Please rate topic.
Average 4.4 of 79 Ratings
Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine
You have 100% on this question. Just skip this one for now.
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
Select Answer to see Preferred Response
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.
A patient who underwent a total knee arthroplasty for osteoarthritis 18 months ago now reports the sudden development of pain in the ipsilateral knee. Radiographs and examination of the knee are unremarkable. Aspiration of the synovial fluid 3 days later reveals a WBC count of 1,500/mm3. The cells consist of 30% neutrophils and 70% monocytes. Culture results will not be available for several days. The patient has not been on antibiotics prior to this point. Based on these findings, what is the most appropriate management?
Arthrotomy, debridement, and polyethylene exchange
One-stage exchange arthroplasty
Two-stage exchange arthroplasty
Nonsurgical management without antibiotics
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