A comprehensive analysis of the acromial morphology and etiological factors for rotator cuff tears in Fosbury flop tears: bursal-sided partial-thickness tears versus full-thickness tears

Fosbury flop tears (FFTs) are a type of rotator cuff tear characterized by the tendon flipping upon itself and adhering medially. These tears have been observed arthroscopically as either bursal-sided partial-thickness tears (BSPTTs) or full-thickness tears (FTTs), though the mechanism leading to FFTs in these tear types remains unclear. This study aimed to investigate the clinical features, acromial morphology, and treatment outcomes of FFTs, stratifying patients into BSPTT and FTT groups. We included patients with small-to-medium-sized supraspinatus tendon tears who underwent arthroscopic rotator cuff repair (ARCR). Those with BSPTTs were categorized as Group P, and those with FTTs as Group F. Variables such as age, sex, diabetes mellitus status, critical shoulder angle (CSA), lateral acromial angle (LAA), sagittal and coronal acromion morphologies, Japanese Orthopaedic Association (JOA) score, and retear rate were evaluated. Group P consisted of 13 patients, primarily younger males with traumatic tears, while Group F included 40 patients, with a higher proportion of females. There were no significant differences between the groups in CSA, LAA, JOA scores, or retear rates. Both groups had a high prevalence of double-floor type osteophytes in coronal acromial morphology. FFTs were frequently observed in both BSPTTs and FTTs, particularly in patients with double-floor osteophytes. BSPTTs with FFTs may be more common in younger patients with trauma. Overall, ARCR outcomes for FFTs were similar between BSPTTs and FTTs, suggesting similar efficacy in treatment across these tear types.