ABSTRACT
Background: Postoperative acromial stress fracture is a troublesome postoperative complication after reverse shoulder arthroplasty. Our study aims to utilize routinely performed preoperative computed tomography scans to identify differences in the material properties of the acromion in patients who did and did not develop a postoperative acromial stress fracture. Methods: Treatment records and computed tomography scans for 99 reverse shoulder arthroplasties were collected. Scans were calibrated using a phantom and transferred for post-processing where the acromion, full scapula, and humeral head were isolated. The final segmented model was used to assess acromial volume and volumetric bone mineral density for each region of interest. Results: There was no association between age and volumetric bone mineral density in any region of interest (all R 2 ≤ 0.048, all p > 0.082). Patients who developed an acromial stress fracture were not significantly different from those who did not in terms of age, acromial volume, or acromial volumetric bone mineral density (all p > 0.559). Patients with known osteoporosis or osteopenia had slightly lower volumetric bone mineral density, but the differences were not significant (all p ≥ 0.072). Conclusion: Postoperative acromial fractures following reverse shoulder arthroplasty cannot be predicted by computed tomography-derived volumetric bone mineral density or volume. These mechanical characteristics also do not predictably decrease with age or osteoporosis diagnosis.
ABSTRACT
BACKGROUND: Indications for reverse total shoulder arthroplasty are expanding, and postoperative acromial stress fractures are a troubling postoperative complication. The purpose of this study was to determine if differences in acromial morphometry were present between cohorts with and without this complication. METHODS: A retrospective review of 101 reverse total shoulder arthroplasty procedures met criteria for the study. A total of eight acromial measurements on preoperative computed tomography scans were performed in axial, coronal, and sagittal views. Postoperative acromial stress fractures were confirmed by computed tomography scan on six patients and classified by fracture type. Statistical analysis was performed using a Mann-Whitney U test. RESULTS: The median acromial thickness at the posterior and lateral half was significantly thinner in the fracture cohort compared to the non-fracture cohort. Fracture and non-fracture cohort measurements demonstrated a median lateral thickness of 6.8 and 8.7 mm (p = 0.010), respectively, and median posterior thickness of 7.6 and 9.5 mm (p = 0.008), respectively. There were no demographic differences between cohorts. DISCUSSION: Two acromial measurements (lateral and posterior thickness) were associated with the development of postoperative acromial stress fracture following reverse total shoulder arthroplasty. These findings suggest that a thinner acromion in the lateral and posterior half is a risk factor for an acromial stress fracture following reverse total shoulder arthroplasty.
ABSTRACT
A step-economical synthesis of clinprost is reported that concludes with 3 different transition metal-catalyzed reactions: Pd-catalyzed decarboxylation with allylic rearrangement, Rh-catalyzed diene-ene [2+2+1] reaction, and Ru-catalyzed cross-metathesis reaction. The complexity bestowed to the molecule from these reactions converts a readily accessible ester to clinprost without using protecting groups in only 9 total steps.
