Tibiotalocalcaneal Fusion with a Retrograde Triple Bending Nail - 2-Year-Followup Results

Abstract

Category: Hindfoot Introduction/Purpose: Retrograde nails are one option for fixation in tibiotalocalcaneal fusion (TTCF). Most actual designs include straight or distally lateral bent nails that could have a short bone purchase in the calcaneus with potentially limited stability and resulting delayed union or nonunion. A nail with additional distal posterior bend for longer purchase in the calcaneus for increased stability was developed (A3, Small Bone Innovation, Morrisville, PA, USA). The aim of this study was to investigate the clinical application and short-term clinical followup. Methods: In a prospective consecutive non-controlled clinical followup study, all patients with TTCF using A3 from October 18th, 2011 to April 29th, 2013 were analyzed. The specific shape of the nail includes a distal double bend; one posterior (15°) and one lateral (10°). Posterolateral approach to the ankle and subtalar joint were utilized. The times and accuracy of the alignment and implant position (Visual analogue scale, 0-10) for implant placement, complications, radiological fusion, and Visual Analogue Scale Foot and Ankle (VAS FA) were recorded. Time for implant position comprised placement of the nail, 4 locking screws and compression with the compression screw. Calcaneal pitch and hindfoot angles were measured, pre-, postoperatively and at 24 months. Fusion (≥50% bony bridge at ankle and subtalar joints assessed on radiographs) was assessed at 6, 9, 12 weeks, 12, 24 months. VAS FA was recorded at 24 months. Results: 66 cases/feet were included (age, 58.5 (22-80) years; VAS FA, 29.6 (0-69)). Indications were specified as follows (multiple indications possible): osteoarthritis, n=43 (65%); instability, n=12 (18%); deformity, n=36 (55%), failed total ankle replacement, n=4 (6%); failed previous fusion, n=9 (14%), diabetes mellitus, n=5 (8%). The time for implant preparation and positioning was 17.5 (5-31) minutes. The accuracy of alignment and implant position was 9.4 (7.5 - 10). Sixty (91%) patients completed follow-up: VAS FA 59.9 (t-test (comparison with preoperative scores), p=.01)), fusion rate 100%, high accuracy of correction and implant position. The deviation of the measured angles from the desired angles (hindfoot angle, 5° valgus; calcaneal pitch angle, 20°) were lower at follow-up than pre-operatively (each p < 0.001). Conclusion: TTCA with the A3 implant system showed accurate correction and implant position. Two-year-follow-up in 60 patients showed good clinical outcome scores and 100% fusion rate.