Introduction. Pulmonary embolism (PE) complicates up to 1% of total joint arthroplasties (TJA). Many PE treatment guidelines call for immediate initiation of therapeutic anticoagulation. Options include Xa inhibitors, Enoxaparin, and Warfarin. Deciding between these is a balance of the efficacy and the risks. Little data exists regarding the risks of each of these treatment options for treating PE in arthroplasty patients. Methods. We examined the records of 29,270 patients who underwent a primary total joint arthroplasty (TJA), defined as a unilateral total knee arthroplasty (TKA) (18,987) or total hip arthroplasty (THA) (10,283), between 2/2016 and 12/2018 at our institution and identified 338 (242 TKA, 96 THA) patients who developed an in-hospital PE treated with therapeutic anticoagulation. The patients were treated with therapeutic doses of Xa inhibitors, enoxaparin or warfarin. The type and frequency of complications were determined and classified as major or minor. Major complication included: bleeding requiring surgery, GI bleed requiring treatment, >2 unit transfusion and mortality. Minor complications included wound drainage, bleeding not requiring surgery, and thrombocytopenia. Results. Overall complication rates were high for all treatments. Xa inhibitors had the lowest complication rate at 14% compared to 20% for enoxaparin and 20.7% for warfarin though the difference did not quite reach statistical significance (p=.054). Both major and minor complication were lower with Xa inhibitors, but again the difference was not statistically significant (p=0.67). There was no significant difference in complications between TKA groups (p=0.73) or THA groups (p=0.83). Gender and body mass index were not predictive of major or minor complications. Discussion. Our results demonstrate high complication rates associated with modern therapeutic anticoagulation protocols for perioperative PE following TJA. Patients who receive therapeutic anticoagulation postoperatively are at high risk for complication. Xa inhibitors may decrease these risks, but larger studies are required

Hip fractures are a common cause of morbidity and mortality in the elderly, with approximately 30,000 hip fractures a year in Canada. Many hip fracture patients are prone to heart failure and present anticoagulated with Warfarin for medical comorbidities including atrial fibrillation or previous thromboembolic disease. Reversal of warfarin anticoagulation to an INR < 1.5 preferred for surgery but this often contributes to a delay to hip fracture surgery, which increases patient pain, morbidity, mortality, and length of stay Octaplex is a small-volume prothrombin complex concentrate (PCC) that reverses Warfarin-related anticoagulation in 15–60 minutes. It has been shown to be safe and effective in the management of intracranial and gastrointestinal bleeding in warfarinised patients. It is recommended by Bone and Joint Canada as an option for urgent warfarin reversal in hip fracture patients. However, there has been no published literature on the use of Octaplex or other PCCs in orthopaedic patients. Our objective is to assess the effectiveness of Octaplex for rapid reversal of warfarin anticoagulation in hip fracture patients. A database review of all patients who received Octaplex was performed. Medical records of all hip fracture patients in Calgary who received Octaplex between December 2009 and February 2015 were reviewed. After application of inclusion and exclusion criteria, 33 patients were identified. A timeline of International Normalised Ratio (INR), Octaplex administration, and hip fracture surgery was recorded. Mortality and complications were assessed at 30 days. A single dose of Octaplex corrected the INR to < 1.5 in 29 cases (88%). Median time from administration of Octaplex to a measured INR < 1.5 was 1.1 hours. Median time from admission to hip fracture surgery was 22 hours. Mortality at 30 days was 15.2%, mostly from cardiac arrest. A further 12% of patients developed cardiac or thrombotic complications. Multiple medical comorbidities were common including coronary artery disease (55%), congestive heart failure (45%), and chronic pulmonary disease (39%). Patients who received both fresh frozen plasma (FFP) and Octaplex for warfarin reversal had much higher mortality than those who only received Octaplex (40% vs 4.3% mortality at 30 days), but also had more medical comorbidities. Octaplex is effective at rapidly reversing warfarin anticoagulation and reducing time to surgery, potentially reducing the morbidity and mortality of hip fractures. Administration of both Octaplex and FFP were associated with higher early mortality in this case series. Further research is required to assess the safety of Octaplex, vitamin K, and FFP for reversal of warfarin anticoagulation in this population

We made a prospective study of the incidence of fatal pulmonary embolism in patients after total knee replacement with no prophylactic anticoagulation. There were 499 consecutive patients having 527 knee replacements. They all wore anti-thromboembolic stockings and were mobilised 48 hours after surgery. No patient was lost to follow-up. One patient died of pulmonary embolism 22 days after operation. There were no other deaths within three months of operation. The incidence of fatal pulmonary embolism was 0.19% (95% confidence interval: 0 to 0.6%). Fatal pulmonary embolism is rare after total knee replacement without prophylactic anticoagulation and the routine anticoagulation of these patients is of doubtful value

Introduction: The use of coumadin for prophylaxis against thromboembolism (TE) following total joint arthroplasty is the standard of care. In light of recent publication of the American College of Chest Physicians (ACCP), we altered our anticoagulation protocol to be compliant with the recommendations. This study evaluates the incidence of TE and bleeding complications following TJA when low dose coumadin vs. regular dose coumadin was administered. Methods: 987 consecutive patients undergoing total joint arthroplasty by a single surgeon between the years of 2004–2005 were included. 446 patients operated on during the 2004 received low dose coumadin (intended INR 1.5–1.7) whilst 541 patients undergoing TJA during 2005 were given regular dose coumadin (intended INR 2–2.5). Results: The mean INR for patients operated during the year 2005 was significantly higher than the INR for patients receiving TJA in 2004. There were more complications in 2005. There were 13 PE, 44 wound drainage, 4 DVT, and 11 hematoma formation (requiring surgical evacuation) during the year 2005 compared to 10 PE, 26 wound drainage, 6 DVT, and 5 hematoma formation in 2004. The difference for all complications except DVT was significant. Conclusion: This study confirms the commonly held belief that aggressive anticoagulation does carry a higher incidence of complications such as wound drainage and bleeding. It appears that administering higher dose coumadin increased the bleeding complications without conferring additional protection against thromboembolic disease

We used the D-dimer level as a measure for the early diagnosis of deep vein thrombosis (DVT), which can cause fatal pulmonary thromboembolism (PTE), following total hip arthroplasty (THA). Recently, we have performed anticoagulation therapy, in addition to the use of elastic stocking and intermittent pneumatic compression, for the prevention of DVT. In the present study, we examined the effect of administration of anticoagulation drugs on the changes in the D-dimer level. Of 123 patients who had undergone THA between April 2003 and October 2007, 70 patients who were available for 3 or more measurements of the D-dimer level were included in this study. These 70 patients were divided into the following three groups: N group consisting of 30 patients who were not given anticoagulation drugs (4 males, 26 females; mean age 69 years (45–87 years); mean body mass index (BMI) 24.1 (15.8–28.5)), W group consisting of 23 patients who were administered dose-adjusted warfarin at a dose of 5 mg within 3 days after surgery and at 1–3 mg following 1-day rest (3 males, 20 females; mean age 62 years (48–83 years); mean BMI 24.1 (17.8–35.9)), and F group composed of 15 patients who were given fondaparinux (2.5 mg) between postoperative days 1 and 14 (6 males, 11 females; mean age 64 years (51–81 years); mean BMI 23.1 (18.2–31.6)). There was no significant difference in sex ratio and BMI between the three groups, while a significant difference in age was found between the N and F groups. The D-dimer level was measured on days 3, 7, 10, 14 and 21 and changes in the median D-dimer level were compared between groups. In the N group, the D-dimer level was around 8 μg/ml between postoperative days 3 and 10 and exceeded 10 μg/ml on postoperative day 14. In the W group, the D-dimer level was around 8 μg/ml between postoperative days 3 and 14 and decreased thereafter. In the F group, the D-dimer level was less than 3 μg/ ml on postoperative day 3, increased gradually thereafter until postoperative day 14, reaching the maximum level of approximately 8 μg/ml, and then decreased thereafter. The D-dimer level was significantly different between the N and F groups and between the W and F groups on day 3, between the N and F groups and between the W and F groups on day 7, and between the N and W groups on day 21. With regard to hemorrhagic adverse events, neither major nor minor bleeding event was observed in either the W or F group. The present study suggested that fondaparinux is effective for preventing DVT in an early postoperative period, with relatively low D-dimer levels observed between postoperative days 3 and 10. We expect that various types of anticoagulation drugs will be used in the future. Elucidating the effect of these drugs on the D-dimer level will help in the early diagnosis of DVT

Introduction. There is insufficient data on the trends of anticoagulation after total knee arthroplasty (TKA) in the USA, and the efficacy and safety of rivaroxaban, beyond randomized clinical trials and small cohort studies. Patients and Methods. Using the Truven Health MarketScan database, we retrospectively evaluated new anticoagulation prescriptions after elective TKA from 2010 to 2015. The frequency of deep vein thrombosis (DVT), pulmonary embolism (PE), and adverse events, within 90 days, were then evaluated in 24,856 new users of warfarin and 21,398 new users of rivaroxaban in commercially insured patients (COM), and 15,483 new users of warfarin and 8,997 new users of rivaroxaban in Medicare supplement patients (MED). Data was analyzed by odds ratios using logistic regression models with stabilized inverse probability treatment weighting. Results. Warfarin use decreased from approximately 50% to 17% in COM patients and 60% to 25% in MED patients. Rivaroxaban use increased from 0 to 35% in COM patients and from 0 to 39% in MED patients. Older patients, females, a history of DVT, renal impairment, use of antiplatelet agents or surgery performed as an outpatient had lower odds of getting rivaroxaban. Patients in Western region and having surgery in 2015 had higher odds of getting rivaroxaban. COM patients with capitated insurance plans and a history of PE had lower odds of rivaroxaban initiation. MED patients with atrial fibrillation, cardiovascular disease or hyperlipidemia had lower odds of rivaroxaban initiation. Warfarin users had significantly higher odds ratio of DVT (OR 2.06 in COM patients and OR 2.21 in MED patients) and PE (OR 2.03 in COM patients and OR 2.16 in MED patients) than rivaroxaban users. There were no statistically significant differences in the bleeding risk between the two agents, but warfarin users had a significantly higher odds ratio of periprosthetic infection in both COM (1.57) and MED (1.79) patients. Conclusions. There has been an increase in prophylaxis with rivaroxaban, and a decrease in both warfarin and LMWH use after elective TKA over four years. Rivaroxaban had lower odds ratio of both DVT and PE than warfarin, and bleeding risks were similar. For figures, tables, or references, please contact authors directly

Aims. The purpose of this article was to review the current literature pertaining to the use of mobile compression devices (MCDs) for venous thromboembolism (VTE) following total joint arthroplasty (TJA), and to discuss the results of data from our institution. Patients and Methods. Previous studies have illustrated higher rates of post-operative wound complications, re-operation and re-admission with the use of more aggressive anticoagulation regimens, such as warfarin and factor Xa inhibitors. This highlights the importance of the safety, as well as efficacy, of the chemoprophylactic regimen. Results. Studies have shown a symptomatic VTE rate of 0.92% with use of MCDs for prophylaxis, which is comparable with rates seen with more aggressive anticoagulation protocols. A prior prospective study found that use of a pre-operative risk stratification protocol based on personal history of deep vein thrombosis, family history of VTE, active cancer, or a hypercoaguable state allowed for the avoidance of aggressive prophylactic anticoagulation in over 70% of patients while maintaining a low incidence of symptomatic VTE. Conclusion. Further investigation is needed into the role of aspirin in VTE prophylaxis as well as the efficacy of MCDs as stand-alone prophylactic treatment. Cite this article: Bone Joint J 2017;99-B(1 Supple A):8–13

Bleeding related wound complications including deep infection, superficial infection and haematoma cause significant morbidity in lower limb joint arthroplasty surgery. It has been observed anecdotally that patients requiring therapeutic anti-coagulation within the peri-operative period have higher rates of bleeding related complications and those requiring intravenous heparin particularly appear to do poorly. The aim of this study is to investigate the relationship between post-operative bleeding and wound complications in the patient requiring therapeutic warfarin, plus or minus heparin, in total hip arthroplasty surgery. This is a retrospective cohort study reviewing 1047 primary total hip replacements performed in a single centre over a five year period and comparing outcomes of the patients on warfarin (89) with a double-matched control group of patients not on warfarin (179). Outcomes included rates of deep infection, excessive wound ooze or haematoma, superficial infection, return to OT for washout and need for revision operation. The study group was then sub analysed comparing those on IV heparin plus oral warfarin, to those on warfarin alone. The warfarin group had significantly higher risk of deep joint infection (9% vs 2.2% p= 0.023), haematoma/wound ooze (28% vs 4% p < 0.001) and superficial infection (13.5% vs 2.2% p < 0.001) compared to the control group. In the sub analysis of the study group, those on IV heparin had significantly higher risk of haematoma/wound ooze (44% vs 28% p= 0.023) than those on warfarin alone. The requirement of therapeutic anti-coagulation in the peri-operative period is a tenuous balance between the complications of thrombo-embolic disease and bleeding-related morbidity. In the past, perhaps the full burden of bleeding related complications has not been appreciated, but now improved understanding will enable the both the surgeon and the patient to make more informed decisions regarding therapeutic anticoagulation in elective arthroplasty surgery

Introduction. Many pharmacologic agents have been used for venous thromboembolism (VTE) prophylaxis after elective total hip arthroplasty (THA). Rivaroxaban was the first novel oral anticoagulant approved for THA patients, but its actual efficacy and safety in clinical practice, beyond randomized trials, is unknown. Materials and Methods. This is a retrospective study, using the Truven Health MarketScan database, of anticoagulation medication prescriptions after elective THA, in both commercially insured (CI) and Medicare supplement insured (MS) patients, from 2010 to 2015. After exclusions, there were 83,179 CI and 50,534 MS patients available for analysis. There were 12,876 new users of warfarin (W) and 10,892 new users of rivaroxaban (R) in CI patients, and 7,416 new users of W and 4,739 new users of R in MS patients. We asked the following questions: (1) What were the trends and predictive factors for anticoagulant use after elective THA? (2) What was the actual clinical efficacy: frequency of deep vein thrombosis (DVT) and pulmonary embolism (PE), and frequency of adverse events within 90 days with the two most commonly used oral agents, rivaroxaban and warfarin, from June 2011 to September 2015? Data was analyzed for each anticoagulant by odds ratios using logistic regression models with stabilized inverse probability treatment weighting. Results. There was a change in use of anticoagulants after R approval. Use of W decreased from approximately 50% each in 2010 in both insurance cohorts to 10% in CI patients and 30% in MS patients in 4th quarter 2015. The use of R increased from 0 to 33% in both cohorts from 2011 to 2015. In the multivariate analysis, in CI patients, females had lower odds of getting R, and patients in Western region had higher odds of getting R; in MS patients, increasing age had reduced odds of getting rivaroxiban, but Western region and surgery in 2015 had higher odds. Patients with capitated insurance plans and renal impairment had lower odds of R initiation, but a history of cardiovascular disease or hypertension had higher odds. In 90 days after THA, patients given R had significantly lower odds ratio of both DVT and PE in both CI patients (DVT: 1.54 with W, 0.54 with R; PE: 2.12 with W, 0.73 with R) and MS patients (DVT: 3.01 W, 1.73 R; PE: 4.09 W, 1.88 R). With logistic regression analysis, users of W had significantly higher odds ratio of both DVT (CI 2.63 and MS 1.78) and PE (CI 2.60 and MS 2.09) than R. There was no significant difference in rates of bleeding between W and R, but W had higher odds ratio than R of prosthetic joint infection (PJI) in both CI (1.574) and MS (1.790) cohorts. Conclusions. There has been an increase in VTE prophylaxis with R, and a decrease in both W and LMWH use after elective THA over four years. Patient factors, insurance type, and comorbidities were associated with this change. In actual clinical efficacy, R had lower odds ratio of both DVT and PE than W, and bleeding risks were similar. The association of W with an increased odds ratio of PJI compared to R requires further study

Aims

The optimal management of an infrapopliteal deep venous thrombosis (IDVT) following total knee arthroplasty (TKA) remains unknown. The risk of DVT propagation and symptom progression must be balanced against potential haemorrhagic complications associated with administration of anticoagulation therapy. The current study reports on a cohort of patients diagnosed with IDVT following TKA who were treated with aspirin, followed closely for development of symptoms, and scanned with ultrasound to determine resolution of IDVT.

Introduction

This is a retrospective review of the incidence of deep venous thrombosis (DVT) in 679 consecutive unilateral primary hip arthroplasty procedures performed between January 2007 and December 2010 managed with no anticoagulants. Mean age at operation was 58 years. Mean BMI was 26. The prophylaxis regimen included hypotensive epidural anesthesia, compression stockings, intermittent calf compression, early mobilization and an antiplatelet agent.

Fractures of the Proximal Femur are a common and disabling injury requiring hospital admission and surgical treatment leading to approximately 86,000 inpatient episodes annually in the UK, with such patients occupying more than 20% of NHS orthopaedic beds. Based on current trends the number of hip fractures may rise to 120,000 per annum by 2015.

As the age of the population increases, so does the prevalence of concomitant medical conditions. Atrial Fibrillation is rising in the general population. Recently, the benefit of treating these patients with warfarin to prevent stroke has been shown; as a consequence, the number of patients being treated with warfarin is on the increase.

We have performed a retrospective study of all patients admitted to our unit with Fractures of the neck of the femur between 2001 and 2006, from the Accident and Emergency department with a primary diagnosis of Proximal Femoral Fracture (1987 patients). 138 patients were on long term warfarin at the time of their admission (6.9% of admissions). 90.4% were being warfarinised for AF, 7.6% for DVT and the rest for other indications. Of these Patients only 12 (8.7%) received active reversal to their warfarin. (All received vitamin K either orally or Intravenously). The average delay to theatre attributable to warfarin therapy was 41.1 hours (p-0.001). Active reversal allowed this delay to be negated (p-0.01), and did not delay the reloading of warfarin post-operatively (p-0.012). It also allowed an average of 10.2 days earlier discharge from the orthopaedic unit (p-0.001).

This study shows that significant delays occur because of Warfarinisation of these patients and that active reversal seems to be beneficial in expediting surgical treatment and discharge from the orthopaedic unit.

INTRODUCTION

Warfarin remains the treatment of choice for the majority of patients with venous thromboembolism, atrial fibrillation and valvular heart disease or valve replacement unless contraindicated. Poor management of patients on warfarin often leads to delay in surgery, life threatening bleeding during or after operation and unnecessary delay in discharge from hospitals in United Kingdom.

We describe three patients with a compartment syndrome of the thigh, two after total hip replacement and one after total knee replacement. Two of the patients were fully anticoagulated.

A compartment syndrome of the thigh is a rare, but important complication of joint replacement surgery if patients are receiving anticoagulants. Close observation is needed and when indicated monitoring of the intracompartmental pressure should be done. Early recognition of the signs and symptoms of an acute compartment syndrome and knowledge of the anatomy of the compartments of the thigh will help in the diagnosis and treatment of this potentially devastating complication.

Aims. We studied the safety and efficacy of multimodal thromboprophylaxis in patients with a history of venous thromboembolism (VTE) who undergo total hip arthroplasty (THA) within the first 120 postoperative days, and the mortality during the first year. Multimodal prophylaxis includes discontinuation of procoagulant medications, VTE risk stratification, regional anaesthesia, an intravenous bolus of unfractionated heparin prior to femoral preparation, rapid mobilization, the use of pneumatic compression devices, and chemoprophylaxis tailored to the patient’s risk of VTE. Methods. Between 2004 to 2018, 257 patients with a proven history of VTE underwent 277 primary elective THA procedures by two surgeons at a single institution. The patients had a history of deep vein thrombosis (DVT) (186, 67%), pulmonary embolism (PE) (43, 15.5%), or both (48, 17.5%). Chemoprophylaxis included aspirin (38 patients), anticoagulation (215 patients), or a combination of aspirin and anticoagulation (24 patients). A total of 50 patients (18%) had a vena cava filter in situ at the time of surgery. Patients were followed for 120 days to record complications, and for one year to record mortality. Results. Postoperative VTE was diagnosed in seven patients (2.5%): DVT in five, and PE with and without DVT in one patient each. After hospitalization, three patients required readmiss-ion for evacuation of a haematoma, one for wound drainage, and one for monitoring of an elevated international normalized ratio (INR). Seven patients died (2.5%). One patient died five months postoperatively of a PE during open thrombectomy. She had discontinued anticoagulation. One patient died of a haemorrhagic stroke while receiving Coumadin. PE or bleeding was not suspected in the remaining five fatalities. Conclusion. Multimodal prophylaxis is safe and effective in patients with a history of VTE. Postoperative anticoagulation should be prudent as very few patients developed VTE (2.5%) or died of suspected or confirmed PE. Mortality during the first year was mostly unrelated to either VTE or bleeding. Cite this article: Bone Joint J 2020;102-B(7 Supple B):71–77

Use of anticoagulants for thromboembolic prophylaxis is strongly supported by evidence. However, the use of these medications beyond the prophylactic period is poorly understood. We identified anticoagulant naïve patients that underwent hip or knee replacement between 2012 and 2019 from an arthroplasty registry and probabilistically linked 3,018 surgeries with nationwide pharmaceutical claims data. Rates of anticoagulation use were examined during the early (<= 60 days post-discharge), mid-term (61–180 days post-discharge) and long-term (181–360 days post-discharge) periods. Multivariable logistic regression analysis was performed to identify patient- and surgery-related factors associated with long-term anticoagulant use. Anticoagulants were supplied to 20% of arthroplasties within 60 days of discharge, 7% between 61–180 days, and 10% between 181–360 days. Older age, obesity, increased comorbidity burden, a longer length of stay, occurrence of a complication necessitating anticoagulation and dispensation of an anticoagulant within 60 days of discharge were all risk factors for long-term anticoagulant use. Given the risks associated with unnecessary use of these medications, certain patients who are prescribed anticoagulants beyond prophylactic period may benefit from specialist medication review in the months following surgery

Aims. Prosthetic joint infection (PJI) remains a serious complication that is associated with high morbidity and costs. The aim of this study was to prepare a systematic review to examine patient-related and perioperative risk factors that can be modified in an attempt to reduce the rate of PJI. Materials and Methods. A search of PubMed and MEDLINE was conducted for articles published between January 1990 and February 2018 with a combination of search terms to identify studies that dealt with modifiable risk factors for reducing the rate of PJI. An evidence-based review was performed on 12 specific risk factors: glycaemic control, obesity, malnutrition, smoking, vitamin D levels, preoperative Staphylococcus aureus screening, the management of anti-rheumatic medication, perioperative antibiotic prophylaxis, presurgical skin preparation, the operating room environment, irrigant options, and anticoagulation. Results. Poor glycaemic control, obesity, malnutrition, and smoking are all associated with increased rates of PJI. Vitamin D replacement has been shown in preliminary animal studies to decrease rates of PJI. Preoperative Staphylococcus aureus screening and appropriate treatment results in decreased rates of PJI. Perioperative variables, such as timely and appropriate dosage of prophylactic antibiotics, skin preparation with chlorohexidine-based solution, and irrigation with dilute betadine at the conclusion of the operation, have all been associated with reduced rates of PJI. Similarly, aggressive anticoagulation and increased operating room traffic should be avoided to help minimize risk of PJI. Conclusion. PJI remains a serious complication of arthroplasty. Surgeons should be vigilant of the modifiable risk factors that can be addressed in an attempt to reduce the risk of PJI

Abstract. Introduction. The Wells score is commonly used to assess the risk of proximal Deep Vein Thrombosis (DVT) following Knee Arthroplasty (KA). The National Institute for Health and Care Excellence (NICE) guidelines recommend an Ultrasound scan in patients with a Wells score of 2 points or more. We wanted to assess how often this protocol resulted in a scan being done and how many were negative. Methodology. Details of all postoperative Ultrasound scans performed up to 90 days were audited in a high-volume unit between 1st January 2016 and 31st December 2020. This included all Lower Limb Arthroplasty patients. Results. Out of a total of 4955 KA (4506 Total Knee Arthroplasty, 449 Unilateral Knee Arthroplasty), 449 (9.1%) had a total of 561 scans, with 17 (3.0%) scans demonstrating a proximal DVT. Thus 97.0% of Ultrasound scans were negative. Conclusion. The present NICE guidelines with the two-Level DVT Wells score are inappropriate for the management of suspected proximal DVT following KA. We propose that swelling that fails to reduce after 4 hours of elevation, or new swelling after a period of recumbent rest, would be more appropriate indications for a scan and negative scans should not be repeated without a change in symptoms. Unless there are pressing clinical indications, therapeutic anticoagulation should not commence in the absence of a diagnosis

Thrombelastography (TEG) is a point-of-care tool that can measure clot formation and breakdown using a whole blood sample. We have previously used serial TEG analysis to define hypercoagulability and increased venous thromboembolism (VTE) risk following a major fracture requiring surgical treatment. Additionally, we have used serial TEG analysis to quantify the prolonged hypercoagulable state and increased VTE risk that ensues following a hip fracture. Recently developed cartridge-based platelet mapping (PLM) using TEG analysis can be used to activate platelets at either the adenosine diphosphate (ADP) receptor or at the Thromboxane A2 (AA) receptor, in order to evaluate clot strength when platelets are activated only through those specific receptors. This study aim was to evaluate platelet contribution to hypercoagulability, in order to identify potential therapeutic targets for VTE prevention. We hypothesized that there would be a platelet-predominant contribution to hypercoagulability following a hip fracture. Patients aged 50 years or older with a hip fracture treated surgically were enrolled in this prospective cohort study. Exclusion criteria were: prior history of VTE, active malignancy, or pre-injury therapeutic dose anticoagulation. Serial TEG and PLM analyses were performed at admission, post-operative day (POD) 1, 3, 5, 7 and at 2-, 4-, 6- and 12-weeks post-operatively. All patients received thromboprophylaxis with low molecular weight heparin (LMWH) for 28 days post-operatively. Hypercoagulability was defined as maximal amplitude (MA; a measure of clot strength) over 65mm based on TEG analysis. Independent samples t-tests were used to compare MA values with this previously established threshold and a mixed effects linear regression model was used to compare MA values over time. Independent samples t-tests and Chi-sqaured analyses were used to compare between the surgical fixation and arthroplasty groups. Forty-six patients with an acute hip fracture were included, with a mean age of 77.1 (SD = 10.6) years, with 61% (N=11) being female. Twenty-six were treated with arthroplasty (56.5%), while the remainder underwent surgical fixation of their hip fractures. TEG analysis demonstrated post-operative hypercoagulability (mean MA over 65mm) at all follow-up timepoints until 12-weeks. PLM identified a platelet-mediated hypercoagulable state based on elevated ADP-MA and AA-MA, with more pronounced platelet contribution demonstrated by the AA pathway. Patients treated with arthroplasty had significantly increased AA-MA compared with ADP-MA at POD 3 and at the 12-week follow-up. Thrombelastography can be used to identify hypercoagulability and increased risk for VTE following a hip fracture. Platelet mapping analysis from this pilot study suggests a platelet-mediated hypercoagulable state that may benefit from thromboprophylaxis using an anti-platelet agent that specifically targets the AA platelet activation pathway, such as acetylsalicylic acid (ASA). This research also supports differences in hypercoagulability between patients treated with arthroplasty compared to those who undergo fracture fixation