Summary
Dynamic HR ultrasound is giving information on dynamic instability
Abstract
Objectives The aim of this study is to determine the diagnostic accuracy of dynamic high resolution ultrasound imaging for detecting partial and complete ACL tears by direct visualization with a high resolution ultrasound probe.
Methods
Two hundred forty-seven patients presenting with intra articular knee complaints, who underwent dynamic ultrasound imaging as well as arthroscopy for any intra-articular knee pathology, were retrospectively evaluated. We differentiated between partial and complete ACL tears. In case of acute swelling maximum flexion imaging was performed after cooling down of the knee ( around 2 weeks after injury ) In intact ACL the ACL moves vertical against Hoffa fat pad pushing forward. In the torn ACL the loss of resistance of the ACL is detected by Hoffa moving in the opposite direction while the tibia subluxates anterior.
Results
Dynamic ultrasound imaging revealed 95 of 108 arthroscopically confirmed ACL tears (sensitivity 88%, specificity 82%, positive predictive value (PPV) 79%, negative predictive value (NPV) 90 .Sensitivity of US in the detection of partial ACL tears was 52%, specificity 85%, PPV 52%, NPV 84% . Complete ACL tears were depicted with a sensitivity of 79%, specificity of 89%, PPV of 63%, NPV of 95% .
Conclusion
The excellent NPV for complete ACL tears indicates that dynamic ultrasound imaging can be used as an initial imaging tool. We validated the use of high resolution ultrasound to differentiate between partial ACL tears, complete ACL tears and no tears..