Post-thrombotic syndrome after total hip or knee arthroplasty: incidence in patients with asymptomatic deep venous thrombosis.

PURPOSE: To measure the risk of developing signs of post-thrombotic syndrome 15 to 24 months after total hip or knee arthroplasty in patients with asymptomatic deep venous thrombosis (DVT).
METHODS: A total of 85 total knee arthroplasty patients and 47 total hip arthroplasty patients were postoperatively screened for asymptomatic DVT using colour duplex ultrasound.
RESULTS: The rate of asymptomatic DVT was 37.6% (n = 32) in knee patients and 34.0% (n = 16) in hip patients. All 32 DVT cases in the knee group had thrombi located below the knee, whereas 6 of the 16 DVT cases in the hip group had thrombi located above the knee, the remaining 10 were below the knee. Patients with proximal thrombi were treated with warfarin for 3 months, whereas patients with distal DVT received 300 mg aspirin daily for the same period. All DVT cases were monitored for up to 12 weeks using repeated colour duplex scans. Signs of thrombus resolution were present at around 6 weeks (range, 4-12 weeks). Clot propagation was observed in 3 cases. In a mean of postoperative 18 months (range, 15-24 months), 28 of the 32 knee patients with asymptomatic DVT were available for follow-up: 11 had transient calf and ankle swelling, 6 had persistent oedema, and the remaining 11 were symptom free. 14 of the 16 hip patients with asymptomatic DVT were available for follow-up: 6 had transient calf and ankle swelling, 4 had persistent oedema, and 4 remained symptom free. 17 patients reported ongoing problems and were re-examined. Signs of mild-to-moderate post-thrombotic syndrome were recorded in 4 knee patients and 3 hip patients.
CONCLUSIONS: Patients with above-knee DVT were much more likely to have post-thrombotic syndrome. Despite thromboprophylaxis with low-molecular-weight heparin, asymptomatic DVT is common after total joint arthroplasty and is responsible for the development of post-thrombotic venous insufficiency and post-thrombotic syndrome in a considerable proportion of patients. Once symptomatic or asymptomatic DVT is established, treatment appears incapable of preventing the occurrence of post-thrombotic syndrome, especially in cases of above-knee DVT. Efforts should hence concentrate on combating DVT propagation and improving DVT prevention.