A comparison of two techniques for knee arthrodesis: the custom made intramedullary Mayday nail versus a monoaxial external fixator.

The most common indication for knee arthrodesis is pain and instability in an unreconstructable knee following an infected knee arthroplasty. In this study, we compare the use of the Mayday arthrodesis nail (Orthodynamics, Christchurch, UK) versus external fixation, Orthofix (Berkshire UK) and Stryker Hoffman II (County Cork, Ireland). All patients in this study underwent arthrodesis between 1995 and 2006 at Conquest Hospital, Hastings. In group A, 11 patients underwent arthrodesis with a Mayday nail. In all cases, the indications were infected total knee replacements (TKR). Three of these patients previously had failed attempts at arthrodesis with external fixation devices. In group B, seven patients underwent arthrodesis using external fixation. In six patients, the indication was infected TKRs. Results were reviewed retrospectively, with union assessed both clinically and radiologically. The mean inpatient stay for the Mayday nail group was 23 days (range 8-45 days) compared with 76 days (range 34-122) for the external fixation group (p<0.01, CI 95). Ten patients in group A went on to confirmed primary arthrodesis. One patient underwent revision arthrodesis with a Mayday nail and subsequently united. In group B only two patients achieved union. The rate of union was significantly greater in the Mayday nail group than the external fixation group (91% vs 29%, p<0.01). Of those patients that achieved union, there was no difference in the time to fusion between groups. Our study supported the existing literature and found that the Mayday nail appeared more effective than monoaxial external fixators for arthrodesis in the management of infected total knee replacements.