1. General Principles & Basic Science MCQs

When performing a total hip arthroplasty in a patient with advanced Paget's disease of the proximal femur, the surgeon should be highly prepared for which of the following intraoperative technical challenges?

While the exact etiology of Paget's disease is debated, inclusion bodies found within the osteoclasts of Pagetic bone have ultrastructural similarities to which family of viruses?

A 68-year-old man presents with progressive anterior bowing of his tibia and an enlarging hat size. Laboratory studies show markedly elevated alkaline phosphatase with normal serum calcium and phosphorus levels. What additional laboratory finding is most specific for evaluating the primary active disease process in this patient?

Electron microscopy of abnormal bone cells in a patient with osteitis deformans often reveals intranuclear inclusion bodies. These inclusions most closely resemble the nucleocapsids of which of the following virus families?

A 74-year-old woman with a known history of polyostotic Paget's disease undergoes a bone biopsy to rule out malignancy. If the biopsy is taken from an area in the 'mixed phase' of the disease, what is the classic histologic hallmark?

A neonate is diagnosed with an autosomal recessive form of osteopetrosis. Subsequent evaluation reveals concomitant renal tubular acidosis and cerebral calcifications. A mutation in the gene encoding which of the following enzymes is most likely responsible?

A bone biopsy is performed on a patient with diffuse skeletal osteosclerosis and a history of recurrent fractures. Histologic examination reveals unresorbed islands of calcified cartilage surrounded by mature lamellar bone. What is the primary diagnosis?

A 65-year-old patient with symptomatic Paget's disease is treated with intravenous zoledronic acid. Which of the following describes the primary cellular mechanism of action of this medication?

A 12-year-old child with an autosomal dominant form of osteopetrosis complains of severe jaw pain and swelling after a dental extraction. Given the underlying bone pathology, what is the most likely complication?

The most common genetic mutation in the severe malignant infantile form of osteopetrosis is a defect in the TCIRG1 gene. This mutation directly impairs the function of which crucial osteoclast component?

In the natural history of Paget's disease, the pathologic process progresses through distinct phases. The initial phase of the disease is predominantly characterized by?

A patient with severe, untreated polyostotic Paget's disease develops worsening dyspnea on exertion, cardiomegaly, and lower extremity edema. Echocardiography will most likely reveal which of the following hemodynamic states?

Genetic testing of a patient with typical features of Trichorhinophalangeal syndrome (TRPS) confirms a mutation in the TRPS1 gene. The protein encoded by TRPS1 primarily functions as a:

Which of the following scenarios is an established, absolute indication for initiating preoperative bisphosphonate therapy in an asymptomatic patient with Paget's disease?

A 65-year-old male with an isolated Pagetic lesion in the tibia complains of constant pain and increased warmth over the anterior shin. Laboratory studies reveal a significantly elevated serum alkaline phosphatase level with normal calcium and phosphorus. Which of the following is the most appropriate first-line pharmacologic treatment for this patient?

A 15-year-old presents with recurrent fractures, cerebral calcifications, and a history of renal tubular acidosis. Radiographs reveal diffuse, uniform osteosclerosis.

This specific variant of osteopetrosis is most likely caused by a deficiency in which of the following?

A 68-year-old woman undergoes total hip arthroplasty for severe secondary osteoarthritis. During templating, the proximal femur is noted to have thickened cortices and coarse trabeculae.

If a core biopsy of the femoral head were sent for pathology, which histologic description would most accurately characterize the expected findings?

A 38-year-old female undergoes arthroscopic removal of numerous loose bodies from her shoulder joint. Pathology confirms primary synovial chondromatosis. Which of the following features most reliably differentiates primary from secondary synovial chondromatosis?

Multiple hereditary exostoses (MHE) is an autosomal dominant condition linked to mutations in the EXT1 and EXT2 genes. What is the primary function of the proteins encoded by these genes?