Adhesive capsulitis after COVID-19 vaccine injection: a peculiar case treated with combined bursa distention and glenohumeral capsular hydrodilatation.

Frozen shoulder is a common and self-limiting condition affecting the soft tissues of the shoulders, characterized by severe pain, impaired range of motion (ROM) and limitation of daily activities. Its prevalence is 5% and it occurs most commonly in the fifth and sixth decades of life; women are more affected [DePalma in Clin Orthop Relat Res 466:552-560, 2008]. It can be idiopathic or associated with other conditions such as metabolic disorders, diabetes, thyroid diseases, prolonged immobilization, trauma [DePalma in Clin Orthop Relat Res 466:552-560, 2008], or complications after vaccine administration known as SIRVA (Shoulder injury related to vaccine administration). SIRVA is not caused by the vaccine itself but by inappropriate vaccination techniques [Martín Arias et al. in Vaccine 35:4870-4876, 2017]. The natural history of the frozen shoulder is a progression through three stages based on clinical and arthroscopic presentations: freezing, frozen and thawing [DePalma in Clin Orthop Relat Res 466:552-560, 2008; Do et al. in Orthop J Sport Med 9:232596712110036, 2021]. The onset is characterized by disabling pain, that worsens at night; it is induced by inflammation and hypervascularity and lasts from 10 to 36 weeks [Do et al. in Orthop J Sport Med 9:232596712110036, 2021]. The second stage is predominated by stiffness and severe reduction of ROM. This phase typically lasts from 9 to 12 months [Do et al. in Orthop J Sport Med 9:232596712110036, 2021]. Eventually, a recovery phase occurs, with a gradual recovery of the ROM that can last between 12 and 42 months. Ultrasound is an emerging diagnostic tool that contributes to differential diagnosis and treatment [Zappia et al. in Insights Imaging 7:365-371, 2016; Ricci et al. in J Ultrasound Med 39:633-635, 2020]: signs of adhesive capsulitis consist of thickening of the inferior recess of the glenohumeral joint capsule, thickening of the coracohumeral ligament and soft tissue structures in the rotator cuff interval, with hypervascularity. An unspecific sign is increased fluid in the tendon sheath of the long head of the biceps [Martín Arias et al. in Vaccine 35:4870-4876, 2017; Tandon et al. in J Ultrasound 20:227-236, 2017].