Computational Modeling in Orthopaedics — MCQs
Which statement accurately describes a characteristic of synovial joints?
Treatment of choice for displaced fracture neck femur in a 40 years old female
Among the following dental files made of the same steel and size 55, which one is more prone to fracture?
What is the primary reason for early stabilization of a femur shaft fracture?
What is the investigation of choice for diagnosing a stress fracture?
Following a femoral shaft fracture, your consultant asks you to provide tibia traction. Which of the following will you request from the nurse? 1. Thomas splint 2. K-wire 3. Steinmann pin 4. Denham's pin 5. Bohler's stirrup 6. Bohler Braun splint
Which of the following is a contraindication for open reduction & internal fixation (ORIF)?
What is the condition commonly known as jumper's knee?
All of the following factors affect osseointegration EXCEPT:
When Class III elastics are used, what movement will the maxillary first molars exhibit?
Computational Modeling in Orthopaedics Indian Medical PG Practice Questions and MCQs
Question 1: Which statement accurately describes a characteristic of synovial joints?
- A. Hyaline cartilage covers the articular surfaces of synovial joints. (Correct Answer)
- B. The metacarpo-phalangeal joint is a condyloid joint.
- C. Cartilage can sometimes divide the joint into two cavities.
- D. Stability is inversely proportional to mobility in synovial joints.
Explanation: ***Hyaline cartilage covers the articular surfaces of synovial joints.*** - The articular surfaces of bones within a **synovial joint** are covered by a thin layer of **hyaline cartilage**, providing a smooth, low-friction surface for movement [1]. - This **articular cartilage** absorbs shock and protects the underlying bone from wear and tear [1]. - This is a **universal structural characteristic** of all synovial joints, making it the most accurate answer. *The metacarpo-phalangeal joint is a condyloid joint.* - While this statement is factually true (MCP joints are indeed **condyloid/ellipsoid joints** allowing movement in two planes), it describes a **specific type** of synovial joint, not a general characteristic of all synovial joints. - The question asks for a characteristic that describes synovial joints as a category, not an example of one specific joint classification. - This makes it incorrect as the best answer to this question. *Cartilage can sometimes divide the joint into two cavities.* - This statement refers to an **articular disc** or **meniscus**, which is a fibrocartilaginous structure that can partially or completely divide a synovial joint cavity. - This feature is present in **some** synovial joints (like the knee or temporomandibular joint) but is **not universal**. - Since it's not a characteristic of all synovial joints, it's not the best answer. *Stability is inversely proportional to mobility in synovial joints.* - Generally, there is an **inverse relationship** between **stability** and **mobility** in joints; joints designed for great mobility (e.g., shoulder) tend to be less stable, and vice-versa (e.g., hip). - However, this describes a **functional principle** or trade-off rather than a **structural characteristic** that defines synovial joints. - While true, it's not the defining characteristic being asked for in this question.
Question 2: Treatment of choice for displaced fracture neck femur in a 40 years old female
- A. None of the options
- B. Bipolar hemiarthroplasty
- C. Multiple screw fixation (Correct Answer)
- D. THR
Explanation: ***Multiple screw fixation*** - For a **displaced femoral neck fracture** in a younger patient (40 years old), **internal fixation** with multiple screws is generally the preferred treatment to preserve the native **femoral head**. - This approach aims to achieve **anatomical reduction** and stable fixation, allowing for bone healing and a better long-term functional outcome in active individuals. *Bipolar hemiarthroplasty* - This procedure is typically reserved for older, less active patients with **displaced femoral neck fractures**, particularly those with pre-existing conditions that might limit their longevity or activity level. - While it replaces the femoral head, it does not preserve the native joint, which is a less desirable outcome in a 40-year-old. *THR* - **Total hip replacement** is usually considered for older patients, or younger patients with **pre-existing arthritis** or failed internal fixation, due to concerns about the prosthesis's longevity and potential future revisions. - In a 40-year-old, the goal is typically to preserve the native joint if possible, unless there are other complicating factors. *None of the options* - Internal fixation with multiple screws is a well-established and appropriate treatment for a displaced femoral neck fracture in a 40-year-old patient. - Therefore, one of the provided options is indeed the correct treatment choice for this specific scenario.
Question 3: Among the following dental files made of the same steel and size 55, which one is more prone to fracture?
- A. Square cross-section file
- B. Triangular reamer
- C. Headstrom file (Correct Answer)
- D. Rhomboid cross-section file
Explanation: ***Headstrom file*** - Headstrom files are manufactured by grinding a spiral groove into a tapered round wire, creating sharp cutting edges and a **deep flute**. - This design results in a **reduced core mass** compared to other file types, making it inherently weaker and more susceptible to fracture, especially under torsional stress or when used improperly. *Triangular reamer* - A triangular reamer has a **triangular cross-section** which generally provides good flexibility and fracture resistance due to its symmetrical design. - While it has cutting efficiency, its broader core mass compared to the Headstrom file makes it less prone to fracture. *Square cross-section file* - Files with a **square cross-section** possess the largest core mass among conventional designs, offering excellent resistance to fracture. - This design provides high strength but may have reduced flexibility compared to other shapes. *Rhomboid cross-section file* - A rhomboid cross-section file offers a balance between flexibility and cutting efficiency, similar to a K-file but with slightly different angles. - Its cross-sectional area is still significantly larger and more robust than the deeply fluted Headstrom file, providing greater fracture resistance.
Question 4: What is the primary reason for early stabilization of a femur shaft fracture?
- A. To prevent significant blood loss.
- B. To reduce pain and discomfort.
- C. To facilitate quicker healing.
- D. To prevent fat embolism syndrome and systemic complications (Correct Answer)
Explanation: ***To prevent fat embolism syndrome and systemic complications*** - Early stabilization of femur shaft fractures significantly **reduces the incidence of fat embolism syndrome (FES)**. Fat emboli released from the bone marrow can travel to the lungs and brain, causing severe respiratory distress and neurological deficits. - By stabilizing the fracture, the **release of fat globules is minimized**, thereby preventing FES and associated systemic complications such as acute respiratory distress syndrome (ARDS) and adult respiratory distress syndrome (ADRS). *To prevent significant blood loss.* - While femur fractures can cause significant blood loss, the primary reason for early stabilization is not solely to prevent it but to reduce complications. **Blood loss is a direct consequence**, but FES poses a greater immediate threat to life. - Furthermore, **blood loss can often be managed initially by other means**, such as fluid resuscitation and direct pressure, while FES requires prompt reduction of fracture movement. *To reduce pain and discomfort.* - Reducing pain and discomfort is an important benefit of stabilization, but it is **not the primary life-saving reason** for early intervention. Analgesics and proper splinting can also address pain. - The focus on early stabilization goes beyond symptomatic relief to actively prevent **potentially fatal systemic complications**. *To facilitate quicker healing.* - While stability is crucial for proper healing, **early stabilization primarily addresses acute, life-threatening complications** rather than long-term healing rates. Optimal healing depends on many factors, including blood supply and infection control, not solely on initial stabilization. - **Quicker healing is a secondary benefit**; the immediate priority is to prevent acute morbidity and mortality associated with the fracture.
Question 5: What is the investigation of choice for diagnosing a stress fracture?
- A. X-ray
- B. CT scan
- C. MRI (Correct Answer)
- D. Bone scan
Explanation: ***MRI*** - **Magnetic Resonance Imaging (MRI)** is the most sensitive and specific imaging modality for diagnosing **stress fractures**, especially in their early stages. - It can detect **bone marrow edema** and **periosteal reactions** indicative of stress injury before cortical changes are visible on plain radiographs. *X-ray* - **X-rays** are often the initial investigation, but they have low sensitivity for **stress fractures** in the early stages as bone changes may not be apparent for several weeks. - A positive X-ray for stress fracture typically shows a **sclerotic line** or **periosteal reaction**, but this indicates a more advanced injury. *CT scan* - **CT scans** provide excellent detail of **cortical bone** and can detect subtle fractures not seen on X-rays. - While more sensitive than X-rays, CT has **higher radiation exposure** and is generally less sensitive than MRI for early detection of **bone marrow edema** associated with stress injuries. *Bone scan* - **Bone scans** (scintigraphy) are highly sensitive for detecting increased **osteoblastic activity** associated with stress fractures. - However, they are **less specific** as various conditions can cause increased uptake, and they do not provide detailed anatomical information, making MRI superior for definitive diagnosis and staging.
Question 6: Following a femoral shaft fracture, your consultant asks you to provide tibia traction. Which of the following will you request from the nurse? 1. Thomas splint 2. K-wire 3. Steinmann pin 4. Denham's pin 5. Bohler's stirrup 6. Bohler Braun splint
- A. $1,2,3,4,5,6$
- B. $3,5,6$ (Correct Answer)
- C. $3,4,5$
- D. $1,2,4$
Explanation: ***3,5,6*** - For **tibia traction** in a femoral shaft fracture, you would need a **Steinmann pin** for skeletal traction, a **Bohler's stirrup** to apply the traction force, and a **Bohler-Braun splint** to support the limb. - The **Steinmann pin** is inserted into the proximal tibia, the **Bohler's stirrup** attaches to the pin, and the **Bohler-Braun splint** provides a fixed structure for the traction system. *1,2,3,4,5,6* - This option incorrectly includes items not specifically used for applying **tibia traction** (e.g., K-wire is for internal fixation, Thomas splint is for early femur fracture management but not specifically for tibia traction application). - While some components might be used in general fracture management, not all are directly involved in setting up tibia traction as requested. *3,4,5* - This option correctly includes the **Steinmann pin** and **Bohler's stirrup** but incorrectly replaces the **Bohler-Braun splint** with a **Denham's pin**. - A **Denham's pin** is an alternative to a Steinmann pin for skeletal traction, but a **Bohler-Braun splint** is crucial for supporting the limb in this setup, which is missing here. *1,2,4* - This option includes a **Thomas splint** (used for femur fracture support, not tibia traction application), a **K-wire** (used for internal fixation, not traction), and a **Denham's pin** (an alternative to Steinmann pin, but lacks the necessary support and traction application equipment). - These items are not suitable for setting up comprehensive **tibia traction** for a femoral shaft fracture.
Question 7: Which of the following is a contraindication for open reduction & internal fixation (ORIF)?
- A. Active infection
- B. Soft bones
- C. Soft tissue contractures around the fracture site
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Active infection** at the surgical site is a significant contraindication for ORIF due to the high risk of **osteomyelitis** and implant failure. - **Soft bones**, such as those found in patients with **osteoporosis**, may not adequately hold the internal fixation devices (screws, plates), leading to implant loosening or cutout. - **Soft tissue contractures** around the fracture site can make surgical access difficult, compromise soft tissue coverage, and increase the risk of wound complications and poor functional outcomes. *Active infection* - While a direct contraindication, it's not the *only* one for ORIF. - Performing ORIF in the presence of infection significantly increases the risk of **surgical site infection** and implant failure, potentially leading to chronic osteomyelitis. *Soft bones* - This is a significant challenge for ORIF, as the bone quality may not be sufficient to hold the hardware securely. - It increases the risk of **implant failure** and non-union, but again, it's not the sole contraindication listed. *Soft tissue contractures around the fracture site* - Severe contractures can **impede surgical exposure**, make anatomical reduction difficult, and compromise the vascularity of the tissues. - This can lead to increased rates of **wound complications** and poor healing, but it is one of several contraindications.
Question 8: What is the condition commonly known as jumper's knee?
- A. Inflammation of the patellar tendon at its insertion on the patella.
- B. Tendinopathy of the quadriceps tendon.
- C. Injury to the hamstring tendon.
- D. Patellar tendonitis due to overuse of the patellar tendon. (Correct Answer)
Explanation: ***Patellar tendonitis due to overuse of the patellar tendon.*** - **Jumper's knee** is the common term for **patellar tendonitis**, which specifically refers to inflammation of the patellar tendon. - This condition is frequently caused by **overuse**, especially in activities involving repetitive jumping and landing. *Inflammation of the patellar tendon at its insertion on the patella.* - While jumper's knee does involve inflammation of the patellar tendon, it is more commonly at its insertion on the **tibial tubercle** or specifically its origin at the **inferior pole of the patella**, not necessarily at the patella itself. - This option is less precise as it describes only one aspect of the condition without mentioning the critical role of overuse. *Tendinopathy of the quadriceps tendon.* - **Tendinopathy of the quadriceps tendon** is a distinct condition affecting the tendon above the patella, known as **quadriceps tendinopathy**. - It presents with pain proximal to the patella, differentiating it from jumper's knee, which involves the tendon distal to the patella. *Injury to the hamstring tendon.* - An **injury to the hamstring tendon** would cause pain and symptoms on the posterior aspect of the knee or thigh. - This is completely unrelated to jumper's knee, which is characterized by anterior knee pain.
Question 9: All of the following factors affect osseointegration EXCEPT:
- A. Biocompatibility of implant material.
- B. Implant design.
- C. Patient's blood type (Correct Answer)
- D. Status of the host bed.
Explanation: ***Patient's blood type*** - A patient's **blood type** (e.g., A, B, AB, O) is determined by antigens present on red blood cells and plays no direct role in the biological processes of bone healing or the integration of a dental implant with bone. - While systemic factors can influence osseointegration, blood type itself does not affect the cellular and molecular mechanisms required for direct bone-to-implant contact. *Biocompatibility of implant material* - The **biocompatibility** of the implant material (e.g., **titanium**) is crucial for osseointegration, as it must not elicit adverse reactions and must permit host bone growth on its surface. - Materials that are cytotoxic or inflammatory will prevent bone apposition and lead to fibrous encapsulation rather than direct bone contact. *Implant design* - **Implant design**, including features like **surface roughness**, thread pitch, and macro-geometry, significantly influences the initial stability and long-term success of osseointegration. - A greater surface area and appropriate surface treatments can enhance bone cell attachment and differentiation, promoting faster and stronger bone integration. *Status of the host bed* - The **status of the host bone bed** refers to its quality and quantity (e.g., bone density, vascularity), which are critical for the biological processes of osseointegration. - Adequate bone volume and good bone quality provide a stable foundation and sufficient blood supply for bone regeneration around the implant.
Question 10: When Class III elastics are used, what movement will the maxillary first molars exhibit?
- A. Move distally and intrude
- B. Move mesially and extrude (Correct Answer)
- C. Move mesially and intrude
- D. Move only mesially; there will be no vertical movement
Explanation: **Explanation:** In orthodontic biomechanics, the direction of force determines the displacement of teeth. **Class III elastics** are stretched from the **mandibular anterior region** (usually the canines) to the **maxillary posterior region** (usually the first molars). **1. Why Option B is correct:** The force vector of a Class III elastic on the maxillary molar acts in a **downward and forward** direction. * **Mesial Movement:** The horizontal component of the force pulls the maxillary molar forward (mesially). * **Extrusion:** Because the elastic is attached to the lower arch (which is inferior to the maxilla), the vertical component of the force pulls the molar downward, leading to extrusion. **2. Why the other options are incorrect:** * **Option A & C:** Distal movement is characteristic of **Class II elastics**, where the force pulls the maxillary teeth backward. Intrusion would require a superiorly directed force (like a high-pull headgear), which elastics do not provide to the maxillary molars. * **Option D:** This ignores the vertical vector. In clinical practice, elastics rarely exert a purely horizontal force; the "line of action" always creates a vertical component that results in either extrusion or intrusion. **Clinical Pearls for NEET-PG:** * **Class II Elastics:** Cause **distalization and extrusion** of maxillary incisors/molars and **mesialization and extrusion** of mandibular molars. * **Side Effects:** A common side effect of Class III elastics is the steepening of the occlusal plane and a potential increase in the lower anterior facial height due to molar extrusion. * **Center of Resistance:** If the force does not pass through the center of resistance, rotation (tipping) will occur alongside translation.
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