Does thromboprophylaxis reduce symptomatic venous thromboembolism in patients with below knee cast treatment for foot and ankle trauma? A systematic review and meta-analysis

Venous Thromboembolism in Foot and Ankle Trauma

Every surgeon may have experienced a tragic event associated with death or debilitation secondary to deep vein thrombosis (DVT) or pulmonary embolism (PE) after foot and ankle trauma and surgery. Nevertheless, the prevention of such a tragic event needs to be carefully evaluated rationally with currently available epidemiologic data. With great postoperative protocols and access to care, most PE events can be prevented. There are modifiable risk factors, such as length/type of immobilization and operative trauma/time that can lower the incidence of DVT/PE. In addition, chemical prophylaxis may be warranted in certain people within the foot and ankle trauma population.

Thromboembolic Events During Weightbearing vs Nonweightbearing Accelerated Rehabilitation Protocols for Complete Achilles Tendon Ruptures

Background

Achilles tendon rupture can be treated nonoperatively with functional rehabilitation. However, prolonged immobilization has associated risk of venous thromboembolism (VTE). Early weightbearing may reduce VTE risk, and this was introduced to our rehabilitation protocol. We investigated the prevalence of symptomatic VTE events before and after the introduction of the early weightbearing protocol.

Methods

Adults with ultrasonography-confirmed complete tendo-Achilles ruptures between January 2017 and June 2020 were included. Preprotocol, patients were instructed to not weightbear for 4 weeks. In 2018, immediate weightbearing was introduced to the treatment protocol. All patients in both cohorts were given low-molecular-weight heparin for 4 weeks. Patients with symptomatic VTE events were investigated with duplex ultrasonographic scan or chest computed tomography. Two independent anonymized examiners collected data from electronic records. Rates of symptomatic VTEs were compared.

Results

A total of 296 patients were included. Sixty-nine patients were managed with the nonweightbearing protocol, and 227 patients were managed with the early-weightbearing protocol. Two patients in each group developed deep vein thrombosis and 1 developed pulmonary embolism in the early-weightbearing group. Rates of VTEs were lower in the early-weightbearing group (1.3% vs 2.9%) but did not reach statistical significance (P = .33).

Conclusion

In this cohort we found that symptomatic VTE after nonoperatively treated Achilles tendon rupture was uncommon. We did not demonstrate a reduction in symptomatic VTE between our early weightbearing and nonweightbearing rehabilitation protocols. We believe a larger study may help clarify whether early weightbearing is beneficial in VTE reduction.

Level of Evidence

Level III, retrospective cohort study.

Prevention of venous thromboembolic events in patients with lower leg immobilization after trauma: Systematic review and network meta-analysis with meta-epsidemiological approach

BACKGROUND

Lower limb trauma requiring immobilization is a significant contributor to overall venous thromboembolism (VTE) burden. The clinical effectiveness of thromboprophylaxis for this indication and the optimal agent strategy are still a matter of debate. Our main objective was to assess the efficacy of pharmacological thromboprophylaxis to prevent VTE in patients with isolated temporary lower limb immobilization after trauma. We aimed to estimate and compare the clinical efficacy and the safety of the different thromboprophylactic treatments to determine the best strategy.

METHODS AND FINDINGS

We conducted a systematic review and a Bayesian network meta-analysis (NMA) including all available randomized trials comparing a pharmacological thromboprophylactic treatment to placebo or to no treatment in patients with leg immobilization after trauma. We searched Medline, Embase, and Web of Science until July 2021. Only RCT or observational studies with analysis of confounding factors including adult patients requiring temporary immobilization for an isolated lower limb injury treated conservatively or surgically and assessing pharmacological thromboprophylactic agents or placebo or no treatment were eligible for inclusion. The primary endpoint was the incidence of major VTE (proximal deep vein thrombosis, symptomatic VTE, and pulmonary embolism-related death). We extracted data according to Preferred Reporting Items for Systematic Reviews and Meta-analyses for NMA and appraised selected trials with the Cochrane review handbook. Fourteen studies were included (8,198 patients). Compared to the control group, rivaroxaban, fondaparinux, and low molecular weight heparins were associated with a significant risk reduction of major VTE with an odds ratio of 0.02 (95% credible interval (CrI) 0.00 to 0.19), 0.22 (95% CrI 0.06 to 0.65), and 0.32 (95% CrI 0.15 to 0.56), respectively. No increase of the major bleeding risk was observed with either treatment. Rivaroxaban has the highest likelihood of being ranked top in terms of efficacy and net clinical benefit. The main limitation is that the network had as many indirect comparisons as direct comparisons.

CONCLUSIONS

This NMA confirms the favorable benefit/risk ratio of thromboprophylaxis for patients with leg immobilization after trauma with the highest level of evidence for rivaroxaban.

TRIAL REGISTRATION

PROSPERO CRD42021257669.

Routine use of LMWH prophylaxis is associated with a lower incidence of venous thromboembolic events following an ankle fracture

BACKGROUND

Venous thromboembolic events (VTE) are well-known and serious complications following a trauma to the lower extremities. There is an ongoing debate on the benefit of low-molecular-weight heparin (LMWH) as prophylaxis following ankle fracture treatment. We examined the association between the incidence of VTE and the use of LMWH-prophylaxis following an ankle fracture, as well as factors affecting the risk of VTE.

METHODS

In this retrospective cohort study, data on ankle fractures and fracture treatment from the Swedish Fracture Register was linked to data from the Swedish National Patient Register and the Swedish Prescribed Drug Register. Patients with VTE and patients who received LMWH prophylaxis were identified. The treating orthopedic departments were sent a questionnaire about their guidelines regarding the use of LMWH prophylaxis.

RESULTS

222 cases of diagnosed VTE were identified among 14,954 ankle fractures. Orthopedic departments with higher-than-average use of LMWH prophylaxis among non-operatively treated ankle fractures had a lower incidence of VTE (OR 0.60, CI 0.39-0.92). Among operatively treated patients, departments with a guideline for the routine use of LMWH prophylaxis also had lower incidence of VTE (OR 0.56, CI 0.37-0.86). A later onset of VTE was seen among patients prescribed LMWH prophylaxis, with a mean of 56 days to onset (CI 44-67), compared to 39 days (CI 33-45) in patients without prescribed prophylaxis. During the first two weeks following injury, there was only one case of VTE in patients with prescribed LMWH, compared to 39 cases of VTE among patients without prescribed prophylaxis.

CONCLUSIONS

Routine use of LMWH in patients with operatively treated ankle fractures was associated with a lower incidence of VTE. A more frequent use of LMWH among patients with non-operatively treated ankle fractures were associated with a lower incidence of VTE. The onset occurred later among patients with LMWH-prophylaxis who still suffered a VTE.

Optimal management of older people with frailty non-weight bearing after lower limb fracture: a scoping review

BACKGROUND

Patients with lower limb fractures who are non-weight bearing are at risk of the complications of the associated immobility and disability, particularly people with frailty, but there is lack of clarity about what constitutes optimal care for such patients. A scoping literature review was conducted to explore what evidence is available for the management of this patient group.

METHODS

MEDLINE (PubMed) CINAHL, EMBASE and the Cochrane databases of published literature and the HMIC and SIGLE sites for grey literature were searched for primary research studies and expert reports, using an iterative approach initially including the key term 'non-weight bearing'. All study types were included. Analysis was by narrative synthesis.

RESULTS

No papers were identified from a search using the key phrase 'non-weight bearing'. With this term removed, 11 indirectly relevant articles on lower limb fractures were retrieved from the searches of the electronic databases comprising three observational studies, five non-systematic review articles, a systematic review, an opinion piece and a survey of expert opinion that had relevance to restricted weight bearing patients. The observational studies indicated depression, cognition and nutrition affect outcome and hence have indirect relevance to management. The non-systematic reviews articles emphasised the importance of maintaining strength and range of movement during immobilisation and advised an orthogeriatric model of care. Fourteen UK and 97 non-UK guidelines relevant to fragility fractures, falls and osteoporosis management were found in the grey literature, but none made specific recommendations regarding the management of any period of non-weight bearing.

DISCUSSION

These findings provide a summary of the evidence base that can be used in the development of a clinical guideline for these patients but is not sufficient. We propose that, a guideline should be developed for these patients using an expert consensus process.

Clinical risk assessment model to predict venous thromboembolism risk after immobilization for lower-limb trauma

BACKGROUND

Patients with lower-limb trauma requiring immobilization have an increased risk of venous thromboembolism (VTE). While thromboprophylaxis for all patients seems not effective, targeted thromboprophylaxis in high risk patients may be an appropriate alternative. Therefore, we aimed to develop and validate a risk assessment model for VTE risk: the TRiP(cast) score (Thrombosis Risk Prediction following cast immobilization).

METHODS

In this prediction model study, for development, data were used from the MEGA study (case-control study into the etiology of VTE) and for validation, data from the POT-CAST trial (randomized trial on the effectiveness of thromboprophylaxis following cast immobilization) were used. Model discrimination was calculated by estimating the Area Under the Curve (AUC). For model calibration, observed and predicted risks were assessed.

FINDINGS

The TRiP(cast) score includes 14 items; one item for trauma severity (or type), one for type of immobilization and 12 items related to patients' characteristics. Validation analyses showed an AUC of 0.74 (95%CI 0.61-0.87) in the complete dataset (n = 1250) and 0.72 (95%CI 0.60-0.84) in the imputed data set (n = 1435). The calibration plot shows the degree of agreement between the observed and predicted risks (intercept 0.0016 and slope 0.933). Using a cut-off score of 7 points in the POT-CAST trial (incidence 1.6%), the sensitivity, specificity, positive and negative predictive values were 76.1%, 51.2%, 2.5%, and 99.2%, respectively.

INTERPRETATION

The TRiP(cast) score provides a helpful tool in daily clinical practice to accurately stratify patients in high versus low-risk categories in order to guide thromboprophylaxis prescribing. To accommodate implementation in clinical practice a mobile phone application has been developed.

FUNDING

ZonMW VIMP grant:17110200011.

Pharmacological thromboprophylaxis to prevent venous thromboembolism in patients with temporary lower limb immobilization after injury: systematic review and network meta-analysis

BACKGROUND

Thromboprophylaxis has the potential to reduce venous thromboembolism (VTE) following lower limb immobilization resulting from injury.

OBJECTIVES

We aimed to estimate the effectiveness of thromboprophylaxis, compare different agents, and identify any factors associated with effectiveness.

METHODS

We undertook a systematic review and network meta-analysis (NMA) of randomized trials reporting VTE or bleeding outcomes that compared thromboprophylactic agents with each other or to no pharmacological prophylaxis, for this indication. An NMA was undertaken for each outcome or agent used, and a series of study-level network meta-regressions examined whether population characteristics, type of injury, treatment of injury, or duration of thromboprophylaxis were associated with treatment effect.

RESULTS

Data from 6857 participants across 13 randomized trials showed that, compared with no treatment, low molecular weight heparin (LMWH) reduced the risk of any VTE (odds ratio [OR]: 0.52; 95% credible interval [CrI]: 0.37-0.71), clinically detected deep vein thrombosis (DVT) (OR: 0.39; 95% CrI: 0.12-0.94) and pulmonary embolism (PE) (OR: 0.16; 95% CrI: 0.01-0.74), whereas fondaparinux reduced the risk of any VTE (OR: 0.13; 95% CrI: 0.05-0.30) and clinically detected DVT (OR: 0.10; 95% CrI: 0.01-0.86), with inconclusive results for PE (OR: 0.40; 95% CrI: 0.01-7.53).

CONCLUSIONS

Thromboprophylaxis with either fondaparinux or LMWH appears to reduce the odds of both asymptomatic and clinically detected VTE in people with temporary lower limb immobilization following an injury. Treatment effects vary by outcome and are not always conclusive. We were unable to identify any treatment effect modifiers other than thromboprophylactic agent used.

Different strategies for pharmacological thromboprophylaxis for lower-limb immobilisation after injury: systematic review and economic evaluation

BACKGROUND

Thromboprophylaxis can reduce the risk of venous thromboembolism (VTE) during lower-limb immobilisation, but it is unclear whether or not this translates into meaningful health benefit, justifies the risk of bleeding or is cost-effective. Risk assessment models (RAMs) could select higher-risk individuals for thromboprophylaxis.

OBJECTIVES

To determine the clinical effectiveness and cost-effectiveness of different strategies for providing thromboprophylaxis to people with lower-limb immobilisation caused by injury and to identify priorities for future research.

DATA SOURCES

Ten electronic databases and research registers (MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Database of Abstracts of Review of Effects, the Cochrane Central Register of Controlled Trials, Health Technology Assessment database, NHS Economic Evaluation Database, Science Citation Index Expanded, ClinicalTrials.gov and the International Clinical Trials Registry Platform) were searched from inception to May 2017, and this was supplemented by hand-searching reference lists and contacting experts in the field.

REVIEW METHODS

Systematic reviews were undertaken to determine the effectiveness of pharmacological thromboprophylaxis in lower-limb immobilisation and to identify any study of risk factors or RAMs for VTE in lower-limb immobilisation. Study quality was assessed using appropriate tools. A network meta-analysis was undertaken for each outcome in the effectiveness review and the results of risk-prediction studies were presented descriptively. A modified Delphi survey was undertaken to identify risk predictors supported by expert consensus. Decision-analytic modelling was used to estimate the incremental cost per quality-adjusted life-year (QALY) gained of different thromboprophylaxis strategies from the perspectives of the NHS and Personal Social Services.

RESULTS

Data from 6857 participants across 13 trials were included in the meta-analysis. Thromboprophylaxis with low-molecular-weight heparin reduced the risk of any VTE [odds ratio (OR) 0.52, 95% credible interval (CrI) 0.37 to 0.71], clinically detected deep-vein thrombosis (DVT) (OR 0.40, 95% CrI 0.12 to 0.99) and pulmonary embolism (PE) (OR 0.17, 95% CrI 0.01 to 0.88). Thromboprophylaxis with fondaparinux (Arixtra®, Aspen Pharma Trading Ltd, Dublin, Ireland) reduced the risk of any VTE (OR 0.13, 95% CrI 0.05 to 0.30) and clinically detected DVT (OR 0.10, 95% CrI 0.01 to 0.94), but the effect on PE was inconclusive (OR 0.47, 95% CrI 0.01 to 9.54). Estimates of the risk of major bleeding with thromboprophylaxis were inconclusive owing to the small numbers of events. Fifteen studies of risk factors were identified, but only age (ORs 1.05 to 3.48), and injury type were consistently associated with VTE. Six studies of RAMs were identified, but only two reported prognostic accuracy data for VTE, based on small numbers of patients. Expert consensus was achieved for 13 risk predictors in lower-limb immobilisation due to injury. Modelling showed that thromboprophylaxis for all is effective (0.015 QALY gain, 95% CrI 0.004 to 0.029 QALYs) with a cost-effectiveness of £13,524 per QALY, compared with thromboprophylaxis for none. If risk-based strategies are included, it is potentially more cost-effective to limit thromboprophylaxis to patients with a Leiden thrombosis risk in plaster (cast) [L-TRiP(cast)] score of ≥ 9 (£20,000 per QALY threshold) or ≥ 8 (£30,000 per QALY threshold). An optimal threshold on the L-TRiP(cast) receiver operating characteristic curve would have sensitivity of 84-89% and specificity of 46-55%.

LIMITATIONS

Estimates of RAM prognostic accuracy are based on weak evidence. People at risk of bleeding were excluded from trials and, by implication, from modelling.

CONCLUSIONS

Thromboprophylaxis for lower-limb immobilisation due to injury is clinically effective and cost-effective compared with no thromboprophylaxis. Risk-based thromboprophylaxis is potentially optimal but the prognostic accuracy of existing RAMs is uncertain.

FUTURE WORK

Research is required to determine whether or not an appropriate RAM can accurately select higher-risk patients for thromboprophylaxis.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017058688.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A review of emerging bone tissue engineering via PEG conjugated biodegradable amphiphilic copolymers

Defects in bones can be caused by a plethora of reasons, such as trauma or illness, and in many cases, it poses challenges to the current treatment approaches for bone repair. With increasing demand of bone bioengineering in tissue transplant, there is a need to source for sustainable solutions to induce bone regeneration. Polymeric biomaterials have been identified as a promising approach due to its excellent biocompatibility and controllable biodegradability. Specifically, poly(ethylene glycol) (PEG) is one of the most commonly investigated polymer for use in bio-related application due to its bioinertness and versatility. Furthermore, the hydrophilic nature enables it to be incorporated with hydrophobic but biodegradable polymers like, polylactide (PLA) and polycaprolactone (PCL), to create an amphiphilic polymer. This article reviews the recent synthetic strategies available for the construction of PEG conjugated polymeric system, analysis of PEG influence on the material properties, and provides an overview of its application in bone engineering.

Venous Thromboembolism in Podiatric Foot and Ankle Surgery

BACKGROUND

The extent to which podiatric surgeons follow venous thromboembolism guidelines is unknown. The aim of this study therefore, was 2-fold: (a) to determine the rate of venous thromboembolism following podiatric surgery and (b) to investigate the factors that influence the use of thromboprophylaxis.

METHODS

Data from 4238 patients who underwent foot and ankle surgery over 2 years were analyzed. Venous thromboembolism within the first 30 days following surgery was recorded using the Australasian College of Podiatric Surgeons surgical audit tool. Logistic regression analyses were undertaken to determine the factors that influenced thromboprophylaxis.

RESULTS

Of the 4238 patient records, 3677 records (87%) provided complete data (age range 2-94 years; mean ± SD, 49.1 ± 19.7 years; 2693 females). A total of 7 venous thromboembolic events (0.2% rate) were reported. Operative duration and age (OR 12.63, 95% CI 9.47 to 16.84, P < 0.01), postoperative immobilization (OR 6.94, 95% CI 3.95 to 12.20, P < 0.01), and a prior history of VTE (OR 3.41, 95% CI 1.01 to 11.04, P = 0.04) were the strongest predictors of thromboprophylaxis.

CONCLUSION

Podiatric foot and ankle surgery is associated with a low rate of venous thromboembolism. This may be due in part to the thromboprophylaxis regime implemented by podiatric surgeons, which closely aligns with current evidence-based guidelines.

LEVELS OF EVIDENCE

Level II: Prospective cohort study.