No Short-Term Effects of Acromioclavicular Joint Augmentation in Acute Acromioclavicular Joint Stabilization Surgery: A Randomized Controlled Clinical Trial on 70 Patients

<b>Background</b>: Optimal treatment for high-grade acromioclavicular (AC) joint dislocations is still not unanimous. Improving horizontal AC stability has been emphasized in recent years. Biomechanical studies and computer simulations have demonstrated that adequate horizontal stability could be restored with an additional AC fixation. We aim to prospectively investigate if AC augmentation leads to better clinical and radiological results. <b>Methods</b>: A total of 70 patients with a mean (± SD) age of 42 ± 11 years with acute AC joint dislocation Rockwood type IIIb and V were prospectively randomized into two equal groups. All patients underwent arthroscopically assisted stabilization using a double coracoclavicular (CC) suspensory system. Group N (No-augmentation group) had no additional fixation across the AC joint, while group T (tape-augmentation group) had additional fixation with tape. Patients were evaluated at 3, 6, and 12 months postoperatively. Primary clinical outcome measures included the Constant-Murley score and the Specific AC Score (SACS). Secondary outcome measures included the Subjective Shoulder Value (SSV), the Simple Shoulder Test (SST), the Disabilities of the Arm, Shoulder, and Hand (DASH) outcome measure, and the AC Joint Instability (ACJI) Score. Horizontal stability was radiologically measured with overlapping length (OL) and overlapping area (OA). Vertical alignment was measured with the CC distance. All radiological measurements were compared to the uninjured side and expressed in percentages as relative values. <b>Results:</b> There were no significant differences found between groups regarding the Constant score (<i>p</i> = 0.664), SACS (<i>p</i> = 0.518), or any other outcome measure at the one-year follow-up. Pain level (<i>p</i> = 0.635) and strength (<i>p</i> = 0.217) at the one-year mark also showed no significant differences. Clinical drawer testing for residual horizontal instability was non-significant (<i>p</i> = 0.061), but showed a tendency for a more stable AC joint in group T. The CC distance was smaller in group T at 6 and 12 months (<i>p</i> = 0.047 and <i>p</i> = 0.046, respectively). A two-way mixed factorial ANOVA test showed significantly lower CC differences for group T (<i>p</i> = 0.032); however, the gradual increase in CC distance was similar for both groups over time (<i>p</i> = 0.869). No significant differences were found in OL (<i>p</i> = 0.619) or OA (<i>p</i> = 0.236). <b>Conclusions:</b> The results of our study show that both CC stabilization with the double suspensory system alone and with additional AC fixation are effective surgical treatment options for acute AC joint dislocations, without any important clinical differences. CC distance similarly increased over one year in both groups but was better retained in the AC-augmented group, which showed a tendency toward a more stable fixation.