The Circular Arc Curved Nail for Internal Fixation of Tibio-Talo-Calcaneal Arthrodesis

Abstract

Category:Ankle; Ankle Arthritis; Diabetes; Hindfoot; TraumaIntroduction/Purpose:Normal anatomy demonstrates alignment of the heel, the subtalar facet, the talus, the ankle joint and the distal tibia on a regular curve. This curve lies on a vertical plane which is slightly angulated inwards in relation to the sagittal plane. Today's hindfoot nails are either straight or bent. The hole which accommodates the implant is always straight and thus does not respect the normal alignment of the hindfoot. This technique may cause a plantar neurapraxia, the nail holds poorly the calcaneus and tends to create a hindfoot varus. Purpose of the study is to optimize the technique toMethods:A circular arc bore hole crosses the heel, the posterior subtalar facet, the tibio-talar joint and the distal tibia metaphysis. The hole is bored using a motor driven end cutting flexible reamer which is seated within a rigid curved hull. The nail has the exact same shape than the hull and is impacted up to the distal tibia creating a bone-nail form fit. A distal locking screw crossing the subtalar joint and a proximal locking screw within the tibia concludes the central fixation. 47 patients (23 women and 24 men aging 30 to 84 y (mean 52y)) have been treated so far using this technique. The diagnosis was basically primary and post- traumatic arthritis and includes diabetic arthropathies (4 cases) and failed TAR (3 cases). After 2 weeks our patients did practise partial weight bearing using a cam walker for other 6 weeks.Results:The mean follow-up time of the patient series is 3 years (16-78 months). Two patients with diabetic arthropathy died 2 years and 8 months and the other 8 months post-op after consolidation of the arthrodesis due to their primary disease. 3 cases sustained a deep infection which requested a below knee amputation in 2 cases and a calcanectomy in another case. Within the remaining 42 cases, 37 consolidated their arthrodesis within 2 months; 5 cases had a delayed union and 2 cases had to be revised for a non-union, one in the ankle, the other one in the subtalar joint. Patients with a good bone quality and anatomical hindfoot axes could bear their body weight entirely at 2 months. 1 patient reported remaining pain at 2 years post-op and another case was additionally operated to correct a remaining midfoot deformity (club foot).Conclusion:The tibio-talo-calcaneal arthrodesis can be successfully treated using a central circular arc curved nail respecting a form fit interaction between bone and nail. The anatomical osteo-articular alignment of the hindfoot is corrected or preserved. Due to the safe approaches and the bone-nail form fit, the technique allows for primary stability and prevents shortcomings such as neurological complications and non-union. We expect a shorter period between surgical fixation and full weight bearing.