Yonsei Med J.  2013 May;54(3):803-805. 10.3349/ymj.2013.54.3.803.

False Femoral Neck Fracture Detected during Shaft Nailing: A Mach Band Effect

• Yang KH
• Kim S
• Jeong JD

• KMID: 1727903
• DOI: http://doi.org/10.3349/ymj.2013.54.3.803

Abstract

Femoral neck fractures are associated with femoral shaft fractures in 1% to 9% of cases. Undisplaced neck fractures are susceptible to displacement during shaft nailing. We report the case of a 57-year-old male patient in whom we performed standard intramedullary nailing for a femoral shaft fracture. In doing so, we identified a vertical radiolucent line at the femoral neck, which was thought to be further displacement of a hidden silent fracture or an iatrogenic fracture that developed during nail insertion. Consequently, we decided to switch to reconstructive femoral nailing. Postoperative hip imaging failed to show the femoral neck fracture that we saw in the operating room. Here, we discuss the aforementioned case and review the literature concerning this artifact.

Keyword

Pseudofracture; femur neck; nailing; mach band

MeSH Terms

*Artifacts
Femoral Fractures/diagnosis/*radiography/surgery
Femoral Neck Fractures/diagnosis/*radiography/surgery
Fracture Fixation, Intramedullary
Humans
Male
Middle Aged

Figure

• 

  Fig. 1 (A) A 3.2-mm guide pin was inserted at the tip of the greater trochanter; the radiolucent line was not visible at that time. Hemostatic forceps were used to control the external rotation of the proximal fragment.4 (B) A radiolucent line mimicking a femoral neck fracture was visible after nail insertion. (C) A reconstruction nail was inserted for fixation of the femoral neck and shaft fracture; the radiolucent line appeared to decrease in size after insertion of two 6.0-mm partially threaded cancellous screws into the femoral neck and head.

• 

  Fig. 2 (A) Postoperative fluoroscopic study failed to reveal the femoral neck fracture in various limb rotations. (B) A CT scan confirmed that the femoral neck was intact. (C) Reversal of the fluoroscopic image taken in the operating room showed a radiolucent line running from the femoral neck to the medial thigh (arrows).

Reference

1. Tornetta P 3rd, Kain MS, Creevy WR. Diagnosis of femoral neck fractures in patients with a femoral shaft fracture. Improvement with a standard protocol. J Bone Joint Surg Am. 2007. 89:39–43.

2. Riemer BL, Butterfield SL, Ray RL, Daffner RH. Clandestine femoral neck fractures with ipsilateral diaphyseal fractures. J Orthop Trauma. 1993. 7:443–449.

3. Yang KH, Han DY, Park HW, Kang HJ, Park JH. Fracture of the ipsilateral neck of the femur in shaft nailing. The role of CT in diagnosis. J Bone Joint Surg Br. 1998. 80:673–678.

4. Park J, Yang KH. Correction of malalignment in proximal femoral nailing--reduction technique of displaced proximal fragment. Injury. 2010. 41:634–638.

5. Daffner RH. Skeletal pseudofractures. Emerg Radiol. 1995. 2:96–104.