Biomechanics of Hip — MCQs

10 questions

Trendelenburg sign is positive due to the involvement of:

Antalgic hip gait is related to which of the following?

A 70-year-old woman with chronic osteoarthritis of the hip presents with worsening pain and limited mobility despite conservative management. What is the next appropriate step?

Trendelenberg test is negative in

Defect in Gluteus Maximus lead to all of the following, EXCEPT:

Which of the following fractures of the neck of femur are associated with maximal compromise in blood supply ?

Trendelenburg test is positive due to injury to which of the following nerves?

Trendelenburg's sign is positive in injury to which structure?

The following gait is seen due to weakness of:

Q10

What is the best treatment for a 60-year-old man with intracapsular femoral neck fracture?

Biomechanics of Hip Indian Medical PG Practice Questions and MCQs

Question 1: Trendelenburg sign is positive due to the involvement of:

A. Gluteus maximus
B. Psoas major
C. Gluteus medius (Correct Answer)
D. Adductor magnus

Explanation: ***Gluteus medius*** - The **Trendelenburg sign** indicates weakness or paralysis of the hip abductor muscles, primarily the **gluteus medius** and **gluteus minimus**. - When standing on one leg, these muscles contract on the supported side to keep the pelvis level; if they are weak, the unsupported side of the pelvis drops. *Gluteus maximus* - This muscle is the primary **extensor of the hip** and is crucial for activities like climbing stairs or standing up from a seated position. - Its weakness would primarily affect hip extension, not the ability to keep the pelvis level during single-leg stance. *Psoas major* - The **psoas major** is a powerful **hip flexor** and contributes to lumbar spine stability. - Weakness of this muscle would impair hip flexion, making it difficult to lift the leg forward, but it is not directly involved in stabilizing the pelvis in the frontal plane during standing. *Adductor magnus* - The **adductor magnus** is an important **hip adductor** and also functions as an extensor in certain positions. - Its primary role is to bring the leg towards the midline, and its weakness would not cause the characteristic pelvic drop seen in a positive Trendelenburg sign.

Question 2: Antalgic hip gait is related to which of the following?

A. Painful hip gait (Correct Answer)
B. Trendelenberg gait
C. Waddling gait
D. Short leg gait

Explanation: ***Painful hip gait*** - An **antalgic gait** is a deviation from a normal gait pattern caused by pain, most commonly experienced in the hip or knee. - The individual attempts to **minimize the time spent bearing weight** on the painful limb, resulting in a shortened stance phase on the affected side. *Waddling gait* - This gait is characterized by a **broad base** and a **swaying motion** from side to side, often due to weakness in the hip abductor muscles. - While sometimes seen in hip pathologies, it's not synonymous with an antalgic gait, which is specifically pain-driven. *Trendelenberg gait* - This gait occurs due to weakness of the **hip abductor muscles** (gluteus medius and minimus) on the stance leg, causing the pelvis to drop on the swing leg side. - It's a compensatory mechanism for muscle weakness, not directly caused by pain. *Short leg gait* - This gait arises from a **discrepancy in leg length**, leading to compensatory mechanisms like hip hiking or circumduction to clear the shorter limb during swing phase. - While it can lead to secondary pain, the primary cause is a structural difference, not acute pain influencing the weight-bearing phase.

Question 3: A 70-year-old woman with chronic osteoarthritis of the hip presents with worsening pain and limited mobility despite conservative management. What is the next appropriate step?

A. NSAIDs
B. Physical therapy
C. Intra-articular corticosteroid injections
D. Total hip replacement (Correct Answer)

Explanation: ***Total hip replacement*** - For **severe osteoarthritis (OA)** causing significant pain and **functional impairment** despite failed conservative management, **total hip replacement** is the most definitive and effective treatment. - This procedure alleviates pain and restores **mobility**, dramatically improving the patient's quality of life. *NSAIDs* - **NSAIDs** are typically part of **initial conservative management** for symptomatic relief in mild to moderate OA, but they have already failed in this patient. - Continued use in elderly patients carries risks of **gastrointestinal, renal, and cardiovascular side effects**, making it a less desirable long-term solution. *Physical therapy* - **Physical therapy** is a crucial component of conservative management to improve **strength, flexibility, and function**, but it often becomes insufficient in advanced OA. - Since this patient has worsening symptoms despite conservative measures, physical therapy alone is unlikely to provide adequate relief. *Intra-articular corticosteroid injections* - **Corticosteroid injections** can provide temporary pain relief by reducing inflammation but do not address the underlying **structural damage** of severe OA. - Their effectiveness diminishes over time, and repeated injections are discouraged due to potential cartilage damage.

Question 4: Trendelenberg test is negative in

A. Polio myelitis
B. Inferior Gluteal nerve
C. Normal hip function (Correct Answer)
D. Superior Gluteal nerve

Explanation: ***Normal hip function*** - A **negative Trendelenburg test** indicates that the hip abductor muscles (primarily the **gluteus medius and minimus**) are functioning correctly and can maintain pelvic stability when standing on one leg. - This suggests the absence of **weakness** or **dysfunction** in the hip abductors or their innervation. *Polio myelitis* - **Poliomyelitis** can cause **paralysis** and **weakness** of various muscles, including the hip abductors, leading to a **positive Trendelenburg test**. - The disease damages **motor neurons** in the spinal cord, impairing muscle function. *Inferior Gluteal nerve* - The **inferior gluteal nerve** primarily innervates the **gluteus maximus**, which is responsible for hip extension, not hip abduction. - Weakness due to inferior gluteal nerve damage would manifest as difficulty with activities like **climbing stairs** or **rising from a chair**, but typically would not cause a positive Trendelenburg test. *Superior Gluteal nerve* - The **superior gluteal nerve** innervates the **gluteus medius and minimus**, which are the primary hip abductors. - Damage to this nerve or weakness of these muscles would result in a **positive Trendelenburg test**, where the contralateral pelvis drops when standing on the affected leg.

Question 5: Defect in Gluteus Maximus lead to all of the following, EXCEPT:

A. Extension defect
B. Difficulty in straightening from the bending position
C. Difficulty rising from the sitting position
D. Positive Trendelenburg's sign (Correct Answer)

Explanation: ***Positive Trendelenburg's sign*** - A positive Trendelenburg's sign indicates weakness of the **gluteus medius** and **minimus** muscles, which are primarily responsible for abducting the hip and stabilizing the pelvis during gait. - A defect in the **gluteus maximus** does not directly cause this sign, as its main function is hip extension. *Extension defect* - The **gluteus maximus** is the primary extensor of the hip joint. - A defect in this muscle would indeed lead to difficulty or weakness in performing **hip extension**. *Difficulty in straightening from the bending position* - Straightening from a bending position requires powerful **hip extension**, which is a primary function of the **gluteus maximus**. - Without a functional gluteus maximus, this movement would be significantly impaired. *Difficulty rising from the sitting position* - Rising from a sitting position involves strong **hip extension** and **knee extension**, with the gluteus maximus being crucial for the hip component. - A defect would make this everyday activity much more challenging.

Question 6: Which of the following fractures of the neck of femur are associated with maximal compromise in blood supply ?

A. Basicervical fracture
B. Trans cervical fracture
C. Sub Capital fractures (Correct Answer)
D. Intertrochanteric fractures

Explanation: ***Sub Capital fractures*** - These fractures occur at the anatomical **neck of the femur**, very close to the femoral head. - Due to their location, they disrupt the main blood supply to the femoral head, primarily from the **retinacular arteries**, leading to a high risk of **avascular necrosis**. *Trans cervical fracture* - This fracture occurs through the **midneck of the femur**, which is still within the intracapsular region. - While it has a significant risk of **ischemia**, the compromise is generally less severe than in subcapital fractures. *Intertrochanteric fractures* - These are **extracapsular fractures** occurring between the greater and lesser trochanters. - They tend to have an **excellent blood supply** and thus a low risk of avascular necrosis, but are associated with more significant blood loss and malunion issues. *Basicervical fracture* - This is an **intracapsular fracture** that occurs at the base of the femoral neck, near the junction with the trochanters. - Although intracapsular, its position is slightly more proximal than subcapital fractures, potentially leaving more of the **retinacular vessels** intact, resulting in a somewhat lower risk of avascular necrosis compared to subcapital fractures.

Question 7: Trendelenburg test is positive due to injury to which of the following nerves?

A. Superior Gluteal nerve (Correct Answer)
B. Obturator nerve
C. Inferior Gluteal nerve
D. Sciatic nerve

Explanation: ***Superior Gluteal nerve*** - A positive **Trendelenburg test** indicates weakness of the **gluteus medius** and **gluteus minimus** muscles, which are innervated by the **superior gluteal nerve**. - Injury to this nerve leads to the characteristic pelvic drop on the unsupported side during ambulation or unilateral stance. *Obturator nerve* - The **obturator nerve** primarily innervates the **adductor muscles** of the thigh. - Injury to this nerve would cause weakness in **thigh adduction**, not gluteal muscle dysfunction or a positive Trendelenburg sign. *Inferior Gluteal nerve* - The **inferior gluteal nerve** supplies the **gluteus maximus**, which is a powerful extensor and external rotator of the hip. - Damage to this nerve primarily affects hip extension, making rising from a seated position or climbing stairs difficult, but does not cause a positive Trendelenburg test. *Sciatic nerve* - The **sciatic nerve** is the largest nerve in the body, innervating the posterior thigh muscles and all muscles below the knee. - Injury to the sciatic nerve would cause widespread motor and sensory deficits in the leg and foot, but not specifically the weakness typical of a positive Trendelenburg sign.

Question 8: Trendelenburg's sign is positive in injury to which structure?

A. Gluteus maximus
B. Gluteus medius (Correct Answer)
C. Quadriceps femoris
D. Quadratus lumborum

Explanation: ***Gluteus medius*** - A positive **Trendelenburg's sign** indicates weakness or paralysis of the **gluteus medius** muscle, or problem with its innervation or hip joint. - This muscle is crucial for **abduction** and **stabilization** of the pelvis during gait; its dysfunction causes the unsupported side of the pelvis to drop. *Gluteus maximus* - The **gluteus maximus** is primarily involved in **hip extension** and external rotation, not hip abduction or pelvic stability during single-leg stance. - Weakness in this muscle would manifest more as difficulty with climbing stairs or rising from a seated position. *Quadriceps femoris* - The **quadriceps femoris** muscles are responsible for **knee extension**, essential for walking and standing. - Injury to these muscles would primarily affect the ability to **straighten the leg** and bear weight on it, not cause pelvic drop. *Quadratus lumborum* - The **quadratus lumborum** is a deep abdominal muscle involved in **lateral flexion of the trunk** and stabilization of the lumbar spine. - Dysfunction of this muscle would lead to **trunk instability** or pain, but not the specific pelvic drop seen in Trendelenburg's sign.

Question 9: The following gait is seen due to weakness of:

A. Gluteus maximus
B. Gluteus medius (Correct Answer)
C. Psoas major
D. Tibialis anterior

Explanation: ***Gluteus medius*** - Weakness of the **gluteus medius** leads to a **Trendelenburg gait**, where the pelvis drops on the unsupported side during the swing phase of gait. - The image suggests pelvic tilting, which is characteristic of the body attempting to compensate for the inability of the gluteus medius to stabilize the pelvis. *Gluteus maximus* - Weakness of the gluteus maximus causes difficulty in **hip extension**, resulting in a **lurching gait** where the trunk is thrown backward at heel strike. - This is commonly known as a **gluteus maximus lurch**, which is not depicted in an obvious manner here. *Psoas major* - Weakness of the psoas major would primarily affect **hip flexion**, making it difficult to lift the leg off the ground (e.g., during the swing phase). - This would result in compensatory movements such as circumduction or hiking the hip, rather than the characteristic pelvic drop. *Tibialis anterior* - Weakness of the tibialis anterior causes **foot drop**, leading to a **steppage gait** where the knee is lifted high to avoid dragging the foot. - The image does not show a foot drop or high stepping, thus ruling out tibialis anterior weakness.

Question 10: What is the best treatment for a 60-year-old man with intracapsular femoral neck fracture?

A. Hemiarthroplasty (Correct Answer)
B. Total hip replacement
C. Internal fixation
D. Casting

Explanation: **Hemiarthroplasty** * **Hemiarthroplasty** is generally preferred in older patients with **displaced intracapsular femoral neck fractures** due to the high risk of **avascular necrosis** and non-union with internal fixation. * In a 60-year-old, a hemiarthroplasty provides a good balance between **mobility** and avoiding the complexities of a total hip replacement, especially if the patient has lower functional demands or comorbidities. *Total hip replacement* * **Total hip replacement** might be considered for younger, more active patients with minimal comorbidities, or older patients with pre-existing **hip arthritis**, as it offers better long-term function and pain relief. * However, it's a more extensive procedure with a higher risk of complications like **dislocation** and necessitates careful selection based on the patient's physiological age and functional expectations. *Internal fixation* * **Internal fixation** is primarily used for **non-displaced** or minimally displaced intracapsular femoral neck fractures in active patients, or displaced fractures in younger patients (usually <60 years old) to preserve their native femoral head. * In a 60-year-old with a displaced fracture, the risk of **avascular necrosis** of the femoral head and **non-union** is significantly higher with internal fixation, making it a less preferred option. *Casting* * **Casting** is not an appropriate treatment for a femoral neck fracture. * Femoral neck fractures are **intra-articular** and require surgical stabilization to achieve stability and allow for early mobilization.

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