Surface arthroplasty increases blood loss and transfusion requirement in comparison with conventional total hip replacement.

Abstract

Dear Sir, Total hip arthroplasty (THA) is a standard, successful treatment for symptomatic arthritic hips; it is a procedure that frequently requires intra- and post-operative blood transfusions1. With recent improvements in metal-on-metal bearing designs, surface replacement arthroplasty (SRA) has gained popularity, as it provides a substantial preservation of the proximal femoral anatomy. However, due to the minimal resection of the femoral head which reduces the access to the acetabulum remarkably, the procedure is technically demanding and wider surgical exposure is necessary. Consequently, blood requirements may be increased, but only a few direct comparisons of the two procedures have been published and with conflicting results2. The aim of this retrospective study was to compare the incidence of blood loss and transfusion requirement between two homogeneous series of patients undergoing either surface or standard cementless total hip arthroplasty. Forty-two consecutive hip resurfacing procedures performed from August 2004 to June 2009 were retrospectively reviewed and compared with a control group of 41 consecutive conventional stemmed THA performed over the same time period. Twenty-seven males and 12 females (3 were operated on bilaterally), aged from 27 to 72 years (median, 60 years), received a hybrid metal-on-metal resurfacing prosthesis. The control group, including 21 males and 18 females (2 with bilateral involvement), underwent primary cementless THA with ceramic-on-ceramic bearings. The median age of the population at operation was 67 years (range, 30 to 77 years). Bilateral surgery was performed as a staged procedure, with an interval of at least 1 year between operations. The indications for hip replacement were osteoarthritis (28 and 24 hips, respectively), avascular necrosis of the femoral head (7 and 8 cases), post-traumatic arthritis (3 and 1) and hip dysplasia (3 in both groups). Slipped capital femoral epiphysis was the reason for one resurfacing procedure, and rheumatoid arthritis and ankylosing spondylitis were respectively the initial diagnosis in four and one hips managed with conventional THA. Elective surgery was performed in patients who had failed non-operative treatment. Candidates for hip resurfacing were selected on the basis of age and activity level. They were, therefore, predominantly male (66.7%) and a median of 7 years younger than patients undergoing THA (60 years vs 67 years, respectively; P =0.002). The gender difference between the two groups was not statistically significant (P =0.23). No patient in either group had undergone previous hip surgery. All procedures were carried out with the patient in a supine position through an anterolateral Watson-Jones approach (Table I). Table I Patients’ demographics and baseline characteristics. Peri-operatively, specific haematological data were evaluated. The haemoglobin level was measured the day before surgery and immediately before discharge (day 4 or 5, post-operatively) in order to assess blood loss. Any blood transfusions administered were recorded for all patients, determining the overall transfusion requirement. Autologous or allogeneic blood transfusions were administered based on a clinical assessment of the patient, haemoglobin concentration and the presence of any comorbidities. At baseline, a significantly higher level of haemoglobin was measured in hip resurfacings (median 13.1 g/dL; range, 10.9–15.6 g/dL) than in conventional THA (median 12.5 g/dL; range, 10.4–15.2 g/dL) (P =0.02). However, no statistically significant difference remained at discharge: 10.2 g/dL (range, 7.6–12.2 g/dL) and 10.1 g/dL (range, 7.2–12.3 g/dL), respectively (P =0.72). A similar number of patients received blood transfusions following surface and conventional arthroplasty: 36 and 35, respectively. However, significantly more blood was transfused in the SRA group (median of 900 mL; range, 600–1,500 mL) than in the THA group (median 600 mL; range, 300–1,500 mL) (P =0.04) (Table II). Consequently, resurfacing procedures were associated with an increased perioperative blood loss in comparison with stemmed hip replacements, as also documented by the statistically significant difference (pre- and postoperative) haemoglobin concentration between the two groups (P =0.04). Table II Patients’ peri-operative data: type of anaesthetic and haematological parameters (Hb levels and transfusion requirement) in patients undergoing surface or conventional hip arthroplasty. Total hip arthroplasty is a highly successful surgical procedure for the treatment of end-stage hip disease, although it is usually associated with significant blood loss1. Hip resurfacing has gained wider support over the past decade with the development of more successful implants and improvements in manufacturing techniques and materials2. Recently, it has been reported that the clinical and radiographic outcomes of surface and conventional arthroplasties are comparable2. Hip resurfacing is often considered to be a more complicated surgical procedure than stemmed THA, requiring more extensive exposure which could lead to greater blood loss. Unfortunately, the rate of blood transfusions required for SRA has not been widely determined, and the results are controversial. There are currently only a few published data on clinical outcomes related to blood management derived from comparisons of traditional hip arthroplasty with the resurfacing technique. In a prospective, randomised study, Vendittoli et al.3 evaluated the early clinical results of 103 hips which were implanted with a hybrid metal-on-metal SRA and 102 hips managed with cementless metal-on-metal THA. The mean total blood loss was 524 mL (range, 100–2,200 mL) in the SRA group and 482 mL (range, 100–3,300 mL) in the THA group. The mean transfusion rate was 4.7% and 9.7%, respectively. However, no statistically significant differences were found between the two groups. Fowble et al.4 compared 50 consecutive metal-metal surface replacements in 50 patients with 44 consecutive conventional total hip arthroplasties in 35 patients. Hip resurfacing was associated with significantly less estimated surgical blood loss (P =0.005) and less post-operative drain output (P =0.05), resulting in significantly less total blood loss in the SRA group (719 mL for SRA, 971 mL for THA; difference 252 mL; P =0.0005) and fewer blood transfusions: 12/50 (24%) in the SRA group, 28/44 (64%) in the THA group (P <0.0001). A systematic review was undertaken by Smith et al.2 in 2010, evaluating the clinical and radiological outcomes of resurfacing procedures compared with stemmed arthroplasties in 46 studies (3,799 SRA and 3,282 THA). While the results indicated that there was a greater requirement for blood transfusion following THA (RR =0.4, 95% CI: 0.2 to 0.6; P <0.001), the difference seen with greater estimated blood loss with THA (MD = −152.8, 95% CI: −305.0 to −0.5; P <0.05) should be viewed with caution, given the high levels of statistical heterogeneity reported. The inadequacy of the available data prompted us to perform the present study. The increased requirement of blood transfusions following hip resurfacing (600 mL vs 900 mL; P =0.04), despite higher pre-operative levels of haemoglobin (13.1 g/dL vs 12.5 g/dL; P =0.02) documents the larger amount of blood loss among the patients undergoing SRA. This study has some limitations. It is retrospective and observational review, involving a small number of cases and the patients were not randomised, because the choice of the procedure was based on age and level of activity, but the two groups were closely matched for various other demographic factors. However, one of the strengths of the study was that all operations were performed by the same surgeon using exclusively an anterolateral approach. In conclusion, hip resurfacing is a bone-conserving reconstructive option for patients with severe articular damage, and newer generations devices have recently been shown to be a successful alternative to standard stemmed THA in young and active patients5. However, the limited femoral resection is associated with longer operative times and wider surgical exposure. Consequently, it should be considered that SRA may be associated with increased blood requirements. Further investigations including larger populations of patients are needed to confirm our findings definitively.