Augmented anterior capsular plication for type II atraumatic anterior sternoclavicular joint instability refractory to nonoperative treatment based on structural anatomic MRI findings.

Abstract

Atraumatic anterior sternoclavicular joint (SCJ) instability is attributable to a component of capsular laxity (type II) and muscle sequencing (type III). The majority of patients can be successfully treated by a specialist physiotherapy protocol. However, a small number of patients, despite adequate treatment, remain symptomatic because of a residual type II capsular laxity component. We have undertaken an augmented anterior capsular plication (ACP) procedure for patients with residual type II atraumatic SCJ instability, confirmed by MRI, refractory to adequate nonoperative treatment. Between 2015 and 2021, all patients who underwent an ACP for atraumatic SCJ instability with no evidence of a ligamentous capsular injury on MRI scan and were refractory to adequate nonoperative treatment were reviewed. Exclusion criteria were patients who had not undergone adequate nonoperative treatment, with a ligamentous injury on MRI scan or had undergone previous surgery. The procedure was a modification of a previously described augmented capsular repair for traumatic anterior SCJ instability. It consisted of a suture plication of the anterior capsule protected by an InternalBrace (Arthrex) between the medial clavicle and sternum. Patient-reported outcomes were assessed at 6 months, 12 months, and at final follow-up by the following scores: Rockwood SCJ, Oxford Shoulder Instability Score (OSIS), and Single Assessment Numeric Evaluation (SANE). Optional questions were asked about the patients' preoperative and postoperative participation in extracurricular activities and sport. Survivorship was defined as no clinical failure, such as instability or recurrent dislocation, and no revision surgery. A total of 13 patients who underwent an ACP and were available at final follow-up were included. The mean age at surgery was 20.5 years (16-25) and the mean follow-up was 46.5 months (25-75). At final follow-up, the mean score on the Quick Disabilities of the Arm, Shoulder and Hand had dropped from 32.2 (22.7-40.9) to 0.9 (4.5-0), the mean Rockwood score had risen from 7.5 (6-9) to 15, and the mean OSIS score had risen from 24.8 (18-31) to 47.5 (46-48). These all reached statistical significance. The mean SANE score at final follow-up was 95.5 (89-100). With regard to return to sport and extracurricular activities, all of the patients considered their SCJ to be either "normal" (11 patients) or to have "minor difficulties." The repair and construct survivorship was 100%. Undertaking an augmented capsular plication on patients with symptomatic atraumatic SCJ instability confirmed by MRI imaging that have failed appropriate nonoperative treatment provides a satisfactory result with regard to clinical outcomes and joint stability.