[Risk factors of pinhole infection in the fractured lower limbs after external fixation: a case-control study]

To investigate the risk factors of pinhole infection in the fractured lower limbs after external fixation.

The case-control study was designed. From May 2009 to May 2014, the clinical data of 272 patients with lower limb fracture treated by external fixation device were collected. All the patients were divided into two groups according to post-operative pinhole infection. There were 29 cases in the case group including 23 males and 6 females. The age of patients in case group ranged from 25 to 77 years old,with the average age of (53.41 ± 12.77) years old. There were 243 cases in control group including 217 males and 26 females. The age of patients in the control group ranged from 27 to 78 years old, with the average age of (48.71 ± 11.87) years old. There were nine risk factors observed in our study including age, gender, fixed time by external fixation device, diabetes, time in bed, smoking, operation condition of other parts in the body, infection condition of other parts in the body.

The results of univariate analysis showed that there were statistically significant differences among age (χ² = 15.708, P < 0.001), fixed time by external fixation device (χ² = 11.940, P < 0.001), severity of the lower limb fracture (χ² =15.438, P < 0.001), diabetes (χ² = 8.519, P = 0.004) and time in bed (χ² = 7.165, P = 0.007) between case group and control group. The results of Logistic regression analysis showed that the risk factors of pinhole infection after fixed by external fixation device in the lower limb fracture were the advanced age (OR = 8.327, P < 0.001), fixed time by external fixation device (OR = 6.795, P < 0.001), diabetes (OR = 4.965, P = 0.001) and time in bed (OR = 4.864, P = 0.008).

The advanced age, long fixed time, diabetes and long time in bed could increase the risk of pinhole infection after external fixation in the lower limbs with fracture.