Predicting reduction loss risk after acromioclavicular joint dislocation treated with the endobutton device

The objective of this study was to evaluate risk factors and clinical outcomes in patients with reduction loss after acromioclavicular joint dislocation treated with the Endobutton device and to develop a nomogram prediction model.

We conducted a retrospective examination of the medical records of 250 patients who had undergone ligament reconstruction using the Endobutton device. Univariate and multivariate logistic regression analyses were utilized to identify the risk factors. Subsequently, a nomogram model was constructed to forecast the probability of reduction loss. The model's discrimination and calibration were assessed using a calibration plot, receiver operating characteristic, and decision plot. To evaluate the clinical outcomes of patients experiencing reduction loss, both the Visual Analogue Scale (VAS) score and Constant score were assessed both preoperatively and at the final follow-up.

Reduction loss occurred in 25.6% (64/250) of enrolled patients during the study period. In the multivariate logistic regression analysis, independent risk factors for postoperative reduction loss were identified, including the conoid tunnel ratio (P = 0.002), trapezoid tunnel ratio (P = 0.009), coracoid button position (P < 0.001), additional pin fixation (P < 0.001), and weight-bearing time (P < 0.001). The contour map demonstrated a predictive accuracy of 0.896 in assessing the risk of reduction loss. Patients with displacement exceeding 100% of the thickness of the distal clavicle exhibited significantly worse results at the final follow-up in terms of the VAS score (P < 0.001), Constant score (P < 0.001), and subjective outcomes (P < 0.001).

Patients with displacement greater than 100% of the thickness of the distal clavicle had poorer postoperative clinical outcomes. We found a correlation between reduction loss and tunnel malposition, no additional pin fixation and premature weight-bearing of the affected limb (< 5 weeks). Our nomogram helped to identify high-risk patients and provide them with close follow-up and even surgical intervention to reduce the rate of reduction loss. It also provided us with guidance on surgical treatment for such injuries in the future.