Warwick_edit.qxp 28/9/07 12:45 Page 48
Orthopaedic Surgery
Deep Vein Thrombosis Prophylaxis in Orthopaedic Surgery
a report by
David Warwick
Consultant Orthopaedic Surgeon, Southampton University Hospitals NHS Trust
Despite a huge literature base, thromboprophylaxis in orthopaedics hours of each other. The interval for pentasaccharides, with their longer
remains controversial. The scale of the problem is disputed and the half-life, is likely to be much longer.
cost–benefit and risk–benefit ratios, and the practicality of any particular
protocol, are uncertain. Surgical Technique
A rough surgical technique may potentiate thromboplastin release.
What Is the Scale of the Problem? Prolonged torsion of the dislocated hip while reaming, or aggressive
Some orthopaedic procedures, such as upper limb surgery, probably carry dorsal retraction of the tibia, causes two problems: first, the adjacent
minimal risk of thrombosis, while others, such as revision hip surgery or deep veins may be damaged; and second, by blocking venous return, the
complex lower limb trauma reconstruction, probably carry a particularly calf veins are distended, exposing subendothelial collagen and thus
high risk.
1,2
Asymptomatic deep vein thrombosis (DVT) occurs in 58% of initiating thrombosis.
major trauma patients, 3–18% of knee arthroscopy patients and
10–35% of patients with isolated lower limb injuries. Without Tourniquet
prophylaxis, the death rate from pulmonary embolism (PE) after hip There is no evidence that tourniquet use aggravates thrombogenesis. The
replacement or knee replacement is probably around 0.4%, and perhaps accumulation of clotting factors while the tourniquet is inflated is
slightly higher after hip fracture. With 1.2 million arthroplasties per year probably balanced by the fibrinolytic and valve-flushing hyperaemia on
in Europe, that equates to 4,800 deaths – a huge problem. About 3–4% tourniquet deflation.
will develop a symptomatic DVT or PE requiring treatment, which is the
most common avoidable complication and the most common reason for Mechanical Prophylaxis
re-admission. The frequency of chronic venous insufficiency, an
important longer-term outcome, is unknown. Graduated Compression Stockings
These are commonly used. To work, they must be properly woven and
Does Prophylaxis Work? well-fitted and remain in place. The evidence on their efficacy after
The event rates listed above can be reduced with careful prophylaxis. orthopaedic surgery is weak, but a meta-analysis of other surgical studies
Historically, almost all prophylaxis studies relied on radiological suggests a modest benefit.
8–12
surrogates;
3
more recently, a reduction in radiological thrombosis using
extended-duration chemical prophylaxis has been shown to correlate Intermittent Pneumatic Compression Devices
with a reduction in symptomatic events. No study could be large enough These devices enhance both deep venous flow and fibrinolysis. The peak
to directly show a reduction in fatal PE, but it is biologically plausible that venous flow varies with different devices depending on the frequency of
a reduced DVT frequency translates to a reduced fatal PE rate. Most contractions, the number of compartments, above- or below-knee design
studies refer to hip and knee arthroplasty patients; there are far fewer and inflation pressure. The ideal parameters have not been established;
data on other orthopaedic procedures. however, in general these devices are effective.
13–21
What Prophylaxis Should Be Used? Foot Pumps
There are three categories of prophylaxis: general, mechanical and chemical. These rhythmically empty the venous plexus in the sole of the foot,
flushing out the deep leg veins and providing prophylaxis that is probably
General Measures equivalent to LMWH in hip arthroplasty. The evidence after knee
arthroplasty is less convincing. The efficacy of foot pumps depends on
Early Mobilisation factors such as the pressure and frequency of the impulses and the ability
There is a good physiological premise, although only weak circumstantial of the leg to produce pre-load.
22–40
evidence, that early mobilisation reduces thromboembolism.
Advantages of Mechanical Prophylaxis
Neuraxial Anaesthesia These methods do not carry a risk of bleeding, which is intrinsic to
This reduces mortality and enhances peri-operative analgesia. The DVT chemical methods. This is enticing to surgeons and anaesthetists, who
rate is reduced by about one-third.
4–7
There are concerns about have to balance risk and benefit, particularly in the peri-operative period.
concomitant use of chemical prophylaxis and neuraxial anaesthesia, lest
a spinal haematoma develop. It is prudent to avoid giving neuraxial Drawbacks of Mechanical Prophylaxis
anaesthesia and low-molecular-weight heparin (LMWH) within at least six All mechanical methods have the disadvantages of expense and
48 © TOUCH BRIEFINGS 2007
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99