Wrist Arthroscopy — MCQs

10 questions

A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?

The image shows a highlighted region on the dorsal aspect of the hand (anatomical snuffbox). Which of the following anatomical structures form the boundaries or floor of this region?

Which of the following is NOT a complication of elbow dislocation?

The image shows a wrist deformity and an X-ray of a bone lesion near the distal radius. Based on the clinical and radiological features, what is the most likely diagnosis?

Median nerve injury at the wrist is commonly tested by.

Finkelstein's test is done for diagnosis of:

Heller's myotomy is done for

Fracture shaft of humerus can cause damage to which of the following nerves?

The most commonly involved nerve in lunate dislocation is -

Q10

Which of the following statement(s) is/are true?

Wrist Arthroscopy Indian Medical PG Practice Questions and MCQs

Question 1: A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?

A. Posterior Interosseous nerve injury (Correct Answer)
B. Radial nerve injury
C. Ulnar nerve injury
D. Median nerve injury

Explanation: Posterior Interosseous Nerve (PIN) injury - The Posterior Interosseous Nerve is the deep motor branch of the radial nerve that specifically innervates the extensor muscles of the fingers and thumb - These muscles include: Extensor Digitorum, Extensor Indicis, Extensor Digiti Minimi, Extensor Pollicis Longus and Brevis [1] - PIN injury causes inability to extend the MCP joints and interphalangeal joints of the fingers [1] - Wrist extension is preserved because the Extensor Carpi Radialis Longus (ECRL) and often ECRB are innervated by the radial nerve proper before it gives off the PIN [1] - This results in a characteristic finger drop without wrist drop Radial nerve injury - A high radial nerve injury (proximal, above the elbow) would cause both wrist drop AND finger extension loss - However, radial nerve injury at the spiral groove (most common site) typically spares the PIN or affects it less severely - The question asks specifically about isolated inability to extend MCP joints, which is the hallmark of PIN injury, not general radial nerve injury - Radial nerve proper gives branches to triceps, brachioradialis, and ECRL before dividing into PIN and superficial branch Ulnar nerve injury - The ulnar nerve innervates intrinsic hand muscles (interossei, lumbricals to digits 4-5, hypothenar muscles, adductor pollicis) [1] - Ulnar nerve injury causes claw hand deformity with MCP hyperextension (not loss of extension) and IP joint flexion - This is the opposite of what is described in the question Median nerve injury - The median nerve innervates the thenar muscles, lateral two lumbricals, and forearm flexors [1] - Median nerve injury causes ape hand deformity with loss of thumb opposition and flexion - It does not affect MCP joint extension, which is an extensor function

Question 2: The image shows a highlighted region on the dorsal aspect of the hand (anatomical snuffbox). Which of the following anatomical structures form the boundaries or floor of this region?

A. Abductor pollicis longus muscle.
B. Styloid process of the radius.
C. Extensor pollicis longus muscle.
D. All of the above anatomical structures. (Correct Answer)

Explanation: ***All of the above anatomical structures.*** - The image highlights the **anatomical snuffbox**, a triangular depression on the radial dorsal aspect of the hand. Its boundaries are formed by the tendons of the **extensor pollicis longus muscle** (ulnar side), and the **abductor pollicis longus** and **extensor pollicis brevis muscles** (radial side). - The **styloid process of the radius** forms the floor of the anatomical snuffbox along with the scaphoid and trapezium bones. All the options listed are key anatomical features associated with this region. *Extensor pollicis longus muscle.* - This muscle forms the **ulnar (medial) border** of the anatomical snuffbox. - Its tendon can be palpated during **thumb extension** and contributes to the overall structure of the highlighted area. *Abductor pollicis longus muscle.* - This muscle, along with the extensor pollicis brevis, forms the **radial (lateral) border** of the anatomical snuffbox. - Its tendon is visible and palpable on the radial side of the highlighted region when the thumb is abducted. *Styloid process of the radius.* - This bony prominence is located at the **distal end of the radius** on the radial side of the wrist. - It forms part of the **proximal floor** of the anatomical snuffbox, contributing to its definition.

Question 3: Which of the following is NOT a complication of elbow dislocation?

A. Vascular injury
B. Median nerve injury
C. Myositis ossificans
D. Radial nerve injury (Correct Answer)

Explanation: ***Radial nerve injury*** - The **radial nerve** is rarely injured in an elbow dislocation due to its anatomical course, which is less exposed to the shearing forces involved in this type of injury. - While other nerves like the ulnar and median nerves are more susceptible, significant stretching or compression of the radial nerve is **uncommon** in typical elbow dislocations. *Vascular injury* - The **brachial artery** runs in close proximity to the elbow joint and can be torn or compressed during a dislocation, leading to **ischemia** if not promptly recognized and treated. - This complication can result in **Volkmann's ischemic contracture** if perfusion is not restored. *Median nerve injury* - The **median nerve** passes anterior to the elbow joint and is vulnerable to injury from stretching or direct compression during dislocation. - Injury can manifest as **sensory deficits** in the distribution of the median nerve and **weakness** of forearm pronation and thumb flexion/opposition. *Myositis ossificans* - This is a common chronic complication of elbow dislocations, particularly in cases of **delayed reduction** or aggressive physical therapy. - It involves the **abnormal ossification** of soft tissues around the joint, commonly in the brachialis muscle, leading to **pain and restricted range of motion**.

Question 4: The image shows a wrist deformity and an X-ray of a bone lesion near the distal radius. Based on the clinical and radiological features, what is the most likely diagnosis?

A. Ewings Sarcoma
B. Osteochondroma
C. Giant Cell Tumor (GCT) (Correct Answer)
D. Osteoid Osteoma

Explanation: ***Giant Cell Tumor (GCT)*** * The image shows a **lytic (lucid) lesion** located in the **epiphysis/metaphysis of the distal radius**, which is a classic presentation site for GCT. * GCTs are typically seen in individuals aged 20-40, often present with **pain, swelling, and reduced range of motion**, and can show a **soap bubble appearance** on X-ray even with cortical erosion as seen in the image. *Ewing's Sarcoma* * Ewing's Sarcoma commonly affects the **diaphysis of long bones** and may present with an **onion skin periosteal reaction**, none of which are clearly depicted. * It primarily affects children and young adults (5-20 years old), which does not align with the assumed adult presentation given the fused epiphysis. *Osteochondroma* * Osteochondromas are **bony prominences covered by cartilage** and grow **outward from the bone surface**, often away from the joint, unlike the intraosseous lytic lesion seen. * They typically appear as **pedunculated or sessile exostoses** and are benign growth plate abnormalities, not lytic lesions of the marrow cavity. *Osteoid Osteoma* * Osteoid osteomas are characterized by a **small lucent nidus** (usually <1.5 cm) surrounded by a significant margin of **sclerotic bone**, which is not seen here. * They classically cause **nocturnal pain** relieved by NSAIDs and are typically smaller than the lesion depicted, which appears expansile.

Question 5: Median nerve injury at the wrist is commonly tested by.

A. Contraction of abductor pollicis brevis (Correct Answer)
B. Loss of sensation on palm
C. Loss of sensation on ring finger
D. Contraction of flexor pollicis brevis

Explanation: ***Contraction of abductor pollicis brevis*** - The **abductor pollicis brevis (APB)** is primarily innervated by the **median nerve**, and its motor function is often the **first to be affected** and is a reliable test for median nerve integrity at the wrist. - Testing the **abduction of the thumb** against resistance (often called the "OK" sign or simply checking for strength) directly assesses the function of the APB and therefore the median nerve. *Contraction of flexor pollicis brevis* - The **flexor pollicis brevis (FPB)** has a **dual innervation**; its superficial head is supplied by the median nerve, but its deep head is often supplied by the ulnar nerve. - This dual innervation makes its contraction an unreliable isolated test for median nerve injury, as ulnar nerve compensation might mask a median nerve deficit. *Loss of sensation on palm* - While the median nerve supplies sensation to the radial side of the palm, an injury at the wrist, specifically within the **carpal tunnel**, typically spares the palmar cutaneous branch. - The **palmar cutaneous branch** of the median nerve arises proximal to the carpal tunnel and provides sensation to the thenar eminence and central palm, so its sensation is often preserved even with significant carpal tunnel syndrome. *Loss of sensation on ring finger* - The **ring finger** receives sensory innervation from both the **median nerve** (radial half) and the **ulnar nerve** (ulnar half). - Therefore, isolated loss of sensation on the ring finger would not be a definitive test for median nerve injury alone, as it requires assessment of both nerve distributions.

Question 6: Finkelstein's test is done for diagnosis of:

A. Trigger finger (stenosing tenosynovitis)
B. Acute compartment syndrome
C. De quervain's tenosynovitis (Correct Answer)
D. Carpal tunnel syndrome

Explanation: ***De Quervain's tenosynovitis*** - **Finkelstein's test** is the classic physical examination maneuver used to diagnose **De Quervain's tenosynovitis**. - The test involves pain elicited when the patient makes a **fist with the thumb tucked inside** the other fingers, and then ulnar deviates the wrist. *Trigger finger (stenosing tenosynovitis)* - While it is also a tenosynovitis, **trigger finger** affects the flexor tendons of the digits and is characterized by painful clicking or locking. - Diagnosis is clinical, based on observing the **finger catching or locking** during attempted extension. *Acute compartment syndrome* - This is a limb-threatening condition involving increased pressure within a muscle compartment, often due to trauma. - Diagnosis is based on **clinical signs** (pain out of proportion, pallor, paresthesia, pulselessness, paralysis) and **intracompartmental pressure measurements**. *Carpal tunnel syndrome* - This condition results from compression of the **median nerve** within the carpal tunnel, causing numbness, tingling, and weakness in the hand. - Diagnostic tests include **Tinel's sign** (tapping over the median nerve) and **Phalen's maneuver** (wrist flexion), not Finkelstein's test.

Question 7: Heller's myotomy is done for

A. Zenker's diverticulum
B. Achalasia cardia (Correct Answer)
C. Hiatus hernia
D. Diffuse esophageal spasm

Explanation: ***Achalasia cardia*** - **Heller's myotomy** (esophagomyotomy) is the definitive surgical treatment for **achalasia cardia** - The procedure involves cutting the circular muscle fibers of the **lower esophageal sphincter (LES)** to relieve the functional obstruction - It addresses the primary pathology of achalasia: **failure of LES relaxation** and absence of esophageal peristalsis - Often combined with a partial fundoplication (Dor or Toupet) to prevent postoperative reflux *Zenker's diverticulum* - This is a **pharyngeal pouch** that develops at the pharyngoesophageal junction (Killian's triangle) - Treated with **diverticulectomy or diverticulopexy** with cricopharyngeal myotomy - Involves the upper esophageal sphincter, not the LES targeted by Heller's myotomy *Diffuse esophageal spasm* - A primary esophageal motility disorder characterized by **simultaneous, non-peristaltic contractions** - While esophageal myotomy may occasionally be considered in refractory cases, it is not the standard procedure - Management is primarily **medical** (calcium channel blockers, nitrates) rather than surgical *Hiatus hernia* - Involves herniation of the stomach through the esophageal hiatus of the diaphragm - Treated with **fundoplication** (Nissen or partial fundoplication) to reinforce the LES and repair the hiatus - Does not involve cutting the LES muscle as in Heller's myotomy

Question 8: Fracture shaft of humerus can cause damage to which of the following nerves?

A. Ulnar nerve
B. Radial nerve (Correct Answer)
C. Axillary nerve
D. Median nerve

Explanation: ***Radial nerve*** - The **radial nerve** runs in the **spiral groove** along the posterior aspect of the humerus shaft, making it highly susceptible to injury during a fracture in this region. - Damage can lead to **wrist drop** and impaired sensation over the posterior forearm and hand. *Ulnar nerve* - The **ulnar nerve** primarily runs along the medial epicondyle of the humerus, making it more vulnerable to injuries around the **elbow joint**, not typically the humeral shaft. - Injury to the ulnar nerve results in a characteristic **"claw hand"** deformity and sensory loss over the medial aspect of the hand. *Axillary nerve* - The **axillary nerve** wraps around the surgical neck of the humerus and is most commonly injured with **shoulder dislocations** or fractures involving the surgical neck, not the shaft. - Damage to the axillary nerve causes weakness in **deltoid abduction** and sensory loss over the lateral shoulder (regimental badge area). *Median nerve* - The **median nerve** travels more anteriorly and medially in the arm and is generally protected from direct injury in a mid-shaft humeral fracture. - Injury to the median nerve can cause a **"ape hand" deformity** and sensory loss over the radial aspect of the palm.

Question 9: The most commonly involved nerve in lunate dislocation is -

A. Ulnar nerve
B. Median nerve (Correct Answer)
C. Posterior interosseous
D. Anterior interosseous

Explanation: ***Median nerve*** - In a **lunate dislocation**, the lunate bone dislocates anteriorly and rotates. This displaced lunate can directly compress the **median nerve** within the carpal tunnel, which lies just anterior to it. - Compression of the median nerve leads to symptoms of **carpal tunnel syndrome**, including numbness and tingling in the thumb, index, middle, and radial half of the ring finger. *Ulnar nerve* - The **ulnar nerve** passes through Guyon's canal, which is located more medially and is generally not directly compressed by an isolated lunate dislocation. - While other wrist injuries can affect the ulnar nerve, it is not the most common nerve involved in lunate dislocation. *Posterior interosseous* - The **posterior interosseous nerve** is a branch of the radial nerve and supplies muscles in the posterior compartment of the forearm; it is located away from the carpal bones and is very rarely affected by lunate dislocation. - Injury to this nerve typically results in wrist drop or issues with finger extension. *Anterior interosseous* - The **anterior interosseous nerve** is a branch of the median nerve that supplies deep flexor muscles in the forearm; it also lies away from the direct path of a dislocated lunate. - Injury to this nerve leads to an inability to make the "ok" sign due to paralysis of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 10: Which of the following statement(s) is/are true?

A. Normally the radial styloid is 1/2 lower than the ulnar
B. Dinner fork deformity is characteristic of Colles' fracture (Correct Answer)
C. All of the options
D. Oedema & tenderness over the anatomical snuffbox is the characteristic features of Fracture of the scaphoid

Explanation: **Dinner fork deformity is characteristic of Colles' fracture** - **Colles' fracture** involves a **dorsal displacement** and angulation of the distal radius, creating a characteristic **"dinner fork" or "bayonet" deformity** of the wrist. - This specific deformity is a classic clinical sign that aids in the diagnosis of a Colles' fracture, which is an **extra-articular fracture** of the distal radius with dorsal angulation. *Normally the radial styloid is 1/2 lower than the ulnar* - The **radial styloid** normally extends approximately **1-1.5 cm (or about 1/2 inch)** *distal* to the ulnar styloid, not lower than. - This difference in length is crucial for normal wrist kinematics, and its reversal can indicate conditions like **ulnar positive variance**. *All of the options* - This option is incorrect because the statement regarding the radial styloid being lower than the ulnar is **false**. - Since one of the options provided is factually incorrect, this choice cannot be true. *Oedema & tenderness over the anatomical snuffbox is the characteristic features of Fracture of the scaphoid* - While **oedema and tenderness in the anatomical snuffbox** are hallmark signs of a **scaphoid fracture**, this statement alone does not encompass all the truth presented in the options. - This specific physical finding is highly indicative of a scaphoid fracture, necessitating further imaging to confirm the diagnosis due to **poor vascular supply** to the scaphoid and risk of **avascular necrosis**.

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