Elsevier

The Knee

Volume 10, Issue 1, March 2003, Pages 81-85
The Knee

Can knee position save blood following total knee replacement?

https://doi.org/10.1016/S0968-0160(02)00076-5Get rights and content

Abstract

Previous research showed knee flexion at 70° for 6 h following total knee replacements (TKR) reduced wound drainage by 30%. However, wound drainage may not represent total blood loss and obstruction of the drain in flexion or the relative elevation of the knee could have caused the reduction in drainage. We wished to confirm that this simple, cheap method not only reduced wound drainage but also total haemoglobin loss and determine what part elevation or drain obstruction may play. Sixty consecutive TKR patients were randomly allocated to three groups. Group 1—knee extended and level with bed. Group 2—leg elevated 35° at the hip with knee flexed to 70° for 6 h post-operatively. Group 3—leg elevated 35° at the hip with knee extended for 6 h post-operatively. We assessed wound drainage over 48 h, calculated haemoglobin loss, total blood transfusion, pain, arc of motion, swelling, length of hospital stay and complications. We found knee flexion and knee elevation in extension reduced haemoglobin loss by 25%. Compromise to tissue oxygenation has been reported with knee flexion. We recommend elevation of the leg at 35° from the hip with the knee extended. This offers a simple, safe and effective way to reduce total blood loss by 25%.

Introduction

Blood loss following total knee replacement (TKR) can be substantial. Allogenic blood transfusion has associated risks; these include infection, allergic reaction and immunosuppression [1], [2]. In order to minimise transfusion-related risks, post-operative blood loss should be minimised.

Previous research showed knee flexion at 70° for 6 h following TKR reduced wound drainage by 33% [3]. In the previous study, 48-h wound drainage was the only outcome measure and blood transfusion rate was not assessed. Popliteal vein compression when the knee was extended was proposed as an explanation for the decreased drainage with flexion. However, drain obstruction or relative elevation of the knee joint during knee flexion could also explain their findings. Sehat et al. demonstrated that the volume of blood in the suction drain 48 h following TKR was not an accurate measure of total blood loss, which was roughly double the drainage [4].

The purpose of this study was firstly to confirm that the simple, cheap method of flexing the knee not only reduced wound drainage but also total haemoglobin loss and secondly was to determine whether the reduction in wound drainage identified by Speck et al. [3] could be explained by elevation of the limb or obstruction of the drain.

Section snippets

Materials and methods

This study was approved by the local ethical committee and all patients in the trial were formally consented. Sixty consecutive patients undergoing primary unilateral total knee replacements for osteoarthritis between February and December 2000 were randomly allocated into three groups of 20 patients by sealed envelopes opened immediately after the operation. The number in each group was twice the number in each group reported by Speck et al. [3] to reduce the likelihood of a Type-II

Results

Patients’ age, sex and thromboprophylaxis were similar in all three groups (Table 1). The distribution of prosthesis type between the groups is summarised in Table 2. Groups 1 and 3 each had a single case of lateral release of the patella.

Discussion

The present study was unable to confirm the 33% reduction in wound drainage for the knee flexion group as reported by Speck et al. [3]. The knee flexion group showed only a 6% reduction in wound drainage, which was not statistically significant.

However, this study did show a reduction in total haemoglobin loss in the flexion and the elevation in extension groups compared with the extension only group. Both knee flexion and knee elevation in extension showed similar reduction in total

References (7)

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