This practice set contains high-yield board review questions covering key concepts in Biology, Genetics & Bone Healing. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 321
Topic: Biology, Genetics & Bone Healing
A 65-year-old female on chronic alendronate therapy for osteoporosis complains of worsening right thigh pain for three months. Radiographs reveal focal lateral cortical thickening and an incomplete transverse radiolucent line in the subtrochanteric region. What is the most appropriate management?
Correct Answer & Explanation
. Prophylactic cephalomedullary nailing
Explanation
The patient presents with symptomatic incomplete atypical femur fracture due to long-term bisphosphonate use. Because the patient has localized pain and a visible cortical disruption (the 'dreaded black line'), prophylactic cephalomedullary nailing is indicated to prevent completion of the fracture.
Question 322
Topic: Biology, Genetics & Bone Healing
A 70-year-old female presents with an atypical subtrochanteric femur fracture while on long-term bisphosphonate therapy. After surgically stabilizing the affected limb with an intramedullary nail, what is the most critical next step in her acute orthopedic management?
Correct Answer & Explanation
. Full-length radiographs of the contralateral femur
Explanation
Atypical femur fractures associated with bisphosphonate use have a high rate of bilaterality (up to 20-30%). It is imperative to obtain full-length radiographs of the contralateral femur to evaluate for impending or incomplete atypical fractures.
Question 323
Topic: Biology, Genetics & Bone Healing
A 68-year-old female presents with acute thigh pain and inability to bear weight after a simple trip and fall. Radiographs reveal a transverse fracture of the proximal femoral diaphysis with lateral cortical thickening and medial spiking. She has been taking alendronate for 12 years. What is the primary cellular mechanism contributing to this specific fracture pattern?
Correct Answer & Explanation
. Prolonged suppression of osteoclast-mediated bone remodeling
Explanation
Long-term bisphosphonate use causes prolonged suppression of osteoclast function, severely inhibiting normal bone remodeling and microdamage repair. This leads to brittle bone and the characteristic atypical femoral fractures displaying lateral cortical beaking.
Question 324
Topic: Biology, Genetics & Bone Healing
According to Perren's strain theory, what is the maximum level of interfragmentary strain that still permits primary (osteonal) bone healing without the formation of a fracture callus?
Correct Answer & Explanation
. Less than 2%
Explanation
Perren's strain theory states that primary bone healing (via Haversian remodeling) occurs when interfragmentary strain is less than 2%. Strain between 2% and 10% promotes secondary bone healing via callus formation.
Question 325
Topic: Biology, Genetics & Bone Healing
A 32-year-old woman presents with a lytic, expansile epiphyseal lesion in the proximal tibia. Histology shows mononuclear cells interspersed with multinucleated giant cells. Which of the following targeted therapies acts by binding to RANKL for the treatment of this lesion?
Correct Answer & Explanation
. Denosumab
Explanation
Denosumab is a human monoclonal antibody that binds directly to RANKL, inhibiting osteoclast formation and function. It is highly effective in the medical management of unresectable or recurrent giant cell tumors of bone.
Question 326
Topic: Biology, Genetics & Bone Healing
A 45-year-old male sustains a severe high-energy pilon fracture. He undergoes placement of an ankle-spanning external fixator on the day of injury. When assessing the patient for definitive open reduction and internal fixation (ORIF), which of the following is the most reliable clinical indicator that the soft tissues are ready?
Correct Answer & Explanation
. Resolution of fracture blisters and presence of a positive wrinkle sign
Explanation
A positive wrinkle sign indicates resolution of significant interstitial edema and is the most reliable clinical sign that the soft tissue envelope can tolerate surgical incisions for definitive ORIF. Delaying surgery until this sign appears minimizes the risk of severe wound complications.
Question 327
Topic: Biology, Genetics & Bone Healing
A 72-year-old male with a history of chronic obstructive pulmonary disease and a recent fragility fracture of the distal radius is being evaluated for secondary fracture prevention. His DEXA scan shows a T-score of -2.8 at the lumbar spine. He is currently taking calcium and Vitamin D supplements. Which of the following pharmacological interventions would be the most appropriate initial step for this patient, considering his history of a fragility fracture and severe osteoporosis?
Correct Answer & Explanation
. C. Initiate alendronate (bisphosphonate).
Explanation
Correct Answer: CThe patient has a fragility fracture and a DEXA T-score of -2.8, which meets the criteria for osteoporosis. A fragility fracture is a sentinel event, significantly increasing the risk of subsequent fractures. The case emphasizes that antiresorptive agents, such as bisphosphonates (e.g., alendronate, zoledronic acid) or RANKL inhibitors (denosumab), are the critical initial pharmacological interventions to decrease osteoclast activity and prevent further bone degradation. Bisphosphonates are typically the first-line therapy due to their efficacy, cost-effectiveness, and long-standing evidence base.Option A (Initiate teriparatide)andOption B (Initiate romosozumab)are anabolic agents that stimulate osteoblast-mediated bone formation. While highly effective, they are generally reserved for patients with severe osteoporosis, those who fracture while on antiresorptive therapy, or those with very high fracture risk. They are typically not the first-line agents for initial management after a first fragility fracture unless there are specific contraindications to antiresorptives or a history of multiple fractures.Option D (Increase calcium and Vitamin D supplementation only)is insufficient. While calcium and Vitamin D supplementation form the baseline of all pharmacological regimens, they alone are not adequate to treat established osteoporosis with a fragility fracture. Active pharmacological intervention to either reduce bone resorption or stimulate bone formation is required.Option E (Prescribe calcitonin nasal spray)is a less potent antiresorptive agent, primarily used for pain relief in acute vertebral compression fractures and has limited efficacy in preventing future fractures compared to bisphosphonates or other agents. It is not considered a first-line treatment for osteoporosis.
Question 328
Topic: Biology, Genetics & Bone Healing
A 70-year-old male with severe osteoporosis (T-score -3.0) sustains a subtrochanteric femur fracture. He is medically optimized for surgery. The orthopedic surgeon plans for intramedullary nailing. During the procedure, the surgeon encounters difficulty achieving adequate purchase with standard cortical screws for distal locking, noting the bone feels 'crunchy' and prone to stripping. This observation is consistent with the biomechanical properties of osteoporotic bone. Which of the following statements best describes the microarchitectural changes contributing to this challenge?
Correct Answer & Explanation
. B. Expansion of Haversian canals and heightened intracortical remodeling in cortical bone.
Explanation
Correct Answer: BThe case describes that cortical bone in osteoporotic patients undergoes significant thinning, with increased porosity secondary to the expansion of Haversian canals and heightened intracortical remodeling. This geometric alteration drastically reduces the area moment of inertia, leading to diminished bending and torsional strength. This microarchitectural degradation directly contributes to the 'crunchy' feel and susceptibility to stripping during screw insertion, as the thin, porous cortices cannot withstand the torque required for adequate purchase.Option A (Increased bone mineral density leading to excessive rigidity)is incorrect. Osteoporosis is characterized by decreased bone mineral density, not increased, leading to fragility rather than excessive rigidity.Option C (Pathological conversion of rod-like trabeculae to plate-like structures in cancellous bone)is incorrect. The case states the opposite: there is a pathological conversion of plate-like trabeculae to mechanically inferior rod-like structures, leading to a critical loss of connectivity and reduced ability to resist compressive and shear loads.Option D (Increased collagen cross-linking leading to enhanced bone toughness)is incorrect. The case states that alterations in collagen cross-linking and mineral crystal size lead to increased brittleness and reduced toughness, making the bone more susceptible to comminution.Option E (Reduced porosity of cortical bone, making it denser but more brittle)is incorrect. Cortical bone in osteoporosis exhibitsincreasedporosity, not reduced, due to Haversian canal expansion, which makes it weaker and more prone to stripping, not denser.
Question 329
Topic: Biology, Genetics & Bone Healing
A 75-year-old female with known osteoporosis presents with severe, intractable back pain after a fall, diagnosed with an L1 vertebral compression fracture. She has developed progressive neurological deficits, including lower extremity weakness and bowel/bladder dysfunction. Her pain has failed to respond to four weeks of medical management and bracing. Based on the case, which of the following interventions is most indicated for this patient?
Correct Answer & Explanation
. D. Surgical decompression and stabilization.
Explanation
Correct Answer: DThe case explicitly lists 'Progressive neurological deficit' as an operative indication for vertebral compression fractures. While cement augmentation (vertebroplasty/kyphoplasty) is indicated for severe, intractable pain failing medical management, the presence of progressive neurological deficits necessitates surgical decompression and stabilization to address the spinal cord or nerve root compression. This is a critical distinction, as cement augmentation alone does not decompress neural elements.Option A (Continued non-operative management with increased analgesia and physical therapy)is inappropriate given the progressive neurological deficit and intractable pain that has failed four weeks of medical management. This patient requires more aggressive intervention.Option B (Vertebroplasty or kyphoplasty for cement augmentation)is indicated for severe, intractable pain failing medical management, but it does not address neurological deficits. Cement augmentation primarily stabilizes the vertebral body and reduces pain, but it does not decompress the spinal canal.Option C (Referral to a pain management specialist for nerve blocks)might be considered for pain management in stable fractures, but it does not address the underlying mechanical instability or the progressive neurological deficit, which requires surgical intervention.Option E (Initiation of anabolic agents for bone formation)is part of secondary fracture prevention and long-term osteoporosis management. While important, it is not an acute treatment for a symptomatic vertebral compression fracture with neurological compromise.
Question 330
Topic: Biology, Genetics & Bone Healing
A 76-year-old female with a T-score of -3.2 undergoes bridge plating for a comminuted distal tibia fracture. The surgeon elects to use far cortical locking (FCL) screws. What is the primary biomechanical advantage of this construct in osteoporotic bone?
Correct Answer & Explanation
. It provides symmetric micromotion to promote robust callus formation.
Explanation
Far cortical locking (FCL) screws allow for a controlled reduction in construct stiffness by bypassing the near cortex and engaging only the far cortex. This permits symmetric biphasic micromotion at the fracture site, which stimulates secondary bone healing via callus formation.
Question 331
Topic: Biology, Genetics & Bone Healing
A 70-year-old female presents with a highly comminuted, osteoporotic proximal tibia fracture. A standard non-locked plate relies on friction between the plate and bone for stability. In contrast, how does a locked plate construct primarily fail in osteoporotic bone?
Correct Answer & Explanation
. En masse pullout of the entire construct
Explanation
Locked plate constructs function as fixed-angle devices that do not rely on friction against the bone. In severe osteoporosis, because the screws are fixed to the plate, the entire construct tends to fail via "en masse" pullout rather than individual screw toggle.
Question 332
Topic: Biology, Genetics & Bone Healing
A 45-year-old male sustains a high-energy closed tibia pilon fracture (OTA 43-C). A spanning external fixator is placed on the day of injury. What clinical parameter strictly dictates the appropriate timing for definitive open reduction and internal fixation?
Correct Answer & Explanation
. Resolution of soft tissue edema indicated by the appearance of skin wrinkles
Explanation
Staged management of pilon fractures is standard. Definitive fixation is delayed until the soft tissue envelope has adequately recovered, reliably indicated by the resolution of edema and the return of normal skin lines (the 'wrinkle sign').
Question 333
Topic: Biology, Genetics & Bone Healing
Far cortical locking (FCL) technology is sometimes used in the plate fixation of osteoporotic tibia fractures. What is the intended biomechanical advantage of FCL screws over standard locking screws?
Correct Answer & Explanation
. They decrease construct stiffness at the near cortex, promoting parallel interfragmentary motion and symmetric callus.
Explanation
Far cortical locking screws have a smooth shaft at the near cortex and lock only into the far cortex and the plate. This reduces near-cortex construct stiffness, allowing symmetric, biphasic interfragmentary motion to stimulate robust callus formation.
Question 334
Topic: Biology, Genetics & Bone Healing
An elderly patient with severe osteoporosis sustains a distal tibia spiral fracture managed with a lateral locking plate.
If mechanical failure occurs due to poor bone quality, which mechanism is most characteristic of a fully locked construct?
Correct Answer & Explanation
. En bloc pullout of the entire fixed-angle hardware construct
Explanation
Because locking screws thread directly into the plate, the construct acts as a single fixed-angle device. In osteoporotic bone with poor purchase, the construct typically fails all at once (en bloc pullout) rather than individual screws backing out.
Question 335
Topic: Biology, Genetics & Bone Healing
A 74-year-old female presents with atraumatic anterior leg pain. She has been on oral alendronate for 12 years. Radiographs reveal focal lateral cortical thickening of the tibial diaphysis with a transverse radiolucent line. What is the most appropriate management?
Correct Answer & Explanation
. Prophylactic intramedullary nailing
Explanation
Atypical tibial fractures can occur with prolonged bisphosphonate use, presenting with lateral cortical thickening and a transverse fracture line. Prophylactic intramedullary nailing is recommended for impending fractures to prevent completion and promote healing.
Question 336
Topic: Biology, Genetics & Bone Healing
A surgeon is using a bridging locking plate construct for a comminuted tibial shaft fracture in a 70-year-old osteoporotic patient. What is the biomechanical rationale for using "far cortical locking" screws instead of standard locking screws?
Correct Answer & Explanation
. To allow parallel interfragmentary motion and promote callus formation
Explanation
Standard locking constructs can be too rigid, suppressing secondary bone healing. Far cortical locking screws engage only the far cortex, allowing controlled, parallel interfragmentary micromotion at the near cortex to stimulate robust callus formation.
Question 337
Topic: Biology, Genetics & Bone Healing
A 75-year-old male with severe osteoporosis sustains a distal tibia spiral fracture. The fibula is intact. The decision is made to manage the patient non-operatively in a cast. What is the most likely deformity to develop due to the intact fibula?
Correct Answer & Explanation
. Varus
Explanation
In the presence of a distal tibia fracture, an intact fibula acts as a strut. As the tibia settles and shortens, the intact fibula typically drives the distal tibia into varus angulation.
Question 338
Topic: Biology, Genetics & Bone Healing
Reviewing an osteoporotic tibial shaft nonunion case, a 78-year-old female on chronic bisphosphonate therapy presents 9 months after IM nailing. X-rays demonstrate a hypertrophic nonunion. What is the characteristic effect of prolonged bisphosphonate use on fracture healing?
Correct Answer & Explanation
. It delays the remodeling phase by inhibiting osteoclast activity.
Explanation
Bisphosphonates work by inhibiting osteoclast function. While they generally do not prevent clinical fracture union, they significantly delay the remodeling phase of fracture healing, which relies on osteoclastic resorption of the primary callus.
Question 339
Topic: Biology, Genetics & Bone Healing
The examiner asks about contraindications for hip resurfacing. Based on the detailed list provided by the candidate, which of the following patient profiles would be an absolute contraindication for hip resurfacing?
Correct Answer & Explanation
. A 60-year-old male with severe osteoporosis and insufficient bone stock in the femoral head.
Explanation
Correct Answer: DThe candidate lists several contraindications for resurfacing: 'These include severe osteoporosis, insufficient bone stock in the femoral head, large cysts at the femoral neck or head, a narrow femoral neck, notching of the femoral neck and severe obesity (BMI > 35 kg/m2). Other contraindications include a history of chronic renal disease, metal hypersensitivity, those with anatomical abnormalities in the acetabulum or proximal femur and certainly caution in women of childbearing age.'Option D, 'A 60-year-old male with severe osteoporosis and insufficient bone stock in the femoral head,' combines two absolute contraindications explicitly stated: 'severe osteoporosis' and 'insufficient bone stock in the femoral head.'Option A: BMI of 32 is not > 35 (severe obesity). Mild femoral head cysts are not listed as an absolute contraindication, though large cysts are.Option B: While metal hypersensitivity is a contraindication, the question asks for anabsolutecontraindication from the list. This is a strong contraindication, but D combines two distinct, severe bone-related contraindications.Option C: A narrow femoral neck is a contraindication, but this option only lists one. Option D lists two severe, bone-related contraindications.Option E: 'Caution in women of childbearing age' is mentioned, but the candidate clarifies that most surgeons believe women should not be excluded, although the examiner notes a trend to avoid in all females. It's not presented as anabsolutecontraindication in the same vein as severe osteoporosis or insufficient bone stock.
Question 340
Topic: Biology, Genetics & Bone Healing
A 68-year-old woman presents with an 18-month history of left hip pain and difficulty walking. An anteroposterior radiograph of the pelvis is obtained:
Based on the radiographic findings, which of the following is the MOST characteristic feature of Paget's disease in this image?
Correct Answer & Explanation
. C. Coarsened trabecular pattern, thickened cortex, and increased bone density in the left hemipelvis and proximal femur.
Explanation
Correct Answer: CThe radiograph demonstrates classic features of Paget's disease, including a coarsened trabecular pattern, thickened left cortex, and increased density (sclerosis) of the left hip compared with the right side. Both iliopectineal (Brim sign) and ilioischiatic lines are thickened, and there is sclerosis involving the left pelvis (ileum, ischium, and pubic rami), left femur, and lower lumbar spine. These findings are highly suspicious of Paget's disease, which is characterized by disorganized bone turnover leading to biomechanically weak, enlarged, and sclerotic bone.Option A describes features of osteoarthritis, which may coexist but are not the primary findings of Paget's disease itself. Option B describes osteoporosis, which is characterized by decreased bone density, the opposite of what is seen in the sclerotic phase of Paget's. Option D describes lytic lesions, which can be seen in the early lytic phase of Paget's (e.g., osteoporosis circumscripta in the skull or 'candle flame' sign in long bones), but the predominant features in this image are sclerotic. Multiple lytic lesions are also characteristic of other conditions like multiple myeloma or metastatic disease, which are differential diagnoses but do not match the overall pattern. Option E describes features of ankylosing spondylitis, which is unrelated to the findings in this case.
Test Yourself
Switch to an interactive, timed exam simulation to truly master this topic.
