Archives of Orthopaedic and Trauma Surgery (2018) 138:339–349
The nail–shaft-axis of the of proximal femoral nail antirotation
(PFNA) is an important prognostic factor in the operative treatment
of intertrochanteric fractures
· Katja Boernert
· Reto Babst
· Frank J. P. Beeres
· Björn‑Christian Link
Received: 7 November 2017 / Published online: 18 December 2017
© Springer-Verlag GmbH Germany, part of Springer Nature 2017
Introduction Due to the world’s aging population, intertrochanteric fractures are frequent. Considering age and comorbidi-
ties of most of these patients, it is indispensable to enable early postoperative mobilization of these patients. Intramedul-
lary osteosynthesis with PFN-A is widely used and, in general, considered safe and reliable for the operative treatment of
intertrochanteric fractures. However, implant -related complications are reported in 6–21% of all cases. In this study, we are
analyzing complication rates and risk factors for implant-related complications.
Materials and methods All intertrochanteric fractures admitted to our hospital and treated with PFN-A between January 2012
and January 2016 were analysed retrospectively. Radiological analyses of the CCD and the lateral oﬀset on the uninjured side
was compared to the CCD initially postoperatively and during follow-up on the operated side. Furthermore, we analysed the
tip-apex distance (TAD), blade position in the femoral head and introduced the nail–shaft axis as a new parameter.
Results Within 101 intertrochanteric fractures included, 16 implant-related complications were encountered (15.84%).
Analyses of risk factors for secondary varus displacement of greater than 10° within the follow-up and thus risk for cut-out
in the osteosynthesis revealed that etasblished risk factors such as a TAD > 25 mm, reduction in varus and an improper posi-
tion of the blade were also signiﬁcant risk factors in our cohort for failure of the osteosynthesis. Moreover, we introduced the
nail–shaft axis a new potential risk factor and could show that a too medial or too lateral nail–shaft axis is also signiﬁcantly
associated with secondary varus displacement.
Conclusion When treating introchanteric fractures with PFNA reduction in neutral or even slight valgus, aiming for a
TAD < 25 mm and a correct position of the blade within the femoral head reduced the risk for secondary varus displacement
signiﬁcantly. Furthermore, we suggest to aim for a central nail–shaft axis.
Keywords Intertrochanteric fracture · Proximal femoral nail · Varus displacement · Risk factor · Cut-out
The incidence of intertrochanteric fracture is increasing
due to the world’s aging population . Generally, patients
are operated unless there are contraindications for surgery.
Depending on the fracture morphology, these fractures are
either treated by a proximal femoral nail [2, 3], a sliding hip
screw with or without side plate , or an arthroplasty [5,
6]. For unstable fractures, nailing is often being considered
as the gold standard due to its superior stability . Despite
its common use and good clinical results, varus displace-
ment with cut out of the sliding screw remains a clinical
challenge. Varus displacement has been reported to occur in
6.5–21.2% of the cases [2, 8]. Risk factors for ﬁxation failure
including tip-apex distance (TAD) > 25 mm , improper
location of the blade , or a too lateral entry point [11–13]
have been described as possible causes. Although there are
multiple studies looking at risk factors for implant failure
in intertrochanteric fractures, interactions and emphases of
these factors are not fully understood. However, appreciation
of failure is a prerequisite to optimize clinical outcome in a
Chittawee Jiamton and Katja Boernert contributed equally.
* Björn-Christian Link
Department of Orthopaedics, Lerdsin Hospital, Bangkok,
Department of Orthopaedic and Trauma Surgery, Luzerner
Kantonsspital, 6000 Luzern, Switzerland