The characteristics and influence of iatrogenic fracture comminution following antegrade interlocking nailing for simple femoral shaft fractures, a retrospective cohort study

Abstract

Aim: The incidence and characteristics of iatrogenic comminution (IC) are unknown, and the influence of IC on fracture union is unclear. This study was aimed to investigate the (1) incidence and characteristics of IC and (2) the outcomes of IC following antegrade interlocking nailing of simple femoral shaft fractures.

Methods: We retrospectively collected data on patients who experienced simple femoral shaft fractures and underwent antegrade interlocking nailing between February 2009 and December 2016. The incidence and characteristics of IC were examined. According to the presence of IC, patients were divided into two groups: an IC group and a non-IC (NIC) group. Demographic information and nonunion rates were compared between the two groups. Potential risk factors for IC (age, gender, body mass index (BMI), nail fit ratio, reduction technique, and greater trochanter nail entry) were analyzed using univariate and multivariate logistic regression. The aforementioned variables, along with IC occurrence, were also assessed as potential risk factors for nonunion at 12 and 24 months after operation using multivariate logistic regression.

Results: Of the 211 total patients, IC occurred in 20.9% (n = 44) of patients. Most ICs were found at the level of the isthmus, and involved the medial cortex. Compared with the NIC group, higher nonunion rates were observed in the IC group at 12 months (31.8% vs. 12.5%, p = 0.002) and 24 months (18% vs. 6.5%, p = 0.017) after surgery. Age older than 35 years old was related with the occurrence of IC in univariate analysis. Multivariate analysis found no risk factor associated with IC. Open reduction technique, IC occurrence and higher BMI were identified as the risk factors of nonunion at 12 months and 24 months after surgery in multivariate analysis.

Conclusion: IC is a non-rare complication in antegrade interlocking nailing of simple femoral shaft fractures and was associated with higher nonunion rate. Age older than 35 years old showed a trend toward increasing risk of iatrogenic fracture comminution. In multivariate analysis, open reduction technique, IC occurrence and higher BMI significantly correlated with fracture nonunion.

Level of evidence: Level IV.

Keywords: Femoral shaft fracture; Iatrogenic fracture comminution; Incidence; Nonunion.

Fig. 1

A A preoperative plain film of a transverse femoral shaft fracture, B a postoperative plain film with iatrogenic fracture comminution involving the medial cortex with proximal extension, C a preoperative plain film of a transverse femoral shaft fracture, D a postoperative plain film with iatrogenic fracture comminution involving the lateral cortex with distal extension, E a preoperative plain film of an oblique femoral shaft fracture, F a postoperative plain film showing iatrogenic fracture comminution involving the medial cortex with both proximal and distal extension

Fig. 2

A A preoperative plain film of a transverse femoral shaft fracture, B a postoperative plain film showing an iatrogenic fracture comminution involving the medial cortex with proximal extension, C a preoperative plain film of a transverse femoral shaft fracture, D a postoperative plain film showing iatrogenic fracture comminution involving the lateral cortex with distal extension, E a preoperative plain film of a transverse femoral shaft fracture, F a postoperative plain film showing iatrogenic fracture comminution involving the anterior cortex with proximal extension

Fig. 3

Flowchart depicting the inclusion and exclusion criteria and the number of patients enrolled in this study

Fig. 4

A A case of a 34-year-old man who suffered from right femoral shaft fracture after motor vehicle accident. B Iatrogenic fracture comminution over medial cortex which extended distally was noticed after surgery of open reduction and internal fixation. C At 14 months postoperatively, the fragment of iatrogenic comminution healed. However, the main fracture site remained nonunion. D The proximal locking screw was removed for dynamization at 17 months postoperatively. Partial union was noticed 6 months after dynamization