NEET PG orthopaedics questions

Hard callus formation occurs roughly 2-6 weeks after fracture, when the soft fibrocartilaginous callus is progressively replaced by woven bone through endochondral and intramembranous ossification, producing clinical and radiological union with loss of fragment mobility. The fracture line may still be faintly visible on X-ray at this stage, but the bone is now rigid enough to bear load. This is followed by remodeling, in which woven bone is replaced by mature lamellar bone along stress lines over months to years. Soft callus, by contrast, is seen in the first 2-3 weeks and does not yet confer mechanical stability.

• A. Hematoma formation occurs in the first few days and consists of clotted blood and inflammatory cells, with no bridging bone.
• B. Remodeling occurs over months to years after union, converting woven bone to lamellar bone along lines of stress, not at 3 weeks.
• C. Soft callus occurs in the first 2-3 weeks and consists of fibrocartilage; fragments are still somewhat mobile.

Gustilo-Anderson grade II open fractures have a wound greater than 1 cm but less than 10 cm in length, with moderate soft tissue damage, mild to moderate crushing, and adequate bone coverage without extensive periosteal stripping. Grade I is reserved for wounds less than 1 cm, typically from a bone fragment piercing the skin from within. Grade III injuries involve extensive soft tissue damage, high-energy trauma, segmental fractures, or wounds over 10 cm, with further subdivision based on soft tissue coverage and vascular status. This classification guides the need for antibiotic prophylaxis duration, debridement urgency, and type of soft tissue coverage required.

• B. Grade IIIB involves extensive periosteal stripping and bone exposure requiring flap coverage, not present in this case.
• C. Grade IIIA involves extensive soft tissue damage or high-energy injury with adequate bone coverage, which is not described here.
• D. Grade I wounds are less than 1 cm, typically caused by an internal bony spike rather than external trauma of this size.

Fat embolism syndrome classically occurs 24-72 hours after long bone or pelvic fractures and presents with the triad of respiratory distress, neurological changes (confusion, agitation, or altered sensorium), and a petechial rash over the chest, axillae, and conjunctivae. It results from fat globules released from the marrow entering the venous circulation, causing mechanical obstruction and a biochemical inflammatory injury to pulmonary capillaries. Diagnosis is clinical, supported by hypoxemia and bilateral alveolar infiltrates on imaging resembling ARDS, and management is supportive with oxygenation and early fracture stabilization. The petechial rash, in particular, is a distinguishing feature not typically seen in pulmonary embolism or pneumonia.

• A. Pulmonary thromboembolism typically presents with pleuritic chest pain and sudden hypoxemia but does not classically cause a petechial rash.
• B. Pneumonia would typically show focal infiltrates with purulent sputum and lacks the petechial rash and temporal relationship to fracture seen here.
• C. Aspiration-related ARDS lacks the characteristic petechial rash and typically has a history of vomiting or decreased consciousness at the time of aspiration.

Pain disproportionate to the injury and pain worsened by passive stretching of the muscles within the compartment are the earliest and most sensitive clinical signs of compartment syndrome, preceding the classic late findings of pallor, pulselessness, and paralysis. The appropriate immediate step is to remove any constricting cast or dressing and directly measure intracompartmental pressure, since clinical suspicion with these early findings is sufficient to act even when distal pulses remain normal. Waiting for pulse loss or elevating the limb delays diagnosis and risks irreversible muscle and nerve ischemia within hours. Elevating the limb above heart level is actually contraindicated as it can further reduce perfusion pressure to the compartment.

• A. Elevating the limb reduces arterial perfusion pressure to the compartment and can worsen ischemia; it is not appropriate management.
• C. Doppler ultrasound assesses vessel patency but does not evaluate compartment pressure and is not the immediate priority here.
• D. Creatine kinase may be elevated in compartment syndrome but is a late, nonspecific marker and should not delay decompression.

Volkmann ischemic contracture results from forearm compartment syndrome following a supracondylar humeral fracture, usually due to brachial artery injury or compression, leading to ischemic necrosis of the flexor muscles, especially flexor digitorum profundus and flexor pollicis longus. The necrotic muscle is replaced by fibrous tissue, producing a fixed flexion deformity of the wrist and fingers with a claw-hand appearance. Early recognition of compartment syndrome with fasciotomy can prevent this complication; once established, treatment requires muscle slide procedures or tendon transfers. This is distinct from nerve palsies, which cause motor and sensory deficits without fixed fibrotic contracture at this early stage.

• A. Adhesive capsulitis affects shoulder joint mobility and is unrelated to forearm muscle ischemia or finger contracture.
• B. Cubitus varus is a bony malunion deformity affecting the elbow carrying angle, not a soft tissue flexion contracture of the fingers.
• C. Posterior interosseous nerve injury causes wrist drop and finger extension weakness, not a fixed flexion contracture from muscle fibrosis.

The AO principles of internal fixation are anatomical reduction of fracture fragments, stable internal fixation adequate to the functional demands, preservation of blood supply to the bone and soft tissues through atraumatic surgical technique, and early active pain-free mobilization of the limb and adjacent joints. These principles aim to restore both the anatomy and the function of the limb while minimizing complications like infection, nonunion, and stiffness. Preservation of blood supply emphasizes minimally invasive techniques and careful soft tissue handling rather than extensive stripping. Early mobilization reduces the risk of joint stiffness, muscle atrophy, and complications of prolonged immobilization such as deep vein thrombosis.

• A. Prolonged cast immobilization is a principle of conservative management, not of internal fixation under AO principles.
• C. Implant choice should match functional and biomechanical needs with minimal soft tissue disruption, not simply be the largest available.
• D. Excessive periosteal stripping devitalizes bone and increases infection and nonunion risk, contrary to AO principles of blood supply preservation.

A fall on an outstretched hand with the wrist extended produces a Colles fracture: an extra-articular fracture of the distal radius within 2-3 cm of the articular surface, with dorsal displacement and dorsal angulation of the distal fragment, plus radial shortening. The resulting silhouette, with the hand tilted up and back relative to the forearm, is classically described as a 'dinner fork' deformity. It is common in postmenopausal women with osteoporosis. Management is usually closed reduction and immobilization in a below-elbow cast with the wrist in flexion, pronation, and ulnar deviation.

• A. Isolated ulnar styloid fracture does not account for the dorsal displacement and dinner-fork appearance seen in this patient.
• B. Volar angulation with volar displacement describes a Smith fracture, which results from a fall on a flexed wrist, not an extended one.
• C. A scaphoid waist fracture does not produce the dorsal dinner-fork deformity described here.

The anterior interosseous nerve, a purely motor branch of the median nerve, is the nerve most commonly injured in extension-type supracondylar fractures of the humerus, particularly after closed reduction of a posteriorly displaced fragment. It supplies flexor pollicis longus and the flexor digitorum profundus to the index finger, so injury impairs flexion at the interphalangeal joints of the thumb and index finger, producing an inability to form the 'OK' sign, with no sensory loss since the nerve is purely motor. The median nerve overall is the most commonly injured nerve in supracondylar fractures, but the anterior interosseous branch is the specific pattern tested when the OK sign is affected. Most such palsies are neuropraxic and recover spontaneously over weeks to months.

• A. The posterior interosseous nerve is a motor branch of the radial nerve supplying forearm extensors and is not implicated in this presentation.
• B. Radial nerve injury causes wrist drop and sensory loss over the dorsum of the hand, not an isolated OK sign deficit.
• D. Ulnar nerve injury causes clawing of the ring and little fingers and weakness of intrinsic hand muscles, not loss of the OK sign.

A Monteggia fracture-dislocation consists of a fracture of the proximal third of the ulna combined with dislocation of the radial head, most commonly anterior dislocation following a direct blow or fall. It is explained by the 'nightstick' mechanism, where a direct blow to the ulna causes the fracture, and the attached annular ligament fails, allowing the radial head to dislocate. Prompt recognition is essential because missed radial head dislocation leads to poor functional outcomes; treatment in adults is open reduction and internal fixation of the ulna with closed or open reduction of the radial head. In children, closed reduction and casting often suffice if the ulna fracture is adequately reduced.

• A. Essex-Lopresti injury involves a radial head fracture with disruption of the interosseous membrane and distal radioulnar joint, not a proximal ulna fracture with radial head dislocation.
• C. Galeazzi fracture-dislocation involves a fracture of the distal radius with dislocation of the distal radioulnar joint, not the proximal ulna and radial head.
• D. Barton fracture is an intra-articular fracture-dislocation of the distal radius, unrelated to the proximal forearm.

A Galeazzi fracture-dislocation is a fracture of the distal third of the radial shaft associated with dislocation or subluxation of the distal radioulnar joint. It is sometimes called the 'fracture of necessity' because anatomical reduction, usually requiring open reduction and internal fixation in adults, is essential to restore forearm rotation and radioulnar joint stability. The injury typically results from a fall on an outstretched hand with forced pronation. Missed or inadequately reduced distal radioulnar joint disruption leads to chronic instability and painful restriction of pronation and supination.

• A. Colles fracture is an extra-articular distal radius fracture with dorsal displacement and does not involve the distal radioulnar joint dislocation described.
• B. Smith fracture involves volar displacement of the distal radius fragment, not a radial shaft fracture with distal radioulnar joint disruption.
• D. Monteggia fracture-dislocation affects the proximal ulna with radial head dislocation, the reverse level of injury described here.

Scaphoid fractures are notorious for being missed on initial radiographs because of overlapping bone and a non-displaced fracture line. Anatomical snuffbox tenderness with a positive axial thumb compression (scaphoid compression) test in the setting of a fall on an outstretched hand should raise strong suspicion despite normal initial films. The standard approach is to immobilize the wrist in a scaphoid (thumb spica) cast and repeat imaging, radiographs or MRI, after about 1-2 weeks when a fracture line becomes more visible or bone edema is detected. This caution is essential because the scaphoid's blood supply enters distally and runs retrograde, so missed or displaced fractures, especially of the proximal pole, carry a high risk of avascular necrosis and nonunion.

• A. Discharging the patient risks missing an occult fracture and progressing to avascular necrosis or nonunion.
• B. A bone scan may help but immobilization should not be withheld while awaiting further imaging in a clinically suspicious case.
• D. Surgery is not indicated empirically without confirmed fracture or displacement; initial management of suspected occult fracture is immobilization and repeat imaging.

The axillary nerve is the nerve most commonly injured in anterior shoulder dislocation because it winds closely around the surgical neck of the humerus after arising from the posterior cord. Injury produces weakness of deltoid-mediated abduction and a characteristic patch of sensory loss over the lower lateral deltoid, often called the regimental badge area, supplied by the superior lateral cutaneous nerve of the arm, a branch of the axillary nerve. Most such palsies are neuropraxic from stretch injury and recover spontaneously over several weeks, but sensory and motor testing of the axillary nerve should be documented before and after reduction. Persistent deficits beyond 3-6 months warrant further nerve conduction studies.

• B. Long thoracic nerve injury causes winging of the scapula due to serratus anterior weakness, not deltoid sensory or motor loss.
• C. Musculocutaneous nerve injury affects elbow flexion and forearm sensation, not shoulder abduction or the regimental badge area.
• D. Suprascapular nerve injury causes weakness of supraspinatus and infraspinatus without the characteristic deltoid sensory patch.

The radial nerve runs in close contact with the humeral shaft within the spiral (radial) groove, making it particularly vulnerable to injury in midshaft humeral fractures. Injury results in paralysis of the wrist and finger extensors, producing the classic wrist drop, along with sensory loss over the dorsal first web space supplied by the superficial radial nerve. Most radial nerve injuries associated with closed humeral shaft fractures are neuropraxic and resolve spontaneously within 3-4 months, so initial management is usually observation with a wrist splint unless the nerve is injured iatrogenically during fixation or the fracture is open.

• A. Median nerve injury causes loss of forearm pronation and thumb opposition with sensory loss over the palmar aspect of the lateral three and a half fingers, not wrist drop.
• B. Musculocutaneous nerve injury affects elbow flexion and lateral forearm sensation, not wrist and finger extension.
• C. Ulnar nerve injury causes clawing of the ring and little fingers, not wrist drop or first web space sensory loss.

In adults, the medial circumflex femoral artery (via its deep branch forming the retinacular vessels) supplies the majority of the femoral head's blood supply. A displaced femoral neck fracture disrupts these retinacular vessels, which run extracapsularly before piercing the capsule close to the femoral neck, leading to a high risk of avascular necrosis (AVN). The artery of the ligamentum teres contributes a minor supply that is clinically insufficient to prevent AVN in adults. The lateral circumflex femoral artery mainly supplies the vastus lateralis region and contributes little to the head.

• B. Contributes a minor, often insufficient, supply to the femoral head in adults.
• C. Mainly supplies the greater trochanter and lateral thigh muscles, not the femoral head.
• D. Supplies the acetabulum and medial thigh muscles, not the primary head supply.

The limb posture of flexion, adduction, and internal rotation with a dashboard injury mechanism is classic for posterior hip dislocation. The sciatic nerve, particularly its peroneal (common fibular) division, lies close to the posterior acetabular rim and is the nerve most commonly injured in this dislocation, producing foot drop with loss of dorsiflexion, toe extension, and dorsal foot sensation. Femoral nerve injury would cause quadriceps weakness and anterior thigh sensory loss, not seen here. Obturator and superior gluteal nerve injuries do not produce this pattern of foot drop.

• A. Superior gluteal nerve injury causes gluteus medius/minimus weakness with a Trendelenburg gait, not foot drop.
• B. Obturator nerve injury causes hip adductor weakness, not foot drop.
• C. Femoral nerve injury causes quadriceps weakness and anterior thigh numbness, not foot drop.

This presentation of disproportionate pain, pain on passive stretch, and a tense swollen leg after a tibial shaft fracture is classic for acute compartment syndrome, a surgical emergency. Intact distal pulses do not rule out compartment syndrome since arterial flow is often preserved until very late. The cast or any constrictive dressing should be immediately released, and intracompartmental pressure should be measured; a delta pressure (diastolic BP minus compartment pressure) less than 30 mmHg confirms the diagnosis and mandates emergency fasciotomy. Delaying treatment risks irreversible muscle and nerve ischemia.

• A. Opioids mask symptoms without addressing the underlying rising compartment pressure.
• C. Delaying definitive management risks irreversible muscle necrosis and permanent nerve damage.
• D. Simply reapplying a cast does not address or relieve the compartment pressure causing ischemia.

Fracture of the medial malleolus, lateral malleolus, and the posterior malleolus (posterior tibial margin) together constitutes a trimalleolar fracture, typically resulting from a rotational or supination-external rotation type ankle injury. This combination disrupts the ankle ring and syndesmosis, making the ankle grossly unstable; displaced trimalleolar fractures generally require open reduction and internal fixation to restore joint congruity and prevent post-traumatic arthritis. A bimalleolar fracture involves only two malleoli, and the described three-malleolus pattern with talar displacement is inherently unstable, not managed conservatively. Pilon fractures involve axial loading with comminution of the tibial plafond, a different mechanism, and Maisonneuve fracture involves a proximal fibular fracture with an intact distal fibula, not matching this presentation.

• B. Only two malleoli are described as fractured would be bimalleolar, and this pattern with three malleoli and talar shift is unstable, not stable.
• C. Pilon fractures result from axial compression with tibial plafond comminution, a different mechanism than described.
• D. Maisonneuve fracture involves a proximal fibular fracture with syndesmotic injury, not fracture of all three malleoli as described.

Calcaneal fractures classically result from axial loading after a fall from height, and the same compressive force is transmitted up the lower limb to the spine, commonly causing concurrent thoracolumbar (particularly T12-L2) compression or burst fractures. Because this association is well documented, every patient with a calcaneal fracture from a fall should have the thoracolumbar spine clinically and radiographically assessed, even in the absence of back pain, since it may be masked by heel pain. Cervical spine injury is more typical of flexion-extension mechanisms rather than pure axial loading from a fall onto the heels. Proximal humerus and pelvic fractures are not the classically associated injuries with this mechanism.

• A. Proximal humerus fracture is not the classic associated injury with a fall onto the heels.
• B. Cervical spine injury is more associated with flexion-extension mechanisms like diving or hyperextension injuries, not axial heel loading.
• C. Pelvic fracture is not the classic concurrent injury taught with calcaneal fractures from a fall from height.

Knee dislocation carries a high risk of popliteal artery injury because the artery is tethered proximally at the adductor hiatus and distally at the soleus arch, making it vulnerable to stretch or intimal tear during dislocation. Absent pulses and an abnormal ankle-brachial index after reduction indicate vascular compromise, which is a limb-threatening emergency requiring urgent vascular imaging (CT angiography) or surgical exploration and repair, since delayed revascularization beyond 6-8 hours significantly increases amputation risk. Conservative measures like elevation or anticoagulation alone do not address an arterial injury and risk limb loss from delay. Repeat radiography, while useful for assessing bony injury, does not take priority over addressing a limb-threatening vascular injury.

• A. Anticoagulation alone does not repair an arterial injury and risks limb loss from continued ischemia.
• B. This delays definitive diagnosis and treatment of a limb-threatening vascular injury, risking irreversible ischemia.
• C. Radiographic evaluation of bony alignment is not the priority when vascular compromise is evident.

In a hemodynamically unstable patient with an open-book pelvic fracture and a negative FAST, the most likely source of ongoing blood loss is the pelvic venous plexus or arterial branches within the retroperitoneal space. The immediate priority is mechanical reduction of pelvic volume with a pelvic binder or external fixator to reduce bleeding, followed promptly by angioembolization for arterial bleeding or definitive surgical stabilization, as per damage control principles in trauma. Exploratory laparotomy is not indicated since FAST is negative, meaning the bleeding is not predominantly intraperitoneal. Sending an unstable patient to CT for a prolonged scan delays life-saving hemorrhage control and risks cardiac arrest during transport.

• A. An unstable patient should not be transported for a prolonged CT scan before achieving hemorrhage control.
• C. Laparotomy is unnecessary since FAST is negative, indicating the hemorrhage is not predominantly intraperitoneal.
• D. Tranexamic acid may be adjunctive but does not replace mechanical hemorrhage control in unstable pelvic fracture.

A Jefferson fracture is a burst fracture of the atlas (C1) caused by axial loading, typically from a fall or diving injury where the force is transmitted vertically through the skull onto the lateral masses of C1, driving them outward and fracturing both the anterior and posterior arches. The transverse ligament may rupture, risking atlantoaxial instability. Diagnosis is confirmed by CT showing bilateral arch fractures with lateral mass displacement, best seen on open-mouth odontoid or axial CT views. Management depends on transverse ligament integrity, ranging from rigid collar immobilization to surgical fixation.

• A. Flexion with wedge compression affects the vertebral body of lower cervical vertebrae, not the ring-shaped atlas which lacks a body.
• C. Flexion-rotation injuries cause unilateral facet dislocations in the subaxial spine, not symmetric atlas burst fractures.
• D. Hyperextension injuries typically produce hangman's fractures or extension teardrop fractures, not a burst pattern of the atlas.

A hangman's fracture is a traumatic bilateral fracture through the pars interarticularis of the second cervical vertebra (C2), classically caused by forced hyperextension combined with axial loading, as seen in head-on collisions where the forehead strikes the windshield. The fracture allows the body of C2 along with C1 to translate anteriorly on C3. It was originally described in judicial hangings where the mechanism was distraction-extension. Management ranges from cervical orthosis for stable injuries to surgical fixation for unstable or severely angulated fractures.

• A. C6 is a subaxial level; pars interarticularis fractures with this specific mechanism and name are unique to C2.
• B. C1 fractures (Jefferson fracture) result from axial loading and involve the atlas, not the pars interarticularis fracture pattern described.
• C. C7 is a subaxial level and is not the site of the hangman's fracture pattern.

Cauda equina syndrome is a surgical emergency caused by compression of the lumbosacral nerve roots below the conus medullaris, presenting with bilateral leg pain, saddle anesthesia, bladder or bowel dysfunction (typically urinary retention with overflow incontinence), and reduced anal tone. Urgent MRI of the lumbosacral spine is the investigation of choice to confirm the diagnosis and localize the compressive lesion, most commonly a large central disc herniation. Surgical decompression should be performed as early as possible, ideally within 24-48 hours of symptom onset, since delay significantly worsens the chances of neurological recovery, particularly bladder and bowel function. Plain radiographs, steroids, or electrophysiological studies have no role in this time-critical emergency.

• A. Corticosteroids and outpatient referral are inappropriate for a surgical emergency requiring urgent decompression.
• C. Plain radiographs do not visualize soft tissue or nerve root compression, and delaying with bed rest risks permanent neurological deficit.
• D. Electrophysiological studies are time-consuming and not indicated in the acute emergent evaluation of suspected cauda equina syndrome.

The Ortolani test is performed by flexing the infant's hip to 90 degrees and gently abducting it while applying anterior pressure on the greater trochanter; a palpable or audible clunk indicates that a previously dislocated femoral head has been reduced into the acetabulum, confirming developmental dysplasia of the hip. In contrast, the Barlow test attempts to dislocate a reducible hip by adducting the flexed hip while applying posterior pressure. Both tests are most reliable in infants under 3 months of age, as capsular laxity decreases with age, after which ultrasonography or the Galeazzi sign become more useful. Breech presentation is a major risk factor for developmental dysplasia of the hip.

• A. The Barlow test is a provocative maneuver that dislocates an unstable hip rather than reducing an already dislocated one.
• B. The Trendelenburg test assesses hip abductor weakness in a standing or walking child, not neonatal hip stability.
• C. The Galeazzi sign compares knee heights with hips and knees flexed to detect limb length discrepancy, not a reduction clunk.

Slipped capital femoral epiphysis (SCFE) classically occurs in obese adolescent boys during the peripubertal growth spurt, presenting with hip or groin pain, limp, and a positive obligatory external rotation sign, in which the thigh rotates into external rotation as the hip is passively flexed, due to posterior and inferior displacement of the femoral epiphysis relative to the femoral neck through the weakened physis. Restricted internal rotation is a reliable clinical sign. Diagnosis is confirmed by anteroposterior and frog-leg lateral radiographs of the pelvis showing displacement of the epiphysis, often described using Klein's line. Perthes disease typically occurs in a younger age group of 4-8 years, and transient synovitis and septic arthritis present acutely rather than with a gradual three-week course.

• A. Septic arthritis presents acutely with fever, severe pain, and inability to bear weight, inconsistent with this three-week insidious course.
• B. Perthes disease occurs in a younger age group, typically 4-8 years, and is not associated with obesity or the obligatory external rotation sign described.
• C. Transient synovitis typically presents acutely over 1-2 days, often following a viral illness, without this characteristic rotational sign.

Legg-Calve-Perthes disease is idiopathic avascular necrosis of the proximal femoral epiphysis, occurring most commonly in children aged 4-8 years, more often boys, presenting with a painless or mildly painful limp. The exact etiology is unknown, but interruption of the blood supply to the femoral head leads to necrosis, followed by stages of fragmentation, reossification, and remodeling, radiographically seen as increased density, flattening, and later fragmentation of the femoral epiphysis. It is a self-limiting condition in most cases, but severe involvement can lead to femoral head deformity and early osteoarthritis if untreated. Management depends on age at onset and the degree of femoral head involvement, ranging from observation to containment surgery.

• A. Autoimmune synovitis describes juvenile idiopathic arthritis, which presents with joint swelling and systemic or polyarticular features, not isolated epiphyseal flattening.
• B. Epiphyseal slippage through the growth plate describes slipped capital femoral epiphysis, which occurs in older, typically obese adolescents.
• D. Septic arthritis causes rapid cartilage destruction with systemic signs of infection such as fever and raised inflammatory markers, which are absent here.

Congenital talipes equinovarus (clubfoot) is classically described using the mnemonic CAVE, comprising Cavus (high medial longitudinal arch due to forefoot pronation relative to the hindfoot), Adductus (forefoot deviated medially at the midtarsal joint), Varus (heel turned inward, inverted), and Equinus (ankle held in fixed plantarflexion due to tight Achilles tendon). These components together create the characteristic rigid foot deformity with a concave medial border seen at birth. Early recognition is essential, as the Ponseti method of serial manipulation and casting is the standard first-line treatment, typically started within the first few weeks of life.

• A. Abductus, valgus, and calcaneus describe deformities opposite in direction to clubfoot and are not components of this condition.
• C. Planus describes a flattened arch, which is the opposite of the cavus deformity seen in clubfoot, and calcaneus describes dorsiflexion, opposite to the equinus seen here.
• D. Abductus is incorrect; the forefoot in clubfoot is adducted, not abducted.

This is a classic presentation of a traction injury at the site where the patellar tendon inserts, occurring in adolescents during growth spurts who do repetitive jumping or running sports. Repeated traction causes microavulsion and reactive new bone formation at the tibial attachment, producing the clinical and radiographic picture described. It is self-limiting and managed conservatively with activity modification, stretching, and analgesia. The intact range of motion and absence of effusion exclude an intra-articular process.

• A. Osteochondritis dissecans affects the femoral condyle and presents with joint-line pain, locking, or effusion, not isolated tenderness over the shin.
• B. An avulsion fracture would follow acute trauma, not a 3-month gradual course, and would show a displaced bone fragment rather than irregular fragmentation at the apophysis.
• C. A ruptured tendon causes sudden pain with loss of active knee extension and a palpable gap, not a chronic activity-related ache with full motion.

The history of a longitudinal pull on a pronated, extended arm causing sudden pseudoparalysis without swelling or deformity is characteristic of subluxation of the annular ligament over the radial head. In a classic presentation with no signs of fracture, the diagnosis can be made clinically and treated immediately by manipulative reduction, either hyperpronation or supination followed by flexion, which is successful in most cases and gives instant relief of symptoms. Imaging is reserved for atypical presentations, suspected fracture, or failed reduction attempts.

• A. Routine imaging is unnecessary in a classic history and clinical picture and only delays reduction.
• B. There is no fracture or ligament disruption requiring immobilization; the condition resolves immediately with reduction.
• C. This is a benign, easily reducible condition that never requires surgery.

This is a typical presentation of acute hematogenous osteomyelitis localized to the metaphysis of a long bone, which is the usual site because of the sluggish blood flow in metaphyseal capillary loops favoring bacterial seeding. Staphylococcus aureus is the most common causative organism across all age groups including children, accounting for the large majority of cases. Early X-ray findings are often normal or show only soft tissue swelling, with bony changes appearing after 10 to 14 days. Treatment is empirical antistaphylococcal antibiotics pending blood and bone cultures.

• B. Salmonella is the characteristic organism in osteomyelitis complicating sickle cell disease, not in an otherwise healthy child.
• C. Tuberculous osteomyelitis has an indolent, chronic course over weeks to months, not an acute 4-day febrile presentation.
• D. Pseudomonas is classically associated with osteomyelitis following nail puncture wounds through footwear, not typical hematogenous spread.

In a child with clinical and sonographic features suggestive of septic arthritis of the hip, the most important immediate step is joint aspiration to obtain synovial fluid for cell count, Gram stain, and culture, which confirms the diagnosis and guides antibiotic choice. Prompt aspiration also serves a therapeutic purpose by decompressing the joint and reducing pressure-related cartilage and femoral head ischemia, particularly critical in the hip. Plain X-rays are often normal early and only show joint space widening or soft tissue changes. MRI is useful for detecting adjacent osteomyelitis but should not delay urgent aspiration and decompression.

• A. Plain X-ray is often normal in early septic arthritis and does not provide the microbiological confirmation needed to guide treatment.
• C. Starting antibiotics without aspiration denies the chance to isolate the organism and tailor therapy, and does not relieve the harmful intra-articular pressure.
• D. MRI is more useful for detecting associated osteomyelitis but takes longer to obtain and should not delay urgent joint decompression.

The Kocher criteria use four predictors to differentiate septic arthritis from transient synovitis in a child with an irritable hip: fever above 38.5°C, inability to bear weight, erythrocyte sedimentation rate above 40 mm/hr, and serum white cell count above 12,000/mm3. This child meets none of these criteria, being afebrile with normal inflammatory markers and partial weight-bearing ability, making transient synovitis, a benign self-limiting postviral synovial inflammation, the most likely diagnosis. Management is symptomatic with rest and anti-inflammatory analgesia, with review if symptoms worsen or fail to resolve.

• A. Avascular necrosis of the femoral head (Perthes disease) usually has an insidious onset over weeks and occurs in a slightly older age group, not an acute presentation following infection.
• B. Juvenile idiopathic arthritis typically presents with a more chronic course of joint swelling lasting weeks, not an acute 1-day limp after a viral illness.
• D. Septic arthritis would be expected to show high fever, inability to bear weight, and markedly elevated ESR and leukocyte count per Kocher criteria, none of which are present here.

Skeletal tuberculosis most commonly affects the spine, a condition known as Pott's disease, with the thoracic and thoracolumbar vertebrae being the most frequently involved sites due to their rich vascularity and weight-bearing stress. The infection typically begins in the anterior vertebral body adjacent to the disc, spreading beneath the anterior longitudinal ligament to involve adjacent vertebrae and the intervertebral disc, producing the classic radiographic finding of disc space narrowing with end plate destruction. Progressive vertebral body collapse leads to the characteristic kyphotic deformity (gibbus), and cord compression can cause neurological deficit if untreated.

• A. The sacroiliac joint can rarely be involved in skeletal tuberculosis but is far less common than spinal involvement.
• B. Small bones of the hand such as metacarpals can be affected in tuberculous dactylitis but this is a much rarer site compared to the spine.
• C. Long bone shaft involvement is uncommon in skeletal tuberculosis, which favors the vertebrae and large joints such as the hip and knee.

In chronic osteomyelitis, a sequestrum is a piece of necrotic, avascular bone that has separated from living bone, often acting as a nidus for persistent infection since it is impermeable to antibiotics and host defenses. The involucrum is the surrounding shell of new, living reactive bone laid down by the stripped periosteum in response to the infection, which encases the sequestrum. This combination is classic for chronic pyogenic osteomyelitis, commonly caused by Staphylococcus aureus. Surgical removal of the sequestrum (sequestrectomy) is usually necessary because it is a persistent source of infection unresponsive to antibiotics alone.

• A. Osteophyte and exostosis refer to bony outgrowths seen in degenerative joint disease, unrelated to chronic infection.
• C. Codman triangle and onion-skin periosteal reaction are radiological features of osteosarcoma and Ewing sarcoma, not chronic osteomyelitis.
• D. A Brodie abscess is a localized form of subacute osteomyelitis, and a cloaca is an opening through which pus drains, not the structures described.

Oral bisphosphonates are poorly absorbed and highly irritant to the esophageal mucosa, so remaining upright and taking the drug with a full glass of water on an empty stomach minimizes esophageal contact time and reduces the risk of esophagitis and esophageal ulceration. Bisphosphonates act by binding to hydroxyapatite in bone and inhibiting osteoclast-mediated bone resorption through inhibition of the mevalonate pathway in osteoclasts, thereby increasing bone mineral density. Osteonecrosis of the jaw and atypical femoral fractures are long-term complications related to oversuppression of bone turnover, not prevented by posture or timing of intake. Hypocalcemia can occur with potent intravenous bisphosphonates but is not related to the administration instructions given here.

• A. Atypical femoral fractures are associated with prolonged bisphosphonate use and altered bone remodeling, unrelated to administration technique.
• B. Hypocalcemia is a risk with potent intravenous bisphosphonates, not related to oral dosing instructions.
• D. Osteonecrosis of the jaw is a long-term complication related to oversuppressed bone turnover and invasive dental procedures, not prevented by positional counseling.

Osteosarcoma classically affects adolescents (10-20 years) at the metaphysis of long bones, most commonly the distal femur, followed by proximal tibia and proximal humerus. The periosteal elevation produces the Codman triangle, and perpendicular new bone spicules create the sunburst or sunray appearance. Night pain, a metaphyseal location, and this radiographic pattern in a teenager are classic for osteosarcoma. Diagnosis is confirmed by biopsy showing malignant osteoid production by tumor cells.

• A. Giant cell tumor occurs after epiphyseal fusion in young adults and is typically epiphyseal/subarticular, not metaphyseal with a sunburst sign.
• C. Osteomyelitis causes metaphyseal lysis and sequestrum but not a sunburst pattern with soft tissue radiating spicules.
• D. Ewing sarcoma occurs in a similar age group but typically arises in the diaphysis and shows onion-peel periosteal reaction rather than Codman triangle/sunburst.

Ewing sarcoma is a small round blue cell tumor of children and adolescents arising in the diaphysis of long bones, classically producing an onion-peel (lamellated) periosteal reaction on imaging. It is characterized by the t(11;22)(q24;q12) translocation, which fuses the EWSR1 and FLI1 genes to produce an aberrant transcription factor driving oncogenesis. Systemic features like fever and raised ESR mimicking infection are common, which can mislead toward a diagnosis of osteomyelitis. Immunohistochemistry typically shows strong CD99 positivity, supporting the diagnosis.

• A. t(8;14) MYC translocation is characteristic of Burkitt lymphoma.
• B. t(9;22) BCR-ABL is the Philadelphia chromosome, seen in chronic myeloid leukemia, not Ewing sarcoma.
• D. t(14;18) BCL2 is characteristic of follicular lymphoma.

Giant cell tumor of bone typically occurs in young adults aged 20-40 years, after epiphyseal closure, and characteristically involves the epiphysis extending to the subchondral bone, most often around the knee (distal femur or proximal tibia). Radiographically it appears as an eccentric, lytic, expansile lesion without a sclerotic rim, sometimes described as having a soap-bubble appearance. Histology shows multinucleated osteoclast-like giant cells on a background of mononuclear stromal cells. It is locally aggressive and can recur after curettage.

• A. Osteosarcoma occurs in a younger age group and is metaphyseal, not epiphyseal.
• B. Simple bone cysts are usually metaphyseal lesions in children and adolescents, not epiphyseal in adults.
• D. Chondroblastoma also occurs in the epiphysis but typically in a younger age group (10-20 years) and shows chondroid matrix calcification on histology.

Multiple myeloma presents with the classic CRAB features: hypercalcemia, renal insufficiency, anemia, and bone lesions, along with a monoclonal (M) spike on serum protein electrophoresis reflecting clonal plasma cell proliferation. The bone lesions are purely lytic, well-demarcated, punched-out areas without reactive sclerosis, typically seen in the skull, vertebrae, ribs, and pelvis. Elevated total protein with a normal-range albumin and a wide gap between total protein and albumin suggests a paraproteinemia. Bone marrow biopsy showing more than 10% clonal plasma cells confirms the diagnosis.

• A. Primary hyperparathyroidism causes subperiosteal bone resorption and brown tumors, not punched-out lytic lesions with an M spike.
• B. Paget disease shows mixed lytic-sclerotic lesions with cortical thickening, not punched-out lesions, and does not cause an M spike.
• C. Metastatic prostate carcinoma classically causes osteoblastic (sclerotic) lesions, not punched-out lytic lesions, and does not produce an M spike.

The most common primary tumors that metastasize to bone are, in order of frequency, carcinomas of the breast, lung, prostate, thyroid, and kidney. These tumors have a particular affinity for the axial skeleton, including the vertebrae, pelvis, ribs, and proximal long bones, due to the rich vascular supply of red marrow in these sites. Breast and prostate cancers together account for the largest proportion of skeletal metastases encountered clinically. The pattern of lesion (lytic, sclerotic, or mixed) can give a clue to the primary, for example, prostate causing sclerotic lesions and lung/kidney causing lytic lesions.

• A. Gastrointestinal carcinomas (colon, stomach, pancreas, esophagus) less commonly metastasize to bone compared with the listed group.
• B. Gynecological malignancies are not among the leading causes of skeletal metastasis.
• C. Genitourinary tumors other than prostate and kidney are not among the most common sources of bone metastasis.

Osteoarthritis is a degenerative joint disease characterized radiographically by asymmetric narrowing of the joint space (greatest in the area of maximal mechanical load), subchondral bony sclerosis, osteophyte formation at the joint margins, and subchondral cyst formation. These changes reflect progressive cartilage loss and reactive bone remodeling rather than an inflammatory synovial process. Clinically, pain worsens with use and improves with rest, and morning stiffness, if present, lasts less than 30 minutes, distinguishing it from inflammatory arthritis. Obesity and advancing age are major risk factors for knee osteoarthritis.

• A. Diffuse joint space widening with meniscal calcification suggests calcium pyrophosphate deposition disease (pseudogout/chondrocalcinosis), not typical osteoarthritis.
• C. Symmetric joint space narrowing with periarticular osteopenia and marginal erosions describes rheumatoid arthritis, an inflammatory arthropathy.
• D. Juxta-articular osteoporosis without osteophytes is typical of inflammatory arthritis, not osteoarthritis.

Rheumatoid arthritis is a symmetric inflammatory polyarthritis that characteristically involves the small joints of the hands, particularly the metacarpophalangeal and proximal interphalangeal joints, while sparing the distal interphalangeal joints. Chronic synovitis leads to characteristic deformities: ulnar deviation at the metacarpophalangeal joints, swan neck deformity (proximal interphalangeal hyperextension with distal interphalangeal flexion), and boutonniere deformity (proximal interphalangeal flexion with distal interphalangeal hyperextension). Prolonged morning stiffness lasting more than an hour reflects the inflammatory nature of the disease. Diagnosis is supported by positive rheumatoid factor and anti-cyclic citrullinated peptide antibodies along with radiographic erosions.

• B. Systemic lupus erythematosus can cause a nonerosive, reducible arthritis (Jaccoud arthropathy) but does not typically produce fixed swan neck or boutonniere deformities from erosive synovitis.
• C. Osteoarthritis typically involves the distal interphalangeal and first carpometacarpal joints with Heberden and Bouchard nodes, not swan neck or boutonniere deformities.
• D. Psoriatic arthritis can cause deforming arthritis but characteristically involves the distal interphalangeal joints and is associated with nail changes and psoriatic skin lesions.

Ankylosing spondylitis is a seronegative spondyloarthropathy strongly associated with HLA-B27, present in over 90% of affected patients. The radiographic appearance described, a continuous bridging syndesmophyte formation giving a smooth undulating outline to the spine, is the classic 'bamboo spine' sign, resulting from ossification of the annulus fibrosus and anterior longitudinal ligament. Sacroiliitis is typically the earliest radiographic finding, preceding spinal changes. The combination of inflammatory back pain, reduced chest expansion, and bamboo spine is diagnostic.

• A. HLA-B51 is associated with Behcet disease, not ankylosing spondylitis.
• C. HLA-DR3 is associated with conditions like type 1 diabetes and Sjogren syndrome.
• D. HLA-DR4 is associated with rheumatoid arthritis, not ankylosing spondylitis.

Avascular necrosis (AVN) of the femoral head should be suspected in patients on chronic corticosteroid therapy presenting with hip pain and limited internal rotation, even when radiographs are normal, since early-stage AVN precedes radiographic changes by months. MRI is the most sensitive and specific imaging modality for early AVN, showing a characteristic band-like or double-line sign on T2-weighted images due to marrow edema and the reactive interface. Early detection on MRI allows joint-preserving interventions such as core decompression before femoral head collapse occurs. Common causes of AVN include steroid use, alcoholism, trauma, sickle cell disease, and caisson disease.

• B. CT can show structural collapse in later stages but is less sensitive than MRI for early marrow changes.
• C. Bone scan can detect AVN earlier than radiographs but has lower sensitivity and specificity than MRI.
• D. Ultrasonography has no role in detecting femoral head avascular necrosis.

The sensory distribution involving the thumb, index, middle, and radial half of the ring finger, along with thenar wasting and weak thumb abduction, localizes to median nerve compression at the wrist, consistent with carpal tunnel syndrome. The positive response to tapping over the volar wrist, reproducing tingling in the median distribution, is Tinel's sign, a classic provocative test for carpal tunnel syndrome. Risk factors include repetitive wrist movements, pregnancy, hypothyroidism, and rheumatoid arthritis. Nerve conduction studies confirm the diagnosis, and treatment ranges from wrist splinting to surgical decompression of the flexor retinaculum.

• A. Ulnar nerve compression causes sensory loss over the little finger and ulnar half of the ring finger, not the thumb and index finger.
• B. Radial nerve compression causes wrist drop and sensory loss over the dorsum of the hand, not this palmar distribution.
• D. Anterior interosseous nerve is a purely motor branch and does not cause sensory symptoms.

This is De Quervain's tenosynovitis, a stenosing tenosynovitis of the first extensor compartment of the wrist involving the abductor pollicis longus and extensor pollicis brevis tendons. It commonly affects new mothers due to repetitive thumb and wrist movements while lifting an infant. The test described is Finkelstein's test, which is positive when ulnar deviation of the wrist with the thumb clasped in a fist reproduces sharp pain over the radial styloid. Treatment includes thumb spica splinting, NSAIDs, and corticosteroid injection, with surgical release reserved for refractory cases.

• B. Flexor pollicis longus and flexor digitorum superficialis are flexor tendons unrelated to the first dorsal compartment.
• C. Extensor pollicis longus lies in the third dorsal compartment, separate from the first compartment affected here.
• D. Extensor carpi radialis longus and brevis lie in a separate compartment and are not involved in De Quervain's disease.

The described posture, with the arm adducted, internally rotated, elbow extended, forearm pronated and wrist flexed, is the classic 'waiter's tip' posture of Erb's palsy, resulting from injury to the upper trunk of the brachial plexus involving the C5 and C6 nerve roots. This typically occurs due to excessive lateral traction on the head and neck during a difficult delivery with shoulder dystocia. The grasp reflex is preserved because the hand muscles, supplied by lower roots (C8, T1), are spared. In contrast, Klumpke's palsy involves C8 and T1 roots, producing a claw hand with intact shoulder movement but absent grasp reflex.

• A. C6 and C7 is not the standard root combination for either classic brachial plexus palsy pattern.
• C. C8 and T1 injury produces Klumpke's palsy with a claw hand and absent grasp reflex, not the waiter's tip posture.
• D. C7 and C8 is not the classic root combination described in either Erb's or Klumpke's palsy.

The finding described is a positive drop-arm test, which is most specific for a full-thickness tear of the supraspinatus tendon, the most commonly torn muscle of the rotator cuff. The supraspinatus initiates and assists abduction of the shoulder, and its tear leads to inability to actively maintain the abducted position, causing the arm to drop. Degenerative rotator cuff tears are common in older adults, particularly with repetitive overhead activity, due to the tendon's relatively poor vascular supply near its insertion. Supraspinatus tears are also assessed with the empty can (Jobe) test.

• B. Subscapularis tear weakens internal rotation and is assessed with the lift-off test, not the drop-arm test.
• C. Teres minor tear also affects external rotation and is rarely the isolated or most common rotator cuff tear.
• D. Infraspinatus tear primarily weakens external rotation and is tested with resisted external rotation, not the drop-arm test.

The common peroneal nerve winds around the neck of the fibula, where it is superficial and vulnerable to injury from fibular neck fractures, tight casts, or prolonged leg crossing. Injury here causes foot drop due to paralysis of the dorsiflexors and evertors (tibialis anterior, peroneus longus and brevis), producing a characteristic high-stepping gait to avoid dragging the toes. Sensory loss occurs over the dorsum of the foot and anterolateral leg, matching the nerve's cutaneous distribution. The ankle jerk reflex, mediated by the tibial nerve (S1-S2), remains normal since the tibial nerve is unaffected.

• A. Tibial nerve injury causes loss of plantarflexion and an absent ankle jerk, not foot drop with preserved ankle jerk.
• B. Sciatic nerve injury at the notch would affect both tibial and common peroneal distributions, including the ankle jerk, which is normal here.
• C. Femoral nerve injury affects hip flexion and knee extension, not foot dorsiflexion or eversion.

Plantar fasciitis is a clinical diagnosis based on start-up pain (worst with the first steps after rest) and point tenderness over the medial calcaneal tubercle, the origin of the plantar fascia. Passive dorsiflexion of the toes stretches the fascia and reproduces the pain, a useful bedside maneuver (windlass test). Obesity and prolonged standing are well-recognized risk factors due to repetitive microtrauma at the fascial origin. Imaging is not required for diagnosis; it is reserved for atypical or refractory cases.

• A. Achilles tendinopathy causes pain and tenderness along the posterior tendon above the heel, not at the plantar surface.
• B. Calcaneal stress fracture causes diffuse bony tenderness on squeezing the calcaneus from both sides, not localized tubercle tenderness with start-up pain.
• D. Tarsal tunnel syndrome causes burning pain and paresthesia along the medial ankle and sole with a positive Tinel sign over the tarsal tunnel, not isolated tubercle tenderness.