knee) — MCQs

10 questions

A 27-year-old man comes to the physician because of pain and swelling in his right knee that began 3 days ago when he fell during football practice. He fell on his flexed right knee as he dove to complete a pass. He felt some mild knee pain but continued to practice. Over the next 2 days, the pain worsened and the knee began to swell. Today, the patient has an antalgic gait. Examination shows a swollen and tender right knee; flexion is limited by pain. The right knee is flexed and pressure is applied to proximal tibia; 8 mm of backward translation of the foreleg is observed. Which of the following is most likely injured?

A 36-year-old male is taken to the emergency room after jumping from a building. Bilateral fractures to the femur were stabilized at the scene by emergency medical technicians. The patient is lucid upon questioning and his vitals are stable. Pain only at his hips was elicited. Cervical exam was not performed. What is the best imaging study for this patient?

A 47-year-old woman presents to the emergency department with pain in her right knee. She states that the pain started last night and rapidly worsened, prompting her presentation for care. The patient has a past medical history of rheumatoid arthritis and osteoarthritis. Her current medications include corticosteroids, infliximab, ibuprofen, and aspirin. The patient denies any recent trauma to the joint. Her temperature is 99.5°F (37.5°C), pulse is 112/min, blood pressure is 100/70 mmHg, respirations are 18/min, and oxygen saturation is 98% on room air. On physical exam, you note erythema and edema of the right knee. There is limited range of motion due to pain of the right knee. Which of the following is the best initial step in management?

An 18-year-old woman is brought to the emergency department by her coach, 30 minutes after injuring her left knee while playing field hockey. She was tackled from the left side and has been unable to bear weight on her left leg since the accident. She fears the left knee may be unstable upon standing. There is no personal or family history of serious illness. The patient appears uncomfortable. Vital signs are within normal limits. Examination shows a swollen and tender left knee; range of motion is limited by pain. The medial joint line is tender to touch. The patient's hip is slightly flexed and abducted, and the knee is slightly flexed while the patient is in the supine position. Gentle valgus stress is applied across the left knee and medial joint laxity is noted. The remainder of the examination shows no further abnormalities. Which of the following is the most likely diagnosis?

A 33-year-old man presents to his primary care physician for left-sided knee pain. The patient has a history of osteoarthritis but states that he has been unable to control his pain with escalating doses of ibuprofen and naproxen. His past medical history includes diabetes mellitus and hypertension. His temperature is 102.0°F (38.9°C), blood pressure is 167/108 mmHg, pulse is 100/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam reveals a warm and tender joint that is very tender to the touch and with passive range of motion. The patient declines a gait examination secondary to pain. Which of the following is the best next step in management?

A 24-year-old professional soccer player presents to the clinic with discomfort and pain while walking. He says that he has an unstable knee joint that started after an injury during a match last week. He adds that he heard a popping sound at the time of the injury. Physical examination of the knee reveals swelling of the knee joint with a positive anterior drawer test. Which of the following structures is most likely damaged in this patient?

A 25-year-old man comes to the emergency department with right knee pain. He was playing soccer when an opposing player tackled him from the side and they both fell down. He immediately heard a popping sound and felt severe pain in his right knee that prevented him from standing or walking. On physical examination, his right knee is swollen and there is local tenderness, mostly at the medial aspect. External rotation of the right knee elicits a significant sharp pain with a locking sensation. Which of the following structures is most likely injured?

A 25-year-old male presents to his primary care physician for pain in his knee. The patient was in a wrestling match when his legs were grabbed from behind and he was taken to the floor. The patient states that the moment this impact happened, he felt a snapping and sudden pain in his knee. When the match ended and he stood back up, his knee felt unstable. Minutes later, his knee was swollen and painful. Since then, the patient claims that he has felt unstable bearing weight on the leg. The patient has no significant past medical history, and is currently taking a multivitamin and protein supplements. On physical exam you note a tender right knee, with erythema and an effusion. Which of the following is the most likely physical exam finding in this patient?

A 25-year-old male wrestler presents to his primary care physician for knee pain. He was in a wrestling match yesterday when he was abruptly taken down. Since then, he has had pain in his left knee. The patient states that at times it feels as if his knee locks as he moves it. The patient has a past medical history of anabolic steroid abuse; however, he claims to no longer be using them. His current medications include NSAIDs as needed for minor injuries from participating in sports. On physical exam, you note medial joint tenderness of the patient’s left knee, as well as some erythema and bruising. The patient has an antalgic gait as you observe him walking. Passive range of motion reveals a subtle clicking of the joint. There is absent anterior displacement of the tibia relative to the femur on an anterior drawer test. The rest of the physical exam, including examination of the contralateral knee is within normal limits. Which of the following structures is most likely damaged in this patient?

Q10

A 25-year-old man comes to the physician because of left-sided knee pain for 2 weeks. The pain started while playing basketball after suddenly hearing a popping sound. He has been unable to run since this incident. He has asthma, allergic rhinitis, and had a progressive bilateral sensorineural hearing impairment at birth treated with cochlear implants. His only medication is a salbutamol inhaler. The patient appears healthy and well-nourished. His temperature is 37°C (98.6°F), pulse is 67/min, and blood pressure is 120/80 mm Hg. Examination of the left knee shows medial joint line tenderness. Total knee extension is not possible and a clicking sound is heard when the knee is extended. An x-ray of the left knee shows no abnormalities. Which of the following is the most appropriate next step in the management of this patient?

knee) US Medical PG Practice Questions and MCQs

Question 1: A 27-year-old man comes to the physician because of pain and swelling in his right knee that began 3 days ago when he fell during football practice. He fell on his flexed right knee as he dove to complete a pass. He felt some mild knee pain but continued to practice. Over the next 2 days, the pain worsened and the knee began to swell. Today, the patient has an antalgic gait. Examination shows a swollen and tender right knee; flexion is limited by pain. The right knee is flexed and pressure is applied to proximal tibia; 8 mm of backward translation of the foreleg is observed. Which of the following is most likely injured?

A. Posterior cruciate ligament (Correct Answer)
B. Anterior cruciate ligament
C. Medial collateral ligament
D. Lateral collateral ligament
E. Lateral meniscus

Explanation: ***Posterior cruciate ligament*** - The mechanism of injury, falling on a **flexed knee** with direct impact to the **proximal tibia**, is classic for a **posterior cruciate ligament (PCL)** injury. - The finding of **8 mm of backward translation** of the foreleg with pressure applied to the proximal tibia (positive **posterior drawer test**) is diagnostic for PCL injury. *Anterior cruciate ligament* - **Anterior cruciate ligament (ACL)** injuries typically result from sudden stopping, pivoting, or direct blows to the **front of the knee**, often causing **anterior translation** of the tibia. - The **anterior drawer test** or **Lachman test** would show increased anterior translation, not posterior. *Medial collateral ligament* - **Medial collateral ligament (MCL)** injuries usually occur due to a force applied to the **outside of the knee** (valgus stress), causing instability on the medial side. - Associated with tenderness over the medial knee joint line and instability with **valgus stress testing**. *Lateral collateral ligament* - **Lateral collateral ligament (LCL)** injuries typically result from a force applied to the **inside of the knee** (varus stress), leading to instability on the lateral aspect. - Associated with tenderness over the lateral knee joint line and instability with **varus stress testing**. *Lateral meniscus* - **Meniscal injuries** often present with mechanical symptoms such as clicking, locking, or catching, and pain that might worsen with specific movements like twisting or squatting. - While a fall could potentially injure the meniscus, the specific finding of **posterior tibial translation** points more directly to a ligamentous injury.

Question 2: A 36-year-old male is taken to the emergency room after jumping from a building. Bilateral fractures to the femur were stabilized at the scene by emergency medical technicians. The patient is lucid upon questioning and his vitals are stable. Pain only at his hips was elicited. Cervical exam was not performed. What is the best imaging study for this patient?

A. AP and lateral radiographs of hips
B. Lateral radiograph (x-ray) of hips
C. Magnetic resonance imaging (MRI) of hips, knees, lumbar, and cervical area
D. Anterior-posterior (AP) and lateral radiographs of hips, knees, lumbar, and cervical area
E. Computed tomography (CT) scan of cervical spine, hips, and lumbar area (Correct Answer)

Explanation: ***Computed tomography (CT) scan of cervical spine, hips, and lumbar area*** - In **high-energy trauma** (fall from height), a CT scan is the **gold standard** for evaluating the **spine and pelvis**, providing detailed cross-sectional images superior to plain radiographs. - Since the **cervical exam was not performed**, cervical spine imaging is **mandatory** per ATLS (Advanced Trauma Life Support) protocols. High-energy falls carry significant risk of **cervical spine injury** even without obvious neurological symptoms. - CT allows comprehensive assessment of **hip fractures, pelvic injuries, and the entire spine** (cervical, thoracic, lumbar), identifying both obvious and **subtle fractures** that may be missed on plain films. - This approach provides the most **efficient and thorough evaluation** in the acute trauma setting, allowing for appropriate surgical planning and ruling out life-threatening spinal instability. *AP and lateral radiographs of hips* - Plain radiographs provide **limited detail** and may **miss subtle fractures**, particularly in complex areas like the pelvis and acetabulum. - This option **fails to address cervical spine clearance**, which is essential in all high-energy trauma patients, especially when cervical exam has not been performed. - Radiographs are insufficient for **comprehensive trauma evaluation** after a fall from height. *Lateral radiograph (x-ray) of hips* - A single lateral view is **grossly insufficient** for evaluating hip and pelvic fractures, providing only a **two-dimensional perspective** that can miss significant injuries. - This option **completely neglects spinal evaluation**, which is dangerous in an uncleared trauma patient with a high-energy mechanism. *Magnetic resonance imaging (MRI) of hips, knees, lumbar, and cervical area* - While MRI excels at evaluating **soft tissues, ligaments, and bone marrow**, it is **not the initial imaging modality** for acute bony trauma due to longer scan times and lower sensitivity for acute fractures compared to CT. - MRI is **time-consuming and impractical** in the emergency setting for initial fracture assessment, potentially delaying definitive treatment. - CT is superior for evaluating **acute skeletal injuries** in the trauma bay. *Anterior-posterior (AP) and lateral radiographs of hips, knees, lumbar, and cervical area* - Multiple plain radiographs have **limited sensitivity** for complex or non-displaced fractures, particularly in the **spine and pelvis**, making them inadequate for high-energy trauma evaluation. - Obtaining multiple radiographic views requires **numerous patient repositionings**, which risks further injury if **spinal instability** is present. - Plain films provide significantly **less diagnostic information** than CT scanning for trauma assessment.

Question 3: A 47-year-old woman presents to the emergency department with pain in her right knee. She states that the pain started last night and rapidly worsened, prompting her presentation for care. The patient has a past medical history of rheumatoid arthritis and osteoarthritis. Her current medications include corticosteroids, infliximab, ibuprofen, and aspirin. The patient denies any recent trauma to the joint. Her temperature is 99.5°F (37.5°C), pulse is 112/min, blood pressure is 100/70 mmHg, respirations are 18/min, and oxygen saturation is 98% on room air. On physical exam, you note erythema and edema of the right knee. There is limited range of motion due to pain of the right knee. Which of the following is the best initial step in management?

A. Conservative therapy
B. Broad spectrum antibiotics
C. Surgical drainage
D. Aspiration (Correct Answer)
E. CT scan

Explanation: ***Aspiration*** - The patient's presentation with acute, severe **monoarticular arthritis**, especially in the context of **immunosuppressive medications** (corticosteroids, infliximab) and a history of rheumatoid arthritis (which increases the risk), strongly suggests **septic arthritis**. - **Joint aspiration** is the most crucial initial diagnostic and therapeutic step to confirm the diagnosis (via synovial fluid analysis for cell count, gram stain, culture) and guide subsequent treatment immediately. *Conservative therapy* - This approach, involving rest, ice, compression, and elevation, is generally insufficient and potentially harmful when an **infectious etiology** like septic arthritis is suspected. - Delaying definitive diagnosis and treatment for septic arthritis can lead to rapid **joint destruction** and systemic complications. *Broad spectrum antibiotics* - While antibiotics are critical for treating septic arthritis, they should be initiated **after joint aspiration** and Gram stain results to optimize treatment based on the most likely pathogen. - Administering antibiotics prior to aspiration may **sterilize the joint fluid**, making culture results unreliable and hindering pathogen identification. *Surgical drainage* - **Surgical drainage** is indicated for septic arthritis that does not respond to conservative aspiration and antibiotics, or if there are extensive loculations or involvement of prosthetic joints. - It is not the **initial step** in management for acute septic arthritis unless complications are already present or aspiration is unsuccessful. *CT scan* - A CT scan can assess **bone or soft tissue damage** or detect foreign bodies, but it is not the initial or most definitive diagnostic tool for septic arthritis. - **Arthrocentesis** (aspiration) is superior for diagnosing joint infection by directly analyzing synovial fluid.

Question 4: An 18-year-old woman is brought to the emergency department by her coach, 30 minutes after injuring her left knee while playing field hockey. She was tackled from the left side and has been unable to bear weight on her left leg since the accident. She fears the left knee may be unstable upon standing. There is no personal or family history of serious illness. The patient appears uncomfortable. Vital signs are within normal limits. Examination shows a swollen and tender left knee; range of motion is limited by pain. The medial joint line is tender to touch. The patient's hip is slightly flexed and abducted, and the knee is slightly flexed while the patient is in the supine position. Gentle valgus stress is applied across the left knee and medial joint laxity is noted. The remainder of the examination shows no further abnormalities. Which of the following is the most likely diagnosis?

A. Medial meniscus injury
B. Posterior cruciate ligament injury
C. Anterior cruciate ligament injury
D. Lateral collateral ligament injury
E. Medial collateral ligament injury (Correct Answer)

Explanation: ***Medial collateral ligament injury*** - The patient experienced a **valgus stress** injury (tackled from the left, forcing the knee inward) and presents with **medial joint line tenderness** and **medial joint laxity** upon valgus stress, all highly indicative of a medial collateral ligament (MCL) injury. - The MCL is a primary stabilizer against valgus forces, and its damage leads to instability and pain on the medial side of the knee. *Medial meniscus injury* - While a **meniscus injury** can cause swelling and pain, the primary finding of **medial joint laxity with valgus stress** points more directly to a ligamentous injury. - Meniscus injuries are often associated with mechanical symptoms like **locking or catching**, which are not described here. *Posterior cruciate ligament injury* - A **posterior cruciate ligament (PCL) injury** typically results from a direct blow to the **anterior tibia** or hyperflexion, which is not consistent with the mechanism of injury described ("tackled from the left side"). - PCL injuries are tested with a **posterior drawer test** or Sag sign, not valgus stress. *Anterior cruciate ligament injury* - An **anterior cruciate ligament (ACL) injury** usually occurs with a **twisting motion** or hyperextension, commonly associated with a "pop" sensation and rapid swelling due to hemarthrosis. - While the patient is unable to bear weight, the specific findings of **medial joint line tenderness** and **valgus laxity** are not primary indicators of an ACL tear. *Lateral collateral ligament injury* - A **lateral collateral ligament (LCL) injury** results from a **varus stress** (force from the inside pushing the knee outward), which is opposite to the mechanism of injury described. - LCL injuries would present with **lateral joint line tenderness** and laxity on varus stress.

Question 5: A 33-year-old man presents to his primary care physician for left-sided knee pain. The patient has a history of osteoarthritis but states that he has been unable to control his pain with escalating doses of ibuprofen and naproxen. His past medical history includes diabetes mellitus and hypertension. His temperature is 102.0°F (38.9°C), blood pressure is 167/108 mmHg, pulse is 100/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam reveals a warm and tender joint that is very tender to the touch and with passive range of motion. The patient declines a gait examination secondary to pain. Which of the following is the best next step in management?

A. Colchicine
B. Antibiotics
C. Arthrocentesis (Correct Answer)
D. IV steroids
E. Rest, elevation, and ice

Explanation: ***Arthrocentesis*** - The patient presents with unilateral, **acutely painful**, **warm**, and **tender joint** along with **fever**, suggesting a possible **septic joint**. - **Arthrocentesis** is the definitive diagnostic procedure to rule out **septic arthritis** by analyzing synovial fluid for cell count, culture, and crystal analysis. *Colchicine* - Colchicine is used to treat **gout flares**; however, a definitive diagnosis of gout requires **synovial fluid analysis** for crystals, and **septic arthritis** must be ruled out first. - The patient's presentation with **fever** and **unilateral warmth/tenderness** makes **septic arthritis** a critical concern that takes precedence over presumptive gout treatment. *Antibiotics* - While **septic arthritis** is highly suspected, initiating antibiotics without **synovial fluid culture** is premature and can compromise diagnostic accuracy. - **Arthrocentesis** is necessary to identify the causative organism and guide appropriate **antibiotic therapy**. *IV steroids* - **Systemic steroids** could potentially worsen an underlying **septic infection** by suppressing the immune response. - They are used in inflammatory arthropathies, but **septic arthritis** must be excluded before considering such treatment. *Rest, elevation, and ice* - These are supportive measures for joint pain but do not address the underlying cause of the patient's acute, febrile joint pain, especially the potential for **septic arthritis**. - Delaying proper diagnosis and treatment of a **septic joint** can lead to significant morbidity including **joint destruction** and **sepsis**.

Question 6: A 24-year-old professional soccer player presents to the clinic with discomfort and pain while walking. He says that he has an unstable knee joint that started after an injury during a match last week. He adds that he heard a popping sound at the time of the injury. Physical examination of the knee reveals swelling of the knee joint with a positive anterior drawer test. Which of the following structures is most likely damaged in this patient?

A. Lateral collateral ligament
B. Ligamentum patellae
C. Anterior cruciate ligament (Correct Answer)
D. Medial collateral ligament
E. Posterior cruciate ligament

Explanation: ***Anterior cruciate ligament*** - The **"popping sound"** at the time of injury, associated with knee **instability** and a **positive anterior drawer test**, are classic signs of an **ACL tear**. - The **anterior drawer test** specifically assesses the integrity of the ACL by checking for excessive anterior translation of the tibia relative to the femur. *Lateral collateral ligament* - Injury to the LCL typically results from a **varus stress** to the knee and is less commonly associated with a distinct "popping" sound or significant instability. - While it causes pain and instability, the **anterior drawer test** would likely be negative, and a **varus stress test** would be more indicative. *Ligamentum patellae* - Damage to the patellar ligament usually presents as pain and difficulty with knee extension, often following a forceful quadriceps contraction. - It does not typically cause the described popping sensation or knee instability assessed by the anterior drawer test. *Medial collateral ligament* - MCL injuries commonly result from a **valgus stress** (force to the outside of the knee) and are diagnosed with a **valgus stress test**, not the anterior drawer test. - While it can cause instability, the "popping" sound and specific findings of the anterior drawer test point away from an isolated MCL injury. *Posterior cruciate ligament* - A PCL injury is often associated with a **posteriorly directed force** to the tibia, such as a dashboard injury, and would present with a **positive posterior drawer test**. - The clinical presentation of a **positive anterior drawer test** and significant anterior instability rules out isolated PCL damage.

Question 7: A 25-year-old man comes to the emergency department with right knee pain. He was playing soccer when an opposing player tackled him from the side and they both fell down. He immediately heard a popping sound and felt severe pain in his right knee that prevented him from standing or walking. On physical examination, his right knee is swollen and there is local tenderness, mostly at the medial aspect. External rotation of the right knee elicits a significant sharp pain with a locking sensation. Which of the following structures is most likely injured?

A. Medial meniscus tear (Correct Answer)
B. Posterior cruciate ligament
C. Medial collateral ligament
D. Anterior cruciate ligament
E. Lateral meniscus tear

Explanation: ***Medial meniscus tear*** - The injury mechanism (tackle from the side) and symptoms (popping sound, severe pain, swelling, locking sensation, and pain on external rotation) are highly characteristic of a **meniscal tear**. - **Locking** and pain with specific rotational movements are classic signs of a meniscal injury, and the **medial meniscus** is more frequently injured due to its stronger attachment to the **medial collateral ligament** and less mobility. *Posterior cruciate ligament* - Injuries to the **PCL** typically result from direct trauma to the anterior aspect of the tibia with the knee flexed, or from hyperextension, neither of which is consistent with the described injury mechanism. - A torn PCL primarily causes posterior instability of the tibia, and a **locking sensation** is less common. *Medial collateral ligament* - An **MCL injury** is usually caused by a valgus stress (force from the side, pushing the knee inward), which could occur from a lateral tackle. - While it would cause pain and swelling, an isolated MCL injury does not typically present with a **popping sound**, **locking sensation**, or pain exacerbated by **external rotation** in the same manner as a meniscal tear. *Anterior cruciate ligament* - **ACL tears** commonly result from non-contact or contact injuries involving sudden deceleration, cutting, or jumping, often accompanied by a **popping sound**. - While it causes instability and swelling, an ACL tear generally does not present with a **mechanical locking sensation**; rather, patients often complain of feeling the knee "give way." *Lateral meniscus tear* - While a **lateral meniscus tear** can also cause popping, pain, and locking, the mechanism described (tackle from the side, implying a valgus force) typically puts more stress on the **medial aspect** of the knee. - Pain on **external rotation** is more indicative of a medial meniscal injury compared to a lateral one, which would more likely be aggravated by internal rotation.

Question 8: A 25-year-old male presents to his primary care physician for pain in his knee. The patient was in a wrestling match when his legs were grabbed from behind and he was taken to the floor. The patient states that the moment this impact happened, he felt a snapping and sudden pain in his knee. When the match ended and he stood back up, his knee felt unstable. Minutes later, his knee was swollen and painful. Since then, the patient claims that he has felt unstable bearing weight on the leg. The patient has no significant past medical history, and is currently taking a multivitamin and protein supplements. On physical exam you note a tender right knee, with erythema and an effusion. Which of the following is the most likely physical exam finding in this patient?

A. Laxity to valgus stress
B. Anterior translation of the tibia relative to the femur (Correct Answer)
C. Clicking and locking of the joint with motion
D. Laxity to varus stress
E. Posterior translation of the tibia relative to the femur

Explanation: ***Anterior translation of the tibia relative to the femur*** - The rapid onset of a "snapping" sensation, immediate swelling, and instability after a traumatic event involving twisting or hyperextension of the knee is highly suggestive of an **anterior cruciate ligament (ACL) tear**. - A torn ACL allows for excessive **anterior translation** of the tibia relative to the femur, which is assessed clinically with tests like the **Lachman test** or **anterior drawer test**. *Laxity to valgus stress* - **Laxity to valgus stress** indicates injury to the **medial collateral ligament (MCL)**. While MCL tears can occur with ACL tears, the mechanism described (legs grabbed from behind, taken to the floor, resulting in instability) more directly points to an ACL injury rather than primarily an MCL tear, which often results from a direct blow to the lateral knee. - The patient's primary complaint of a single "snapping" event followed by instability is more characteristic of an ACL tear than an isolated MCL injury. *Clicking and locking of the joint with motion* - **Clicking and locking** of the joint are classic signs of a **meniscal tear**, which can accompany ACL injuries but are not the primary or most likely *initial* physical exam finding for an acute ACL tear. - While instability is also present in meniscal tears, the immediate swelling and "snapping" described are more characteristic of ligamentous damage. *Laxity to varus stress* - **Laxity to varus stress** indicates injury to the **lateral collateral ligament (LCL)**, which is much less common than ACL or MCL tears and typically results from a varus force applied to the knee. - The mechanism described (being taken to the floor from behind) does not strongly suggest an LCL injury as the primary lesion. *Posterior translation of the tibia relative to the femur* - **Posterior translation of the tibia relative to the femur** is indicative of a **posterior cruciate ligament (PCL) tear**, which usually results from a direct blow to the anterior tibia when the knee is flexed (dashboard injury) or a fall onto a flexed knee. - The mechanism of injury in this patient (legs grabbed from behind, twisting/hyperextension) is not typical for a PCL injury.

Question 9: A 25-year-old male wrestler presents to his primary care physician for knee pain. He was in a wrestling match yesterday when he was abruptly taken down. Since then, he has had pain in his left knee. The patient states that at times it feels as if his knee locks as he moves it. The patient has a past medical history of anabolic steroid abuse; however, he claims to no longer be using them. His current medications include NSAIDs as needed for minor injuries from participating in sports. On physical exam, you note medial joint tenderness of the patient’s left knee, as well as some erythema and bruising. The patient has an antalgic gait as you observe him walking. Passive range of motion reveals a subtle clicking of the joint. There is absent anterior displacement of the tibia relative to the femur on an anterior drawer test. The rest of the physical exam, including examination of the contralateral knee is within normal limits. Which of the following structures is most likely damaged in this patient?

A. Lateral meniscus
B. Lateral collateral ligament
C. Anterior cruciate ligament
D. Medial collateral ligament
E. Medial meniscus (Correct Answer)

Explanation: ***Medial meniscus*** - The patient's history of knee trauma during a wrestling match, followed by **locking** and **clicking** sensations, is highly indicative of a meniscal tear. - **Medial joint line tenderness** specifically points towards involvement of the medial meniscus, which is more commonly injured than the lateral meniscus. *Lateral meniscus* - While a meniscal tear is likely, the presence of **medial joint tenderness** makes a lateral meniscus tear less probable. - A lateral meniscus tear would typically present with pain localized to the **lateral aspect** of the knee. *Lateral collateral ligament* - Injury to the LCL typically results from a **varus stress** to the knee, often causing pain on the lateral side and instability, which are not primary complaints here. - The physical exam did not describe any instability on **varus stress testing**, making an isolated LCL injury less likely. *Anterior cruciate ligament* - ACL injuries usually involve a distinct "pop" sensation and **knee instability**, particularly during activities requiring pivoting or cutting. - The **absent anterior displacement** on the anterior drawer test effectively rules out an acute ACL tear. *Medial collateral ligament* - MCL injuries result from a **valgus stress** to the knee, causing pain and tenderness along the medial aspect of the knee and often **instability** during valgus stress testing. - While there is medial tenderness, the presence of **locking and clicking** strongly points towards a meniscal injury rather than an isolated ligamentous injury, and significant instability is not described.

Question 10: A 25-year-old man comes to the physician because of left-sided knee pain for 2 weeks. The pain started while playing basketball after suddenly hearing a popping sound. He has been unable to run since this incident. He has asthma, allergic rhinitis, and had a progressive bilateral sensorineural hearing impairment at birth treated with cochlear implants. His only medication is a salbutamol inhaler. The patient appears healthy and well-nourished. His temperature is 37°C (98.6°F), pulse is 67/min, and blood pressure is 120/80 mm Hg. Examination of the left knee shows medial joint line tenderness. Total knee extension is not possible and a clicking sound is heard when the knee is extended. An x-ray of the left knee shows no abnormalities. Which of the following is the most appropriate next step in the management of this patient?

A. Reassurance and follow-up
B. Arthrocentesis of the left knee
C. Open meniscal repair
D. Arthroscopy of the left knee
E. MRI scan of the left knee (Correct Answer)

Explanation: ***MRI scan of the left knee*** - The patient's presentation with a **popping sound**, inability to run, **medial joint line tenderness**, limited extension, and a clicking sound suggests a **meniscal tear**, which is not visible on X-ray. - An **MRI scan** is the *most appropriate* next step as it is the **gold standard** for diagnosing meniscal tears and other soft tissue injuries of the knee. *Reassurance and follow-up* - This option is *inappropriate* given the clear signs and symptoms of a **significant knee injury** that warrants further investigation. - Delaying diagnosis and treatment could lead to **worsening of the injury** and chronic pain. *Arthrocentesis of the left knee* - Arthrocentesis involves aspirating joint fluid, which is primarily indicated for diagnosing **septic arthritis** or **gout**, neither of which is suggested by this patient's acute trauma history. - While a meniscal tear can cause an effusion, the primary diagnostic goal here is imaging the soft tissue injury, not analyzing synovial fluid. *Open meniscal repair* - **Open meniscal repair** is a surgical intervention, and it is *premature* to consider surgery before a definitive diagnosis is established. - The *most appropriate* initial step after physical exam and X-ray is often an MRI to confirm the pathology. *Arthroscopy of the left knee* - **Arthroscopy** is both a **diagnostic and therapeutic procedure**, but it is generally reserved after non-invasive imaging like MRI has been performed. - Although it can confirm a meniscal tear, an MRI is less invasive and can provide comparable if not superior detail for surgical planning.

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