Automated Continuous Distraction Osteogenesis May Allow Faster Distraction Rates: A Preliminary Study

Abstract

To determine if automated continuous distraction osteogenesis (DO) at rates faster than 1mm/day results in bone formation by clinical and radiographic criteria, in a minipig model. An automated, continuous, curvilinear distraction device was placed across a mandibular osteotomy in 10 minipigs. After 12 mm of distraction and 24 days of fixation, the animals were sacrificed and bone healing was evaluated. The continuous distraction rates were 1.5 mm/day (n= 5) and 3 mm/day (n= 5). A semiquantitative scale was used to assess the exvivo clinical appearance of the distraction gap (3= osteotomy not visible; 2= <50% visible; 1= >50% visible; 0= 100% visible), stability (3= no mobility; 2 and 1= mobility in 1 plane or 2 planes, respectively; 0= mobility in 3 planes), and radiographic density (4= 100% of gap opaque; 3= >75%; 2= 50% to 75%; 1= <50%; 0= radiolucent). Groups of 4 minipigs distracted discontinuously at 1, 2, and 4 mm/day served as controls. Automated, continuous DO at 1.5-mm/day and 3-mm/day had similar bone formation compared to discontinuous DO at 1-mm/day. The continuous DO 1.5-mm/day group had significantly higher scores for appearance and radiographic density compared with the discontinuous 4-mm/day group. The continuous DO 3-mm/day group had significantly higher scores for appearance and radiographic density compared with the discontinuous 4-mm/day group and greater stability compared with the discontinuous 2- and 4-mm/day groups. Results of this preliminary study indicate that continuous DO at rates of 1.5 and 3.0mm/day produces better bone formation compared with discontinuous DO at rates faster than 1 mm/day.