External fixation for arthrodesis of the knee and ankle

In a series of 74 knee and ankle arthrodeses the Vidal-Adrey quadrilateral mounting of the Hoffmann device was employed for arthrodesis of the knee in 50 cases. Union occurred in 80%. The union rate was highest (86.2%) when arthrodesis was attempted for infection after total knee arthroplasty. The complication rate was 24%. Most of the complications were related to pin sites. In eight patients knee arthrodesis was performed by multiplanar pin insertion and external fixation with either the Hoffmann or Fischer device; union occurred in all patients; pin site infection occurred in one. In 13 tibiotalar arthrodeses a modified quadrilateral frame was utilized, sparing the subtalar joint; union occurred in all of these cases. For tibiocalcaneal arthrodesis, attempted in five patients, a triangular mounting based on pins placed through the tibia, calcaneus, and metatarsals was necessary. Union occurred primarily in four of the five patients. This study indicates the superiority of multiplanar pin insertion for knee arthrodesis for treatment of failed total knee arthroplasty. The use of larger pins manufactured from relatively nonreactive metal alloys seems to decrease the incidence of pin site problems.