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Three Part Question

In [patients with knee injuries requiring immobilisation in a cricket pad splint] does [prophylactic anticoagulation with LMWH] reduce the risk of [venous thromboembolic disease over the subsequent three months].

Clinical Scenario

A 23 year old male presents to the emergency department with a knee injury sustained whilst playing football. You diagnose a probable anterior cruciate tear and decide to immobilise the patient in a cricket pad splint. He has a family history of deep vein thrombosis. He is partially weight bearing.
You wonder whether the splint will increase his risk of a venous thromboembolic (VTE) event and in particular whether there is any potential benefit from the use of thromboprophylaxis.

Search Strategy

MEDLINE and EMBASE databases were searched, using the OVID interface, the week ending the 24th June 2011.

MEDLINE: (exp venous thrombosis OR exp thromboembolism OR exp pulmonary embolism OR DVT.mp OR deep vein thrombosis.mp OR PE.mp OR pulmonary embolism.mp OR venous thromb$.mp) AND (exp splint OR splints.mp OR cricket pad splint.mp OR exp immobilization OR immobilisation.mp)

EMBASE: (exp vein thrombosis OR exp thromboembolism OR exp lung embolism OR exp venous thromboembolism OR exp deep vein thrombosis OR DVT.mp OR deep vein thrombosis.mp OR PE.mp OR pulmonary embolism. mp OR venous thromb$.mp) AND (exp splint OR splints.mp OR cricket pad splint.mp OR exp immobilzation OR immobilisation.mp)

Both searches were limited to human studies only.
401 and 1221 records were found in the MEDLINE and EMBASE searches respectively. None of these were felt to be directly relevant to the search question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses

Comment(s)

No trials investigating the relationship between VTE and immobilising splints exist. One study by Lassen et al [1] does include patients treated with ‘braces’. However, the authors do not specify the type of brace used, the numbers included are small (39 and 28) and there is no pre-specified subgroup analysis performed on this cohort. There is evidence that lower limb injuries alone, regardless of the type of immobilisation, increase VTE risk [2]. With more proximal injuries giving the greatest increase in risk one could make a logical argument for giving thromboprophylaxis in certain situations. However, with an absence of evidence demonstrating a benefit sufficient to outweigh the bleeding risk, this cannot be recommended routinely.

Clinical Bottom Line

Routine thromboprophylaxis should not be given to partially weight bearing patients with knee injuries immobilised in splints.

References

1. Lassen M R et al Use of the Low-Molecular-Weight Heparin Reviparin to Prevent Deep-Vein Thrombosis after Leg Injury Requiring Immobilisation NEJM 2002; 347(10): 726 - 730
2. Van Stralen K J et al Minor Injuries as a Risk Factor for Venous Thrombosis Arch Intern Med 2008; 168(1): 21 - 26