[The complete dislocation of the talus or «missing talus¼.] / L'image du mois. Dislocation complète du talus ou «missing talus¼.

The complete dislocation of the talus or «missing talus¼ corresponds to a simultaneous dislocation of the tibiotalar, talocalcaneal and talonavicular joints, without associated talar fracture. This lesion occurs as part of high energy trauma and accounts for 3 to 5 % of talus injuries. It is most frequently anterolateral and in more than 75 % of cases, this dislocation is open. Among the soft tissue lesions that are often associated with the dislocation, vascular lesions leading to avascular necrosis of the talus are found in almost 100 % of cases. This necrosis is generally well tolerated by the patient. A conservative treatment by reimplantation of the talus after debridement of the site should be performed as a first-line treatment as fast as possible. When the avascular necrosis of the talus is not well tolerated by the patient, a talectomy associated with tibiocalcaneal arthrodesis can be performed as a secondary procedure. Talectomy alone should not be done.

La dislocation complète du talus ou «missing talus¼ correspond à une dislocation simultanée des articulations tibiotalienne, talocalcanéenne et talonaviculaire, sans fracture talienne associée. Cette lésion survient dans le cadre d'un traumatisme à haute énergie et représente 3 à 5 % des lésions du talus. Elle est le plus fréquemment antéro-latérale et, dans plus de 75 % des cas, cette dislocation est ouverte. Parmi les lésions des tissus mous qui y sont souvent associées, les lésions vasculaires conduisant à une nécrose avasculaire du talus sont retrouvées dans presque 100 % des cas. Cette nécrose est généralement bien tolérée par le patient. Un traitement conservateur par réimplantation du talus après débridement du site doit être réalisé en première intention et ce, de manière urgente. Lorsque la nécrose avasculaire du talus n'est pas bien tolérée par le patient sur le long terme, une talectomie associée à une arthrodèse tibio-calcannénne peut être réalisée dans un second temps. La talectomie seule doit, quant à elle, être proscrite.

Trapeziometacarpal total joint replacement as an alternative to trapeziectomy depends on trapezium height: Retrospective study of 67 patients.

Surgical indications for trapeziometacarpal (TMC) total joint replacement for thumb basal joint osteoarthritis (OA) are increasing. However, complications following this procedure are not insignificant. To avoid complications, preoperative planning with measurement of trapezium height is indicated to ensure a cup is not implanted in the trapezium if its height is less than 8 millimeters. The objective of our study was to analyze a series of preoperative radiographs of patients managed by trapeziectomy and suspensionplasty in our department, and to assess the possibility of a surgical alternative-total joint replacement-based on the trapezium's height. We also wanted to determine whether radiological height was influenced by the radiological progression of the thumb OA. A single-center retrospective study based on available medical records was conducted. The patients included had TMC OA refractory to conservative treatment and were managed surgically by trapeziectomy and suspensionplasty between 2012 and 2018. Sixty-seven patients were eligible. Based on the Eaton-Littler classification of radiological TMC OA, our case series had 0% (n=0) stage I, 36% (n=24) stage II, 42% (n=28) stage III and 22% (n=15) stage IV findings. We measured the radiological trapezium height on AP and lateral views as described by Kapandji. These were 10.6mm and 10.8mm for stage II, 9.6mm and 8.9mm for stage III, 8.6mm and 7.8mm for stage IV, respectively. Eighty-six percent of patients had a trapezium height suitable for total joint replacement. The radiological height decreased significantly with the OA stage. At stage IV, the average height fell below the 8-mm threshold, compromising the surgical indication for total arthroplasty.