Secondary nailing after external fixation for tibial shaft fracture: risk factors for union and infection. A 55 case series.

INTRODUCTION Secondary intramedullary nailing (SIN) following external fixation (EF) of tibial shaft fracture is controversial, notably due to the infection risk, which is not precisely known. The present study therefore analysed a continuous series of tibial shaft SIN, to determine (1) infection and union rates, and (2) whether 1-stage SIN associated to EF ablation increased the risk of infection. HYPOTHESIS Factors exist for union and onset of infection following tibial shaft SIN. MATERIALS AND METHODS A retrospective series of SIN performed between 1998 and 2012 in over 16-year-old patients with non-pathologic tibial shaft fracture was analysed. EF pin site infection was an exclusion criterion. Fractures were graded according to AO and Gustilo classifications. Study parameters were: time to SIN, 1- versus 2-stage procedure, bacteriologic results on reaming product, post-nailing onset of infection, and time to union. RESULTS Fifty-five patients (55 fractures) were included. There were 16 closed and 39 open fractures: 7 Gustilo type I, 26 type II and 6 type IIIA; 33 AO type A, 14 type B and 8 type C. Mean time to SIN was 9 ± 9.6 weeks (range, 4 days to 12 months). There were 23 1-stage procedures, and 32 two-stage procedures with a mean 12-day interval (range, 4-30 days). Twelve reaming samples were biologically positive without secondary infection. There were 4 septic complications (3 abscesses, 1 osteomyelitis), and 1 aseptic non-union required re-nailing. The union rate was 96%. The sole factor of poor prognosis was severity of fracture opening. One-stage SIN did not increase infection risk. DISCUSSION The present results were better than reported in the literature, where the rates of Gustilo IIIA and IIIB fracture and pin site infection are, however, higher. Tibial shaft SIN is a reliable procedure, with infection risk correlating with Gustilo type and time to surgery. Surgery should be early, before onset of EF pin site infection. A 1-stage attitude appears feasible in early SIN. LEVEL OF EVIDENCE Level IV. Retrospective study type.