Deep Vein Thrombosis in Foot and Ankle Practice                    

 

Introduction

Debate continues on the perceived incidence of deep vein thrombosis (DVT) after foot and ankle surgery and the role of prophylaxis. This is partly because there is a discrepancy in the literature in the definition of what constitutes a deep vein thrombosis: symptomatic / asymptomatic and particularly the distinction between distal (calf) or proximal (thigh) DVTs.

Calf DVTs are only detected if a whole leg ultrasound scan is performed. On the other hand, many radiology departments follow the NICE Clinical Guideline 144 of 2012 (updated to CG158 in 2020) to only scan and report on proximal DVTs, because whole leg ultrasound is time consuming and technically demanding. Calf DVTs only very rarely cause pulmonary emboli and are therefore not usually treated by anticoagulation. However, about 30% of calf DVTs can propagate to become proximal DVTs in about a week and CG 158 states that proximal leg ultrasound, if negative, should be repeated in 6-8 days in those with raised D-dimers (=most orthopaedic patients).

DVTs after orthopaedic surgery may therefore be under-diagnosed and underreported.

Patel et al. retrospectively reviewed a large US healthcare management database:

  • 1172 patients with Achilles tendon ruptures
  • reported incidence of 0.43% of symptomatic DVTs

Scandinavian studies of Achilles tendon ruptures:

  • detailed sonographic study of the whole leg
  • 32% rate of symptomatic and asymptomatic DVT

However, Nilson-Helander et al looked at these figures more closely:

  • of these 32 reported DVTs per 100 TA rupture patients
    • 27 were calf DVTs
    • 5 were thigh DVTs

The reported rate in the UK would thus be 5% and not the reported 32% rate in the study. Some clinicians thus perceive the incidence of DVT after Achilles tendon rupture to be high.

It is suggested that all studies and guidelines on prophylaxis should clearly state whether calf DVTs are being considered.

 

Prophylaxis

The NICE guidelines NG89 on lower limb casts / F&A surgery:

  • Consider pharmacological VTE prophylaxis with LMWH or fondaparinux for people with lower limb immobilisation OR
  • When total anaesthesia time is >90 mins OR
  • The person’s risk of VTE outweighs their risk of bleeding
  • Consider stopping prophylaxis if immobilisation >42 days

BOFAS Round Table meeting in 2012 unanimous consensus:

  • patients should undergo risk assessment for DVT for elective surgery
  • immobilisation and NWB status were highlighted as a significant risk factor

Survey of UK F&A surgeons in 2014 regarding the use of LMWH prophylaxis when in a NWB cast:

  • 70% use prophylaxis after a triple fusion
  • 80% use prophylaxis for Achilles tendon ruptures
  • 100% use prophylaxis after ankle fracture if there is an additional risk factor
  • Only 15% of F&A Surgeons would use prophylaxis in ankle fractures when in a WB cast, if no additional risk factors

 

Investigations

A clinician relies on the non-specific symptoms and signs of a DVT to consider further investigation. Whilst venography may remain the gold standard, USS remains the most practical and widely available. D-dimer is of questionable use in the post-operative / trauma period as it will usually be raised.

UK practice 2014: how to investigate if clinically suspicious for DVT

  • 75% would refer for a duplex doppler USS
  • 50% of UK hospitals have a specific protocol
  • If suspicion remained – and the first scan was negative – 80% would re-refer for another USS
  • 65% would prefer to ask for an USS of the whole leg
  • 15% would measure the D-dimer

NICE Guidance CG158 (2020):

  • If Wells score ≥2:
    • Immediate proximal leg vein ultrasound OR:
      • obtain D-dimer
      • offer interim therapeutic anticoagulation
      • obtain proximal leg vein ultrasound within 24 hours
  • If scan positive: offer anticoagulant treatment
  • If scan negative but positive D-dimer: stop anticoagulation, repeat scan in 6-8 days
  • If scan negative and negative D-dimer: stop anticoagulation, consider alternatives

 

Treatment of DVT

UK practice 2014: Treatment of a symptomatic proximal DVT

  • 3 months’ anticoagulation if time-limited risk factor i.e. cast / immobilisation
  • 6 months’ anticoagulation if risk factor isn’t time-limited
  • Recurrent DVT or malignancy, consider anticoagulation for >12 months or lifetime

UK practice 2014: Treatment of a symptomatic distal DVT

  • 30% would anticoagulate
  • 10% would not anticoagulate
  • 60% did not know and would consult DVT service / haematologists

NICE Guidance CG158 (2020):

  • Offer apixaban or rivaroxaban treatment for ≥ 3 months in confirmed proximal DVT or PE
  • Adjust dose in renal impairment, extremes of body weight
  • Consider longer treatment in unprovoked DVT or active cancer

 

References

Venous thromboembolic diseases: diagnosis, management and thrombophilia testing.  NICE Clinical Guidelines (NG158). March 2020.

Patel A, Ogawa B, Charlton T, Thordarson D.  Incidence of deep vein thrombosis and pulmonary embolism after Achilles tendon rupture.  Clin Orthop Relat Res 470:270-274,2012.

Nilsson-Helander K, Thurin A, Karlsson J, Eriksson BI. High incidence of deep vein thrombosis after Achilles tendon rupture: a prospective study. Knee Surg Sports Traumatol Arthrosc 2009.

Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism. NICE guideline (NG89). March 2018 (updated Aug 2019).