Aims. The aim of this study was to determine the impact of the severity of anaemia on postoperative complications following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Methods. A retrospective cohort study was conducted using the American College of Surgeons National Quality Improvement Program (ACS-NSQIP) database. All patients who underwent primary TKA or THA between January 2012 and December 2017 were identified and stratified based upon hematocrit level. In this analysis, we defined anaemia as packed cell volume (Hct) < 36% for women and < 39% for men, and further stratified anaemia as mild anaemia (Hct 33% to 36% for women, Hct 33% to 39% for men), and moderate to severe (Hct < 33% for both men and women). Univariate and multivariate analyses were used to evaluate the incidence of multiple adverse events within 30 days of arthroplasty. Results. Following adjustment, patients in the THA cohort with moderate to severe anaemia had an increased odds of 6.194 (95% confidence interval (CI) 5.679 to 6.756; p < 0.001) for developing any postoperative complication. Following adjustment, patients in the TKA cohort with moderate to severe anaemia had an increased odds of 5.186 (95% CI 4.811 to 5.590; p < 0.001) for developing any postoperative complication. Among both cohorts, as severity increased, there was an increased risk of postoperative complications. Conclusion. Preoperative anaemia is a risk factor for complications following primary arthroplasty. There is a significant relationship between the severity of anaemia and the odds of postoperative complications. Patients who had moderate to severe anaemia were at increased risk of developing postoperative complications relative to patients with mild anaemia. When considering elective primary THA or TKA in a moderately or severely anaemic patient, surgeons should strongly consider correcting anaemia prior to surgery if possible. Cite this article: Bone Joint J 2020;102-B(4):485–494

Clinical, haematological or economic benefits of post-operative blood salvage with autologous blood re-transfusion have yet to be clearly demonstrated for primary total hip replacement. We performed a prospective randomised study to analyse differences in postoperative haemoglobin levels and homologous blood requirements in two groups of patients undergoing primary total hip replacement.

A series of 158 patients was studied. In one group two vacuum drains were used and in the other the ABTrans autologous retransfusion system. A total of 58 patients (76%) in the re-transfusion group received autologous blood. There was no significant difference in the mean post-operative haemoglobin levels in the two groups. There were, however, significantly fewer patients with post-operative haemoglobin values less than 9.0 g/dl and significantly fewer patients who required transfusion of homologous blood in the re-transfusion group. There was also a small overall cost saving in this group.

We prospectively audited 79 patients undergoing primary knee or hip arthroplasty (38 knees, 41 hips) and found that 66% (58% of knees, 73% of hips) had at least one unit of blood transfused postoperatively, with a mean transfusion requirement of 1.3 units per patient (1.1 for knees, 0 to 6; 1.5 for hips, 0 to 4). We then established a new protocol for postoperative blood transfusion. This requires the calculation of the maximum allowable blood loss (MABL) that each individual patient can safely lose based upon their weight and preoperative haematocrit. The total blood loss up to this volume is replaced with colloid. When a patient’s total blood loss reaches their MABL their haematocrit is measured at the bedside using the Microspin system (Bayer plc, Newbury, UK). If their haematocrit is low (< 0.30 for men, < 0.27 for women), blood is transfused. As a safety net all patients have their haemoglobin formally checked on days 1, 2, and 3 after surgery and have a transfusion if the haemoglobin levels are less than 8.5 g/dl. We conducted a further audit of 82 patients (35 knees, 47 hips) after the introduction of this protocol. Under the new protocol only 24% of patients required blood (11% of knees, 34% of hips) with a mean transfusion requirement of 0.56 units per patient (0.26 for knees, 0 to 4; 0.79 for hips, 0 to 4). The use of clinical audit and the introduction of strict guidelines for transfusion can change transfusion practice and result in improved patient care. Our transfusion protocol is a simple and effective method of keeping transfusion to a minimum and is particularly useful in departments which do not have the facility to use autologous blood or reinfusion drains for elective orthopaedic surgery