Emerg Med J 29:779-780 doi:10.1136/emermed-2012-201686.5
  • Best Evidence Topic reports

BET 4: Quantifying the risk of venous thromboembolism for temporary lower limb immobilisation in ambulatory patients


A short cut review was carried out to establish whether the risk of a venous thromboembolic event could be quantified for patients with temporary immobilisation of the lower limb after injury. Five papers were directly relevant to the question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. The clinical bottom line is that the incidence of venous thromboembolism following temporary immobilisation for isolated lower limb trauma in ambulatory patients is approximately 11%.

Report by: Rachel Smith, Ellena Wood, Medical Students

Search checked by: Dan Horner, Emergency Medicine Research Fellow

Institution: University of Manchester/Central Manchester NHS Foundation Trust, Manchester, UK

Three-part question

In (non-surgical ambulatory patients with lower limb injury) does (temporary immobilisation) increase the 3-month risk of (venous thromboembolic disease or sudden death).

Clinical scenario

A 30-year-old patient attends your department 2 weeks following a lateral malleolar ankle fracture. They complain of increased pain and cramping up the calf. The toes are swollen but there are no clinical signs of compartment syndrome.

You are concerned about the possibility of deep vein thrombosis and arrange an ultrasound scan to investigate further. A junior doctor asks you what the incidence/pretest probability of venous thromboembolism is within this cohort of immobilised ambulatory patients.

You tell them that is an excellent question, and that you will give them 1 week to find out the answer for you.

Search strategy

MEDLINE was searched using the OVID Interface from 1948 to July week 1 2011. EMBASE was searched using the OVID Interface from 1980 to 2011 week 27. The Cochrane Database of Systematic Reviews was also searched using direct terminology applicable to the three-part question.

(exp IMMOBILIZATION/) OR (exp CASTS, SURGICAL/) OR (exp SPLINTS/) OR (immobilisation.ti,ab) OR ( OR (plaster AND of AND OR (plaster AND of AND paris.ti,ab) OR (plaster AND cast.ti,ab) OR (backslab.ti,ab) OR exp Splints/] AND [(lower AND limb.ti,ab) OR (lower AND OR exp LEG/ OR exp Lower extremity/] AND [(exp VENOUS THROMBOEMBOLISM/) OR (exp THROMBOEMBOLISM/) OR exp Deep Vein Thrombosis/ OR (exp PULMONARY EMBOLISM/) OR (deep AND vein AND OR (pulmonary AND OR (VTE.ti,ab) OR (exp DEATH, SUDDEN)].

Search outcome

One hundred and twenty-four papers were retrieved, of which five were directly relevant to the three-part question (table 3). One systematic review was discounted due to substantial heterogeneity within subjects, inclusion of partly treated patients within the conservative arm and further methodological concerns (Schade and Roukis).

Table 3

Relevant papers


Temporary immobilisation in non-surgical isolated limb trauma within the preceding 2 months has been recently associated with 2% of all venous thromboembolisms (Bertoletti et al). These events can be potentially fatal. Limb immobilisation has also recently been highlighted as provoking the highest risk of venous thromboembolism among all causes of immobilisation (Beam et al). National guidance promotes clear advice regarding thromboprophylaxis in hospital inpatients. There is little advice regarding ambulatory patients seen in the emergency department who are exposed to similar risk. To address the issue properly we must first understand the scale of the problem, by identifying the incidence of disease in order to quantify risk. There are several common issues regarding the majority of studies generating data within the designated cohort. First, the use of venous thromboembolism as an outcome generates controversy: an event can range from an isolated asymptomatic distal deep vein thrombosis to a life-threatening pulmonary embolism. Some would argue that these events have profoundly differing morbidity/mortality rates and as such should not be collated as an outcome. Second, many studies group post-surgical ambulatory together with conservatively treated patients. This can confound the emergency department cohort and should be carefully avoided when addressing epidemiological data through contemporary research.

Clinical bottom line

The incidence of venous thromboembolism following temporary immobilisation for isolated lower limb trauma in ambulatory patients is approximately 11%. This rate can vary in different ambulatory cohorts from 2% to 30%, depending on the type of injury and immobilisation used. Although the majority of these events will be distal deep vein thrombosis, pulmonary emboli do occur in this cohort and contribute to cumulative incidence.

Level of evidence

Level 2—Studies considered were neither 1 nor 3.

▶ Schade VL, Roukis TS. Antithrombotic pharmacologic prophylaxis use during conservative and surgical management of foot and ankle disorders: a systematic review. Clin Podiatr Med Surg 2011;28:571–88.

▶ Bertoletti L, Rhigini M, Bounameaux H, et al; RIETE Investigators. Acute venous thromboembolism after non major orthopaedic surgery or post-traumatic limb immobilisation. Findings from the RIETE registry. Thromb Haemost 2011;105:739–41.

▶ Beam DM, Courtney DM, Kabrehl C, et al. Risk of thromboembolism varies, depending on category of immobility in outpatients. Ann Emerg Med 2009;54:147–52.

▶ Patil S, Gandhi J, Curzon I, et al. Incidence of deep-vein thrombosis in patients with fractures of the ankle treated in a plaster cast. J Bone Joint Surg (Br) 2007;89:1340–3.

▶ Testroote M, Stiger W, de Visser DC, et al. Low molecular weight heparin for prevention of venous thromboembolism in patients with lower-leg immobilization. Cochrane Database Syst Rev 2008;(4):CD006681.

▶ Nilsson-Helander K, Thurin A, Karlsson J, et al. High incidence of deep venous thrombosis after Achilles tendon rupture: a prospective study. Knee Surg Sports Traumatol Arthrosc 2009;17:1234–8.

▶ Healey B, Beasley R, Weatherall M. Venous thromboembolism following prolonged cast immobilisation for injury to the tendo achillis. J Bone Joint Surg Br 2010;92:646–50.

▶ Thomas S, van Kampen M. Should orthopedic outpatients with lower limb casts be given deep vein thrombosis prophylaxis? Clin Appl Thromb Hemost 2011;17:405–7.


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