= −4092 to −1288) compared to the first dislocation. Conclusions Nonoperative treatment of shoulder instability has substantial societal costs. Level of Evidence III, economic analysis.

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IV, Basic Science Study, Anatomic Study, Imaging.