AAOS Basic Science MCQs (Set 2): Bone Physiology & Biomechanics | 2002 Board Review

An otherwise healthy 75-year-old man has a painful mass in the popliteal fossa of his right knee. A lateral radiograph of the knee, a CT scan of the distal femur, and a histopathologic specimen are shown in Figures 13a through 13c. Management should consist of

What type of metastatic tumor most often has a lytic radiographic appearance?

A 6-year-old boy has leg pain. A radiograph, MRI, CT, and bone scans, and a biopsy specimen are shown in Figures 14a through 14e. What is the most likely diagnosis?

A 13-year-old girl has had right groin pain for the past 3 weeks. She denies any history of trauma. Examination of the hip reveals no palpable soft-tissue mass or lymphadenopathy, and there is full range of motion. A plain radiograph and MRI scan are shown in Figures 15a and 15b. Biopsy specimens are shown in Figures 15c and 15d. What is the most likely diagnosis?

What process is often found associated with other neoplasms?

A 14-year-old girl reports hip pain that is exacerbated by weight bearing. A radiograph and biopsy specimen are shown in Figures 16a and 16b. The best course of management should be

A 37-year-old man has left shoulder pain and weakness. Coronal T1- and axial T2-weighted MRI scans are shown in Figures 17a and 17b. The biopsy specimen is shown in Figure 17c. What is the most likely diagnosis?

Of the following factors, which is considered the most important prognostic indicator in soft-tissue sarcomas?

Radiographs of a 15-year-old girl with knee pain reveal a radiopaque lesion of the distal femoral metaphysis and epiphysis with a small associated soft-tissue mass. A biopsy specimen shows osteoid and pleomorphic cells with multiple mitotic figures. Staging studies show no other sites of disease. Treatment should consist of

What form of fixation is associated with the highest incidence of osseous union when using segmental allograft reconstruction following tumor resection?

A 51-year-old woman has had progressively increasing right knee pain for the past 6 months. She has a history of metastatic renal cell carcinoma to the lung and the skeletal system. Radiographs are seen in Figures 18a and 18b. The next step in management of the right distal femur lesion should consist of

Following resection of malignant tumors, complications related to endoprosthetic reconstruction are most common in what anatomic location?

Figures 19a and 19b show the AP and lateral radiographs of an 18-year-old man who has had knee pain for 3 months. Figure 19c shows a histopathologic photomicrograph of the biopsy specimen. Which of the following factors is most likely to affect his survival?

What anatomic site is considered at highest risk for pathologic fracture?

What clinical finding is associated with the least favorable prognosis in an adolescent patient who has been diagnosed with a high-grade osteosarcoma of the distal femur?

A 65-year-old man has a painful mass of the middle finger. A clinical photograph, lateral radiograph, coronal MRI scan, and biopsy specimen are seen in Figures 20a through 20d. What is the most likely diagnosis?

Figures 21a and 21b show the radiograph and CT scan of a 14-year-old patient with thigh pain. The next most appropriate step in management should consist of

A 14-year-old boy has a midshaft fibular lesion. Biopsy results are consistent with Ewing's sarcoma. Following induction chemotherapy, local control typically consists of

An otherwise healthy 65-year-old man reports thigh pain of insidious onset. He states that the pain is increased with weight bearing and also occurs at night. He denies any history of cancer. Radiographs are shown in Figures 22a and 22b. A bone scan shows an isolated lesion. CT scans of the chest and abdominal are negative for any other lesions. Initial management should consist of

What is the most appropriate next step in the work-up of a patient with the asymptomatic lesion shown in Figure 23?

A 63-year-woman has an elbow flexion contracture. History reveals that she underwent three previous surgeries to remove a malignant fibrous histiocytoma of the forearm. An MRI scan reveals a locally recurrent tumor at the site of the previous surgery. Which of the following is considered the most predictive factor for local recurrence?

A 19-year-old woman has a painful right knee. A radiograph, MRI scan, CT scan, and histopathologic specimen are shown in Figures 24a through 24d. What is the most likely oncologic stage of the lesion?

Calcitonin acts as an antiresorptive agent by

An 8-year-old girl has had a painless enlarging mass of insidious onset in the left thigh for the past 3 weeks. Her mother denies any history of trauma, fever, or disease. Examination reveals a nontender, mobile mass in the left medial thigh. Her gait is normal. Figures 25a through 25d show the frog-lateral radiograph, the axial and coronal T1-weighted MRI scans, and the axial T2-weighted MRI scan. Biopsy results reveal a nonrhabdomyosarcoma soft-tissue sarcoma. The most appropriate treatment should consist of

Histologically, synovial chondromatosis is characterized by

Which of the following molecules acts as a decoy receptor to inhibit osteoclast differentiation and activity in the bone remodeling cycle?

The viscoelastic nature of bone implies that its mechanical properties depend heavily on the rate of loading. When bone is subjected to a higher strain rate, it exhibits which of the following characteristics?

During the incorporation of a massive structural cortical bone allograft, the mechanical strength of the graft temporarily decreases. This process is primarily mediated by which of the following?

According to Perren's strain theory, absolute stability at a fracture site, defined as strain less than 2%, promotes which type of bone healing?

Bone morphogenetic proteins (BMPs) primarily exert their profound osteoinductive effects by initiating intracellular signaling through which of the following pathways?

In the fixation of a diaphyseal fracture using a bridge plate technique, intentionally increasing the distance between the innermost screws adjacent to the fracture gap (increasing the working length) has what biomechanical effect on the construct?

Mixing stainless steel and titanium implants within the same operative site is generally avoided due to the risk of implant degradation and failure. What is the primary mechanism of metal degradation in this specific scenario?

A 45-year-old patient with end-stage renal disease presents with metabolic bone disease (renal osteodystrophy). Which critical step of Vitamin D metabolism is most likely impaired in this patient?

Osteopetrosis is a genetic condition characterized by overly dense, disorganized, and brittle bones. What is the primary underlying cellular and molecular defect in this disease?

During bone remodeling under mechanical loading, the convex side of a bowed long bone experiences tension, while the concave side experiences compression. According to the piezoelectric effect, what is the electrical charge and corresponding cellular activity on the compressive side?

Which specific zone of mature articular cartilage contains the highest concentration of water and features collagen fibers oriented parallel to the joint surface to resist high shear stresses?

On a standard stress-strain curve for a healthy human ligament, the initial non-linear 'toe region' represents which of the following physical phenomena?

Which of the following alterations to the design of a surgical bone screw will most significantly increase its pull-out strength when inserted into cancellous bone?

A pediatric patient presents with bleeding gums, petechiae, and metaphyseal bone pain. Radiographs reveal a densely sclerotic 'white line of Frankel' at the metaphyses. The underlying defect is a failure of which biochemical process?

Aseptic loosening in total joint arthroplasty is primarily driven by a biological host response to particulate wear debris. Which cell type is the primary initial responder that engulfs these particles and releases pro-inflammatory cytokines like TNF-alpha and IL-1?

Nitrogen-containing bisphosphonates, such as alendronate, inhibit osteoclast function and induce cellular apoptosis by directly disrupting which of the following intracellular pathways?

In biomaterials testing, an S-N (Wöhler) curve is utilized to determine the endurance limit of a metallic orthopedic implant. The endurance limit specifically represents the:

Which of the following osseous structures develops primarily through the process of intramembranous ossification, bypassing a cartilaginous anlage intermediate stage?

Stress shielding around a rigid, cementless femoral stem occurs because the metallic implant is significantly stiffer than the surrounding cortical bone. Which of the following fundamental material properties best quantifies this stiffness?

Parathyroid hormone (PTH) plays a critical role in maintaining serum calcium homeostasis by acting on bone, the kidneys, and the intestines. Which of the following represents a direct physiological effect of PTH on the kidneys?

In the stress-strain curve of cortical bone, the point at which the material begins to undergo permanent deformation without a significant increase in load is known as the:

Ligaments and tendons exhibit time-dependent mechanical properties. The phenomenon where a tissue experiences a decrease in stress over time when held at a constant strain is known as:

Which of the following best describes the mechanical difference between cortical and cancellous bone?

Sclerostin is a protein that plays a key role in bone remodeling by inhibiting bone formation. Which of the following cells primarily secretes sclerostin?

Denosumab is used in the treatment of osteoporosis and giant cell tumors of bone. It acts by directly binding to and inhibiting which of the following?

Which of the following local factors is considered the most critical initiator of the fracture healing cascade immediately following injury and hematoma formation?

Demineralized bone matrix (DBM) primarily provides which of the following properties to aid in bone healing?

Mixing stainless steel and titanium implants in the same anatomical region is generally discouraged due to the risk of galvanic corrosion. Which of the following factors primarily drives this process?

In the classical pathway of vitamin D metabolism, which of the following enzymes is responsible for the conversion of 25-hydroxyvitamin D to its most active form, 1,25-dihydroxyvitamin D?

A 6-year-old child sustains a physeal injury to the distal femur, leading to asymmetric physeal arrest and subsequent angular deformity. This process of altered bone growth due to increased compressive forces is described by:

Cortical bone exhibits different mechanical properties depending on the direction of the applied load. This characteristic is known as:

In biomaterials science, the stress level below which an implant material can undergo an infinite number of loading cycles without failing is termed the:

A 10-year-old child presents with bleeding gums, petechiae, and bone pain. Radiographs reveal a Pelkan spur. The underlying pathophysiology involves a defect in the synthesis of which of the following?

The pullout strength of a cortical screw is directly proportional to which of the following parameters?

Parathyroid hormone (PTH) maintains serum calcium levels through several mechanisms. Which of the following is a direct physiologic effect of PTH?

The primary defect in Paget's disease of bone is characterized by which of the following cellular abnormalities?

Which of the following is the hallmark histological finding in osteomalacia?

When applying a compression plate to a transverse midshaft femur fracture, the plate is ideally placed on the tension side of the bone. For the human femur, the tension side is generally located on the:

Which of the following best describes the process of fretting corrosion in orthopedic implants?

The compressive stiffness of articular cartilage is primarily provided by the interaction between which two matrix components?

Which of the following cytokines is secreted by osteoblasts to directly inhibit osteoclastogenesis?

If the inner diameter of a hollow intramedullary nail is kept constant while the outer diameter is doubled, how does the torsional rigidity of the nail change?

A viscoelastic material subjected to a constant load exhibits a progressive increase in deformation over time. This phenomenon is known as:

Sclerostin, an important regulator of bone mass, primarily functions by inhibiting which of the following signaling pathways?

Which of the following bones undergoes formation primarily via intramembranous ossification?

During the incorporation of a cortical bone allograft, the process of simultaneous bone resorption and formation by osteoclasts and osteoblasts cutting cones is termed:

In the metabolism of Vitamin D, the conversion of 25-hydroxyvitamin D to its most active form, 1,25-dihydroxyvitamin D, occurs primarily in which organ?

According to the piezoelectric properties of bone, compression of a long bone results in which of the following electrical charges and cellular responses at the compressed surface?

Nitrogen-containing bisphosphonates (e.g., alendronate) inhibit bone resorption primarily by inhibiting which of the following enzymes?

Which of the following scenarios is most likely to result in galvanic corrosion?

The resistance of a rectangular plate to bending depends on its area moment of inertia. If the thickness of the plate in the plane of bending is doubled, how does its bending rigidity change?

Continuous, high-dose administration of Parathyroid Hormone (PTH) leads to which of the following net effects on bone?

Absolute stability of a fracture (e.g., rigid compression plating) leads to which type of bone healing?

Bone Morphogenetic Proteins (BMPs) transmit signals to the nucleus of osteoprogenitor cells primarily through which of the following intracellular mediators?

On a stress-strain curve, the area under the entire curve up to the point of failure represents which mechanical property of the material?

Which of the following histologic findings is characteristic of osteomalacia?

Particle-induced osteolysis after total joint arthroplasty is primarily driven by the phagocytosis of wear debris by which of the following cells?

Which type of collagen is the predominant organic component of normal mature cortical bone?

In biomechanics, the S-N curve (stress vs. number of cycles) is used to evaluate a material's susceptibility to:

Which of the following mechanical properties best describes a material whose mechanical behavior is dependent on the rate at which the load is applied?

Osteoprotegerin (OPG) functions to inhibit osteoclastogenesis by directly binding to which of the following molecular targets?

On a standard stress-strain curve for cortical bone, the slope of the curve within the linear elastic region represents which of the following mechanical properties?

Mutations in the retinoblastoma (Rb) gene are strongly associated with the subsequent development of which of the following primary bone tumors?

Nitrogen-containing bisphosphonates, such as alendronate, inhibit osteoclastic bone resorption primarily by targeting which of the following enzymes in the mevalonate pathway?

The torsional rigidity of a solid cylindrical intramedullary nail is mathematically proportional to its radius raised to which of the following powers?

According to Perren's strain theory, what is the maximum local tissue strain environment that allows for the formation of lamellar bone?

During the initial phase of acute, high-rate loading of articular cartilage, which component is primarily responsible for resisting the applied compressive force?

Highly cross-linked ultra-high molecular weight polyethylene (UHMWPE) reduces adhesive and abrasive wear in total hip arthroplasty primarily through which of the following mechanisms?

Which process accurately describes the incorporation of a massive cortical structural allograft, characterized by simultaneous osteoclastic resorption and osteoblastic bone formation that gradually replaces the dead graft?

A surgeon utilizes a stainless steel plate and secures it with titanium alloy screws. Which specific type of corrosion is most likely to occur at the plate-screw interface?

The characteristic chromosomal translocation t(11;22)(q24;q12) found in the majority of Ewing sarcoma cases results in the fusion of which two genes?

A patient with chronic severe vitamin C deficiency presents with joint effusions, gingival bleeding, and poor wound healing. The underlying pathophysiologic mechanism directly impairs which step of collagen synthesis?

Parathyroid hormone (PTH) acts directly on the kidney to increase serum calcium levels through which of the following mechanisms?

Which of the following orthopedic implant materials possesses a Young's modulus (elastic modulus) that is closest to that of human cortical bone?

In the context of the viscoelastic properties of ligaments and tendons, what is the biomechanical term for the progressive decrease in tension over time when the tissue is held at a constant length?