Upper Limb Prosthetics — MCQs
Extensive surgical debridement, decompression or amputation may be indicated in the following clinical setting except
Which of the following is NOT a hybrid muscle?
All of the following factors affect osseointegration EXCEPT:
The electromyogram (EMG) is least useful for the diagnosis of:
A 40-year old male after binge drinking slept on a chair. On the next day, he presented with weakness of the right arm and was not able to move his hand. Examination showed radial nerve palsy. What would be the management?
Which of the following is the commonest material used to make an orthopedic implant?
Shortest functional level of trans tibial amputation is:
In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:
A 12-year-old boy presents with weak pulses in the upper limbs, a blood pressure of 90/60 mmHg , and retinal hemorrhages. What is the most likely diagnosis?
What is the characteristic upper limb deformity seen in Erb's palsy?
Upper Limb Prosthetics Indian Medical PG Practice Questions and MCQs
Question 1: Extensive surgical debridement, decompression or amputation may be indicated in the following clinical setting except
- A. Acute rhabdomyolysis
- B. Acute haemolytic streptococcal cellulitis
- C. Acute thrombophlebitis (Correct Answer)
- D. Progressive synergistic gangrene
Explanation: ***Acute thrombophlebitis*** - This condition involves inflammation and **thrombosis** of a superficial vein, typically managed with **anticoagulation**, pain relief, and local measures. - Surgical intervention like debridement, decompression, or amputation is generally **not indicated** unless there are severe complications such as infection or extensive tissue necrosis, which are rare. *Acute rhabdomyolysis* - Severe rhabdomyolysis can lead to **compartment syndrome**, necessitating fasciotomy (decompression) to prevent irreversible muscle and nerve damage. - In cases of extensive muscle necrosis, **surgical debridement** may be required to remove non-viable tissue and prevent further systemic complications. *Acute haemolytic streptococcal cellulitis* - While initial management is antibiotics, rapidly progressing necrotizing infections (like **necrotizing fasciitis**, a severe form often caused by *Streptococcus pyogenes*) require **extensive surgical debridement** to remove dead tissue and control the spread of infection. - Delayed debridement can lead to systemic toxicity, limb loss, or death, making aggressive surgical intervention crucial. *Progressive synergistic gangrene* - Also known as **Meleney's gangrene**, this rare but severe soft tissue infection requires aggressive and **extensive surgical debridement** of all necrotic tissue. - The combination of aerobic and anaerobic bacteria creates a progressive, destructive lesion that can necessitate amputation if not adequately controlled by debridement.
Question 2: Which of the following is NOT a hybrid muscle?
- A. Sternocleidomastoid
- B. Flexor pollicis brevis
- C. Brachialis
- D. Adductor pollicis (Correct Answer)
Explanation: ***Adductor pollicis*** - The adductor pollicis is solely innervated by the **deep branch of the ulnar nerve (C8, T1)**, making it a non-hybrid muscle. - Its primary actions are **adduction, opposition, and flexion of the thumb**. *Sternocleidomastoid* - This muscle is considered hybrid because it is innervated by two different nerves: the **spinal accessory nerve (CN XI)** and branches from the **cervical plexus (C2-C3)**. - The spinal accessory nerve innervates primarily the motor function, while the cervical plexus provides proprioceptive fibers. *Flexor pollicis brevis* - This muscle often has a dual innervation, with its superficial head supplied by the **median nerve** and its deep head by the **ulnar nerve** [1]. - This dual innervation pattern qualifies it as a hybrid muscle [1]. *Brachialis* - The brachialis muscle is typically innervated by the **musculocutaneous nerve (C5, C6)**, but it also receives a small contribution from the **radial nerve (C7)**. - This additional supply from the radial nerve makes it a hybrid muscle.
Question 3: 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 4: The electromyogram (EMG) is least useful for the diagnosis of:
- A. Myasthenia gravis
- B. Charcot-Marie-Tooth disease
- C. Spinal muscular atrophy
- D. Cerebral palsy (Correct Answer)
Explanation: ***Cerebral palsy*** - Cerebral palsy is a **disorder of movement and posture** caused by non-progressive brain damage, primarily affecting the **upper motor neurons**. - While EMG can assess muscle activity, its primary role is in evaluating **lower motor neuron diseases** and **neuromuscular junction disorders**, making it less directly useful for diagnosing a central nervous system disorder like cerebral palsy. *Myasthenia gravis* - EMG, particularly **repetitive nerve stimulation**, is highly useful for diagnosing myasthenia gravis by revealing a **decremental response** in the compound muscle action potential due to impaired neuromuscular transmission [1]. - It directly assesses the function of the **neuromuscular junction**, which is the site of pathology in myasthenia gravis [1]. *Charcot-Marie-Tooth disease* - EMG and **nerve conduction studies (NCS)** are crucial for diagnosing Charcot-Marie-Tooth disease by demonstrating **abnormal nerve conduction velocities** (demyelinating forms) or **reduced amplitude** of compound muscle action potentials (axonal forms) which indicate peripheral nerve damage. - The findings help characterize the type and severity of **peripheral neuropathy**, a hallmark of this condition. *Spinal muscular atrophy* - EMG is essential for diagnosing spinal muscular atrophy by showing **denervation and reinnervation changes** in muscles, such as **fibrillations**, **positive sharp waves**, and **large-amplitude, long-duration motor unit potentials** [1]. - These findings reflect the loss of **anterior horn cells** and subsequent attempts by surviving motor neurons to reinnervate muscle fibers.
Question 5: A 40-year old male after binge drinking slept on a chair. On the next day, he presented with weakness of the right arm and was not able to move his hand. Examination showed radial nerve palsy. What would be the management?
- A. Neurolysis
- B. Instant exploration
- C. Electromyography after 2 days and decide after results
- D. Give a knuckle bender splint (Correct Answer)
Explanation: ***Give a knuckle bender splint*** - This patient presents with features of **Saturday Night Palsy** (radial nerve compression from prolonged pressure), which is typically a **neurapraxia**. - Management for neurapraxia usually involves **conservative measures** like splinting to support the wrist and fingers, protecting the nerve, and allowing for spontaneous recovery, which typically occurs within weeks to months. *Neurolysis* - **Neurolysis** (surgical freeing of a nerve from scar tissue) is an invasive procedure generally reserved for cases of **nerve entrapment** or persistent compression that have failed conservative therapy or show signs of ongoing nerve damage. - Given the acute presentation and typical course of Saturday Night Palsy, it is too premature and often unnecessary for this type of injury, where spontaneous recovery is common. *Instant exploration* - **Instant surgical exploration** of the nerve is usually only indicated in cases of **acute, severe trauma** where nerve transection or severe crush injury is suspected, or when there are clear signs of progressive nerve dysfunction. - In Saturday Night Palsy, the injury is typically a **mild compression (neurapraxia)**, making immediate surgery unwarranted and potentially more harmful than beneficial. *Electromyography after 2 days and decide after results* - **Electromyography (EMG)** and **nerve conduction studies (NCS)** are valuable diagnostic tools but have limitations in the very acute phase of a nerve injury. - **EMG changes (denervation potentials)** typically take 2-3 weeks to develop after an injury, so performing it after only two days would likely yield normal results and not provide useful information for immediate management.
Question 6: Which of the following is the commonest material used to make an orthopedic implant?
- A. Methyl-methacrylate
- B. Polyethylene (UHMWPE)
- C. Titanium (Correct Answer)
- D. Stainless steel
Explanation: ***Titanium*** - **Titanium** and its alloys (e.g., Ti-6Al-4V) are widely favored for orthopedic implants due to their **excellent biocompatibility**, high strength-to-weight ratio, and corrosion resistance. - Its **osseointegrative properties** allow bone to grow directly onto the implant surface, providing stable fixation without an intervening fibrous layer. *Methyl-methacrylate* - **Methyl-methacrylate** is primarily used as a **bone cement** (PMMA) to fix implants to bone, rather than as the primary material for the implant itself. - It provides immediate mechanical stability but does not integrate with bone. *Polyethylene (UHMWPE)* - **Ultra-high molecular weight polyethylene (UHMWPE)** is commonly used as a bearing surface in joint replacements (e.g., acetabular liner in hip replacements) for its **low friction** and good wear resistance. - It is not typically used for the structural components of the implant that bear the primary load. *Stainless steel* - **Stainless steel** (e.g., 316L) was historically a common implant material, particularly for temporary fixation devices like plates and screws. - While it has good strength and corrosion resistance, it generally has a **lower biocompatibility** and more elastic modulus mismatch with bone compared to titanium, making it less preferred for permanent, load-bearing implants.
Question 7: Shortest functional level of trans tibial amputation is:
- A. Just proximal to tibial tuberosity
- B. 15 cm distal to joint line
- C. 10 cm distal to joint line
- D. Just distal to tibial tuberosity (Correct Answer)
Explanation: **Just distal to tibial tuberosity** - This level allows for a **short residual limb** but still provides sufficient leverage for effective prosthetic control and weight-bearing. - Amputations at this level generally preserve the **knee joint**, which is crucial for maximizing function and ambulation. *Just proximal to tibial tuberosity* - An amputation **proximal to the tibial tuberosity** would result in a **knee disarticulation** or above-knee amputation, leading to a much greater functional deficit. - This level means losing the **knee joint**, which is not considered a trans-tibial amputation. *15 cm distal to joint line* - This level of amputation would result in a **longer residual limb** than necessary, which can be beneficial, but it's not the *shortest functional* level. - While functional, a longer limb might sometimes present challenges with prosthetic fit or bulk in certain situations. *10 cm distal to joint line* - Similar to 15 cm distal, this length is considered a **standard or optimal length** for trans-tibial amputations, resulting in good function. - However, it is not the **shortest possible functional level** while still retaining an effective limb for prosthetic use.
Question 8: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:
- A. Coracoacromial ligament
- B. Costoclavicular ligament
- C. Coracoclavicular ligament (Correct Answer)
- D. Coracohumeral ligament
Explanation: ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is a strong extra-articular ligament that connects the **coracoid process** of the scapula to the **inferior surface of the clavicle**, effectively suspending the scapula from the clavicle. - This ligament plays the **primary and crucial role** in transmitting forces from the upper limb through the **scapula and clavicle** to the **axial skeleton**, particularly during weight-bearing activities. - It is the key structure that maintains the connection between the upper limb (via scapula) and the axial skeleton (via clavicle). *Coracoacromial ligament* - The **coracoacromial ligament** forms the roof of the **subacromial space** and is primarily involved in preventing superior displacement of the humeral head. - It does not transmit the weight of the upper limb to the axial skeleton but rather protects structures within the subacromial space by forming the coracoacromial arch. *Costoclavicular ligament* - The **costoclavicular ligament** connects the **first rib to the clavicle**, stabilizing the **sternoclavicular joint**. - While it provides important stability at the sternoclavicular joint (part of the transmission pathway), the primary transmission of upper limb weight occurs through the **coracoclavicular ligament** connecting the scapula to clavicle. *Coracohumeral ligament* - The **coracohumeral ligament** connects the **coracoid process of the scapula** to the **greater and lesser tubercles of the humerus**, reinforcing the shoulder joint capsule. - It primarily helps support the weight of the upper limb when the arm is adducted, but it does not transmit this weight to the axial skeleton.
Question 9: A 12-year-old boy presents with weak pulses in the upper limbs, a blood pressure of 90/60 mmHg , and retinal hemorrhages. What is the most likely diagnosis?
- A. Henoch-Schönlein purpura (HSP)
- B. Polyarteritis nodosa (PAN)
- C. Takayasu arteritis (Correct Answer)
- D. Microscopic polyangiitis
Explanation: ***Takayasu arteritis*** - **Weak pulses** in the upper limbs, **lower blood pressure** (90/60 mmHg), and **retinal hemorrhages** are classic signs of Takayasu arteritis, which primarily affects the aortic arch and its major branches. [1] - This condition is also known as "pulseless disease" due to the significant narrowing of peripheral arteries, leading to diminished or absent pulses. [1] *Henoch-Schönlein purpura (HSP)* - HSP is characterized by a **palpable purpuric rash**, **arthralgia**, **abdominal pain**, and **renal involvement** (hematuria/proteinuria), none of which are explicitly mentioned here. - It typically affects **small vessels** and does not cause weak pulses in the upper limbs or systemic hypotension in this manner. *Polyarteritis nodosa (PAN)* - PAN is a **necrotizing vasculitis** of medium-sized arteries, often presenting with **fever**, **weight loss**, **myalgia**, and visceral infarcts. - While it can affect various organs, it does not typically cause the specific pattern of weak upper limb pulses and retinal hemorrhages observed here, which points to large vessel involvement. *Microscopic polyangiitis* - This is a **small-vessel vasculitis** characterized by **glomerulonephritis** and **pulmonary capillaritis**, often presenting with hemoptysis and rapidly progressive renal failure. - It does not cause the large vessel symptoms like weak upper limb pulses or significant systemic hypotension seen in the patient.
Question 10: What is the characteristic upper limb deformity seen in Erb's palsy?
- A. Adduction and lateral rotation of arm
- B. Adduction and medial rotation of arm (Correct Answer)
- C. Abduction and lateral rotation of arm
- D. Abduction and medial rotation of arm
Explanation: ***Adduction and medial rotation of arm*** - Erb's palsy, resulting from injury to the **upper brachial plexus** (C5-C6 nerve roots), primarily affects the **deltoid**, **supraspinatus**, **infraspinatus**, and **biceps** muscles. - The unopposed action of unaffected muscles, such as the **pectoris major** and **latissimus dorsi**, leads to the characteristic **waiter's tip position**, involving **adduction** and **medial rotation** of the arm. *Adduction and lateral rotation of arm* - This position would imply weakness of the **pectoralis major** and **latissimus dorsi** and stronger activity of the **infraspinatus** and **teres minor**, which is contrary to the muscle deficits in Erb's palsy. - **Lateral rotation** of the arm is typically impaired in Erb's palsy due to weakness of the **infraspinatus** and **teres minor**. *Abduction and lateral rotation of arm* - **Abduction** is severely impacted in Erb's palsy due to paralysis of the **deltoid** and **supraspinatus**. - This position would suggest intact function of muscles that are explicitly weakened or paralyzed in Erb's palsy. *Abduction and medial rotation of arm* - While **medial rotation** can be a component of the deformity, **abduction** is a movement that is significantly impaired in Erb's palsy, making this option incorrect. - The inability to abduct the arm is a hallmark of the condition due to weakness of the **deltoid** and **supraspinatus**.
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