Question 1

A 72-year-old woman who smokes 5â€“10 cigarettes per day and has a past history of whooping cough presents with chronic cough and recurrent chest infections for review. She admits to producing frequent amounts of purulent sputum and of intermittently suffering night sweats for a number of months. There have also been occasional episodes of haemoptysis. Chest X-ray reveals hyperinflation, crowded lung markings and small, cyst- like spaces at the lung bases. What is the most likely underlying pathology?

Explanation

Correct Answer: C- Bronchiectasis Explanation Bronchiectasis The past history of whooping cough and smoking, coupled with the X-ray changes, are very suggestive of bronchiectasis. Non-pharmacological management involves self-physiotherapy and adequate hydration. Chronic intermittent oral antibiotic therapy is used by some physicians, although it might encourage the development of multi-drug resistance and its use is not universally endorsed. Influenza and pneumococcal vaccinations are strongly recommended. Surgical referral might be recommended for patients with chronic severe localised infection that fails to resolve after intravenous antibiotic therapy. Asthma Asthma is incorrect. The predominant symptom of asthma is wheeze, which is not mentioned here. Asthma is not associated with chronic productive cough, haemoptysis or night sweats. Bronchial carcinoma Bronchial carcinoma is incorrect. Bronchial carcinoma causing a lobar airway obstruction and subsequent recurrent infectons is a reasonable differential here. However, the history of whooping cough and the chest radiograph appearances point more towards a diagnosis of bronchiectasis. Chronic lung abscess Chronic lung abscess is incorrect. A chronic lung abscess would be seen on the chest radiograph. The chest radiograph appearances described in this case are most consistent with bronchiectasis. Tuberculosis Tuberculosis is incorrect. The duration of symptoms coupled with the history of whooping cough and chest radiograph appearances are more consistent with bronchiectasis. In tuberculosis, you would expect a shorter duration of symptoms before presentation and chest X-ray would typically show upper lobe consolidation +/- lymphadenopathy.

Question 2

A 71-year-old man comes to the Respiratory Clinic for review. He has a history of chronic obstructive pulmonary disease (COPD) managed with high-dose Seretide and tiotropium, and right heart failure for which he takes ramipril and bumetanide. He has an exercise tolerance of 80 m and has had two COPD exacerbations in the past year. On examination his BP is 135/85 mmHg; pulse is 75/min and regular. Auscultation reveals bilateral poor air entry and wheeze. He has bilateral pitting oedema to just above the ankles. His BMI is 23.

Investigations:

Hb 13.8 g/dl

WCC 9.3 Ã— 109/l

PLT 189 Ã— 109/l

Na+ 138 mmol/l

K+ 4.3 mmol/l

Bicarbonate 32 mmol/l

Creatinine 122 μmol/l

pH 7.44

pO2 7.8 kPa (7.7 kPa 3 months earlier)

pCO2 6.5 kPa Which of the following is the most important argumentation justifying prescription of long- term oxygen therapy (LTOT) in this patient?

Explanation

Correct Answer: C- pO2 7.8 kPa and right heart failure Explanation

pO2 7.8 kPa and right heart failure O2 is the main driver for LTOT prescription. Guidelines state that LTOT should be offered to patients with PaO2 less than 7.3 kPa when stable, or greater than 7.3 kPa and less than 8 kPa when stable, who also have secondary polycythaemia, peripheral oedema, nocturnal hypoxaemia or pulmonary hypertension. CO2 retention is a driver for pulmonary hypertension, and the presence of right heart failure allows the less stringent threshold for O2 prescription to be used, as here. Exercise tolerance 80 m Exercise tolerance 80 m is incorrect. Although exercise tolerance is associated with poorer prognosis, it is not a driver for oxygen prescription.

pCO2 6.5 kPa and right heart failure

pCO2 6.5 kPa and right heart failure is incorrect. It is the degree of hypoxia, not hypercapneoa that dictates the need for long-term oxygen therapy. Presence of right heart failure irrespective of pO2 Presence of right heart failure irrespective of pO2 is incorrect. LTOT only confers a survival benefit in patients with right heart failure with a pO2 < 8 kPa when stable. It would therefore be inappropriate to prescribe LTOT in a patient with a pO2 greater than this, even in the presence of heart failure. Two exacerbations in the past year Two exacerbations in the past year is incorrect. Although increased exacerbations are associated with poorer prognosis, they are not a driver for oxygen prescription.

Question 3

A 52-year-old patient from a chemical factory presents with cough and is found to have a squamous lung carcinoma. He is quite sure that it is work related. He smoked five cigarettes per day until he was aged 34, having started smoking at the age of 16. What is the most likely cause?

Explanation

Correct Answer: C- Isocyanates Explanation Isocyanates Isocyanates are a recognised risk factor for the development of non-small-cell lung cancer. Other aetiological factors include smoking, asbestos exposure and exposure to polycyclic hydrocarbons or the products of coal burning. Exposure to isocyanate fumes occurs in chemical workers, particularly those who work in the rubber industry, and this exposure is most likely to be associated with squamous-cell carcinoma of the bronchus. Most squamous-cell carcinomas present as obstructive lesions, which can manifest as infection. Around 10% of cases present with cavitating lesions, but widespread metastases occur relatively late. Aromatic amines Aromatic amines is incorrect. Aromatic amines are associated with bladder carcinoma. Coal dust Coal dust is incorrect. There is nothing in the history to suggest coal dust exposure. Polyvinyl chloride Polyvinyl chloride is incorrect. Exposure to vinyl chloride is associated with angiosarcoma of the liver. Smoking Smoking is incorrect. He has a relatively low smoking exposure in terms of patient years; as such, it is isocyanates which are likely to have had a larger impact on his lung cancer risk.

Question 4

A 32-year-old black woman presents with a 3-month history of a non-productive cough, dyspnoea and pleuritic chest pain, especially on climbing stairs. She reports intermittent fevers of up to 39 °C and a 3.5-kg weight loss. She complains of wrist and ankle pain that has interfered with her work. She smokes two packets of cigarettes per day. Her full blood count is normal and her serum antinuclear antibody (ANA) is negative. On examination there are red nodules over her lower legs. What is the most likely diagnosis?

Explanation

Correct Answer: D- Sarcoidosis Explanation Sarcoidosis Sarcoidosis is most common in black women, but the aetiology is unknown. It is characterised by the presence of non-caseating granulomas in at least two organs. Pulmonary involvement has been described in more than 90% of patients and the lymph nodes and the lung parenchyma can both be involved. Clinical manifestations include:

• Dry cough • Dyspnoea • Arthralgias • Erythema nodosum • Systemic symptoms, including:

• Fever • Weight loss • Fatigue Adenocarcinoma of the lung Adenocarcinoma of the lung is incorrect. Malignancy would be a differential diagnosis however, the presence of intermittent fevers, arthralgia and rash suggestive of erythema nodosum is more consistent with sarcoidosis. Patients with adenocarcinomas are often non-smokers. Goodpasture syndrome Goodpasture syndrome is incorrect. Goodpasture syndrome is associated with pulmonary haemorrhage and renal impairment with nephritis which are not described here therefore, this diagnosis is unlikely. Histoplasmosis Histoplasmosis is incorrect. Histoplasmosis is a fungal infection which, in severe infections, can be associated with fever, headace, myalgia, dry cough, chest pain, arthralgia, rash and weight loss – all of which are described in this case. However, there is nothing mentioned in the history to suggest risk factor for histoplasmosis. There is no history of immunosuppression and there is no mention of a potential risk factor (e.g. farming, poultry keeping, construction work, roofing, gardening). Sarcoidosis is more likely here. Systemic lupus erythematosus Systemic lupus erythematosus is incorrect. Systemic lupus erythematosus is also a reasonable differential diagnosis however the lack of cytopenias, negative ANA and rash suggestive of erythema nodosum means sarcoidosis is more likely.

Question 5

An 81-year-old woman who had consulted her GP with symptoms of flu 2 weeks earlier now presents to the Emergency Department. For the past few days she has had increasing cough, associated with purulent sputum and haemoptysis. Her daughter visited and noticed that she had become acutely confused and arranged an ambulance. On arrival to the department she is found to be agitated, with a respiratory rate of 35/min. Blood gases reveal that she is hypoxic, her white blood cell count is 20 — 109/l, predominantly neutrophils. Her creatinine concentration is 250 Âµmol/l. Chest X-ray reveals patchy areas of consolidation, with necrosis and empyema formation. What diagnosis best fits this clinical picture?

Explanation

Correct Answer: D- Staphylococcus aureus pneumonia Explanation Staphylococcus aureus pneumonia In general, staphylococcal pneumonia only occurs after a preceding viral illness. Patchy areas of consolidation occur that eventually break down into abscesses. Pneumothorax, pleural effusion and empyema are common in staphylococcal pneumonia. Clinical features of severe pneumonia include a respiratory rate > 30/min, diastolic blood pressure < 60 mmHg, confusion, involvement of more than one lobe, low albumin concentration, white cell count > 20 × 109/l or less than 1 × 109/l, and renal dysfunction. Treatment: fulminant staphylococcal pneumonia, as in this case, carries a high mortality. Standard therapy would be intravenous cefuroxime and clarithromycin, with added flucloxacillin for suspected Staphylococcus aureuspneumonia. Chlamydia psittaci pneumonia Chlamydia psittaci pneumonia is incorrect. Chlamydia psittaci pneumonia was originally described in people who kept the psittacine family of birds (eg parrots). The peak age at presentation is 30–60 years and it has an equal sex distribution. Mortality is low (0.7%). The incubation period is 1–2 weeks, but the illness can follow a protracted course over a number of months. Symptoms usually include increasing tiredness, high fevers at night, cough and myalgia, and liver function tests might show mild abnormalities in up to 50%. The chest X-ray can show segmental or diffuse consolidation. Diagnosis is confirmed by enzyme immunoassay. Treatment is with macrolide or tetracycline antibiotics. Haemophilus influenzae pneumonia Haemophilus influenzae pneumonia is incorrect. Haemophilus influenzae pneumonia produces classical symptoms of pneumonia with cough, fever and shortness of breath. Most patients will have significant underlying comorbidities such as alcohol dependence, chronic obstructive pulmonary disease (COPD), or diabetes mellitus. The overall mortality rate for adults is high at 30–60% and is probably related to the severe comorbid conditions affected patients tend to have along with the pneumonia itself. Complications can include lung abscess, empyema, meningitis, arthritis, pericarditis, epiglottitis, and, in children, otitis media. The fact that this lady had symptoms of influenza preceding the illness makes staphylococcal pneumonia more likely. In addition, although Haemophilus influenzae pneumonia can lead to lung abscesses and empyema, these are more commonly seen with staphylococcal pneumonias. Mycoplasma pneumonia Mycoplasma pneumonia is incorrect. Mycoplasmal infections occur in epidemics every 4–5 years, more commonly among close-knit populations such as those in schools and colleges. Mycoplasmal infection is not associated with exposure to birds. The peak age of presentation of mycoplasmal pneumonia is 5–20 years, and Mycoplasma pneumonia accounts for about 7% of all community- acquired pneumonias. Cold agglutinins are associated in up to 50% of cases and muscle tenderness is reported to occur in up to 50%. The X-ray appearances are usually much worse than would be suggested by the clinical examination of the respiratory system. Treatment consists of a 2-week course of erythromycin or clarithromycin. X-ray resolution is complete by week 8 in around 90% of patients. Streptococcus pneumoniae pneumonia Streptococcus pneumoniae pneumonia is incorrect. Streptococcus pneumoniae is the most common cause of community-acquired pneumonia and produces classical symptoms such as cough, fever, dyspnoea and malaise. The most common complication is pleural effusion, which can progress to empyema in severe cases. Herpetic ulcers often predate the development of symptoms but are not mentioned in this case. Although a viral illness can precede a streptococcal pneumonia, a history suggestive of recent influenza is most classically associated with staphylococcal pneumonia, making pneumonia secondary to Staphylococcus aureus more likely.

Question 6

A 50-year-old retired boilermaker with shortness of breath comes to the Respiratory Clinic. He has smoked ten cigarettes per day for the past 30 years. The GP wonders if he has obstructive lung disease and the man arrives with his spirometry results, which show: forced expiratory volume in 1 s (FEV1) 1.74 l (predicted 3.0 l), forced vital capacity (FVC) 2.5 l (predicted 2.8 l); post- salbutamol

FEV1 1.81 l, post-salbutamol FVC 2.7 l; transfer factor 55%. Which of the following is the most likely diagnosis?

Explanation

Correct Answer: C- Emphysema Explanation Emphysema The forced vital capacity (FVC) is only slightly reduced, but the ratio of the forced expiratory volume in 1 s (FEV1) to the FVC (FEV1/FVC) is more significantly reduced. Transfer factor is also reduced at 55%. With reversibility of less than 10% post-salbutamol, the most likely diagnosis here is chronic obstructive pulmonary disease (COPD). Stopping smoking is the key initial measure, with trials also indicating that high-dose inhaled steroids combined with long-acting ß2-agonists might reduce exacerbation rates and improve quality of life in comparison with other options. Asbestos-related pleural plaque disease Asbestos-related pleural plaque disease is incorrect. Asbestos-related pleural plaque disease is not associated with abnormal lung function. Asthma Asthma is incorrect. There is less than 10% reversibility in this man’s FEV1 following salbutamol, which means that COPD is more likely. Pulmonary embolism Pulmonary embolism is incorrect. There are no risk factors for pulmonary emboli (PE) mentioned. He has no pleuritic chest pain or leg swelling suggesting deep venous thrombosis. Spirometry in a lone diagnosis of PE would likely be normal. Pulmonary fibrosis Pulmonary fibrosis is incorrect. Pulmonary fibrosis is associated with a restrictive pattern of spirometry.

Question 7

A 60-year-old woman presents with chronic progressive shortness of breath and bibasal crepitations. Which of the following is the most likely diagnosis?

Explanation

Correct Answer: B- Idiopathic pulmonary fibrosis Explanation Idiopathic pulmonary fibrosis Idiopathic pulmonary fibrosis is characterised by an inflammatory cell infiltrate. The main symptoms are dry cough, exertional dyspnoea and malaise. Signs include cyanosis, finger clubbing and fine end-inspiratory crepitation at the bases and in the axillae. Bilateral lower- zone reticulonodular shadows are seen on chest X-ray. Lung damage is often irreversible but pirfenidone is recommended between 50% and 80% predicted. Lung transplantation may be considered. Overall, the median survival is 2–3 years following diagnosis. Extrinsic allergic alveolitis Extrinsic allergic alveolitis is incorrect. Extrinsic allergic alveolitis shows a predilection for the upper zones,

although, when severe, can affect all zones. Progressive massive fibrosis Progressive massive fibrosis is incorrect. Progressive massive fibrosis describes a stage of a number of occupational lung diseases which are caused by mineral dusts – silicosis and coal-worker’s pneumoconiosis. When the irregular or linear opacities become large shadows late in the course of these diseases this is then called ‘progressive massive fibrosis’. Sarcoidosis Sarcoidosis is incorrect. Sarcoidosis affects upper zones and midzones, although, when severe, it can affect all zones. Tuberculosis Tuberculosis is incorrect. Tuberculosis shows a predilection for the upper zones, although, when severe, it can affect all zones.

Question 8

Surgical resection in carcinoma of the lung is most likely to be contraindicated in the presence of which one of the following?

Explanation

Correct Answer: B- Forced expiratory volume in 1 s 25% of predicted Explanation Forced expiratory volume in 1 s 25% of predicted Pulmonary function assessment does not provide clear- cut answers to the Question: of operability, but there are some simple rules for performing a thoracotomy. The

physician should keep in mind that the extent of resection can be determined only at operation, and pneumonectomy might be needed. The functional criteria for pneumonectomy are therefore:

• Forced expiratory volume in 1 s (FEV1) of > 1.5 l •

FEV1 > 50% of the observed forced vital capacity • Normal partial pressure of arterial CO2 (Paco2) with the patient at rest Taking a 50-year-old man as an example, he would have a predicted FEV1 of 5 l. As such 25% of 5 l equals 1.25 l, below the likely requirement of 1.5 l. Adenocarcinoma Adenocarcinoma is incorrect. Localised adenocarcinoma may be surgically resected. Ischaemic heart disease Ischaemic heart disease is incorrect. Presence of ischaemic heart disease will increase surgical risk and decisions would be made on a case by case basis depending on severity of coronary disease and cardiac function. Lung cancer resection woud be contraindicated within 30 days of acute myocardial infarction due to increased risk of perioperative mortaility. Pulmonary artery involvement Pulmonary artery involvement is incorrect. Pulmonary artery involvement is not a contraindication to surgery. Superior vena cava obstruction Superior vena cava obstruction is incorrect. Superior vena cava obstruction may be extrinsic; as such, there is still a very small chance that resection may be possible.

Question 9

A 22-year-old student attends the clinic for his 6-week check after admission with pneumonia. Which of the following complications of pneumonia is most likely to be a chronic rather than an acute complication of the infective process?

Explanation

Correct Answer: A- Bronchiectasis Explanation Bronchiectasis This is a ‘know it or you don’t’ question. The diagnosis of bronchiectasis can only be made after the illness because temporary or reversible bronchial dilatation is sometimes seen during the acute illness. Bronchopleural fistula Bronchopleural fistula is incorrect. Bronchopleural fistula is an acute complication of the infective process. Empyema Empyema is incorrect. Empyema is an acute complication of the infective process. Lung abscess Lung abscess is incorrect. Lung abscess is an acute complication of the infective process. Organising pneumonia Organising pneumonia is incorrect. Organising pneumonia is an acute complication of the infective process.

Question 10

A 54-year-old man who has a suspicious area on his chest X-ray, thought to be a tumour on CT scanning, is referred for PET imaging. Which of the following is the usual tracer used for PET imaging in lung cancer?

Explanation

Correct Answer: C- Fluorodeoxyglucose Explanation Fluorodeoxyglucose Rapidly dividing tumour cells of course require large amounts of glucose to satisfy their energy needs. As such it is avidly taken up by tumour cells and phosphorylated by hexokinase, which then allows it to be visualised on PET scanning. Alanine Alanine is incorrect. Alanine is not a tracer used for PET imaging in lung cancer. Aspartame Aspartame is incorrect. Aspartame is not a tracer used for PET imaging in lung cancer. Fluorodopa Fluorodopa is incorrect. Fluorodopa (FDOPA) is a tracer used in the imaging of adrenal tumours. Metomidate Metomidate is incorrect. Metomidate is a tracer used in the imaging of adrenal tumours.

Question 11

A 65-year-old man complains of lethargy, fever, dry cough, headache, chest pain and increasing shortness of breath. He returned from a cruise 2 days ago. His chest X-ray shows bilateral infiltrates, the Po2 is 8.35 kPa. What is the most appropriate therapy?

Explanation

Correct Answer: C- Erythromycin Explanation Erythromycin This patient has Legionella pneumonia. The most relevant factor in treatment is the ability of the antibiotic to penetrate intracellularly into alveolar macrophages where the Legionellaorganism hides and divides. A macrolide antibiotic, such as erythromycin or clarithromycin, is at present recommended as the drug of first choice, in dosages of 500–1000 mg every 6 hours for erythromycin and 500 mg twice daily for clarithromycin, being given intravenously if required. In-vitro and animal experiments and clinical experience support the efficacy of rifampicin and fluoroquinolones. Rifampicin is often recommended as additional therapy to erythromycin, in a dose of 600 mg once or twice daily in patients with severe infection or who are deteriorating. General supportive measures are particularly important, with attention to adequate hydration and correction of hypoxaemia with the early use of assisted ventilation for advancing respiratory failure. The most important principle to follow is to avoid holding water at temperatures between 20 °C and 45 °C, which is the range in which Legionella multiplication occurs. Other preventive measures should be taken, such as:

• Minimisation of colonisation, growth and release of Legionella organisms into the atmosphere •

Physical or chemical treatment of water to kill the bacteria • Protection of maintenance personnel who work on contaminated systems. Amphotericin B Amphotericin B is incorrect. Amphoterecin B would be appropriate in severe fungal infection, not in Legionella pneumonia. Ampicillin Ampicillin is incorrect. Ampicillin would not treat Legionella pneumonia adequately. Intravenous corticosteroids Intravenous corticosteroids is incorrect. Intravenous steroids are not an appropriate treatment for severe Legionella pneumonia and would immunosuppress the patient, leaving him at risk of disseminated infection/sepsis. Isoniazid Isoniazid is incorrect. Isoniazid is an appropriate therapy for tuberculosis, not for Legionellapneumonia.

Question 12

A 29-year-old woman with brittle asthma is admitted to the Emergency Department with a viral exacerbation of her asthma. Her usual peak flow is around 490 l/min and she is managed with a high-dose Seretide® inhaler. On examination her blood pressure is 145/80 mmHg, pulse 105 bpm and regular. She has a respiratory rate of 40/min and looks exhausted. On auscultation you can hear wheeze and decreased air entry. Her peak flow is measured at 180 l/min.

Investigation:

Hb 13.1 g/dl

WCC 8.1 x 109/l

PLT 249 x 109/l

Sodium 141 mmol/l

Potassium 3.9 mmol/l

Creatinine 110 µmol/l

paO2 10.5 kPa

pCO2 6.4 kPa Her peak flow has not improved 30 min after admission despite salbutamol and Atrovent® nebulisers and intravenous hydrocortisone. You arrange review by the Intensive Therapy Unit registrar. While you are waiting for her visit, which of the following is the most appropriate next management step?

Explanation

Correct Answer: C- Intravenous magnesium Explanation Intravenous magnesium A Cochrane meta-analysis showed some benefit from intravenous magnesium in acute asthma, and for this reason it is recommended in acute severe asthma that has not responded to inhaled bronchodilator therapy. Her

Pco2 is just outside the upper limit of normal, so she requires urgent admission to the Intensive Therapy Unit. Inhaled helium/oxygen mixture Inhaled helium oxygen mixture is incorrect. Inhaled helium/oxygen mixture is used in the treatment of vocal cord dysfunction. Intravenous aminophylline Intravenous aminophylline is incorrect. In acute asthma, IV aminophylline is not likely to result in any additional bronchodilation compared to standard care with inhaled bronchodilators and steroids. Side effects such as stomach pain/cramping and vomiting are increased if IV aminophylline is used. Therefore, it is not recommended routinely and should only be used in specific patients after consultation with senior staff. Intravenous salbutamol Intravenous salbutamol is incorrect. Intravenous salbutamol should be reserved for individuals in whom inhaled salbutamol cannot be used reliably. Non-invasive positive-pressure ventilation Non-invasive positive-pressure ventilation (NIPPV) is incorrect. NIPPV should not be used to treat acute asthma. Ventilation, if required should be invasive.

Question 13

A 62-year-old woman is admitted with confusion and increased respiratory rate. She has been managed by her GP for shortness of breath and is taking ramipril and indapamide for hypertension and has a salbutamol inhaler. She came to the Emergency Department with her daughter because of concerns that she was getting worse. On examination her blood pressure is 112/62 mmHg and she has a pyrexia of 37.8 °C. The pulse is 75 bpm and regular and the heart sounds are normal. Auscultation of the chest reveals scattered crackles and wheeze.

Investigations show:

Hb 13.1 g/dl

WCC 9.2 x 109/l

Platelets 201 x 109/l Sodium 138 mmol/l

Potassium 4.5 mmol/l

Bicarbonate 24 mmol/l

Creatinine 130 μmol/l

Po2 9.1 kPa

Pco2 7.2 kPa

pH 7.2 Which of the following is the most likely diagnosis?

Explanation

Correct Answer: B- Acute respiratory acidosis Explanation Acute respiratory acidosis This woman is hypercapnic with decreased pH. This has occurred too quickly for metabolic compensation to occur via renal bicarbonate reabsorption, which takes 3– 5 days to occur. It is therefore an acute event such as a chronic obstructive pulmonary disease (COPD) exacerbation that is most likely to have led to her deterioration in symptoms. Aggressive management is therefore likely to return her to a reasonable level of function. Acute on chronic respiratory acidosis Acute on chronic respiratory acidosis is incorrect. This woman is hypercapnic with decreased pH. This has occurred too quickly for metabolic compensation to occur via renal bicarbonate reabsorption, which takes 3– 5 days to occur. It is therefore an acute event such as COPD exacerbation that is most likely to have led to her deterioration in symptoms. Chronic respiratory acidosis Chronic respiratory acidosis is incorrect. This woman is hypercapnic with decreased pH. This has occurred too quickly for metabolic compensation to occur via renal

bicarbonate reabsorption, which takes 3–5 days to occur. It is therefore an acute event such as COPD exacerbation that is most likely to have led to her deterioration in symptoms. Metabolic acidosis Metabolic acidosis is incorrect. Bicarbonate would be low in metabolic acidosis. Mixed metabolic and respiratory acidosis Mixed metabolic and respiratory acidosis is incorrect.

Bicarbonate would be low in metabolic acidosis.

Question 14

A 50-year-old woman comes to the clinic complaining of breathlessness on exertion, which has been worsening for 1 year. This is accompanied by wheeze which worsens with exercise, and during the course of the summer when she also has severe hayfever. She has never smoked. The chest X-ray shows mild hyperinflation but is otherwise unremarkable. Her lung function test results are shown below:

Test Result Predicted

FEV1 (l) 1.1 1.7-3.0

FVC (l) 2.7 2.0-3.5 FRC (l) 4.2 1.7-3.4

TLC (l) 6.5 3.6-5.6

Tlco (mmol/min per kPa) 5.86 5.7-9.5 Kco (mmol/min per kPa per l) 1.63 1.66 What is the most likely diagnosis?

Explanation

Correct Answer: A- Asthma Explanation Asthma This woman has obstructive spirometry, with raised lung volumes. This is suggestive of asthma or chronic obstructive pulmonary disease (COPD). She has never smoked and has a normal transfer factor and so she is more likely to have asthma. Bronchiectasis Bronchiectasis is incorrect. Bronchiectasis can lead to a mild obstructive defect, but would not tend to show such marked hyperinflation. History would usually include a chronic productive cough. Chronic obstructive pulmonary disease Chronic obstructive pulmonary disease is incorrect. Non- smokers can develop COPD, but they tend to have a heavy passive smoke exposure and be older. Interstitial lung disease Interstitial lung disease is incorrect. Interstitial lung disease would lead to a restrictive defect with a reduced transfer factor. Pulmonary haemorrhage Pulmonary haemorrhage is incorrect. There are no features in the history to suggest pulmonary haemorrhage, which would have a much shorter history plus potentially coexistent symptoms of vasculitis or renal failure. Pulmonary haemorrhage would lead to a raised Tlco and Kco (transfer factor and transfer coefficient for carbon monoxide).

Question 15

A 54-year-old man with a 40-pack-year smoking history presents to the Respiratory Clinic complaining of a chronic cough and haemoptysis. He has lost 4 kg in weight recently. He has an abnormal chest X-ray, consistent with bronchial carcinoma.

Investigations:

Hb 11.0 g/dl

WCC 6.1 x 109/l

PLT 352 x 109/l

ESR 65 mm in 1 hour

Sodium 132 mmol/l

Potassium 3.9 mmol/l

Creatinine 130 µmol/l Bronchoscopy with transbronchial biopsy reveals adenocarcinoma of the bronchus. You arrange computed tomography of the thorax. Which of the following would tend to rule out the possibility of a surgical cure?

Explanation

Correct Answer: D- Malignant pleural effusion Explanation Malignant pleural effusion Pleural effusion implies pleural involvement and this would preclude a surgical cure. Forced expiratory volume in 1 s (FEV1) 1.6 l Forced expiratory volume in 1 s (FEV1) 1.6 l is incorrect. A forced expiratory volume in 1 s (FEV1) of less than 1.5 l precludes surgery for bronchial carcinoma because there is not enough lung reserve. Horner syndrome Horner syndrome is incorrect. Horner syndrome is attributable to local nerve involvement and therefore does not exclude successful surgical excision of the primary tumour. Ipsilateral mediastinal lymph node involvement Ipsilateral mediastinal lymph node involvement is incorrect. Contralateral lymph node involvement implies distant spread and again precludes surgery. Superior vena caval obstruction Superior vena caval obstruction is incorrect. Superior vena caval obstruction is not an absolute contraindication to surgery.

Question 16

A 40-year-old man presents with a 2-month history of cough and breathlessness. He has also noted haemoptysis, which he says has gradually worsened. On examination he has bilateral basal crepitations. His chest X-ray shows diffuse shadowing. He has moderate renal failure. What is the most likely diagnosis?

Explanation

Correct Answer: B- Goodpasture syndrome Explanation Goodpasture syndrome Goodpasture described a case of a man with renal failure, glomerulonephritis and pulmonary haemorrhage. Goodpasture syndrome consists of diffuse pulmonary haemorrhage and glomerulonephritis with linear deposition of antibodies (90% of which are directed against the α3 chain of type IV collagen) along the glomerular basement membrane (GBM). In practice, glomerulonephritis proves to be a much more common threat to survival than lung haemorrhage, and the diagnosis of Goodpasture syndrome is reached more conveniently by serological testing (for anti-GBM antibodies) and from kidney rather than lung biopsy. In some cases, lung disease dominates the clinical picture. The majority of these patients are male smokers and some report a recent exposure to volatile hydrocarbons. In addition, case reports have identified recent exposure to chlorine and smoked cocaine as relevant factors. This suggests that, when there is susceptibility, inhaled toxic agents enhance pulmonary endothelial damage and allow the initiation of autoimmunity or the ready access of existing autoantibody to basement membrane. Respiratory presentation is with cough, breathlessness and haemoptysis, which is intermittent and ranges from occasional streaks to massive fatal bleeding. Systemic symptoms of fever, joint pains or weight loss are unusual. The chest X-ray shows patchy or diffuse shadowing due to intra-alveolar blood, usually resolving over the course of 2 weeks unless there is further bleeding. At the time of bleeding there may be arterial hypoxaemia and reduced lung volumes. Serial measurement of carbon monoxide (CO) diffusing capacity or transfer factor (Tlco) can be used to monitor progression, and prolonged bleeding can lead to iron deficiency anaemia. The Tlco is widely used as a simple test of the integrity of the alveolar capillary membrane and of the overall gas-exchanging function of the lungs. It has good sensitivity but poor specificity, as impairment can result from a variety of pathological processes. Renal function can be normal initially but then deteriorates over days to weeks. Steroids, other immunosuppressant drugs (cyclophosphamide in particular) and plasmapheresis are all used (in some circumstances) to control renal disease, and are additionally helpful in treating pulmonary haemorrhage. Patients should not smoke and should avoid hydrocarbon exposure. Bronchial carcinoma Bronchial carcinoma is incorrect. Bronchial carcinoma is a reasonable differential diagnosis in view of his history of cough, breathlessness and haemoptysis. However, the examination and X-ray findings are not classical of bronchial carcinoma and, in conjunction with the presence of renal failure, a diagnosis of vasculitis, namely Goodpasture syndrome, is more likely. Legionella pneumonia Legionella pneumonia is incorrect. The 2-month history of symptoms makes a pneumonia an unlikely cause of this man’s symptoms. Haemoptysis in legionella pneumonia is uncommon and legionella pneumonia is not directly associated with renal failure. Pulmonary embolism Pulmonary embolism is incorrect. The clinical examination and chest X-ray findings, along with the presence of renal failure, are not in keeping with pulmonary embolism. Clinical examination of the chest is usually normal in pulmonary embolism and chest X- ray is typically also normal, although an area of lung infarction may be seen with large emboli. Tuberculosis Tuberculosis is incorrect. Miliary tuberculosis could potentially present with the symptoms described in this history, but if miliary tuberculosis was present then the classical ‘millet seed’ appearance on chest X-ray would likely be seen and there would also almost certainly be bilateral hilar lymphadenopathy. The absence of these findings, in addition to the fact that classical infective symptoms such as fevers, night sweats and purulent sputum are not mentioned here and there is no suggestion of risk factors for tuberculosis, makes vasculitis a more likely diagnosis.

Question 17

A 28-year-old woman comes to the clinic for review 4 weeks after discharge from the ward following an asthma attack. She was diagnosed with asthma at the age of 7 years and has been taking inhaled beclometasone 400 μg and salbutamol as required since then. She tells you that since discharge she has been using her salbutamol three times a day and has been waking two or three times a night with coughing. On examination, her peak flow is 340 l (predicted is 570 l). She has scattered wheeze throughout both lung fields on examination. She had a good inhaler technique with volumatic as assessed in the clinic.

Investigation:

Hb 13.1 g/dl

WCC 6.5 x 109/l

PLT 231 x 109/l

ESR 12 mm in 1 hour

Sodium 140 mmol/l

Potassium 4.9 mmol/l

Creatinine 80 µmol/l The chest X-ray shows no evidence of consolidation. Which of the following is the most appropriate management plan for her?

Explanation

Correct Answer: C- Add oral montelukast to her regimen Explanation Add oral montelukast to her regimen Adding oral montelukast is now recommended as a trial in patients who have failed to gain control on low dose inhaled corticosteroids by NICE 2017 guidelines. Add low-dose oral theophylline to her regimen Add low-dose oral theophylline to her regimen is incorrect. Low-dose oral theophylline is an option after addition of salmeterol. Add omalizumab Add omalizumab is incorrect. Omalizumab, an anti-IgE antibody, is reserved for patients with severe allergic asthma in whom other treatments have been unsuccessful and require at least four acute courses of corticosteroids per year. Add twice-daily inhaled salmeterol to her regimen NICE guidelines 2017 now recommend a trial of Montelukast before moving to the addition of a long- acting beta agonist (LABA) in patients who are not controlled on lower doses of inhaled corticosteroids. Change her to 800 μg of fluticasone Change her to 800 μg of fluticasone is incorrect. Fluticasone is twice as potent as beclomethasone, so this option is significantly increasing the amount of steroid medication. This option could be considered after addition of monteleukast or LABA.

Question 18

A 25-year-old man sustains a displaced, vertically oriented femoral neck fracture (Pauwels type III). Closed reduction is attempted but is unsuccessful. What is the most appropriate next step in management?

Explanation

In young adults with displaced femoral neck fractures, preservation of the native hip is prioritized. An irreducible fracture mandates open reduction and stable internal fixation to minimize the risk of nonunion and avascular necrosis.

Question 19

A 12-year-old obese boy presents with left knee pain and a waddling gait. Radiographs reveal a severe slipped capital femoral epiphysis (SCFE) on the left. The right hip is radiographically normal. Which of the following is the primary indication for prophylactic pinning of the contralateral right hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated in patients with underlying endocrine disorders (such as hypothyroidism) or those treated prior to age 10. These factors significantly increase the risk of a contralateral slip.

Question 20

A 65-year-old man with cervical spondylotic myelopathy presents with worsening hand clumsiness and gait imbalance. During examination, flicking the nail of the middle finger produces reflex flexion of the thumb and index finger. This clinical sign indicates pathology involving which of the following?

Explanation

The clinical finding described is Hoffmann's sign, which indicates upper motor neuron dysfunction. In the context of cervical spondylosis, it is a key exam finding for cervical myelopathy caused by spinal cord compression.

Question 21

A 30-year-old carpenter lacerates his volar index finger, resulting in a Zone II flexor tendon injury. Following primary repair of the flexor digitorum profundus and superficialis, which rehabilitation protocol is most appropriate to minimize adhesion formation while protecting the repair?

Explanation

Early controlled motion protocols, such as the Kleinert or modified Duran protocols, are standard for Zone II repairs. This stresses the repair enough to prevent dense adhesions while avoiding excessive tension that could lead to rupture.

Question 22

A 15-year-old boy presents with knee pain. Radiographs show a destructive, bone-forming lesion in the distal femoral metaphysis with a periosteal "sunburst" reaction. If a biopsy is planned, which of the following principles must be strictly followed?

Explanation

When performing a biopsy of a suspected primary bone sarcoma, the biopsy tract must be carefully planned so it can be excised en bloc with the tumor during definitive surgery. Transverse incisions and exsanguination are strictly contraindicated.

Question 23

In total hip arthroplasty, the use of highly cross-linked polyethylene (HXLPE) has significantly reduced wear rates. Which of the following is a recognized mechanical trade-off associated with the increased cross-linking process?

Explanation

While highly cross-linked polyethylene drastically reduces volumetric wear and osteolysis risk, the cross-linking process and thermal treatments reduce its mechanical properties. This specifically decreases its fracture toughness, yield strength, and fatigue resistance.

Question 24

A 22-year-old soccer player sustains a twisting injury to the knee. Radiographs reveal an avulsion fracture of the lateral tibial plateau (Segond fracture). This finding is most highly associated with a tear of which structure?

Explanation

A Segond fracture is an avulsion fracture of the anterolateral tibial plateau and is considered pathognomonic for an anterior cruciate ligament (ACL) tear. It represents an avulsion of the anterolateral ligament or lateral capsular attachments.

Question 25

A 40-year-old man is involved in a high-speed motor vehicle collision. Pelvic radiographs show an anteroposterior compression (APC) Type II injury, with widening of the pubic symphysis of 3.5 cm and widening of the anterior sacroiliac joints. Which ligaments are classically disrupted in this specific injury pattern?

Explanation

In an APC II pelvic ring injury, there is disruption of the symphysis pubis, the anterior sacroiliac ligaments, and the pelvic floor ligaments (sacrotuberous and sacrospinous). The posterior sacroiliac ligaments remain intact, providing vertical stability.

Question 26

During secondary bone healing of a long bone fracture treated with a cast, a soft callus forms. Which type of collagen is the predominant structural component of this early soft callus?

Explanation

In secondary bone healing, the soft callus is composed primarily of cartilaginous tissue, which is predominantly made of Type II collagen. As endochondral ossification progresses, this is gradually replaced by Type X and eventually Type I collagen.

Question 27

A 28-year-old construction worker drops a heavy beam on his midfoot. Radiographs demonstrate widening of the space between the bases of the first and second metatarsals, with a small bony avulsion fragment in the interval. The Lisfranc ligament connects which two structures?

Explanation

The Lisfranc ligament is a strong interosseous ligament that connects the medial cuneiform to the base of the second metatarsal. It is a critical stabilizer of the midfoot, and its rupture leads to tarsometatarsal instability.

Question 28

A 6-week-old female infant with developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. During a follow-up visit, she is noted to have an inability to actively extend the knee on the treated side. This complication is most likely due to excessive positioning in which direction?

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and is typically caused by excessive hip flexion. The harness should be adjusted or temporarily discontinued until quadriceps function returns.

Question 29

According to the Denis three-column theory of the spine, a burst fracture of the L1 vertebra involves failure of which spinal columns?

Explanation

The Denis classification defines a burst fracture as involving failure of both the anterior and middle columns under axial loading. Failure of the middle column distinguishes it from a simple anterior compression fracture.

Question 30

A 24-year-old man presents with radial-sided wrist pain after a fall on an outstretched hand. Radiographs show a displaced fracture of the proximal pole of the scaphoid. Why is this specific fracture pattern at a particularly high risk for avascular necrosis (AVN)?

Explanation

The scaphoid receives its primary blood supply from branches of the radial artery that enter distally and dorsally, providing retrograde perfusion to the proximal pole. Proximal pole fractures disrupt this blood supply, causing high rates of AVN.

Question 31

A 35-year-old woman is diagnosed with an unresectable giant cell tumor of the sacrum. Her oncologist prescribes denosumab. What is the mechanism of action of this medication in the treatment of giant cell tumor of bone?

Explanation

Denosumab is a human monoclonal antibody that binds to the Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL). This prevents the activation and maturation of the osteoclast-like giant cells that cause bone destruction.

Question 32

During a primary total knee arthroplasty in a patient with a severe fixed varus deformity, the surgeon notes a tight medial compartment in both flexion and extension. After removing osteophytes, which structure is typically the next to be released to achieve coronal balance?

Explanation

In balancing a varus knee during TKA, medial release is performed systematically. After osteophyte removal, the deep medial collateral ligament is typically the first soft tissue structure released off the proximal tibia.

Question 33

A 28-year-old man undergoes arthroscopic Bankart repair for recurrent anterior shoulder instability. To prevent a large, engaging Hill-Sachs lesion from engaging the anterior glenoid rim, the surgeon performs a "remplissage". What does this procedure entail?

Explanation

The remplissage procedure addresses an engaging Hill-Sachs lesion by filling the defect in the posterolateral humeral head with the infraspinatus tendon and posterior capsule. This converts an intra-articular defect into an extra-articular one.

Question 34

A 55-year-old man sustains a tibial plateau fracture following a varus-directed force to the knee. Radiographs reveal a medial tibial plateau fracture with depression (Schatzker Type IV). What is the most critical associated soft-tissue risk with this specific injury pattern?

Explanation

Schatzker Type IV fractures (medial plateau) are typically caused by high-energy varus forces and are highly associated with knee subluxation or dislocation. Consequently, they carry a high risk of injury to the popliteal artery and common peroneal nerve.

Question 35

A 13-year-old obese male presents with left hip pain and an antalgic gait. Radiographs reveal a 'slip' of the capital femoral epiphysis. The pathophysiology of this condition involves mechanical failure through which specific histologic zone of the physis?

Explanation

Slipped capital femoral epiphysis (SCFE) occurs through the hypertrophic zone of the physis. This zone is the weakest layer biomechanically as it lacks the collagen shear strength found in other zones.

Question 36

A 32-year-old male is admitted after sustaining a closed tibial shaft fracture. He complains of worsening leg pain out of proportion to his injury. On examination, passive plantar flexion of the toes elicits excruciating pain in the anterolateral aspect of the leg. Which fascial compartment is most likely experiencing critically elevated pressures?

Explanation

The anterior compartment of the leg contains the extensor hallucis longus and extensor digitorum longus. Passive plantar flexion stretches these muscles, eliciting severe pain characteristic of acute anterior compartment syndrome.

Question 37

A 65-year-old female presents with worsening hand dexterity, dropping objects, and a broad-based, unsteady gait. Physical examination reveals a positive Hoffmann sign and hyperreflexia in the lower extremities. Which of the following is the most sensitive imaging modality for evaluating the suspected pathology?

Explanation

The clinical presentation is classic for cervical spondylotic myelopathy. MRI of the cervical spine is the most sensitive and specific modality to evaluate spinal cord compression and intramedullary signal changes.

Question 38

A 24-year-old male is undergoing an anterior cruciate ligament (ACL) reconstruction. A bone-patellar tendon-bone (BPTB) autograft is chosen. Compared to a multi-stranded hamstring autograft, the BPTB graft is statistically associated with a higher incidence of which postoperative complication?

Explanation

Bone-patellar tendon-bone (BPTB) autografts are associated with a higher rate of anterior knee pain and kneeling pain compared to hamstring autografts. Overall graft survival and functional stability rates are comparable between the two.

Question 39

A 70-year-old male is scheduled for a total hip arthroplasty (THA). The surgeon selects a highly cross-linked polyethylene liner. What is the primary biomechanical advantage of highly cross-linked polyethylene compared to conventional polyethylene?

Explanation

Highly cross-linked polyethylene significantly reduces volumetric wear and subsequent wear-debris mediated osteolysis in THA. However, the cross-linking process decreases the material's fracture toughness and fatigue resistance.

Question 40

A 15-year-old male presents with persistent distal femur pain. Radiographs show a destructive metaphyseal lesion with a 'sunburst' periosteal reaction and Codman's triangle. Biopsy reveals pleomorphic spindle cells producing immature osteoid. What is the most common site of metastasis for this primary tumor?

Explanation

The clinical and histologic findings are diagnostic of osteosarcoma. The most common site of metastasis for osteosarcoma is the lungs, followed by other bones.

Question 41

A 28-year-old carpenter suffers a flexor tendon laceration in Zone II of the hand. Which anatomical boundaries strictly define flexor tendon Zone II?

Explanation

Zone II (historically 'no man\'s land') extends from the proximal edge of the A1 pulley to the insertion of the FDS tendon. Repair in this zone is complex due to both FDS and FDP traversing within a tight fibro-osseous sheath.

Question 42

A 28-year-old male sustains a high-energy motor vehicle collision resulting in a displaced, vertical femoral neck fracture (Pauwels Type III). What is the most biomechanically stable surgical fixation strategy for this specific fracture pattern?

Explanation

Pauwels Type III fractures are highly vertical and subject to massive shear forces. A sliding hip screw with a derotation screw (or a proximal femoral locking plate) provides superior biomechanical stability against shear compared to standard cannulated screws.

Question 43

During secondary bone healing, which phase is classically characterized by the highest peak of cellular proliferation, angiogenesis, and the formation of a fibrocartilaginous soft callus?

Explanation

The reparative phase features massive cellular proliferation, ingrowth of capillaries (angiogenesis), and the deposition of a fibrocartilaginous network that forms the soft callus. This soft callus eventually mineralizes into hard woven bone.

Question 44

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed 6 weeks of strict Pavlik harness treatment. What is the next best step in management?

Explanation

In an infant (typically under 18 months) who fails Pavlik harness treatment, the next appropriate step is an examination under anesthesia, arthrogram, and closed reduction with spica casting. Open reduction is reserved for failure of closed reduction.

Question 45

A 60-year-old male reports bilateral posterior leg pain and heaviness that worsens after 10 minutes of walking but is rapidly relieved when he leans forward on a shopping cart. MRI demonstrates severe L4-L5 central canal stenosis. Hypertrophy of which ligament significantly contributes to this central canal narrowing?

Explanation

Lumbar spinal stenosis is primarily caused by a combination of disc bulging, facet joint arthropathy, and hypertrophy or buckling of the ligamentum flavum, which directly compresses the dorsal aspect of the thecal sac.

Question 46

A 45-year-old female presents with numbness and tingling in her thumb, index, and long fingers that awakens her at night. Electromyography confirms isolated prolonged sensory latencies in the median nerve at the wrist. Which structure forms the roof of the anatomical space where compression is occurring?

Explanation

The patient has carpal tunnel syndrome. The roof of the carpal tunnel is formed by the transverse carpal ligament, which is surgically released to relieve pressure on the median nerve.

Question 47

A 22-year-old soccer player sustains a sudden twisting injury to the knee. MRI reveals an isolated, 1.5 cm longitudinal tear in the peripheral one-third of the medial meniscus. What is the most appropriate surgical management?

Explanation

The peripheral one-third of the meniscus (the 'red-red' zone) has an excellent vascular supply. Longitudinal tears in this region have high healing rates and should be treated with meniscal repair to preserve joint biomechanics.

Question 48

According to the Musculoskeletal Infection Society (MSIS) criteria, which of the following findings is considered a major criterion, sufficient on its own to definitively diagnose a periprosthetic joint infection (PJI)?

Explanation

The MSIS major criteria for PJI are: 1) a sinus tract communicating with the joint, or 2) two positive periprosthetic cultures with phenotypically identical organisms. The other options represent minor criteria.

Question 49

A 30-year-old male complains of severe midfoot pain after falling from a horse with his foot caught in the stirrup. Examination reveals significant swelling and plantar ecchymosis. Radiographs show widening between the base of the 1st and 2nd metatarsals. Which structure is primarily injured?

Explanation

The clinical picture describes a Lisfranc injury. Plantar ecchymosis is highly suggestive. The Lisfranc ligament connects the medial cuneiform to the base of the second metatarsal, stabilizing the midfoot.

Question 50

A 35-year-old female presents with knee pain. Radiographs demonstrate an eccentric, expansile, lytic, epiphyseal lesion in the proximal tibia. Biopsy reveals numerous multinucleated giant cells within a stroma of mononuclear cells. If medical therapy is considered, denosumab would be used to target which of the following?

Explanation

The diagnosis is a Giant Cell Tumor of bone. Denosumab is a monoclonal antibody that binds and inhibits RANKL, which normally promotes the recruitment and maturation of the osteoclast-like giant cells that drive tumor osteolysis.

Question 51

A 40-year-old male is brought to the emergency department after severe pelvic trauma and is hemodynamically unstable. A pelvic binder is ordered to reduce pelvic volume. At what specific anatomical landmark should the binder be centered for optimal effectiveness?

Explanation

Pelvic binders must be centered directly over the greater trochanters to effectively compress the pelvic ring. Placement higher up (e.g., iliac crests) can paradoxically widen the pelvis in certain open-book fracture patterns.

Question 52

A 5-year-old boy falls on an outstretched hand. Radiographs confirm a completely displaced, extension-type supracondylar humerus fracture. Which nerve is most commonly injured in this specific fracture pattern?

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most frequently injured nerve in extension-type supracondylar humerus fractures. Injury manifests clinically as the inability to form an 'OK' sign.

Question 53

A 20-year-old male sustains a fall on an outstretched hand and complains of radial wrist pain. Clinical examination reveals localized tenderness in the anatomical snuffbox. Radiographs confirm a nondisplaced scaphoid waist fracture. Why is this fracture at a disproportionately high risk for nonunion and avascular necrosis?

Explanation

The scaphoid receives its primary blood supply from branches of the radial artery that enter distally and flow in a retrograde fashion. Fractures at the waist or proximal pole disrupt this supply, leading to high rates of proximal pole AVN and nonunion.

Question 54

During laboratory biomechanical testing of a human tendon, the tendon is rapidly stretched to a specific length and held constantly at that length. Over time, the internal force required to maintain this stretch gradually decreases. What is this specific viscoelastic phenomenon called?

Explanation

Stress relaxation is a viscoelastic property where the stress (internal force) decreases over time when the material is held at a constant strain (length). Creep, conversely, is increasing deformation under a constant load.

Question 55

A 3-year-old boy presents to the emergency department with an isolated, closed, midshaft femur fracture after a fall from a playground structure. There is 1.5 cm of shortening on radiographs. What is the most appropriate definitive management?

Explanation

In children younger than 5 years old with isolated femur fractures and less than 2 cm of shortening, a hip spica cast is the gold standard treatment. Flexible nailing is generally reserved for children aged 5 to 11 years.

Question 56

A 14-year-old boy complains of progressive distal thigh pain that awakens him at night. Radiographs reveal a metaphyseal, poorly defined lytic lesion with a 'sunburst' periosteal reaction and Codman's triangle. What is the most likely diagnosis?

Explanation

Osteosarcoma typically presents in the metaphysis of long bones (most commonly the distal femur) in adolescents. The 'sunburst' periosteal reaction and Codman's triangle are classic radiographic findings.

Question 57

A 72-year-old woman presents with severe shoulder pain, pseudoparalysis, and inability to actively elevate her arm above 90 degrees. Radiographs show superior migration of the humeral head and advanced glenohumeral osteoarthritis. MRI confirms a massive, retracted rotator cuff tear. What is the most appropriate surgical treatment?

Explanation

Reverse total shoulder arthroplasty is indicated for cuff tear arthropathy. It bypasses the deficient rotator cuff by medialiszing and lowering the center of rotation, allowing the deltoid to effectively elevate the arm.

Question 58

A 25-year-old man sustains a closed tibia fracture. Four hours post-injury, he complains of excruciating pain that is worsened by passive stretch of his toes. Which of the following pressure measurements is the generally accepted threshold for performing an emergency fasciotomy?

Explanation

A delta P (diastolic blood pressure minus intracompartmental pressure) of less than 30 mmHg is the accepted threshold indicating inadequate tissue perfusion and the need for urgent fasciotomy.

Question 59

A 22-year-old man falls on an outstretched hand and sustains a fracture of the proximal pole of the scaphoid. Why is this specific fracture pattern at a high risk for avascular necrosis (AVN) and nonunion?

Explanation

The major blood supply to the scaphoid comes from the dorsal carpal branch of the radial artery, which enters distally and flows proximally. Proximal pole fractures disrupt this retrograde blood supply, leading to high rates of AVN.

Question 60

A patient with an irreparable high radial nerve palsy requires tendon transfers to restore wrist and finger extension. Which muscle is most commonly transferred to the extensor carpi radialis brevis (ECRB) to restore wrist extension?

Explanation

The pronator teres is the standard donor muscle transferred to the ECRB to restore strong and synergistic wrist extension in radial nerve palsy.

Question 61

A 13-year-old overweight boy presents with left knee pain and a limp for 3 weeks. Examination reveals limited internal rotation of the left hip. What obligatory motion of the hip during passive flexion is classic for this condition?

Explanation

Slipped capital femoral epiphysis (SCFE) typically presents with an obligatory external rotation of the thigh as the hip is passively flexed, due to the posterior and inferior displacement of the femoral head.

Question 62

A 24-year-old soccer player sustains a twisting injury to his knee. Radiographs reveal an avulsion fracture of the anterolateral tibial plateau (Segond fracture). This radiographic finding is virtually pathognomonic for an injury to which structure?

Explanation

A Segond fracture is a cortical avulsion off the anterolateral tibia caused by the anterolateral ligament and capsule. It is highly associated with and considered pathognomonic for an anterior cruciate ligament (ACL) tear.

Question 63

A 55-year-old man presents with a painful proximal humerus mass. Imaging shows a lytic lesion with intralesional 'popcorn' calcifications. Biopsy confirms conventional chondrosarcoma. What is the most appropriate primary treatment?

Explanation

Conventional chondrosarcoma is largely resistant to both chemotherapy and radiation. The mainstay of treatment is wide surgical resection to achieve negative margins.

Question 64

In orthopedic basic science, viscoelastic materials like ligaments and tendons exhibit 'creep' when loaded. Which of the following best defines the phenomenon of creep?

Explanation

Creep is the time-dependent deformation of a viscoelastic material when subjected to a constant load. Stress relaxation, conversely, is the decrease in stress over time under a constant deformation.

Question 65

A 4-month-old infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. To avoid iatrogenic avascular necrosis (AVN) of the femoral head, which position must be strictly avoided during harness application?

Explanation

Excessive abduction in a Pavlik harness places extreme pressure on the vascular supply to the femoral head, drastically increasing the risk of iatrogenic avascular necrosis. Care must be taken to keep the hips in a safe zone of abduction.

Question 66

A 68-year-old man presents with a warm, erythematous, and painful knee 3 weeks after an uncomplicated total knee arthroplasty. Aspiration yields 65,000 WBC/mcL with 90% neutrophils. What is the most appropriate surgical management?

Explanation

For acute post-operative periprosthetic joint infections (typically within 4 weeks of surgery), DAIR with exchange of the modular polyethylene insert is the standard of care. Two-stage revision is reserved for chronic infections.

Question 67

A 32-year-old male is involved in a high-speed motor vehicle collision and sustains a highly displaced, vertical femoral neck fracture (Pauwels Type III). What is the preferred surgical treatment?

Explanation

In young patients, joint preservation is paramount. Pauwels Type III fractures are highly vertically oriented and unstable, requiring robust fixed-angle constructs like a sliding hip screw (often with a derotational screw) over parallel cannulated screws.

Question 68

A rugby player grabs an opponent's jersey and feels a sudden pop in his finger. He is unable to actively flex the distal interphalangeal (DIP) joint of the affected digit. Which finger is most commonly involved in this injury?

Explanation

A 'jersey finger' is an avulsion of the flexor digitorum profundus (FDP) tendon from the distal phalanx. It most commonly affects the ring finger, as it extends further than the other digits when the hand is gripping.

Question 69

A patient presents with midfoot pain and plantar ecchymosis after a twisting injury to the foot. Radiographs reveal a 'fleck sign'. The critical ligament injured in this scenario connects which two osseous structures?

Explanation

The Lisfranc ligament connects the medial cuneiform to the base of the second metatarsal. A 'fleck sign' represents an avulsion fracture of this ligament, indicating a severe Lisfranc injury.

Question 70

A 65-year-old man presents with bilateral hand clumsiness, difficulty buttoning his shirt, and a broad-based, unsteady gait. Examination reveals a positive Hoffman's sign. What is the most likely diagnosis?

Explanation

Cervical spondylotic myelopathy classically presents with upper motor neuron signs (like Hoffman's sign), hand clumsiness, loss of fine motor skills, and gait instability due to spinal cord compression in the cervical spine.

Question 71

A 70-year-old woman is started on alendronate for osteoporosis after a distal radius fracture. At the cellular level, what is the primary mechanism of action of this medication?

Explanation

Bisphosphonates like alendronate concentrate in bone and are ingested by osteoclasts. They primarily function by inhibiting the enzyme farnesyl pyrophosphate synthase, disrupting osteoclast function and inducing osteoclast apoptosis.

Question 72

A trauma patient presents with an open-book pelvic fracture (APC Type III) and hemodynamic instability. When applying a pelvic binder for temporary stabilization, over which anatomic landmark should it be centered to be most effective?

Explanation

To effectively close the pelvic ring and reduce intrapelvic volume, a pelvic binder must be centered directly over the greater trochanters of the femurs. Placing it higher over the iliac crests is less effective and can paradoxically open the pelvis further.

Question 73

In total hip arthroplasty, which of the following bearing surface combinations demonstrates the lowest volumetric wear rate in vitro?

Explanation

Ceramic-on-ceramic bearing surfaces are highly scratch-resistant and exhibit the lowest volumetric wear rates of all bearing combinations. However, they carry risks of squeaking and catastrophic ceramic fracture.

Question 74

A 45-year-old recreational tennis player lunges for a ball and feels a snap in the back of his heel, followed by difficulty walking. Which physical examination test is most sensitive and specific for diagnosing this acute injury?

Explanation

The Thompson test involves squeezing the calf muscle of the prone patient. If the Achilles tendon is ruptured, there will be an absence of passive plantarflexion of the foot, indicating a positive test.

Question 75

A 32-year-old man presents with a closed tibial shaft fracture following a motorcycle accident. He complains of severe pain out of proportion to the injury. Which of the following pressure measurements is most indicative of the need for an emergent fasciotomy?

Explanation

A delta pressure (diastolic blood pressure minus compartment pressure) of less than 30 mmHg is the most reliable indicator for diagnosing acute compartment syndrome and necessitates emergent fasciotomy. Absolute pressure readings are less reliable due to variations in systemic blood pressure.

Question 76

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip. At the two-week follow-up, the mother reports the infant is no longer kicking the affected leg. On examination, there is an absence of active knee extension. What is the most likely cause?

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment caused by excessive hyperflexion of the hip. The appropriate management is to temporarily discontinue the harness or adjust the flexion straps until neurologic function returns.

Question 77

A 6-year-old boy presents with a completely displaced posteromedial supracondylar fracture of the humerus (Gartland Type III). Which nerve is most commonly injured in this specific fracture pattern?

Explanation

Posteromedial displacement of the distal fragment puts the radial nerve at greatest risk as it gets tethered over the proximal fragment. In contrast, posterolateral displacement places the anterior interosseous nerve (AIN) and median nerve at higher risk.

Question 78

A 50-year-old man presents with chronic wrist pain. Radiographs reveal Scaphoid Nonunion Advanced Collapse (SNAC) Stage III, characterized by radioscaphoid and capitolunate arthritis, but sparing the radiolunate joint. What is the most appropriate surgical treatment?

Explanation

In SNAC Stage III, arthritis involves the capitolunate joint, which is an absolute contraindication for a proximal row carpectomy. Scaphoid excision and four-corner arthrodesis preserves the healthy radiolunate articulation while eliminating the arthritic joints.

Question 79

A 35-year-old woman presents with knee pain. Radiographs show an eccentric, lytic epiphyseal lesion extending to the articular surface of the distal femur. Biopsy confirms mononuclear cells and multinucleated giant cells. Which targeted pharmacological therapy is specifically indicated for unresectable cases?

Explanation

Giant cell tumors of bone are driven by an overexpression of RANKL by the neoplastic mononuclear cells, which recruits osteoclast-like giant cells. Denosumab is a monoclonal antibody against RANKL and is highly effective for locally advanced or unresectable giant cell tumors.

Question 80

A 72-year-old man presents with chronic right shoulder pain and pseudoparalysis. Radiographs demonstrate severe superior migration of the humeral head with an acromiohumeral distance of 2 mm and glenohumeral osteoarthritis (Hamada grade 4). What is the most reliable surgical option?

Explanation

Reverse total shoulder arthroplasty is the treatment of choice for older patients with massive rotator cuff tear arthropathy and pseudoparalysis. It medializes and distalizes the center of rotation, allowing the deltoid muscle to effectively elevate the arm without a functional rotator cuff.

Question 81

A 13-year-old obese boy presents with a 3-week history of left thigh pain and a limp. On examination, he has an obligate external rotation of the left hip during flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). Which of the following is the most devastating long-term complication of in-situ pinning of this condition?

Explanation

While chondrolysis and impingement can occur, avascular necrosis (AVN) of the femoral head is the most devastating complication following SCFE and its surgical treatment. Unstable SCFEs carry a much higher risk of AVN than stable ones, but poor pin placement can also precipitate it.

Question 82

A 45-year-old man presents to the emergency department with acute onset of severe lower back pain, bilateral sciatica, perineal numbness, and urinary retention with overflow incontinence. MRI reveals a massive L4-L5 central disc herniation. What is the most critical next step in management?

Explanation

This patient has cauda equina syndrome, an absolute orthopedic and neurosurgical emergency. Emergent surgical decompression (laminectomy and discectomy) should be performed ideally within 24-48 hours to maximize the chance of neurologic and sphincter recovery.

Question 83

A 28-year-old man is brought in after a high-speed motor vehicle collision. He is hypotensive (BP 80/40 mmHg) and tachycardic. Pelvic radiographs show an anteroposterior compression (APC) type III injury with completely disrupted sacroiliac joints bilaterally. A pelvic binder has been applied. FAST exam is negative. What is the most appropriate next step to manage his hemodynamics?

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST exam, the bleeding is likely retroperitoneal. Preperitoneal pelvic packing or pelvic angiography with embolization are the appropriate emergent interventions to control venous and arterial hemorrhage.

Question 84

A 40-year-old weekend warrior feels a 'pop' in his distal calf while playing tennis. He has a positive Thompson test. He opts for non-operative management of his acute Achilles tendon rupture. Which rehabilitation protocol provides the lowest re-rupture rate comparable to surgical repair?

Explanation

Recent high-level literature shows that functional rehabilitation utilizing early protected weight-bearing and active range of motion yields re-rupture rates equivalent to operative treatment. This avoids surgical complications like infection or sural nerve injury.

Question 85

A 65-year-old woman undergoes an uncomplicated primary total hip arthroplasty via a posterior approach. Postoperatively, she is noted to have a new-onset foot drop and decreased sensation over the anterolateral leg and dorsum of her foot. Intraoperative records reveal the limb was lengthened by 2.5 cm. Which nerve division is most likely injured, and what anatomical characteristic predisposes it to this specific complication?

Explanation

The common peroneal division of the sciatic nerve is most commonly injured during THA lengthening. Its lateral position and distinct morphology (larger fascicles with less protective epineurial connective tissue) make it significantly more susceptible to stretch-induced ischemia than the tibial division.

Question 86

A 13-year-old obese male presents with progressively worsening right knee pain for 3 weeks and an inability to bear weight on the right leg for the past 24 hours. Radiographs demonstrate a severe, unstable slipped capital femoral epiphysis (SCFE). Which of the following best describes the primary rationale for performing an anterior capsulotomy prior to surgical pinning of this condition?

Explanation

In an unstable SCFE, a massive intracapsular hematoma increases pressure, which can tamponade retinacular blood flow and lead to osteonecrosis (avascular necrosis). An anterior capsulotomy effectively decompresses the joint, thereby mitigating this critical complication.

Question 87

A 28-year-old female presents with severe knee pain. Radiographs reveal an eccentric, lytic epiphyseal lesion extending into the metaphysis of the distal femur with no sclerotic margins. Biopsy confirms a Giant Cell Tumor (GCT) of bone. If medical management with Denosumab is initiated, the drug exerts its primary therapeutic effect by inhibiting which of the following targets?

Explanation

In a Giant Cell Tumor of bone, the true neoplastic cells are the mononuclear stromal cells, which express abnormally high levels of RANKL. Denosumab binds directly to this RANKL, preventing it from activating the RANK receptor on the reactive, bone-resorbing multinucleated giant cells.

Orthopedic Prometric MCQs - Chapter 4 Part 1

Orthopedic Prometric MCQs - Chapter 4 Part 11

Orthopedic Prometric MCQs - Chapter 4 Part 11

Chapter Index