Additional femoral catheter in combination with popliteal catheter for analgesia after major ankle surgery.

BACKGROUND The contribution of the saphenous nerve in pain after major ankle surgery is unknown. The aim of this study was to evaluate its contribution in this context. METHODS Fifty patients were included in this prospective, randomized, controlled study. In all patients [Group P (popliteal) and Group F (popliteal+femoral)], a popliteal catheter was placed before operation and ropivacaine 0.5% (30 ml) administered via this catheter; major ankle surgery was then performed under spinal anaesthesia. In Group PF patients, an additional femoral catheter was sited before operation and ropivacaine 0.5% (10 ml) administered. Six hours after spinal anaesthesia (defined as T(0)), a continuous infusion of ropivacaine 0.3% (14 ml h(-1)) was started through the popliteal catheter until T(24). Then, the concentration was reduced to 0.2% until T(48). Patients in Group PF received continuous ropivacaine 0.2% (5 ml h(-1)) through the femoral catheter from T(0) to T(48). I.V. morphine patient-controlled analgesia was used as a rescue analgesia. Pain at rest, pain with movement, adverse effects, and i.v. morphine consumption were assessed. Pain at rest and on movement was evaluated 6 months after operation. RESULTS Pain at rest was comparable in the two groups. In Group PF, patients had significantly reduced pain during movement in the postoperative period (P=0.01) and 6 months after operation (P=0.03). Morphine consumption was significantly reduced in Group PF at T(0)-T(24) and T(24)-T(48) (P=0.01). Adverse effects were comparable in both groups. CONCLUSIONS The addition of continuous femoral catheter infusion of ropivacaine to a continuous popliteal catheter infusion improved postoperative analgesia during movement after major ankle surgery. This effect was still present 6 months after surgery.