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.

Purpose Our aim is to retrospectively review and evaluate the patterns of affection of Charcot arthropathy of foot and ankle. Methods Two hundred twenty-eight patients (235 feet) with post-acute Charcot were reviewed and classified anatomically through plain radiographs into type I and type II based on single or multiple regions affected, respectively. Type I included ankle, Lisfranc (tarsometatarsal), naviculocuneiform, forefoot, and hindfoot which includes one of the following: talonavicular joint, calcaneocuboid joint, or calcaneus. Type II included peritalar, perinavicular, mid-tarsal Charcot, or any other combination. Both types were further classified into four stages (A, stable with no deformity; B, stable with deformity; C, unstable; and D, deformity/instability with associated mechanical ulcers). ResultsThe most common type was type IIC (27.2%) followed by type IID (18.3%), while types IA and IIA represented the least common types (3.4% and 3.8%, respectively). Types IA and IIA were managed conservatively. All patients in types IC, ID, IIB, IIC, and IID and the majority of type IB received fusion surgery to achieve stability and correction of deformity. Type II D had the highest complication rate (30%). Five patients ended up with amputation, and all were stage IID. Conclusion Affection of single region has better prognosis than affection of two or more regions. Stage A has the best prognosis and can be managed conservatively provided good diabetes control. Surgery is indicated in all cases of types IC, ID, IIB, IIC, and IID to achieve stability and correction of deformity and prevent complications. Mechanical ulcer (stage D) carries the worst prognosis and highest complication rate.