This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 881
Topic: 3. Adult Reconstruction (Hip & Knee)
During a primary total knee arthroplasty, using a measured resection technique, the surgeon evaluates the trial components. The knee is found to be perfectly balanced in full extension but excessively tight in 90 degrees of flexion. Which of the following adjustments is the most appropriate next step to balance the knee?
Correct Answer & Explanation
. Downsize the femoral component using an anterior referencing system and/or release the posterior cruciate ligament
Explanation
A tight flexion gap with a balanced extension gap requires increasing the flexion gap volume exclusively. This can be achieved by downsizing the femoral component (to decrease the posterior condylar offset), releasing the PCL (in a CR knee), or increasing the posterior slope of the tibia.
Question 882
Topic: Total Hip Arthroplasty (THA)
A 54-year-old male who underwent a ceramic-on-ceramic total hip arthroplasty 3 years ago reports a loud, audible squeaking sound from his hip when walking or bending. What acetabular component orientation is most strongly associated with the onset of this specific phenomenon?
Correct Answer & Explanation
. High cup inclination and high cup anteversion
Explanation
Squeaking in ceramic-on-ceramic THA is highly associated with edge loading of the components. Edge loading most frequently occurs when the acetabular cup is placed in excessive inclination (steep angle) and excessive anteversion.
Question 883
Topic: Total Knee Arthroplasty (TKA)
A 68-year-old male presents with recurrent knee effusions and a sensation of the knee 'giving way' when descending stairs, 18 months after a primary posterior-stabilized TKA. Ligamentous examination demonstrates excessive anterior-posterior translation in 90 degrees of flexion, but the knee is perfectly stable in full extension. Radiographs show no loosening. What technical error during the index procedure is the most likely cause of this instability?
Correct Answer & Explanation
. Excessive resection of the posterior femoral condyles
Explanation
Flexion instability (stable in extension, unstable in flexion) in TKA is typically caused by a loose flexion gap. The most common technical error leading to this is excessive resection of the posterior femoral condyles or undersizing the femoral component in the AP plane.
Question 884
Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old female with a previous L2-to-pelvis fusion undergoes a primary total hip arthroplasty (THA). Because of her lumbopelvic stiffness, her pelvis fails to retrovert when transitioning from a standing to a sitting position. To minimize the risk of anterior impingement and subsequent posterior dislocation during sitting, how should the acetabular component positioning be adjusted?
Correct Answer & Explanation
. Increased anteversion
Explanation
A stiff lumbopelvic spine fails to retrovert during sitting, meaning the acetabular cup does not functionally open (antevert) to accommodate hip flexion. This increases the risk of anterior impingement and posterior dislocation, necessitating greater component anteversion during surgery.
Question 885
Topic: 3. Adult Reconstruction (Hip & Knee)
A 51-year-old woman who underwent a total knee arthroplasty 14 months ago for severe degenerative arthritis now reports progressive pain, swelling, and buckling of the knee. She must use crutches and is unable to negotiate stairs. Laboratory testing reveals a normal erythrocyte sedimentation rate and C-reactive protein. Radiographs of the patient are shown in Figures 17a through 17c. What is the most important test to further evaluate this problem?
Correct Answer & Explanation
. Axial CT views from the supracondylar distal femur to the proximal tibia below the tibial tubercle
Explanation
The cause of subluxation in this patient is multifactorial, and includes a laterally positioned patellar component, a tibial tray that is internally rotated and translated to the medial side of the proximal tibial surface, and a femoral component that is markedly internally rotated about 10 degrees. All of these findings will be apparent on a CT scan. The long standing radiograph may be helpful but does not show the particular rotational abnormalities of both implants that are causing this problem. Fluoroscopic review may show how unstable the patella is, but the initial Merchant’s view shows the basic problem. A bone scan does not provide information about component malposition. An MRI scan is inferior to a CT scan because of image artifact.
Question 886
Topic: Total Hip Arthroplasty (THA)
A patient has a painful metal-on-metal (MOM) left total hip arthroplasty (THA). Which test(s) best correlate with prognosis if this patient is having a reaction to metal debris?
Correct Answer & Explanation
. Metal artifact reduction sequence (MARS) MRI
Explanation
DISCUSSIONPainful MOM THA and taper corrosion can cause substantial damage to a patient's hip if left untreated. In this case, the workup for a painful MOM THA starts the same as a workup for a painful metal-on-polyethylene bearing couple. Infection must be ruled out in every case with a set of inflammatory markers. If these markers are remotely elevated, this is an indication for joint aspiration. In patients with metal debris, the pathology report often indicates too many cells to count or cellular debris. Metal ion levels do not seem to correlate with prognosis. There are well-functioning patients with high ion levels and poor-functioning patients with low ion levels. Advanced imaging with MARS MRI to evaluate for peritrochanteric fluid collection, a soft-tissue mass, or synovial/capsular hypertrophy will reveal signs of a metal reaction that indicate the need for a revision discussion. A CT scan can show more advanced bony destruction as an indicator of poor prognosis. These films can be used to determine the need for a structural graft or augments for reconstruction of bone loss attributable to metal debris.
Question 887
Topic: 3. Adult Reconstruction (Hip & Knee)
A year old woman undergoes revision total knee arthroplasty for tibial component aseptic loosening. She is concerned about recurrent loosening, and tibial stem fixation options during revision are reviewed. Figure below displays a radiograph of the revision technique used for this patient. What is the incidence of intraoperative tibial shaft fracture that is associated with this type of revision surgery?
Correct Answer & Explanation
. 0% to 1% with press-fit tibial stems B. 3% to 5% with press-fit tibial stems C. 3% to 5% with cemented tibial stems
Explanation
DISCUSSION:Using press-fit tibial stems during a hybrid revision total knee arthroplasty is associated with a 3% to 5% incidence of intraoperative tibial shaft fracture. Diaphyseal fixation of press-fit stems has the advantage of setting component alignment, dispersing forces on the proximal tibia, and offers excellent clinical results. The disadvantages include proximal and distal tibia anatomic mismatch and tibial shaft fracture. Cipriano and associates reported a tibial shaft fracture incidence of 4.9% in a series of 420 consecutiveknee revisions. All fractures healed with nonsurgical management, and none led to implant loosening. In this patient, it is important to recognize on the radiograph that this technique is a hybrid method of revision total knee arthroplasty, with cementation along the tibial tray and metaphysis and with press-fit fixation of the diaphyseal engaging stem. Then, it is important to know the risk and management of intraoperative diaphyseal tibial fractures. Cemented tibial stems are associated with a low rate of intraoperative fracture, because the implant is typically undersized to allow for an appropriate cement mantle. Option C is incorrect, because this revision is not cemented. Option A underestimates the incidence of fracture,whereas D overestimates the rate of fracture.
Question 888
Topic: Total Knee Arthroplasty (TKA)
For this patient, which TKA design is most appropriate?
Correct Answer & Explanation
. Posterior substitution TKA
Explanation
DISCUSSION: TKA in the setting of valgus deformities poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when used as a rotational reference point, can lead to internal rotation of the femoral component if not recognized. This malrotation will in turn lead to patellofemoral maltracking or instability, which is a common complication associated with primary TKA. The deformity is too severe to consider a bicruciate-retaining TKA or unicompartmental arthroplasty and does not necessitate a hinged TKA.
Question 889
Topic: 3. Adult Reconstruction (Hip & Knee)
Total hip arthroplasty is most appropriate for the injury shown in Figure A for which of the following patients?
Correct Answer & Explanation
. year-old female golf instructor
Explanation
Figure A is an AP radiograph demonstrating a displaced femoral neck fracture. Active older patients who present with a displaced femoral neck fracture should be treated with total hip arthroplasty (THA).Displaced femoral neck fractures can present a challenge to treat. In younger patients with good bone stock a closed vs. open reduction and internal fixation should be attempted. For active older patients a total hip arthroplasty is the best option, especially if there is pre-existing arthritis in the injured hip. THA provides the best function with the least pain and less need for repeat surgery (compared to hemiarthroplasty). For low-demand or debilitated patients, for patients older than age 80, or for those who can not reliably follow hip precautions a hemiarthroplasty provides the lowest risk of dislocation, and thus would be the treatment of choice.Macaulay et al. present a prospective randomized trial of patients with femoral neck fractures treated with THA vs hemiarthroplasty. They found that functional outcomes and patient satisfaction were higher in the THA group without significant increased risk of complications. Inclusion criteria required patients to be over age 50, be a community ambulator, and were excluded for presence of dementia.Abboud et al. retrospectively reviewed patients treated with THA for osteoarthritis and compared them to patients treated with THA for a femoral neck fracture. They found no significant difference between the two groups for outcomes or complications.Figure A is an AP radiograph demonstrating a displaced femoral neck fracture.Incorrect Answers:
Question 890
Topic: 3. Adult Reconstruction (Hip & Knee)
The patient develops an inability to dorsiflex her foot 2 days after surgical intervention while she is sitting in a chair after physical therapy. Initial treatment should consist of
Correct Answer & Explanation
. transferring back to bed with the head of the bed level and the surgical knee flexed.
Explanation
DISCUSSIONGamma irradiation produces free radicals. Although these free radicals can form cross-links with other polyethylene chains, the free radicals can also form a bond with oxygen, resulting in early oxidation. Gamma irradiation in air produces the highest risk for oxidized polyethylene, resulting in the highest risk for wear, delamination, and subsequent osteolysis.This patient demonstrates severe periarticular osteolysis. When she is asymptomatic, this suggests the acetabular and femoral components remain well fixed to the bone. Consequently, she can be treated by removing the wear generator (polyethylene exchange), along with bone grafting of the osteolytic defect. Considering the extensive amount of osteolysis, observation for 1 year would not be appropriate.The psoas is the anatomic structure that runs anterior to the acetabulum. The femoral neurovascular structures are at risk if the retractor is placed anterior and inferior to the psoas tendon.The patient develops a foot drop 2 days after surgery. As a result, it can be assumed that the nerve was not injured directly during the surgical procedure. Although MR imaging or a CT scan may be indicated to identify an evolving hematoma, the immediate concern is to minimize pressure on the sciatic nerve. Tension on the nerve can be decreased by flexing the surgical knee and positioning the bed flat.
Question 891
Topic: 3. Adult Reconstruction (Hip & Knee)
A 50-year-old woman who underwent a joint replacement of the hallux metatarsophalangeal joint 6 months ago now has pain and swelling about the great toe. Radiographs are shown in Figures 39a and 39b. What is the next most appropriate step in management?
Correct Answer & Explanation
. Arthrodesis of the hallux metatarsophalangeal joint with interposition bone graft
Explanation
DISCUSSION: The radiographs show displacement of the prosthesis, and there has been large amounts of bone resected to insert the implant. Arthrodesis is indicated with interposition bone graft to stabilize the joint and restore length to the first ray. REFERENCE: Myerson MS: Foot and Ankle Disorders. Philadelphia, PA, WB Saunders, 2000, pp 265-266.
Question 892
Topic: Total Knee Arthroplasty (TKA)
Figure below shows the standing AP radiograph obtained from a 55-year-old man who has a 5-year history of daily left knee medial joint line pain with weight-bearing activities. He denies night pain or symptoms of instability. On examination, his range of motion is 0° to 140°. He has a mild, fully correctable varus deformity and a negative Lachman test result. Nonsurgical treatment has failed. Unicompartmental knee arthroplasty (UKA) is discussed with the patient. The most appropriate next radiographic evaluation should be
Correct Answer & Explanation
. a stress radiograph to evaluate correction of the varus deformity.
Explanation
DISCUSSION: A patient with medial compartment arthritis and a correctable varus deformity with no clinical or examination findings of knee instability most likely has an intact anterior cruciate ligament (ACL). The pattern of medial compartment osteoarthritis most commonly associated with an intact ACL is that of anteromedial osteoarthritis. An incompetent ACL is commonly associated with a fixed varus deformity and radiographic signs of posteromedial wear. An incompetent ACL is a relative contraindication to a mobile-bearing UKA. When evaluating patients for a mobile-bearing UKA, a stress radiograph aids the orthopaedic surgeon in determining the correction of the varus deformity and assessing the lateral compartment. An inability to fully correct the deformity or narrowing of the lateral compartment with valgus stress should influence the surgeon against UKA. Joint registries across the world have shown decreased survivorship associated with TKA and UKA in men compared with other age groups, but survivorship is lower for UKA than for TKA. No studies to date have shown any differences in survivorship between fixed-bearing and mobile-bearing UKAs. The complication that is unique to mobile-bearing UKA is bearing spinout, which occurs in less than 1% of mobile-bearing UKA procedures. In vivo and in vitro polyethylene wear in mobile-bearing UKA are low. Arthritis may progress faster in patients with mobile-bearing UKAs than in those with fixed-bearing UKAs.
Question 893
Topic: 3. Adult Reconstruction (Hip & Knee)
A 32-year-old man has posttraumatic arthritis after undergoing open reduction and internal fixation of a left acetabular fracture. A total hip arthroplasty is performed, and the radiograph is shown in Figure 18. What is the most common mode of failure leading to revision in this group of patients?
Correct Answer & Explanation
. Acetabular component loosening
Explanation
DISCUSSION: Acetabular component loosening has been reported as the most common mode of failure following total hip arthroplasty in patients with a previous acetabular fracture. Following acetabular fracture and subsequent open reduction and internal fixation, the bone quality and vascularity are compromised, thus reducing the success rate of acetabular component cementless fixation. REFERENCES: Jimenez ML, Tile M, Schenk RS: Total hip replacement after acetabular fracture. Orthop Clin 1997;28:435-446. Romness DW, Lewallen DG: Total hip arthroplasty after fracture of the acetabulum: Long-term results. J Bone Joint Surg Br 1990;72:761-764.
Question 894
Topic: 3. Adult Reconstruction (Hip & Knee)
A sedentary 60-year-old woman has had good elbow function and pain relief after undergoing an ulnohumeral interposition arthroplasty 10 years ago. However, she currently reports pain and stiffness for the past 6 months, and nonsurgical management has failed to provide relief. Examination reveals range of motion of 40 to 110 degrees of flexion with pain during the entire range. Radiographs are shown in Figures 43a and 43b. What is the next most appropriate step in management? Review Topic
Correct Answer & Explanation
. Semiconstrained total elbow arthroplasty
Explanation
The patient had a good outcome after interposition arthroplasty but has now progressed to end-stage arthritis with loss of joint space and instability. A conversion to semiconstrained total elbow arthroplasty is most reliable for pain relief and improved function. In the setting of ligamentous instability, an unconstrained prosthesis will fail. Revision interposition ulnohumeral arthroplasty and arthroscopic debridement or open debridement, as in the Outerbridge-Kashiwagi procedure, are not reliable in this age group with this amount of joint space loss.
Question 895
Topic: 3. Adult Reconstruction (Hip & Knee)
What is the most common short-term complication following femoral impaction grafting for revision total hip arthroplasty?
Correct Answer & Explanation
. Periprosthetic fracture
Explanation
DISCUSSION: Impaction grafting is an alternative for severe femoral bone deficiency; however, stem subsidence is commonly observed during the first few months. Slight subsidence is felt to be integral to the success of the procedure. Predictable bone graft incorporation and stable stem fixation have been reported in the medium-term. The incidence of periprosthetic fractures has been reported as high as 24%. REFERENCES: Mikhail MWE, Weidenhielm L, Jazrawi LM, et al: Collarless, polished, tapered stem failure. J Bone Joint Surg Am 2000;82:1513-1514. Leopold SS, Rosenberg AG: Current status of impaction allografting for revision of a femoral component. Instr Course Lect 2000;49:111-118.
Question 896
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 16 shoes the AP radiograph of a 32-year-old man with a fracture cephalad to the fovea of the femoral head. A CT scan shows a single head fragment. After closed reduction of the hip, there is 5 mm of residual articular incongruity. Management should now include
Correct Answer & Explanation
. Open reduction through an anterior approach to the hip
Explanation
There seems to be no controversy in treating Pipkin 3 and 4 femoral head fractures. These are treated with an ORIF in concert with the femoral neck fracture or the acetabular fracture respectively. The difficulty stems in how to treat types land 2. In their review the authors recommend that residual joint incongruity of >2mm or an unstable hip requires and ORIF; their preferred approach was anterior. Swiontkowski Thorp Hansen Operative management of displaced femoral head fractures. J Orthopaedic Trauma. 1992 Vol 6 No 4; 437442
Question 897
Topic: Total Hip Arthroplasty (THA)
A patient has pain 2 years after undergoing a metal-on-metal (MOM) left total hip arthroplasty (THA). Which test(s) best correlate with a prognosis if this patient is having a reaction to metal debris?
Correct Answer & Explanation
. Erythrocyte sedimentation rate, C-reactive protein, and white blood cell count
Explanation
Painful MOM THA and taper corrosion can cause substantial damage to a patient's hip if left untreated. In this case, the workup for a painful MOM THA starts the same as a workup for a painful metal-on-polyethylene bearing couple. Infection must be ruled out in every case with a set of inflammatory markers. If these markers are remotely elevated, this is an indication for joint aspiration. In patients with metal debris, the pathology report often indicates too many cells to count or cellular debris. Metal ion levels do not seem to correlate with prognosis. There are well-functioning patients with high ion levels and poor-functioning patients with low ion levels. Advanced imaging with MARS MRI to evaluate for peritrochanteric fluid collection, a soft-tissue mass, or synovial/capsular hypertrophy will reveal signs of a metal reaction that indicate the need for a revision discussion. A CT scan can show more advanced bony destruction as an indicator of poor prognosis. These films can be used to determine the need for a structural graft or augments for reconstruction of bone loss attributable to metal debris.
Question 898
Topic: 3. Adult Reconstruction (Hip & Knee)
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
Correct Answer & Explanation
. C-reactive protein and a sed rate.
Explanation
DISCUSSION: 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. REFERENCE: Fitzgerald RH Jr: Infected total hip arthroplasty: Diagnosis and treatment. J Am Acad Orthop Surg 1995;3:249-262.
Question 899
Topic: 3. Adult Reconstruction (Hip & Knee)
A patient who underwent total knee arthroplasty now reports a loss of sensation in the area circled in Figure 38. This area is innervated by which of the following nerves?
Correct Answer & Explanation
. Infrapatellar branch of the saphenous
Explanation
DISCUSSION: The saphenous nerve follows the saphenous vein, giving off the infrapatellar branch that crosses the knee anteriorly to supply the peripatellar skin. A longitudinal incision can interrupt the nerve, leaving the terminal distribution without sensation. REFERENCE: Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, pp 140-150.
Question 900
Topic: 3. Adult Reconstruction (Hip & Knee)
Figures A and B show the six-month follow-up radiographs of a 62-year-old woman who sustained a hip fracture in a fall. Prior to the fall, the patient was active and had no difficulty with ambulation. The patient underwent open reduction and internal fixation with a sliding hip screw device. She has difficulty with ambulation, continues to walk with a walker, and reports startup pain. What is the most appropriate management at this time? Review Topic
Correct Answer & Explanation
. Conversion to total hip arthroplasty with a long cementless stem
Explanation
The radiographs demonstrate a healed fracture with penetration of the screw through the femoral head into the acetabulum as well as osteonecrosis and collapse of the femoral head (Figure 129b). Conversion to total hip arthroplasty with a long stem is necessary to bypass the femoral cortical defects from the screw holes. A primary tapered stem is not appropriate because of the proximal femoral deformity and the stress risers associated with the screw holes. Removal of hardware, valgus osteotomy, and revision of the internal fixation are not appropriate in the presence of the femoral head collapse and acetabular penetration.
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