Surgical stabilization of chronic traumatic anterior sternoclavicular joint instability based on magnetic resonance imaging diagnosis and structural anatomic magnetic resonance imaging findings.

Abstract

Chronic traumatic anterior sternoclavicular joint (SCJ) instability is rare. The standard imaging modality used for investigation is a computed tomography scan. However, the SCJ is usually reduced and, as a computed tomography provides minimal information regarding the soft-tissue structures, the diagnosis, treatment, and decision to operate is generally based on the clinical history and examination. We have used magnetic resonance imaging (MRI) scans to diagnose and identify the structural soft-tissue damage in patients with chronic anterior SCJ instability. The decision to operate and the specific procedure undertaken has then largely been based on these findings. Between 2008 and 2022 all patients that underwent a stabilization procedure for chronic anterior SCJ instability diagnosed by MRI were reviewed. Exclusion criteria included patients with an acute injury, where the joint remained dislocated or without an MRI scan. Patients with repairable anterior capsular tissue underwent an augmented capsular repair (ACR), with irreparable tissue a vertical figure-of-eight (VFE) hamstring tendon reconstruction and with posterior involvement a horizontal figure-of-eight (HFE) reconstruction. Patient reported outcomes were assessed by the following scores: Rockwood SCJ, Oxford Shoulder Instability Score, and Single Assessment Numeric Evaluation. Survivorship was defined as no clinical failure, such as instability or recurrent dislocation, and no revision surgery. A total of 51 patients who underwent surgery and were available at final follow-up were included. The mean age at surgery of 26.2 years (15-39) and mean follow-up of 84.7 months (36-188). The preoperative MRI scan suggested 21 patients would require an ACR (19 underwent an ACR and 2 a VFE), 23 required a VFE (5 underwent an ACR, 17 a VFE, and 1 an HFE) and 7 required an HFE. At final follow-up the mean Rockwood score had risen from 7.8 (6-11) to 14.9 (14-15 SD 0.36), the Disabilities of the Arm, Shoulder and Hand score had dropped from 31.2 (40.9-19.8) to 0.8 (0-4.5) and the mean Oxford Shoulder Instability Score score had risen from 25.8 (18-35) to 47.4 (46-48) for the whole cohort. These all reached statistical significance. The repair/construct survivorship was 98%. MRI is able to reliably diagnose and is a good predictor (positive predictive value 84.3%, negative predictive value 97.7%) of the structural soft tissue damage associated with chronic traumatic SCJ instability. Undertaking a specific operative procedure based on these findings provides a satisfactory outcome with regards to joint stability and clinical outcomes.