The Pittsburgh Instability Tool (PIT) Score Predicts Outcomes Following Arthroscopic Anterior Shoulder Stabilization in Patients with Subcritical Bone Loss.

Purpose: To evaluate rates of recurrent anterior glenohumeral instability among patients with "on-track" HSL who underwent either arthroscopic Bankart repair (ABR) alone or arthroscopic Bankart repair with remplissage augmentation (ABR+R) and develop a risk assessment tool for recurrent anterior glenohumeral instability as well as evaluate the role of remplissage augmentation for on-track shoulders to predict outcomes following arthroscopic stabilization.

Methods: We retrospectively reviewed prospectively collected data of patients aged 14-40 years who underwent ABR or ABR+R between 2013-2021. Chart review was performed to gather patient-specific risk factors such as patient age, gender, sport-specific participation, number of preoperative dislocations, shoulder laxity, while imaging measurements were used to gather glenoid bone loss and distance-to-dislocation. Recurrent anterior glenohumeral instability was defined as recurrent dislocation and/or subjective subluxation postoperatively. Exclusion criteria included: revision procedure, less than 2-year follow-up, presence of an "off-track" Hill Sachs lesion, documented connective tissue disorder, concomitant rotator cuff tear, missing data, or presence of glenoid bone loss >20%. Multivariate hazard ratio estimates were utilized to create a risk assessment tool and correlated with patient-specific risk via post-estimation analysis.

Results: A total of 170 patients were included for analysis (ABR:116 | ABR+R:54) with an average age of 21.5 ± 6.2 years and an average follow-up of 5.1 years (2.0-9.0 years). Near-track lesions ("on-track" lesions with a distance-to-dislocation value less than 10mm), presence of hyperlaxity, younger age, 2+ preoperative recurrent instability episodes, contact sport athlete status, and increasing glenoid bone loss were independent risk factors for ABR failure based on a final multivariate model predicting postoperative failure. Furthermore, patients undergoing ABR alone had a greater risk of recurrent instability than those undergoing ABR+R. From the final multivariate model utilizing these prognostic factors, the hazard ratios were utilized to create the Pittsburgh Instability Tool (PIT) and was subsequently used to create risk-stratifying subgroups: Low-risk (0 - 3), Moderate-risk (4 - 8), High-risk (9 - 13), Extreme-risk (14+). Remplissage augmentation lowered the PIT score by 8 points. Recurrent instability rates range from 2.2% among low-risk groups to 51.3% among extreme-risk groups.

Conclusions: The current study indicates that arthroscopic Bankart repair with remplissage augmentation can lower the rate of recurrent instability in patients with high-risk "on-track" lesions. Surgeons can utilize the PIT tool to identify suitable candidates who may or may not benefit from arthroscopic Bankart repair with or without remplissage augmentation by computing PIT scores for both scenarios. However, if patient risk remains elevated with or without remplissage augmentation, these individuals may not benefit solely from arthroscopic soft-tissue stabilization. The PIT risk assessment tool is a valuable resource for surgeons in evaluating the recurrence risks associated with remplissage augmentation, thus optimizing surgical strategies for on-track lesions with less than 20% GBL.

Level of evidence: Retrospective comparative case series.; level 3.