This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 9961
Topic: Biology, Genetics & Bone Healing
In the context of bone healing, what is the primary role of the callus formation stage?
Correct Answer & Explanation
. To provide temporary mechanical stability to the fracture site
Explanation
Callus formation (soft callus followed by hard callus) is a crucial stage in secondary bone healing. Its primary role is to provide temporary mechanical stability to the fracture site, bridging the gap between fracture fragments. This stability allows for subsequent remodeling into lamellar bone. Direct restoration of cortical bone is a feature of primary healing or later remodeling. Angiogenesis occurs earlier, and osteocyte differentiation is part of the bone formation process within the callus.
Question 9962
Topic: Biology, Genetics & Bone Healing
Which of the following is an absolute contraindication to initiating bone mineral density (BMD) testing with DEXA scan?
Correct Answer & Explanation
. Pregnancy
Explanation
Pregnancy is an absolute contraindication to DEXA scanning due to the ionizing radiation exposure to the fetus, even though the dose is low. Other options listed are indications for BMD testing or risk factors for osteoporosis, not contraindications.
Question 9963
Topic: 1. General Principles & Basic Science
Which of the following is typically a feature of osteoarthritis but not inflammatory arthritis (e.g., rheumatoid arthritis)?
Correct Answer & Explanation
. Pain worsening with activity and relieved by rest
Explanation
Pain worsening with activity and relieved by rest is a classic characteristic of osteoarthritis (OA), as it is a mechanical/degenerative process. Inflammatory arthritis, such as rheumatoid arthritis (RA), typically features pain that is worse with rest and improves with activity, prolonged morning stiffness (often > 30 minutes to an hour), systemic symptoms, and often symmetrical polyarticular involvement, accompanied by elevated inflammatory markers (ESR, CRP).
Question 9964
Topic: 1. General Principles & Basic Science
Which type of collagen is primarily found in articular cartilage?
Correct Answer & Explanation
. Type II
Explanation
Type II collagen is the predominant collagen type found in articular cartilage, providing its tensile strength and structural integrity. Type I collagen is found in bone, tendons, ligaments, and skin. Type III is in blood vessels and skin (reticular fibers). Type IV is a major component of basement membranes.
Question 9965
Topic: Biology, Genetics & Bone Healing
Which of the following conditions is characterized by excessive and disorganized bone remodeling leading to enlarged, weakened bones, and often elevated serum alkaline phosphatase levels?
Correct Answer & Explanation
. Paget's disease of bone
Explanation
Paget's disease of bone (osteitis deformans) is characterized by a focal disorder of bone remodeling, involving periods of intense osteoclastic resorption followed by compensatory, but disorganized, osteoblastic bone formation. This leads to enlarged, often weakened, and deformed bones. Serum alkaline phosphatase, a marker of bone formation, is typically markedly elevated. Osteogenesis imperfecta is a genetic collagen defect, osteoporosis is decreased bone mass, osteomalacia is defective mineralization, and fibrous dysplasia is fibrous tissue replacing bone.
Question 9966
Topic: Infection, Pharmacology & VTE
A 58-year-old male presents with acute onset of severe pain, redness, and swelling in his great toe. He reports a history of similar episodes, often after consuming alcohol or red meat. Aspiration of the MTP joint reveals negatively birefringent needle-shaped crystals. What is the most appropriate long-term management to prevent recurrent attacks?
Correct Answer & Explanation
. Allopurinol daily
Explanation
The clinical picture and synovial fluid analysis (negatively birefringent needle-shaped crystals) are diagnostic for gout. For long-term management to prevent recurrent attacks (urate-lowering therapy), Allopurinol is the most appropriate choice. It reduces uric acid production and is used for chronic management. Colchicine and NSAIDs (like indomethacin) are primarily used for acute attack management. A low-purine diet is helpful but usually insufficient alone for recurrent attacks, and a corticosteroid injection is for acute symptom relief.
Question 9967
Topic: Physiology & Rehabilitation
What is the primary function of the medial meniscus in the knee joint?
Correct Answer & Explanation
. Shock absorption and load distribution
Explanation
Both the medial and lateral menisci primarily function in shock absorption, load distribution across the tibiofemoral joint, and joint stability. They also play a role in proprioception. While the menisci contribute to overall joint stability, the primary restraints against anterior tibial translation are the ACL, and against valgus stress are the MCL. Menisci do not enhance rotation or protect the patellar tendon.
Question 9968
Topic: Surgical Anatomy & Approaches
A 55-year-old male undergoes ORIF with a locked compression plate for a humeral shaft fracture. Postoperatively, he develops a wrist drop and inability to extend his thumb and fingers at the MCP joints. Sensory examination reveals hypoesthesia in the dorsal aspect of the first web space. What is the most appropriate initial step in managing this complication?
Correct Answer & Explanation
. Immediate re-exploration of the radial nerve
Explanation
An iatrogenic radial nerve palsy (occurring after surgery) is an absolute indication for immediate surgical exploration. Unlike primary palsies that occur with the injury (which often recover spontaneously), iatrogenic palsies are more likely due to direct nerve transection, entrapment, or severe compression by hardware or retractors. Prompt exploration is crucial to identify and address the cause, which could involve nerve decompression, repair, or removal of offending hardware. Delaying exploration can lead to irreversible nerve damage. EMG/NCS and observation are appropriate for primary palsies, but not for iatrogenic palsies.
Question 9969
Topic: Surgical Anatomy & Approaches
A patient undergoing ORIF of a mid-humeral shaft fracture with a posterior approach is at greatest risk for iatrogenic injury to which of the following structures?
Correct Answer & Explanation
. Radial nerve
Explanation
The radial nerve is particularly vulnerable during surgical approaches to the humeral shaft, especially a posterior approach. It courses obliquely across the posterior aspect of the humerus, approximately 10-14 cm proximal to the lateral epicondyle, passing through the spiral groove. During a posterior approach (e.g., triceps-splitting or triceps-sparing), the radial nerve is at significant risk of direct injury, traction, or entrapment. Other nerves are less directly exposed or are more distal/proximal to the typical mid-shaft fracture zone when using a posterior approach.
Question 9970
Topic: Surgical Anatomy & Approaches
What is the most common nerve injured in humeral shaft fractures?
Correct Answer & Explanation
. Radial nerve
Explanation
The radial nerve is by far the most commonly injured nerve in humeral shaft fractures due to its close anatomical proximity as it winds around the humerus in the spiral groove. Incidence ranges from 8% to 15% with closed fractures. Injuries to other nerves are less common with humeral shaft fractures themselves, though the axillary nerve is more commonly injured with proximal humeral fractures, and the median/ulnar nerves with supracondylar or distal humeral fractures.
Question 9971
Topic: Surgical Anatomy & Approaches
Which of the following surgical approaches for humeral shaft fractures offers direct access to the radial nerve in the spiral groove, making it suitable for both fracture fixation and nerve exploration?
Correct Answer & Explanation
. Posterior approach (triceps-sparing)
Explanation
The posterior approach to the humeral shaft (e.g., triceps-sparing or triceps-splitting) provides excellent direct visualization of the radial nerve in the spiral groove. This makes it a preferred approach when there is a known or suspected radial nerve injury that requires exploration in conjunction with fracture fixation. The anterolateral approach can allow for identification of the radial nerve more distally (after it exits the spiral groove) but the posterior approach offers the most direct and extensive visualization of the nerve along the mid-shaft. The other approaches are less suitable for consistent radial nerve exposure in this region.
Question 9972
Topic: Surgical Anatomy & Approaches
What is a potential complication specifically associated with the anterolateral approach (Henry approach) to the distal humeral shaft?
Correct Answer & Explanation
. Injury to the musculocutaneous nerve or its terminal lateral antebrachial cutaneous branch
Explanation
The anterolateral approach (Henry approach) for the distal humeral shaft involves dissection between the brachialis and the brachioradialis/extensor carpi radialis longus. The musculocutaneous nerve pierces the coracobrachialis proximally and then courses between the biceps and brachialis, innervating both. Distally, it becomes the lateral antebrachial cutaneous nerve. This nerve or its branches are at risk during this approach, particularly when dissecting through or around the brachialis muscle. Injury can lead to weakness in elbow flexion and sensory deficits in the lateral forearm. The other nerves are less directly exposed in this specific approach.
Question 9973
Topic: Surgical Anatomy & Approaches
Which of the following approaches is most appropriate for a fracture of the proximal third of the humeral shaft, particularly when proximal fixation is challenging?
Correct Answer & Explanation
. Deltopectoral approach
Explanation
The deltopectoral approach is the workhorse approach for proximal humeral fractures and the proximal third of the humeral shaft. It utilizes the interval between the deltoid and pectoralis major muscles, providing excellent access to the proximal humerus while preserving the axillary nerve. This approach allows for adequate exposure to apply a plate to the lateral or anterior aspect of the humerus, facilitating stable fixation, especially in fractures with extension into the proximal metaphysis. Other approaches are less suitable for the proximal third, either due to nerve risk (posterior, lateral) or limited exposure (anterolateral, medial).
Question 9974
Topic: Surgical Anatomy & Approaches
A patient is undergoing open reduction and internal fixation of a humeral shaft fracture. During plate application, the surgeon notices a dull, non-pulsatile ooze from a small vessel. Which vessel is most likely to be injured during standard plating of the mid-diaphysis?
Correct Answer & Explanation
. Profunda brachii artery
Explanation
The profunda brachii artery (deep brachial artery) and its accompanying veins run in the spiral groove alongside the radial nerve. During plate application to the mid-diaphysis (especially with posterior or anterolateral approaches), these vessels are at risk of injury. A dull, non-pulsatile ooze is characteristic of venous or smaller arterial branch injury. The brachial artery is larger and more anterior/medial. The circumflex humeral arteries are more proximal. The radial artery is distal to the fracture site at the forearm. Injury to the profunda brachii artery is a known, though usually manageable, complication of humeral shaft surgery.
Question 9975
Topic: Surgical Anatomy & Approaches
What is the typical timeframe for expected radial nerve recovery after a primary closed humeral shaft fracture with a complete radial nerve palsy?
Correct Answer & Explanation
. Within 3-6 months
Explanation
For a primary radial nerve palsy associated with a closed humeral shaft fracture (neurapraxia or axonotmesis), the vast majority of patients (85-90%) will experience spontaneous recovery, typically beginning within 3-6 months. Observation for this period is the standard of care. If no signs of recovery are observed after 3-4 months, or if the palsy is iatrogenic or secondary (occurring after reduction), then surgical exploration may be indicated.
Question 9976
Topic: Surgical Anatomy & Approaches
Which of the following is an accepted indication for surgical exploration of the radial nerve in the context of a humeral shaft fracture?
Correct Answer & Explanation
. Incomplete radial nerve palsy that worsens after closed reduction
Explanation
An incomplete radial nerve palsy that worsens after closed reduction (or any manipulation) is a strong indication for surgical exploration. This suggests potential iatrogenic injury, nerve entrapment by fracture fragments or scar tissue, or progressive compression. Primary radial nerve palsy with closed fracture typically warrants observation for 3-6 months unless other surgical indications exist. Two weeks is too early to assess recovery. Sensory loss alone is usually observed. Radiographic evidence of entrapment is an indication, but option B is a more common and explicit trigger for exploration.
Question 9977
Topic: 1. General Principles & Basic Science
A 35-year-old female with severe unilateral hip dysplasia (Crowe Type IV) is scheduled for a primary THA. She has significant limb length discrepancy and a false acetabulum. Which of the following pre-operative planning steps is the most crucial to ensure a successful outcome and minimize complications?
Correct Answer & Explanation
. Detailed templating for both acetabular and femoral components, including potential osteotomies and graft requirements.
Explanation
Crowe Type IV dysplasia involves a high-riding femoral head and a dysplastic, shallow true acetabulum, often requiring a subtrochanteric osteotomy and/or extensive soft tissue release to bring the hip down. This scenario presents significant challenges in achieving limb length equality, restoring hip mechanics, and ensuring stable fixation. Detailed templating for both acetabular and femoral components is paramount. This includes planning for the placement of the acetabular component in the true anatomical acetabulum (often requiring medialization or grafting), determining the extent of potential limb lengthening (which is limited by sciatic nerve stretch tolerance), and planning for a subtrochanteric osteotomy if necessary to manage limb length and achieve proper hip center. While other options like MRI or CT are helpful, and tranexamic acid is standard, none are as critical as detailed templating for managing the specific complexities of Crowe IV dysplasia. Pre-stressing the limb with traction may give an estimate but doesn't replace meticulous templating for component sizing, placement, and osteotomy planning.
Question 9978
Topic: 1. General Principles & Basic Science
A 75-year-old female with chronic renal failure on hemodialysis presents with end-stage hip osteoarthritis and severe osteoporosis. She is scheduled for a THA. Which of the following is the most significant perioperative concern specific to this patient population?
Correct Answer & Explanation
. Challenges with fluid and electrolyte management and coagulopathy.
Explanation
Patients with chronic renal failure, especially those on hemodialysis, present unique and complex challenges for THA. While all the listed options are potential concerns, challenges with fluid and electrolyte management and coagulopathy aremost significant and specificto this population. Renal patients often have hyperkalemia, fluid overload, and metabolic acidosis, which need careful monitoring and management. Furthermore, they frequently have acquired platelet dysfunction and are often on anticoagulants for dialysis, leading to an increased risk of perioperative bleeding. While bone quality (osteoporosis and renal osteodystrophy) is a concern for fixation, and infection risk is elevated due to immunosuppression, the immediate life-threatening challenges often revolve around their metabolic and hematological derangements related to kidney function and dialysis. The risk of DVT can be high, but the combination of fluid/electrolyte and coagulopathy issues is particularly critical for managing these patients safely.
Question 9979
Topic: Infection, Pharmacology & VTE
A 75-year-old female with a history of diffuse idiopathic skeletal hyperostosis (DISH), Parkinson's disease, and previous right THA (now undergoing left THA) is identified as high risk for heterotopic ossification (HO). Which of the following is the most effective prophylactic measure against severe HO after THA?
Correct Answer & Explanation
. Oral NSAIDs for 6 weeks postoperatively.
Explanation
Patients with DISH, Parkinson's disease, and prior HO are at high risk for developing heterotopic ossification (HO) after THA. The two most effective prophylactic measures are NSAIDs and radiation therapy. For NSAIDs, a regimen of indomethacin 25 mg three times daily for 6 weeks is a common and effective protocol (B). A 1-week course (A) is generally insufficient for high-risk patients. For radiation, a single dose of 700-800 cGy (7-8 Gy) administered within 24-72 hours pre- or postoperatively to the affected hip is also highly effective (C). A dose of 2000 cGy (D) is too high and not standard for HO prophylaxis. Warfarin (E) is an anticoagulant and has no role in HO prophylaxis. Therefore, a 6-week course of NSAIDs is an appropriate and effective choice for high-risk patients.
Question 9980
Topic: Surgical Anatomy & Approaches
A 50-year-old male develops a foot drop immediately after primary total hip arthroplasty performed via a posterior approach. Clinical examination reveals weakness in ankle dorsiflexion and eversion, and sensory loss over the dorsum of the foot. What is the most likely injured nerve, and which factor is most commonly implicated in this type of injury?
Correct Answer & Explanation
. Sciatic nerve; limb lengthening exceeding 4 cm.
Explanation
Foot drop (weakness in ankle dorsiflexion and eversion) with sensory loss over the dorsum of the foot is the classic presentation of sciatic nerve palsy, specifically the peroneal division, which is more susceptible to stretch injury. The sciatic nerve (C) is at risk during a posterior approach due to direct trauma, thermal injury, or, most commonly, excessive limb lengthening. Limb lengthening exceeding 4 cm is a significant risk factor for sciatic nerve injury. The femoral nerve (A) is anterior. The obturator nerve (B) is medial. The lateral femoral cutaneous nerve (D) causes numbness in the lateral thigh (meralgia paresthetica). While the peroneal nerve (E) is affected, it's typically due to injury to its parent, the sciatic nerve, at the hip level, rather than isolated direct trauma during closure.
Test Yourself
Switch to an interactive, timed exam simulation to truly master this topic.