Effects of Dynamization with an Interlocking Femur Nail: A Clinical Study

Abstract

A consecutive, retrospective series of 179 patients with femoral shaft fractures that had been treated by a static interlocking nail was analyzed to determine the rate of union and the time to union in cases of planned conversion from static to dynamic fixation. The results were compared to those obtained with static fixation without dynamization. The dynamized group included 75 patients (12 females and 63 males). There were 62 closed fractures, five type I, and eight type II open fractures. According to the AO classification, 21 fractures were type 32.A (7, 32.A1; 6, 32.A2; 8, 32.A3), 33 were type 32.B (14, 32.B1; 7, 32.B2; 12, 32.B3), and 21 were type 32.C (9, 32.C1; 4, 32.C2; 8, 32.C3). The static group included 104 patients (27 females and 77 males). There were 90 closed fractures, 11 type I, and three type II open fractures. In this group, 47 fractures were type 32.A (11, 32.A1; 14, 32.A2; 2, 32.A3), 42 were type 32.B (10, 32.B1; 20, 32.B2; 12, 32.B3), and 15 were type 32.C (6, 32.C1; 3, 32.C2; 6, 32.C3). The 75 fractures that were dynamized united during an average time of 126 days while those of the static group took 103 days (p = 0.005). Considering single types of fractures, the time to union was significantly shorter in 32.A3 (p = 0.005), 32.B2 (p = 0.005) and 32.B3 (p = 0.004) fractures when dynamization was not performed. In the 32.C group, healing was shorter in the dynamized group for subgroups 32.C1 and 32.C2, without statistical significance. Thus, the static interlocking nail does not inhibit healing in 32.A and 32.B types of fractures, and the average time to union is shorter than in the dynamized group. Conversion to dynamic intramedullary fixation is not routinely necessary but needs to be performed when a persistent gap can interfere with the consolidation process.

Key words

femur - intramedullary - Grosse-Kempf - osteosynthesis - dynamization

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