Can Weightbearing Cone-beam CT Reliably Differentiate Between Stable and Unstable Syndesmotic Ankle Injuries? A Systematic Review and Meta-analysis

Abstract

BackgroundAnkle injuries are common presentations to the emergency department and may lead to syndesmotic instability. These have a high socioeconomic burden due to prolonged rehabilitation, chronic pain, and posttraumatic arthritis. Early diagnosis is essential to minimize these complications, and the assessment of instability in the clinical setting is often limited by pain and clinician experience. Cross-sectional imaging of the distal syndesmosis accurately evaluates the syndesmosis through abnormal bony relationships, which in the presence of instability, worsens during physiological loading. Cone-beam CT (CBCT) has gained popularity in the diagnosis of these injuries because it enables syndesmotic assessment under weightbearing conditions, it mitigates the high radiation dose, and it is time-efficient.Questions/purposesThe purposes of this systematic review were: (1) to establish normal values for weightbearing CBCT of the syndesmosis in uninjured ankles and ascertain interobserver reliability and (2) to identify the impact of weightbearing on the syndesmosis in patients with occult ankle injuries and assess the effect of patient demographics on these metrics.MethodsThis systematic review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in PROSPERO (ID CRD42021248623). MEDLINE, PubMed, Embase, and Emcare databases were searched for studies assessing for syndesmotic instability, of which 307 studies were screened and 11 studies with 559 ankles in 408 uninjured patients and 151 patients with syndesmotic instability were included. All patients 18 years of age or older presenting with unilateral ankle injuries who underwent weightbearing CBCT for the diagnosis of an occult fracture or syndesmotic instability compared with the uninjured contralateral side were included. A control group of uninjured ankles was identified during weightbearing CBCT performed for other indications such as forefoot or midfoot injuries. Methodological assessment of the studies was performed using the Risk of Bias In Non-randomized Studies (ROBINS-1) tool and most included studies had a low risk of bias. Thus, a random-effects restricted maximum likelihood ratio model was used.ResultsIn the uninjured ankle, the mean area of the tibiofibular syndesmosis was 112.5 ± 7.1 mm2, which increased to 157.5 ± 9.6 mm2 after injury when compared with uninjured ankles with a standardized mean difference of 29.5 (95% confidence interval 19.5 to 39.5; p < 0.01), and an excellent interobserver agreement (κ = 1.0 [95% CI 0.9 to 1.0]). However, syndesmosis volume decreased with age (β = -0.76; p = 0.04), and therefore, has a negative association with increasing age.ConclusionOur study has shown that the syndesmotic area is the most reliable parameter in the assessment of syndesmotic injuries because it increases in the presence of instability during weightbearing status. It is a composite measurement that could potentially allow clinicians to use weightbearin...

Effect of weightbearing and foot positioning on 3D distal tibiofibular joint parameters

“…Such a minor influence of loading was also reported in a recent human cadaveric study designed with different severities of syndesmotic injury 30 . In contrast, a meta analysis could demonstrate that imaging under loading can relevantly support detection of syndesmotic injury when the syndesmotic region is examined in detail 38 . These contradictory findings confirm that further investigations focusing on well-selected parameters of interest are necessary.…”

Ankle syndesmotic instability assessment using a three-dimensional distance mapping algorithm: a cadaveric pilot WBCT study

“…Weight bearing computed tomography (WBCT) has emerged as a promising diagnostic tool that can assess the ankle joint under physiological weight-bearing load, potentially allowing detection of these small deviations of an unstable syndesmosis (2)(3)(4)(5) . This weight load in isolation has been shown to not induce enough stress to reliably demonstrate syndesmotic instability (6,7) , with a better diagnostic accuracy being observed when an external rotational torque is applied in combination (8,9) .…”

Letter to the Editor: Can Weightbearing Cone-beam CT Reliably Differentiate Between Stable and Unstable Syndesmotic Ankle Injuries? A Systematic Review and Meta-analysis

“…For WBCT, Raheman et al [15] concluded that the “syndesmotic area is the most reliable parameter” and “has the potential of being diagnostic of syndesmotic instability.” While systematic reviews and meta-analyses are powerful tools for the cumulative interpretation of studies, the informative value of these research methods depends on a sufficient comparability between the individual studies included. For syndesmotic injuries, the parameters controlled should include a comparable patient sample (differentiation of fracture cases, acute/chronic injuries), a “known” degree of instability (for example, assessed by MRI or arthroscopy), the technique on how the WBCT was conducted (ankle neutral/dorsiflexed, internal/external rotation), and where/how the measurements were performed.…”

“…For WBCT, Raheman et al [15] concluded that the "syndesmotic area is the most reliable parameter" and "has the potential of being diagnostic of syndesmotic instability." While systematic reviews and meta-analyses are powerful tools for the cumulative interpretation of studies, the informative value of these research methods depends on a sufficient comparability between the individual studies included.…”

“…It is noninvasive, dynamic, and can be performed bilaterally. Similar to the abovementioned diagnostics, studies have failed to define normal values for the intact syndesmosis for WBCT [15]. In the largest systematic review to date, Patel et al [14] reported an eightfold difference across values defined as "normal"-making such definitions hard to use in practice.…”