[Experience with the Hind Foot Relaxation Boot].

The goal of this paper is to report our experience with hindfoot fractures using our specially developed boot, with a follow-up of 557 cases. This boot works like the well-known Allgöwer-Röck ortheses (ARO), but is a hybrid between a boot and an orthesis. It allows full weightbearing without using crutches and completely protects an acutely operated hind foot fracture, hind foot arthrodesis or a hind foot fracture which is suitable for conservative treatment. In its first generation, this boot was custom made and used in 408 cases, from March 1999 to February 2011. This study was performed exclusively at the Department of Traumatology and Reconstructive Surgery in the University Centre of Orthopaedics and Traumatology, since 2013 at the Carl Gustav Carus University Hospital of the Technical University of Dresden (since 2013). The new improved second generation of this boot has been used in 149 patients between March 2011 and February 2016. This model is lighter and safer, due to an aluminium U-profile which is produced in one piece and interposed and fixed with 4 screws into the sole of the boot. The ground reaction forces are transported to the tibial head by this U-profile, to which the dorsal acryl shell for the calf of the Röck system is fixed with 2 screws on both sides, including the free ventral patellar shell. This is closed individually by two quick fastener buckles. This modular system of the second generation boot is now available for all patients in Dresden. These new boots have replaced the use of a wheel-chair for 3 months and are especially useful in bilateral calcaneus fractures - which occur in about 18% of all cases. In these new boots, the whole sole of the boot is in contact with the ground, rather than a surface of 9 × 3 cm as in the Allgöwer-Röck ortheses. As a result, these boots are considered to be superior to the ARO because standing and walking without crutches is much more easier - even for elderly patients. In contrast to the Allgöwer-Röck ortheses, in which no ground reaction forces are transmitted to the free hanging foot, some ground contact in the boot is provided through the metatarsal heads and toes, as the foot is positioned at about 20 degrees of equinus. Due to these conditions, osteopenia of the foot skeleton and deficits of coordination are less often observed clinically after 3 months than has been the case with the ARO. With the Allgöwer-Röck orthesis for only one injured hind foot, the leg length must be corrected by up to 8 to 10 cm for the contralateral shoe sole. On the contrary, this new boot facilitates free walking. In our series of a total number of 557 boots in 401 patients,156 patients wore two boots due to bilateral hindfoot fractures. The patients' mean age was 39.9 years (14 to 80 years), including 83.9% males. With application of low molecular weight heparin and lower leg compression hoses (primarily of the CCL1 type), there was no dislocation of the hindfoot fractures, no wound complication due to pressure in the boot and no deep vein thrombosis leg compression. The main indication for prescribing the boot was 252 bilateral calcaneal fractures. Whereas in the first generation fatigue fracture of the aluminium U-profile was found in 4 of 408 (0.9%) cases. There was only one such case in the second generation (n = 149). The boot was worn during the with the healing time of the fractures for a mean of 12.3 weeks in both groups.