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Herein, we report a rare case of arterial cerebral air embolism (aCAE), that was probably caused by aspiration pneumonia. An 84-year-old-male presented with sudden loss of consciousness. Computed tomography (CT) of the head revealed air shadows along the sulcus of the right frontal and left posterior lobes. The abdominothoracic CT revealed aspiration pneumonia in the right upper lung with cavity formation. His clinical symptoms lessened after the administration of an antiepileptic. Because there was no prior history of any medical treatment, the patient was diagnosed with a noniatrogenic aCAE. Furthermore, in the absence of a right-to-left shunt, we determined that the air embolization was caused by the aspiration pneumonia. aCAE is a rare disease that can lead to miserable conditions. Most of causes aCAE are iatrogenic. However, a few cases of noniatrogenic aCAE have been reported. Some reports have suggested an associated between iatrogenic aCAE and raised intrathoracic pressure, which could lead to air entry into the pulmonary vein via the damaged alveolar wall. Even in noniatrogenic aCAEs, a sudden increase in intrathoracic pressure may cause airflow via the alveolar wall into the pulmonary veins, resulting in aCAE., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Most patellar dislocations occur in a lateral direction because of a summed lateral force vector and predisposing anatomic risk factors. Medial patellar instability is rare and is a well-recognized iatrogenic complication of an overly aggressive lateral retinacular release. Noniatrogenic medial patellar dislocations are rare. The management of these injuries is not well described., Purpose: To describe the experience of the International Patellofemoral Study Group with patients with noniatrogenic medial patellar dislocation., Study Design: Case series; Level of evidence, 4., Methods: Members of the International Patellofemoral Study Group (N = 64) were surveyed between October 2018 and April 2019. This group was chosen because of its wide referral base and interest in patellar instability. Specialists who had encountered a patient with medial patellar instability were sent a questionnaire inquiring about details of the case, including patient demographics, medical history, level of athletic competition, injury characteristics, and treatment. Cases were confirmed by physical examination records and, in some cases, with findings on advanced radiographic imaging., Results: The survey response rate was 73% (47/64). Three of the 47 specialists (6.4%) reported they had seen a case of noniatrogenic medial patellar dislocation, for a total of 6 cases. Four cases were described as recurrent medial dislocations in the setting of hypermobile Ehlers-Danlos syndrome; 2 were treated nonoperatively, 1 underwent lateral patellofemoral ligament reconstruction, and 1 underwent derotational osteotomies. Two medial-sided patellar dislocations in collegiate athletes were sports-related injuries that required surgical debridement but no ligamentous reconstruction. None of the patients had persistent or recurrent instability at the time of their most recent follow-up., Conclusion: Noniatrogenic medial patellar dislocations are extremely rare. This case review suggests that the treatment of first-time medial patellar instability in patients without known risk factors should follow the same principles as the treatment of lateral instability with no known risk factors, which is nonoperative management. For patients with documented risk factors and recurrence, surgery to address the risk factors may be appropriate., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: A.E.L. has received hospitality payments from Zimmer Biomet. J.F. has received research support from Active Implants, Arthrex, Episurf, Fidia Pharma, JRF Ortho, Moximed, Novartis, Organogenesis, Samumed, Vericel, and Zimmer Biomet; consulting fees from Aastrom Biosciences, Aesculap/B.Braun, Arthrex, Cartiheal, Ceterix, Cook Biotech, DePuy Synthes, Exactech, ISTO Technologies, MedShape, Moximed, Organogenesis, Osiris, Regentis, RTI Surgical, Samumed, Vericel, Zimmer Biomet, and ZKR Orthopedics; speaking fees from Aastrom Biosciences, Arthrex, Moximed, Organogenesis, Vericel, and Zimmer Biomet; and royalties from Arthrex, Biopoly, DePuy Synthes, Organogenesis, Springer, and Thieme Medical Publishers and has stock/stock options in MedShape and Ortho Regenerative Tech. S.N.P. has received education payments from CDC Medical and speaking fees from Synthes. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2021.)