How Effective is a Saline Arthrogram for Wounds Around the Knee?

Abstract

Traumatic arthrotomies may predispose patients to subsequent septic arthritis and therefore are regarded as serious injuries requiring emergent treatment. The saline arthrogram is a commonly used test to determine if a patient has a traumatic arthrotomy. We determined the sensitivity of the saline arthrogram to identify known intraarticular wounds in 78 patients (80 knees) undergoing elective arthroscopic procedures. There were 66 infrapatellar and 14 suprapatellar incisions. The average length of the incision was 7.5 mm. Intraarticular position was confirmed with a blunt probe. A saline arthrogram then was performed using 60 mL normal saline. The known arthrotomy (operative wound) was observed during the injection for evidence of saline leakage (positive static test). If no leakage was observed, the knee was brought through a range of motion with continued observation for leakage from the arthrotomy (positive dynamic test). Twenty-two of 80 knees had a positive test without passive range of motion of the knee (static sensitivity,

The volume of the human knee joint

“…The observed wide range of the knee volume (40-290 ml) explains the low sensitivity and specificity of the saline load test that is used to determine a traumatic capsule defect [9][10][11][12]. This problem limits the diagnostic value of the saline load test with reported cut-off values between 60 and 194 ml [9][10][11][12].…”

“…This problem limits the diagnostic value of the saline load test with reported cut-off values between 60 and 194 ml [9][10][11][12].…”

Sensitivity of the Saline Load Test With and Without Methylene Blue Dye in the Diagnosis of Artificial Traumatic Knee Arthrotomies

“…The detection rate in these studies is between 36% and 46% at clinically accepted volumes of 50 to 60 mL. [4][5][6] Our rate was only 33% at 180 mL, whereas other studies had an improved sensitivity in the 90% to 99% range at this volume. Nord et al used a dynamic test by putting the knee through a range of motion during injection, which may have accounted for their improved sensitivity at higher volumes (99% at 175 mL).…”

“…5 However, Tornetta et al still found very low sensitivity even when the dynamic test was used. 6 The static test was chosen for this study because the dynamic test was felt to introduce too many confounding variables, including cycling rate and range of motion in degrees. Also, the static test may be more clinically relevant in an awake patient who may not tolerate range of motion on a painful, injured knee.…”

“…4,5 Tornetta et al also found that injecting knees with a known arthrotomy with 60 mL of normal saline yielded a very low sensitivity. 6 The common theme among these studies is that the saline load test is not reliable for ruling out an open intra-articular knee injury.…”