VOL. 92-B, No. 1, JANUARY 2010 51 Measurement of joint effusion and haematoma formation by ultrasound in assessing the effectiveness of drains after total knee replacement A PROSPECTIVE RANDOMISED STUDY D. Omonbude, M. A. El Masry, P. J. O’Connor, A. J. Grainger, V. L. Allgar, S. J. Calder From Chapel Allerton Hospital, Leeds, England  D. Omonbude, FRCS(Orth), Specialist Registrar 41 Meadowbrook Court, Leeds LS27 0LG, UK.  M. A. El Masry, MSc, MRCS, Specialist Registrar  P. J. O’Connor, FRCR, Consultant Musculoskeletal Radiologist  A. J. Grainger, FRCR, Consultant Musculoskeletal Radiologist  S. J. Calder, MD, FRCS(Orth), Consultant Orthopaedic Surgeon Chapel Allerton Hospital, Leeds Teaching Hospital NHS Trust, Harehills Lane, Leeds LS7 4SA, UK.  V. L. Allgar, BSc, PhD, Senior Lecturer Hull and York Medical School, University of York, Hull HU6 7RX, UK. Correspondence should be sent to Mr D. Omonbude; e-mail: omonbude@yahoo.com ©2010 British Editorial Society of Bone and Joint Surgery doi:10.1302/0301-620X.92B1. 22121 $2.00 J Bone Joint Surg [Br] 2010;92-B:51-5. Received 27 November 2008; Accepted after revision 27 August 2009 We prospectively randomised 78 patients into two groups, ‘drains’ or ‘no drains’ to assess the effectiveness of suction drains in reducing haematoma and effusion in the joint and its effect on wound healing after total knee replacement. Ultrasound was used to measure the formation of haematoma and effusion on the fourth post-operative day. This was a semi- quantitative assessment of volume estimation. There was no difference in the mean effusion between the groups (5.91 mm in the drain group versus 6.08 mm in the no-drain, p = 0.82). The mean amount of haematoma in the no-drain group was greater (11.07 mm versus 8.41 mm, p = 0.03). However, this was not clinically significant judged by the lack of difference in the mean reduction in the post-operative haemoglobin between the groups (drain group 3.4 g/dl; no-drain group 3.0 g/dl, p = 0.38). There were no cases of wound infection or problems with wound healing at six weeks in any patient. Our findings indicate that drains do not reduce joint effusion but do reduce haematoma formation. They have no effect on wound healing. Surgical drains theoretically reduce the post- operative collection of fluid such as blood in a closed space. It is thought that blood collecting in the knee after total knee replacement (TKR) could impair wound healing, increase the risk of deep infection, and cause pain and stiffness with resultant delay in rehabilitation and extended hospital stay. 1 Haematomas form whether or not a drain is present, 2,3 and closed suction drains continue to be used following TKR. 4 This might be due to conflicting reports in observational studies on the use of closed suction drains. 1,5 Latterly there have been a number of studies questioning the use of drains after TKR. 6-8 Parker et al, 6 in a meta-analysis of randomised studies, concluded that the routine use of closed suction drains for elective hip and knee replacement may not be benefi- cial as patients required more transfused blood. Most of these studies have measured various indirect parameters, including the levels of hae- moglobin, the number of dressings required and the requirements for transfusion to assess the effectiveness of closed suction drainage. 9-11 We are not aware of any studies that have objectively measured the amount of residual haematoma and effusion or swelling in knees after TKR. In this study we used ultrasound to estimate the effectiveness of closed suction drains in reducing residual swelling in the knee joint and their influence on wound healing, after TKR, comparing patients in whom drains had been used to those without. Patients and Methods Between May 2006 and March 2007 a total of 85 patients with primary osteoarthritis of the knee, undergoing cemented TKR, were pro- spectively randomised into two groups: drain or no drain. Formal ethical approval was obtained and informed consent supplied. In the drain group patients received two deep drains. Sealed envelopes containing a card produced by computerised random number generation stating drains or no drains were opened imme- diately prior to suturing the quadriceps tendon. Patients with inflammatory arthropathy, revi- sion TKR and those having bilateral TKR were excluded from the study. Patients requiring complex primary procedures, valgus mal- alignment > 15° and patients on anticoagulants were also excluded. All the TKRs were carried out by the senior author (SJC). Seven patients could not be included in the study; in two, post-operative cardiac and respi- ratory problems arose which required admis- sion to intensive care units in another hospital, making ultrasound assessment impossible. Five patients were erroneously discharged