Accuracy of a New Stress Radiographic Device in
Diagnosing Anterior Cruciate Ligament Tear
Pinij Srisuwanporn MD*, Sittichai Wachiratarapadorn MD**, Roongroj Panyasakulwong MD**,
Banchong Thuntong MSc***, Sukorm Cheecharern MD*, Weera Precha MD*
Affiliation :
* Department of Orthopaedics, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok, Thailand
** Fellowship in Sports Medicine, Department of Orthopaedics, Rajavithi Hospital,
College of Medicine, Rangsit University, Bangkok, Thailand
*** Biomedical Engineering, Rajavithi Hospital, Bangkok, Thailand
Background : Anterior cruciate ligament (ACL) tears are clinically diagnosed by detection of anterior tibial translation on
physical examination; however, this manual method of assessment is imprecise, subjective, and not reproducible. Recently
a new instrument, a stress radiographic device (SRD), was produced to objectively measure these displacements.
Objective : To assess a new instrument, a SRD, in the measurement of anterior tibial translation in ACL-deficient knee
compared to the healthy ACL knee.
Material and Method: The SRD was applied to 24 ACL-tear knees that were diagnosed by MRI as having complete ACL
tears, and 24 healthy ACLs from the contralateral knee of each patient. Each knee was tested under a force 120 Newtons
in a posterior to anterior direction to create anterior tibial translation at 20 degrees knee flexion. Side-to-side difference
of anterior tibial translation (mm) was measured from radiographs.
Results : We studied 24 patients who had one knee with complete rupture of ACL diagnosed by MRI and the other with
healthy ACL confirmed by clinical diagnosis. The mean anterior tibial translation before and after using the device was
significantly lower in the healthy ACL group than in the ruptured ACL group. A stress radiographic device was used with
a 4 mm side-to-side cut off point of difference of anterior tibial translation between pre- and post-stress displacement for
diagnosis of complete rupture of anterior cruciate ligament. The sensitivity was 79% and specificity was 100%.
Conclusion : The new stress radiographic device is reliable and reproducible in diagnosis of complete rupture of anterior
cruciate ligament.
Keywords : Anterior cruciate ligament tears, Anterior tibial translation, Stress radiographic device
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