These data suggest measurement of the AAA on a plain CT scan used in current practice is biased. In patients with recurrent posterior dislocation from a sitting position, accounting for the functional variations in measurement of the position of the acetabular cup provides more relevant information regarding component positioning.

A prospective, non-randomized, comparative study, Level III.

Level of evidence 4.

Purpose The purpose of this study was to assess the clinical and radiological outcomes of an arthroscopically assisted fixation of type IIB fractures using a double button device. Methods Twenty‐one patients with a type IIB displaced fracture of the clavicle who received an arthroscopically assisted fixation using a double button device were enrolled from 2009 to 2011. Clinical assessment included the patient's demographics, cause of injury, delay before surgery, time for surgery, time before resuming work and sports, the Shoulder and Hand (QuickDASH) score, the Constant–Murley score and the visual pain analogue scale (VAS). Radiological examination consisted of anteroposterior and axillary radiographs. Results The median age of patients was 33 years (range 18–67). Mean follow‐up was 35 ± 8.9 months (range 24–51 months). The average delay before surgery was 3 days (range 1–7). At final follow‐up, the mean QuickDASH score, Constant score and VAS were respectively 3.2 ± 6 (range 0–25), 94.8 ± 9.9 (range 62–100) and 0.5 ± 1.2 (range 0–4). Seventeen (81 %) patients were able to resume work, including heavy manual labour, and to resume their sport activities as well. Postoperative complications included one transient adhesive capsulitis, a symptomatic acromioclavicular joint osteoarthritis and an implant failure with nonunion. Bony union was achieved in all other patients. Conclusion This study has demonstrated that the arthroscopic treatment using a double button device was effective at providing a satisfactory functional outcome, minimizing the risk of complications and presenting low implant failure and low nonunion rates in patients with Neer type IIB fractures of the distal clavicle. Such results lead us to consider this minimally invasive technique as a first‐choice treatment. Level of evidence IV.