Summary

This prospective cohort study of 95 patients with type III and V acute acromioclavicular joint dislocation found that shoulder range of motion at baseline and 6 weeks follow-up is associated with patient-reported outcome 3 months, 6 months and 1 year after the injury and with the risk of surgery.

Abstract

Background

The treatment of Rockwood type III and V acromioclavicular (AC) joint dislocations is controversial and an individualized treatment algorithm is yet to be developed. The objective of this study was to investigate the association between demographical, clinical, functional and radiographical factors at baseline and 6 weeks after Rockwood type III/V AC joint dislocation with the result after 3 months, 6 months and 1 year.

Methods

The study was a prospective cohort study with clinical, radiographical and patient-reported outcome assessment at baseline and 6 weeks, 3 months, 6 months and 1 year after acute AC joint dislocation. Inclusion criteria were patients aged 18-60 with acute AC joint dislocation and >50% superior displacement of the clavicle to the acromion. All patients were treated non-surgically with 3 months of home-based training and with the option of delayed surgical intervention. The primary outcome was the Western Ontario Shoulder Instability Index (WOSI) (0-100%, 100% being best). Secondary outcome was surgery yes/no. The following variables at baseline (b) and/or 6 weeks (6w) were investigated for association with WOSI 3 months, 6 months and 1 year after the injury and with the risk of surgery using linear or logistic regression analysis: Age (b), sex (b), workload (b), pre-injury participation in overhead sports (b), WOSI (b,6w), Shoulder Pain and Disability Index (SPADI) (0-100, 0 being best) (b,6w), range of motion (ROM) in shoulder flexion and abduction (b,6w), self-reported pain during cross-over (b,6w), presence of scapular dyskinesis (6w), horizontal and vertical instability (6w), O’Briens test (6w), cosmesis (b,6w), overriding of the clavicle to the acromion (b, 6w) and the coracoclavicular difference on radiographs (b,6w). A model to predict the need of surgical intervention was suggested and its sensitivity and specificity were determined. ClinicalTrials registration NCT03727178. This publication concerns objective 3.

Results

Ninety-five patients with Rockwood type III/V AC joint dislocation, male:female ratio 9.6:1, were included. Pre-injury participation in overhead/collision sports was a risk factor of surgery with an OR of 5 (p=0.03). At baseline, reduced ROM in both abduction and flexion was statistically significantly associated with reduced WOSI score at all time-points and risk of surgery. At 6 weeks, reduced ROM in both abduction and flexion, reduced WOSI, increased SPADI and increased pain during cross-over was statistically significantly associated with reduced WOSI score at all time-points and risk of surgery. Radiographic measurements were not associated with the result. The remaining outcomes showed inconsistent associations.
At 6 weeks follow-up, patients eventually requiring surgery could be detected with a sensitivity of 100% and a specificity of 94% based on a SPADI score of >30 points and a ROM <=140 degrees in either flexion or abduction.

Conclusion

ROM was the only factor consistently associated with both WOSI and risk of surgery. Pre-injury participation in overhead/collision sports was associated with reduced WOSI scores and increased risk of surgery. Six weeks after the injury, it was possible to detect patients in need of surgery based on ROM and SPADI with a sensitivity of 100% and a specificity of 94%.