This practice set contains high-yield board review questions covering key concepts in 2. Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 10361
Topic: 2. Trauma
A 70-year-old female on long-term bisphosphonate therapy sustains a minimal-trauma subtrochanteric femur fracture. Which radiographic feature is classically associated with this specific type of atypical femur fracture?
Correct Answer & Explanation
. Medial cortical spiking
Explanation
Atypical femur fractures related to long-term bisphosphonate use characteristically exhibit lateral cortical thickening (beaking) and a transverse or short oblique fracture line that originates on the lateral tension side.
Question 10362
Topic: 2. Trauma
The primary vascular supply to the proximal pole of the scaphoid enters the bone at which of the following anatomical locations?
Correct Answer & Explanation
. Volar surface, proximal to the waist
Explanation
The primary blood supply to the scaphoid is from the radial artery. The major vessels enter the bone along the dorsal ridge, which is distal to the scaphoid waist. The blood supply to the proximal pole is entirely retrograde, which explains the high rate of avascular necrosis and nonunion in proximal pole fractures.
Question 10363
Topic: 2. Trauma
In a direct lateral approach to the fibula for open reduction and internal fixation of a lateral malleolus fracture, the superficial peroneal nerve must be protected. At approximately what distance proximal to the tip of the lateral malleolus does this nerve typically pierce the deep crural fascia to become subcutaneous?
Correct Answer & Explanation
. 2 cm
Explanation
The superficial peroneal nerve typically pierces the deep crural fascia to become subcutaneous at approximately 10 to 12 cm proximal to the tip of the lateral malleolus. It exits the lateral compartment to run anteriorly, innervating the dorsum of the foot.
Question 10364
Topic: 2. Trauma
A patient sustains a vertically unstable pelvic fracture involving the sacral ala. Postoperatively, the patient demonstrates an inability to plantarflex the great toe and loss of sensation over the lateral plantar aspect of the foot. Which nerve root was most likely injured?
Correct Answer & Explanation
. L4
Explanation
The S1 nerve root provides motor innervation for plantar flexion and sensation to the lateral and plantar aspect of the foot. Sacral ala fractures traversing the sacral foramina commonly place the L5 or S1 nerve roots at risk.
Question 10365
Topic: 2. Trauma
A runner develops acute exertional compartment syndrome requiring fasciotomies. Which of the following muscles is located exclusively within the deep posterior compartment of the leg?
Correct Answer & Explanation
. Gastrocnemius
Explanation
The deep posterior compartment of the leg contains the tibialis posterior, flexor hallucis longus, and flexor digitorum longus muscles. It also houses the posterior tibial artery and the tibial nerve.
Question 10366
Topic: 2. Trauma
An extensile lateral approach is planned for an intra-articular calcaneus fracture. The sural nerve is at risk in the posterolateral corner of the flap. From which two nerves does the sural nerve primarily derive its origins?
Correct Answer & Explanation
. Saphenous and superficial peroneal nerves
Explanation
The sural nerve is formed by the confluence of the medial sural cutaneous nerve (a branch of the tibial nerve) and the sural communicating branch (from the lateral sural cutaneous nerve, a branch of the common peroneal nerve).
Question 10367
Topic: 2. Trauma
A patient sustains a spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture) and presents with wrist drop. The radial nerve is at high risk as it pierces which muscle septum to transition from the posterior to the anterior compartment of the arm?
Correct Answer & Explanation
. Medial intermuscular septum
Explanation
The radial nerve runs in the spiral groove of the humerus and pierces the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle. It transitions from the posterior compartment to the anterior compartment at this level.
Question 10368
Topic: Lower Extremity Trauma
An anterolateral approach to the proximal tibia is performed for a Schatzker type III tibial plateau fracture. Dissection is carried out between the tibialis anterior and extensor digitorum longus. Which neurovascular bundle supplies this compartment and courses on the anterior surface of the interosseous membrane?
Correct Answer & Explanation
. Deep peroneal nerve and anterior tibial artery
Explanation
The anterior compartment of the leg is supplied by the deep peroneal nerve and the anterior tibial artery. These structures run together distally on the anterior surface of the interosseous membrane.
Question 10369
Topic: Pelvic & Acetabular Trauma
During single-leg stance, the hip abductor muscles must generate sufficient force to maintain a level pelvis. In a normal adult hip, the ratio of the body weight moment arm to the abductor moment arm is approximately 2.5 to 1. If a patient weighs 800 N, what is the approximate joint reaction force across the hip during single-leg stance?
Correct Answer & Explanation
. 2800 N
Explanation
To maintain a level pelvis in single-leg stance, the torque generated by the abductors must equal the torque of the body weight. Given the moment arm ratio is 2.5:1, Abductor Force × 1 = Body Weight × 2.5. Therefore, Abductor Force = 800 N × 2.5 = 2000 N. The total joint reaction force (JRF) across the hip is the sum of the body weight and the abductor force pulling the femur into the acetabulum. JRF = 800 N + 2000 N = 2800 N (which is 3.5 times body weight).
Question 10370
Topic: 2. Trauma
A 75-year-old female sustains a distal femur fracture just superior to a well-fixed posterior-stabilized total knee arthroplasty component.
The fracture is displaced but the joint line is maintained. What is the most appropriate surgical management?
Correct Answer & Explanation
. Distal femoral replacement
Explanation
This is a Lewis-Rorabeck Type II periprosthetic fracture (displaced fracture, well-fixed components). The standard of care is open reduction internal fixation (ORIF) with a lateral locking plate or a retrograde intramedullary nail.
Question 10371
Topic: 2. Trauma
A healthy, active 72-year-old man tripped and fell, landing on his left hip 10 weeks after an uncomplicated left primary uncemented total hip replacement. He was unable to bear weight and was brought to the emergency department. Examination revealed a slightly shortened left lower extremity and some mild ecchymosis just distal to the left greater trochanteric region, but his skin was intact without abrasions or lacerations. What is the most appropriate treatment?
Correct Answer & Explanation
. Open reduction and revision of the femoral implant to a long fluted and tapered uncemented stem
Explanation
This patient has a periprosthetic femoral fracture with a loose femoral stem and normal femoral bone stock (Vancouver type B2). The most appropriate treatment is fixation of the fracture along with revision of the stem. Considering his age, bone quality, and activity level, a longer uncemented stem is most predictable. Although a cylindrical stem may also be used, the fluted stem option is the only uncemented choice listed and the most appropriate response. A cemented stem is a poorer choice because it is difficult to keep the cement out of the fracture site; this would pose risk for nonunion at the fracture, and overall poorer results have been associated with long cemented stems in healthy, active people. Surgery does not need to be delayed to allow the ecchymosis to resolve, and simple open reduction and fixation does not address the loose stem.
Question 10372
Topic: 2. Trauma
What limits indications for the use of constrained liners?
Correct Answer & Explanation
. High failure rates associated with their use
Explanation
Because of reports of relatively high failure rates associated with constrained liners, indications are limited to continued instability after appropriate component position or deficient abductor mechanism and instability. Neither cost nor technical insertion issues are relevant with regard to indications for use. Periprosthetic fractures are not associated with constrained liner usage.
Question 10373
Topic: Pelvic & Acetabular Trauma
In patients with Crowe types III and IV developmental dysplasia of the hip with high hip centers, acetabular reconstruction often requires lowering the acetabular component into the native acetabulum. In doing so, significant risk for limb lengthening beyond 4 cm exists, making the hip difficult to reduce and also raising risk for nerve injury. Which technique is used to overcome this problem?
Correct Answer & Explanation
. Subtrochanteric osteotomy with femoral shortening
Explanation
When significant lengthening of a dysplastic hip will occur because a high dislocation is relocated into a significantly lower acetabulum, a femoral shortening may be necessary to reduce the hip and avoid a stretch injury to the sciatic nerve. No other choice specifically addresses the need for femoral shortening, and high offset stems and lateralized liners may exacerbate the problem if used alone and without femoral shortening.
Question 10374
Topic: 2. Trauma
Figures 85a and 85b are the radiographs of an 81-year-old woman who is brought to the emergency department after tripping and landing on her right knee. She had a right total knee replacement 8 years before this injury. The replacement had functioned well, but now she cannot bear weight and examination shows swelling and an abrasion over the patella. Neurovascular examination is unremarkable. What is the most appropriate treatment?
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Correct Answer & Explanation
. Urgent open reduction and internal fixation using cerclage cables
Explanation
This patient has a periprosthetic distal femoral fracture above a well-fixed femoral implant. This is a long spiral fracture and revision of her implant is not required. The level of the fracture is suitable for fixation. The most reliable fixation method is use of a locking screw plate. Cerclage fixation with cables is insufficient for this fracture. Surgery does not need to be delayed for healing of the patellar abrasion because the surgical approach is distant to the abrasion.
Question 10375
Topic: Lower Extremity Trauma
This is a CT scan at the level of the distal femur and femoral component. What is the orientation of the femoral component in the CT scan?
Correct Answer & Explanation
. Internally rotated
Explanation
A CT scan with metal artifact reduction is a useful study to evaluate femoral component rotation. Proper rotation would show that the transepicondylar line and posterior condylar line are parallel. The femoral component is internally rotated compared to the femoral epicondylar axis.
Question 10376
Topic: 2. Trauma
A 24-year-old male is brought to the trauma bay following a high-speed motorcycle collision. He has bilateral closed femoral shaft fractures and a severe closed head injury. His initial vitals are: HR 130, BP 85/50 mmHg. Arterial blood gas reveals pH 7.15, base excess -10, and lactate 6.0 mmol/L. Resuscitation is initiated. According to the principles of Damage Control Orthopedics (DCO), what is the most appropriate initial management of his bilateral femur fractures?
Correct Answer & Explanation
. Bilateral reamed cephalomedullary nailing
Explanation
This patient is in extremis and acidotic (pH 7.15, lactate 6.0, base excess -10) with hemodynamic instability. According to damage control orthopedics (DCO) principles, patients who are unstable, in extremis, or borderline with worsening parameters should undergo rapid, minimally invasive stabilization of major long bone fractures (such as external fixation) to minimize the 'second hit' of surgery. Early Total Care (ETC) with reamed intramedullary nailing is indicated in hemodynamically stable patients without severe physiological derangement.
Question 10377
Topic: Pelvic & Acetabular Trauma
A 38-year-old female pedestrian is struck by a vehicle. She arrives hypotensive (BP 75/40 mmHg) with a mechanically unstable pelvis. An anterior-posterior compression (APC) type III injury is suspected. A pelvic binder is to be applied. What is the optimal anatomic landmark to center the pelvic binder to maximize reduction of the pelvic volume?
Correct Answer & Explanation
. The greater trochanters
Explanation
For emergency stabilization of a mechanically unstable, open-book type pelvic ring injury (APC II/III), a pelvic binder or sheet should be centered over the greater trochanters. Placing the binder over the greater trochanters effectively provides an inward force vector that closes the anterior pelvic ring and reduces pelvic volume, aiding in hemorrhage control. Placement over the iliac crests is less effective and may paradoxically widen the true pelvis.
Question 10378
Topic: 2. Trauma
A 42-year-old male falls from a height of 20 feet. Pelvic radiographs and CT scan are obtained. Which of the following radiographic findings is pathognomonic for an associated both-column acetabular fracture?
Correct Answer & Explanation
. A fracture line traversing the obturator ring
Explanation
The 'spur sign' is a pathognomonic radiographic feature of an associated both-column acetabular fracture. It is best appreciated on the obturator oblique radiograph and represents the intact posterior portion of the ilium (strut of bone connected to the axial skeleton) from which the articular fragments of the acetabulum have separated. In a true both-column fracture, no portion of the articular surface remains attached to the intact axial skeleton.
Question 10379
Topic: 2. Trauma
A 28-year-old male sustains a closed, isolated Pauwels type III (vertical shear) femoral neck fracture. Which of the following fixation constructs is most biomechanically advantageous for mitigating the high shear forces across this fracture pattern?
Correct Answer & Explanation
. A fixed-angle sliding hip screw (DHS) with an anti-rotation screw
Explanation
Pauwels type III femoral neck fractures in young adults have a highly vertical fracture line (>50 degrees), which subjects the fracture to tremendous shear forces. Biomechanical studies demonstrate that a fixed-angle device, such as a sliding hip screw (with a derotational screw to prevent rotation of the head during lag screw insertion and physiological loading), offers superior biomechanical stability compared to multiple parallel cannulated screws, which have a high failure rate in this specific fracture pattern.
Question 10380
Topic: 2. Trauma
A 35-year-old female presents with a highly comminuted intra-articular distal femur fracture (OTA/AO 33-C3) after a motor vehicle collision. A coronal plane fracture of the lateral femoral condyle (Hoffa fragment) is identified on CT scan. What is the optimal surgical approach and initial fixation strategy for this specific fragment?
Correct Answer & Explanation
. Posterior approach with posterior-to-anterior non-lagged cortical screws
Explanation
A Hoffa fracture is a coronal plane fracture of the femoral condyle, most commonly involving the lateral condyle. Optimal fixation typically involves an anterior-to-posterior (AP) approach for screw placement, using partially threaded lag screws (or fully threaded screws placed in lag fashion) to achieve absolute stability and interfragmentary compression. This is critical for articular restoration and healing. Countersinking the screw heads is required if placed through the articular cartilage.
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