442 THE JOURNAL OF BONE AND JOINT SURGERY The blood flow to the femoral head/neck junction during resurfacing arthroplasty A COMPARISON OF TWO APPROACHES USING LASER DOPPLER FLOWMETRY H. W. Amarasekera, M. L. Costa, P. Foguet, S. J. Krikler, U. Prakash, D. R. Griffin From Warwick Medical School, Coventry, England  H. W. Amarasekera, MS, FRCS (Ed), Clinical Research Fellow  M. L. Costa, PhD, FRCS (Tr & Orth), Clinical Senior Lecturer  D. R. Griffin, MA, MPhil (Epid), FRCS (Tr&Orth), Professor of Trauma and Orthopaedic Surgery Clinical Sciences Institute University of Warwick Medical School, Clinical Sciences Building, University Hospital, Clifford Bridge Road, Coventry CV2 2DX, UK.  P. Foguet, LMC, FRCS (Orth), Consultant Orthopaedic Surgeon  S. J. Krikler, BSc, PhD, FRCS(Orth), Consultant Orthopaedic Surgeon  U. Prakash, FRCS(Orth), Consultant Orthopaedic Surgeon University Hospitals of Coventry and Warwickshire, Clifford Bridge Road, Coventry CV2 2DX, UK. Correspondence should be sent to Professor D. Griffin; e-mail: damian.griffin@warwick.ac.uk ©2008 British Editorial Society of Bone and Joint Surgery doi:10.1302/0301-620X.90B4. 20050 $2.00 J Bone Joint Surg [Br] 2008;90-B:442-5. Received 6 August 2007; Accepted after revision 21 December 2007 We used Laser Doppler flowmetry to measure the effect on the blood flow to the femoral head/neck junction of two surgical approaches during resurfacing arthroplasty. We studied 24 hips undergoing resurfacing arthroplasty for osteoarthritis. Of these, 12 had a posterior approach and 12 a trochanteric flip approach. A Laser probe was placed under radiological control in the superolateral part of the femoral head/neck junction. The Doppler flux was measured at stages of the operation and compared with the initial flux. In both groups the main fall in blood flow occurred during the initial exposure and capsulotomy of the hip joint. There was a greater reduction in blood flow with the posterior (40%) than with the trochanteric flip approach (11%). Resurfacing arthroplasty has become a common procedure for young people with severe arthritis of the hip joint. 1 Two important complications, fracture of the femoral neck and aseptic loosen- ing, may be associated with avascular necrosis (AVN) of the head of the femur owing to disrup- tion of the blood flow during surgery. 2 The reported incidence of fracture of the neck follow- ing resurfacing varies between 0% and 12%, 3 commonly being in the range of 0% to 2%. 1,4-6 Treacy et al 1 noted a low incidence of AVN fol- lowing resurfacing, but Milgram and Rana 7 found evidence of this in 20 of 32 failed resurfac- ing arthroplasties. The main blood supply to the femoral head comes from the ascending branches of the medial circumflex femoral artery, 8 poste- rior to the hip joint. 9,10 In a posterior approach to the hip these vessels may be damaged during dis- section of the obturator externus and quadratus femoris 11 and there is some evidence that the anterolateral approach leads to less disruption of blood flow. 12 Ganz et al 13 have described an alternative trochanteric flip approach that pre- serves these vessels during surgical dislocation of the hip, thus maintaining the blood supply. 1 We carried out this study to test the hypothesis that a trochanteric flip approach would disrupt the blood supply to the femoral head/neck junction less than the posterior approach during resurfac- ing arthroplasty. Patients and Methods A total of 24 consecutive patients who had a metal-on-metal resurfacing arthroplasty (Cor- met; Corin group, Cirencester, United King- dom) for primary osteoarthritis of the hip were included in the study. Of these, 12 had a poste- rior and 12 a trochanteric flip approach according to the preference of the surgeon. Five surgeons were included; three used the posterior approach and two the trochanteric flip approach. There were eight men and four women in the posterior group and seven men and five women in the trochanteric group. The mean age in the posterior group was 51 years (31 to 59) and in the trochanteric group 56 years (30 to 70). All patients had Kellgren and Lawrence 14 grade III osteoarthritis. The poste- rior group had six procedures on the left hip and six on the right, whereas the trochanteric flip group had three on the left and nine on the right. The mean operative time was 130 min- utes (115 to 150) for the posterior and 155 minutes (130 to 180) for the trochanteric flip approaches. All patients received general anaesthesia and were positioned in the lateral position. The skin incision was made according to the approach. After incision of the fascia lata, but before any further dissection was per- formed, a 2.0 mm drill was passed through the lateral femoral cortex into the superior part of the head/neck junction under fluoro- scopic guidance (Fig. 1). A Laser Doppler probe (Moor Instruments Ltd, Axminster, United Kingdom) was inserted through the drill hole until the tip reached the head/neck junction as confirmed radiologically. The