Locked plates confer angular stability across fusion sites, and as such are more rigid than either screws or intramedullary nails. This gives the advantage of reducing motion to enhance union rates and potentially allowing early weight bearing. The Philos plate (Synthes) is a contoured locking plate designed to fix humeral fractures but which also fits the shape of the hindfoot and provides strong low profile fixation. Its successful use for tibiotalocalcaneal (TTC) arthrodesis has been reported.

Our aim was to prospectively evaluate the use of the Philos plate in hindfoot arthrodesis Twenty-one hindfoot arthrodeses were performed using the Philos plate between Oct 2008 and Jan 2010. Patients were followed up for a minimum of 1 year and had preoperative and 6 monthly AOFAS hindfoot scores and serial radiographs until union. Overall there were 15 ankle fusions, 5 tibiotalocalcaneal fusions and 1 subtalar fusion. At 6 months there were 13 unions and 9 non-unions (4 ankle, 5 TTC) giving a non-union rate of 38% overall and 25% for ankle fusions in isolation. Mean AOFAS scores at 6 months were 74/100 for the union group and 47 for non-unions (chi squared p < 0.001). No patient in the non-union group went on to fuse within a year without further surgery. Both groups had similar case mixes including osteoarthritis, AVN of the talus and failed arthroplasty. They also had similar co-morbidities, rates of smokers and bone grafting.

Our conclusion is that the high non-union rates are probably due to the lack of compression conferred across the join by the Philos plate as there is no compression hole and we did not supplement the fixation with a lag screw. We recommend using locked plates for hindfoot arthrodesis only with additional compression.