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When performing a saline load test to evaluate for a traumatic arthrotomy of the knee, a mininum of how much saline should be utilized?
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A saline load test is commonly utilized to evaluate for intraarticular penetration of superficial lacerations (traumatic arthrotomies). In this technique, a large gauge needle is used (18 ga) and saline is injected into the knee with passive ROM provided. Saline egress from the soft tissue injury is a positive test (traumatic arthrotomy present).
The study by Nord et al found that the volumes of saline that were needed in order to effectively diagnose 75%, 90%, 95%, and 99% of the knee arthrotomies were 110, 145, 155, and 175 mL, respectively.
The other referenced study by Keese et al found that 50 mL of saline successfully identified only 46% of known knee arthrotomies and that 194 mL was needed to reach a 95% identification rate.
Nord RM, Quach T, Walsh M, Pereira D, Tejwani NC
J Bone Joint Surg Am. 2009 Jan;91(1):66-70. PMID: 19122080 (Link to Abstract)
Nord, JBJS 2009
Keese GR, Boody AR, Wongworawat MD, Jobe CM
J Orthop Trauma. 2007 Aug;21(7):442-3. PMID: 17762473 (Link to Abstract)
Keese, JOT 2007
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Average 2.0 of 49 Ratings
A 20-year-old man presents with erythema, swelling, and pain at the left sternoclavicular joint shown in Figure A. His temperature is 38.9 degress Celsius, serum WBC is 14,000, and his C-reactive protein is elevated. He reports that he uses IV heroin. A coronal 3D CT scan of the left clavicle is shown in Figure B. Joint aspiration shows many grams stain positive organisms. Which of the following organisms is the most likely pathogen?
Group B streptococcus
This patient has sternoclavicular joint septic arthritis with gram positive organisms. Although there is an increased incidence of Pseudomonas aeruginosa infection in IV drug users, S. aureus is still the most common organism.
Ross et al states "Staphylococcus aureus is now the major cause of sternoclavicular septic arthritis in intravenous drug users. Pseudomonas aeruginosa infection in injection drug users declined dramatically with the end of an epidemic of pentazocine abuse in the 1980s."
The referenced article by Goldin et al is from the New England Journal of Medicine reports that all of their cases of SC joint septic arthritis were in intravenous drug abusers and that P. aeruginosa grew out of 3 patients and S. aureus grew out of 1 patient.
A more recent article by Abu Arab et al reported that Staph aureus was most common even in IV drug users. The review article by Higginbotham and Kuhn note that risk factors for SC joint septic arthritis include hemodialysis, immunocompromise, alcoholism, and HIV. Neisseria gonorrhoeae, fungal, and candida present in HIV patients.
Treatment is I&D and appropriate antibiotics, although aspiration and abx have shown some success too. CT and MRI are useful in diagnosis, and open biopsy or aspiration is recommended for definitive diagnosis.
Higginbotham TO, Kuhn JE.
J Am Acad Orthop Surg. 2005 Mar-Apr;13(2):138-45. PMID: 15850371 (Link to Abstract)
Higginbotham, JAAOS 2005
Goldin RH, Chow AW, Edwards JE Jr, Louie JS, Guze LB.
N Engl J Med. 1973 Sep 20;289(12):616-8. PMID: 4198821 (Link to Abstract)
Goldin, NEJM 1973
Abu Arab W, Khadragui I, Echavé V, Deshaies A, Sirois C, Sirois M.
Eur J Cardiothorac Surg. 2011 Sep;40(3):630-4. Epub 2011 Mar 1. PMID: 21367613 (Link to Abstract)
Ross JJ, Shamsuddin H.
Medicine (Baltimore). 2004 May;83(3):139-48. PMID: 15118542 (Link to Abstract)
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Which of the following is true regarding the use of the saline injection load test to diagnose traumatic knee arthrotomies?
Addition of methylene blue to the saline load test increases the sensitivity of the test
Injection of 110ml of saline will diagnose 95% of knee arthrotomies
Injection of 175ml of saline will diagnose 99% of knee arthrotomies
A superomedial injection location requires significantly less fluid than a inferoeromedial injection location
A history and physical exam by an orthopaedic surgeon has equivalent sensitivity to saline load test at detecting a traumatic arthrotomy
Injection of 175ml of saline will diagnose 99% of knee arthrotomies.
Clinical evaluation alone to determine if a periarticular laceration has penetrated the joint can often be incorrect. A Saline Load Test (SLT) is an effective methods to detect intraarticular penetration. New studies have shown addition of methylene blue does not improve the diagnostic value of the saline load test. The use of a CT scan can be helpful, especially in the presence of intra-articular air.
Voit et al. investigated the sensitivity of the clinical exam and a saline load test in 50 consecutive patients with periarticular lacerations suggestive of joint penetration. In 14 there was leakage of fluid on saline load test. In six of these patients, the clinician had judged there was no traumatic arthrotomy based on physical exam and clinical history. They therefore concluded performing a saline load test is important adjunct and the clinical exam alone can not be relied on to detect traumatic arthrotomies.
Nord et al. found that the volumes of saline that were needed in order to effectively diagnose 75%, 90%, 95%, and 99% of the knee arthrotomies were 110, 145, 155, and 175 mL, respectively. They also found that an inferomedial injection location required significantly less fluid than a superomedial injection location did.
Metzger et al. studied 58 patients that underwent saline load test with about 100ml of saline injected (methylene blue 29, normal saline 29). They found that the false-negative rate was 67% (methylene blue 69%, normal saline 66%). They concluded the addition of methylene blue does not improve the diagnostic value of the saline load test.
Konda et al. performed a study evaluationg the role of CT scan versus saline load test. They found that the sensitivity and specificity of the CT scan to detect traumatic arthrotomy was 100%. In a subgroup of 37 patients that received both a CT scan and the conventional saline load test, the sensitivity and specificity of the CT scan was 100% compared to 92% for the saline load test (p<0.001).
Answer 1: Addition of methylene blue to the saline load test does not increase the sensitivity of the test. (Metzger et al.)
Answer 2: Injection of 110ml of saline will diagnose 75% of knee arthrotomies. (Voit et al.)
Answer 4: A inferoeromedial injection location requires significantly less fluid than a superomedial injection location (Nord et al.)
Answer 5: Physical exam performs worse than the conventional saline load test to detect traumatic knee arthrotomies
Voit GA, Irvine G, Beals RK.
J Bone Joint Surg Br. 1996 Sep;78(5):732-3. PMID: 8836059 (Link to Abstract)
Voit, BJJ 1996
Metzger P, Carney J, Kuhn K, Booher K, Mazurek M
J Orthop Trauma. 2012 Jun;26(6):347-9. PMID: 22215059 (Link to Abstract)
Metzger, JOT 2012
Konda SR, Davidovitch RI, Egol KA
J Orthop Trauma. 2013 Sep;27(9):498-504. PMID: 23287770 (Link to Abstract)
Konda, JOT 2013
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A 45-year-old IV drug abuser has sternoclavicular (SC) joint pain for the past 2 weeks. He is afebrile and physical exam findings include point tenderness and swelling. He most likely has septic arthritis of the sternoclavicular joint. If so, what is the most likely infecting organism?
Risk factors for sternoclavicular septic arthritis include IV drug abuse, diabetes, and HIV.
According to the reference by Ross et al, Staphylococcus aureus accounts for 49% of infections. SC joint arthritis accounts for 1% of septic arthritis in the general population but 17% in the IV drug abuse population. Symptoms include spontaneous swelling with the appearance of joint subluxation and localized pain. These patients are not uncommonly afebrile.
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