• Venous thromboembolism (VTE) is a serious complication during and after hospitalization, yet is a preventable cause of in-hospital death.

• Without VTE prophylaxis, the overall VTE incidence in medical and general surgery hospitalized patients is in the range of 10% to 40%, while it ranges up to 40% to 60% in major orthopaedic surgery. With routine VTE prophylaxis, fatal pulmonary embolism is uncommon in orthopaedic patients and the rates of symptomatic VTE within three months are in the range of 1.3% to 10%.

• VTE prophylaxis methods are divided into mechanical and pharmacological. The former include mobilization, graduated compression stockings, intermittent pneumatic compression device and venous foot pumps; the latter include aspirin, unfractionated heparin, low molecular weight heparin (LMWH), adjusted dose vitamin K antagonists, synthetic pentasaccharid factor Xa inhibitor (fondaparinux) and newer oral anticoagulants. LMWH seems to be more efficient overall compared with the other available agents. We remain sceptical about the use of aspirin as a sole method of prophylaxis in total hip and knee replacement and hip fracture surgery, while controversy still exists regarding the use of VTE prophylaxis in knee arthroscopy, lower leg injuries and upper extremity surgery.

Cite this article: EFORT Open Rev 2018;3:130-142. DOI: 10.1302/2058-5241.3.170018

• Non-Langerhans cell histiocytosis (N-LCH) summarizes a group of rare diseases with different clinical presentations, pathogenesis and morphology. These include primary cutaneous N-LCH, cutaneous N-LCH with systemic involvement, and primary extracutaneous systemic forms with occasional cutaneous involvement.

• The juvenile (JXG) and non-juvenile xanthogranuloma (N-JXG) family of histiocytoses are N-LCH: the JXG family consisting of the JXG (cutaneous), xanthoma disseminatum (cutaneous and systemic) and Erdheim-Chester disease (ECD; systemic); and the N-JXG family consisting of the solitary reticulohistiocytoma (cutaneous), multicentric reticulohistiocytosis (cutaneous and systemic) and Rosai-Dorfman disease (RDD; systemic).

• ECD is a clonal disorder from the JXG family of N-LCH; RDD is a reactive proliferative entity from the non-juvenile xanthogranuloma family of N-LCH.

• ECD and RDD N-LCH are rare disorders, which are difficult to diagnose, with multi-organ involvement including bone and systemic symptoms, and which respond to therapy in an unpredictable way.

• The key to successful therapy is accurate identification at tissue level and appropriate staging. Patients should be observed and monitored in a long-term pattern. Prognosis depends on disease extent and the organs involved; it is generally good for RDD disease and variable for ECD.

Cite this article: EFORT Open Rev 2018;3:381-390. DOI: 10.1302/2058-5241.3.170047