PAPER 117: MAJOR COMPLICATIONS AFTER FEMORAL NERVE BLOCKS FOR KNEE REPLACEMENT: A CAUSE FOR CONCERN

Purpose: Multi-modal therapy remains the cornerstone of post-operative pain management following knee replacement surgery. Femoral nerve catheters and blocks have been used with success in the management of post-operative pain yet most practicing arthroplasty surgeons and anaesthesiologists are unaware of the potential complications and risks of the procedure. The purpose of this study is to report on the complications associated with these techniques following knee replacement surgery. Method: One thousand one hundred and ninety patients underwent knee replacement surgery between January 2004 and July 1, 2007 and received an indwelling continuous infusion femoral catheter for post-operative marcaine pump infusion. For the initial 469 patients (Group 1), the continuous infusion ran for 2 to 3 days. In 721 patients, the continuous infusion was discontinued 12 hours following surgery (Group 2). Results: There were 15 major complications observed in 1190 patients: 7 femoral nerve palsies (2 in Group 1, 5 in Group 2) and 8 falls (4 in each group). For the patients who had fallen in hospital, the injuries sustained were: traumatic hemarthrosis, hemarthrosis requiring arthrotomy, major wound dehiscence with exposed implants, complete medial collateral ligament rupture requiring repair, quadriceps tendon rupture requiring delayed repair, minor wound dehiscence with suture, and displaced ankle fracture. Conclusion: Femoral nerve catheters and blocks are effective tools for post-operative pain relief following knee arthroplasty surgery. However, it is important for the surgeon and anaesthesiologist to provide information regarding the potential complications of the treatment as part of an informed consent. Although the complication rate is relatively low at 1.3%, the occurrence of femoral nerve palsies as well as re-operations significantly delayed patient recovery. We did not observe a benefit in terms relative risk reduction with discontinuation of the continuous infusion 12 hours following surgery. The femoral palsies reported in our series have led our institution to adopt ultrasound guidance for catheter placement rather than tradition nerve stimulation technique, although the safety of this newer technique is currently under evaluation.