Hip Orthopedic MCQs (Set 3): Pathology & Trauma

Question 1

A patient who underwent a high tibial osteotomy (HTO) is now scheduled to undergo total knee arthroplasty (TKA). When compared with a patient undergoing primary TKA without a prior HTO, the patient should be advised to expect a higher incidence of

Explanation

Conversion TKA following a previous HTO can be successful; however, it is associated with poorer clinical results when compared with other primary TKAs. There is an increased likelihood of poor range of motion that is partially affected by patella infera created from the osteotomy. Patella infera also results in difficulty with surgical exposure. There has been no reported increase in the rate of infection, fracture, or loosening.

Question 2

Figures 22a and 22b show the radiographs of a patient who reports stiffness of the hip and associated pain. Management should consist of

Explanation

The patient has grade IV heterotopic ossification with the limb in an abnormal nonfunctional position. Treatment should consist of excision of the bone to restore hip motion and prophylaxis to prevent recurrent formation. The best time to excise the bone is controversial, with no conclusive evidence supporting early or late excision. Pellegrini VD Jr, Koniski AA, Gastel JA, Rubin P, Evarts CM: Prevention of heterotopic ossification with irradiation after total hip arthroplasty: Radiation therapy with a single dose of eight hundred centigray administered to a limited field. J Bone Joint Surg Am 1992;74:186-200.

Question 3

Figure 23 shows the radiograph of a 55-year-old man who underwent a total hip arthroplasty 5 years ago. Management should now consist of

Explanation

Because the radiograph shows that the femoral stem is loose within the femoral canal and there is a fracture in the distal cement mantle, the stem should be revised. The Ogden-type plate and the allograft bone plates will reconstruct the femur but will not restore stability to the stem. Similarly, traction may allow the femur to heal but will not restore stability to the femoral stem within the femur. Resection arthroplasty is considered a salvage option following failure of the other procedures. Lewallen DG, Berry DJ: Periprosthetic fracture of the femur after total hip arthroplasty: Treatment and results to date, in Cannon WD Jr (ed): Instructional Course Lectures 47. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 243-249.

Question 4

Compared with wear rates of metal-on-standard polyethylene bearings (75 to 250 um/y), the wear rate of metal-on-metal bearings for hip arthroplasty is approximately how many micrometers per year?

Explanation

Studies on older systems, as well as newer designs, have confirmed that metal-on-metal bearing surfaces undergo linear wear of 2 to 5 um per year. Ceramic bearing surfaces produced with recent technology perform even better, with a wear rate of 0.5 to 2.5 um per year. Clinical wear rates of metal-on-crosslinked polyethylene have not yet been determined. McKellop H, Park SH, Chiesa R, et al: In vivo wear of three types of metal on metal hip prostheses during two decades of use. Clin Orthop 1996;329:S128-S140.

Question 5

A follow-up examination of a patient 6 weeks after knee surgery reveals a range of motion from 5 degrees to 55 degrees of flexion. Which of the following statements best summarizes the role of manipulation under anesthesia for this patient?

Explanation

Esler and associates evaluated the use of manipulation under anesthesia in 47 knees. Manipulation was considered when intensive physical therapy failed to increase flexion to more than 80 degrees. The mean time from arthroplasty to manipulation was 11.3 weeks, and the mean active flexion before manipulation was 62 degrees. One year later, the mean gain was 33 degrees. Definite sustained gains in flexion were achieved even when manipulation was performed 4 or more months after arthroplasty. An additional 21 patients who met the criteria for manipulation declined the procedure, and despite continued physical therapy, they showed no significant increase in knee flexion.

Question 6

The most compelling clinical reason to convert a hip arthrodesis to a total hip arthroplasty is that the latter

Explanation

Studies show that degenerative arthritis of the spine associated with a hip arthrodesis can be decreased with conversion to a total hip arthroplasty. The pain associated with degenerative arthritis of the knee usually persists after arthrodesis take-down procedures, and often requires total knee arthroplasty. Pain in the contralateral hip is not resolved by converting the arthrodesis. Improving range of motion of the hip and correcting a limb-length discrepancy are not good indications for take-down procedures. Strathy GM, Fitzgerald RH Jr: Total hip arthroplasty in the ankylosed hip: A ten-year follow-up. J Bone Joint Surg Am 1988;70:963-966.

Question 7

A 60-year-old woman reports a painful hip arthroplasty after undergoing surgery 18 months ago. Radiographs show stable cementless implants without signs of ingrowth. Laboratory studies show an erythrocyte sedimentation rate of 50 mm/h. Management should now consist of

Explanation

Significant elevation of the erythrocyte sedimentation rate in a patient with a painful hip arthroplasty mandates a complete work-up for infection prior to considering revision surgery. Reproducibility and reliability of ultrasonography as a diagnostic test still needs clarification. Aspiration is the easiest and most cost-effective test and should be performed prior to nuclear imaging. The latter is most valuable if the results are negative, strongly predicting the absence of infection. Barrack RL, Harris WH: The value of aspiration of the hip joint before revision total hip arthroplasty. J Bone Joint Surg Am 1993;75:66-76.

Question 8

Femoral osteotomy for dysplasia of the hip will most likely result in

Explanation

Patients should expect pain relief after femoral osteotomy for hip dysplasia. Patients should not expect improved motion or abduction strength and should be counseled about a postoperative limp and unequal limb lengths. Pellicci PM, Hu S, Garvin KL, Salvati EA, Wilson PD Jr: Varus rotational femoral osteotomies in adults with hip dysplasia. Clin Orthop 1991;272:162-166.

Question 9

Figure 24 shows the radiograph of an otherwise healthy 56-year-old patient who reports hip pain after undergoing a primary cementless hip replacement 4 months ago. The next most appropriate step should consist of

Explanation

Periosteal new bone formation is a warning sign of prosthetic infection. Indomethacin may prevent heterotopic ossification if given early enough; however, it is irrelevant in this patient. A C-reactive protein and a sed rate are useful screening studies that add to the predictive value of the radiographs and may be performed routinely if sepsis is suspected. A bone scan obtained 4 months after surgery would show increased uptake in all cases. If results of a sed rate and C-reactive protein are normal, then a biopsy should be considered to rule out a neoplasm.

Question 10

Which of the following is considered a physiologic effect of anemia?

Explanation

The expected physiologic effects of anemia include an increased heart rate and increased cardiac output. The coronary blood flow requirement increases. There is a decrease in peripheral resistance and blood viscosity.

Question 11

A patient with severe rheumatoid arthritis reports progressive hip pain. Serial hip radiographs will most likely show which of the following findings?

Explanation

Radiographic findings in patients with rheumatoid arthritis include symmetric joint space narrowing, periacetabular and femoral head erosions, and diffuse periarticular osteopenia. In advanced stages, protrusio acetabuli is a common finding. Ranawat and associates have shown a rate of superior femoral head migration of 4.5 mm per year and medial (axial) migration of 2.5 mm per year. Asymmetric joint space narrowing is a classic radiographic finding of degenerative arthrosis. Sacroiliac joint ankylosis commonly occurs in ankylosing spondylitis. Hip synovitis is a pathologic diagnosis, not a radiographic finding. Lachiewicz PF: Rheumatoid arthritis of the hip. J Am Acad Orthop Surg 1997;5:332-338.

Question 12

A 70-year-old woman reports anterior knee pain after undergoing an uncomplicated total knee arthroplasty 6 months ago. Examination reveals prepatellar tenderness, with no extensor lag. The radiographs shown in Figures 25a through 25c reveal a well-fixed patellar component. Management should consist of

Explanation

Patellar fractures that occur after a total knee arthroplasty are usually stress fractures. Integrity of the extensor mechanism precludes the need for surgical repair or internal fixation, while stability and fixation of the patellar component determine whether revision is indicated. A cylindrical cast and full weight bearing for 6 weeks is recommended for transverse fractures with an intact extensor mechanism and a stable component. A similar fracture, if vertical, may be treated with earlier motion. Rorabeck CH, Angliss RD, Lewis PL: Fractures of the femur, tibia, and patella after total knee arthroplasty: Decision making and principles of management, in Cannon WD Jr (ed): Instructional Course Lectures 47. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 449-458. Hozack WJ, Goll SR, Lotke PA, Rothman RH, Booth RE Jr: The treatment of patellar fractures after total knee arthroplasty. Clin Orthop 1988;236:123-127.

Question 13

Figure 26 shows the MRI scan of a 60-year-old man who has had groin pain for the past 2 months. The patient reports pain with ambulation, and examination reveals an antalgic gait. He denies any history of steroid or alcohol abuse. Plain radiographs are normal. Management should include

Explanation

The patient has transient osteoporosis of the hip. Transient osteoporosis is usually a self-limited condition that is most frequently seen in women in the third trimester of pregnancy and in men in the sixth decade of life. Transient osteoporosis is best treated with protected weight bearing.

Question 14

Which of the following is considered the most common complication of the impaction grafting technique for femoral revision surgery?

Explanation

Impaction grafting technique for femoral revision surgery has become increasingly popular over the past decade. This technique is designed to address cavitary deficiencies of the femur. The femoral stem is inserted with cement fixation. Its clinical efficacy has not been shown to be superior to extensively porous-coated stems. Early subsidence of the stem has been reported in more than 50% of the patients. However, loss of fixation has occurred infrequently (5%) in reported series conducted by experienced surgeons. It has not been shown to have a higher infection rate. Gie GA, Linder L, Ling RS, Simon JP, Slooff TH, Timperley AJ: Impacted cancellous allografts and cement for revision total hip arthroplasty. J Bone Joint Surg Br 1993;75:14-21.

Question 15

What is the most likely late complication associated with cementless total knee replacement?

Explanation

In cementless total knee replacement, the risk of osteolysis is 30% if both components are placed without cement and screws are used for tibial fixation. The risk is 10% when a cemented tibial component is used, and the risk is 0% when both components are cemented. Loss of motion, patellofemoral pain, heterotopic bone formation, and patellar clunk are complications that can occur after cemented or cementless components are placed.

Question 16

Figure 27 shows the radiograph of a 68-year-old woman with a history of rheumatoid arthritis who was injured in a fall. History reveals that she has been asymptomatic since undergoing a left total knee arthroplasty 9 years ago. Management should consist of

Explanation

A supracondylar fracture of the femur that occurs after total knee replacement can be treated effectively by a number of methods. For this fracture, the use of a retrograde supracondylar nail has been found to be effective in several series. The treatment of these complex injuries needs to be individualized based on the stability of the implant, the quality of the bone, and the extent of comminution of the fracture. Revision with the use of an unstemmed implant will not result in effective stabilization of the knee or the fracture.

Question 17

Design factors that enhance the long-term survival of proximally coated cementless hip implants include both initial stability and

Explanation

Proximally coated femoral components were conceived in response to the proximal stress shielding seen with extensively coated total hip stems, but initial patient studies showed problems with osteolysis, thigh pain, and stability. However, Mont and Hungerford now report that second-generation devices that have been in use more than 5 years clinically have shown very low aseptic loosening rates (1% to 3%), and patients report less thigh pain (less than 5% in most studies). These results can be attributed to improved geometry, instruments, and technique, which ensure initial implant stability. The authors suggest that proximal coating must be circumferential to seal the diaphysis from wear debris, and they note that the concept of proximal coating for cementless femoral stems seems viable as long as the twin requirements of circumferential coating and rigid initial stability are realized. Mont MA, Hungerford DS: Proximally coated ingrowth prostheses: A review. Clin Orthop 1997;344:139-149. Engh CA, Hooten JP Jr, Zettl-Schaffer KF, Ghaffarpour M, McGovern TF, Bobyn JD: Evaluation of bone ingrowth in proximally and extensively porous-coated anatomic medullary locking prostheses retrieved at autopsy. J Bone Joint Surg Am 1995;77:903-910.

Question 18

A 45-year-old man with a painful varus knee is being considered for an upper tibial osteotomy. Which of the following factors is considered the most compelling argument against this procedure?

Explanation

Proximal tibial osteotomy is appropriate for the younger and/or athletic patient who has mild to moderate medial compartment osteoarthritis. Relative contraindications include limited range of motion (eg, flexion contracture of 15 degrees), anatomic varus of greater than 10 degrees, advanced patellofemoral arthritis, and tibial subluxation. Inflammatory arthritides involve all the compartments and are a contraindication to osteotomies around the knee.

Question 19

An obese patient undergoing total knee arthroplasty is at increased risk for which of the following complications?

Explanation

The rate of wound complications is significantly increased after total knee arthroplasty in obese patients. Knee scores and the rate of aseptic loosening or patellar subluxation do not appear to be significantly altered. Winiarsky R, Barth P, Lotke P: Total knee arthroplasty in morbidly obese patients. J Bone Joint Surg Am 1998;80:1770-1774. Stern SH, Insall JN: Total knee arthroplasty in obese patients. J Bone Joint Surg Am 1990;72:1400-1404.

Question 20

Figures 28a and 28b show the radiographs of a 79-year-old man who has constant knee pain. Prior to performing elective knee replacement surgery, management should include

Explanation

The radiographs show established Paget's disease. Bony expansion is evident, with thickened trabeculae consistent with the disordered bone remodeling process. A reduction of the serum alkaline phosphatase level to 50% of the pretreatment level may reduce pain from Paget's disease, and it is recommended prior to consideration of joint replacement. In elective cases, treatment of Paget's disease should begin at least 6 weeks prior to surgery. The other modalities are not related to the treatment of Paget's disease. Kaplan FS, Singer FS: Paget's disease of bone: Pathophysiology, diagnosis, and management. J Am Acad Orthop Surg 1995;3:336-344. Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 129-184.

Question 21

What is the most common complication of using structural bulk allograft to reconstruct segmental defects of the acetabulum?

Explanation

Both autograft and allograft have been used for complex acetabular reconstructions. They have been shown to be successful in the short term. However, graft resorption with collapse and subsequent cup loosening have occurred at high rates for both types of grafts, especially if reinforcement rings or cages are not used. Jasty M, Harris WH: Salvage total hip reconstruction in patients with major acetabular bone deficiency using structural femoral head allografts. J Bone Joint Surg Br 1990;72:63-67. Paprosky WG, Magnus RE: Principles of bone grafting in revision total hip arthroplasty: Acetabular technique. Clin Orthop 1994;298:147-155.

Question 22

Radiographs of a 12-year-old boy who has knee pain show a 2-cm osteochondral lesion of the lateral aspect of the medial femoral condyle. The fragments are not detached from the femur. Initial management should consist of

Explanation

For a pediatric patient without mechanical symptoms, initial management of an osteochondral defect lesion that is not detached should consist of casting in flexion. Failure to respond to several weeks or months of nonsurgical management may warrant surgical treatment.

Question 23

Which of the following drawbacks is associated with the Ganz periacetabular osteotomy?

Explanation

Although technically challenging, the Ganz periacetabular osteotomy offers advantages over other rotational pelvic osteotomies. Posterior column integrity is maintained, as is the acetabular vascular supply. Free mobility of the fragment makes large corrections in the center edge angle possible. Because of the asymmetric cuts and the need to restore anterior coverage, there is a tendency to anterior displacement of the joint while flexing the acetabulum. The procedure is commonly performed through a Smith-Petersen incision. Trousdale RT, Ganz R: Periacetabular osteotomy, in Callaghan JJ, Rosenberg AG, Rubash HE (eds): The Adult Hip. Philadelphia, Pa, Lippincott-Raven, 1998, pp 789-802. 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 24

Which of the following lesions is best suited for autologous chondrocyte implantation?

Explanation

Articular chondrocyte implantation is best performed for focal chondral defects of one area of the joint. It is not indicated for osteoarthritis. Mandelbaum BR, Brown JE, Fu F, et al: Articular cartilage lesions of the knee. Am J Sports Med 1998;26:853-861. Minas T, Nehrer S: Current concepts in the treatment of articular cartilage defects. Orthopedics 1997;20:525-538.

Question 25

The additional risk of complications in organ transplant patients receiving a total joint arthroplasty is attributed to

Explanation

Tannenbaum and associates found that patients who had a joint replacement after an organ transplantation had a rate of infection of 19% (five of 27 joint replacements in 16 patients). They retrospectively reviewed the results of 35 joint (hip or knee) replacements in 19 patients who had an organ transplant. The patients received a standard immunosuppressive induction regimen at the time of the transplantation and were maintained on a combination of prednisone, azathioprine, and cyclosporin A. All patients received antibiotics perioperatively, but antibiotic-impregnated bone cement was not used for any procedure. Six joint replacements in three patients (median patient age of 48.2 years at the time of the arthroplasty) were performed before a renal transplantation. Twenty-four joint replacements in 14 patients (average patient age of 40.9 years at the time of the arthroplasty) were performed after an organ transplantation. Two patients, with an average age of 53.8 years at the time of the arthroplasty, each had a joint replacement both before and after a liver transplantation (a total of five joint replacements). The average duration of follow-up after the first joint replacement was 8.8 years (range, 1 to 23 years). An infection developed around the implant in five patients who had undergone the joint replacement after a transplantation. The average interval from implantation of the prosthesis until detection of the infection was 3.4 years (range, 1 to 6 years). Of two patients who underwent a liver transplant, one had Pseudomonas aeruginosa infection and the other Escherichia coli infection. Of three patients who underwent a renal transplantation, one was infected with Staphylococcus epidermidis, one with Enterococcus, and one with Serratia marcescens.

Question 26

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head. During a posterior approach to the hip, protecting this artery is critical. Which of the following anatomic landmarks best identifies the location of the deep branch of the MFCA?

Explanation

The deep branch of the MFCA courses posteriorly between the pectineus and iliopsoas, then runs between the obturator externus and quadratus femoris. Protecting the obturator externus tendon during posterior hip surgery protects this crucial vessel.

Question 27

A 25-year-old unrestrained driver is involved in a high-speed motor vehicle collision and presents with a posterior hip dislocation. Upon physical examination in the emergency department, what is the classic resting position of the affected lower extremity?

Explanation

Posterior hip dislocations typically present with the affected limb shortened, flexed, adducted, and internally rotated. In contrast, anterior hip dislocations often present with the hip flexed, abducted, and externally rotated.

Question 28

During an anterior ilioinguinal approach for an acetabular fracture, the surgeon must identify and ligate the corona mortis to prevent life-threatening hemorrhage. The corona mortis represents an anastomosis between which two vascular systems?

Explanation

The corona mortis is a critical vascular anastomosis connecting the external iliac or inferior epigastric system with the obturator system. It is found on the posterior aspect of the superior pubic rami and must be carefully managed during anterior pelvic approaches.

Question 29

A healthy 32-year-old male sustains a displaced intracapsular femoral neck fracture after falling from a height.

What is the most appropriate definitive management for this patient?

Explanation

In physiologically young and active patients, a displaced femoral neck fracture is considered a surgical urgency to preserve the native hip joint. Urgent anatomic reduction and stable internal fixation minimize the risk of avascular necrosis and nonunion.

Question 30

The Smith-Petersen approach to the hip utilizes a true internervous plane. Which of the following accurately describes the muscular and neurologic intervals for the superficial dissection?

Explanation

The superficial interval of the Smith-Petersen (anterior) approach is between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve).

Question 31

A 38-year-old female presents with persistent groin pain exacerbated by hip flexion. Radiographs demonstrate a crossover sign on the AP pelvis view. This radiographic finding is most strongly associated with which of the following pathologies?

Explanation

The crossover sign on an AP pelvis radiograph indicates cranial retroversion of the acetabulum, where the anterior wall crosses over the posterior wall. This is a classic hallmark of pincer-type femoroacetabular impingement (FAI).

Question 32

A 40-year-old male with a history of corticosteroid use presents with bilateral hip pain.

Imaging confirms Ficat Stage II avascular necrosis of the femoral head with no evidence of subchondral collapse. Which of the following is the most appropriate initial surgical intervention?

Explanation

Ficat Stage II avascular necrosis involves cystic and sclerotic changes without subchondral collapse. Core decompression is indicated to reduce intraosseous pressure and promote revascularization before structural failure occurs.

Question 33

In a highly comminuted subtrochanteric femur fracture, the proximal fragment typically assumes a predictable deformed position due to un-opposed muscular forces. What is the classic position of this proximal fragment?

Explanation

The proximal fragment in a subtrochanteric fracture is flexed by the iliopsoas, abducted by the gluteus medius and minimus, and externally rotated by the short external rotators.

Question 34

During a total hip arthroplasty, the surgeon is inserting screws for supplemental acetabular shell fixation. According to the quadrant system described by Wasielewski, which quadrant represents the 'safe zone' to minimize risk of neurovascular injury?

Explanation

The posterosuperior quadrant is considered the safe zone for acetabular screw placement. The posteroinferior quadrant risks the sciatic nerve and internal pudendal vessels, while the anterior quadrants risk the external iliac and obturator vessels.

Question 35

Which of the following vessels is the primary contributor to the blood supply of the adult femoral head?

Explanation

The profound blood supply to the adult femoral head is predominantly provided by the deep branch of the medial femoral circumflex artery (MFCA). Injury to this vessel dramatically increases the risk of avascular necrosis.

Question 36

A patient with a posterior hip dislocation subsequently develops a sciatic nerve palsy. Which component of the sciatic nerve is most frequently and severely injured in this scenario, and what is the primary clinical manifestation?

Explanation

The peroneal (fibular) division of the sciatic nerve is larger, more tethered, and situated laterally, making it highly susceptible to stretch injury during a posterior hip dislocation. This presents clinically as foot drop and weakness in ankle dorsiflexion.

Question 37

When evaluating an intertrochanteric femur fracture for stability and implant choice, which of the following characteristics most strongly indicates the need for an intramedullary nail over a sliding hip screw?

Explanation

A lateral wall thickness of less than 20.5 mm in an intertrochanteric fracture is a major predictor of postoperative lateral wall fracture and subsequent failure if treated with a sliding hip screw. Intramedullary nailing is indicated for these unstable patterns.

Question 38

A 28-year-old male presents with groin pain and decreased internal rotation of the hip. He has a history of a slipped capital femoral epiphysis (SCFE) treated with in situ pinning during adolescence. This patient is at highest risk for developing which of the following conditions?

Explanation

In situ pinning of a SCFE often leaves a residual prominent anterior head-neck junction. This decreased offset frequently leads to Cam-type femoroacetabular impingement in early adulthood.

Question 39

On a Judet obturator oblique radiograph of the pelvis, the 'spur sign' is a pathognomonic finding for which specific type of acetabular fracture?

Explanation

The spur sign, seen on the obturator oblique radiograph, represents the intact portion of the ilium protruding superior to the displaced acetabular columns. It is the hallmark radiographic feature of a both-column acetabular fracture.

Question 40

A 55-year-old female presents with chronic lateral hip pain that is refractory to conservative management. Physical examination reveals a positive Trendelenburg sign and weakness with resisted hip abduction. MRI is most likely to show pathology involving which structure?

Explanation

Refractory lateral hip pain accompanied by abductor weakness and a positive Trendelenburg sign is classic for greater trochanteric pain syndrome involving tears or severe tendinopathy of the gluteus medius and/or minimus tendons.

Question 41

During a direct anterior approach for total hip arthroplasty, the lateral femoral cutaneous nerve is at risk. To minimize injury, the surgeon should remember that the nerve typically courses:

Explanation

The lateral femoral cutaneous nerve typically enters the thigh by passing under the inguinal ligament just medial to the anterior superior iliac spine (ASIS). Incisions should avoid traveling too medially to protect this nerve.

Question 42

A Pauwels type III femoral neck fracture is characterized by a high angle relative to the horizontal plane. Why do these fractures have a significantly higher rate of nonunion compared to Pauwels type I fractures?

Explanation

Pauwels type III fractures are highly vertical (angle > 50 degrees). This orientation converts joint reactive forces into substantial shear forces across the fracture site, drastically increasing the risk of fixation failure and nonunion.

Question 43

When utilizing the ilioinguinal approach for an anterior acetabular fracture, three 'windows' are developed. The middle window provides access to the pelvic brim. What structures define the medial and lateral borders of this middle window?

Explanation

In the ilioinguinal approach, the middle window is formed between the iliopsoas muscle/iliopectineal fascia laterally and the external iliac vessels medially. It allows excellent access to the pelvic brim and quadrilateral plate.

Question 44

A surgeon is performing a Kocher-Langenbeck approach for a posterior wall acetabular fracture. Which combination of intraoperative limb positioning is most effective for protecting the sciatic nerve from stretch injury during retraction?

Explanation

The sciatic nerve courses posterior to the hip and crosses the posterior knee. Extending the hip and flexing the knee puts the nerve on maximum slack, thereby minimizing the risk of iatrogenic traction injury during the posterior approach.

Question 45

A patient presents with a traumatic hip dislocation and is diagnosed with a Pipkin type IV fracture.

By definition, this injury includes a fracture of the femoral head combined with which of the following?

Explanation

The Pipkin classification describes femoral head fractures associated with hip dislocations. A Pipkin type IV fracture is defined as a femoral head fracture combined with an associated fracture of the acetabular rim.

Question 46

A 45-year-old male with a history of alcohol abuse presents with severe groin pain. AP pelvis and frog-leg lateral radiographs reveal a 'crescent sign' in the anterosuperior aspect of the femoral head. According to the Ficat classification, what does this sign represent?

Explanation

The 'crescent sign' represents a subchondral fracture signaling impending or early structural collapse of the femoral head. In the Ficat system, this subchondral collapse characterizes Stage III avascular necrosis.

Question 47

During a posterior approach to the hip, protecting the medial circumflex femoral artery (MFCA) is critical. The main branch of the MFCA typically courses posterior to the obturator externus tendon and anterior to which of the following muscles?

Explanation

The MFCA provides the primary blood supply to the femoral head. Its main branch courses anterior to the quadratus femoris and posterior to the obturator externus.

Question 48

A 65-year-old man presents with groin pain 15 years after an uncemented total hip arthroplasty.

Radiographs show extensive expansile radiolucencies around the acetabulum. Which of the following is the primary cell type responsible for initiating the bone resorption seen in this condition?

Explanation

Polyethylene wear particles are phagocytosed by macrophages, initiating an inflammatory cascade. These macrophages release cytokines (TNF-alpha, IL-1, IL-6) that stimulate osteoclastic bone resorption, leading to osteolysis.

Question 49

A 35-year-old man sustains a vertically oriented femoral neck fracture (Pauwels type III). Biomechanical studies suggest that which of the following fixation constructs provides the highest resistance to shear forces for this fracture pattern?

Explanation

Pauwels type III fractures are highly unstable and subjected to significant shear forces. A sliding hip screw (fixed-angle device) combined with a derotational screw provides superior biomechanical stability compared to multiple parallel cancellous screws.

Question 50

A surgeon is performing a direct lateral (Hardinge) approach to the hip. To avoid injury to the superior gluteal nerve, the proximal split in the gluteus medius should not extend beyond what distance from the tip of the greater trochanter?

Explanation

The superior gluteal nerve innervates the gluteus medius, minimus, and tensor fasciae latae. To prevent denervation of the anterior portion of the abductors, the split should not extend more than 5 cm proximal to the greater trochanter.

Question 51

A 28-year-old hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate an alpha angle of 70 degrees. This radiographic finding is most consistent with which of the following?

Explanation

An alpha angle greater than 50-55 degrees indicates a loss of the normal femoral head-neck offset, characteristic of Cam impingement. Pincer impingement is associated with acetabular overcoverage, such as retroversion or coxa profunda.

Question 52

A 42-year-old woman with a history of systemic lupus erythematosus presents with progressive hip pain.

An MRI confirms early-stage avascular necrosis (Ficat Stage II) with no subchondral collapse. What is the most appropriate initial surgical intervention?

Explanation

Core decompression is indicated for symptomatic, pre-collapse avascular necrosis of the femoral head (Ficat Stage I and II). Once subchondral collapse occurs (Ficat Stage III), total hip arthroplasty is generally required.

Question 53

In a subtrochanteric femur fracture, the proximal fragment is typically deformed into flexion, abduction, and external rotation. Which muscle group is primarily responsible for the external rotation deformity?

Explanation

The short external rotators (piriformis, gemelli, obturator internus) pull the proximal fragment into external rotation. The iliopsoas flexes the fragment, while the gluteus medius and minimus abduct it.

Question 54

A 55-year-old man who underwent a metal-on-metal total hip arthroplasty 8 years ago presents with new-onset groin pain and a palpable mass. Aspiration yields sterile, cloudy fluid. What is the most likely pathological mechanism?

Explanation

Adverse local tissue reactions (ALTR) or pseudotumors in metal-on-metal hips are primarily driven by a Type IV delayed hypersensitivity reaction to metal ions (cobalt and chromium). This leads to aseptic lymphocytic vasculitis-associated lesions (ALVAL).

Question 55

A 30-year-old man is involved in a motor vehicle collision and sustains a pelvic injury.

Imaging reveals an acetabular fracture. The 'spur sign' on an obturator oblique plain radiograph is pathognomonic for which fracture pattern?

Explanation

The 'spur sign' represents the intact portion of the ilium that remains attached to the axial skeleton while the articular acetabulum is completely dissociated. It is pathognomonic for a both-column acetabular fracture.

Question 56

A patient is scheduled for surgical excision of heterotopic ossification (HO) following previous acetabular trauma. To prevent recurrence, postoperative prophylaxis is planned. Which of the following is the most standard prophylactic regimen?

Explanation

Prophylaxis against heterotopic ossification typically consists of either a single fraction of external beam radiation (700-800 cGy) given postoperatively or oral indomethacin for 2 to 6 weeks. Bisphosphonates delay mineralization but do not prevent the osteoid formation.

Question 57

A 25-year-old unrestrained driver sustains a dashboard injury during a collision. He presents with his right hip flexed, adducted, and internally rotated. Neurological examination reveals weak ankle dorsiflexion and decreased sensation over the dorsal foot. Which nerve division is most likely injured?

Explanation

The presentation describes a posterior hip dislocation, which most commonly injures the sciatic nerve. The peroneal division is more susceptible to stretch injury than the tibial division because it is tethered at the fibular head and sits more laterally.

Question 58

During an anterior intrapelvic (modified Stoppa) approach to the acetabulum, the surgeon must identify and ligate the 'corona mortis'. This structure represents an anastomosis between which two vascular systems?

Explanation

The corona mortis is a highly variable vascular anastomosis between the external iliac (or inferior epigastric) and the obturator (branch of internal iliac) vessels. It crosses the superior pubic ramus and can cause life-threatening hemorrhage if inadvertently torn.

Question 59

A 40-year-old man with ankylosing spondylitis requires bilateral total hip arthroplasties for severe secondary osteoarthritis. Compared to osteoarthritis patients, this patient is at a significantly higher risk for which postoperative complication?

Explanation

Patients with ankylosing spondylitis or hypertrophic osteoarthritis have an elevated risk of developing heterotopic ossification following total hip arthroplasty. Prophylaxis with radiation or NSAIDs is routinely recommended for these patients.

Question 60

A 35-year-old man undergoes an open reduction and internal fixation for a displaced femoral neck fracture. To preserve the remaining blood supply to the femoral head, the surgeon must be mindful of the primary arterial supply. Which of the following vessels provides the primary blood supply to the adult femoral head?

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) provides the primary blood supply to the weight-bearing dome of the femoral head in adults. The artery of the ligamentum teres (from the obturator artery) provides a negligible supply in adults.

Question 61

A 28-year-old unrestrained driver is involved in a high-speed motor vehicle collision and sustains a posterior hip dislocation with an associated posterior wall acetabular fracture. Following reduction, the patient has a foot drop. Which of the following sensory deficits is most likely to be found on examination?

Explanation

Posterior hip dislocations most commonly injure the peroneal division of the sciatic nerve. The peroneal nerve provides motor innervation to the ankle dorsiflexors and sensory innervation to the dorsolateral leg and dorsum of the foot.

Question 62

A surgeon utilizes the anterior (Smith-Petersen) approach for an open reduction of a developmental dysplasia of the hip. What is the superficial internervous plane utilized in this approach?

Explanation

The superficial internervous plane for the Smith-Petersen approach is between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The deep plane is between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 63

A 22-year-old male collegiate hockey player presents with chronic groin pain exacerbated by prolonged sitting and pivoting. Examination reveals pain with hip flexion, adduction, and internal rotation (FADIR). Radiographs demonstrate an alpha angle of 65 degrees. Which of the following is the most likely primary pathology?

Explanation

An alpha angle greater than 55 degrees indicates asphericity of the femoral head-neck junction, characteristic of cam-type femoroacetabular impingement (FAI). This mechanically limits flexion and internal rotation, causing pain and labral pathology.

Question 64

A 65-year-old female presents with recurrent posterior instability of her total hip arthroplasty (THA). Radiographic evaluation reveals an anteversion angle of 5 degrees and an inclination angle of 40 degrees for the acetabular component. Which of the following is the most appropriate definitive management?

Explanation

The patient's acetabular component is relatively retroverted (normal anteversion is 15-20 degrees), predisposing her to posterior dislocation. The definitive management is revision of the acetabular component to establish appropriate anteversion.

Question 65

A 40-year-old woman with a history of systemic lupus erythematosus treated with corticosteroids presents with progressive hip pain. MRI reveals a double-line sign on T2-weighted images with no evidence of subchondral collapse or flattening of the femoral head. Which of the following joint-preserving interventions is most indicated?

Explanation

The patient has pre-collapse (Ficat Stage II) avascular necrosis of the femoral head. Core decompression is indicated to relieve intraosseous pressure and promote revascularization before subchondral collapse occurs.

Question 66

When stabilizing an acute anteroposterior compression (APC) type pelvic ring injury in a hemodynamically unstable patient, a pelvic binder should be centered over which of the following anatomic landmarks?

Explanation

To effectively reduce pelvic volume and stabilize the fracture, a pelvic binder must be applied and centered directly over the greater trochanters. Placement over the iliac crests may inadvertently widen the pelvic floor and worsen the deformity.

Question 67

A 78-year-old man sustains a reverse obliquity intertrochanteric femur fracture. Why is a cephalomedullary nail mechanically preferred over a sliding hip screw (SHS) for this fracture pattern?

Explanation

Reverse obliquity fractures lack an intact lateral wall to buttress the proximal fragment. A sliding hip screw would allow the femoral shaft to displace medially, leading to failure, whereas a cephalomedullary nail effectively stabilizes the lateral wall.

Question 68

During an ilioinguinal approach for an anterior column acetabular fracture, the surgeon must mobilize contents within three distinct surgical windows. Which of the following structures is primarily isolated and protected in the middle window?

Explanation

In the ilioinguinal approach, the lateral window contains the iliopsoas and femoral nerve, the middle window contains the external iliac vessels, and the medial window contains the spermatic cord (or round ligament) and inguinal canal contents.

Question 69

When performing a direct lateral (Hardinge) approach to the hip, proximal extension of the incision into the gluteus medius must be strictly limited to avoid injury to which of the following nerves?

Explanation

The superior gluteal nerve innervates the gluteus medius, minimus, and tensor fasciae latae. Proximal splitting of the gluteus medius more than 3-5 cm above the greater trochanter places this nerve at significant risk, which can lead to a persistent Trendelenburg gait.

Question 70

A 13-year-old obese boy undergoes in situ pinning with a single cannulated screw for a stable slipped capital femoral epiphysis (SCFE). Postoperatively, he develops severe, unrelenting hip stiffness and a dramatic loss of joint space on radiographs. Which of the following is the most likely cause of this complication?

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute loss of articular cartilage and severe stiffness. It is most strongly associated with unrecognized intra-articular hardware penetration during in situ fixation.

Question 71

A 60-year-old man presents with chronic lateral hip pain 5 years after a metal-on-polyethylene total hip arthroplasty. Serum inflammatory markers are normal, but a metal artifact reduction sequence (MARS) MRI reveals a large solid/cystic pseudotumor in the periprosthetic tissues. What is the most likely etiology of this finding?

Explanation

In a metal-on-polyethylene THA, adverse local tissue reactions (ALVAL/pseudotumors) are most commonly caused by trunnionosis. This is mechanically assisted crevice corrosion occurring at the modular head-neck junction.

Question 72

During an intrapelvic (modified Stoppa) approach for acetabular fracture fixation, significant hemorrhage is encountered while dissecting over the superior pubic ramus. This bleeding is most likely originating from an anastomosis (corona mortis) between which two vascular systems?

Explanation

The corona mortis is a critical vascular anastomosis connecting the external iliac (or inferior epigastric) vessels with the obturator vessels. It lies posterior to the superior pubic ramus and must be carefully ligated during intrapelvic approaches.

Question 73

A surgeon is counseling a young, active patient regarding bearing surface options for a planned total hip arthroplasty. If a ceramic-on-ceramic bearing is chosen, the patient should be counseled that compared to highly cross-linked polyethylene, ceramic-on-ceramic has a higher risk of which of the following?

Explanation

Ceramic-on-ceramic bearings offer the lowest wear rates and no risk of ALTR from metal ions. However, they carry unique risks of audible squeaking and catastrophic shattering (fracture) of the ceramic components.

Question 74

Following a cementless total hip arthroplasty, a patient sustains a displaced periprosthetic femoral fracture localized around the tip of a well-fixed femoral stem (Vancouver Type B1). What is the gold standard of treatment for this specific injury?

Explanation

Vancouver B1 periprosthetic fractures occur around a well-fixed stem. The treatment of choice is fracture osteosynthesis, typically achieved with a lateral locking plate and cerclage wires, leaving the stable implant in place.

Question 75

A 28-year-old man sustains a displaced Pauwels type III femoral neck fracture. What is the most appropriate definitive management to minimize the risk of avascular necrosis and nonunion?

Explanation

Young patients with displaced femoral neck fractures should undergo urgent ORIF to preserve the native femoral head. A fixed-angle device (such as a sliding hip screw with a derotational screw) provides better biomechanical stability against shear forces for highly vertical (Pauwels III) fractures.

Question 76

During a posterior approach to the hip, extreme external rotation of the femur places which of the following vascular structures at highest risk, potentially compromising the main blood supply to the adult femoral head?

Explanation

The deep branch of the medial circumflex femoral artery (MFCA) is the primary blood supply to the adult femoral head. It courses in close proximity to the obturator externus tendon and can be injured during deep dissection or excessive external rotation during the posterior approach.

Question 77

A 65-year-old woman sustains a posterior hip dislocation 4 weeks after undergoing primary total hip arthroplasty via a posterior approach. Radiographs show the acetabular cup has 10 degrees of anteversion and 45 degrees of abduction. What is the most likely cause of this instability?

Explanation

Normal acetabular cup position targets approximately 15-20 degrees of anteversion and 40-50 degrees of abduction. A cup with only 10 degrees of anteversion is under-anteverted (relatively retroverted), which predisposing the patient to posterior dislocation.

Question 78

A 35-year-old man is brought to the emergency department after a high-speed motor vehicle collision. He has a shortened, internally rotated, and adducted right lower extremity. Following closed reduction of the hip, he is noted to have a foot drop and inability to extend his great toe. Which specific nerve division is most likely injured?

Explanation

Posterior hip dislocations are associated with sciatic nerve injuries in 10-20% of cases. The peroneal division is anatomically lateral and more securely tethered at the sciatic notch, making it more susceptible to stretch injuries.

Question 79

Which of the following radiographic findings is pathognomonic for a both-column acetabular fracture?

Explanation

The spur sign represents the intact portion of the ilium that remains attached to the axial skeleton while the articular fragments are medially displaced. It is pathognomonic for a both-column acetabular fracture and is best visualized on the obturator oblique view.

Question 80

A 75-year-old woman presents with a reverse obliquity intertrochanteric femur fracture. Which of the following implants offers the most biomechanically stable fixation for this specific fracture pattern?

Explanation

Reverse obliquity intertrochanteric fractures are inherently unstable because the fracture geometry allows medial and distal displacement of the femoral shaft. A cephalomedullary nail acts as an intramedullary buttress, providing superior biomechanical stability and preventing excessive medial translation.

Question 81

An obese 13-year-old boy presents with left knee pain and a slight limp for 3 weeks. Examination of the hip reveals obligatory external rotation of the thigh during passive flexion of the hip. What is the most appropriate initial management?

Explanation

The clinical presentation is classic for a Slipped Capital Femoral Epiphysis (SCFE). Prompt in situ percutaneous pinning with a single screw is the standard of care to prevent further slippage and minimize complications.

Question 82

During an anterior (Smith-Petersen) approach to the hip, the superficial internervous plane lies between which two muscles?

Explanation

The superficial dissection for the Smith-Petersen approach utilizes a true internervous plane between the sartorius (innervated by the femoral nerve) and the TFL (innervated by the superior gluteal nerve). The deep plane is between the rectus femoris and gluteus medius.

Question 83

A 45-year-old man undergoes total hip arthroplasty with an alumina ceramic-on-ceramic bearing. At his 3-year follow-up, he complains of a high-pitched squeaking noise when walking. Which of the following factors is most strongly associated with this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is primarily associated with edge loading of the bearing surfaces. This typically results from component malposition (e.g., extreme cup anteversion or vertical placement), impingement, or loss of fluid lubrication.

Question 84

A 30-year-old woman with systemic lupus erythematosus on chronic corticosteroids presents with progressive groin pain. Radiographs show a subchondral lucent crescent in the anterosuperior aspect of the femoral head with mild flattening, but no joint space narrowing (Ficat Stage III). What is the most appropriate surgical treatment?

Explanation

Ficat Stage III AVN is characterized by structural collapse (the crescent sign and flattening). Once subchondral collapse occurs, head-preserving procedures like core decompression are generally ineffective, making total hip arthroplasty the most reliable option.

Question 85

During an ilioinguinal approach to the acetabulum, severe bleeding occurs as the surgeon dissects near the superior pubic ramus. This is most likely due to an injury to an anastomotic vessel connecting the obturator system and the:

Explanation

The corona mortis is a potentially fatal vascular anastomosis between the external iliac (or deep inferior epigastric) vessels and the obturator vessels. It is located on the posterior aspect of the superior pubic ramus and is highly vulnerable during the ilioinguinal approach.

Question 86

A 68-year-old man reports persistent lateral hip pain and a severe limp 6 months following a primary total hip arthroplasty via a direct lateral (Hardinge) approach. Examination reveals a positive Trendelenburg test. MRI with metal artifact reduction shows a complete, retracted tear of the abductor tendon insertion. What is the most appropriate next step after failing conservative care?

Explanation

Symptomatic, full-thickness, retracted abductor (gluteus medius/minimus) tendon tears that fail nonoperative management should be treated with open surgical repair. This helps restore the abductor lever arm and corrects the Trendelenburg gait.

Question 87

What is the biomechanical rationale for advising a patient with severe left hip osteoarthritis to hold a cane in their right hand?

Explanation

Using a cane in the contralateral hand creates an upward force that generates a torque opposing the body weight. This significantly reduces the necessary force output by the ipsilateral hip abductors, which in turn drastically lowers the total joint reaction force on the affected hip.

Question 88

A 55-year-old woman undergoes total hip arthroplasty. To achieve adequate soft tissue stability without over-lengthening the leg, the surgeon utilizes a high-offset femoral stem. Increasing femoral offset in total hip arthroplasty primarily achieves which of the following?

Explanation

Increasing the femoral offset mediatizes the femoral shaft relative to the center of rotation, which increases the lever arm of the abductor musculature. This improves soft tissue tension and abductor efficiency without significantly altering vertical leg length.

Question 89

In evaluating a patient with persistent anterior thigh pain 1 year after receiving an uncemented total hip arthroplasty, radiographs reveal reactive cortical hypertrophy at the distal tip of the femoral stem. The porous-coated proximal region shows bone ingrowth without radiolucencies. What is the most likely diagnosis?

Explanation

End-of-stem pain occurs typically with stiff, well-fixed uncemented stems. It is a result of a modulus mismatch between the rigid metal implant and the more elastic diaphyseal bone, leading to stress transfer and reactive cortical thickening at the stem tip.

Question 90

A 25-year-old male involved in a high-speed MVC sustains a type I Pipkin fracture-dislocation of the hip. Following closed reduction, a CT scan demonstrates a 1 cm displaced fracture fragment from the femoral head inferior to the fovea capitis, a concentrically reduced joint, and no intra-articular debris. What is the most appropriate management?

Explanation

Pipkin Type I fractures involve the femoral head inferior to the fovea (the non-weight bearing portion). If the hip joint is concentrically reduced and the fragment is small or does not mechanically block motion, nonoperative management with protected weight bearing is appropriate.

Question 91

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

Explanation

The predominant blood supply to the adult femoral head is the deep branch of the medial femoral circumflex artery (MFCA). This artery gives rise to the superior retinacular vessels, which supply the critical superolateral weight-bearing aspect of the femoral head.

Question 92

A 32-year-old man sustains a displaced, vertical (Pauwels type III) femoral neck fracture. Which of the following fixation constructs offers the highest biomechanical stability against shear forces for this specific fracture pattern?

Explanation

A sliding hip screw (SHS) with a derotation screw provides superior biomechanical stability against vertical shear forces seen in Pauwels type III fractures compared to parallel cancellous screws. This fixed-angle construct allows controlled impaction and significantly minimizes the risk of varus collapse.

Question 93

A 24-year-old male hockey player presents with groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate a 'crossover sign' and prominent ischial spine.

These radiographic findings are most characteristic of which of the following conditions?

Explanation

The 'crossover sign' and a prominent ischial spine are classic radiographic indicators of focal cranial acetabular retroversion. This structural abnormality leads to anterior overcoverage and secondary pincer-type femoroacetabular impingement (FAI).

Question 94

A 65-year-old woman undergoes a primary total hip arthroplasty via a direct lateral (Hardinge) approach. Postoperatively, she demonstrates a severe, persistent Trendelenburg gait. Iatrogenic injury to which of the following structures is the most likely cause?

Explanation

The direct lateral approach involves splitting the gluteus medius and minimus muscles. If the split extends more than 5 cm proximal to the tip of the greater trochanter, the superior gluteal nerve is at high risk of transection, leading to profound abductor weakness and a Trendelenburg gait.

Question 95

A 28-year-old man presents following a high-speed motor vehicle collision with a posterior hip dislocation and an associated fracture of the femoral head.

A computed tomography (CT) scan reveals that the femoral head fracture fragment is located caudad (inferior) to the fovea centralis. According to the Pipkin classification, this injury is classified as:

Explanation

A Pipkin type I fracture involves a femoral head fracture caudad to the fovea centralis, thus sparing the primary weight-bearing surface. Pipkin type II is cephalad to the fovea, type III involves a concurrent femoral neck fracture, and type IV includes an associated acetabular fracture.

Question 96

During a posterior approach to the hip for a total hip arthroplasty, the surgeon releases the short external rotators. To minimize the risk of iatrogenic injury to the ascending branch of the medial femoral circumflex artery (MFCA), the surgeon should strictly protect the superior border of which of the following muscles?

Explanation

The main arterial supply to the femoral head comes from the deep branch of the MFCA. Its ascending branch crosses the posterior aspect of the hip joint capsule near the superior border of the quadratus femoris muscle, making it highly vulnerable during extensive posterior dissection.

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

AAOS & ABOS Hip MCQs (Set 3): Anatomy, Pathology & Trauma | OITE Board Prep

Key Takeaway

AAOS & ABOS Hip MCQs (Set 3): Anatomy, Pathology & Trauma | OITE Board Prep

Chapter Index