4.4 of 93 Ratings
When investigating a periprosthetic hip or knee joint infection, which marker is most sensitive and specific for infection?
Intraoperative frozen section
Serum interleukin-6 (IL-6)
C-reactive protein (CRP)
Leukocyte esterase (LE) colorimetric strip test
Select Answer to see Preferred Response
A 62-year-old woman presents to your clinic with knee pain and swelling 4 months after a primary TKA. Her initial recovery was uneventful, but she had a small pustule develop 6 weeks after surgery. An emergency room physician gave her 10 days of oral antibiotics for a "suture abscess" at that time. Since the ED visit, she notes worsening pain and persistent drainage. Figurs A represents a clinical photo from today's appointment. What is the next best step in management?
Admit directly from clinic for I&D and polyethylene exchange
Prescribe oral antibiotics and follow up in 2 weeks
Aspirate the patient's knee and plan for surgery
Prescribe home health wound care
Placement of a knee immobilizer and hold physical therapy for 2 weeks
A 64-year-old male is 6 months out from left total knee arthroplasty. He has had at least two months of pain and swelling to the operative joint. In your initial workup, he is found to have a well-healed surgical incision, a serum CRP of 13mg/L and an ESR of 19mm/h. You perform arthrocentesis, which results in a negative alpha-defensin, synovial WBC of 1000 cells/µL, synovial PMNs of 90%, and synovial CRP of 4mg/L. What is the next best step in management?
Proceed to OR for histologic examination
Proceed with two stage revision
Proceed with single stage polyethylene exchange with irrigation and debridement
6 weeks of IV antibiotics
A 60-year-old male with history of renal transplantation and previous intravenous drug abuse undergoes total knee arthroplasty. Two years later, he begins to have mild knee pain and low-grade swelling that persists for 10 months before he finally comes to the emergency room. Examination reveals no fever. Range of motion is 5 to 70 degrees. Erythrocyte sedimentation rate is 22mm/h, and C-reactive protein is 0.8mg/L. Knee aspiration reveals 12,000/mm3 nucleated cells with 76% neutrophils. Gram stain is negative and aerobic and anaerobic cultures are negative after 4 days in culture. His symptoms do not resolve after 5 days of empiric intravenous antibiotics and he is taken to the operating room for arthroscopic irrigation and debridement. Operative synovial tissue cultures are shown in Figure A. What is the best next step?
Cessation of immunosuppressant medication, lifelong antimycobacterial suppression
Open irrigation and debridement, implant retention and lifelong antifungal suppression
Open irrigation and debridement, resection arthroplasty, antimycobacterial drugs for 6 to 12 months
Open irrigation and debridement, single-stage exchange, antifungal drugs for 6 to 12 months
Open irrigation and debridement, two-stage exchange, antifungal drugs for 6 to 12 months
Increasing the porosity of a cement spacer for an infected total knee arthroplasty leads to which of the following?
Increased elution of antibiotics
Increased cement density
Improved cement-prosthesis bonding
Increased reinfection rate
A 68-year-old woman underwent a right total knee arthroplasty 5 years ago and has increasing right knee pain over the past 2 months. Radiographs are seen in Figures A and B, respectively. Laboratory studies demonstrate a C-reactive protein of 10 mg/dL (normal < 2.0 mg/dL) and an erythrocyte sedimentation rate of 50 mm/h (normal < 20 mm/h). Knee aspiration shows white blood cell count of 3,400/mm3 with 90% polynuclear cells. The patient's gram stain and cultures are negative. What is the most appropriate next step in management?
Irrigation and debridement with polyethylene spacer exchange
One-stage revision with antibiotic impregnated cement
One-stage revision with direct antibiotic infusion into knee joint via hickman catheter
A 50-year-old woman underwent cemented total knee arthroplasty 3 weeks ago. She reports that she has 1 week of drainage the size of a quarter on a gauze pad that she places over the incision three times daily. Her body mass index is 53 and her medical problems include hypertension and type 2 diabetes. Blood work shows a CRP of 1.1mg/L (normal 1-3mg/L). Knee aspiration yields WBC of 673 cells/mm(3) with 30% polymorphonucleocytes, and a negative gram stain. There is no surrounding erythema but there is a 1cm area at the inferior aspect of the wound that has a large amount of serous drainage able to be expressed. She has a painless range of motion is 0° to 117°. What would be the next most appropriate step in management?
Removal of all components with antibiotic spacer placement and staged revision
One-stage irrigation and debridement with removal of components to a cementless prosthesis
Empiric oral antibiotics for 4 weeks and steri-strips over the area of drainage
Surgical exploration with debridement and possible polyethylene exchange
Bone scan and repeat aspiration with empiric intravenous antibiotics for 4 weeks
A 72-year-old man reports persistent, progressively worsening pain in his hip after undergoing a total hip arthroplasty 15 months ago. A current AP hip radiograph is shown in Figure A. What is the next most appropriate step in the care of this patient?
Obtain serum metal ion values
Obtain ESR, CRP, and WBC
Obtain CT and MRI of the hip
Urgent debridement and component explantation
A 64-year-old female underwent a total knee arthroplasty 4 years ago and has increasing pain for the past 6 months. Knee aspiration reveals 4,000 leukocytes with 80% polymorphonucleocytes and a 2-stage revision arthroplasty is planned. When comparing articulating cement spacers to static spacers following resection, all of the following are potential advantages of articulating spacers EXCEPT
Decreased quadriceps shortening
Decreased rate of infection recurrence
Increased knee range of motion for duration of cement spacer implantation
Better maintenance of joint space
Decreased exposure time during reimplantation
A 65-year-old woman complains of worsening left knee pain 7 months following total knee arthroplasty. She reports good pain relief for the initial 5 months following surgery. Physical exam is notable for a stable knee with range of motion from 0-115 degrees. Radiographs are provided in Figures A and B. Which of the following is the most appropriate next step in management?
Nuclear bone scan
One stage revision total knee arthroplasty
CRP, ESR, WBC
Physical therapy with focus on range of motion and quadriceps strengthening
A 65-year-old male presents with a painful right total knee arthroplasty, which was performed ten years ago. CRP is 15 mg/L. Knee aspiration reveals a purulent fluid with 3,100 WBC's with 83% PMN's. Culture results are pending. Which of the following is the best management option?
Physical therapy, ice, and follow-up evaluation in 2 weeks
Repeat aspiration if cultures are positive
Surgical explant of components
A 65-year-old male who had a total knee arthroplasty 8 years ago comes into the office with worsening knee pain. The orthopaedic surgeon is concerned about infection and aspirates the knee. Which of the following are the lowest laboratory values from a synovial aspirate suggestive of infection?
WBC of 500 cells/ml and PMN 25%
WBC of 1,000 cells/ml and PMN 25%
WBC of 1,500 cells/ml and PMN 70%
WBC of 5,000 cells/ml and PMN 70%
WBC of 25,000 cells/ml and PMN 70%
A 68-year-old man with no significant medical history underwent a total knee arthroplasty 4 years ago. A radiograph is shown in Figure 55. He reports that he had no problems with the knee until 6 weeks ago when he noted the gradual onset of pain following a colonoscopy. Examination reveals a painful, swollen knee. Knee aspiration reveals a WBC count of 40,000/mm3. Management should consist of
open irrigation and debridement with polyethylene exchange.
one-stage resection arthroplasty and reimplantation.
two-stage resection arthroplasty and reimplantation.
arthroscopic irrigation and debridement.
Antibiotic-loaded bone cement prostheses, such as that shown in Figure 8, are best created by using which of the following methods?
Using commercially available antibiotic-loaded bone cement
Adding 0.5 g vancomycin to commercially available antibiotic-loaded bone cement
Adding 0.5 g tobramycin and 0.5 g vancomycin/unit of standard bone cement
Adding either 1.0 g vancomycin or 1.2 g tobramycin per 40 g of standard bone cement
Adding a minimum of 3.6 g tobramycin and 1.0 g vancomycin per 40 g of bone cement
Which of the following total hip arthroplasty patients appropriately meets the criteria for a surgical debridement with isolated femoral head and polyethylene liner exchange?
Prosthesis infection of 4 months duration
Prosthesis infection 8 weeks following implantation
Prosthesis infection 3 days following a systemic infection
Acetabular component loosening due to osteolysis
Vancouver Type A periprosthetic fracture.
A 64-year-old woman with osteoarthritis underwent bilateral total knee replacement 3 years ago. Current radiographs are shown in Figure A. She reports a 3-month history of bilateral knee pain while at rest and increasing swelling in the knees. Her ESR and CRP are elevated and bilateral knee aspiration cultures reveal Staphylococcus aureus. What is the most likely outcome if the patient undergoes simultaneous, bilateral knee resection arthroplasty with cement spacer and a course of intravenous antibiotics?
Prosthesis reimplantation with need for multiple surgical debridements at 2-year follow-up
20% risk of above knee amputation
Retention of antibiotic cement spacer and low chance of successful prosthesis reimplantation at 2-year follow-up
50% rate of conversion to knee fusion following resection arthroplasty
Successful prosthesis reimplantation at 2-year follow-up with less than 20% revision rate
A 72-year-old male presents 2 years status post fixation of an impending pathologic right femur fracture due to metastatic renal cell carcinoma. He is minimally ambulatory due to pain. Despite radiation therapy, there has been progression of the lesion with extensive cortical bone loss, which is shown in Figure A. A proximal femoral replacement arthroplasty is performed without complications, and is demonstrated in Figure B. Which of the following is true regarding this patients post-operative course?
Deep prosthetic infection is the most common complication
Mean Harris Hip score will likely not improve
The patient will most likely continue to be minimally ambulatory
Aseptic failure rate at 5 years is >50%
Pre-operative radiation decreases the risk of infection post-operatively
A 67-year-old diabetic male presents 4 months status post right total knee arthroplasty (TKA) complaining of pain and stiffness for the last four weeks. A clinical photograph is shown in Figure A. Radiographs and a bone scan are shown in Figures B, C and D. Blood work shows an ESR of 14mm/hr (normal 0-12mm/hr) and a CRP of 2mg/L (normal 1-3mg/L). Knee aspiration yields WBC of 1000, 30% PMNs, and a negative gram stain. He finished a 14-day course of antibiotics prescribed to him by his primary care physician one week ago. Which of the following is the most appropriate next step in management?
Broad-spectrum, empiric oral antibiotics
Repeat aspiration after one week
Irrigation and debridement of the right knee with a polyethylene liner exchange
One-stage irrigation and debridement of the right knee with a component exchange
Two-stage component removal, antibiotic spacer placement and subsequent revision
A 58-year-old man has significant pain and stiffness after undergoing right total knee arthoplasty 6 months ago. A current radiograph and bone scan are shown in Figures A and B. Labs show an ESR of 45mm/hr (normal 0-20) and a CRP of 13.5 mg/l(normal <10). Knee aspiration reveals a WBC count of 850 cells/mm(3) with 70% polymorphonuclear cells and no growth on culture. What is the next most appropriate step in management?
Two-stage component removal, antibiotic spacer placement and subsequent revision
Observation with repeat ESR and CRP in one week
Surgical debridement and polyethylene exchange only
Repeat aspiration and culture
One-stage irrigation and debridement with exchange of all components