Limb Length Discrepancies — MCQs
At what age does the birth length double: UPSC 07; FMGE 10, 11
Genu valgus deformity seen when?
What is the condition commonly known as jumper's knee?
A child presented to an orthopaedic clinic with a limp. The surgeon suspected him to have a fixed flexion deformity of the hip. Which test should the surgeon perform to confirm his finding?
A radiograph is obtained from a child with scoliosis. What is the name of the angle used to measure spinal curvature?
All of the following can be the complications of a malunited Colles fracture except:
A 29-year-old man sustains a left femoral fracture in a motorcycle accident. His leg is placed in a plaster cast. After his left leg has been immobilized for 6 weeks, the diameter of the left calf has decreased in size. This change in size is most likely to result from which of the following alterations in his calf muscles?
Treatment of choice for a non-united fracture of the lower 1/4th of the tibia, characterized by multiple discharging sinuses and various puckered scars, with a 4cm shortening of the leg?
What condition is characterized by a waddling gait?
What is the characteristic upper limb deformity seen in Erb's palsy?
Limb Length Discrepancies Indian Medical PG Practice Questions and MCQs
Question 1: At what age does the birth length double: UPSC 07; FMGE 10, 11
- A. 1 year
- B. 4 years (Correct Answer)
- C. 3 years
- D. 2 years
Explanation: ***4 years*** - Birth length typically doubles by the age of **4 years**. - At birth, the average length is about 50 cm, so doubling means reaching approximately **100 cm** by 4 years of age. *1 year* - By 1 year of age, a child's birth length typically increases by about **50%**, reaching approximately 75 cm. - While significant growth occurs, it does not usually double the birth length. *3 years* - By 3 years of age, a child's height is usually around **90-95 cm**. - This is a substantial gain but generally still falls short of exactly doubling the birth length. *2 years* - At 2 years of age, a child's birth length is approximately **85-88 cm**. - This represents a significant increase, but it is not the age at which birth length typically doubles.
Question 2: Genu valgus deformity seen when?
- A. Long axis of tibia n fibula moves medial to long axis of femur
- B. Long axis of femur is anterior to tibia and fibula
- C. Long axis of femur is posterior to tibia and fibula
- D. Long axis of tibia n fibula moves lateral to the long axis of femur (Correct Answer)
Explanation: ***Long axis of tibia and fibula moves lateral to the long axis of femur*** - **Genu valgus**, also known as **knock-knees**, is a deformity where the knees angle inward, causing the lower legs to bow outward. - This alignment means the **long axis of the tibia and fibula (lower leg)** deviates laterally relative to the **long axis of the femur (thigh bone)**, bringing the knees closer together. *Long axis of tibia and fibula moves medial to long axis of femur* - This description corresponds to **genu varum**, or **bow-legs**, where the knees bow outward and the ankles are close together. - In genu varum, the lower leg bones deviate medially relative to the femur. *Long axis of femur is anterior to tibia and fibula* - This describes a sagittal plane misalignment, specifically relevant in cases of **knee hyperextension** or **recurvatum**, rather than typical genu valgus. - Genu valgus primarily involves coronal plane angulation at the knee. *Long axis of femur is posterior to tibia and fibula* - This anatomical relationship would imply a severe and unusual flexion deformity or dislocation, which is not characteristic of genu valgus. - Genu valgus involves a lateral deviation of the distal segment (tibia/fibula) in relation to the proximal segment (femur).
Question 3: What is the condition commonly known as jumper's knee?
- A. Inflammation of the patellar tendon at its insertion on the patella.
- B. Tendinopathy of the quadriceps tendon.
- C. Injury to the hamstring tendon.
- D. Patellar tendonitis due to overuse of the patellar tendon. (Correct Answer)
Explanation: ***Patellar tendonitis due to overuse of the patellar tendon.*** - **Jumper's knee** is the common term for **patellar tendonitis**, which specifically refers to inflammation of the patellar tendon. - This condition is frequently caused by **overuse**, especially in activities involving repetitive jumping and landing. *Inflammation of the patellar tendon at its insertion on the patella.* - While jumper's knee does involve inflammation of the patellar tendon, it is more commonly at its insertion on the **tibial tubercle** or specifically its origin at the **inferior pole of the patella**, not necessarily at the patella itself. - This option is less precise as it describes only one aspect of the condition without mentioning the critical role of overuse. *Tendinopathy of the quadriceps tendon.* - **Tendinopathy of the quadriceps tendon** is a distinct condition affecting the tendon above the patella, known as **quadriceps tendinopathy**. - It presents with pain proximal to the patella, differentiating it from jumper's knee, which involves the tendon distal to the patella. *Injury to the hamstring tendon.* - An **injury to the hamstring tendon** would cause pain and symptoms on the posterior aspect of the knee or thigh. - This is completely unrelated to jumper's knee, which is characterized by anterior knee pain.
Question 4: A child presented to an orthopaedic clinic with a limp. The surgeon suspected him to have a fixed flexion deformity of the hip. Which test should the surgeon perform to confirm his finding?
- A. Thomas test (Correct Answer)
- B. Trendelenburgs test
- C. Telescoping test
- D. Nelaton's test
Explanation: ***Thomas test*** - The **Thomas test** is specifically designed to detect a **fixed flexion deformity of the hip**, where the hip cannot fully extend. - During the test, the patient's hip is flexed to flatten the lumbar spine, and if the contralateral leg then rises off the table, it indicates a fixed flexion deformity. *Trendelenburg's test* - The **Trendelenburg's test** assesses the strength and function of the **hip abductor muscles**, primarily the gluteus medius. - A positive result indicates weakness of the abductors on the standing leg, causing the pelvis to drop on the unsupported side, which is unrelated to fixed flexion deformity. *Nelaton's test* - **Nelaton's test** is used to determine the relative position of the **greater trochanter** in relation to the **ischial tuberosity** and **anterior superior iliac spine (ASIS)**, primarily in cases of hip dislocation or fracture. - It would not specifically identify a fixed flexion deformity of the hip joint itself. *Telescoping test* - The **telescoping test** is used to evaluate for hip instability, particularly in infants with **developmental dysplasia of the hip (DDH)**. - It involves applying axial pressure to the femur while moving the hip, assessing for abnormal movement of the femoral head within the acetabulum, and does not directly detect fixed flexion deformity.
Question 5: A radiograph is obtained from a child with scoliosis. What is the name of the angle used to measure spinal curvature?
- A. Bohler's Angle
- B. Ferguson's Angle
- C. Cobb's Angle (Correct Answer)
- D. Pauwels' Angle
Explanation: **Cobb's Angle** - **Cobb's angle** is the primary method for measuring the severity of **scoliosis** on radiographs. - It is measured by drawing lines parallel to the superior endplate of the most tilted superior vertebra and the inferior endplate of the most tilted inferior vertebra of the curve; the angle between these two lines (or their perpendiculars) is the Cobb angle. *Bohler's Angle* - **Bohler's angle** is used in the assessment of **calcaneus fractures** and is measured on a lateral foot radiograph. - A decrease in this angle is indicative of a calcaneal fracture. *Ferguson's Angle* - **Ferguson's angle**, also known as the lumbosacral angle, measures the inclination of the sacrum relative to the horizontal in the standing position. - It is primarily used in the assessment of **spondylolisthesis** and other lumbosacral conditions. *Pauwels' Angle* - **Pauwels' angle** is used to classify **femoral neck fractures** based on the angle of the fracture line relative to the horizontal. - It helps determine the severity and stability of femoral neck fractures, guiding treatment decisions.
Question 6: All of the following can be the complications of a malunited Colles fracture except:
- A. Rupture of flexor pollicis longus tendon (Correct Answer)
- B. Carpal instability
- C. Carpal tunnel syndrome
- D. Reflex sympathetic dystrophy (RSD)
Explanation: ***Rupture of flexor pollicis longus tendon*** - Malunion of a Colles fracture typically involves dorsal displacement of the distal radius, which can lead to friction and rupture of the **extensor pollicis longus (EPL)** tendon due to irritation over the dorsal bony prominence. - The **flexor pollicis longus (FPL)** tendon is on the palmar side of the wrist and is generally not at risk for rupture from a dorsally malunited Colles fracture. *Carpal instability* - **Malunion of a Colles fracture** can significantly alter the normal anatomy and mechanics of the radiocarpal joint, leading to **carpal instability**. - Changes in radial inclination, volar tilt, and radial length can disrupt load bearing and ligamentous integrity, predisposing to carpal collapse or dissociation. *Carpal tunnel syndrome* - Malunion can lead to **decreased carpal tunnel volume** and angulation of the carpal bones, increasing pressure on the **median nerve**. - This anatomical alteration can lead to symptoms of **carpal tunnel syndrome**, such as numbness, tingling, and pain in the median nerve distribution. *Reflex sympathetic dystrophy (RSD)* - Also known as **Complex Regional Pain Syndrome (CRPS) Type I**, RSD is a well-recognized complication following trauma or surgery to an extremity, including Colles fractures. - It presents with pain, swelling, *trophic skin changes*, and vasomotor dysfunction, and can be severely incapacitating.
Question 7: A 29-year-old man sustains a left femoral fracture in a motorcycle accident. His leg is placed in a plaster cast. After his left leg has been immobilized for 6 weeks, the diameter of the left calf has decreased in size. This change in size is most likely to result from which of the following alterations in his calf muscles?
- A. Hyalinosis
- B. Dystrophy
- C. Aplasia
- D. Atrophy (Correct Answer)
Explanation: ***Atrophy*** - **Muscle atrophy** refers to the decrease in muscle mass due to disuse, denervation, or other pathological conditions [1]. In this case, prolonged **immobilization** of the leg in a cast leads to disuse of the calf muscles, resulting in a reduction in their size and strength [1]. - This process involves a decrease in the size of individual muscle cells and a reduction in the number of contractile proteins, such as **actin** and **myosin**, within these cells [1]. *Hyalinosis* - **Hyalinosis** is a process characterized by the accumulation of a glassy, homogeneous, eosinophilic material (hyaline) in tissues, often associated with degenerative changes. - It does not directly explain the specific reduction in muscle bulk due to immobilization; rather, it describes a type of degenerative change within cells or extracellular spaces. *Dystrophy* - **Muscular dystrophy** refers to a group of genetic diseases characterized by progressive weakness and degeneration of muscle fibers [2]. - It is a primary muscle disorder with a genetic basis, distinct from disuse-induced muscle wasting, and would not typically manifest as a result of temporary immobilization [2]. *Aplasia* - **Aplasia** is the failure of an organ or tissue to develop or to be completely formed. - This term is used to describe a congenital condition where a structure is completely absent or severely underdeveloped from birth, which is not applicable to a previously normal muscle decreasing in size after injury. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 90-91. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1244-1245.
Question 8: Treatment of choice for a non-united fracture of the lower 1/4th of the tibia, characterized by multiple discharging sinuses and various puckered scars, with a 4cm shortening of the leg?
- A. External fixator
- B. Plating
- C. Intramedullary nail
- D. Ilizarov's fixator (Correct Answer)
Explanation: ***Ilizarov's fixator*** - The presence of **multiple discharging sinuses** and **puckered scars** indicates chronic osteomyelitis, making bone transport and compression-distraction osteogenesis with an Ilizarov frame ideal. - The **4cm shortening** of the leg can be simultaneously corrected by limb lengthening through distraction osteogenesis using the Ilizarov technique. *External fixator* - While an external fixator can provide stability, a standard external fixator does not offer the same capabilities for **bone transport** or precise **limb lengthening** needed to address osteomyelitis and 4cm shortening simultaneously. - It would be less effective in managing the **infected non-union** and leg length discrepancy compared to an Ilizarov. *Plating* - **Plating** is generally contraindicated in cases of **active infection** (indicated by discharging sinuses) due to the high risk of further bacterial colonization of the implant and implant failure. - It would not address the **bone defect** or the **4cm shortening** effectively in an infected context. *Intramedullary nail* - **Intramedullary nailing** is absolutely contraindicated in the presence of **active infection** and discharging sinuses, as it would spread the infection throughout the medullary canal. - It also does not allow for **segmental bone resection** and subsequent limb lengthening to address both the infection and shortening.
Question 9: What condition is characterized by a waddling gait?
- A. Bilateral congenital dysplasia of hip (Correct Answer)
- B. Coxa valga
- C. CTEV
- D. Muscular dystrophy
Explanation: ***Bilateral congenital dysplasia of hip*** - A **waddling gait**, also known as a **Trendelenburg gait**, occurs due to weakness of the hip abductor muscles (gluteus medius and minimus) on both sides. - In bilateral congenital dysplasia of the hip, the **femoral heads are poorly seated** or dislocated, leading to ineffective abductor function and the characteristic gait. *Coxa valga* - This condition involves an **increased angle** between the femoral neck and shaft, which can alter biomechanics but does not typically cause a waddling gait in isolation. - While it can be associated with other hip pathologies, **coxa valga itself is not the primary cause** of a waddling gait. *CTEV* - **CTEV (Congenital Talipes Equinovarus)**, or **clubfoot**, is a deformity of the foot and ankle, not the hip. - It affects the patient's ability to walk normally, but results in a different type of gait abnormality, typically involving limping or walking on the outer edge of the foot, **not a waddling gait**. *Muscular dystrophy* - While many forms of muscular dystrophy can lead to a waddling gait due to **proximal muscle weakness**, it is a broad category of genetic disorders. - Without further context or specific type of muscular dystrophy, **bilateral congenital hip dysplasia is a more direct and specific cause** for the symptom described.
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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