Preoperative patient factors that predict achieving the minimal clinically important difference following arthroscopic treatment of snapping scapula syndrome.

BACKGROUND:The aim of this study was to define the minimal clinically important difference (MCID) values for patient-reported outcomes (PROs) after arthroscopic treatment of snapping scapula syndrome (SSS) using a distribution-based method, and to identify demographic, clinical, and intraoperative factors significantly associated with the achievement of MCID. It was hypothesized that subjective satisfaction scores after the procedure would be strongly associated with the achievement of MCID thresholds for the PROs and that pain, preoperative response to injection, and a scapulectomy in addition to bursal resection would be predictive of clinically relevant improvement. METHODS:Patients who underwent arthroscopic treatment of SSS between October 2005 and September 2020 with a minimum of 2-year short-term postoperative follow-up were enrolled in this retrospective single-center study. The MCID was calculated using a distribution-based approach for the following PROs: 12-Item Short Form Health Survey (SF-12), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), Quick Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH), Single Assessment Numeric Evaluation (SANE), and visual analog scale (VAS) pain "today" and "at worst." The association between achievement of the MCID and postoperative subjective satisfaction was investigated, and factors associated with achievement of MCID were determined using bivariate analysis. RESULTS:Of a total of 190 patients assessed for eligibility, 77 patients (38.1 ± 14.3 years; 36 females) were included. Within the study population, statistically significant improvements in postoperative SF-12 physical component summary (PCS) (P < .001) and mental component summary (MCS) (P < 0.034), ASES (P < .001), QuickDASH (P < .001), SANE (P < .001), and VAS pain (P < .001) scores were observed at the minimum 2-year follow-up. The calculated MCID threshold values based on the study population were 5.0 for SF-12 PCS, 5.8 for SF-12 MCS, 11.3 for ASES, -10.5 for QuickDASH, 14.7 for SANE, 1.5 for VAS pain, and 1.7 for VAS pain at worst. Reaching the MCID was strongly associated with postoperative satisfaction (rated on a scale of 1-10). Across the PROs, younger age, favorable preoperative response to injection, partial scapuloplasty or scapulectomy, no prior surgery, and pain and function at baseline were significantly associated with attaining MCID. CONCLUSIONS:Patients who underwent arthroscopic treatment for SSS experienced clinically significant improvements in functional scores, pain, and quality of life. This study demonstrated predictive roles for certain patient-specific factors and diagnostic variables for achieving MCID in PROs, which may help surgeons preoperatively assess the probability of success and manage patient expectations.