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Updated Orthopedic Review | Dr Hutaif General Orthopedi -...

Orthopedic A Review | Dr Hutaif General Orthopedics Rev -...

23 Apr 2026 21 min read 151 Views
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This interactive board review contains 100 randomly selected orthopedic surgery questions with clinical images, immediate feedback, and detailed references.

Orthopedic A Review | Dr Hutaif General Orthopedics Rev -...

Comprehensive 100-Question Exam


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Question 1

During the process of secondary fracture healing, a cartilaginous soft callus forms to bridge the fracture gap. Which type of collagen is the predominant structural component of this early soft callus phase?





Explanation

Secondary fracture healing proceeds through hematoma formation, fibrocartilaginous (soft) callus, bony (hard) callus, and remodeling. The soft callus is primarily composed of cartilage, which is rich in Type II collagen. As endochondral ossification progresses, Type X collagen is expressed by hypertrophic chondrocytes, followed by the deposition of Type I collagen as woven bone is formed.

Question 2

Which of the following is considered the earliest and most reliable clinical sign of acute compartment syndrome in an awake, alert patient?





Explanation

Pain out of proportion to the injury and pain with passive stretch of the muscles in the involved compartment are the earliest and most sensitive clinical indicators of compartment syndrome. Pulselessness, pallor, and paralysis are late signs indicating irreversible ischemic damage.

Question 3

A 70-year-old woman is started on denosumab for the treatment of severe osteoporosis. What is the specific mechanism of action of this medication?





Explanation

Denosumab is a fully human monoclonal antibody that binds directly to Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL). By binding to RANKL, it prevents RANKL from interacting with the RANK receptor on osteoclasts and their precursors, thereby inhibiting osteoclast formation, function, and survival.

Question 4

A 14-year-old boy presents with progressive knee pain and swelling over the past 2 months. A representative imaging study of the distal femur is shown below.

Assuming the radiograph demonstrates a destructive metaphyseal lesion with a 'sunburst' periosteal reaction and Codman's triangle, what is the most likely diagnosis?





Explanation

The clinical presentation of a teenager with a destructive, bone-forming metaphyseal lesion demonstrating aggressive periosteal reactions (like a sunburst pattern or Codman's triangle) is highly characteristic of conventional osteosarcoma. Giant cell tumors are typically epiphyseal, and Ewing sarcoma usually presents as a permeative diaphyseal lesion with 'onion-skin' periosteal reaction.

Question 5

While Staphylococcus aureus is the most common overall cause of acute hematogenous osteomyelitis, patients with sickle cell disease have a uniquely higher incidence of infection caused by which of the following organisms compared to the general population?





Explanation

In patients with sickle cell disease, functional asplenia and bone infarcts (which can serve as a nidus for infection) predispose them to osteomyelitis. While S. aureus is still extremely common, Salmonella species are uniquely associated with osteomyelitis in sickle cell patients and account for a significantly higher percentage of cases than in healthy individuals.

Question 6

During intraoperative ACL reconstruction tensioning, the graft is held at a constant length. Over time, the surgeon notes a gradual decrease in the force required to maintain this specific length. This viscoelastic property is known as:





Explanation

Stress relaxation is the decrease in stress (force) over time when a viscoelastic material is held at a constant strain (length). Creep is the continuous deformation (increase in length) over time when a material is subjected to a constant stress (load). Hysteresis refers to the energy lost as heat during the loading and unloading cycle.

Question 7

Achondroplasia is the most common form of short-limb dwarfism. The underlying pathophysiology involves a gain-of-function mutation in the FGFR3 gene, which primarily inhibits chondrocyte function in which zone of the physis?





Explanation

Achondroplasia is caused by a mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene. This gain-of-function mutation abnormally inhibits chondrocyte proliferation, specifically affecting the proliferative zone of the physis, leading to decreased endochondral ossification and shortened long bones.

Question 8

A 65-year-old man presents with dull, aching bone pain, increasing head size, and progressive hearing loss. A biopsy of his affected bone is shown below.

If the histology demonstrates haphazardly arranged cement lines creating a 'mosaic' pattern, what is the most likely diagnosis?





Explanation

Paget's disease of bone (osteitis deformans) is characterized by a focal increase in bone remodeling. In the late (osteosclerotic) phase, disorganized woven and lamellar bone is laid down, creating a classic 'mosaic' pattern with prominent, haphazard cement lines. Clinical features include bone pain, bowing deformities, increasing skull size, and cranial nerve impingement (e.g., hearing loss).

Question 9

A 35-year-old male presents with a deep-seated, painful soft tissue mass in his thigh. Core needle biopsy confirms Synovial Sarcoma. Which of the following chromosomal translocations is uniquely diagnostic for this tumor?





Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, which results in the SYT-SSX fusion gene. t(11;22) is seen in Ewing sarcoma; t(12;16) in myxoid liposarcoma; t(2;13) in alveolar rhabdomyosarcoma; and t(9;22) in chronic myelogenous leukemia (Philadelphia chromosome).

Question 10

Normal articular cartilage is highly specialized to resist compressive loads. Which zone of articular cartilage contains the highest water content, the lowest proteoglycan concentration, and collagen fibrils aligned parallel to the joint surface?





Explanation

The superficial (tangential) zone of articular cartilage has the highest water content (up to 80%) and the lowest concentration of proteoglycans. Its collagen fibers (primarily Type II) are aligned parallel to the articular surface to resist shear forces.

Question 11

In orthopedic reconstructive surgery, varying bone graft materials are utilized based on their biologic properties. Which of the following graft options possesses osteogenic, osteoinductive, AND osteoconductive properties?





Explanation

A cancellous autograft is the 'gold standard' because it is the only option that contains living cells (osteogenic), growth factors like BMPs (osteoinductive), and a 3D scaffold (osteoconductive). Allografts are primarily osteoconductive. DBM is osteoconductive and osteoinductive. Synthetics are solely osteoconductive, and rBMP-2 is solely osteoinductive.

Question 12

According to the mechanical principles of intramedullary fixation, the bending stiffness of a solid cylindrical titanium intramedullary nail is proportional to its radius raised to which power?





Explanation

The bending stiffness (area moment of inertia) of a solid cylinder is proportional to the radius to the fourth power (r^4). Torsional stiffness (polar moment of inertia) is also proportional to r^4. This means that even a small increase in the diameter of an intramedullary nail significantly increases its stiffness.

Question 13

A 24-year-old polytrauma patient arrives in the emergency department with a heart rate of 130 bpm, decreased pulse pressure, confusion, and a urine output of 10 mL/hr. According to the ATLS classification of hemorrhagic shock, what estimated percentage of blood volume has this patient lost (Class III shock)?





Explanation

This patient exhibits signs of Class III hemorrhagic shock (tachycardia >120, decreased blood pressure/pulse pressure, confusion, decreased urine output). Class III shock corresponds to a blood volume loss of 31-40% (approx. 1500-2000 mL in an adult). Class I is up to 15%; Class II is 15-30%; Class IV is >40%.

Question 14

Vitamin C deficiency (scurvy) results in weakened connective tissue, bone pain, and mucosal bleeding. At a cellular level, Vitamin C acts as an essential cofactor for which of the following steps in collagen synthesis?





Explanation

Vitamin C (ascorbic acid) is a crucial cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase, which add hydroxyl groups to proline and lysine residues on the preprocollagen chains. This hydroxylation is required for the subsequent stable formation of the collagen triple helix.

Question 15

A 68-year-old woman sustains a distal radius fracture after a low-energy fall. DEXA scanning reveals a T-score of -2.8 at the femoral neck. In primary osteoporosis, which of the following best describes the typical serum laboratory profile for calcium, phosphate, and alkaline phosphatase (ALP)?





Explanation

Primary osteoporosis is characterized by low bone mass and microarchitectural deterioration, but routine serum chemistries (Calcium, Phosphate, Alkaline Phosphatase) are classically within normal limits. Abnormalities in these labs should prompt investigation for secondary causes such as osteomalacia, hyperparathyroidism, or Paget's disease.

Question 16

A 10-year-old boy falls and sustains a distal radius fracture. Radiographs show a fracture line that passes transversely through the physis and exits through the metaphysis. According to the Salter-Harris classification, fractures that traverse the physis predominantly occur through which histologic zone?





Explanation

Salter-Harris fractures most commonly occur through the hypertrophic zone of the physis, specifically at the junction of the calcified and uncalcified regions. This zone is mechanically the weakest part of the growth plate because the cells are enlarged and the extracellular matrix is relatively sparse.

Question 17

Fibrous dysplasia is a benign developmental anomaly of bone characterized by replacement of normal medullary bone with fibro-osseous tissue. Which gene mutation is the underlying cause of this condition?





Explanation

Fibrous dysplasia is caused by an activating post-zygotic somatic mutation in the GNAS1 gene, which encodes the alpha subunit of a stimulatory G-protein (Gs-alpha). This leads to increased intracellular cAMP, causing abnormal differentiation of osteoblasts. EXT1 is associated with multiple hereditary exostoses; FGFR3 with achondroplasia; COMP with multiple epiphyseal dysplasia; and COL1A1 with osteogenesis imperfecta.

Question 18

Tranexamic acid (TXA) is widely used in orthopedic surgery to reduce perioperative blood loss. What is the specific mechanism of action of TXA?





Explanation

Tranexamic acid is a synthetic lysine analog that acts as an antifibrinolytic agent. It competitively binds to the lysine-binding sites on plasminogen, thereby preventing its activation to plasmin and subsequent degradation of fibrin clots.

Question 19

A 72-year-old man presents with severe back pain and is found to have diffuse osteoblastic lesions in his lumbar spine. A biopsy is consistent with metastatic prostate cancer. Which factor, secreted by the prostate tumor cells, primarily mediates this characteristic osteoblastic response?





Explanation

Metastatic prostate cancer is classically associated with osteoblastic (bone-forming) bone lesions. Prostate cancer cells secrete Endothelin-1 (ET-1), which strongly stimulates osteoblast proliferation and bone formation. In contrast, tumors like breast or lung cancer typically secrete PTHrP, leading to osteolytic lesions.

Question 20

In total joint arthroplasty, the use of modular components (such as a titanium stem with a cobalt-chromium head) can lead to a specific type of electrochemical degradation at the modular junction. What type of corrosion is driven by the contact of two dissimilar metals in an electrolytic solution (synovial fluid)?





Explanation

Galvanic corrosion occurs when two dissimilar metals with different electrochemical potentials (e.g., Titanium and Cobalt-Chromium) are placed in contact within a conductive solution (such as human extracellular fluid). The less noble metal acts as an anode and undergoes accelerated corrosion. Fretting corrosion is mechanically mediated due to micromotion between components.

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