ABOS Hip MCQs (Set 1): Anatomy, Trauma, Arthroplasty

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 1

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 2

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 3

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 4

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 5

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

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 9

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 10

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 11

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 12

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 13

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 14

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 15

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 16

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)?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 17

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 18

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 19

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 20

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 21

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 22

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 23

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?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 24

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

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

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 27

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)?

Hip 2001 Practice Questions: Set 1 (Solved) - Figure 28

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

During a direct anterior approach (Smith-Petersen) to the hip, an internervous plane is utilized. The superficial interval is developed between which of the following two muscles?

Explanation

The direct anterior approach exploits a true internervous plane. Superficial dissection is between the sartorius (femoral nerve) and tensor fasciae latae (superior gluteal nerve).

Question 27

A 28-year-old man sustains a vertically oriented (Pauwels Type III) femoral neck fracture. Biomechanically, which of the following internal fixation constructs provides the greatest stability against shear forces?

Explanation

Pauwels Type III fractures experience high shear forces. A sliding hip screw with an added derotational screw provides superior biomechanical stability against vertical shear compared to multiple cannulated screws.

Question 28

In total hip arthroplasty, successfully increasing the femoral offset without altering the leg length will have which of the following biomechanical effects?

Explanation

Increasing femoral offset lateralizes the femur, increasing the lever arm of the abductor muscles. This requires less abductor force to maintain a level pelvis, thereby decreasing the overall joint reaction force.

Question 29

A 45-year-old man presents with a posterior wall acetabular fracture associated with a posterior hip dislocation. CT imaging demonstrates a focal area of marginal impaction of the articular surface. During surgical fixation, what is the most appropriate management of the impacted segment?

Explanation

Marginal impaction indicates depression of the articular cartilage into the underlying cancellous bone. It must be elevated anatomically to restore joint congruity, and the resulting metaphyseal defect must be bone grafted prior to plating.

Question 30

Ceramic-on-ceramic bearings in total hip arthroplasty have excellent wear characteristics but are associated with a unique complication known as "squeaking". Which of the following is the most significant risk factor for this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic hips is primarily caused by disruption of fluid film lubrication. Component malposition (particularly cup anteversion/inclination errors) leading to edge loading is the most significant mechanical risk factor.

Question 31

According to the quadrant system described by Wasielewski for acetabular screw placement during THA, placing a screw into the anterior-superior quadrant places which of the following structures at greatest risk?

Explanation

The anterior-superior quadrant corresponds to the "death corona" where the external iliac artery and vein reside. Screws should generally be avoided in this quadrant to prevent catastrophic vascular injury.

Question 32

A 55-year-old patient is involved in a high-speed motor vehicle collision and sustains a subtrochanteric femur fracture. Predictable deformity of the proximal fragment is primarily caused by which combination of muscular forces?

Explanation

The proximal fragment in a subtrochanteric fracture is deformed by the iliopsoas (flexion), gluteus medius/minimus (abduction), and short external rotators (external rotation).

Question 33

A 62-year-old female presents 5 years after a metal-on-metal total hip arthroplasty with new-onset groin pain and a cystic mass. Histologic evaluation of the periprosthetic tissue is most likely to demonstrate which of the following?

Explanation

Adverse Local Tissue Reaction (ALTR) or Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion (ALVAL) in metal-on-metal hips represents a type IV hypersensitivity reaction. Histology characteristically shows perivascular lymphocytic infiltration.

Question 34

During a total hip arthroplasty via a posterior approach, the sciatic nerve is at risk of injury. Which specific division of the nerve is most susceptible to indirect injury (e.g., traction), and what is the anatomic reason?

Explanation

The peroneal division of the sciatic nerve is more commonly injured because it lies more laterally (closer to the retractors) and has larger fascicles with less protective connective tissue compared to the tibial division.

Question 35

Tranexamic acid (TXA) is widely utilized to reduce perioperative blood loss in joint arthroplasty. What is its precise mechanism of action?

Explanation

TXA is a synthetic analog of the amino acid lysine. It reversibly and competitively inhibits the activation of plasminogen to plasmin, thereby preventing the degradation of fibrin clots (antifibrinolytic effect).

Question 36

A 75-year-old woman presents with a reverse obliquity intertrochanteric femur fracture (AO/OTA 31-A3). If this injury is treated inappropriately with a sliding hip screw (dynamic hip screw), what is the most likely mode of biomechanical failure?

Explanation

A reverse obliquity fracture line lacks the lateral cortical buttress. Compression along a sliding hip screw leads to unopposed medial translation of the distal femoral shaft fragment, resulting in construct failure.

Question 37

In the manufacturing of highly cross-linked polyethylene (HXLPE) for use in total hip arthroplasty, what is the primary purpose of heating the polyethylene above its melting point (remelting) following irradiation?

Explanation

Irradiation causes cross-linking but also generates free radicals. Heating above the melting point (remelting) extinguishes these free radicals, preventing late oxidative degradation, though it slightly decreases the mechanical strength.

Question 38

Three months following an uncomplicated primary total hip arthroplasty, a patient complains that the operative leg feels longer. Clinical examination reveals equal tape measurements from the anterior superior iliac spine (ASIS) to the medial malleolus bilaterally. However, the distance from the umbilicus to the medial malleolus is greater on the operative side. What is the most appropriate initial management?

Explanation

Equal ASIS to medial malleolus measurements indicate equal true leg lengths. The discrepancy in umbilicus to malleolus measurements indicates an apparent leg length discrepancy, typically due to pelvic obliquity from muscle contracture. This generally resolves within 6 months with physical therapy.

Question 39

A 35-year-old male sustains a high-energy trauma resulting in a displaced femoral neck fracture.

The predominant blood supply to the adult femoral head, which is critically at risk in this injury, arises directly from which of the following vessels?

Explanation

The major blood supply to the adult femoral head comes from the lateral epiphyseal artery, which is the terminal continuation of the deep branch of the medial femoral circumflex artery (MFCA).

Question 40

A 24-year-old male arrives in the emergency department following a motorcycle collision. He is hypotensive and tachycardic. Pelvic radiographs demonstrate an anteroposterior compression (APC) type III pelvic ring injury. A pelvic binder is applied. For maximum mechanical effectiveness, the binder must be centered at the level of the:

Explanation

To optimally reduce pelvic volume and stabilize the fracture, a pelvic binder or sheet must be placed at the level of the greater trochanters. Placement higher over the iliac crests is less effective and can paradoxically open the pelvic floor.

Question 41

A cementless femoral stem design is chosen for a primary THA in a 60-year-old man. Compared to a fully porous-coated cylindrical stem, what is the primary biomechanical advantage of a proximally coated tapered wedge stem?

Explanation

Tapered wedge stems are designed to load the proximal femur more physiologically. Distally fixed, fully porous-coated, cylindrical stems are stiff and bypass the proximal femur, leading to significant proximal stress shielding and bone resorption.

Question 42

A 30-year-old active female sustains a posterior hip dislocation with an associated femoral head fracture that extends cephalad to the fovea capitis (Pipkin Type II). Following closed reduction of the hip joint, the displaced fracture is noted to have a 3mm step-off. What is the most appropriate definitive management?

Explanation

Pipkin II fractures involve the weight-bearing dome of the femoral head. In a young, active patient with a displaced fragment (step-off > 1-2 mm), open reduction and internal fixation is indicated to restore joint congruity and reduce post-traumatic arthritis.

Question 43

Trunnionosis has emerged as a significant mode of failure in modern total hip arthroplasty, particularly involving modular head-neck junctions. This process is most accurately described by which of the following mechanisms?

Explanation

Trunnionosis refers to the wear and corrosion at the modular head-neck taper interface. It is primarily driven by mechanically assisted crevice corrosion (MACC), which is a combination of fretting wear and subsequent electrochemical corrosion.

Question 44

A patient with advanced unilateral hip osteoarthritis is instructed to use a cane. To maximally reduce the joint reaction force on the affected hip, the cane should be held in the contralateral hand. What is the primary biomechanical reason for this reduction?

Explanation

Holding a cane in the contralateral hand provides an upward force at a long lever arm from the affected hip. This counter-torque dramatically reduces the amount of force the ipsilateral abductor muscles must generate, thereby decreasing the total joint reaction force.

Question 45

A 68-year-old female undergoes a revision total hip arthroplasty for aseptic loosening. Preoperative dual-energy x-ray absorptiometry (DEXA) scanning confirms severe osteoporosis. During impaction of a cementless acetabular component, a non-displaced medial wall acetabular fracture occurs. The component is stable. What is the most appropriate intraoperative management?

Explanation

For an intraoperative, non-displaced medial wall fracture where the cementless acetabular shell achieves rigid press-fit stability, the appropriate management is to leave the cup in place and supplement it with multiple screws to bypass the fracture and ensure fixation.

Question 46

Placement of a screw in the anterosuperior quadrant of the acetabulum (Wasielewski zones) during total hip arthroplasty places which of the following structures at greatest risk of injury?

Explanation

The anterosuperior quadrant is considered a danger zone due to the close proximity of the external iliac vessels. Safe screw placement is generally in the posterosuperior and posteroinferior quadrants.

Question 47

A 68-year-old female presents with acute thigh pain after a minor fall. Radiographs reveal a transverse subtrochanteric fracture with lateral cortical thickening and medial spiking. She has a 9-year history of alendronate use. What is the most appropriate surgical management?

Explanation

Atypical femur fractures associated with bisphosphonate use are best treated with full-length cephalomedullary nailing. Surgeons must be cautious of the increased lateral bow, which may require over-reaming or utilizing a nail with a smaller radius of curvature.

Question 48

A 70-year-old man with ankylosing spondylitis and a completely fused lumbar spine is undergoing a total hip arthroplasty. How does his stiff spinopelvic anatomy alter the typical acetabular component positioning to prevent posterior dislocation?

Explanation

A stiff lumbar spine prevents normal posterior pelvic tilt during sitting, maintaining the acetabulum in a relatively retroverted position. To avoid anterior impingement and posterior dislocation, the acetabular cup must be placed in greater anteversion.

Question 49

A 65-year-old man receives a ceramic-on-ceramic total hip arthroplasty. Two years later, he complains of a reproducible squeaking noise during gait. What is the most common biomechanical or radiographic finding associated with this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic bearings is strongly associated with edge loading, typically caused by component malposition (e.g., increased cup inclination or version mismatch). Edge loading disrupts fluid-film lubrication and leads to stripe wear.

Question 50

A 30-year-old man sustains a displaced, vertically oriented (Pauwels Type III) femoral neck fracture. Which of the following internal fixation constructs provides the most biomechanically stable fixation for this specific high-shear fracture pattern?

Explanation

Pauwels Type III fractures possess high vertical shear forces that lead to failure with standard multiple cancellous screws. A sliding hip screw (with a derotational screw) provides superior biomechanical stability against these sheer stresses.

Question 51

A 75-year-old woman sustains a periprosthetic femur fracture around a cemented polished taper-slip stem. Radiographs demonstrate a fracture near the tip of the stem with obvious cement mantle fragmentation and stem subsidence. What is the most appropriate classification and treatment?

Explanation

A fracture around a loose stem (Vancouver B2) mandates revision arthroplasty. The standard of care is revision to a long cementless extensively porous-coated or fluted tapered stem that bypasses the fracture by at least two cortical diameters.

Question 52

During an anterior (Smith-Petersen) approach to the hip for a periacetabular osteotomy, the surgeon develops the superficial internervous plane. Which of the following represents the correct muscles and their respective innervations for this interval?

Explanation

The superficial interval of the Smith-Petersen approach utilizes the true internervous plane between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve).

Question 53

A 60-year-old man with a metal-on-polyethylene total hip arthroplasty presents with new-onset groin pain and a palpable mass 5 years postoperatively. Blood work reveals elevated serum cobalt and chromium. Aspiration yields sterile, cloudy fluid. What is the most likely etiology?

Explanation

Elevated metal ions and an adverse local tissue reaction (ALTR) in a metal-on-polyethylene implant strongly suggest trunnionosis. This is caused by mechanically assisted crevice corrosion at the modular head-neck junction.

Question 54

A 25-year-old man involved in a motor vehicle collision presents with a shortened, internally rotated left lower extremity. Radiographs confirm a posterior hip dislocation without fracture. Which intervention is most critical for minimizing the risk of avascular necrosis (AVN) of the femoral head?

Explanation

The risk of AVN following a traumatic hip dislocation is directly correlated with the time to reduction. Closed reduction performed within 6 hours significantly lowers the incidence of AVN.

Question 55

Histologic evaluation of a successful, well-fixed porous-coated cementless titanium acetabular component retrieved 5 years postoperatively for an unrelated cause typically demonstrates bone ingrowth into approximately what percentage of the available porous surface?

Explanation

Although cementless components provide rigid biological fixation, histomorphometric studies of retrieved well-fixed porous implants show that actual bone ingrowth rarely exceeds 10% to 30% of the available porous surface.

Question 56

When treating a highly comminuted subtrochanteric femur fracture with an antegrade intramedullary nail, establishing a starting entry point that is too lateral to the tip of the greater trochanter typically leads to which of the following mechanical malalignments?

Explanation

A lateral starting point forces the intramedullary nail to deviate medially as it enters the canal. This medial vector pushes the proximal fragment into varus malalignment.

Question 57

A 60-year-old male is scheduled for a revision total hip arthroplasty. He has a history of severe Brooker class III heterotopic ossification following his index procedure. What is the most effective prophylactic regimen to prevent recurrence?

Explanation

Prophylaxis for severe heterotopic ossification includes either single-dose low-energy radiation (700-800 cGy) given pre- or postoperatively, or oral indomethacin for 2 to 6 weeks. A 3-day course of indomethacin is insufficient.

Question 58

During a posterior approach to the hip, excessive retraction or release of the short external rotators close to the intertrochanteric crest endangers the primary blood supply to the femoral head. These critical retinacular vessels are terminal branches of which artery?

Explanation

The deep branch of the medial circumflex femoral artery (MCFA) provides the primary blood supply to the adult femoral head via the posterosuperior retinacular vessels. It lies posterior to the obturator externus and anterior to the short external rotators.

Question 59

During an ilioinguinal approach for an anterior column acetabular fracture, significant arterial bleeding is encountered near the superior pubic ramus. This bleeding is most likely from the 'corona mortis', which is an anastomosis between the obturator vessels and which of the following?

Explanation

The corona mortis is a vascular anastomosis between the obturator and the external iliac or inferior epigastric systems. It crosses the superior pubic ramus and is highly susceptible to injury during the ilioinguinal approach to the pelvis.

Question 60

A 28-year-old man sustains a completely displaced, vertically oriented (Pauwels type III) femoral neck fracture. To maximize biomechanical stability and minimize the risk of shear-induced failure, which of the following fixation constructs is most appropriate?

Explanation

Pauwels type III fractures exhibit high shear forces due to their vertical orientation. A fixed-angle device, such as a sliding hip screw with a supplemental derotation screw, provides superior biomechanical stability against vertical shear compared to multiple cancellous screws.

Question 61

A 55-year-old active woman undergoes primary total hip arthroplasty with a ceramic-on-ceramic bearing. At her 2-year follow-up, she complains of a squeaking noise coming from the hip during deep flexion, though she is pain-free. What is the most significant risk factor for this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading of the bearing surfaces. This edge loading most commonly occurs due to component malposition, specifically excessive cup inclination (steep cup) or malversion.

Question 62

The direct anterior approach (DAA) to the hip is an internervous plane. Which of the following best describes the superficial neural interval used in this approach?

Explanation

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

Question 63

A 70-year-old woman sustains a reverse obliquity intertrochanteric hip fracture. Why is a cephalomedullary nail mechanically preferred over a sliding hip screw (SHS) for this specific fracture pattern?

Explanation

In reverse obliquity fractures, the lateral femoral cortex is disrupted, rendering a sliding hip screw biomechanically compromised as the shaft can translate medially. A cephalomedullary nail acts as an intramedullary buttress, preventing this medial displacement.

Question 64

Which of the following ligaments of the hip joint is the strongest and serves as the primary static restraint to hip extension?

Explanation

The iliofemoral ligament (Y ligament of Bigelow) is the strongest ligament in the body and is the primary restraint to hip extension and external rotation. It spans from the AIIS to the intertrochanteric line.

Question 65

A patient with severe spinopelvic stiffness secondary to ankylosing spondylitis is evaluated for a total hip arthroplasty. The patient's pelvis is fixed in a posterior pelvic tilt. How does this fixed deformity affect the functional orientation of the acetabulum when the patient transitions from sitting to standing?

Explanation

A posterior pelvic tilt increases the functional anteversion and inclination of the acetabulum. In patients with stiff spines unable to adapt, fixing the cup in standard anatomical version may lead to excessive functional anteversion, risking anterior dislocation in extension.

Question 66

A 64-year-old man presents with painful swelling in his groin three years after undergoing a metal-on-metal total hip arthroplasty. Blood work reveals significantly elevated serum cobalt and chromium ion levels. A MARS MRI demonstrates a large cystic pseudotumor. If revision surgery is undertaken, histologic evaluation of the periprosthetic tissue will most likely show:

Explanation

Metal-on-metal bearing failures often cause adverse local tissue reactions (ALTR) or ALVAL (Aseptic Lymphocyte-dominated Vasculitis-Associated Lesion). Histologically, this is characterized by a dense perivascular infiltrate of T-lymphocytes, distinct from the macrophage response seen in polyethylene wear.

Question 67

During surgical dislocation of the hip using the Ganz trochanteric flip approach for a femoral head fracture, the blood supply to the femoral head is protected by maintaining the integrity of which of the following structures?

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) is the primary blood supply to the femoral head. It runs closely to the obturator externus tendon, which must be protected during a surgical dislocation (Ganz approach) to prevent avascular necrosis.

Question 68

A 72-year-old female presents with a periprosthetic femur fracture around a cementless, proximally porous-coated femoral stem.

Radiographs reveal a fracture extending just distal to the tip of the stem. The stem is radiographically loose with subsidence, but the proximal bone stock is highly comminuted while the diaphyseal bone is intact. According to the Vancouver classification, what is the most appropriate management?

Explanation

This is a Vancouver B2 or B3 fracture (loose stem). Because the proximal bone is comminuted/inadequate and the stem is loose, the standard of care is to bypass the fracture and achieve distal fixation using a diaphyseal-engaging fluted tapered stem or extensively porous-coated stem.

Question 69

A 35-year-old man presents to the emergency department with a shortened, flexed, abducted, and externally rotated left lower extremity following a high-speed motorcycle accident. Which of the following is the most likely diagnosis?

Explanation

Anterior hip dislocations of the inferior (obturator) type classically present with the hip in flexion, abduction, and external rotation. Posterior dislocations typically present with the hip flexed, adducted, and internally rotated.

Question 70

During a primary total hip arthroplasty using a posterior approach, the surgeon decides to use a 'high offset' femoral stem instead of a standard offset stem. Assuming the neck angle remains the same, how does this stem primarily affect hip biomechanics?

Explanation

A high offset stem lateralizes the femoral shaft, which increases the abductor moment arm. This improves abductor efficiency and decreases the hip joint reaction force, without inadvertently lengthening the leg as a longer standard neck would.

Question 71

A 68-year-old man underwent a right total hip arthroplasty 5 years ago with a modular cobalt-chromium femoral head on a titanium stem. He now presents with persistent thigh pain. Inflammatory markers are normal, and joint aspiration is negative for infection. Radiographs show no loosening. Serum cobalt is disproportionately elevated compared to chromium. What is the most likely diagnosis?

Explanation

Trunnionosis is mechanically assisted crevice corrosion at the modular head-neck junction. It is characterized by elevated serum cobalt levels (often disproportionately higher than chromium) and local tissue reaction in the setting of mixed metal combinations (CoCr head on Ti stem).

Question 72

When advising a patient with severe left hip osteoarthritis on the use of a single-point cane, you instruct them to hold the cane in their right hand. What is the primary biomechanical rationale for this instruction?

Explanation

Using a cane in the contralateral hand provides a long lever arm that assists the ipsilateral hip abductors in maintaining a level pelvis. This significantly reduces the force the abductor muscles must generate, thereby profoundly decreasing the compressive joint reaction force across the hip.

Question 73

A 25-year-old male sustains a posterior wall acetabular fracture with a posterior hip dislocation. Post-reduction, he undergoes open reduction and internal fixation via a Kocher-Langenbeck approach. Postoperatively, he is noted to have an inability to extend his great toe and decreased sensation in the first dorsal web space. Which specific neural element was most likely injured?

Explanation

The common peroneal division of the sciatic nerve is anatomically more lateral and its fibers are more superficial/tethered, making it highly susceptible to injury from retractor placement or trauma during posterior hip dislocations and the Kocher-Langenbeck approach.

Question 74

In modern cementing techniques for total hip arthroplasty (third-generation cementing), vacuum mixing of the polymethylmethacrylate (PMMA) bone cement is standard practice. What is the primary biomechanical benefit of vacuum mixing?

Explanation

Vacuum mixing removes air bubbles from the PMMA during the mixing process, which significantly reduces the cement's macroporosity. This reduction in porosity eliminates stress risers, markedly increasing the fatigue life and tensile strength of the cement mantle.

Question 75

A patient is undergoing revision of a failed metal-on-metal total hip arthroplasty due to severe trunnionosis. The well-fixed titanium femoral stem will be retained, but the trunnion is macroscopically damaged. Which of the following head component combinations is most appropriate to place on the damaged trunnion?

Explanation

Placing a rigid ceramic head directly onto a damaged titanium trunnion can lead to catastrophic ceramic fracture due to point loading. The standard of care is to use a ceramic head equipped with a titanium adapter sleeve to securely interface with the deformed trunnion.

Question 76

A 45-year-old man presents with a Pipkin type II femoral head fracture associated with a posterior hip dislocation. The dislocation is successfully reduced in the emergency department, but the large fracture fragment remains displaced superior to the fovea capitis. What is the recommended surgical management?

Explanation

Pipkin type II fractures involve the weight-bearing portion of the femoral head (superior to the fovea). In a young, active patient, these require anatomic reduction and stable fixation (ORIF) to preserve the joint and minimize the risk of post-traumatic arthritis.

Question 77

An extensively porous-coated, cylindrically fully coated diaphyseal engaging stem is used in revision hip arthroplasty. To achieve predictable long-term biologic fixation (osseointegration), what is the minimum required distance of diaphyseal scratch fit?

Explanation

Extensively porous-coated cylindrical stems rely on initial mechanical stability in the diaphysis to allow for subsequent bone ingrowth. A rigid isthmic 'scratch fit' over a minimum distance of 4 to 6 cm is required to achieve this stability.

Question 78

Anatomical variation of the sciatic nerve as it exits the greater sciatic foramen is well documented. In approximately 10-15% of the population, a variant exists that can predispose to iatrogenic injury or piriformis syndrome. What is the most common anatomical variant of the sciatic nerve?

Explanation

The most common anatomical variation (present in roughly 10-15% of people) is the common peroneal division of the sciatic nerve piercing through the piriformis muscle, while the tibial division passes underneath it.

Question 79

A 60-year-old highly active man undergoes a primary total hip arthroplasty using a ceramic-on-ceramic bearing. Two years postoperatively, he complains of a reproducible, audible squeaking sound from the hip during deep flexion. Radiographs show a well-fixed implant but with a steeply positioned acetabular component. What is the most likely biomechanical cause of the squeaking?

Explanation

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading, typically caused by acetabular component malposition (e.g., steep inclination or excessive anteversion). Edge loading disrupts fluid film lubrication, resulting in stripe wear and acoustic emissions.

Question 80

During a direct anterior (Smith-Petersen) approach to the hip for total hip arthroplasty, the surgeon utilizes both superficial and deep internervous planes. Which of the following accurately describes the deep internervous plane for this approach?

Explanation

The direct anterior approach exploits the superficial internervous plane between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The deep plane lies between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve).

Question 81

A 75-year-old woman sustains a highly unstable intertrochanteric femur fracture and is treated with a cephalomedullary nail. To minimize the risk of lag screw cut-out, what is the maximum recommended tip-apex distance (TAD) as described by Baumgaertner?

Explanation

Baumgaertner et al. demonstrated that a tip-apex distance (TAD) of less than 25 mm significantly reduces the risk of lag screw cut-out in intertrochanteric fractures. The TAD is the sum of the distance from the tip of the screw to the apex of the femoral head on both AP and lateral radiographs.

Question 82

In the evaluation of a painful total hip arthroplasty, synovial fluid is aspirated and sent for an alpha-defensin test to rule out periprosthetic joint infection (PJI). Which of the following best describes the biologic function and source of alpha-defensin?

Explanation

Alpha-defensin is an antimicrobial peptide naturally released by activated human neutrophils in response to invading pathogens. It serves as a highly specific biomarker in synovial fluid for diagnosing periprosthetic joint infection.

Question 83

The widespread use of highly cross-linked polyethylene (HXLPE) in total hip arthroplasty has significantly reduced volumetric wear rates compared to conventional ultra-high-molecular-weight polyethylene. Which of the following biomechanical properties is typically DECREASED as a direct result of the high irradiation cross-linking process?

Explanation

While high irradiation increases cross-linking and dramatically improves wear resistance, it also alters the material's mechanical properties, notably decreasing its fatigue crack propagation resistance and overall ductility. Subsequent melting or annealing is required to eliminate free radicals and maintain oxidation resistance.

Question 84

To protect the deep branch of the medial femoral circumflex artery (MFCA) during a posterior approach to the hip, the surgeon should carefully avoid aggressive dissection and electrocautery at the upper border of which of the following muscles?

Explanation

The deep branch of the MFCA courses posteriorly between the lower border of the inferior gemellus and the upper border of the quadratus femoris. Protecting the superior aspect of the quadratus femoris prevents iatrogenic injury to the primary blood supply of the femoral head.

Question 85

A 58-year-old man presents with groin pain three years after a primary metal-on-polyethylene total hip arthroplasty. Aspiration yields fluid with elevated cobalt levels but normal chromium levels. MARS MRI demonstrates a solid pseudotumor. Which of the following implant design factors most significantly increases the risk of this specific complication?

Explanation

Mechanically assisted crevice corrosion (trunnionosis) at the head-neck junction is characterized by elevated cobalt relative to chromium. Risk factors include larger metal femoral heads, small trunnion tapers, and high off-set necks, which increase the mechanical lever arm and micromotion at the taper interface.

Question 86

A 32-year-old unrestrained driver is involved in a motor vehicle collision. Radiographs demonstrate a posterior hip dislocation associated with a femoral head fracture that involves the weight-bearing zone superior to the fovea capitis. According to the Pipkin classification, what is the grade of this injury?

Explanation

The Pipkin classification describes femoral head fractures associated with posterior hip dislocations. Type I is below the fovea, Type II is above the fovea (involving the weight-bearing surface), Type III involves an associated femoral neck fracture, and Type IV involves an associated acetabular fracture.

Question 87

An orthopedic surgeon is performing an anterior intrapelvic (modified Stoppa) approach for an acetabular fracture. The surgeon must identify and ligate the 'corona mortis' to prevent massive hemorrhage. This vascular structure is most commonly an anastomosis between which of the following systems?

Explanation

The corona mortis is a critical vascular anastomosis connecting the external iliac (or deep inferior epigastric) system and the internal iliac (obturator) system. It courses over the posterior aspect of the superior pubic ramus and is highly vulnerable during intrapelvic approaches.

Question 88

A 72-year-old osteoporotic woman is undergoing cemented total hip arthroplasty. The surgeon utilizes a highly polished, collarless, double-tapered (taper-slip) stem. Which of the following biomechanical principles is essential for the long-term success of this specific stem design?

Explanation

Force-closed or taper-slip cemented stems (e.g., Exeter) are highly polished and lack macroscopic locking features. They are explicitly designed to subside slightly within the cement mantle, functioning as a wedge that generates compressive hoop stresses, which bone cement is highly capable of tolerating.

Question 89

A 28-year-old man sustains a completely displaced, vertically oriented (Pauwels type III) femoral neck fracture. Which of the following fixation constructs provides the greatest biomechanical stability against vertical shear forces for this specific fracture pattern?

Explanation

Pauwels type III (vertical) femoral neck fractures experience extraordinarily high shear forces, leading to a high failure rate if treated with parallel cancellous screws alone. A fixed-angle device, such as a sliding hip screw, provides superior biomechanical resistance to vertical shear, while a supplemental screw prevents rotational displacement.

Question 90

During a primary total hip arthroplasty via a posterior approach, the surgeon utilizes the transverse acetabular ligament (TAL) as a soft-tissue landmark. Positioning the acetabular component parallel to the native TAL helps primarily determine which aspect of component orientation?

Explanation

The transverse acetabular ligament (TAL) spans the acetabular notch and serves as a reliable intraoperative landmark. Studies have shown that orienting the acetabular component parallel to the TAL establishes patient-specific anteversion, thereby minimizing the risk of postoperative dislocation.

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

AAOS/ABOS Hip MCQs (Set 1): Anatomy, Trauma & Arthroplasty | Board Prep

Key Takeaway

AAOS/ABOS Hip MCQs (Set 1): Anatomy, Trauma & Arthroplasty | Board Prep

Chapter Index