Abstract
Patellofemoral complications following knee arthroplasty are a wellโknown problem. Patellar ischemia has been suspected to be causative for fracture, anterior knee pain, and patella component failure. The purpose of this study was to assess the influence of knee arthroplasty surgical dissection on patellar blood flow. Patellar blood flow was measured by means of intraosseous laser Doppler flowmetry (LDF) in 10 patients undergoing total knee arthroplasty by a standard medial parapatellar approach. The initial blood flow was 121.6โยฑโ114.7 AU. The signal significantly decreased by 71% (pโ=โ0.0051) when the knee was flexed and lost the pulsatile signal pattern in 80%. After arthrotomy, the signal was 100.1โยฑโ120.3 AU in extension. The lowest signal was found in flexion and eversion of the patella (mean, 18โยฑโ10.7 AU) and all signals lost pulsatility. As compared to the initial values, completion of the soft tissue dissection did not lead to a significant change of the blood flow signal (121.3โยฑโ104.8; pโ=โ0.6835). Flexion of the knee joint markedly reduced patellar perfusion. Standard medial parapatellar approach did not significantly change patellar blood flow. This study does not support the theory of postoperative patellar ischemia as a cause of anterior knee pain or patellofemoral problems. ยฉ 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1389โ1394, 2007