Thromboprophylaxis are routinely given to prevent venous thromboembolism (VTE) in patients after total hip and knee replacement surgeries. Low molecular weight heparin (LMWH) (fractioned heparin) is effective in the prevention and treatment of VTE. The predicable effect of LMWH has popularized it for routine clinical use. Although LMWH has lesser complication rate, compared to unfractioned heparin (UFH), sporadic clinical complication has been reported. We report a rare case of skin necrosis secondary to use of LMWH tinzaparin used for routine thromboprophylaxis after total knee replacement. 1. Introduction Low molecular weight heparin (LMWH) was developed in the late 1970s after the elucidation of heparin’s structure and the identification of the pentasaccharide as being its minimal active fragment. LMWHs have proven to be well tolerated and effective in the prevention and treatment of venous thromboembolism (VTE). The advantages of LMWHs include its predictable anticoagulant response, an improved bioavailability, and a longer half-life [1] which have replaced the traditional use of unfractioned heparin (UFH) to prevent VTE in patients undergoing total hip and knee replacement surgeries [2, 3]. Adverse effects of LMWHs are also quite uncommon making it advantageous compared to unfractioned heparin, probably because of the smaller size of the molecules, the greater homogeneity of the substance, and the exclusive porcine origin of the new compounds. Skin reactions, a recognised complication of heparin products, have been reported with the use of UFH. However, there are only a few reports of LMWH causing skin reactions. We report a rare case of skin necrosis secondary to the use of LMWH Tinzaparin. 2. Case Report A 67-year-old female patient, of BMI 30, suffering from severe osteoarthritis of her knee, underwent an elective total knee replacement surgery. She did not have any significant past medical history and had a normal blood profile prior to surgery. There were no intraoperative complications or immediate postoperative complications. As a routine postoperative care, she was administered prophylactic subcutaneous tinzaparin (low molecular weight heparin) 3,500？IU once a day on her abdomen. On postoperative day 14, she developed an area of erythema associated with pain at the sites of her LMWH injection (Figure 1). Blood investigation revealed a normal platelet count of 254 (normal range 143–332 × 109) with Haemoglobin of 12.5 (normal range 3.9–15 × 109) and WCC 10.5 (normal range 3.9–11.1 × 109). Figure 1: Skin necrosis on anterior abdominal wall
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