Paper 88: The Natural History of Anterior Shoulder Instability in Patients Over the Age of 50: A Population Based Study

OBJECTIVES: Anterior shoulder instability (ASI) is a well-studied topic in young patients, however there is a dearth of knowledge about older patients with this pathology. The goals of this study were to describe patient demographics, injury characteristics and outcomes in patients >50 years old with anterior shoulder instability along with historical trends in diagnosis and treatment. METHODS: An established geographic database was used to identify 179 patients who experienced new onset anterior shoulder instability after the age 50 between 1994-2016. Mean age was 59.7 years, mean BMI was 31.3 and 54.2% were female. The dominant arm was involved in 62.2% of instability events. 26.8% of our study population were laborers and 50% reported current or former smoking habits. The primary etiology for ASI involved trauma in 96.6% of cases. Comparative analysis was performed to identify differences between age groups. Mean follow up time was 11 years. RESULTS: The overall incidence of ASI in our study population was 28.8/100,000 person years with the highest incidence in the age cohort 60-64 at 38.9/100,000 person years. At initial presentation, 73% of all patients were found to have a lesion apparent on either XR or MRI. Rotator cuff tears were found in 92.4% of all patients undergoing MRIs. 26.2% ultimately progressed to surgery at a mean time of 1.57 years after injury. 53% of all surgical procedures involved a rotator cuff repair whereas only 25% were performed for instability. In terms of historical trends, the one-year rate of obtaining an MRI after an ASI event has increased from 10% in the late 1990s to 46% in 2015-16. Similarly, the one-year rate of performing surgery has increased from 5.1% to 47% from 1994-1999 to 2015-2016. CONCLUSIONS: In our cohort, patients over the age of 50 with ASI were found to often have concomitant pathology on imaging, however only ¼ of all patients required surgery. Although the rate of ASI has stayed relatively stable over the last 20 years, the rate of obtaining an MRI and of surgical management has increased.