Orthopedic Hip MCQs 2026 | Board Review & Answers

Question 1

Figure 1 shows the radiograph of a 68-year-old man who underwent revision hip arthroplasty with impaction grafting of the femur and cementing of a tapered component into the graft 2 years ago. The patient remains symptom-free. Which of the following best describes the most likely histologic appearance of the proximal femur if a biopsy was performed?

Explanation

The radiograph shows three zones: an outer regenerated cortical layer, an interface zone consisting of viable trabecular bone and occasional particles of bone cement, and an inner layer of necrotic bone embedded in cement. No fibrous membrane is noted, and there is no direct contact of cement with native bone. Based on these findings, it is believed that the middle layer is the result of incorporation of the allograft with further remodeling. Nelissen RG, Bauer TW, Weidenhielm LR, LeGolvan DP, Mikhail WE: Revision hip arthroplasty with the use of cement and impaction grafting: Histological analysis of four cases. J Bone Joint Surg Am 1995;77:412-422.

Question 2

Compared with cobalt-chromium, the biomechanical properties of titanium on polyethylene articulation in total hip replacement result in

Explanation

The surface hardness of titanium is low compared with that of cobalt-chromium alloys. Titanium articulations are easily scratched, resulting in a significantly increased rate of wear and debris production. The wear and resulting lysis can also result in an increased rate of loosening. Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 449-486. Agins HJ, Alcock NW, Bansal M, et al: Metallic wear in failed titanium-alloy total hip replacements: A histological and quantitative analysis. J Bone Joint Surg Am 1988;70:347-356.

Question 3

What is the most common reason for reoperation in total knee arthroplasty?

Explanation

Patellar problems currently constitute the largest number of complications after total knee arthroplasty, affecting between 8% and 35% of patients. These problems include patellar instability, fracture, component loosening, surface erosion, and pain. Malalignment, as an isolated reason for revision, is uncommon, yet it contributes to accelerated wear of the components. Joint instability affects up to 6% of patients, and the infection rate in knee arthroplasty is around 1% to 2%. Blasier RB, Matthews LS: Complications of prosthetic knee arthroplasty, in Epps CH (ed): Complications in Orthopaedic Surgery. Philadelphia, PA, JP Lippincott, 1994, pp 1066-1069. Rand JA: The patellofemoral joint in total knee arthroplasty. J Bone Joint Surg Am 1994;76:612-620.

Question 4

Which of the following factors is most commonly associated with mechanical failure of a cemented total hip arthroplasty?

Explanation

Varus position of the stem is most commonly associated with failure of the cemented femoral component because of association with an inadequate cement mantle in the proximal medial and distal lateral zones. An inadequate cement mantle and obesity have been associated with increased loosening but not as frequently as a varus deformity. The influences of gender and osteoporotic bone on the outcome of cemented femoral components have not been established. Maloney WJ III: Primary cemented total hip arthroplasty, in Callaghan JJ, Dennis DA, Paprosky WG, Rosenberg AG (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 179-189.

Question 5

Figure 2 shows the radiograph of a 72-year-old woman who reports pain after a fall. History includes several years of increasing thigh pain and limb shortening. Management consisting of an extensive work-up for infection reveals normal laboratory studies, a positive bone scan, and a negative hip aspiration. What is the most likely etiology of this complication?

Explanation

The patient has a midstem periprosthetic fracture, which commonly results in loosening of the prosthesis. Patients who have a large amount of bone loss may require an allograft with the surgical reconstruction. Although the patient reported a fall, her history is also consistent with preexisting loosening of the prosthesis. Chronic infection has been shown in up to 16% of these fractures; however, the patient's work-up revealed no infection. Garbuz DS, Masri BA, Duncan CP: Periprosthetic fractures of the femur: Principles of prevention and management, in Cannon WD Jr (ed): Instructional Course Lectures 47. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 237-242. Bethea JS III, DeAndrade JR, Fleming LL, Lindenbaum SD, Welch RB: Proximal femoral fractures following total hip arthroplasty. Clin Orthop 1982;170:95-106.

Question 6

Figures 3a through 3c show the radiographs and bone scan of a patient who reports increasing pain associated with activity for the past several months. Laboratory studies show an erythrocyte sedimentation rate of 14 mm/h and a C-reactive protein level of 0.4. Aspiration is negative for infection. Management should consist of

Explanation

3b 3c The radiographs show polyethylene wear, but exchange of this will not necessarily provide pain relief. The presence of pain suggests the possibility of occult loosening, and the surgeon must be prepared for this option intraoperatively. There is little evidence of infection. Rand JA, Peterson LF, Bryan RS, Ilstrup DM: Revision total knee arthroplasty, in Anderson LD (ed): Instructional Course Lectures XXXV. Park Ridge, IL, American Academy of Orthopaedic Surgeons, 1986, pp 305-318.

Question 7

Which of the following studies has the highest sensitivity and specificity in diagnosis of osteonecrosis of the femoral head?

Explanation

An MRI scan is both highly sensitive and specific for the evaluation of osteonecrosis. The measurement of increased intraosseous pressure can be technically difficult and the results have been variable. Plain radiographs can be normal early in the progression of osteonecrosis of the femoral head. The technetium Tc 99m bone scan is a very sensitive test. However, it is not specific; increased uptake can be noted in patients with arthritis, neoplastic disease, fracture, or sepsis. In addition, because of bilaterality, the frequency of false-negative scans is relatively high. Steinberg ME: Early diagnosis, evaluation, and staging of osteonecrosis, in Jackson DW (ed): Instructional Course Lectures 43. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 513-518.

Question 8

Figure 4 shows the AP radiograph of a 28-year-old woman who has had moderate pain in the left hip for the past year. Nonsurgical management has failed to provide relief. She denies any history of hip pain, pathology, or trauma. Management should consist of

Explanation

The radiograph shows developmental dysplasia of the hip with the hip reduced and congruent. The treatment of choice is a periacetabular osteotomy because it can improve hip biomechanics and prolong the function of the hip joint. This procedure should be performed prior to the development of severe degenerative changes. Observation will not alter the patient's natural history or the biomechanics of the hip. A total hip arthroplasty should be delayed until severe degenerative changes are present. A Chiari osteotomy is a salvage osteotomy used for a noncongruent subluxated hip. A Pemberton osteotomy requires an open triradiate cartilage; therefore, it is not an option in an adult. Trousdale RT, Ekkernkamp A, Ganz R, Wallrichs SL: Periacetabular and intertrochanteric osteotomy for the treatment of osteoarthrosis in dysplastic hips. J Bone Joint Surg Am 1995;77:73-85.

Question 9

What complication is most likely to develop after right total hip arthroplasty in the patient shown in Figure 5?

Explanation

The patient has hypertrophic arthritis, which is a strong risk factor for heterotopic bone formation. The remaining complications are possible but do not have the same significant risks. Goel A, Sharp DJ: Heterotopic bone formation after hip replacement: The influence of the type of osteoarthritis. J Bone Joint Surg Br 1991;73:255-257.

Question 10

In revision total hip arthroplasty, an acetabular reconstruction cage is best indicated for which of the following patterns of bone loss?

Explanation

Acetabular cage reconstruction is indicated in severe disruption of acetabular bone stock when a cementless acetabular component cannot be stabilized in intimate contact with a sufficient bed of structurally sound and viable host bone, with or without a structural graft. Cages are used in pelvic discontinuity where they provide a bridge between the ilium and the ischium, while supporting a cemented cup. All of the other scenarios are amenable to achieving an adequate rim fit for a cementless component, using a jumbo cup if necessary. Whiteside LA: Selection of acetabular component, in Steinberg ME, Garino JP (eds): Revision Total Hip Arthroplasty. Philadelphia, PA, Lippincott Williams and Wilkins, 1999, pp 209-220.

Question 11

Mechanical reduction of the pain associated with the condition shown in Figure 6 can be accomplished through the use of a cane on the contralateral side. Similarly, if this patient must carry any type of load in his or her arms, it should be carried

Explanation

Patients with diseased hips often must carry objects while walking, yet they are rarely instructed on which hand to use. The patient should be directed to carry the object on the ipsilateral side, just the opposite of the side he or she would use a cane. The cane pushes up on the weight of the body so that when the patient is carrying a load, the weight in the hand on the same side as the hip pushes up on the weight of the body, but now the patient has the fulcrum of the hip in between. Tan and associates mathematically determined the hip forces that result when a load is carried in the ipsilateral hand versus the contralateral hand. Using a free-body diagram of a single-leg supported stance, they found that when a load was carried in the contralateral hand, the resultant forces on the hip were increased considerably. Conversely, when the weight was carried in the ipsilateral hand, the forces were actually lower than when no weight was carried at all. Therefore, carrying a weight on the opposite side resulted in hip forces that were substantially greater than when the weight was carried on the same side.

Question 12

Figure 7 shows the AP radiograph of a 60-year-old man who has had pain in the thigh for past 6 months. History reveals that he underwent hip replacement 1 year ago. The radiographic changes are most likely the result of what process?

Explanation

The arrows in the radiograph point to circumferential radiolucencies that strongly support the diagnosis of septic loosening. Radiolucent lines that occur in such a short time are also typical of an infection. Garvin KL, Hanssen AD: Infection after total hip arthroplasty: Past, present, and future. J Bone Joint Surg Am 1995;77:1576-1588.

Question 13

Figure 8 shows the radiograph of a 72-year-old man who has had severe pain in the left hip for the past 3 weeks. History reveals alcohol abuse. The next most appropriate step should consist of

Explanation

The radiograph reveals destruction of the femoral head with loss of the articular cartilage. These findings are consistent with an infected hip, and aspiration will confirm the diagnosis. Although the patient could have advanced osteonecrosis, typically the cartilage interval is maintained and such destruction is rarely associated with osteonecrosis.

Question 14

Which of the following articulation couplings shows the lowest coefficient of friction as tested in the laboratory?

Explanation

Alumina ceramic is highly biocompatible when used as a biomaterial for joint arthroplasty implants. It has been shown to have good hardness, low roughness, and excellent wettability, therefore resulting in very low friction. However, it is expensive and limited reports have shown the problem of fracture on impact. The exact role for ceramic articulations is unknown at present. Cuckler JM, Bearcroft J, Asgian CM: Femoral head technologies to reduce polyethylene wear in total hip arthroplasty. Clin Orthop 1995;317:57-63.

Question 15

Which of the following is considered the best cementless acetabular reconstruction method when planning for total hip arthroplasty in a patient with developmental dysplasia of the hip (DDH)?

Explanation

Anatomic positioning of the acetabular component has been shown to be the optimal position for reconstruction of the acetabulum in total hip arthroplasty for DDH. The use of medialized component positioning has been shown to be successful at maximizing the host bone coverage and minimizing the use of bone graft to structurally support the acetabular component. A small acetabular component can be used successfully as long as the femoral head is also reduced in size to maintain the thickness of the acetabular polyethylene. High and lateral positioning for the acetabular reconstruction will result in an increase in the joint reaction forces. In addition, a high and lateral placement will not provide adequate bone to stabilize the reconstruction. Numair J, Joshi AB, Murphy JC, Porter ML, Hardinge K: Total hip arthroplasty for congenital dysplasia or dislocation of the hip: Survivorship analysis and long-term results. J Bone Joint Surg Am 1997;79:1352-1360. Dorr LD, Tawakkol S, Moorthy M, Long W, Wan Z: Medial protrusio technique for placement of a porous-coated, hemispherical acetabular component without cement in a total hip arthroplasty in patients who have acetabular dysplasia. J Bone Joint Surg Am 1999;81:83-92.

Question 16

Which of the following mechanisms is considered the most common cause of failure of osteoarticular allografts used for articular reconstruction?

Explanation

Mechanical loosening and infection can occur as complications after surgery, but the most common cause of osteoarticular allograft failure is graft collapse during revascularization. Clinical rejection because of an immune response is an unusual means of failure. Meyers MH, Akeson W, Convery FR: Resurfacing of the knee with fresh osteochondral allograft. J Bone Joint Surg Am 1989;71:704-713.

Question 17

When compared with a patient who has a subluxated hip, a patient with a dislocated hip who is undergoing acetabular reconstruction for developmental dysplasia of the hip will most likely have

Explanation

The rate of revision has been found to be significantly increased in patients with a dislocated hip preoperatively compared with patients with a subluxated hip. This may be the result of compromised acetabular bone stock. The rate of nerve palsy may be increased because of the greater degree of lengthening required to reduce the reconstructed hip. Numair J, Joshi AB, Murphy JC, Porter ML, Hardinge K: Total hip arthroplasty for congenital dysplasia or dislocation of the hip: Survivorship analysis and long-term results. J Bone Joint Surg Am 1997;79:1352-1360.

Question 18

The anticoagulant effect of the low-molecular-weight heparins (LMWH) is mediated by the binding affinity of antithrombin III to which of the following coagulation factors?

Explanation

Standard heparin mediates its anticoagulant effect largely through its interaction with antithrombin III. A conformational change in antithrombin III occurs that markedly accelerates its ability to inactivate the coagulation enzymes thrombin factor (II), factor Xa, and factor IXa. In contrast, LMWHs do not contain the necessary saccharide units to bind thrombin and antithrombin III simultaneously. The anticoagulant effect of LMWHs involves binding of antithrombin III to factor Xa.

Question 19

The primary purpose of obtaining the radiograph shown in Figure 9 is to assess

Explanation

The radiograph shows a faux profil view of the hip. The primary purpose of this view is to evaluate anterior coverage of the femoral head. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 455-492. Ganz R, Klaue K, Vinh TS, Mast JW: A new periacetabular osteotomy for the treatment of hip dysplasias: Technique and preliminary results. Clin Orthop 1988;232:26-36.

Question 20

Figure 10 shows the radiograph of an active 75-year-old woman who reports severe leg pain after a fall. Management should consist of

Explanation

The patient has a comminuted fracture of the proximal femur and joint space narrowing of the acetabulum. Therefore, the prosthesis should be converted to a total hip arthroplasty. Because there is extensive comminution, the revision stem should bypass the area of bone loss by two bone diameters. A hemiarthroplasty is not indicated because the patient has no acetabular cartilage. Open reduction and internal fixation may not stabilize the prosthesis. A resection arthroplasty or treatment in traction will not leave the patient with adequate function. Garbuz DS, Masri BA, Duncan CP: Periprosthetic fractures of the femur: Principles of prevention and management, in Cannon WD Jr (ed): Instructional Course Lectures 47. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 237-242.

Question 21

Which of the following procedures is considered most appropriate in patients with rheumatoid arthritis?

Explanation

Synovectomy of the knee prior to loss of articular cartilage has been shown to consistently relieve pain in patients with rheumatoid arthritis. Partial knee replacement will not arrest the process of joint destruction. Osteotomy of the hip has not been found to be a successful procedure in patients with rheumatoid arthritis. Hip arthrodesis should not be considered because of the multiarticular involvement in patients with rheumatoid arthritis. Core decompression of the hip has not been shown to save the femoral head because the necrosis appears to occur simultaneously with the inflammatory joint process. Granberry WM, Brewer EJ Jr: Early surgery in juvenile rheumatoid arthritis, in Calundruccio RA (ed): Instructional Course Lectures XXIII. St Louis, MO, CV Mosby, 1974, pp 32-37.

Question 22

In a patient who has rheumatoid arthritis with acetabular protrusion, what is the best biomechanical position for the cup with respect to the preoperative center of rotation?

Explanation

Acetabular protrusion in patients with rheumatoid arthritis moves the center of hip rotation medially and posteriorly. Positioning of the acetabular component in a patient with protrusion is best accomplished in the normal (anterior and inferior) position and not in a protruded position. This has been shown both clinically and in a finite-element analysis. Any medial positioning will produce impingement of the prosthesis neck on the rim, and superior placement produces improper hip mechanics. Crowninshield RD, Brand RA, Pedersen DR: A stress analysis of acetabular reconstruction in protrusio acetabuli. J Bone Joint Surg Am 1983;65:495-499.

Question 23

Figures 11a and 11b show the radiographs of a 50-year-old man who was struck by a car. Treatment should consist of

Explanation

11b The patient has a displaced femoral neck fracture. Although the treatment remains controversial, most clinicians advocate either a closed or open reduction in younger active patients. Achieving an anatomic reduction is necessary to avoid loss of reduction, nonunion, or osteonecrosis. An acceptable reduction may have up to 15 degrees of valgus angulation and 10 degrees of posterior angulation. Parallel multiple screws or pins are the most common method of internal fixation. Prosthetic replacement is generally reserved for older and less active individuals. Callaghan JJ, Dennis DA, Paprosky WG, et al (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 97-108.

Question 24

One advantage of using onlay strut allograft in femoral revision surgery is that it can

Explanation

Onlay grafts can provide more structural support than morcellized grafts. They are more easily incorporated into the host femur than bulk segmental total femur allografts; however, the incorporation is never complete. The use of onlay grafts is principally directed at addressing segmental defects of the femur; their use can be applied with either cementless or cement fixation of the femoral stem. Emerson RH Jr, Malinin TI, Cuellar AD, Head WC, Peters PC: Cortical strut allografts in the reconstruction of the femur in revision total hip arthroplasty: A basic science and clinical study. Clin Orthop 1992;285:35-44. Pak JH, Paprosky WG, Jablonsky WS, Lawrence JM: Femoral strut allografts in cementless revision total hip arthroplasty. Clin Orthop 1993;295:172-178.

Question 25

Which of the following methodologies has been proven to be effective in reducing the use of homologous blood transfusion following total hip arthroplasty (THA)?

Explanation

A variety of methodologies have been used to decrease the need for homologous blood transfusions following THA. Some of the effective strategies include preoperative donation of autologous units, intraoperative salvage and recycling, preoperative injection of erythropoietin, and regional anesthesia. Cementless fixation and use of wound drains have been shown to increase the blood loss with THA. Huo MH, Paly WL, Keggi KJ: Effect of preoperative autologous blood donation and intraoperative and postoperative blood recovery on homologous blood transfusion requirement in cementless total hip replacement operation. J Am Coll Surg 1995;180:561-567. Bierbaum BE, Callaghan JJ, Galante JO, Rubash HE, Tooms RE, Welch RB: An analysis of blood management in patients having a total hip or knee arthroplasty. J Bone Joint Surg Am 1999;81:2-10.

Question 26

Increasing femoral offset during total hip arthroplasty, without altering leg length, results in which of the following biomechanical changes?

Explanation

Increasing femoral offset increases the abductor moment arm, which decreases the required abductor muscle force and subsequently decreases the overall joint reaction force. However, it does increase the bending moment on the femoral stem.

Question 27

A 62-year-old man presents with progressive groin pain 5 years after receiving a metal-on-polyethylene total hip arthroplasty. Laboratory tests reveal a serum cobalt level of 12 ppb and a normal serum chromium level. Inflammatory markers are normal. What is the most likely etiology?

Explanation

Trunnionosis occurs via mechanically assisted crevice corrosion at the modular head-neck junction. This typically presents with isolated elevations of serum cobalt with normal chromium in metal-on-polyethylene implants.

Question 28

Irradiation of ultra-high molecular weight polyethylene (UHMWPE) is commonly performed to improve wear characteristics. What is the primary disadvantage of increasing the irradiation dose during the cross-linking process?

Explanation

Highly cross-linked polyethylene significantly improves wear resistance but at the cost of diminished mechanical properties. The primary disadvantage is a reduction in fatigue strength, ductility, and fracture toughness.

Question 29

A 70-year-old woman with a T10-to-pelvis posterior spinal fusion undergoes a total hip arthroplasty. Because of her spinal fusion, her pelvis is unable to tilt posteriorly when she transitions from standing to sitting. To minimize the risk of posterior dislocation, how should the acetabular component positioning be adjusted?

Explanation

Patients with stiff spinopelvic constructs (unable to posteriorly tilt during sitting) fail to increase functional acetabular anteversion in flexion. Surgeons must compensate by increasing the resting anteversion of the acetabular cup to prevent posterior dislocation.

Question 30

During a direct anterior approach for total hip arthroplasty, the surgeon develops the superficial internervous plane. Which two nerves supply the muscles that form the boundaries of this specific interval?

Explanation

The superficial interval of the direct anterior approach is between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The deep interval is between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 31

A 78-year-old woman sustains a periprosthetic femur fracture around a cemented femoral stem. Radiographs demonstrate a fracture at the tip of the stem with evidence of cement mantle fracture and stem subsidence. The distal bone stock is adequate. According to the Vancouver classification, what is the most appropriate management?

Explanation

This is a Vancouver B2 fracture, characterized by a fracture around a loose stem with adequate bone stock. The standard of care is revision arthroplasty using a long stem that bypasses the fracture by at least two cortical diameters.

Question 32

A 55-year-old woman presents with hip pain and a palpable groin mass 6 years after a metal-on-metal hip resurfacing. Histologic examination of the periarticular tissue is most likely to reveal which of the following predominant features?

Explanation

Adverse local tissue reactions to metal debris (ALVAL) are characterized by a delayed type IV hypersensitivity response. Histology shows a predominant perivascular lymphocytic infiltrate, massive tissue necrosis, and macrophages containing metal particles.

Question 33

Cam-type femoroacetabular impingement (FAI) is anatomically characterized by a reduced head-neck offset. During hip flexion, this morphology most commonly causes which of the following specific intra-articular injury patterns?

Explanation

Cam impingement exerts shear forces on the anterosuperior acetabular rim during flexion and internal rotation. This classically leads to "outside-in" chondral delamination and subsequent labral detachment from the articular cartilage.

Question 34

A 45-year-old highly active man underwent a ceramic-on-ceramic total hip arthroplasty 3 years ago. He now complains of a loud squeaking noise from the hip when bending and walking, without significant pain. What is the most likely biomechanical cause of this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic hips is heavily associated with edge loading, often due to component malpositioning (e.g., steep cup inclination or excessive retroversion). This edge loading causes localized stripe wear and micro-separation, leading to the audible noise.

Question 35

Increasing the femoral offset in total hip arthroplasty results in which of the following biomechanical changes?

Explanation

Increasing femoral offset lengthens the abductor moment arm. This improves abductor mechanical advantage, requiring less muscle force to stabilize the pelvis, which consequently decreases the overall joint reaction force on the hip.

Question 36

A 65-year-old female is evaluated for recurrent posterior THA dislocations. Radiographs demonstrate a stiff lumbar spine with loss of normal spinopelvic mobility. When transitioning from standing to sitting, how does a stiff spine abnormally affect acetabular version?

Explanation

Normally, moving from standing to sitting involves lumbar flexion and posterior pelvic tilt, which increases acetabular anteversion to accommodate hip flexion. A stiff spine prevents this posterior tilt, leaving the cup relatively retroverted and prone to posterior dislocation.

Question 37

A 72-year-old male presents with a periprosthetic femur fracture around a cemented femoral stem 10 years post-THA. Radiographs show a fracture extending from the lesser trochanter to the distal tip of the stem, with a radiographically loose stem and poor bone stock. What is the most appropriate management?

Explanation

This is a Vancouver B3 fracture, characterized by a fracture around a loose stem with poor bone stock. A fluted, tapered modular stem or proximal femoral replacement is indicated to bypass the defect and achieve diaphyseal fixation.

Question 38

Which of the following radiographic findings is most characteristic of a pincer-type femoroacetabular impingement (FAI)?

Explanation

The crossover sign indicates cranial focal acetabular retroversion where the anterior wall crosses the posterior wall, a hallmark of pincer-type FAI. The other options describe features of cam-type FAI.

Question 39

According to the 2018 International Consensus Meeting criteria, which of the following is considered a major criterion, diagnostic in itself, for periprosthetic joint infection (PJI)?

Explanation

A sinus tract communicating with the joint or two positive cultures with the same organism are considered major criteria that definitively diagnose a periprosthetic joint infection.

Question 40

A 35-year-old male with a history of systemic lupus erythematosus treated with corticosteroids presents with groin pain. An MRI confirms stage II osteonecrosis of the right femoral head with no evidence of subchondral collapse. He has a 30% involvement of the weight-bearing portion. Which is the most appropriate initial surgical intervention?

Explanation

Core decompression is the standard, least invasive initial surgical treatment for pre-collapse (Stage I or II) osteonecrosis of the femoral head to reduce intraosseous pressure and promote revascularization.

Question 41

Ceramic-on-ceramic (CoC) bearing surfaces in total hip arthroplasty are characterized by which of the following compared to metal-on-polyethylene?

Explanation

Ceramic-on-ceramic bearings offer extremely low volumetric wear and excellent lubrication but carry a distinct risk of catastrophic ceramic fracture and joint squeaking compared to polyethylene bearings.

Question 42

A 6-week-old female infant is treated with a Pavlik harness for developmental dysplasia of the hip. At the 3-week follow-up, ultrasound shows the hip remains dislocated. What is the most appropriate next step in management?

Explanation

Prolonged use of a Pavlik harness in a persistently dislocated hip can lead to Pavlik harness disease and AVN. If unreduced after 3 to 4 weeks, it should be abandoned in favor of closed reduction and spica casting.

Question 43

A 13-year-old obese boy presents with a mild slipped capital femoral epiphysis (SCFE) of the left hip. When is prophylactic pinning of the contralateral, asymptomatic hip most strongly indicated?

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with underlying endocrinopathies (e.g., hypothyroidism) or metabolic bone diseases due to an extremely high risk of bilateral involvement.

Question 44

A 4-year-old boy presents with right hip pain, refusal to bear weight, a temperature of 38.8 C (101.8 F), an ESR of 45 mm/hr, and a serum WBC count of 13,000/mm3. According to the Kocher criteria, what is the probability that he has septic arthritis?

Explanation

The four Kocher criteria are non-weight-bearing, temperature >38.5 C, ESR >40 mm/hr, and WBC >12,000. With all 4 criteria present, the probability of septic arthritis is approximately 99%.

Question 45

Which of the following is considered a 'head-at-risk' sign in Legg-Calve-Perthes disease?

Explanation

Catterall's 'head-at-risk' signs indicate a poor prognosis and include Gage's sign, lateral subluxation of the femoral head, calcification lateral to the epiphysis, and a horizontal growth plate.

Question 46

A 40-year-old male sustains a pelvic ring injury. Radiographs show a widened pubic symphysis of 3.5 cm and disruption of the anterior sacroiliac ligaments with intact posterior sacroiliac ligaments. What type of injury is this according to the Young and Burgess classification?

Explanation

An APC II injury involves symphyseal widening >2.5 cm and disruption of the anterior SI ligaments but with intact posterior SI ligaments, causing rotational instability while maintaining vertical stability.

Question 47

A 30-year-old male sustains a vertically oriented (Pauwels type III) femoral neck fracture. Which of the following fixation constructs is biomechanically optimal to resist the high shear forces in this fracture pattern?

Explanation

Pauwels type III fractures are subject to significant shear forces. A fixed-angle device such as a sliding hip screw (often supplemented with a derotational screw) provides superior biomechanical stability against varus collapse compared to multiple cancellous screws alone.

Question 48

Following a primary total hip arthroplasty via a direct anterior approach, the patient complains of numbness over the anterolateral aspect of the thigh. Motor function of the lower extremity is intact. Which nerve is most likely affected?

Explanation

The direct anterior approach utilizes the internervous plane between the tensor fasciae latae and sartorius. The lateral femoral cutaneous nerve is at highest risk, leading to meralgia paresthetica if injured.

Question 49

A 65-year-old patient with a ceramic-on-ceramic total hip arthroplasty (THA) presents with an audible squeak with walking. Which factor is most strongly associated with this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading, often due to acetabular cup malposition (such as excessive steepness or anteversion). This disrupts fluid film lubrication and causes stripe wear and subsequent squeaking.

Question 50

Which of the following is a recognized unique complication of dual mobility articulations in total hip arthroplasty?

Explanation

Intra-prosthetic dislocation is a unique complication of dual mobility cups. It occurs when the inner femoral head dislocates from the captive mobile polyethylene liner, often due to wear or failure of the retentive rim.

Question 51

A 30-year-old sustains a displaced, vertical (Pauwels type III) femoral neck fracture. Biomechanical studies indicate which of the following fixation constructs provides the greatest stability for this fracture pattern?

Explanation

Pauwels type III fractures have a high degree of vertical shear. A fixed-angle device such as a dynamic hip screw (DHS) supplemented with an anti-rotation screw provides superior biomechanical stability compared to multiple cancellous screws.

Question 52

Review the clinical scenario.

A 75-year-old female sustains a fall and presents with thigh pain. Radiographs reveal a periprosthetic fracture around a well-fixed cementless femoral stem, extending just distal to the lesser trochanter. According to the Vancouver classification, what is the most appropriate management?

Explanation

A fracture around a well-fixed stem that is distal to the trochanters but proximal to the stem tip is a Vancouver B1 fracture. The standard of care is open reduction and internal fixation, typically utilizing a plate and cerclage cables.

Question 53

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a major criterion for the diagnosis of periprosthetic joint infection (PJI) in a total hip arthroplasty?

Explanation

The 2018 ICM criteria dictate that a sinus tract communicating with the joint or two positive periprosthetic cultures with phenotypically identical organisms are major criteria. These definitively diagnose a periprosthetic joint infection.

Question 54

A 24-year-old male hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. Radiographs show an alpha angle of 70 degrees on the lateral view. The pathophysiologic mechanism of joint damage in this condition primarily involves:

Explanation

Cam-type femoroacetabular impingement causes shear forces at the anterosuperior acetabulum. This characteristically leads to early chondral delamination at the chondrolabral junction.

Question 55

The direct anterior approach for total hip arthroplasty utilizes an internervous plane between which two muscles?

Explanation

The direct anterior (Smith-Petersen) approach uses a superficial internervous plane between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve).

Question 56

During the single-leg stance phase of gait, the hip abductor musculature must generate a force approximately how many times body weight to maintain a level pelvis?

Explanation

To counteract the moment arm of body weight acting on the center of gravity during single-leg stance, the hip abductors must exert a force roughly 2.5 times body weight. This results in a total joint reaction force of about 3.5 times body weight.

Question 57

Review the image provided.

A 35-year-old male with a history of high-dose corticosteroid use presents with severe groin pain. An MRI shows a subchondral crescent sign without subchondral collapse or joint space narrowing. What is the most appropriate initial surgical intervention to preserve the joint?

Explanation

In pre-collapse osteonecrosis of the femoral head (characterized by a crescent sign but no articular flattening), core decompression is indicated. It aims to relieve venous pressure, restore vascularity, and potentially halt progression.

Question 58

A 60-year-old female with a metal-on-metal total hip arthroplasty performed 8 years ago presents with vague groin pain and a palpable anterior thigh mass. MRI with metal artifact reduction sequence (MARS) shows a large cystic periarticular collection. Histologic evaluation of the periprosthetic tissue would most likely reveal:

Explanation

Adverse local tissue reactions (ALTR) associated with metal-on-metal implants or trunnionosis are characterized histologically by aseptic lymphocytic vasculitis-associated lesions (ALVAL). This features extensive macrophage infiltration containing metal wear debris.

Question 59

In a patient undergoing total hip arthroplasty, dynamic spinopelvic assessment reveals a stiff, fused lumbar spine in a kyphotic position. How does this condition affect the functional position of the acetabulum when the patient transitions from standing to sitting?

Explanation

In a stiff lumbar spine, the pelvis fails to undergo normal posterior tilt when sitting. This lack of posterior tilt means the acetabulum does not gain functional anteversion, risking anterior impingement and subsequent posterior dislocation.

Question 60

Which of the following component combinations in total hip arthroplasty is associated with the highest risk of mechanically assisted crevice corrosion (trunnionosis) at the head-neck junction?

Explanation

Large diameter metal heads and increased head-neck offset lengths increase the frictional torque and bending moments at the trunnion. Combining a cobalt-chromium head with a titanium stem significantly exacerbates mechanically assisted crevice corrosion.

Question 61

A 45-year-old female with secondary osteoarthritis due to developmental dysplasia of the hip is planned for total hip arthroplasty. Preoperative radiographs show a high hip dislocation with 75-100% proximal migration of the femoral head relative to the true acetabulum. Which Crowe classification does this represent, and what is a commonly necessary surgical step?

Explanation

Crowe III dysplasia is defined by 75-100% proximal migration of the femoral head. Placement of the acetabular component at the true center of rotation often requires a subtrochanteric shortening osteotomy to safely reduce the hip without causing sciatic nerve traction injury.

Question 62

A 65-year-old woman is evaluated for a total hip arthroplasty. She has a history of L3-S1 lumbar fusion. Sitting and standing lateral radiographs show a change in pelvic tilt of 5 degrees. How should the acetabular cup be positioned compared to a patient with normal spinopelvic mobility?

Explanation

A stiff lumbar spine (change in pelvic tilt <10 degrees) prevents normal posterior pelvic rollback during sitting. This increases the risk of anterior impingement and posterior dislocation; therefore, the cup should be placed in increased anteversion and inclination.

Question 63

A 60-year-old man presents with groin pain 5 years after a total hip arthroplasty with a metal-on-polyethylene bearing and a titanium stem with a cobalt-chromium head. MRI with metal artifact reduction shows a solid pseudotumor, but inflammatory markers and aspiration are normal. What is the most likely etiology?

Explanation

Mechanically assisted crevice corrosion (trunnionosis) occurs at the modular head-neck junction of a titanium stem and cobalt-chromium head. It can lead to an adverse local tissue reaction (ALTR) and pseudotumor formation even with metal-on-polyethylene bearings.

Question 64

A 75-year-old woman sustains a fall 8 years after a primary cemented total hip arthroplasty. Radiographs show a spiral fracture around the tip of the stem. The stem is loose, but the proximal bone stock is of good quality. What is the most appropriate management?

Explanation

This is a Vancouver B2 periprosthetic fracture (fracture around the stem, loose stem, adequate bone stock). The gold standard treatment is revision to a long, distally fixing (fully porous-coated or fluted tapered) uncemented stem, bypassing the fracture site.

Question 65

Which of the following total hip arthroplasty bearing surfaces is associated with the lowest volumetric wear rate but carries a risk of squeaking and catastrophic component fracture?

Explanation

Ceramic-on-ceramic bearings offer the lowest volumetric wear and are highly scratch-resistant. However, they carry unique risks including squeaking, component fracture, and stripe wear.

Question 66

According to the 2018 International Consensus Meeting on Periprosthetic Joint Infection (PJI), which of the following is considered a major criterion that is sufficient to diagnose PJI on its own?

Explanation

The 2018 ICM criteria define a major criterion as either a sinus tract communicating with the joint or two positive periprosthetic cultures with phenotypically identical organisms. The presence of either is definitive for PJI.

Question 67

A patient undergoes a primary total hip arthroplasty via the direct anterior approach. Postoperatively, she reports numbness and dysesthesia over the anterolateral aspect of her thigh. Which nerve was most likely injured, and what is its anatomic course relative to the surgical interval?

Explanation

The lateral femoral cutaneous nerve is frequently injured during the direct anterior approach as it courses superficial to the sartorius muscle. The inter-nervous plane is between the tensor fascia latae (superior gluteal nerve) and the sartorius (femoral nerve).

Question 68

A 25-year-old male presents with deep groin pain exacerbated by hip flexion and internal rotation. Radiographs reveal an alpha angle of 70 degrees, consistent with a cam lesion. Which of the following best describes the pathophysiology of joint damage in this condition?

Explanation

Cam impingement is characterized by an aspherical femoral head that creates shear forces at the chondrolabral junction during flexion and internal rotation. This leads to outside-in delamination of the adjacent acetabular articular cartilage and labral tearing.

Question 69

A 68-year-old woman presents 3 weeks after an uncomplicated primary total hip arthroplasty (THA) with new-onset severe hip pain, erythema, and a draining sinus tract. Synovial fluid aspiration yields a white blood cell count of 45,000 cells/mcL with 92% neutrophils. Which of the following is the most appropriate surgical management?

Explanation

In the setting of an acute periprosthetic joint infection (symptoms less than 4 weeks post-surgery or acute hematogenous spread), DAIR with modular head/liner exchange is the preferred treatment. Two-stage exchange is reserved for chronic infections or cases where components are loose.

Question 70

During pre-operative templating for a total hip arthroplasty, the surgeon plans to use a high-offset femoral stem instead of a standard-offset stem. Assuming the leg length remains unchanged, what is the primary biomechanical effect of this decision?

Explanation

Increasing femoral offset lateralizes the greater trochanter, which increases the abductor moment arm. This restores soft-tissue tension, decreases the required abductor muscle force, and consequently decreases the overall joint reaction force.

Question 71

A 72-year-old man sustains a fall 4 years after a primary cementless THA. Radiographs reveal a spiral fracture around the tip of the femoral stem. The stem demonstrates gross subsidence, but the diaphyseal bone stock remains excellent. According to the Vancouver classification, what is the recommended treatment?

Explanation

This is a Vancouver B2 periprosthetic fracture (fracture around the stem, loose stem, good bone stock). The standard of care is revision arthroplasty bypassing the fracture site with a long, fluted, tapered cementless stem.

Question 72

A patient is scheduled for a THA. Preoperative standing and sitting lateral spinopelvic radiographs demonstrate a stiff lumbar spine with less than 10 degrees of pelvic tilt change between standing and sitting. How does this condition affect acetabular component positioning?

Explanation

A stiff spinopelvic junction prevents the normal posterior pelvic tilt required to accommodate hip flexion when sitting, increasing the risk of anterior impingement and posterior dislocation. The acetabular component typically requires higher anteversion and inclination to compensate for this stiffness.

Question 73

A 55-year-old male with a metal-on-metal THA presents with progressive groin pain and swelling. MRI with metal artifact reduction sequence (MARS) reveals a thick-walled cystic mass communicating with the joint. What is the most likely primary histologic characteristic of the periprosthetic tissue?

Explanation

Adverse local tissue reactions (ALTR) associated with metal-on-metal implants or trunnionosis are characterized histologically by ALVAL. This is a type IV delayed hypersensitivity response to metal ions.

Question 74

Which of the following manufacturing processes in highly cross-linked polyethylene (HXLPE) primarily contributes to the reduction of its mechanical yield strength and fatigue resistance compared to conventional polyethylene?

Explanation

While gamma irradiation creates cross-links that improve wear resistance, it leaves free radicals. Remelting eliminates these free radicals to prevent oxidation but decreases crystalline content, thereby reducing yield strength, ultimate tensile strength, and fatigue resistance.

Question 75

During a direct anterior approach for THA, the surgeon develops the superficial internervous plane. Between which two muscles is this superficial dissection performed?

Explanation

The superficial interval in the direct anterior (Smith-Petersen) approach is between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The deep interval is between the rectus femoris and gluteus medius.

Question 76

A 35-year-old active male presents with symptoms of femoroacetabular impingement. Radiographs demonstrate an alpha angle of 75 degrees and decreased femoral head-neck offset. In this patient's pathomorphology, what is the most common pattern of intra-articular damage?

Explanation

Cam impingement is characterized by a nonspherical femoral head squeezing into the acetabulum during flexion. This causes shear forces that lead to characteristic anterosuperior articular cartilage delamination and "inside-out" detachment of the labrum.

Question 77

A 45-year-old woman with a history of bilateral developmental dysplasia of the hip (Crowe type IV) is undergoing THA. Preoperative planning indicates the native femoral head is migrated 5 centimeters proximally. Which of the following surgical strategies is most appropriate to restore normal biomechanics while minimizing complications?

Explanation

In Crowe IV DDH, the acetabular component should be placed in the true paleopelvis to restore the anatomical center of rotation. A subtrochanteric shortening osteotomy is typically required to allow joint reduction without causing sciatic nerve stretch injury.

Question 78

A 50-year-old male presents with new-onset groin pain 3 years after a primary cementless THA. His pain is reproducible with active straight leg raise and resisted hip flexion. Radiographs show a well-fixed cup with 25 degrees of anteversion and 10 mm of anterior overhang. What is the most appropriate initial management?

Explanation

The clinical presentation is classic for iliopsoas impingement resulting from an overhanging anterior acetabular rim. Initial management should always be conservative, including physical therapy and image-guided injections, before considering surgical intervention like tenotomy or cup revision.

Question 79

A 66-year-old female presents with squeaking from her total hip arthroplasty placed 4 years ago. She has a ceramic-on-ceramic bearing. Which of the following factors is most strongly associated with the development of this complication?

Explanation

Squeaking in ceramic-on-ceramic THAs is heavily associated with edge loading, which disrupts the fluid lubrication film. Edge loading typically results from cup malposition, specifically high inclination or a mismatch in anteversion, leading to stripe wear on the ceramic head.

Question 80

A 70-year-old man requires a revision THA. Preoperative evaluation of the pelvis reveals severe bone loss with a complete dissociation of the superior and inferior halves of the hemipelvis. Which of the following constructs is most appropriate to achieve durable fixation in this scenario?

Explanation

The scenario describes a pelvic discontinuity. Achieving stability requires bridging the defect to unite the superior and inferior segments. This is best accomplished using highly porous metal augments with a cup-cage construct, a custom triflange, or a pelvic distraction technique.

Question 81

A 28-year-old patient on chronic corticosteroids develops symptomatic avascular necrosis (AVN) of the right femoral head. MRI reveals a subchondral crescent sign without joint space narrowing or acetabular changes. According to the Ficat and Arlet classification, what stage is this, and what is the best surgical option?

Explanation

The presence of a subchondral crescent sign indicates subchondral collapse, classifying this as Ficat Stage III AVN. Core decompression is generally ineffective at this stage, and THA is the most reliable procedure for pain relief and functional restoration.

Question 82

During a posterior approach to the hip, retractors are placed to expose the posterior column and acetabulum. The patient subsequently develops a dense foot drop postoperatively. Which portion of the affected nerve is most vulnerable to stretch injury in this location and why?

Explanation

The sciatic nerve is at risk during the posterior approach. The common peroneal division is more susceptible to stretch injury because it is located laterally, has fewer supportive connective tissue fascicles, and is anatomically tethered at the fibular head.

Question 83

A surgeon utilizes a collarless, polished, double-tapered cemented femoral stem (e.g., Exeter design) for a primary THA. What is the fundamental biomechanical principle by which this specific stem design achieves long-term stability?

Explanation

Polished, collarless, tapered stems operate on a force-closed or 'taper-slip' principle. The polished surface lacks bonding, allowing the stem to predictably subside into the cement mantle, converting axial loads into compressive radial forces against the cement and bone.

Question 84

A 58-year-old male complains of severe mechanical hip pain 6 months following a primary THA utilizing a dual mobility construct. Radiographs show eccentric seating of the inner cobalt-chromium head within the polyethylene liner. What complication has uniquely occurred in this specific implant design?

Explanation

Intra-prosthetic dislocation (IPD) is a complication unique to dual mobility bearings, where the inner metal head escapes the mobile polyethylene liner. It classically presents with eccentric positioning of the head on radiographs and requires revision.

Question 85

A 42-year-old male with a history of severe traumatic brain injury requires a THA for post-traumatic hip osteoarthritis. Radiographs preoperatively demonstrate massive heterotopic ossification (Brooker Class IV) bridging the joint. Following resection and THA, what is the most appropriate prophylaxis to prevent recurrence?

Explanation

Patients with prior severe heterotopic ossification, especially with neurogenic risk factors, are at very high risk for recurrence. Prophylaxis with single-dose localized radiation (given preop or within 72 hours postop) or oral NSAIDs (like Indomethacin) is the standard of care.

Question 86

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a 'major criterion' that definitively confirms the diagnosis of periprosthetic joint infection?

Explanation

The 2018 ICM criteria define two major criteria for definitive PJI: (1) a sinus tract communicating with the joint, or (2) two positive periprosthetic cultures of the exact same organism. Elevated inflammatory markers and alpha-defensin are minor criteria.

Question 87

A surgeon is evaluating a 70-year-old patient with an un-displaced subcapital femoral neck fracture. To maximize fracture stability and reduce the risk of nonunion and avascular necrosis during cannulated screw fixation, which mechanical configuration of the screws is optimal?

Explanation

For internal fixation of femoral neck fractures, three parallel screws in an inverted triangle configuration provide the most biomechanical stability. The inferior screw must sit adjacent to the dense bone of the calcar to resist inferior displacement and varus collapse.

Question 88

A 55-year-old female undergoes a THA using an anterolateral (Watson-Jones) approach. Postoperatively, she demonstrates a pronounced Trendelenburg lurch. Injury to which nerve is most directly responsible for this clinical finding?

Explanation

The superior gluteal nerve innervates the gluteus medius, gluteus minimus, and tensor fasciae latae. It is vulnerable during the anterolateral approach if dissection extends too far proximally (typically >5 cm from the greater trochanter), leading to abductor weakness and a Trendelenburg gait.

Question 89

A 55-year-old female presents with groin pain 5 years after a metal-on-metal total hip arthroplasty. Metal ion levels are elevated. MRI with MARS reveals a cystic mass communicating with the joint space. What is the most likely predominant histologic finding of the periarticular tissue?

Explanation

Adverse local tissue reactions (ALVAL) in metal-on-metal hips are characterized histologically by a perivascular lymphocytic infiltrate, macrophage accumulation, and tissue necrosis. Neutrophils suggest infection, while intracellular debris suggests standard polyethylene wear.

Question 90

A 65-year-old male presents with a chronically painful THA. Aspiration yields synovial fluid with a white blood cell count of 4,500 cells/uL and 85% polymorphonuclear neutrophils. According to the 2018 International Consensus Meeting criteria, which of the following biomarkers would most strongly support the diagnosis of a periprosthetic joint infection?

Explanation

Synovial fluid alpha-defensin is a major criterion and a highly specific biomarker for PJI in the 2018 ICM criteria. While ESR and D-dimer are useful screening tools, alpha-defensin has superior specificity and sensitivity for definitively confirming PJI.

Question 91

A direct anterior approach to the hip utilizes the internervous plane between the sartorius and the tensor fasciae latae (TFL). Proximal extension of this superficial dissection places which of the following nerves at greatest risk of injury?

Explanation

The lateral femoral cutaneous nerve (LFCN) is highly vulnerable during the superficial dissection of the direct anterior approach. It courses over the sartorius and can be injured with aggressive medial retraction or errant fascial incisions.

Question 92

A 72-year-old female presents with right thigh pain after a fall. She has a cementless right THA placed 10 years ago.

Assuming the radiograph shows a fracture around the tip of a loose femoral stem with poor proximal diaphyseal bone stock, what is the most appropriate surgical management?

Explanation

A fracture around a loose stem with poor bone stock is classified as a Vancouver B3 periprosthetic fracture. The standard of care is revision to a diaphyseal-engaging long stem (fluted, tapered, or fully porous-coated) to bypass the deficient proximal bone.

Question 93

A 24-year-old male hockey player presents with anterior groin pain exacerbated by hip flexion and internal rotation. Radiographs reveal a pistol-grip deformity and an alpha angle of 70 degrees. Which of the following best describes the pathomechanics of his condition?

Explanation

Cam impingement features an aspherical femoral head that forcefully enters the acetabulum during flexion. This creates outside-in shear forces that cause labral separation and adjacent chondral delamination from the acetabular rim.

Question 94

A 68-year-old man with a metal-on-polyethylene total hip arthroplasty presents with new-onset groin pain. Radiographs show a well-fixed construct. Blood cobalt levels are significantly higher than chromium levels. What is the most likely source of the wear debris?

Explanation

Elevated serum cobalt levels disproportionately higher than chromium in a metal-on-polyethylene bearing strongly suggests mechanically assisted crevice corrosion. This phenomenon, known as trunnionosis, occurs at the modular head-neck junction.

Question 95

A 52-year-old woman complains of an audible squeaking sound from her hip when walking up stairs, two years after receiving a ceramic-on-ceramic total hip arthroplasty. Which of the following factors is most strongly associated with this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading, often resulting from acetabular cup malposition (excessive anteversion or inclination). This disrupts fluid film lubrication, leading to stripe wear and audible noise.

Question 96

A 35-year-old patient with a history of high-dose corticosteroid use presents with severe groin pain. Radiographs show subchondral collapse (crescent sign) and early flattening of the femoral head, but the joint space is preserved. What is the most reliable definitive surgical treatment for pain relief and functional improvement?

Explanation

Once subchondral collapse (Ficat stage III) has occurred in femoral head osteonecrosis, joint-preserving procedures have unacceptably high failure rates. Total hip arthroplasty provides the most reliable pain relief and functional restoration in this setting.

Question 97

During a revision total hip arthroplasty, the surgeon suspects a complete separation of the superior and inferior halves of the hemipelvis. Which of the following radiographic signs preoperatively would most strongly confirm pelvic discontinuity?

Explanation

Pelvic discontinuity is a complete separation of the ilium from the ischium and pubis. Radiographic hallmarks include a visible transverse fracture line across the columns, medial translation of the inferior hemipelvis, and broken previously placed osteosynthesis plates.

Question 98

A 65-year-old male with a history of an L2-L5 spinal fusion undergoes preoperative planning for a THA. Standing and sitting lateral radiographs demonstrate less than 10 degrees of change in his pelvic tilt. How should the acetabular cup placement be modified to minimize the risk of posterior dislocation?

Explanation

Patients with stiff lumbar spines lack normal spinopelvic mobility and cannot dynamically alter pelvic tilt (posterior tilt) when sitting. To accommodate hip flexion and clear the anterior impingement limit, the acetabular component requires increased anteversion.

Question 99

When comparing highly cross-linked polyethylene (HXLPE) to conventional ultra-high-molecular-weight polyethylene (UHMWPE) for THA, the process of irradiation and subsequent remelting achieves which of the following mechanical property changes?

Explanation

Irradiation of polyethylene creates cross-links that significantly increase wear resistance. However, the subsequent remelting process used to extinguish free radicals alters the crystalline structure, reducing mechanical properties like fatigue strength.

Question 100

A 70-year-old female presents with an intractable Trendelenburg gait 3 years after a primary THA via a lateral approach. MRI confirms a massive, retracted, and fatty-infiltrated tear of the gluteus medius and minimus. What is the most appropriate surgical reconstruction option?

Explanation

In cases of chronic, massive abductor tears with severe fatty infiltration where primary repair is impossible, a gluteus maximus muscle transfer is a proven salvage procedure. It effectively restores active abduction and improves the Trendelenburg gait.

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

Orthopedic Hip 2026 MCQs: Board Review Questions & Answers (Part 1)

Key Takeaway

Orthopedic Hip 2026 MCQs: Board Review Questions & Answers (Part 1)

Chapter Index