Summary

some factors may diminish or mask clinical dynamic horizontal instability not controlled by single Tightrope.

Abstract

Background

Acromioclavicular joint is a diarthrodial joint that gets its vertical stability from vertically oriented coracoclavicular ligament and horizontal stability from horizontally oriented acromioclavicular ligament with aid of coracoclavicular ligament. With high grades of acromioclavicular joint dislocation, these ligaments are torn giving rise to superior and posterior instability. Indirect coracoclavicular fixation using single Tightrope was found to regain vertical stability and static component of horizontal stability but it could never maintain the dynamic one.
We hypothesized that not all cases of standalone single Tightrope fixation should give positive clinical cross body adduction test which indicates dynamic horizontal instability and certain other factors may alter the concept.

Patients and Methods: Retrospective study as we did clinical examination during December 2020 with detection of cross body adduction test results of patients that underwent single Tightrope application in acute acromioclavicular joint dislocation in either open or arthroscopic approach during period of January 2017 till December 2020. Records, operative details, and post-operative x-rays were reviewed to assess if there were any factors that would diminish dynamic horizontal stability of acromioclavicular joint. Body mass index BMI was also calculated per each case.

Results

Our study group consisted of twenty-seven patients categorized into group A who had arthroscopic technique and group B who had open technique augmented with trans-acromioclavicular joint fixation using two k-wires for six weeks in all group B cases. Group A had seventeen cases, three had grade III and fourteen had grade V dislocations. Group B had ten cases, four had grade III and six had grade V. Mean age of study participants in November follow up was 34.2 years. Clinical cross body adduction test gave gross positive results in fourteen patients of group A and six patients in group B. Group A patients with negative results were three, two of them had grade III and third case had BMI >30. Group B patients with negative results were four, two of them had grade III, one had BMI >30, and fourth case had grade V which was unexpected.

Conclusion

The less the Rockwood grading, the more potential to secure more horizontal stability. Open approach gives also more horizontal stability that could be explained by precise anatomical reduction of acromioclavicular joint plus the add on k-wire fixation. With increased BMX, horizontal instability is usually masked. So, some factors may diminish, or mask clinical dynamic horizontal instability not controlled by single Tightrope.

Keywords: Arthroscopic, Open Reduction, Acromioclavicular Joint Injuries, Tightrope, Cross Body Adduction Test, Dynamic Horizontal Instability.