Bilateral Tibial Proximal Fractures Caused by Secondary Osteomalacia due to Autoimmune Polyendocrine Syndrome Type 2: A Case Report

Introduction: Hypophosphatemic osteomalacia can be overlooked or confused with other musculoskeletal disorders due to the variety of associated clinical, laboratory, and radiographic findings. If osteomalacia is diagnosed early and the fractures are not displaced, they often heal with nutritional supplements, but, if they progress to displaced fractures, they may require surgical intervention. Case Report: We present a case of secondary osteomalacia due to autoimmune polyendocrine syndrome Type 2 due to this condition, the patient developed bilateral tibial proximal fractures and her varus deformity had progressed. No clear indication of the timing for surgery for adults with osteomalacia has been reported. However, medical treatment improves the symptoms of osteomalacia and it is reported that in children, appropriate level of the serum phosphate (P) should be attained and maintained for the successful bone healing after osteotomy. Therefore, we prioritized pharmacological treatment and prescribed surgery after confirming that the value of serum phosphate P had been improved to recommended levels (2.5-3.5 mg/dl). We performed high tibial osteotomy for the right side and gradual correction by an external fixation for the left tibia, because of more severe deformation, and converted to an internal fixation to shorten the treatment period. During conversion, we performed the operation with a locking plate by the minimal invasive plate osteosynthesis method (MIPO). Conclusion: We conclude that the use of different deformity correction methods, depending on the degree of deformity, and the pharmacological treatment of osteomalacia may lead to favorable results. Keywords: Osteomalacia, autoimmune polyendocrine syndrome type 2, deformity correction method.