Arthroscopic coronal plane syndesmotic instability has been over-diagnosed

Abstract

Purpose Ankle arthroscopy is widely used for diagnosis of syndesmotic instability, especially in subtle cases. To date, no published article has systematically reviewed the literature in aggregate to understand which instability values should be used intraoperatively. The primary aim was to systematically review the amount of tibiofibular displacement that correlates with syndesmotic instability after a high ankle sprain. A secondary aim is to assess the quality of such research. Methods Systematic searches of EMBASE (Ovid) and MEDLINE via PubMed, CINAHL, Web of Science, and Google Scholar were used. Inclusion criteria: studies that arthroscopically evaluated the fibular displacement at various stages of syndesmotic ligament injury. Two reviewers independently extracted data and assessed methodological quality using the Anatomical Quality Assessment (AQUA) Tool and methodological index for non-randomized studies (MINORS). Results Eight cadaveric studies and three clinical studies were included for review. All studies reported displacement in the coronal plane, four studies reported in the sagittal plane, and one reported findings in the rotational plane. Four cadaveric studies had a similar experimental set up and the weighted mean associated with instability in the coronal plane could be calculated and was 2.9 mm at the anterior portion of the distal tibiofibular joint and 3.4 mm at the posterior portion. Syndesmotic instability in the sagittal plane is less extensively studied, however available data from a cadaveric study suggests thresholds of 2.2 mm of posterior fibular translation when performing an anterior to posterior hook test and 2.6 mm of anterior fibular translation when performing a posterior to anterior hook test. Conclusions The results have concluded that the commonly used 2.0 mm threshold value of distal tibiofibular diastasis may lead to overtreatment of syndesmotic instability, and that using threshold values of 2.9 mm measured at the anterior portion of the incisura and 3.4 mm at the posterior portion may represent better cut off values. Given the ready availability of 3 mm probes among standard arthroscopic instrumentation, at the very least surgeons should use 3 mm in lieu of 2 mm probes intraoperatively. Level of evidence IV.

Do Coronal or Sagittal Plane Measurements Have the Highest Accuracy to Arthroscopically Diagnose Syndesmotic Instability?

“…[3][4][5][6]9,10 Notably, a recent systematic review suggested cutoff values of 2.9 mm and 3.4 mm measured at the anterior and posterior portions of the incisura, respectively, to differentiate a stable from an unstable syndesmosis in the coronal plane. 2 Similar to our findings, a clinical study by Ogilvie-Harris et al 8 demonstrated that clinical assessment by the fibular shuck test in the sagittal anterior-to-posterior direction was found to be more applicable to assess syndesmotic joint instability than coronal plane assessment. This can be rationalized by the anatomical consideration that, in the sagittal plane, the fibula has a greater degree of freedom than in the coronal plane, because it can move in the anterior and posterior direction, while in the coronal plane, medial movement of the fibula is constrained by the presence of the tibia.…”

Acute clinical evaluation for syndesmosis injury has high diagnostic value

“…Although physical examination was standardized and clear test instructions were provided, minor variations in the execution might have influenced the reported diagnostic accuracy. Finally, MRI was used as reference standard despite its inability to diagnose syndesmosis instability [ 9 , 13 ].…”

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

“…Previous studies have reported MCS ranging from 2.0 to 4.7 mm ( 34 ) and TFCS values ranging from 2.3 to 4.8 mm ( 34 ) for the intact stressed state on mortise views. This heterogeneity also limits the definition of absolute cut-off values for arthroscopic probing ( 11 ).…”

“…More recently, arthroscopy has been promoted ( 7 ). However, arthroscopy is an invasive, highly demanding technique, and the definition of instability criteria is hindered due to considerable individual anatomical variations ( 11 ).…”