Introduction: Venous thromboembolism is a major cause of morbidity and mortality in hospitalised patients and patients undergoing major orthopaedic surgery are at high risk from venous thromboembolism. Thromboprophylaxis, both mechanical and chemical, is commonly administrated to reduce fatality from thromboembolism after surgery. However, there is no convincing evidence in the literature demonstrating that routine chemothromboprophylaxis reduces death rates from pulmonary embolus. Furthermore, it is unclear from the literature which thromboprophylactic agent, if any, should be used.

Recent NICE guidelines have recommended that heparin should be routinely administered to patients under-going THR to prevent thromboembolism, although it is unclear from the existing evidence if heparin is the most effective. However, research has suggested that aspirin, which is a low cost prophylactic agent, is effective in preventing DVT and PE after orthopaedic surgery. The aim of this study was to determine the 90-day mortality rate after THR using aspirin as a prophylactic agent.

Patients and Methods: Between 2003–2006, 2,286 patients underwent primary THR and 372 patients underwent revision hip replacement (RHR). Routine chemothromboprophylaxis consisting of aspirin 75mg daily for 6 weeks. In addition all patients were treated with anti-thromboembolic stockings. 40mg of subcutaneous clexane, in lieu of aspirin, was given daily to all patients who had previously suffered from a pulmonary embolus or deep venous thrombosis. Patients who died within 90 days of surgery had their death certificates examined. Retrieval at 90 days with regard to death was 100%.

Results:

Primary THR

One patient (0.04%) died within 30 days of surgery and a further 3 (0.13%) died between day 30 and day 90, giving a total mortality at 90 days of 0.17% (4/2,286). One patient (0.04%) died from PE and the other 3 patients (0.13%) died from non-vascular causes.

Discussion: This study found that the 30-day mortality rate for primary THR and RHR was 0.08% and the 90-day mortality rate was 0.23%. In this study, there was only one death from PE and no deaths from arterial complications. Therefore, although NICE guidelines suggest the use of heparin, this study found that routine aspirin administration is beneficial in protecting against early death after THR because of both thromboembolism and adverse arterial events.

Thromboprophylaxis after elective orthopaedic surgery remains controversial. Recent guidelines from the National Institute for Clinical Excellence (NICE) have suggested that low molecular weight heparin should be given to all patients undergoing total hip replacement. The British Orthopaedic Association is currently debating this guideline with NICE, as it is not clear whether published evidence supports this view. We present the early mortality in our unit after total hip replacement using aspirin as chemical thromboprophylaxis. The 30-day and 90-day mortality after primary total hip arthroplasty was zero. We compare this with that reported previously from our unit without using chemical thromboprophylaxis. With the introduction of routine aspirin thromboprophylaxis, deaths from cardiovascular causes have dropped from 0.75% to zero.

These results demonstrate that there is a strong argument for the routine administration of aspirin after elective total hip replacement.

A research programme has been directed at the mechanism by which car occupants sustain ankle and hind-foot injuries. The severe injuries that are most associated with long term disability and high socio-economic cost have been investigated. Although seat belts and air bags have had a beneficial effect on injuries to most body regions including pelvic, femur and knee injuries, no protective effect has been demonstrated for below knee injuries. Only by understanding the mechanism of injuries to the leg below the knee will it be possible to design improved protection in the future.

Twenty three post mortem human surrogate (PMHS) limbs were impacted using a test set up that was developed to simulate the loading conditions seen in a frontal collision in 3 different positions – A, B & C. The impactor head (5cm x 10cm wide), was instrumented with an accelerometer and linear potentiometer. The impacting force was generated using a bungee-powered sled mounted on steel bearings. Three PMHS legs were tested In Position A (impactor head centred in line with the tibial axis), 9 PMHS legs were tested in Position B (impactor head centred on the anterior tibial margin) and 11 PMHS legs were tested in Position C (impactor head centred 2.5cm anterior to the anterior tibial margin). Active dorsiflexion was simulated through the Achilles tendon and prior to the application of Achilles tension a tibial pre-load (500 to1500N) was applied via a ‘jacking-plate’ applied to the proximal end of the tibia.

During impact testing, bone failure (fractures) occurred at impact loads of 5.7+/−1.9 kN (resultant tibial failure load 6.4+/−1.9 kN) and the following injuries were generated: 9 intra-articular calcaneal fractures; 1 talar neck and 2 talar body fractures; 3 intra-articular distal tibial (pilon) fractures; 2 malleolar fractures; 3 soft tissue injuries and in 3 cases there was no detectable injury. The impact test conditions were replicated with a Hybrid III leg in a first attempt at developing injury risk functions for the dummy.

This study has demonstrated the importance of preload through muscle tension in addition to the intrinsic properties of PMHS specimens in the generation of severe ankle and hindfoot injury.