Stress radiography for the diagnosis of knee ligament injuries: a systematic review.

BACKGROUND: Stress radiography is a widely used diagnostic tool to assess injury to the anterior and posterior cruciate ligaments and the medial and lateral structures of the knee. However, to date, numerous techniques have been reported in the literature with no clear consensus as to which methodology is best for assessing ligament stability.

QUESTIONS/PURPOSES: The purpose of this review was to identify which stress radiographic techniques have support in the literature for the diagnosis of acute or chronic knee ligament injuries, to define which technique is most accurate and reliable for diagnosing knee ligament injuries, and to compare the use of stress radiography with other diagnostic tests.

METHODS: Two independent reviewers performed a systematic review of PubMed (MEDLINE), the EMBASE library, and the Cochrane Controlled Trials Register for English language studies published from January 1970 to August 2013 on the diagnosis of knee ligament injuries using stress radiography. Information describing the ligament(s) investigated, stress radiographic technique, magnitude of force, measures of accuracy and reliability, and comparative diagnostic tests were extracted. Risk of bias was assessed using the QUADAS-2 tool.

RESULTS: A total of 16 stress techniques were described for stress radiography of the knee. The diagnostic accuracy of stress radiography including the sensitivity, specificity, and positive and negative predictive values varied considerably depending on the technique and choice of displacement or gapping threshold. Excellent reliability was reported for the diagnosis of anterior cruciate ligament, posterior cruciate ligament, varus, and valgus knee injuries. Inconsistencies were found across studies regarding the efficacy of stress radiography compared with other diagnostic modalities.

CONCLUSIONS: Based on the multitude of stress techniques reported, varying levels of diagnostic accuracy, and inconsistencies regarding comparative efficacy of stress radiography to other diagnostic modalities, we are not able to make specific recommendations with regard to the best stress radiography technique for the diagnosis of knee ligament injuries. Additional comparative studies using consistent methodology and appropriate blinding are necessary to further define differences in accuracy and reliability both among stress radiography techniques and between stress radiography and other diagnostic tests.

LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.