Background A sternoclavicular joint (SCJ) dislocation is an uncommon injury that accounts for 2% to 3% of all shoulder girdle injuries. Typically, acute SCJ dislocations are traumatic and classified as either anterior or posterior according to the direction of medial clavicular displacement. Anterior and anterosuperior dislocations are considerably more common than posterior dislocations because of the ligamentous and bony structures about the SCJ that restrict posterior and inferior translation of the medial clavicle. Most anterior SCJ dislocations are managed nonsurgically, with successful clinical outcomes. Surgical treatment is indicated in patients with a chronic and painful SCJ dislocation and healthy, active patients with an irreducible and symptomatic SCJ dislocation. Although many surgical techniques have been described for stabilization of the SCJ, no one technique is superior over another. In a broad search of the literature, we did not find any reports of a patient with an irreducible and symptomatic anteroinferior SCJ dislocation. Therefore, this video discusses the unique case presentation of a 52-year-old man with a painful, locked anteroinferior SCJ dislocation that was managed via open reduction and allograft ligament reconstruction after failed nonsurgical management. Purpose This video reviews SCJ dislocations and discusses uncommon symptoms and recommended treatment options for the management of a unique type of anteroinferior SCJ dislocation. Methods An overview of the anatomy of, mechanism of injury of, complications associated with, and management of SCJ dislocations is provided. The case presentation of a 52-year-old man with a locked and painful anteroinferior SCJ dislocation who had unusual symptoms of prominent swelling and pain in the SCJ region, acromioclavicular joint pain, and muscular spasms on the right side of the neck and trapezius muscle is discussed. A surgical technique for open reduction and internal fixation (loop-under-and-tie-over technique) with the use of a semitendinosus allograft is described. Results Excellent reduction and joint stability were achieved intraoperatively, and no complications were reported. The patient was advanced through a standardized rehabilitation protocol 6 weeks postoperatively. The patient reported considerable improvement in chest symmetry and shoulder appearance within the first few weeks postoperatively. The amount of acromioclavicular joint subluxation observed preoperatively was not evident postoperatively. The patient’s neck and trapezius spasms were no longer present, and the patient regained shoulder range of motion comparable with that of the contralateral shoulder. At last follow-up, which occurred approximately 1 year postoperatively, the patient was very satisfied with the surgery, had a subjective shoulder value of 95%, and stated that he would undergo the procedure again. Conclusion Most SCJ dislocations are anterior or anterosuperior and are successfully managed nonsurgically. This video presents a new and unique anteroinferior SCJ dislocation, which may result in unusual complications affecting the function of other joints and muscles surrounding the shoulder girdle. Surgical treatment is indicated for patients with this new and unique dislocation pattern.