Incidence, Natural History and Risk Factors of Deep Vein Thrombosis in Elective Knee Arthroscopy
K. T. Delis(1, 3), N. Hunt(2, 3), R. K. Strachan(2, 3), A. N. Nicolaides(1)
Departments of Vascular Surgery(1, 3) and Orthopaedics(2, 3), St Mary’s Hospital1, Charing Cross Hospital(2) and Ealing Hospital(3), Imperial College School of Medicine, London, UK
Aims: to determine the incidence, anatomical distribution and extent
of deep vein thrombosis (DVT) in limbs undergoing elective unilateral
knee arthroscopy without active prophylaxis, to evaluate its effect on
venous function following early diagnosis, and to quantify the impact
of risk factors on its incidence.
Methods: 102 consecutive patients undergoing unilateral knee
arthroscopy without prophylaxis were studied. A history was obtained
with emphasis on the risk factors for thromboembolism, and physical
examination and colour duplex were performed prior to and within a
week after surgery. Patients who developed calf DVT were given
aspirin (150 mg) and compression stockings; those with proximal DVT
were admitted for anticoagulation (heparin followed by warfarin).
Follow-up (mean 118 [range 84-168] days) entailed weekly physical
and duplex examinations during the first month and monthly thereafter.
Results: 8 patients developed calf DVT in the operated leg (incidence
7.84% [95% Cl: 2.7%-13.2%]); thrombosis was asymptomatic in
4 of those (50%), caused calf tenderness in 4 (50%) and a positive
Homan’s sign in one (12.5%). DVT occurred in the following veins:
peroneal 4 subjects (50%), soleal 4 (50%), gastrocnemial 2 (25%) and
tibial 2 (25%). Propagation of a calf DVT to the popliteal vein was
identified in 1 patient (12.5%). After a median period of 118 days, total
clot lysis was found in 50% of DVTs, with partial thrombus resorption
in the rest; reflux in the thrombosed veins was present in 75% of limbs
with DVT. 43% of patients had 1 risk factor for DVT and 20% had =2.
The incidence of DVT was higher amongst those with two or more risk
factors for thromboembolism (p <.05) or those with previous thrombosis
alone (p <.005). Symptoms or signs of pulmonary embolism
were not documented.
Conclusions: Elective unilateral knee arthroscopy performed
without prophylaxis is complicated by ipsilateral calf DVT in 7.8%
(95% CI: 2.7%-13.2%) of cases. The risk is higher in the presence of
previous thrombosis (relative risk: 8.2) and two or more risk factors for
DVT (relative risk: 2.94). Thrombosis may propagate to the proximal
veins, despite early diagnosis. 50% of calf clots totally lyse in 4 months,
yet reflux develops in at least 75% of limbs with DVT. Further studies
to determine optimal prophylaxis are warranted.