Deep-vein thrombosis prophylaxis in orthopedic surgery: hip surgery.

Hip replacement surgery carries a high risk of thromboembolic complications, and pharmacological prophylaxis is routinely adopted in clinical practice. Meta-analyses have indicated that low molecular weight heparins (LMWHs) are clinically superior to conventional prophylaxis with unfractionated heparin. These analyses have regarded LMWHs as one chemical entity, despite differences in their physicochemical, biological, and pharmacodynamic properties. Comparing data from trials of different LMWHs is difficult despite standardization in trial design, patient selection criteria, and efficacy assessments, as the influences of concurrent disease and variation in venogram interpretation are difficult to interpret. Furthermore, variations in bleeding assessment limit conclusions on the safety profile of different LMWHs. Two clinical trials have compared enoxaparin with tinzaparin and reviparin respectively. Efficacy equivalence was demonstrated despite differences in the anti-Xa activities of the doses given. These trials support the position of the United States Food and Drug Administration and the World Health Organization that LMWHs are distinct, noninterchangeable compounds and cannot be therapeutically substituted based upon anti-factor Xa levels. The extent of clinical experience with each LMWH is an important factor influencing clinical use.

Clinical limitations of risk assessment models.

Appropriate thromboprophylaxis in hospital patients is effective in preventing clinically important venous thromboembolic events, including deep vein thrombosis (DVT) and fatal pulmonary embolism. Due to the risk of bleeding associated with pharmacological prophylaxis and the cost of administering prophylactic drugs, the clinical benefit and cost-effectiveness of thromboprophylaxis may be optimized by providing prophylaxis only to patients at risk of thrombosis, and tailoring the intensity of prophylaxis to the level of risk. Accurate assessment of patients' thromboembolic risk is therefore highly necessary. Thromboembolic risk is influenced by numerous factors. Several risk factor indices based on clinical risk factors and laboratory variables have been proposed since the 1970s, but these have not been widely adopted due to their complexity and lack of prospective validation. The method of deriving risk data on which these indices are based is questioned, and older prognostic indices excluded recently identified risk factors, particularly molecular factors such as the clotting factor V Leiden mutation, further undermining their clinical value. A number of much simpler risk assessment models (RAMs) have now been developed which stratify patients into low-, moderate- and high-risk categories. However, no RAM currently available provides comprehensive guidance for all patient groups. Use of poorly designed RAMs may fail to identify some patients at risk, leading to omission of prophylaxis and preventable thrombotic events. Certain patient groups develop DVT despite prophylaxis. Current RAMs are not validated to identify these patients. Well-designed and well-validated RAMs, incorporated into standard practice guidelines in hospitals, should contribute to improved clinical outcomes and economic benefits of prophylaxis.

[Ambulatory orthopedic surgery]. / Ambulant ortopaedisk kirurgi.

A one year survey of the patients assessment of out-patient orthopaedic surgery in local anaesthesia is presented. The report is based upon questionnaires (including 15 items) of 529 operations performed on 495 patients. A large group of knee arthroscopies are included. We found that many orthopaedic operations, formerly treated as in-patient procedures could be carried out in the out-patient clinic with only a minimal complication rate. 77% of the patients experienced no problems other than pain in their home following the out-patient surgical procedure. Nearly 80% of the patients would choose out-patient surgery in case of a new identical operation. 30% of the patients found the administration of the local anaesthesia very painful and 41% experienced discomfort and pain following surgery. In addition, a brief analysis of the economical aspect is given. In conclusion, out-patient orthopaedic surgery is well accepted by the patients. The use of local anesthesia alone is not always sufficient and administration of an oral analgesic drug both before and after the surgical procedure is recommended.