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1. General Principles & Basic Science MCQs

Practice Set 389 of 789

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 7761

Topic: Surgical Anatomy & Approaches

During an anterior (Smith-Petersen) approach to the hip, a true internervous plane is utilized. Proximally, this surgical interval is developed between muscles innervated by which two nerves?

. Femoral nerve and Superior gluteal nerve
. Femoral nerve and Obturator nerve
. Superior gluteal nerve and Inferior gluteal nerve
. Obturator nerve and Sciatic nerve
. Femoral nerve and Sciatic nerve

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

The proximal internervous plane for the Smith-Petersen approach is between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). Distally, the plane falls between the rectus femoris and gluteus medius.

Question 7762

Topic: 1. General Principles & Basic Science

During the distal extent of the volar (Henry) approach to the radius, the pronator quadratus must be elevated to visualize the volar cortex. To maintain its blood supply and allow for an adequate repair at closure, from which border should the muscle be detached?

. Medial border of the ulna
. Lateral border of the radius
. Proximal border
. Distal border
. Volar mid-substance

Correct Answer & Explanation

. Lateral border of the radius

Explanation

The pronator quadratus is supplied by the anterior interosseous artery, which enters the muscle proximally and dorsally. It should be elevated subperiosteally from the lateral border of the radius and reflected medially toward the ulna to preserve its neurovascular pedicle.

Question 7763

Topic: Surgical Anatomy & Approaches

A 22-year-old rugby player undergoes an open Latarjet procedure for recurrent anterior shoulder instability with 25% glenoid bone loss. Postoperatively, he presents with profound weakness with shoulder abduction and absent sensation over the lateral aspect of the shoulder. Which nerve was most likely injured, and what is its pertinent anatomic relationship during the procedure?

. Axillary nerve, passing inferior to the subscapularis and shoulder capsule
. Musculocutaneous nerve, entering the conjoint tendon distally
. Suprascapular nerve, passing through the spinoglenoid notch
. Radial nerve, passing through the triangular interval
. Spinal accessory nerve, coursing deep to the trapezius

Correct Answer & Explanation

. Axillary nerve, passing inferior to the subscapularis and shoulder capsule

Explanation

The patient's presentation of deltoid weakness and lateral shoulder numbness indicates an axillary nerve injury. During a Latarjet procedure, the axillary nerve is at risk during the inferior capsular release and subscapularis split/tenotomy, as it courses closely inferior to the subscapularis and capsule to enter the quadrangular space.

Question 7764

Topic: 1. General Principles & Basic Science

A 45-year-old woman experiences a painful pop in the posterior aspect of her knee while descending stairs. MRI demonstrates a complete radial tear of the posterior root of the medial meniscus with 3 mm of meniscal extrusion. If this injury is left untreated, the knee joint contact mechanics will most closely resemble which of the following conditions?

. Total medial meniscectomy
. Partial medial meniscectomy
. Isolated ACL deficiency
. Normal native knee mechanics
. Medial collateral ligament (MCL) deficiency

Correct Answer & Explanation

. Total medial meniscectomy

Explanation

A complete radial tear at the posterior root of the medial meniscus completely disrupts the circumferential hoop stresses of the meniscus. Biomechanical studies have demonstrated that this effectively renders the meniscus non-functional, resulting in joint contact pressures and areas equivalent to those seen in a knee that has undergone a total medial meniscectomy.

Question 7765

Topic: Biomechanics & Biomaterials

A 35-year-old competitive weightlifter presents to the emergency department with acute severe pain, swelling, and ecchymosis over the right anterior axilla and medial arm. He reports feeling a sudden 'tearing' sensation at the bottom phase of a maximal bench press. Physical examination demonstrates a notable loss of the anterior axillary contour. Based on the biomechanics of this injury pattern, which portion of the pectoralis major muscle is placed under the greatest tension during this movement and most commonly ruptures first?

. The clavicular head near its sternal origin
. The sternal head at the musculotendinous junction
. The sternal head at its humeral insertion
. The clavicular head at its humeral insertion
. The abdominal head near its rectus sheath fascial origin

Correct Answer & Explanation

. The sternal head at its humeral insertion

Explanation

Pectoralis major tendon ruptures classically occur in weightlifters performing the bench press, and the most common location of failure is at the humeral insertion (tendon avulsion). The pectoralis major tendon undergoes a complex 180-degree twist before inserting on the humerus, such that the inferior (sternocostal/sternal) fibers insert most superiorly and proximally. When the arm is in maximum extension, abduction, and external rotation (the lowest point of the bench press), these inferior sternal fibers are stretched maximally. Thus, the sternal head at its humeral insertion undergoes the highest disproportionate tension and is consistently the first portion to fail.

Question 7766

Topic: Biomechanics & Biomaterials

During the arthroscopic repair of a Type II Superior Labrum Anterior to Posterior (SLAP) tear in a 21-year-old collegiate baseball pitcher, anchors are placed to secure the labrum. To avoid altering the complex biomechanics of the superior labrum and to minimize postoperative stiffness, anchor placement should strictly avoid which of the following areas?

. Posterior to the biceps root
. Anterior to the biceps root
. Directly through the biceps anchor
. At the 10 o'clock position of the glenoid
. At the 11 o'clock position of the glenoid

Correct Answer & Explanation

. Posterior to the biceps root

Explanation

In repairing a Type II SLAP lesion, anchors should be placed posterior to the biceps anchor (and sometimes anteriorly if the tear extends into that region) but NEVER directly through or securing the biceps tendon root itself. Tying down the biceps anchor directly restricts its normal physiologic rolling and excursion during overhead motions, which consistently leads to severe postoperative stiffness, particularly in overhead throwing athletes.

Question 7767

Topic: Physiology & Rehabilitation

A 24-year-old recreational soccer player sustains an acute anterior cruciate ligament (ACL) rupture. During a subsequent gait analysis assessment, which of the following kinematic adaptations is most characteristic of a classic ACL-deficient 'quadriceps avoidance gait' during the stance phase?

. Increased peak knee flexion angle
. Decreased peak knee flexion to minimize anterior tibial translation
. Increased internal rotation of the tibia
. Excessive varus thrust during mid-stance
. Prolonged heel strike phase

Correct Answer & Explanation

. Decreased peak knee flexion to minimize anterior tibial translation

Explanation

Patients with an ACL-deficient knee often adopt a 'quadriceps avoidance gait' to dynamically stabilize the knee. Because contraction of the quadriceps pulls the tibia anteriorly, the patient unconsciously decreases peak knee flexion during the stance phase, relying more on hip extensors and hamstrings to prevent the tibia from subluxating anteriorly.

Question 7768

Topic: 1. General Principles & Basic Science

A 28-year-old bodybuilder feels a tearing sensation in his anterior chest while performing a heavy bench press. Examination reveals a loss of the anterior axillary fold and significant weakness with internal rotation. Which portion of the pectoralis major is most commonly injured in this mechanism, and what is its anatomic footprint on the humerus?

. Clavicular head; inserts deep and superior to the sternal head
. Sternal head; inserts deep and superior to the clavicular head
. Sternal head; inserts superficial and inferior to the clavicular head
. Clavicular head; inserts superficial and inferior to the sternal head
. Abdominal head; inserts directly onto the coracoid process

Correct Answer & Explanation

. Sternal head; inserts deep and superior to the clavicular head

Explanation

Pectoralis major ruptures most commonly occur at the musculotendinous junction or tendinous insertion of the sternocostal (sternal) head during an eccentric contraction, such as a heavy bench press. The anatomy of the pectoralis major tendon is unique: the tendon twists 180 degrees before inserting on the lateral lip of the bicipital groove. Because of this twist, the lower (sternal) fibers insert superior and deep to the upper (clavicular) fibers.

Question 7769

Topic: 1. General Principles & Basic Science

A 28-year-old competitive bodybuilder sustains an acute injury to his chest while performing a heavy bench press. Examination reveals ecchymosis over the anterior axillary fold and a palpable defect. Which of the following correctly describes the most common anatomic location and tissue involved in this injury?

. Muscle belly tear of the clavicular head
. Muscle-tendon junction tear of the clavicular head
. Tendon avulsion of the sternocostal head from the humerus
. Tendon avulsion of the clavicular head from the humerus
. Bony avulsion of the sternocostal head from the sternum

Correct Answer & Explanation

. Tendon avulsion of the clavicular head from the humerus

Explanation

Pectoralis major ruptures most commonly occur during weightlifting (e.g., bench press). The most common pattern is an avulsion of the tendon of the sternocostal head from its insertion on the humerus. The sternocostal head is under maximal tension when the arm is extended, abducted, and externally rotated (the bottom of a bench press).

Question 7770

Topic: Physiology & Rehabilitation

A 16-year-old male sprinter feels a sudden 'pop' and experiences severe pain in his buttock during a 100-meter dash. Radiographs demonstrate an avulsion fracture of the ischial tuberosity with 3.5 cm of displacement. Which of the following muscles or muscle groups is primarily responsible for the displacement of this fracture?

. Rectus femoris
. Sartorius
. Hamstrings
. Iliopsoas
. Gluteus maximus

Correct Answer & Explanation

. Hamstrings

Explanation

The ischial tuberosity is the anatomic origin of the hamstring muscle complex (long head of the biceps femoris, semitendinosus, and semimembranosus). An avulsion fracture of the ischial tuberosity in a skeletally immature athlete is typically caused by a sudden, forceful eccentric contraction of the hamstrings. The rectus femoris originates at the AIIS, the sartorius at the ASIS, and the iliopsoas inserts at the lesser trochanter.

Question 7771

Topic: 1. General Principles & Basic Science

A 28-year-old weightlifter feels a sharp "pop" and tearing sensation in his anterior axilla while performing a heavy bench press. Physical examination reveals loss of the anterior axillary fold and weakness in internal rotation. Operative exploration is planned. Which portion of the pectoralis major is most commonly injured in this scenario, and what is its correct anatomic insertion on the humerus relative to the other head?

. Clavicular head; inserts proximal and anterior to the sternal head
. Clavicular head; inserts distal and posterior to the sternal head
. Sternal head; inserts proximal and anterior to the clavicular head
. Sternal head; inserts proximal and posterior to the clavicular head
. Sternal head; inserts distal and posterior to the clavicular head

Correct Answer & Explanation

. Sternal head; inserts proximal and posterior to the clavicular head

Explanation

The pectoralis major tendon undergoes a 180-degree twist before inserting onto the lateral lip of the bicipital groove. Because of this twist, the lower (sternal) fibers insert most proximally and posteriorly, while the upper (clavicular) fibers insert distally and anteriorly. The sternal head is under maximal tension when the arm is extended and abducted (such as at the bottom of a bench press) and is therefore the most commonly ruptured segment in weightlifting injuries.

Question 7772

Topic: Biomechanics & Biomaterials

A 23-year-old elite collegiate baseball pitcher is undergoing ulnar collateral ligament (UCL) reconstruction using a palmaris longus autograft. To accurately reproduce the kinematics of the native UCL and restore valgus stability, the surgeon must precisely locate the anatomic footprints. Which of the following accurately describes the anatomic insertion of the anterior bundle of the UCL on the ulna?

. It inserts as a distinct focal point exclusively on the tip of the sublime tubercle, 2 mm distal to the joint line
. It inserts broadly along the medial olecranon, 5 mm distal to the joint line
. It inserts on the sublime tubercle and extends distally along the ulnar ridge an average of 18 mm
. It inserts 2 mm proximal to the joint line on the coronoid process
. It inserts deep to the flexor carpi ulnaris, tapering towards the supinator crest

Correct Answer & Explanation

. It inserts on the sublime tubercle and extends distally along the ulnar ridge an average of 18 mm

Explanation

The anterior bundle of the UCL is the primary restraint to valgus stress at the elbow. Anatomic studies (such as those by Dugas et al.) have demonstrated that the ulnar footprint of the anterior bundle is not merely a single point at the sublime tubercle but rather a broad insertion that begins near the sublime tubercle and tapers distally along the ulnar ridge for an average length of approximately 18 mm. Recognizing this broad, tapering footprint is critical for proper tunnel placement and graft tensioning during reconstruction.

Question 7773

Topic: 1. General Principles & Basic Science

Based on recent Level I randomized controlled trials comparing operative and non-operative management of acute Achilles tendon ruptures using early functional rehabilitation protocols, which of the following outcomes remains significantly higher in the non-operative group?

. Rate of deep vein thrombosis (DVT)
. Sural nerve injury
. Long-term functional deficit in plantar flexion power
. Rate of re-rupture
. Time to return to sport

Correct Answer & Explanation

. Rate of re-rupture

Explanation

Recent high-level evidence, including the landmark RCT by Willits et al., demonstrated that when aggressive early functional rehabilitation protocols are utilized, there is no clinically significant difference in functional outcomes, range of motion, or time to return to work/sport between operative and non-operative management of acute Achilles tendon ruptures. However, the re-rupture rate, while lower than historical cast-immobilization cohorts, still remains slightly higher in the non-operative group. Operative management inherently carries risks of surgical site infection and sural nerve injury.

Question 7774

Topic: 1. General Principles & Basic Science

A 45-year-old female sustains an acute posterior root tear of the medial meniscus. Biomechanically, what is the consequence on contact pressures in the medial compartment if this tear is left untreated, compared to a totally meniscectomized knee?

. Contact pressures increase to levels equivalent to a total medial meniscectomy
. Contact pressures remain similar to an intact meniscus, but shear forces increase
. Contact pressures are approximately 50% less than a total meniscectomy
. Contact pressures paradoxically decrease due to compensatory lateral shift
. Contact area increases, which limits the rise in contact pressures

Correct Answer & Explanation

. Contact pressures increase to levels equivalent to a total medial meniscectomy

Explanation

A posterior root tear of the medial meniscus disrupts the circumferential hoop fibers, resulting in catastrophic failure of the meniscus to distribute axial loads. This leads to meniscal extrusion. Biomechanical studies have conclusively shown that a posterior root tear is functionally and biomechanically equivalent to a total medial meniscectomy, significantly decreasing the contact area and increasing peak contact pressures by over 200%.

Question 7775

Topic: 1. General Principles & Basic Science

A 28-year-old competitive powerlifter felt a sudden tearing sensation in his anterior chest wall while performing a heavy bench press. Examination reveals loss of the normal anterior axillary fold and weakness in internal rotation.

Which portion of the affected tendon is most commonly ruptured during this activity, and what is its normal anatomic insertion relative to the other heads?

. Clavicular head, inserting deep and proximal on the humerus
. Clavicular head, inserting superficial and distal on the humerus
. Sternal head, inserting deep and proximal on the humerus
. Sternal head, inserting superficial and distal on the humerus
. Abdominal head, inserting deep and proximal on the humerus

Correct Answer & Explanation

. Sternal head, inserting deep and proximal on the humerus

Explanation

Pectoralis major ruptures most commonly occur during eccentric loading (e.g., bench pressing) and typically involve the sternocostal head. Due to the 180-degree twist of the pectoralis major tendon as it travels to its insertion on the lateral lip of the bicipital groove, the inferiorly originating sternal head fibers insert proximal and deep to the superiorly originating clavicular head fibers.

Question 7776

Topic: Surgical Anatomy & Approaches

A 22-year-old professional rugby player undergoes a Latarjet procedure for recurrent anterior shoulder instability with 25% glenoid bone loss. Postoperatively, he exhibits weakness in initiating shoulder abduction and decreased sensation over the lateral aspect of the proximal arm. Which nerve was most likely injured during the procedure?

. Musculocutaneous nerve
. Axillary nerve
. Suprascapular nerve
. Radial nerve
. Median nerve

Correct Answer & Explanation

. Axillary nerve

Explanation

The axillary nerve is at high risk during the Latarjet procedure, particularly during the exposure of the inferior glenoid and capsular release. It innervates the deltoid (shoulder abduction) and provides sensation to the lateral arm via the superior lateral cutaneous nerve of the arm. The musculocutaneous nerve is also at risk during coracoid preparation and transfer, but injury would present with biceps weakness and lateral forearm sensory deficits.

Question 7777

Topic: Physiology & Rehabilitation

A 32-year-old male powerlifter feels a sudden 'pop' in his chest while performing a heavy bench press. Examination reveals an asymmetric loss of the anterior axillary fold and weakness in internal rotation and adduction of the shoulder. MRI confirms a complete rupture of the pectoralis major. Where is the most common anatomical site of rupture for this injury?

. Muscle belly
. Musculotendinous junction
. Sternal origin
. Clavicular origin
. Distal tendon at the humeral insertion

Correct Answer & Explanation

. Distal tendon at the humeral insertion

Explanation

Pectoralis major ruptures most commonly occur during forceful eccentric contraction, such as the lowering phase of a bench press. The most common location of the tear is an avulsion of the distal tendon from its insertion site on the lateral lip of the bicipital groove of the proximal humerus. Surgical repair is generally recommended for complete ruptures at the insertion in active individuals.

Question 7778

Topic: Biomechanics & Biomaterials

A 45-year-old active female reports feeling a 'pop' in the back of her knee while squatting to pick up a box, followed by posterior knee pain and mild effusion. MRI demonstrates a complete radial tear of the posterior root of the medial meniscus with 4 mm of medial meniscal extrusion. Biomechanical studies have shown that if this injury is left untreated, it alters knee joint contact mechanics to most closely resemble which of the following conditions?

. Intact knee biomechanics due to capsular healing
. Total medial meniscectomy
. Isolated ACL deficiency
. Patellofemoral osteoarthritis
. Total lateral meniscectomy

Correct Answer & Explanation

. Total medial meniscectomy

Explanation

A complete medial meniscus posterior root tear severely disrupts the hoop stresses of the meniscus, rendering it biomechanically incompetent. In cadaveric studies, a complete root tear has been shown to lead to peak contact pressures and decreased contact area in the medial compartment that are equivalent to those seen in a total medial meniscectomy. This results in rapid progression of medial compartment osteoarthritis if not surgically repaired in suitable candidates.

Question 7779

Topic: Physiology & Rehabilitation

A 28-year-old male bodybuilder feels a sudden, painful pop in his right anterior chest wall while performing a heavy bench press. Examination reveals an asymmetric chest wall with a palpable defect medial to the axillary fold, and profound weakness with adduction and internal rotation of the arm. Which of the following best describes the typical anatomic site and mechanism of the majority of these injuries?

. Avulsion of the clavicular head from the humerus during eccentric contraction
. Avulsion of the sternocostal head from the humerus during eccentric contraction
. Midsubstance tear of the sternocostal head during concentric contraction
. Rupture at the musculotendinous junction of the clavicular head during concentric contraction
. Avulsion of the sternocostal head from the sternum during eccentric contraction

Correct Answer & Explanation

. Avulsion of the sternocostal head from the humerus during eccentric contraction

Explanation

The pectoralis major is most commonly injured during maximal eccentric contraction, such as the eccentric lowering phase of a bench press. The sternocostal head is typically the most frequently injured portion due to its mechanical disadvantage at the inferior aspect of the tendon footprint. Ruptures most commonly occur as tendon avulsions from the humeral insertion or at the musculotendinous junction. Early surgical repair is indicated for complete tears in active individuals.

Question 7780

Topic: 1. General Principles & Basic Science

A 50-year-old active female feels a pop in the posterior aspect of her knee while squatting. MRI reveals a medial meniscus posterior root tear with 3 mm of meniscal extrusion. Which of the following biomechanical consequences is most directly associated with this specific injury if left untreated?

. Loss of the 'screw-home' mechanism during terminal knee extension
. Decreased peak contact pressures in the medial compartment
. Biomechanical equivalence to a total medial meniscectomy
. Increased anterior tibial translation during the Lachman test
. Shift of the mechanical axis into valgus

Correct Answer & Explanation

. Decreased peak contact pressures in the medial compartment

Explanation

A medial meniscus posterior root tear disrupts the hoop stresses of the meniscus, rendering it biomechanically equivalent to a total meniscectomy. This leads to an inability to convert axial loads into circumferential tension, resulting in significantly increased peak contact pressures in the medial compartment, medial joint space narrowing, and rapid progression to osteoarthritis.

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