Purpose: To develop a consensus on diagnosis and treatment of acromioclavicular joint instability.Methods: A consensus process following the modified Delphi technique was conducted. Panel members were selected among the European Shoulder Associates of ESSKA. Five rounds were performed between October 2018 and November 2019. The first round consisted of gathering questions which were then divided into blocks referring to imaging, classifications, surgical approach for acute and chronic cases, conservative treatment. Subsequent rounds consisted of condensation by means of an online questionnaire. Consensus was achieved when ≥ 66.7% of the participants agreed on one answer. Descriptive statistic was used to summarize the data.Results: A consensus was reached on the following topics. Imaging: a true anteroposterior or a bilateral Zanca view are sufficient for diagnosis. 93% of the panel agreed on clinical override testing during body cross test to identify horizontal instability. The Rockwood classification, as modified by the ISAKOS statement, was deemed valid. The separation line between acute and chronic cases was set at 3 weeks. The panel agreed on arthroscopically assisted anatomic reconstruction using a suspensory device (86.2%), with no need of a biological augmentation (82.8%) in acute injuries, whereas biological reconstruction of coracoclavicular and acromioclavicular ligaments with tendon graft was suggested in chronic cases. Conservative approach and postoperative care were found similarConclusion: A consensus was found on the main topics of controversy in the management of acromioclavicular joint dislocation. Each step of the diagnostic treatment algorithm was fully investigated and clarified.Level of evidence: Level V.

Background: The objective of this study was to conduct a meta-analysis and cost-effectiveness analysis of the effect of glenoid design on radiolucency, loosening, and revision after total shoulder arthroplasty. Methods: We conducted a systematic review of PubMed, MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and CINAHL with use of a search for the terms arthroplasty AND shoulder AND (peg OR keel). Data on study design and on the end points of radiolucency, loosening, and revision were extracted independently and in duplicate. Random-effect models were used to calculate the pooled risk ratio and risk difference. The risk difference was used to estimate the number needed to treat (the number of individuals who would have to receive a pegged component to avoid one loosening or revision). Results: Eight studies with a total of 1460 patients (mean age, sixty-seven years) were included. The mean study quality was 1.75 points (95% confidence interval [CI], 1.26 to 2.24) on the 3-point modified Jadad scale. There was no significant difference in the risk of any radiolucency (risk ratio, 0.42; 95% CI, 0.12 to 1.42) or in the risk of severe radiolucency (risk ratio, 0.65; 95% CI, 0.23 to 1.82) between pegged and keeled components. The pooled risk ratio for revision was 0.27 (95% CI, 0.08 to 0.88) in favor of pegged components (p = 0.028). At a cost-effectiveness threshold of $50,000 per quality-adjusted life year, pegged components can be between $2325 and $40,920 more expensive than keeled components and still be cost-effective. Conclusions: Our study produced evidence that pegged glenoid components were associated with a lower revision risk compared with keeled components. However, the difference was rather small and will therefore be most meaningful to high-volume shoulder arthroplasty centers. Because of the similarity between primary and secondary costs, pegged glenoid designs were more cost-effective than keeled glenoid designs. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.