Basic Science in Orthopaedics Practice Questions

Q: The X-ray shows plating done for a fracture. How does this fracture heal?

Primary healing. **Primary healing** - **Plating of a fracture** aims to achieve **absolute stability** at the fracture site, which facilitates primary bone healing. - In primary healing, there is **direct bone formation** across the fracture gap without the formation of a significant callus. *Secondary healing* - Secondary healing involves the formation of a **callus** (fibrous tissue, cartilage, and immature bone) to bridge the fracture gap. - This type of healing occurs in situations with **relative stability** and some micromotion at the fracture site, such as with casting or intramedullary nailing. *Tertiary healing* - **Tertiary healing** is not a recognized term in the context of fracture healing. - Bone healing typically involves either primary or secondary mechanisms depending on the stability achieved. *Distraction histiogenesis* - **Distraction histiogenesis** is the process by which new bone is formed between bone surfaces that are gradually pulled apart using an external fixator (**distraction osteogenesis**). - This is used in procedures like **limb lengthening** and is distinct from the direct healing of a fracture fixed with a plate.

Q: If the outer sheath and nerve fibres are intact and the inner axon is damaged, it is known as

Axonotmesis. ***Axonotmesis*** - This type of nerve injury involves damage to the **axon** itself, while the connective tissue layers (**endoneurium, perineurium, epineurium**) remain intact. - While the axon is disrupted, the preservation of the nerve's outer sheath allows for potential, albeit slow, **regeneration** of the axon. *Axonapraxia* - This term is not a standard classification of nerve injury. The correct term for a transient block in nerve conduction is **neurapraxia**. *Neurotmesis* - **Neurotmesis** is the most severe type of nerve injury, involving complete severance of the **axon** and all supporting **connective tissue sheaths**. - This type of injury requires **surgical repair** for any chance of functional recovery. *Neurapraxia* - **Neurapraxia** is the mildest form of nerve injury, characterized by a temporary **conduction block** without axonal damage. - Recovery is typically complete within days to weeks, as the **myelin sheath** may be temporarily dysfunctional but the axon remains intact.

Q: Tinel's sign is checking the regeneration of

Traumatised or sutured nerve. ***Traumatised or sutured nerve*** - **Tinel's sign** is a clinical test used to assess for nerve regeneration or irritation following injury or repair. - Percussion over the course of a damaged nerve elicits a **tingling sensation** or "pins and needles" in its distribution if regeneration is occurring or if the nerve is compressed. *Ruptured artery* - A ruptured artery is assessed through signs like **pulsatile bleeding**, **hematoma formation**, or **loss of distal pulses**, not by eliciting tingling sensations. - Management typically involves **surgical repair** or **ligation** to control hemorrhage and restore blood flow. *Vein rupture* - **Vein ruptures** typically present with non-pulsatile bleeding, hematoma, or visible bruising. - They are usually assessed with clinical signs and sometimes imaging, not through neurological percussion tests. *All of the options* - **Tinel's sign** is specifically associated with nerve pathology and regeneration, not vascular injuries. - The distinct clinical presentations and diagnostic approaches for arterial and venous injuries differ significantly from those for nerve damage.

Q: Healing of bone is affected by:

All of the options. ***All of the options*** - **Hypoxia**, **micromovement**, and **muscle interposition** are all factors known to impede or negatively affect the normal healing process of a bone fracture. - The successful healing of a bone fracture relies on a series of biological events that can be disrupted by these adverse conditions, leading to delayed union or non-union. *Hypoxia* - **Hypoxia**, or insufficient oxygen supply, impairs the metabolic activity of cells essential for bone healing, such as osteoblasts and chondrocytes. - It interferes with **angiogenesis**, the formation of new blood vessels, which is critical for delivering nutrients and oxygen to the healing bone. *Micromovement* - Excessive **micromovement** at the fracture site prevents the formation of a stable callus and can stimulate the development of fibrous tissue or cartilage instead of bone. - While some motion is beneficial, uncontrolled or excessive micromotion can lead to a **non-union** or pseudarthrosis, as it constantly disrupts the delicate tissue bridges attempting to form. *Muscle interposition* - **Muscle interposition** refers to muscle tissue becoming trapped between the bone fragments, physically separating them and preventing direct bone-to-bone contact. - This physical barrier inhibits the formation of the **fracture hematoma** and subsequent callus, thus mechanically hindering the healing process.

Q: Which of the following nerves has the best prognosis for repair after injury ?

Radial. ***Correct: Radial*** - The **radial nerve has the best prognosis** for repair among peripheral nerves after injury - It is predominantly a **motor nerve** with a relatively simple sensory distribution (posterior arm, forearm, and dorsal hand) - **Motor recovery is more predictable** compared to complex mixed nerves - Its **anatomical course** and branching pattern allow for better surgical access and repair outcomes - Literature consistently shows **better functional recovery rates** following radial nerve repair *Incorrect: Median* - The **median nerve** is a **complex mixed nerve** with extensive sensory and motor components - Injury results in loss of **thenar muscle function** and critical sensory loss in palmar digits - While recovery can be good, it is **not superior to radial nerve** due to the complexity of reinnervation required - Recovery of fine motor control and discriminative sensation is often incomplete *Incorrect: Lateral popliteal (Common peroneal)* - The **common peroneal nerve** has one of the **poorest prognoses** among peripheral nerves - Its **superficial location** around the fibular head makes it highly vulnerable to injury - **Long regeneration distances** from injury site to target muscles (foot dorsiflexors and evertors) - Frequently results in **persistent foot drop** even after repair *Incorrect: Ulnar* - The **ulnar nerve** has a **less favorable prognosis**, especially with proximal injuries at the elbow - Supplies **intrinsic hand muscles** requiring precise reinnervation for functional recovery - Injuries often result in **persistent claw hand deformity** and loss of fine motor coordination - **Delayed muscle atrophy** and long distances for regeneration contribute to poor outcomes

Q: Among the following options, which is the most common site of avascular necrosis?

Talus. ***Talus*** - The **talus** is highly susceptible to **avascular necrosis** due to its precarious blood supply, which primarily enters via the **tarsal canal** and **deltoid artery**. - Its large articular surface, about 60% covered by cartilage, limits direct soft tissue attachment and additional vascularity. *Head of the radius* - The **head of the radius** has a relatively robust blood supply from branches of the **radial recurrent artery**, making avascular necrosis less common. - While fractures can compromise local blood flow, it is not considered a primary site for idiopathic avascular necrosis. *Olecranon* - The **olecranon**, part of the ulna, receives a good collateral blood supply from anastomosing branches around the elbow, including the **posterior ulnar recurrent artery**. - Avascular necrosis here is rare and usually associated with severe trauma or specific medical conditions. *Medial condyle of femur* - Avascular necrosis of the **medial femoral condyle** primarily affects the subchondral bone and is often referred to as **osteonecrosis of the knee**. - While it can occur, particularly in older adults, it is less common than avascular necrosis of the talus or femoral head.

Q: All of the following factors affect osseointegration EXCEPT:

Patient's blood type. ***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.

Q: The following classification is used to estimate nerve injury:

Seddons classification. ***Seddons classification*** - The **Seddons classification** is a well-established system for classifying the severity of nerve injuries. - It categorizes nerve injuries into three main types: **neurapraxia**, **axonotmesis**, and **neurotmesis**. *Seddon's and Sunderland classification* - While both **Seddon's** and **Sunderland's classifications** are used for nerve injury, the question asks for "the following classification" implying a single, primary classification. - **Sunderland's classification** is a more detailed, five-grade system, often considered an extension of Seddon's. *Sunderland classification* - The **Sunderland classification** is a valid and widely used system, but it is not the *only* classification and the question implies a single, specific classification in its phrasing. - Sunderland's system provides more granular detail on the extent of nerve damage compared to Seddon's, with five degrees of injury. *None of the options* - This option is incorrect because the **Seddons classification** is indeed a valid and frequently used method for estimating nerve injury. - There are established classification systems for nerve injuries.

Q: Healing by Haversian remodeling is a type of:

Primary healing.. ***Primary healing*** - This term refers to **direct healing**, where bone fragments are in contact and movement is minimized, leading to direct bone formation without significant callus. - **Haversian remodeling**, common in rigid internal fixation, is the hallmark of primary bone healing, involving direct osteon formation across the fracture site. *Tertiary healing* - This is **not a recognized term** in the classification of bone healing processes. - Bone healing is generally categorized as primary (direct) or secondary (indirect). *Secondary healing* - This involves the formation of a **soft and then hard callus** in cases of unreduced or mobile fractures. - It is characterized by three overlapping phases: **inflammation, repair**, and **remodeling**, and does not primarily rely on Haversian remodeling. *Intermediate healing* - This is **not a formal classification** of bone healing. - Bone healing is typically dichotomized into primary and secondary healing, depending on the stability and reduction of the fracture.

Q: Following are the common sites of Avascular necrosis, EXCEPT:

Patella. ***Patella*** - The patella is rarely affected by **avascular necrosis (AVN)** due to its robust and redundant blood supply, making it an exception to common AVN sites. - While patellar fractures can compromise local blood flow, spontaneous or atraumatic AVN of the patella is exceedingly uncommon compared to other skeletal sites. *Head of the femur* - The **femoral head** is the most common site for **avascular necrosis** due to its precarious blood supply, especially after trauma (e.g., hip dislocation, femoral neck fracture) or in systemic conditions. - Its blood supply relies heavily on the **medial circumflex femoral artery**, which can be easily disrupted. *The body of talus* - The **talus** is highly susceptible to **avascular necrosis**, particularly after fractures or dislocations, as its blood supply enters through a limited number of soft tissue attachments. - The **body of the talus** receives a significant portion of its blood supply from vessels that can be easily compromised by injury. *Proximal half of scaphoid* - The **proximal pole of the scaphoid** is notoriously prone to **avascular necrosis** following scaphoid fractures because its blood supply enters primarily from the distal pole. - A disruption of blood flow (e.g., via the **dorsal carpal branch** of the radial artery) due to a fracture can lead to **non-union** and AVN of the proximal fragment.

Question 1

The X-ray shows plating done for a fracture. How does this fracture heal?

Accepted Answer

Primary healing

Answer

Secondary healing

Answer

Tertiary healing

Answer

Distraction histiogenesis

Question 2

If the outer sheath and nerve fibres are intact and the inner axon is damaged, it is known as

Accepted Answer

Axonotmesis

Answer

Axonapraxia

Answer

Neurotmesis

Answer

Neurapraxia

Question 3

Tinel's sign is checking the regeneration of

Accepted Answer

Traumatised or sutured nerve

Answer

Ruptured artery

Answer

Vein rupture

Answer

All of the options

Question 4

Healing of bone is affected by:

Accepted Answer

All of the options

Answer

Hypoxia

Answer

Micromovement

Answer

Muscle interposition

Question 5

Which of the following nerves has the best prognosis for repair after injury ?

Accepted Answer

Radial

Answer

Median

Answer

Ulnar

Answer

Lateral popliteal

Question 6

Among the following options, which is the most common site of avascular necrosis?

Accepted Answer

Talus

Answer

Head of the radius

Answer

Olecranon

Answer

Medial condyle of femur

Question 7

All of the following factors affect osseointegration EXCEPT:

Accepted Answer

Patient's blood type

Answer

Biocompatibility of implant material.

Answer

Implant design.

Answer

Status of the host bed.

Question 8

The following classification is used to estimate nerve injury:

Accepted Answer

Seddons classification

Answer

Seddon's and Sunderland classification

Answer

Sunderland classification

Answer

None of the options

Question 9

Healing by Haversian remodeling is a type of:

Accepted Answer

Primary healing.

Answer

Tertiary healing.

Answer

Secondary healing.

Answer

Intermediate healing.

Question 10

Following are the common sites of Avascular necrosis, EXCEPT:

Accepted Answer

Patella

Answer

Head of the femur

Answer

The body of talus

Answer

Proximal half of scaphoid

Basic Science in Orthopaedics — MCQs

Basic Science in Orthopaedics — MCQs

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