Tranexamic Acid (TXA) is now commonly used in major surgical operations including orthopaedics. The TRAC-24 randomised control trial aimed to assess if an additional 24 hours of TXA post – operatively in primary total hip (THA) and total knee arthroplasty (TKA) reduced blood loss. Contrary to other orthopaedic studies to date this trial included high risk patients. This paper presents the results of a cost analysis undertaken alongside this RTC.

TRAC-24 was a prospective randomised controlled trial on patients undergoing TKA and THA. Three groups were included, Group 1 received 1 g intravenous (IV) TXA perioperatively and an additional 24-hour post-operative oral regime, group 2 received only the perioperative dose and group 3 did not receive TXA. Cost analysis was performed out to day 90.

Group 1 was associated with the lowest mean total costs, followed by group 2 and then group 3. The difference between groups 1 and 3 −£797.77 (95% CI −1478.22, −117.32) were statistically significant. Extended oral dosing reduced costs for patients undergoing THA but not TKA. The reduced costs in groups 1 and 2 resulted from reduced length of stay, readmission rates, Accident and Emergency (A&E) attendances and blood transfusions.

This study demonstrated significant cost savings when using TXA in primary THA or TKA. Extended oral dosing reduced costs further in THA but not TKA.

Background

91% of blood loss in Total Hip Replacement (THR) occurs in the period after skin closure and the first 24 post-operative hours. TRAC-24 was established to identify if an additional 24-hour post-operative oral regime of Tranexamic acid (TXA) is superior to a once-only intravenous dose at surgery.

This study aimed to assess the effect of flexion and external rotation on measurement of femoral offset (FO), greater trochanter to femoral head centre (GT-FHC) distance, and neck shaft angle (NSA). Three-dimensional femoral shapes (n=100) were generated by statistical shape modelling from 47 CT-segmented right femora. Combined rotations in the range of 0–50° external and 0–50° flexion (in 10° increments) were applied to each femur after they were neutralised (defined as neck and proximal shaft axis parallel with detector plane). Each shape was projected to create 2D images representing radiographs of the proximal femora.

As already known, external rotation resulted in a significant error in measuring FO but flexion alone had no impact. Individually, neither flexion nor external rotation had any impact on GT-FHC but, for example, 30° of flexion combined with 50°of external rotation resulted in an 18.6mm change in height. NSA averaged 125° in neutral with external rotation resulting in a moderate increase and flexion on its own a moderate decrease. However, 50° degrees of both produced an almost 30 degree increase in NSA.

In conclusion, although the relationship between external rotation and FO is appreciated, the impact of flexion with external rotation is not. This combination results in apparent reduced FO, a high femoral head centre and an increased NSA. Femoral components with NSAs of 130° or 135° may historically have been based on X-ray misinterpretation. This work demonstrates that 2D to 3D reconstruction of the proximal femur in pre-op planning is a challenge.

Unknown femur orientation during X-ray imaging may cause inaccurate radiographic measurements. The aim of this study was to assess the effect of 3D femur orientation during radiographic imaging on the measurement of greater trochanter to femoral head centre (GT-FHC) distance.

Three-dimensional femoral shapes (n=100) of unknown gender were generated using a statistical shape model based on a training data of 47 CT segmented femora. Rotations in the range of 0° internal to 50° external and 50° of flexion to 0° of extension (at 10 degree increments) were applied to each femur. A ray tracing algorithm was then used to create 2D images representing radiographs of the femora in known 3D orientations. The GT-FHC distance was then measured automatically by identifying the femoral head, shaft axis and tip of greater trochanter.

Uniaxial rotations had little impact on the measurement with mean absolute error of 0.6 mm and 3.1 mm for 50° for pure external rotation and 50° pure flexion, respectively. Combined flexion and external rotation yielded more significant errors with 10° around each axis introducing a mean error of 3.6 mm and 20° showing an average error of 8.8 mm (Figure 1.). In the cohort we studied, when the femur was in neutral orientation, the tip of greater trochanter was never below the femoral head centre.

Greater trochanter to femoral head centre measurement was insensitive to rotations around a single axis (i.e. flexion or external rotation). Modest combined rotations caused the tip of greater trochanter to appear more distal in 2D and led to deviation from the true value. This study suggests that a radiograph with the greater trochanter appearing below femoral head centre may have been acquired with 3D rotation of the femur.

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Introduction

The results of cementless total hip arthroplasty (THA) vary with data from the UK national Joint Registry being less favourable than that from the Australian registry. The senior author started using a fully cementless THA in 2005 and we aimed to gauge the performance of the implants based on their revision data.