Pronounced femur malunion after pathological bone fracture due to a simple bone cyst in the shaft of the femur, treated using Ilizarov fixation: a case report

Abstract Background Although a simple bone cyst carries the risk of pathological fractures, it rarely causes severe deformity. Here we report a case of severe femoral deformity after multiple pathological fractures due to simple bone cysts, and consider the reason for the progression of malunion despite multiple previous treatments. Finally, we propose a treatment option for malunion correction. Case presentation A 9-year, 7-month-old Japanese girl was referred to our facility with obvious deformity of her right femur, caused by multiple simple bone cyst-related pathological fractures. The deformity included bowing of approximately 90° and an internal rotation of 60° in the middle third of the femoral shaft. To correct this deformity, we excised the lesion, thus shortening the femur, then corrected the alignment and applied an Ilizarov fixator to extend the bone. At present, 3 years after surgery, the deformity has not recurred and our patient is living without any limitations in daily activities or regular exercise. Conclusions When a long bone is in a prolonged state of deformation, the deformity not only progresses as the bone grows, but the soft tissues remain unbalanced and treatment becomes increasingly difficult. To prevent increasing bone deformity and fragility, the deformity should be corrected as quickly as possible using intramedullary nailing or other fixation techniques. We believe that our shortening-distraction method is effective for the treatment of severe deformity with unbalanced soft tissues

Two cases of asymptomatic rib exostosis treated by prophylactic surgical excision

Exostosis is one of the most common benign bone lesions. It could be a solitary lesion or multiple lesions presented as part of HME. This condition often affects the metaphyseal region of long bones, including femur, tibia, humerus and ribs. Rib exostosis may cause severe complications such as pneumothorax, hemothorax, and diaphragmatic injury. We report two patients with asymptomatic rib exostosis who underwent surgical excision to prevent severe complications. The first patient was a 13-year-old male with HME. At the eight-year follow-up, the size of the exostosis at the left ninth rib was found to have increased to 5 cm in diameter and it compressed the diaphragm. Surgical excision was performed to prevent possible complications. The second patient was a 10-year-old male with HME. At the seven-year follow-up, the size of the exostosis at the right fourth rib was found to have increased to 5 cm in diameter and it protruded into the thoracic cavity. Surgical excision was performed to prevent possible complications. Both patients recovered uneventfully. The periodic evaluation of the size and shape of rib exostosis is important in HME patients, because we must judge the proper timing for surgical excision to prevent severe complications

The IRE1alpha-XBP1 pathway is essential for osteoblast differentiation through promoting transcription of Osterix

During skeletal development, osteoblasts produce large amounts of extracellular matrix proteins and must therefore increase their secretory machinery to handle the deposition. The accumulation of unfolded protein in the endoplasmic reticulum induces an adoptive mechanism called the unfolded protein response (UPR). We show that one of the most crucial UPR mediators, inositol-requiring protein 1alpha (IRE1alpha), and its target transcription factor X-box binding protein 1 (XBP1), are essential for bone morphogenic protein 2-induced osteoblast differentiation. Furthermore, we identify Osterix (Osx, a transcription factor that is indispensible for bone formation) as a target gene of XBP1. The promoter region of the Osx gene encodes two potential binding motifs for XBP1, and we show that XBP1 binds to these regions. Thus, the IRE1alpha-XBP1 pathway is involved in osteoblast differentiation through promoting Osx transcription