A systematic review and meta-analysis on the value of the external rotation stress test under fluoroscopy to detect syndesmotic injuries

Abstract

Purpose The aim was to conduct a systematic literature review and meta-anaylsis to analyze the diagnostic accuracy of the external rotation stress test (ERST) for syndesmotic injuries. Methods The systematic review was conducted according to the PRISMA-P guidelines (Prospero ID: CRD42021282457). Four common databases were searched from inception to September 29, 2021. Eligible were any studies facilitating the ERST under fluoroscopy in a defined state of syndesmotic instability. Syndesmotic ligament-specific rupture must have been proven by MRI, arthroscopy, or controlled dissection (cadaver study). Two reviewers independently conducted each step of the systematic literature review. The risk of bias was assessed by the Quality Appraisal for Cadaveric Studies Score scale. The data analysis was performed qualitatively and quantitatively. Results Eight studies were eligible for a qualitative analysis, and six studies were eligible for a quantitative analysis. All studies included were cadaver studies. The qualitative analysis comprised 94 specimens and revealed considerable heterogeneity. Six studies allowed for a quantitative analysis of the tibiofibular clear space (TFCS) and five studies for the medial clear space (MCS) during the ERST. The quantitative analysis of the TFCS revealed no significant differences between intact and any stage of syndesmotic injury. The MCS was able to differentiate between intact and 2-ligament- (Z = 2.04, P = 0.02), 3-ligament- (Z = 3.2, P = 0.001), and 3-ligament + deltoid ruptures (Z = 3.35, P < 0.001). Conclusion The ERST is the only noninvasive test to assess syndesmotic instability and can be conducted bilaterally. The uninjured contralateral side can serve as a baseline reference. Based on the conducted quantitative analysis, the MCS seems to be able to differentiate between stable (intact/1-ligament) and unstable (2-ligament/3-ligament) lesions.

A systematic review of studies on the diagnostics and classification system used in surgically treated, acute, isolated, unstable syndesmotic injury: a plea for uniform definition of syndesmotic injuries

“…This was surprising, as this test is the working horse to assess syndesmotic stability in ankle fracture cases ( 42 , 43 , 44 ). Moreover, a just recently published systematic review assessed the value of the ERST under fluoroscopy to detect subtle syndesmotic instability ( 45 ). Based on the ERST under fluoroscopy, the MCS was capable of differentiating between intact, two-ligament (AiTFL + IOL), three-ligament (AiTFL + IOL + PiTFL), and three-ligament + deltoid ruptures.…”

Syndesmosenverletzungen

“…Ein knöcherner Ausriss der hinteren Syndesmose an der posterioren Tibiakante wird als posteriores malleoläres Fragment (PMF) oder Hinterkantenfragment bezeichnet, im deutschsprachigen Raum häufig als Volkmann-Fragment. 1-Band-und instabilen 2-bis 3-Band-Verletzung dienen [22].…”

“…Dieses Fragment erlangte in den letzten Jahren zunehmend an Bedeutung in der Versorgung von Sprunggelenkfrakturen und Instabilitäten der Syndesmose. Basierend auf deren computertomografischer Diagnostik sind Klassifikationssysteme in Abhängigkeit von der Beteilung der tibiofibularen Inzisur nach Bartonicek et 1-Band-und instabilen 2-bis 3-Band-Verletzung dienen [22].…”

Objective Assessment of Syndesmosis Stability Using the Hook Test

“…Analogous to the hook test, a widening of the syndesmosis is recorded at the moment the force is applied. In this context, it has also been shown that the assessment of a possible widening of the medial clear space seems to be advantageous [11]. If the medial clear space is used in the intraoperative application of stress tests for the assessment of syndesmal instability, the external rotation stress test seems to be superior to the Hook test [12].…”