[Healing modalities in unstable tibial fractures treated by locked flexible intramedullary fixation]

This clinical study aimed specifically to evaluate the role of flexibility in aseptic consolidation of unstable tibial fractures on compact bones. The device employed was made of intramedular nails placed separately and locked together using an original proximal system.

125 unstable compact bone fractures of the tibial shaft were treated by this method for almost 6 years. 110 cases were included in this study. 30 per cent of the fractures were open. The topographical breakdown of fracture sites on the diaphysis was 6 times, in the upper third (Sector I), 23 times in Sector II and 66 times in the lower third (Sector III). In 13 cases, there were sequential fractures of which the upper site was in Sector I. 57 cases were simple sites (A), 27 were sites with edges greater than 50 per 100 of the diaphyseal circumference (B), and 26 per 100 of comminuted sites (C). The distance measured in the fracture sites after osteosynthesis were 66 times within 3 mm, 24 cases from 4 to 10 mm, 12 cases from 11 to 15 mm, and 8 cases over 16 mm.

110 cases were followed for more than 6 months. Consolidation was established on standard clinical and radiological criteria. The value of parameters affecting consolidation and the time period recorded were validated by a precise statistical evaluation using Stat. View II software, and Fisher and Yates tables.

Complications due to implants were rare and minor. There were only 4 cases of nonunion resulting from secondary desaxation of two pins apparatus. 16 cases of nonunion (14.5 per 100) were recorded but 3 were forseeable nonunions, because of a traumatic bone loss. 8 cases were Sector I fractures of which 7 were Sector I unsequental fractures. 7 cases had a gap of 10 to 15 mm, and 5 of 16 to 20 mm. Thus 42.1 per 100 of cases in Sector I were not consolidated compared to only 6.1 per 100 of cases in Sector III. Primary consolidation of the 94 cases was achieved in an average of 11.08 +/- 3.19 weeks (minimum 6 weeks, maximum 20 weeks). Time for consolidation did not appear to be affected by anatomical type, opened fracture (degree 1 or 2) nor number of nails used. But, there were significant differences according to topography and postoperative gap at the fracture site. Sector II fractures took 15 days less than Sector I fracture: average 10.5 as compared to 12.6 weeks. The cases with a gap of 0 to 3 mm consolidated at an average of 10.6 weeks, those with 4 to 10 mm: 11.39 weeks, with a gap of 11 to 15 mm: 14.4 weeks, and the cases superior to 16 mm: 14.8 weeks.

Compared to the interlocking nail, this procedure gave an average shortening of consolidation delay of 1 month for closed and degree 1 and 2 open fractures. This rapidity of consolidation can only be explained by the flexibility parameter. Thus it is only the flexibility of the device which can explain that even with a gap of 11 to 15 mm left within the fracture site, consolidation occurred 1 time out of 2 and 9 times out of 10 when the gap was 4 to 10 mm. Finally, this mechanical parameter can explain that consolidation is by far the shortest for low fractures although these are reputed to be the least osteogenic.