ABOS Hip MCQs (Set 3): Femoral Neck Fracture Questions

Question 1

During total knee arthroplasty, what component position aids in proper tracking and stability of the patellar component?

Explanation

The femoral component should be implanted with enough external rotation to facilitate patellar tracking. Proper tracking requires a normal Q angle and is affected by axial and rotational alignment of the femur and tibia. An excessive Q angle can result from internal rotation of either component, medialization of the tibial tray, or lateralization of the patellar component. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 559-582.

Question 2

An otherwise healthy 57-year-old woman has limited range of motion and moderate effusion after undergoing total knee arthroplasty 6 months ago. One of two cultures of joint aspirate reveals methicillin-resistant Staphylococcus epidermidis. Management should now consist of

Explanation

The rapidly increasing prevalence of infection from Staphylococcus epidermidis has made this the most frequently cultured organism. In most patients, the infection occurred intraoperatively, thereby resulting in a chronic infection if not detected within the first 6 weeks after surgery. Irrigation of the joint may be successful during this time in 60% of patients, but the most successful treatment is extirpation for 6 weeks, followed by delayed reimplantation. This approach may result in a salvage rate of as high as 90% in some patients. Drancourt M, Stein A, Argenson JN, et al: Oral rifampin plus ofloxacin for treatment of staphylococcus-infected orthopedic implants. Antimicrob Agents Chemother 1993;37:1214-1218. Duncan CP, Beauchamp C: A temporary antibiotic-loaded joint replacement system for the management of complex infections involving the hip. Orthop Clin North Am 1993;24:751-759.

Question 3

Figure 13 shows the radiographs of a 56-year-old woman who has pain and varus knee deformity after undergoing total knee arthroplasty 8 years ago. Aspiration and studies for infection are negative. During revision surgery, management of the tibial bone loss is best achieved by

Explanation

Massive bone loss encountered in revision total knee arthroplasty remains a significant challenge. Recent reports have shown high success rates using structural allograft to reconstruct massive bone defects. Custom and hinged prostheses in this setting are no longer favored. The defect shown is segmental and is too large to be filled with cement or iliac crest bone graft. Mow CS, Wiedel JD: Structural allografting in revision total knee arthroplasty. J Arthroplasty 1996;11:235-241. Engh GA, Herzwurm PJ, Parks NL: Treatment of major defects of bone with bulk allografts and stemmed components during total knee arthroplasty. J Bone Joint Surg Am 1997;79:1030-1039.

Question 4

Varus intertrochanteric osteotomy for coxa valga commonly produces which of the following results?

Explanation

The greater trochanter is raised as a by-product of varus osteotomy, and a temporary abductor lag and lurch is common for 6 months following surgery. In the absence of hip joint subluxation, varus intertrochanteric osteotomy has no effect on the center edge angle of Wiberg. Varus osteotomy typically increases femoral offset, thereby improving the abductor lever arm and reducing the hip joint reaction force. Even without taking a wedge, varus osteotomy always produces some degree of shortening.

Question 5

A 65-year-old woman has nausea, vomiting, and abdominal distention after undergoing total knee arthroplasty 48 hours ago. An abdominal radiograph is shown in Figure 14. Associated risk factors for this disorder include

Explanation

The prevalence of postoperative ileus associated with total joint arthroplasty has been reported to be as high as 3%. Metabolic abnormalities such as hypokalemia are believed to contribute to the onset of ileus and Ogilvie's syndrome (acute pseudo-obstruction of the colon). Prolonged bed rest also has been associated with the development of ileus and Ogilvie's syndrome. Untreated Ogilvie's syndrome can result in cecal perforation. Ileus usually is not accompanied by mechanical obstruction. Antibiotic administration and the type of anesthesia used have not been correlated with development of ileus. Administration of warfarin has been associated with elevated prothrombin time/partial thromboplastin time and international normalized ratio levels when ileus is managed with a nasogastric tube and suction. Metabolic imbalances must be corrected to reverse the ileus process. Iorio R, Healy WL, Appleby D: The association of excessive warfarin anticoagulation and postoperative ileus after total joint replacement surgery. J Arthroplasty 2000;15:220-223.

Question 6

A 77-year-old woman with osteoporosis who underwent cemented total hip arthroplasty 12 years ago fell down a flight of stairs. A radiograph is shown in Figure 15. What is the best option for treating this fracture?

Explanation

Type I fractures are trochanteric fractures usually secondary to osteolysis. Type II fractures are located around the stem. Type III fractures are distal to the stem. If the fracture and prosthesis are stable, the fracture can be treated nonsurgically. If the fracture is unstable, the stability of the prosthesis should be assessed. If the prosthesis is unstable (type IIB), treatment should consist of revision to a long stem prosthesis that bypasses the fracture by two cortical diameters. If, as in this patient, the prosthesis is not loose (type IIA), open reduction and internal fixation is the appropriate option. Proximal femoral allograft is appropriate for type IIIC fractures in which the proximal bone is significantly compromised and the femoral component is loose. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 455-492.

Question 7

Total hip arthroplasty in a patient with a long-standing hip fusion on the contralateral side is most likely to result in

Explanation

Contralateral total hip arthroplasty in patients with hip fusions results in a 40% higher rate of mechanical failure and loosening. During gait, motion of the contralateral hip is increased and more time is spent bearing weight on that hip. In patients with hip fusions, gait efficiency is only 53%, with a greater rate of oxygen consumption. Garvin KL, Pellicci PM, Windsor RE, et al: Contralateral total hip arthroplasty or ipsilateral total hip arthroplasty in patients who have long-standing fusion of the hip. J Bone Joint Surg Am 1989;71:1355-1362. Gore DR, Murray MP, et al: Walking patterns of men with unilateral surgical hip fusion. J Bone Joint Surg Am 1975;57:759-765.

Question 8

A 60-year-old woman reports anterior knee pain 2 years after undergoing primary total knee arthroplasty for rheumatoid arthritis. A Merchant view of the patella is shown in Figure 16. What is the most likely cause of her pain?

Explanation

Patellar complications commonly occur after primary total knee arthroplasty; therefore, proper component positioning is critical in obtaining a successful result. This patient has lateral tilting and subluxation of the patellar component. Internal rotation of the femoral component has the most deleterious effect on patellar tracking. Lateral placement of the femoral component, medial placement of the patellar component, and external rotation of the tibial component have beneficial effects on patellar tracking. Elevation of the joint line, if not excessive, should not impact patellar tracking. Rand JA: Patellar resurfacing in total knee arthroplasty. Clin Orthop 1990;260:110-117.

Question 9

The anterior portal of a hip arthroscopy places what structure at greatest risk for injury?

Explanation

The average location of the anterior portal is 6.3 cm distal to the anterior superior iliac spine. The lateral femoral cutaneous nerve typically has divided into three or more branches at the level of the anterior portal. The portal usually passes within several millimeters of the most medial branch. Injury to the nerve can lead to meralgia paresthetica. The femoral nerve lies an average minimum distance of 3.2 cm from the anterior portal. The ascending branch of the lateral circumflex artery lies approximately 3.7 cm inferior to the anterior portal. Neither the ascending branch of the medial circumflex artery nor the superior gluteal nerve are at risk. Byrd JWT: Operative Hip Arthroscopy. New York, NY, Thieme Medical Publishers, 1998, pp 83-91.

Question 10

Figure 17 shows the radiograph of an 80-year-old woman who has left groin pain. She underwent a total hip arthroplasty 15 years ago and has no history of hip dislocation; however, she now reports that the pain results in functional impairment. Preoperative findings reveal that the component used has been discontinued, the locking mechanism is poor, and there is no replacement polyethylene available from the company. During surgery, the acetabular component is found to be well fixed, it is in satisfactory position, and adequate access can be obtained through the screw holes in the component to debride the osteolytic cavities. What is the best course of action for revision?

Explanation

The clinical result in this patient has been good, with no dislocations, suggesting that the components are in reasonably good position. The radiograph and examination at the time of surgery suggest that the acetabular component is well fixed. The surrounding bone of the acetabulum is osteopenic and there would most likely be considerable bone loss if the acetabular component is removed. Access to the osteolytic lesions is possible. Cementing an acetabular component into the retained socket will cause the least amount of bone loss, shorten the procedure, and most likely result in a functional hip. Maloney WJ: Socket retention: Staying in place. Orthopedics 2000;23:965-966.

Question 11

The need for postoperative allogeneic blood transfusions after total hip arthroplasty has been shown to be reduced when using

Explanation

In a prospective study, 216 patients were randomized into three groups consisting of low-dose preoperative erythropoietin, high-dose preoperative erythropoietin, and placebo control. All patients were treated for 4 weeks prior to total hip arthroplasty. Both the low- and high-dose erythropoietin groups had a significantly lower rate of blood transfusions (p < 0.001) after surgery. Waddell JP: Evidence-based orthopedics. J Bone Joint Surg Am 2001;83:788.

Question 12

Which of the following is considered a major characteristic of hyaluronate?

Explanation

Hyaluronate is a naturally occurring compound that is the backbone of the central core of the proteoglycan aggregate. Cartilage is made of two principal tissue structures. The connective tissue component includes collagen, which forms the framework for structural strength and elasticity. The proteoglycan aggregate provides a unique property of water incorporation and friction reduction capabilities. Hyaluronate forms the base or central core of the aggregate on which a link protein binds a protein core. Chondroitin sulfate and keratin sulfate are then bound to this protein core, forming the terminal extension of the aggregate. Callaghan JJ, Dennis DA, Paprosky WA, Rosenberg AG (eds): Orthopedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 69-78. Felson DT: Osteoarthritis. Rheum Dis Clin North Am 1990;16:499-512.

Question 13

Which of the following is considered an important factor in improved cemented femoral stem survivorship?

Explanation

Cement technique, relative stem to canal size and position, stem design, surgical technique, and femoral anatomy are important factors in cemented stem survivorship. Varus stem position, a wide diaphyseal to metaphyseal ratio (stovepipe femur), thin cement mantles (1 mm or less), and nonrounded femoral stem designs are negative prognostic factors for stem survivorship. Precoating with methylmethacrylate has not been shown to provide any increased survivorship over nonprecoated stems. Noble PC, Collier MB, Maltry JA, Kamaric E, Tullos HS: Pressurization and centalization enhance the quality and reproducibility of cement mantles. Clin Orthop 1998;355:77-89. Crowninshield RD, Brand RA, Johnston RC, Milroy JC: The effect of femoral stem cross-sectional geometry on cement stresses in total hip reconstruction. Clin Orthop 1980;146:71-77.

Question 14

An acetabular reinforcement cage is most often indicated for which of the following conditions?

Explanation

An acetabular reinforcement cage is required infrequently except when there is pelvic discontinuity in which there is no posterior column support of the acetabular cup. A larger cup inserted with cement and morselized bone graft is an effective technique for contained cavitary and anterior wall defects. Zone 1 osteolysis and a medial wall defect are essentially the same as a contained cavitary defect and can be reconstructed using cementless cups. Berry DJ, Lewallen DG, Hanssen A, Cabanela ME: Pelvic discontinuity in revision total hip arthroplasty. J Bone Joint Surg Am 1999;81:1692-1702.

Question 15

What is the most common short-term complication following femoral impaction grafting for revision total hip arthroplasty?

Explanation

Impaction grafting is an alternative for severe femoral bone deficiency; however, stem subsidence is commonly observed during the first few months. Slight subsidence is felt to be integral to the success of the procedure. Predictable bone graft incorporation and stable stem fixation have been reported in the medium-term. The incidence of periprosthetic fractures has been reported as high as 24%. Mikhail MWE, Weidenhielm L, Jazrawi LM, et al: Collarless, polished, tapered stem failure. J Bone Joint Surg Am 2000;82:1513-1514.

Question 16

Which of the following is considered the most predictive factor in determining whether a patient will need a blood transfusion after total knee arthroplasty?

Explanation

Multiple studies have shown that the preoperative hemoglobin level is the most predictive factor in determining whether a transfusion will be necessary after total hip or total knee arthroplasty. Studies have not shown any correlation with the other options. Salido JA, Marin LA, Gomez LA, Zorrilla P, Martinez C: Preoperative hemoglobin levels and the need for transfusion after prosthetic hip and knee surgery: Analysis of predictive factors. J Bone Joint Surg Am 2002;84:216-220. Sculco TP, Gallina J: Blood management experience: Relationship between autologous blood donation and transfusion in orthopedic surgery. Orthopedics 1999;22:S129-S134.

Question 17

A 32-year-old man has posttraumatic arthritis after undergoing open reduction and internal fixation of a left acetabular fracture. A total hip arthroplasty is performed, and the radiograph is shown in Figure 18. What is the most common mode of failure leading to revision in this group of patients?

Explanation

Acetabular component loosening has been reported as the most common mode of failure following total hip arthroplasty in patients with a previous acetabular fracture. Following acetabular fracture and subsequent open reduction and internal fixation, the bone quality and vascularity are compromised, thus reducing the success rate of acetabular component cementless fixation. Jimenez ML, Tile M, Schenk RS: Total hip replacement after acetabular fracture. Orthop Clin 1997;28:435-446.

Question 18

A 42-year-old man sustained the periprosthetic fracture shown in Figures 19a and 19b. The femoral component is well fixed. What is the next most appropriate step in management?

Explanation

The patient has a periprosthetic fracture below the femoral stem. The component is porous coated and well fixed. Open reduction and internal fixation, leaving the stem in place, can be performed when bone quality is good. Plating with or without allograft struts and supplemental cerclage fixation generally is acceptable. If the component is loose, revision to a longer device is recommended with appropriate stabilization of the fracture using the aforementioned methods. If bone loss has occurred, allograft supplementation or a tumor prosthesis may be indicated. Fractures located well below the stem tip can be treated without regard for the prosthesis. Closed reduction and bracing is not associated with good results for periprosthetic femoral fractures. Retrograde intramedullary nailing is not appropriate for this fracture. Duncan CP, Masri BA: Fractures of the femur after hip replacement. Instr Course Lect 1995;44:293-304.

Question 19

A 58-year-old man has anterior knee pain after undergoing total knee arthroplasty for osteoarthritis 2 years ago. He denies any history of trauma. A Merchant view is shown in Figure 20. What is the most likely cause of his pain?

Explanation

The patient has a patellar stress fracture after resurfacing in a total knee arthroplasty. Several studies have shown that over-resection of the patella to less than 12 to 15 mm increases anterior patellar surface strains to a point where the risk of fracture is increased. Increasing the patellar thickness, positioning of the femoral component, lateral releases, and component types have not been clearly associated with increased fracture risk. Reuben JD, McDonald CL, Woodard PL, Hennington LJ: Effect of patella thickness on patella strain following total knee arthroplasty. J Arthroplasty 1991;6:251-258. Hsu HC, Luo ZP, Rand JA, An KN: Influence of patellar thickness on patellar tracking and patellofemoral contact characteristics after total knee arthroplasty. J Arthroplasty 1996;11:69-80.

Question 20

A 30-year-old patient has acetabular dysplasia and moderate secondary osteoarthrosis. Which of the following studies will best help predict the success of periacetabular osteotomy?

Explanation

Improvement in the appearance of the hip joint on functional radiographic evaluation (abduction/adduction views) has been shown to be predictive of outcome following joint preserving surgery. CT and MRI findings have not been shown to be predictive of outcome.

Question 21

Which of the following is considered a specific advantage of using COX-2 inhibitors over COX-1 inhibitors?

Explanation

Inflammation is mediated through two isoforms of cyclooxygenase that convert arachidonic acid to prostaglandins. Selectivity, but not specificity, is one of the unique characteristics of this process that has been able to provide more protection from the effects of gastric mucosal alterations using the COX-2 selective inhibitors. The use of COX-1 selective inhibitors is associated with side effects such as ulcerative conditions and platelet interference, both of which have been difficult to control in the past until the advent of the COX-2 inhibitors. PGE2 inhibition by COX-1 in the intestinal track can then be bypassed, thereby reducing ulceration complications associated with use of nonsteroidal anti-inflammatory drugs. Lane JM: Anti-inflammatory medications: Selective COX-2 inhibitors. J Am Acad Orthop Surg 2002;10:75-78. Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002.

Question 22

Which of the following is not a reported mode of failure for a constrained acetabular component?

Explanation

There is no evidence of increased polyethylene wear in constrained acetabular components. The rates of wear appear to be the same using standard or constrained liners. Lachiewicz PF, Kelley SS: Constrained components in total hip arthroplasty. J Am Acad Orthop Surg 2002;10:233-238. Anderson MJ, Murray WR, Skinner HB: Constrained acetabular components. J Arthroplasty 1994;9:17-23.

Question 23

Which of the following factors is most likely to be associated with prolonged survival of total knee arthroplasty?

Explanation

In a survivorship study of 9,200 total knee arthroplasties, Rand and Ilstrup identified four independent variables associated with a significantly lower risk of failure: primary total knee arthroplasty, diagnosis of rheumatoid arthritis, age of 60 years or older, and use of a condylar prosthesis with a metal-backed tibial component. Other clinical studies report the use of a posterior stabilized prosthesis to be comparable to a total condylar prosthesis with retained posterior cruciate ligament. Rand JA, Ilstrup DM: Survivorship analysis of total knee arthroplasty: Cumulative rates of survival of 9200 total knee arthroplasties. J Bone Joint Surg Am 1991;73:397-409. Stern SH, Insall JN: Posterior stabilized prosthesis: Results after follow-up of nine to twelve years. J Bone Joint Surg Am 1992;74:980-986.

Question 24

Analysis of primary total hip arthroplasty using press-fit acetabular components without supplementary screw fixation reveals that screw fixation

Explanation

Using mechanical failure of fixation as the end point, Udomkiat and associates demonstrated a 12-year survivorship of 99.1% for titanium press-fit acetabular components without supplementary screw fixation. This study suggests that it is unlikely that the use of supplementary screws would lead to improved results. In addition, polyethylene wear debris tends to migrate through screw holes and along the course of screws. Screw holes also decrease the available surface for bone ingrowth. Screws that back up may be a source of backside polyethylene wear. This suggests that screw holes and the use of screws should be avoided when they are unnecessary for cup fixation.

Question 25

Dislocation following primary total hip arthroplasty is more likely to occur in which of the following situations?

Explanation

Dislocation following total hip arthroplasty is twice as common in women than in men. It is more likely to occur in older patients. There is no clear association between dislocation and the method of fixation or the type of bearing, so long as the bearing diameter is the same.

Question 26

A 35-year-old healthy male sustains a vertically oriented, displaced femoral neck fracture (Pauwels III). Which of the following fixation constructs provides the most biomechanically stable fixation for this specific fracture pattern?

Explanation

Pauwels III femoral neck fractures have a vertical orientation, subjecting the fracture to high shear forces. A fixed-angle construct, such as a sliding hip screw combined with an anti-rotation screw, provides superior biomechanical stability compared to multiple cannulated screws.

Question 27

A highly active 68-year-old male presents with a displaced femoral neck fracture. He is medically optimized and a decision is made between total hip arthroplasty (THA) and hemiarthroplasty. According to current literature, which of the following is true regarding THA compared to hemiarthroplasty in this patient population?

Explanation

In active, healthy older patients, THA for displaced femoral neck fractures provides better functional outcomes and lower revision rates than hemiarthroplasty. However, it is consistently associated with a higher risk of postoperative dislocation.

Question 28

A 78-year-old female presents with thigh pain and inability to bear weight after a mechanical fall. Radiographs demonstrate a transverse periprosthetic femur fracture around a fully porous-coated femoral stem placed 10 years ago. The stem appears loose on radiographs, but there is adequate proximal bone stock.

What is the most appropriate treatment?

Explanation

This is a Vancouver B2 periprosthetic fracture (loose stem, good bone stock). The standard of care is revision arthroplasty using a long uncemented diaphyseal-engaging stem to bypass the fracture, often supplemented with cables.

Question 29

A 55-year-old male with a ceramic-on-ceramic total hip arthroplasty complains of a loud, high-pitched squeaking noise with ambulation. Which of the following factors is most strongly associated with this complication?

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading. This most commonly results from component malposition, specifically increased acetabular cup inclination (a steep cup) or extremes of version.

Question 30

During the cementation and pressurization phase of a cemented hemiarthroplasty for a femoral neck fracture, the patient's blood pressure drops acutely to 70/40 mmHg, accompanied by severe hypoxia. What is the primary pathophysiologic mechanism of this event?

Explanation

Bone cement implantation syndrome (BCIS) presents with hypoxia, hypotension, and arrhythmias during cementation. It is primarily caused by the embolization of marrow, fat, and air into the pulmonary venous circulation during medullary pressurization.

Question 31

A 45-year-old female presents with unexplained groin pain 5 years after receiving a metal-on-metal total hip arthroplasty. Her radiographs are unremarkable. What is the most appropriate initial diagnostic workup for the suspected pathology?

Explanation

Patients with metal-on-metal implants and unexplained pain should be evaluated for adverse local tissue reaction (ALTR) or pseudotumors. The initial workup involves checking serum cobalt and chromium ion levels and obtaining a metal artifact reduction sequence (MARS) MRI.

Question 32

Following a primary total hip arthroplasty, a patient is noted to have a new-onset sciatic nerve palsy. Which of the following motor deficits is most likely to be present on physical examination?

Explanation

The peroneal division of the sciatic nerve is most commonly injured during THA due to its lateral position and relative tethering at the fibular head. This injury classically results in foot drop (weakness in ankle dorsiflexion and extensor hallucis longus).

Question 33

A 24-year-old male sustains a nondisplaced femoral neck fracture following a fall from height. He is treated with percutaneous cannulated screw fixation. Which of the following factors is most critical in minimizing his risk of developing avascular necrosis (AVN) of the femoral head?

Explanation

In young adults with femoral neck fractures, anatomic reduction and rigid fixation are the most critical factors in minimizing the risk of nonunion and avascular necrosis. The routine use of capsulotomy to decompress intracapsular hematoma remains controversial.

Question 34

A 60-year-old female complains of anterior groin pain 1 year after an uncomplicated total hip arthroplasty. The pain is worst when she actively raises her leg to get into a car. Radiographs reveal the acetabular component has 10 degrees of anteversion and a prominent anterior rim. Conservative management has failed. What is the most appropriate surgical treatment?

Explanation

Iliopsoas impingement classically presents as groin pain with active hip flexion (e.g., getting into a car) and is often caused by a prominent anterior acetabular rim. If prolonged conservative measures fail, an iliopsoas tenotomy is highly successful and less morbid than cup revision.

Question 35

A 42-year-old male presents with progressively worsening hip pain. Radiographs demonstrate a crescent sign and early subchondral collapse of the femoral head, but the joint space is preserved (Ficat Stage III).

What is the most reliable definitive treatment for this patient?

Explanation

Ficat Stage III avascular necrosis involves subchondral collapse without significant acetabular involvement. Once mechanical collapse has occurred, head-preserving procedures have high failure rates, making total hip arthroplasty the most reliable option for pain relief and function.

Question 36

During a standard posterior approach to the hip for arthroplasty, preserving the insertion of the quadratus femoris muscle or remaining proximal to it is recommended to protect which of the following vascular structures?

Explanation

The ascending branch of the medial circumflex femoral artery (MCFA) runs near the inferior border of the obturator externus and the superior border of the quadratus femoris. Protecting the quadratus femoris during a posterior approach helps prevent injury to the MCFA.

Question 37

A surgeon utilizes a direct lateral (Hardinge) approach for a total hip arthroplasty. The gluteus medius is split longitudinally. Extending this split more than 5 cm proximal to the tip of the greater trochanter places which nerve at significant risk?

Explanation

The superior gluteal nerve innervates the gluteus medius, minimus, and tensor fasciae latae. It enters the deep surface of the gluteus medius approximately 3 to 5 cm proximal to the greater trochanter; splitting the muscle proximal to this point risks denervation and a severe Trendelenburg gait.

Question 38

An 88-year-old female nursing home resident with severe dementia and minimal ambulatory capacity sustains a displaced femoral neck fracture. Which of the following is the most appropriate surgical intervention?

Explanation

For low-demand, elderly patients with displaced femoral neck fractures, a cemented unipolar hemiarthroplasty provides immediate stability for weight-bearing and reliable pain relief. Cementing the stem significantly reduces the risk of postoperative periprosthetic fractures compared to uncemented designs.

Question 39

When evaluating a patient for a potential metal-on-metal total hip arthroplasty, which of the following medical conditions is widely considered an absolute contraindication to this bearing surface?

Explanation

Metal ions (cobalt and chromium) generated by metal-on-metal articulations are renally excreted. Severe renal failure is an absolute contraindication due to the inability to clear these ions, leading to systemic accumulation and toxicity.

Question 40

A 35-year-old man sustains a completely displaced, vertically oriented femoral neck fracture (Pauwels type III) after a fall from a height.

Which of the following internal fixation constructs provides the greatest biomechanical stability for this fracture pattern?

Explanation

Pauwels type III fractures are highly vertical and subject to significant shear forces. Biomechanical studies demonstrate that a sliding hip screw combined with an anti-rotation screw provides superior stability against shear and varus displacement compared to multiple cannulated screws.

Question 41

When comparing total hip arthroplasty (THA) to hemiarthroplasty for the treatment of a displaced femoral neck fracture in an active, independent 72-year-old woman, which of the following statements is most accurate?

Explanation

In functionally active elderly patients, THA yields better functional outcomes and lower reoperation rates (mainly due to avoidance of acetabular wear). However, THA carries a historically higher risk of postoperative dislocation compared to hemiarthroplasty.

Question 42

A 78-year-old man with a displaced femoral neck fracture undergoes a primary total hip arthroplasty. Compared to a patient undergoing total hip arthroplasty for elective primary osteoarthritis, this patient is at an increased risk for which of the following complications?

Explanation

THA performed for acute femoral neck fractures has a significantly higher rate of postoperative dislocation (up to 5-10%) compared to THA performed for elective primary osteoarthritis (approx. 1%). Soft tissue laxity and lack of capsular contracture contribute to this risk.

Question 43

During closed reduction and internal fixation of a displaced femoral neck fracture, care must be taken to minimize further injury to the primary blood supply of the adult femoral head. Which of the following vessels provides the majority of this blood supply?

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) provides the primary blood supply to the adult femoral head via the lateral epiphyseal (retinacular) vessels. The lateral femoral circumflex and artery of the ligamentum teres provide minimal contribution in adults.

Question 44

A meta-analysis comparing unipolar and bipolar hemiarthroplasty for the treatment of displaced femoral neck fractures in the elderly would most likely demonstrate which of the following findings?

Explanation

Multiple randomized trials and meta-analyses have shown no clinically significant differences in functional outcomes, dislocation rates, or symptomatic acetabular erosion between unipolar and bipolar hemiarthroplasties at intermediate follow-up, though bipolar implants are more expensive.

Question 45

A 25-year-old female marathon runner presents with insidious onset groin pain. Radiographs are normal, but an MRI reveals a focal fracture line involving the superior (tension) aspect of the femoral neck without displacement. What is the most appropriate management?

Explanation

Tension-sided femoral neck stress fractures have a high propensity for completion and displacement. They are managed operatively with in situ percutaneous cannulated screw fixation to prevent catastrophic displacement and subsequent avascular necrosis.

Question 46

A 75-year-old woman sustains a valgus-impacted femoral neck fracture. What is the primary rationale for recommending operative fixation with percutaneous cannulated screws over non-operative management?

Explanation

Valgus-impacted femoral neck fractures (Garden I) treated non-operatively have a high rate of secondary displacement (up to 15-40%). Surgical fixation is performed primarily to prevent displacement, which would necessitate more extensive surgery like arthroplasty.

Question 47

An 82-year-old woman is scheduled for a hemiarthroplasty for a displaced femoral neck fracture. When counseling the family on the choice between a cemented and an uncemented femoral stem, current evidence suggests that a cemented stem is associated with:

Explanation

Cemented stems in elderly patients with femoral neck fractures result in significantly fewer intraoperative and postoperative periprosthetic fractures and less thigh pain compared to uncemented stems, without a significant difference in 1-year mortality.

Question 48

In an 80-year-old patient with multiple medical comorbidities, surgical intervention for a displaced femoral neck fracture within 48 hours of admission has been shown to primarily decrease the risk of:

Explanation

Early surgery (within 24-48 hours) for hip fractures in the elderly is associated with fewer systemic complications (e.g., pneumonia, pressure ulcers, DVT) and a decreased 1-year mortality rate. It does not reliably decrease AVN or nonunion in this population.

Question 49

Which of the following is the strongest predictive factor for nonunion after closed reduction and internal fixation of a displaced femoral neck fracture in a 60-year-old patient?

Explanation

The quality of the surgical reduction and the initial degree of fracture displacement are the most critical determinants of successful healing. Poor reduction (varus malalignment) significantly increases the risk of nonunion and hardware failure.

Question 50

During the insertion of cemented hemiarthroplasty for a femoral neck fracture, the patient's blood pressure drops acutely and oxygen saturation falls. Bone cement implantation syndrome (BCIS) is suspected. The primary hemodynamic derangement in severe BCIS is characterized by:

Explanation

BCIS is triggered by the embolization of marrow fat and debris during cement pressurization, leading to acute pulmonary hypertension, hypoxia, right ventricular strain, and subsequent right heart failure with hypotension.

Question 51

An 81-year-old nursing home resident with severe Parkinson's disease sustains a displaced femoral neck fracture. Which of the following surgical options minimizes her risk of postoperative instability while addressing the fracture?

Explanation

Patients with neuromuscular disorders such as Parkinson's disease are at an exceptionally high risk for postoperative dislocation. Utilizing a larger head size via hemiarthroplasty or a dual mobility THA component significantly mitigates this risk.

Question 52

A 65-year-old woman undergoes conversion of a failed ORIF of a femoral neck fracture to a total hip arthroplasty. Compared to primary THA for osteoarthritis, this conversion procedure is associated with:

Explanation

Conversion THA following failed femoral neck fracture fixation is technically demanding and carries higher complication rates, including increased risks of dislocation, deep infection, intraoperative fracture, and increased blood loss, behaving more like a revision THA.

Question 53

A 45-year-old man with end-stage renal disease on hemodialysis presents with a displaced femoral neck fracture. If internal fixation is chosen over arthroplasty, the surgeon must be aware of an exceptionally high risk for which complication?

Explanation

Patients with chronic renal failure and renal osteodystrophy have very poor bone healing potential. Internal fixation of displaced femoral neck fractures in this population is associated with an unacceptably high rate of nonunion, hardware failure, and AVN, often making arthroplasty the preferred choice even in younger patients.

Question 54

A 68-year-old active man presents with a displaced femoral neck fracture. Radiographs reveal the fracture along with severe, pre-existing osteoarthritis of the ipsilateral hip characterized by joint space narrowing and large osteophytes. The most appropriate surgical treatment is:

Explanation

In a patient with a displaced femoral neck fracture and symptomatic, advanced pre-existing osteoarthritis of the same hip, a total hip arthroplasty (THA) is indicated to address both the fracture and the arthritic acetabulum. Hemiarthroplasty would result in persistent groin pain.

Question 55

When utilizing three cannulated screws for the fixation of a non-displaced femoral neck fracture, the optimal biomechanical configuration of the screws is:

Explanation

The optimal configuration for three cannulated screws is an inverted triangle. The inferior screw should run adjacent to and be supported by the calcar (inferior cortex of the neck) to provide maximum cortical support and resist varus displacement.

Question 56

A 55-year-old woman sustains a displaced femoral neck fracture. She has a history of severe pelvic radiation for cervical cancer 15 years ago. Which of the following is the most appropriate surgical management?

Explanation

Prior pelvic radiation causes radiation osteitis, severely impairing the biologic potential for bony ingrowth. If a THA is indicated, a cemented acetabular component is required, as uncemented cups have an extremely high failure rate in irradiated bone.

Question 57

A 30-year-old man involved in a motorcycle accident sustains a comminuted midshaft femur fracture and an ipsilateral, non-displaced femoral neck fracture. What is the most appropriate sequence and method of fixation?

Explanation

In ipsilateral femoral neck and shaft fractures, the priority is anatomic reduction and fixation of the femoral neck to prevent displacement and AVN. This is typically done first (e.g., with screws), followed by shaft fixation (e.g., retrograde nail or plate).

Question 58

A 77-year-old woman undergoes total hip arthroplasty for a displaced femoral neck fracture. Which of the following surgical approaches, if performed without meticulous soft-tissue repair, is associated with the highest risk of postoperative dislocation?

Explanation

The standard posterior approach, especially without a robust repair of the capsule and short external rotators, carries the highest historic risk of posterior dislocation, particularly in the femoral neck fracture population where soft tissues are lax.

Question 59

A healthy 35-year-old man sustains a displaced femoral neck fracture. When counseling the patient on the risk of avascular necrosis (AVN), which of the following is considered the most significant determining factor?

Explanation

The initial degree of fracture displacement is the most critical factor predicting the development of AVN in young patients with femoral neck fractures. While urgent reduction and fixation are recommended, initial displacement dictates the extent of irreversible vascular injury to the retinacular vessels.

Question 60

An active, independent 74-year-old woman sustains a displaced femoral neck fracture. Compared to treatment with a bipolar hemiarthroplasty, treatment with a total hip arthroplasty (THA) is associated with which of the following?

Explanation

In healthy, active elderly patients with displaced femoral neck fractures, THA provides better functional outcomes and lower long-term pain compared to hemiarthroplasty. However, THA is associated with a higher risk of dislocation and increased operative time.

Question 61

When performing a total hip arthroplasty via the direct anterior approach, the internervous plane utilized is between muscles innervated by which of the following nerves?

Explanation

The direct anterior approach exploits the internervous plane between the tensor fasciae latae (superior gluteal nerve) and the sartorius/rectus femoris (femoral nerve). This allows exposure of the hip joint without detaching muscle insertions.

Question 62

A 28-year-old female marathon runner complains of progressively worsening anterior groin pain. MRI reveals a stress fracture on the superior aspect of the femoral neck involving 60% of the neck width. What is the most appropriate management?

Explanation

Tension-sided (superior) femoral neck stress fractures have a high risk of completion and displacement, requiring prophylactic operative fixation. Compression-sided (inferior) fractures involving less than 50% of the neck can often be managed non-operatively.

Question 63

Which of the following fracture patterns of the proximal femur is biomechanically best treated with a sliding hip screw (SHS) rather than multiple parallel cancellous screws?

Explanation

Basicervical femoral neck fractures are considered extracapsular and lack the inherent stability of true transcervical fractures. They are subject to significant shear forces and are best treated with a sliding hip screw or cephalomedullary nail to prevent fixation failure.

Question 64

A 68-year-old man undergoes a cemented unipolar hemiarthroplasty for a displaced femoral neck fracture. During cement pressurization and stem insertion, the patient experiences sudden profound hypotension and hypoxia. What is the primary pathophysiologic mechanism of this complication?

Explanation

Bone cement implantation syndrome (BCIS) is primarily caused by the embolization of fat, marrow, and air into the pulmonary circulation during cement pressurization. It presents with hypoxia, hypotension, and potentially cardiac arrest.

Question 65

During preoperative templating for a total hip arthroplasty, the surgeon notes that increasing the femoral offset of the implant will result in which of the following biomechanical changes?

Explanation

Increasing femoral offset increases the lever arm of the abductor muscles, which decreases the force they must generate to balance the pelvis. This simultaneously decreases the resultant joint reaction force across the hip.

Question 66

A 45-year-old man presents with a painful nonunion of a femoral neck fracture 9 months after fixation with 3 cancellous screws. Radiographs show a vertical fracture line (Pauwels type III) with varus collapse, but MRI confirms a viable femoral head. What is the best surgical option?

Explanation

A valgus intertrochanteric osteotomy reorients the vertical fracture line to a more horizontal position, converting shear forces into compressive forces. This promotes healing of the nonunion while preserving the native, viable femoral head in a young patient.

Question 67

Which of the following vessels provides the predominant blood supply to the weight-bearing dome of the adult femoral head?

Explanation

The deep branch of the medial circumflex femoral artery (MFCA) provides the primary blood supply to the adult femoral head via the lateral epiphyseal artery. Injury to this vessel during trauma or surgery significantly increases the risk of avascular necrosis.

Question 68

A 35-year-old man sustains a displaced, vertically oriented (Pauwels type III) femoral neck fracture. Which of the following fixation constructs offers the greatest biomechanical stability for this specific fracture pattern?

Explanation

Pauwels type III fractures experience high shear forces due to their vertical orientation. A sliding hip screw with a derotation screw provides superior biomechanical stability compared to multiple cancellous screws for this fracture pattern.

Question 69

A healthy, active 72-year-old woman sustains a Garden IV femoral neck fracture. Compared to bipolar hemiarthroplasty, treatment with total hip arthroplasty (THA) is associated with a higher rate of which of the following?

Explanation

In active elderly patients with displaced femoral neck fractures, THA provides better functional outcomes and lower revision rates than hemiarthroplasty, but it carries a higher risk of postoperative dislocation.

Question 70

During a direct anterior approach for total hip arthroplasty, the internervous plane is developed between muscles supplied by which of the following nerves?

Explanation

The direct anterior approach (Smith-Petersen) utilizes the true internervous plane between the tensor fasciae latae (innervated by the superior gluteal nerve) and the sartorius and rectus femoris (innervated by the femoral nerve).

Question 71

A 45-year-old man undergoes total hip arthroplasty. Six months postoperatively, he presents with a squeaking sound from his hip during normal walking. He has no pain, and radiographs show well-fixed components. Which bearing surface was most likely used?

Explanation

Squeaking is a known complication specific to ceramic-on-ceramic articulations, with a reported incidence of up to 10%. It is generally benign if asymptomatic but may be associated with component malpositioning or edge loading.

Question 72

A 68-year-old woman with rheumatoid arthritis is scheduled for a total hip arthroplasty. Preoperative radiographs reveal severe protrusio acetabuli. During acetabular reconstruction, what is the most appropriate management to restore the anatomic center of rotation?

Explanation

The primary goal in treating protrusio acetabuli during THA is restoring the center of rotation laterally. This is best achieved using impacted morselized cancellous bone graft in the medial defect combined with a hemispherical cup.

Question 73

A 55-year-old man presents with painful clicking and groin pain 5 years after an uncemented total hip arthroplasty. Radiographs show a well-fixed femoral stem and a well-fixed acetabular shell. Blood work shows markedly elevated serum cobalt and mildly elevated chromium. What is the most likely diagnosis?

Explanation

Trunnionosis (mechanically assisted crevice corrosion) occurs at the modular head-neck junction. It typically presents with elevated cobalt levels disproportionate to chromium levels in patients with metal heads on titanium stems.

Question 74

A 75-year-old nursing home resident sustains a displaced femoral neck fracture. A cemented bipolar hemiarthroplasty is planned. During cement pressurization, the patient's blood pressure drops precipitously and end-tidal CO2 decreases. Which of the following is the most important prophylactic measure to prevent this?

Explanation

Bone cement implantation syndrome (BCIS) is characterized by hypoxia, hypotension, and cardiovascular collapse. Thorough lavage and venting of the femoral canal reduce intramedullary pressure and the risk of marrow embolization.

Question 75

A 28-year-old woman sustains a non-displaced femoral neck fracture. She undergoes in situ fixation with three cannulated screws. What is the most significant factor predicting the development of osteonecrosis (AVN) of the femoral head in this patient?

Explanation

The initial degree of fracture displacement is the most critical prognostic factor for the development of osteonecrosis following a femoral neck fracture. Capsulotomy and timing have not been consistently proven to alter AVN rates in non-displaced fractures.

Question 76

An 80-year-old man falls and sustains a basicervical femoral neck fracture. Which of the following fixation methods is biomechanically most appropriate for this fracture pattern?

Explanation

Basicervical femoral neck fractures are biomechanically unstable and behave similarly to intertrochanteric fractures. They are best treated with a sliding hip screw or cephalomedullary nail rather than multiple cancellous screws.

Question 77

Three weeks after a primary total hip arthroplasty via a posterior approach, a 65-year-old woman presents with sudden hip pain and shortening of the limb. Radiographs show a posterior dislocation. Closed reduction is successful. What is the most appropriate initial management?

Explanation

For a first-time posterior dislocation early after THA without component malposition, closed reduction followed by nonoperative management with an abduction brace and strict adherence to hip precautions is the standard initial treatment.

Question 78

A 68-year-old man presents with a Vancouver B2 periprosthetic femur fracture around his uncemented total hip arthroplasty 6 years after the index procedure. Radiographs show a fracture around a loose stem with adequate distal bone stock. What is the treatment of choice?

Explanation

A Vancouver B2 fracture involves a loose stem with good bone stock. The standard of care is revision arthroplasty using a long, diaphyseal-engaging stem (extensively porous-coated or fluted tapered) bypassing the fracture.

Question 79

When evaluating an anteroposterior pelvis radiograph to assess acetabular component positioning post-total hip arthroplasty, the /"safe zone/" for acetabular abduction (inclination) and anteversion, as historically described by Lewinnek, is:

Explanation

The Lewinnek safe zone for acetabular component placement in THA is historically defined as an inclination (abduction) of 40 degrees (+/- 10 degrees) and an anteversion of 15 degrees (+/- 10 degrees).

Question 80

A 70-year-old man undergoes a total hip arthroplasty via a direct anterior approach. Postoperatively, he complains of numbness and a burning sensation over the anterolateral aspect of his thigh. Motor function is completely intact. Which nerve was most likely stretched or injured?

Explanation

The lateral femoral cutaneous nerve is at risk during the direct anterior approach to the hip. Injury results in meralgia paresthetica, presenting as sensory deficits or burning pain over the anterolateral thigh with no motor weakness.

Question 81

You are reviewing a radiograph of a 62-year-old female who sustained a fall. The radiograph reveals a Garden I femoral neck fracture. Which of the following best describes the classical radiographic appearance of this fracture type?

Explanation

In the Garden classification of femoral neck fractures, a Garden I fracture is classically described as an incomplete, valgus-impacted fracture on the anteroposterior radiograph.

Question 82

A 50-year-old woman undergoes a total hip arthroplasty via a posterior approach. During the approach, the short external rotators are released. The surgeon must be particularly careful to protect the sciatic nerve, which typically exits the pelvis:

Explanation

The sciatic nerve exits the pelvis through the greater sciatic foramen, typically emerging inferior to the piriformis muscle before traveling deep to the gluteus maximus.

Question 83

A 25-year-old man sustains a displaced transcervical femoral neck fracture. Which of the following fixation constructs provides the greatest biomechanical stability for this high-shear fracture pattern?

Explanation

In young adults with displaced, high-shear femoral neck fractures (Pauwels III), a sliding hip screw with a derotation screw provides superior biomechanical stability compared to parallel cannulated screws. This construct better resists vertical shear forces and decreases the rate of nonunion.

Question 84

An active, independent 72-year-old woman sustains a displaced femoral neck fracture. Compared to bipolar hemiarthroplasty, treatment with total hip arthroplasty (THA) is most closely associated with which of the following outcomes?

Explanation

In active elderly patients with displaced femoral neck fractures, THA is associated with better long-term functional outcomes and lower revision rates compared to hemiarthroplasty. However, THA carries a higher risk of postoperative dislocation, longer operative times, and increased blood loss.

Question 85

A 65-year-old man presents with groin pain 5 years after undergoing a metal-on-polyethylene total hip arthroplasty with a large diameter (36 mm) metal head. Aspiration yields cloudy fluid with negative cultures. MRI with metal artifact reduction shows a solid pseudotumor. What is the most likely cause?

Explanation

Mechanically assisted crevice corrosion (trunnionosis) can occur at the modular head-neck junction, particularly with large metal heads on standard trunnions. It can present with adverse local tissue reactions (ALTR) or pseudotumors despite a non-metal-on-metal articulation.

Question 86

A 30-year-old male presents with a nondisplaced femoral neck fracture. Which of the following is the most compelling rationale for performing a hip capsulotomy during surgical fixation?

Explanation

The primary rationale for capsulotomy in young patients with femoral neck fractures is to decompress the intracapsular hematoma. This reduces elevated intra-articular pressure, which may improve residual blood flow to the femoral head and theoretically reduce the risk of avascular necrosis.

Question 87

A 45-year-old man underwent closed reduction and percutaneous pinning for a displaced femoral neck fracture 8 months ago. He now complains of progressive groin pain. Radiographs reveal varus collapse and fracture nonunion with a viable femoral head on MRI. What is the most appropriate definitive management?

Explanation

In a young patient with a femoral neck nonunion and a viable femoral head, a valgus intertrochanteric osteotomy is the treatment of choice. It converts shear forces into compressive forces, promoting fracture healing and preserving the native joint.

Question 88

During a direct anterior approach to the hip for total hip arthroplasty, the ascending branch of the lateral femoral circumflex artery is typically ligated. In what intermuscular interval is this approach performed?

Explanation

The direct anterior approach (Smith-Petersen interval) utilizes the true internervous plane between the tensor fasciae latae (superior gluteal nerve) and the sartorius (femoral nerve). The ascending branch of the lateral femoral circumflex artery crosses this interval and must be ligated for exposure.

Question 89

When utilizing three parallel cannulated screws for the fixation of a femoral neck fracture, what configuration provides the maximum biomechanical stability?

Explanation

The most biomechanically stable construct for cannulated screw fixation of a femoral neck fracture is an apex-distal (inverted) triangle. The screws should be spread as far apart as possible, resting against the inferior, anterior, and posterior cortices to maximize cortical support.

Question 90

A patient undergoes a posterior approach total hip arthroplasty. Postoperatively, the patient experiences recurrent anterior dislocations. Which of the following component malpositions is most likely responsible?

Explanation

Anterior hip dislocations after THA are typically caused by excessive combined anteversion, which includes excessive acetabular anteversion or excessive femoral anteversion. Excessive retroversion typically predisposes a patient to posterior dislocation.

Question 91

A 68-year-old male sustains a basicervical femoral neck fracture. Which of the following fixation methods is most appropriate due to the inherent biomechanical instability of this specific fracture pattern?

Explanation

Basicervical femoral neck fractures are considered rotationally and axially unstable, behaving more like extracapsular intertrochanteric fractures. A sliding hip screw (often with a derotation screw) or a cephalomedullary nail provides superior fixation compared to multiple cannulated screws.

Question 92

Following a total hip arthroplasty, a patient has a completely stable hip but complains that the operative leg feels 1.5 cm longer. Intraoperative templating was accurate. Which of the following adjustments during surgery would have corrected this leg length discrepancy without compromising abductor tension?

Explanation

To decrease leg length while maintaining abductor tension (offset), the surgeon should use a shorter femoral head (to drop leg length) while simultaneously using a high-offset stem to restore the horizontal distance. This prevents postoperative abductor laxity and instability.

Question 93

An 81-year-old woman with a displaced femoral neck fracture is undergoing a cemented bipolar hemiarthroplasty. During the pressurization of the cement and insertion of the femoral stem, she experiences sudden hypoxia, hypotension, and right heart failure. What is the primary pathophysiologic mechanism of this complication?

Explanation

Bone cement implantation syndrome (BCIS) is characterized by hypoxia and hypotension during cementation. It is primarily caused by the embolization of marrow fat, air, and bone debris into the pulmonary circulation due to high intramedullary pressures during cement pressurization and stem insertion.

Question 94

Which of the following vessels is the principal source of blood supply to the weight-bearing dome of the femoral head, and is most at risk in a displaced intracapsular femoral neck fracture?

Explanation

The medial femoral circumflex artery (MFCA) gives rise to the lateral epiphyseal artery, which provides the majority of the blood supply to the weight-bearing dome of the femoral head. This ascending vessel is frequently disrupted or kinked in displaced femoral neck fractures.

Question 95

A 55-year-old man with a history of ankylosing spondylitis is scheduled for a bilateral total hip arthroplasty. To prevent heterotopic ossification, which of the following prophylactic regimens is most appropriate?

Explanation

Patients with ankylosing spondylitis are at high risk for heterotopic ossification (HO) following THA. Prophylaxis with single-fraction localized radiation therapy (700-800 cGy) within 24-48 hours postoperatively or oral indomethacin for 2 to 6 weeks is highly effective in preventing HO.

Question 96

A 78-year-old man presents with a displaced femoral neck fracture. He is on clopidogrel for a drug-eluting stent placed 2 years ago. Cardiology clears him for surgery. What is the optimal timing for his hemiarthroplasty to minimize mortality?

Explanation

Delaying hip fracture surgery beyond 48 hours is associated with significantly increased 30-day and 1-year mortality. Current guidelines recommend proceeding with surgery within 24-48 hours, even in patients taking clopidogrel, as the benefits of early mobilization outweigh the risks of bleeding.

Question 97

A 75-year-old woman sustains a fall. Radiographs show a valgus-impacted femoral neck fracture (Garden I). She is currently ambulating with minimal pain. What is the recommended treatment?

Explanation

Garden I (valgus-impacted) femoral neck fractures have a high risk of secondary displacement if treated conservatively. In situ fixation with parallel cannulated screws is the standard of care to prevent displacement and promote healing, even in the elderly.

Question 98

Following a complex total hip arthroplasty via a posterior approach for developmental dysplasia of the hip (DDH), the patient is noted to have a foot drop. They cannot dorsiflex the great toe but have preserved plantar flexion. Which nerve division is most likely injured, and what is the typical mechanism?

Explanation

The peroneal division of the sciatic nerve is the most commonly injured nerve during THA, particularly in cases involving significant limb lengthening (e.g., DDH). It is more susceptible to stretch injury than the tibial division because it is tethered at the fibular head and has less supportive connective tissue.

Question 99

A 42-year-old active male underwent a ceramic-on-ceramic total hip arthroplasty 3 years ago. He presents with an audible 'squeaking' noise from the hip during deep flexion, though he denies any pain. Radiographs show no loosening. What is the most common factor associated with this phenomenon?

Explanation

Squeaking is a known complication of ceramic-on-ceramic bearings. It is most strongly associated with component malposition (e.g., steep acetabular cup angle or excessive anteversion), which leads to edge loading, loss of fluid film lubrication, and stripe wear.

Orthopedic Board Review Set 675: 100 MCQs for ABOS, OITE, FRCS – Hip Focus

AAOS Hip MCQs (Set 3): Femoral Neck Fractures & Arthroplasty | ABOS Board Review

Key Takeaway

AAOS Hip MCQs (Set 3): Femoral Neck Fractures & Arthroplasty | ABOS Board Review

Chapter Index