Hip, Shoulder & Trauma Orthopedic MCQs - Part 67

Question 1

In a patient undergoing a primary reverse total shoulder arthroplasty (rTSA) utilizing a classic Grammont-style prosthesis, how is the center of rotation of the glenohumeral joint altered compared to its native anatomical position to improve the biomechanical advantage of the deltoid muscle?

Explanation

The classic Grammont design for reverse total shoulder arthroplasty (rTSA) operates by medializing and distalizing the center of rotation of the shoulder joint. This structural shift recruits more fibers of the deltoid (specifically the anterior and posterior heads) and significantly increases its moment arm, allowing the deltoid to effectively substitute for a deficient rotator cuff in elevating the arm.

Question 2

A 68-year-old female presents with recurrent posterior dislocations of her total hip arthroplasty (THA). Radiographic and CT evaluation reveal a well-fixed, ingrown cementless femoral stem with 15 degrees of anteversion, and a well-fixed cementless acetabular component positioned in 10 degrees of retroversion and 45 degrees of abduction. The patient has good remaining bone stock. What is the most appropriate surgical intervention?

Explanation

The patient has a retroverted acetabular component (10 degrees of retroversion), which is a classic cause of posterior instability following THA. Native anatomy and typical THA targets aim for 15-20 degrees of cup anteversion. While constrained liners or dual-mobility cups are tools for instability, addressing the primary underlying malposition of the implant (the retroverted cup) via acetabular revision is the gold standard for long-term stability and prevention of impingement.

Question 3

A 35-year-old male sustains an acetabular fracture in a motor vehicle accident. Radiographs and CT imaging are obtained. According to the Letournel and Judet classification, which of the following specific radiographic or CT findings distinguishes a T-type fracture from a standard transverse fracture of the acetabulum?

Explanation

In the Letournel and Judet classification, a standard transverse fracture splits the acetabulum horizontally into a superior (iliac) and inferior (ischiopubic) segment, disrupting both the anterior and posterior columns. A T-type fracture is a transverse fracture with an added vertical split that extends inferiorly through the obturator ring, dividing the inferior segment into separate anterior and posterior pillars.

Question 4

Which of the following specific ligamentous disruptions is the primary distinguishing feature between an Anteroposterior Compression II (APC-II) and an Anteroposterior Compression III (APC-III) pelvic ring injury in the Young-Burgess classification?

Explanation

In the Young-Burgess classification, APC-II injuries involve a disrupted symphysis pubis (or vertical rami fractures) along with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, while the posterior sacroiliac ligaments remain intact (opening of the anterior SI joint). An APC-III injury involves the additional complete disruption of the posterior sacroiliac ligaments, leading to complete hemipelvic instability.

Question 5

During a Latarjet procedure for anterior shoulder instability, the coracoid process is osteotomized and transferred to the anterior glenoid. When retracting the conjoint tendon medially to expose the subscapularis, which nerve is at the highest risk of traction injury?

Explanation

The musculocutaneous nerve typically enters the deep surface of the coracobrachialis 5 to 8 cm distal to the coracoid process, though anatomic variations exist. During the Latarjet procedure, aggressive medial retraction of the conjoint tendon (short head of biceps and coracobrachialis) places the musculocutaneous nerve at significant risk for a traction neuropraxia.

Question 6

During the posterior approach to the hip (Kocher-Langenbeck), preservation of the blood supply to the femoral head is a critical consideration if the femoral head is to be retained. The deep branch of the medial femoral circumflex artery (MFCA) is protected primarily by which of the following intact structures?

Explanation

Anatomical studies by Gautier et al. demonstrated that the deep branch of the medial femoral circumflex artery (MFCA) runs posterior to the obturator externus tendon. Preserving the obturator externus during surgical dislocation or a posterior approach provides a protective barrier for the MFCA, which supplies the majority of blood to the femoral head.

Question 7

A 28-year-old male sustains a vertically oriented, highly displaced femoral neck fracture (Pauwels Type III). Which of the following internal fixation constructs provides the highest biomechanical stability against the high vertical shear forces inherent to this fracture pattern?

Explanation

Pauwels Type III fractures (>50 degrees to the horizontal) experience immense vertical shear forces rather than compressive forces. Multiple biomechanical studies have shown that a fixed-angle construct, such as a sliding hip screw (SHS), provides superior resistance to shear and varus collapse compared to parallel cancellous screws. A supplemental derotation screw is often added to control rotational forces.

Question 8

A 12-year-old overweight male presents with an atraumatic limp and left knee pain. An AP radiograph of the pelvis reveals a positive Trethowan sign. Which of the following defines a positive Trethowan sign in this context?

Explanation

The Trethowan sign is defined by Klein's line. Klein's line is drawn along the superior border of the femoral neck on an AP radiograph. In a normal hip, this line intersects the lateral portion of the capital femoral epiphysis. A positive Trethowan sign occurs when Klein's line does not intersect the epiphysis, highly indicative of a Slipped Capital Femoral Epiphysis (SCFE).

Question 9

According to Hertel's radiographic criteria, which combination of findings in an acute proximal humerus fracture carries the highest positive predictive value (up to 97%) for subsequent humeral head ischemia?

Explanation

Hertel et al. established that the risk of humeral head ischemia is greatest when there is a combination of an anatomical neck fracture (disrupting intraosseous supply), a short posteromedial metaphyseal head extension (calcar segment <8 mm), and disruption of the medial hinge (>2 mm displacement), indicating severe damage to the ascending branch of the anterior circumflex humeral artery and overall soft tissue envelope.

Question 10

A 24-year-old male is admitted after sustaining a closed tibial shaft fracture. Two hours later, he develops excruciating leg pain out of proportion to the injury and increased analgesic requirements. His blood pressure is 110/60 mmHg, and his mean arterial pressure (MAP) is 76 mmHg. Which of the following absolute intracompartmental pressure measurements, or derived calculations, is universally accepted as the most reliable threshold for diagnosing acute compartment syndrome and indicating urgent fasciotomy?

Explanation

The delta pressure (ΔP), defined as the diastolic blood pressure minus the intracompartmental pressure, is the most reliable objective metric for diagnosing acute compartment syndrome. A ΔP of less than or equal to 30 mm Hg indicates inadequate tissue perfusion and is the standard threshold for proceeding with emergent fasciotomies. Relying solely on absolute pressure numbers can lead to overtreatment in hypotensive or normal patients.

Question 11

In the pathogenesis of aseptic loosening secondary to ultra-high molecular weight polyethylene (UHMWPE) wear debris following a total hip arthroplasty, activated macrophages release inflammatory cytokines. Which specific receptor-ligand interaction is most directly responsible for driving the final common pathway of osteoclastogenesis and subsequent periprosthetic bone resorption?

Explanation

Macrophage phagocytosis of UHMWPE wear particles results in the release of TNF-α, IL-1, and IL-6. These cytokines stimulate osteoblasts and fibroblasts to express Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL). The binding of RANKL to the RANK receptor on osteoclast precursors drives their differentiation into mature osteoclasts, which resorb periprosthetic bone, leading to osteolysis.

Question 12

A 65-year-old male presents with severe shoulder weakness. MRI reveals a massive, retracted tear involving the supraspinatus and infraspinatus tendons with grade 3 fatty infiltration. Electromyography (EMG) indicates denervation changes in both muscles. Which anatomical site is the most likely location of secondary nerve tethering and traction injury caused directly by the medial retraction of these tendons?

Explanation

Massive medial retraction of the supraspinatus and infraspinatus muscles can exert a traction force on the suprascapular nerve. Because the nerve is relatively fixed at the suprascapular notch (under the transverse scapular ligament), medial retraction of the muscle belly causes the nerve to be stretched at this proximal anatomical tether point, leading to suprascapular neuropathy.

Question 13

A 40-year-old pedestrian is struck by a vehicle and sustains a Schatzker Type IV tibial plateau fracture. Which of the following best describes the typical pathomechanics of this specific fracture pattern and its most feared associated complication?

Explanation

A Schatzker Type IV fracture involves the medial tibial plateau. It typically results from a high-energy varus force combined with axial loading. Because the medial plateau is anatomically robust, fracturing it requires significant energy, which frequently disrupts the knee's ligamentous stability (often a fracture-dislocation) and carries a uniquely high risk of injury to the popliteal artery and common peroneal nerve due to stretching.

Question 14

In the evaluation of a 22-year-old hockey player with suspected femoroacetabular impingement (FAI), a specialized lateral radiograph of the hip (Dunn view) is obtained. Which of the following radiographic thresholds is generally accepted as diagnostic of a clinically significant Cam-type deformity?

Explanation

A Cam deformity represents an abnormal morphology of the proximal femur with decreased head-neck offset. The alpha angle, typically measured on a Dunn or cross-table lateral radiograph, quantifies this asphericity. An alpha angle greater than 50-55 degrees is considered diagnostic of a Cam lesion. A center-edge angle >40 degrees or a positive crossover sign suggests Pincer impingement.

Question 15

A 32-year-old male bodybuilder presents with acute pain, bruising, and a palpable defect in his anterior axilla after a heavy bench press. MRI confirms a complete rupture of the pectoralis major tendon. Based on normal anatomy, how does the sternocostal head of the pectoralis major typically insert onto the lateral lip of the bicipital groove relative to the clavicular head?

Explanation

The pectoralis major tendon undergoes a 180-degree twist before its insertion on the lateral lip of the bicipital groove. Consequently, the inferior fibers (the sternocostal head) twist upward and insert proximal and deep relative to the superior fibers (the clavicular head). This complex arrangement places the sternocostal head at maximal tension during the eccentric phase of a bench press, making it the most common site of failure.

Question 16

A 29-year-old male sustains a subtrochanteric femur fracture. On an anteroposterior radiograph, the proximal fragment exhibits a characteristic deformity consisting of flexion, abduction, and external rotation. Which muscle group is primarily responsible for the external rotation component of this deformity?

Explanation

In a subtrochanteric fracture, the proximal fragment is aggressively deformed by the muscles attaching to the greater and lesser trochanters. Flexion is driven by the iliopsoas (lesser trochanter), abduction is driven by the gluteus medius and minimus (greater trochanter), and external rotation is driven by the short external rotators (piriformis, gemelli, obturator internus/externus, quadratus femoris).

Question 17

According to the 2018 International Consensus Meeting (ICM) / Musculoskeletal Infection Society (MSIS) criteria for diagnosing periprosthetic joint infection (PJI), which of the following findings is considered a 'major' (absolute) criterion that essentially confirms a PJI?

Explanation

Under the widely accepted ICM/MSIS criteria, the presence of two 'major' criteria can independently definitively diagnose a PJI: (1) a sinus tract communicating with the prosthesis, or (2) two positive periprosthetic cultures with phenotypically identical organisms. Purulence, elevated ESR/CRP, elevated synovial WBC, and a single positive culture are considered 'minor' criteria, requiring a cumulative score to confirm the diagnosis.

Question 18

A 25-year-old male falls directly onto his right shoulder during a cycling accident. Radiographs reveal an acromioclavicular (AC) joint injury. According to the Rockwood classification, which of the following specific radiographic and anatomic findings distinguishes a Type V injury from a Type III injury?

Explanation

In the Rockwood classification of AC joint separations, a Type III injury involves disruption of both the AC and CC ligaments, resulting in up to 100% superior displacement of the clavicle relative to the acromion. A Type V injury is a much more severe form of Type III, characterized by 100% to 300% superior displacement, along with severe disruption/stripping of the deltotrapezial fascia, resulting in a dramatic clinical deformity.

Question 19

A 38-year-old male sustains a Hawkins Type II talar neck fracture and undergoes open reduction internal fixation (ORIF). At his 8-week postoperative visit, an AP radiograph of the ankle reveals a subchondral radiolucent band in the dome of the talus (Hawkins sign). What does this specific radiographic finding indicate?

Explanation

The Hawkins sign is a subchondral radiolucent band visible in the talar dome on an AP or mortise radiograph, typically seen 6 to 8 weeks after a talus fracture. It represents subchondral osteopenia secondary to bone resorption. Because this resorptive process requires an active blood supply, a positive Hawkins sign is a highly reassuring indicator that the talar body has sufficient vascularity and that clinically significant avascular necrosis (AVN) is unlikely.

Question 20

A 79-year-old female sustains a fall and presents with a periprosthetic fracture of the femur around a cemented total hip arthroplasty implanted 10 years ago. Radiographs show a transverse fracture at the tip of the stem. The cement mantle is extensively fractured, and the stem is frankly loose. However, cortical thickness in the proximal femur remains robust. According to the Vancouver classification, what is the fracture type and the most appropriate standard surgical management?

Explanation

The Vancouver classification for periprosthetic femur fractures defines a B2 fracture as being around or just below the stem tip with a loose implant, but with adequate remaining proximal bone stock. The standard of care for a Vancouver B2 fracture is revision arthroplasty using a long-stemmed prosthesis (often an extensively porous-coated or fluted tapered diaphyseal-engaging stem) that bypasses the fracture site by at least two cortical diameters to achieve stability. B1 is a stable stem (managed with ORIF), and B3 implies a loose stem with poor bone stock (often needing a proximal femoral replacement or allograft-prosthetic composite).

Question 21

Which patient or implant factor is most strongly associated with the complication of squeaking following a ceramic-on-ceramic (CoC) total hip arthroplasty?

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is strongly correlated with edge loading, typically due to acetabular cup malposition (such as excessive anteversion or vertical cup placement). This leads to stripe wear, loss of fluid-film lubrication, and subsequent micro-separation and noise generation. While younger age and high activity levels are clinical risk factors, mechanical edge loading from component malposition is the primary biomechanical cause.

Question 22

A 22-year-old competitive rugby player presents with recurrent anterior shoulder instability. A 3D CT scan reveals 25% anterior glenoid bone loss with a concomitant engaging Hill-Sachs lesion. What is the most appropriate surgical intervention to prevent recurrence?

Explanation

Critical anterior glenoid bone loss (generally defined as >20-25%) in a young, contact athlete with recurrent instability is best treated with a bony augmentation procedure. The open Latarjet procedure (coracoid transfer) addresses both the structural glenoid defect and provides a dynamic sling via the conjoint tendon. Arthroscopic Bankart alone has an unacceptably high failure rate in this setting. Remplissage is generally indicated for off-track engaging Hill-Sachs lesions when glenoid bone loss is subcritical (<20%).

Question 23

According to the criteria for borderline polytrauma patients, which of the following physiologic parameters most strongly favors the use of Damage Control Orthopedics (DCO) over Early Total Care (ETC) for the fixation of a bilateral femoral shaft fracture?

Explanation

Damage Control Orthopedics (DCO), which involves temporary external fixation prior to definitive internal fixation, is indicated in 'in extremis' or unstable polytrauma patients. Parameters favoring DCO include hypothermia (core temperature < 35°C), significant acidosis (pH < 7.24, base deficit > 6 mmol/L, lactate > 2.5 mmol/L), and coagulopathy (platelet count < 90,000/uL). A core temperature of 33.5°C reflects severe hypothermia, making the patient a poor candidate for the physiologic hit of prolonged early total care (ETC).

Question 24

In a patient with early-stage non-traumatic osteonecrosis of the femoral head, which of the following is considered the most reliable prognostic indicator for the success of a core decompression procedure?

Explanation

The success of core decompression in treating avascular necrosis (AVN) of the femoral head heavily depends on the size and location of the necrotic lesion, typically evaluated by the Kerboul angle or modified Steinberg/Ficat staging on MRI. Lesions involving <15% of the head and located medially or centrally have a significantly higher success rate than large, laterally located lesions. The presence of a crescent sign (Ficat stage III) indicates subchondral collapse and is generally considered a contraindication to core decompression.

Question 25

A 55-year-old patient undergoes a lower trapezius tendon transfer for an irreparable posterosuperior rotator cuff tear. To which anatomic footprint is the transferred tendon (or its allograft extension) classically attached to best restore external rotation?

Explanation

The lower trapezius tendon transfer is increasingly utilized for irreparable posterosuperior rotator cuff tears (involving the supraspinatus and infraspinatus) in patients without advanced arthropathy. Because the line of pull of the lower trapezius mimics that of the infraspinatus, the tendon (often elongated with an Achilles allograft) is attached to the infraspinatus footprint on the greater tuberosity to restore external rotation and assist with forward elevation.

Question 26

When treating a highly vertical (Pauwels type III) femoral neck fracture in a young adult, what is the primary biomechanical rationale for adding a fully threaded transverse 'position' screw to a standard construct of three parallel partially threaded cannulated screws?

Explanation

Vertically oriented (Pauwels type III) femoral neck fractures in young adults experience exceptionally high shear forces, predisposing them to varus collapse, nonunion, and failure. The addition of a fully threaded transverse 'position' screw (often placed inferiorly or centrally) crosses the fracture perpendicularly to the vertical shear plane. Unlike partially threaded lag screws, which can allow the fracture to slide excessively and shorten in vertical patterns, the fully threaded screw acts as a rigid dowel to resist inferior translation and varus collapse.

Question 27

A 45-year-old male sustains a complex acetabular fracture. CT imaging demonstrates a fracture of the anterior column with a posterior hemitransverse component, alongside a medially displaced quadrilateral plate. Which surgical approach provides the most direct and optimal access to reduce the quadrilateral plate and place an infrapectineal buttress plate?

Explanation

The modified Stoppa approach, an anterior intrapelvic approach, provides excellent visualization of the true pelvis, quadrilateral plate, posterior column, and pelvic brim. It is highly advantageous for treating anterior column/posterior hemitransverse fractures with medial displacement of the quadrilateral plate, as it directly allows the placement of an infrapectineal buttress plate to counteract the medial displacement. The Kocher-Langenbeck is posterior and does not allow direct plating of the medial quadrilateral surface.

Question 28

By which primary biomechanical mechanism does a Grammont-style reverse total shoulder arthroplasty (rTSA) restore active forward elevation in a patient with severe rotator cuff arthropathy?

Explanation

The classic Grammont reverse total shoulder arthroplasty design functions by medializing and distalizing the center of rotation of the glenohumeral joint. Medialization recruits more anterior and posterior deltoid fibers to assist in forward elevation, while distalization tensions the deltoid muscle, increasing its moment arm. This allows the deltoid to effectively compensate for the deficient rotator cuff.

Question 29

A 35-year-old female sustains a high-energy Schatzker type IV tibial plateau fracture extending into the medial metaphyseal-diaphyseal junction. Which of the following anatomical structures is at highest risk of severe injury due to this specific fracture pattern?

Explanation

Schatzker IV (medial plateau) fractures, especially those caused by high-energy trauma (e.g., varus force with axial load), are frequently associated with occult knee subluxation or dislocation. Because of the tethering of the popliteal artery at the adductor hiatus proximally and the soleal arch distally, it is at very high risk of stretch, intimal tear, or transection in medial plateau fractures. Thorough vascular evaluation (ABI, CTA if indicated) is mandatory.

Question 30

A 24-year-old male athlete presents with groin pain and is evaluated for femoroacetabular impingement (FAI). Which of the following radiographic findings is most specifically characteristic of Cam-type FAI?

Explanation

Cam-type FAI is caused by an aspherical femoral head-neck junction with loss of the normal waist, leading to abutment against the acetabular rim during flexion and internal rotation. This is quantified by the alpha angle, typically measured on a Dunn or cross-table lateral radiograph. An alpha angle >55 degrees is considered diagnostic for Cam morphology. Coxa profunda, increased center-edge angle, and crossover signs are indicative of Pincer-type FAI (acetabular overcoverage).

Question 31

During open reduction and internal fixation (ORIF) of a displaced 3-part proximal humerus fracture using a locking plate, failure to achieve which of the following technical goals most strongly predicts secondary varus collapse?

Explanation

Restoration of the medial hinge (calcar) is critical to the biomechanical stability of a proximal humerus fracture fixed with a locking plate. Failure to restore medial support—whether via direct cortical contact, placement of calcar screws in the inferomedial quadrant of the humeral head, or the use of an endosteal fibular strut allograft—is the strongest independent predictor of secondary varus collapse and subsequent screw cut-out into the joint.

Question 32

Regarding the evaluation of a mangled lower extremity and the decision between amputation and limb salvage, which of the following statements best reflects the findings of the Lower Extremity Assessment Project (LEAP) study?

Explanation

The landmark LEAP study demonstrated that traditional scoring systems (MESS, LSI, PSI) have low sensitivity and predictive value for determining the functional outcome of a mangled extremity. Furthermore, an initially insensate plantar foot does not preclude a good outcome with salvage, as sensation often returns. The study found no significant long-term difference in functional outcomes between the salvage and amputation groups, underscoring that no single score can dictate treatment; decisions must be highly individualized.

Question 33

In revision total hip arthroplasty, a 'jumbo' acetabular cup is occasionally utilized to manage large cavitary bone defects. Based on the widely accepted orthopedic literature definition, what minimal outer diameter constitutes a jumbo cup in male and female patients, respectively?

Explanation

In the context of revision total hip arthroplasty, a 'jumbo' cup is generally defined as an uncemented hemispherical acetabular shell with an outer diameter of ≥66 mm in males and ≥62 mm in females. These oversized cups maximize contact with host bone, achieving initial stability and promoting osseointegration across large cavitary defects without the absolute need for bulk allografts.

Question 34

A 19-year-old male is brought to the trauma bay following a high-speed motor vehicle collision with a diagnosed posterior sternoclavicular (SC) joint dislocation. He exhibits dyspnea, venous engorgement of the left arm, and dysphagia. Which specific anatomical structure is at greatest risk of direct compression by the displaced medial clavicle?

Explanation

Posterior sternoclavicular joint dislocations are orthopedic emergencies due to the proximity of the medial clavicle to critical mediastinal and superior thoracic outlet structures. The great vessels, particularly the brachiocephalic (innominate) and subclavian veins, lie immediately posterior to the SC joint. The subclavian vein is at highest risk for direct compression or laceration, which can present with venous engorgement of the ipsilateral upper extremity. The trachea and esophagus are also at risk, causing dyspnea and dysphagia.

Question 35

A 32-year-old male with a closed midshaft tibia fracture is suspected of developing acute compartment syndrome. His blood pressure is 110/70 mmHg. Intracompartmental pressure (ICP) monitoring is performed. According to the Delta P (ΔP) concept, at what threshold is emergent fasciotomy definitively indicated?

Explanation

The Delta P (ΔP) is defined as the difference between the diastolic blood pressure and the measured intracompartmental pressure (ΔP = Diastolic BP - ICP). A ΔP of less than 30 mmHg is the gold standard objective threshold indicating inadequate tissue perfusion, necessitating emergent fasciotomy. Absolute ICP values are less reliable due to variations in patient hemodynamics.

Question 36

A 12-year-old obese male presents with a stable, mild slipped capital femoral epiphysis (SCFE) of the left hip. Under which of the following circumstances is prophylactic in situ pinning of the contralateral, asymptomatic right hip most strongly indicated?

Explanation

While prophylactic pinning of the contralateral hip in SCFE remains controversial for idiopathic cases, it is strongly indicated in patients with underlying endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency). These patients have an extremely high risk (often >50-80%) of developing bilateral SCFE. Other relative indications for prophylactic pinning include younger age (e.g., girls <10, boys <12) and open triradiate cartilage (modified Oxford bone age).

Question 37

You are evaluating a 45-year-old polytrauma patient with a displaced extra-articular fracture of the scapular body and neck. Which of the following radiographic parameters is widely accepted as a standard indication for operative fixation of this scapula fracture?

Explanation

Operative indications for extra-articular scapular neck and body fractures include significant displacement that alters glenohumeral mechanics. Standard indications include medial/lateral displacement (translation) >20 mm, angular deformity >45 degrees, a glenopolar angle (GPA) of < 22 degrees (normal is 30-45 degrees), or a double disruption of the superior shoulder suspensory complex (SSSC).

Question 38

A 65-year-old female on long-term alendronate therapy sustains a low-energy subtrochanteric femur fracture. Radiographs show a transverse fracture with a medial cortical spike and lateral cortical thickening. During intramedullary nailing of this atypical femur fracture, what technical challenge must be anticipated compared to typical femur fractures?

Explanation

Atypical femur fractures (AFFs) associated with prolonged bisphosphonate use frequently occur in femurs with an increased anterolateral bow. Using standard, relatively straight intramedullary nails can result in an apex-anterior mismatch, leading to anterior cortical perforation or straightening of the fracture with lateral gap formation. Technical considerations include using a smaller radius of curvature (more bowed) nail, altering the starting point, or over-reaming to accommodate the anatomical mismatch.

Question 39

The direct anterior approach (Smith-Petersen) to the hip is favored by many due to its utilization of a true internervous and intermuscular plane. Which two nerves supply the muscles that form the superficial boundary of this surgical interval?

Explanation

The superficial interval of the direct anterior approach (Smith-Petersen) to the hip is between the sartorius and the tensor fasciae latae (TFL). The sartorius is innervated by the femoral nerve, and the TFL is innervated by the superior gluteal nerve, making it a true internervous plane. The deep interval is similarly internervous, between the rectus femoris (femoral nerve) and the gluteus medius/minimus (superior gluteal nerve).

Question 40

Following an arthroscopic rotator cuff repair, histological examination of the healing tendon-to-bone interface at 12 weeks primarily demonstrates which of the following?

Explanation

Unlike the native normal enthesis, which transitions smoothly through four zones (tendon, uncalcified fibrocartilage, calcified fibrocartilage, and bone) relying heavily on Type I collagen and Sharpey's fibers, surgically repaired rotator cuffs heal primarily by the formation of fibrovascular scar tissue. This scar tissue is mechanically inferior and consists predominantly of Type III collagen during the early and intermediate healing phases, which explains the inherent susceptibility to recurrent tears post-surgery.

Question 41

A 28-year-old male sustains a vertically oriented femoral neck fracture (Pauwels Type III) after a fall from a height. Which of the following fixation constructs provides the greatest biomechanical stability against vertical shear forces for this fracture pattern?

Explanation

A sliding hip screw (SHS) with a derotational screw provides superior biomechanical stability compared to multiple cannulated screws for high-shear, vertically oriented (Pauwels Type III) femoral neck fractures. This construct better resists the vertical shearing forces that commonly lead to failure and varus collapse in young patients.

Question 42

A 22-year-old rugby player presents with recurrent anterior shoulder instability. CT evaluation shows 22% anterior glenoid bone loss and a large Hill-Sachs lesion. Applying the glenoid track concept, which of the following confirms that the Hill-Sachs lesion is 'off-track'?

Explanation

A Hill-Sachs lesion is considered 'off-track' (engaging) when its intact medial margin extends medial to the medial boundary of the glenoid track. This occurs when the combination of glenoid bone loss and the size of the humeral head defect allows the lesion to engage the anterior glenoid rim during abduction and external rotation.

Question 43

A 45-year-old polytrauma patient arrives with a hemodynamically unstable anteroposterior compression (APC) Type III pelvic ring injury. In the trauma bay, a circumferential pelvic binder is applied. What is the optimal anatomic landmark for centering the pelvic binder to effectively reduce the pelvic volume?

Explanation

Circumferential pelvic binders should be centered over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placing the binder higher over the iliac crests is less effective and can paradoxically open the pelvis further or cause detrimental abdominal compression.

Question 44

A 55-year-old female with a metal-on-metal total hip arthroplasty presents with groin pain. Serum cobalt levels are elevated at 12 ppb, and MARS MRI reveals a solid pseudotumor compressing the femoral vein. What is the most appropriate surgical management?

Explanation

Symptomatic adverse local tissue reactions (ALTR/ALVAL) from metal-on-metal implants with elevated metal ions and pseudotumor require revision surgery. The bearing surface must be changed to eliminate the metal-on-metal articulation, typically utilizing a ceramic or metal head on a highly cross-linked polyethylene liner.

Question 45

A 76-year-old female sustains a displaced 4-part proximal humerus fracture. Radiographs demonstrate a disrupted medial calcar hinge with 3 mm of medial metaphyseal extension on the head fragment. She has pre-existing advanced rotator cuff arthropathy. What is the treatment of choice?

Explanation

Reverse total shoulder arthroplasty (rTSA) is the treatment of choice for elderly patients with complex 4-part proximal humerus fractures, disrupted medial hinges (high risk of avascular necrosis), and pre-existing rotator cuff dysfunction. rTSA relies on the deltoid for function and provides reliable pain relief and forward elevation.

Question 46

A 65-year-old male with a metal-on-polyethylene THA presents with groin pain and an enlarging cystic mass. Aspirate shows dark fluid, high cobalt and chromium levels, and negative infection markers. Pathology of the tissue shows ALVAL. What is the most likely source of this reaction?

Explanation

Trunnionosis occurs at the modular head-neck junction, leading to mechanically assisted crevice corrosion and ALVAL, even in metal-on-polyethylene bearings. High serum or fluid cobalt levels with a pseudotumor are characteristic.

Question 47

In a 72-year-old patient with a 4-part proximal humerus fracture undergoing reverse total shoulder arthroplasty, the tuberosities are repaired around the prosthesis. Which factor is most critical for tuberosity healing and optimizing postoperative external rotation?

Explanation

Anatomic restoration of humeral height and retrotorsion tension the rotator cuff properly. This prevents excessive stress on the repair, optimizing tuberosity healing and subsequent external rotation.

Question 48

A 28-year-old male sustains a vertical, Pauwels type III femoral neck fracture. To biomechanically optimize fixation and reduce the risk of shear-induced varus collapse, which construct is most appropriate?

Explanation

Pauwels type III fractures have high vertical shear forces. A fixed-angle device like a sliding hip screw, supplemented with a derotation screw, provides superior biomechanical resistance to varus collapse compared to parallel cancellous screws.

Question 49

A 24-year-old athlete undergoes hip arthroscopy for cam-type FAI. Postoperatively, he develops profound weakness in hip flexion and a small area of numbness on the anteromedial thigh. Which portal placement most likely caused this nerve injury?

Explanation

The mid-anterior portal places branches of the lateral femoral cutaneous nerve at risk. Deep dissection placed too medially can endanger the femoral nerve, leading to hip flexion weakness and saphenous nerve distribution numbness.

Question 50

During open reduction and internal fixation of a posterior wall acetabular fracture via a Kocher-Langenbeck approach, the surgeon utilizes the "safe zone" for hardware placement to avoid intra-articular screw penetration. What defines the borders of this safe zone?

Explanation

The safe zone for screw placement in the posterior acetabulum extends from the gluteus medius pillar cranially to the ischial spine caudally. Placing screws parallel to the quadrilateral plate within this zone avoids articular penetration.

Question 51

A 62-year-old male presents with chronic insidious shoulder pain and stiffness 18 months after an anatomic total shoulder arthroplasty. Inflammatory markers (ESR, CRP) are normal. Preoperative aspiration grows Cutibacterium acnes after 10 days of incubation. What is the most appropriate management?

Explanation

Chronic periprosthetic joint infections of the shoulder, particularly with C. acnes, are definitively managed with a two-stage revision using an antibiotic spacer. This approach provides the most reliable eradication of the biofilm.

Question 52

A 78-year-old female sustains an unstable intertrochanteric fracture with a large posteromedial fragment and loss of the lateral wall. Which of the following fixation devices is most appropriate to prevent excessive sliding and medialization of the femoral shaft?

Explanation

In unstable intertrochanteric fractures with lateral wall incompetence, a sliding hip screw allows excessive sliding and medial displacement of the shaft. A cephalomedullary nail acts as an intact lateral buttress, preventing this mechanical failure.

Question 53

A 22-year-old rugby player has recurrent anterior shoulder instability. CT scan reveals anterior glenoid bone loss of 25%. Which procedure provides the lowest recurrence rate for this patient?

Explanation

Critical glenoid bone loss (>20-25%) in a contact athlete is best managed with a bony augmentation procedure like the Latarjet. Soft tissue repairs alone in this setting have an unacceptably high failure rate.

Question 54

During a direct anterior approach for a total hip arthroplasty, the surgeon dissects between the tensor fasciae latae and the sartorius. Which vessel must typically be identified and ligated within this interval to prevent postoperative hematoma?

Explanation

The direct anterior approach utilizes the Smith-Petersen internervous plane. The ascending branches of the lateral femoral circumflex artery cross this interval and must be ligated to prevent excessive bleeding.

Question 55

A 30-year-old polytrauma patient presents with a severe closed midshaft femur fracture, bilateral rib fractures, and a pulmonary contusion. Serum lactate is 4.5 mmol/L and base deficit is -8. What is the most appropriate initial management of the femur fracture?

Explanation

This patient is in physiological extremis (high lactate, high base deficit) with significant chest trauma. Damage control orthopedics utilizing rapid external fixation is indicated to minimize the inflammatory "second hit" from intramedullary nailing.

Question 56

When preparing the glenoid for an anatomic total shoulder arthroplasty, a surgeon notes a Walch B2 morphology. What defines a B2 glenoid, and what is the primary risk if it is not corrected?

Explanation

A Walch B2 glenoid features a biconcave surface and posterior bone loss with retroversion. Uncorrected B2 wear leads to eccentric edge-loading, posterior subluxation, and early glenoid component loosening.

Question 57

Increasing the femoral head size from 28 mm to 36 mm in a total hip arthroplasty has which of the following biomechanical effects?

Explanation

A larger femoral head size increases the jump distance and the head-to-neck ratio, improving range of motion and joint stability. However, it increases the sliding distance per step, leading to higher volumetric polyethylene wear.

Question 58

A 45-year-old male sustains a Schatzker type VI tibial plateau fracture. He is scheduled for dual-plate fixation. Which principle is most critical to minimize the risk of wound complications and deep infection?

Explanation

High-energy tibial plateau fractures (Schatzker VI) cause severe soft-tissue compromise. Delaying definitive open reduction until the "wrinkle sign" appears significantly reduces the incidence of wound dehiscence and deep infection.

Question 59

A 55-year-old female presents with a massive, retracted, immobile tear of the supraspinatus and infraspinatus. Fatty infiltration is Goutallier stage 3. She exhibits pseudoparalysis of elevation. What is the most reliable surgical option to restore active elevation?

Explanation

In an older patient with a massive, irreparable rotator cuff tear, significant fatty infiltration (Goutallier 3), and pseudoparalysis, a reverse total shoulder arthroplasty provides the most reliable functional restoration.

Question 60

A 68-year-old male presents with severe hip pain and fever 2 weeks after a primary THA. Aspiration yields purulent fluid. Debridement, antibiotics, and implant retention (DAIR) is planned. Which intraoperative step is mandatory to maximize success?

Explanation

During a DAIR procedure for acute periprosthetic joint infection, exchanging all modular components (head and liner) is critical to access the entire joint space, debride necrotic tissue, and physically reduce the biofilm burden.

Question 61

A 25-year-old cyclist falls directly onto his shoulder and sustains a completely displaced midshaft clavicle fracture with 2.5 cm of shortening. Compared to operative fixation, nonoperative management of this specific fracture pattern is associated with which outcome?

Explanation

Completely displaced midshaft clavicle fractures with significant shortening (>2 cm) have significantly higher rates of symptomatic nonunion and delayed union when managed nonoperatively compared to primary open reduction and internal fixation.

Question 62

A 32-year-old patient on chronic corticosteroids develops Ficat Stage II avascular necrosis of the femoral head. There is no subchondral collapse on plain radiographs, but MRI shows necrosis involving 40% of the weight-bearing area. Which treatment is most indicated?

Explanation

Ficat Stage II AVN (pre-collapse with reactive radiographic changes) is the classic indication for head-preserving procedures like core decompression. This reduces intraosseous pressure and aims to stimulate revascularization.

Question 63

An APC-III (Anteroposterior Compression Type III) pelvic ring injury is characterized by complete disruption of the symphysis pubis and which of the following posterior ligamentous complexes?

Explanation

An APC-III injury involves complete anterior and posterior disruption. This includes the symphysis pubis, the sacrotuberous/sacrospinous ligaments, and both the anterior and posterior sacroiliac ligaments, leading to complete global instability.

Question 64

Following an open Latarjet procedure, the patient complains of an inability to actively flex the elbow and numbness along the lateral aspect of the forearm. Which nerve was most likely injured by excessive retraction of the conjoint tendon?

Explanation

The musculocutaneous nerve enters the coracobrachialis 5-8 cm distal to the coracoid process. Excessive medial retraction of the conjoint tendon during a Latarjet can stretch this nerve, causing weak elbow flexion and lateral forearm numbness.

Question 65

A 40-year-old male sustains a posterior hip dislocation with an associated Pipkin Type II femoral head fracture. After closed reduction, CT confirms a displaced, large superior head fragment. What is the most appropriate surgical management?

Explanation

Pipkin Type II fractures involve the weight-bearing dome cephalad to the fovea. Displaced fragments require ORIF. An anterior approach (Smith-Petersen) or surgical dislocation provides optimal visualization of the superior femoral head for anatomic fixation.

Question 66

A 65-year-old male undergoes a reverse total shoulder arthroplasty (rTSA). Preoperatively, he had an irreparable massive rotator cuff tear involving the supraspinatus, infraspinatus, and teres minor, presenting clinically with a positive hornblowers sign. Which of the following concomitant procedures is most appropriate to perform during the rTSA to optimize his postoperative function?

Explanation

Patients with combined loss of active elevation and external rotation (CLEER) and a positive hornblowers sign (teres minor deficiency) benefit from a latissimus dorsi or lower trapezius transfer combined with rTSA to restore external rotation.

Question 67

A 55-year-old male with a history of a metal-on-polyethylene total hip arthroplasty utilizing a large-diameter modular cobalt-chromium femoral head presents with groin pain and swelling. Aspiration yields sterile fluid. Laboratory tests reveal significantly elevated serum cobalt levels with normal chromium levels. MRI demonstrates a solid and cystic soft-tissue mass around the hip. What is the most likely pathophysiologic mechanism for this presentation?

Explanation

The differential elevation of cobalt over chromium in a metal-on-polyethylene THA indicates mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction. This leads to an adverse local tissue reaction (ALTR) or pseudotumor.

Orthopedic Surgery MCQs: Arthroplasty, Fracture & Hip Exam Prep | Part 18

Orthopedic Board Review MCQs: Hip, Shoulder & Trauma | Part 67

Key Takeaway

Orthopedic Board Review MCQs: Hip, Shoulder & Trauma | Part 67

Chapter Index