Background The depth of bolt in Femoral neck system (FNS, DePuy Synthes, Oberdorf, Switzerland) is difficult to finely control as the length of the bolt is in units of 5 mm. Thus, this study introduces a method to control the depth of FNS bolt in analogue scale in patients with femoral neck fracture. Methods By the technique of control of reaming and retraction of bolt, the tip of implant could be positioned close to subchondral bone without harming it. The position of implant tip in four cases in which the introduced technique was applied was compared to that of eight cases where the standard technique was performed. Results The average tip-apex distance measured in the cases that underwent surgery using the suggested technique in this study was statistically significantly shorter than that measured in the cases that underwent surgery under manufacturer guidelines. Conclusion Even though the bolt of FNS is manufactured in the unit of 5 mm, the technique proposed in this study helps surgeons to adjust the depth of bolt for the fixation of femoral neck fracture using FNS.

Breakage of the intramedullary nail is a rare complication after proximal femoral nail antirotation (PFNA) in intertrochanteric fracture treatment. The purpose of this study was (1) to investigate the frequency of nail breakage among the patients who were treated for mechanical failure after PFNA for intertrochanteric/pertrochanteric fracture, and (2) to determine the risk factors for nail breakage in PFNA treatment of intertrochanteric fracture.To identify mechanical failure after internal fixation using PFNA, we retrospectively reviewed the data of 35 patients (35 hips) who required reoperation after PFNA with a helical blade for intertrochanteric/pertrochanteric fracture between June 2005 and June 2018.We evaluated the frequency of breakage of PFNA and compared the demographic and radiologic parameters between the breakage and control (non-breakage) groups. We also compared the lever arm for the load of stress from the fulcrum according to the centrum-collum-diaphyseal (CCD) angle of blade by using reverse design technique.Among the 25 patients with mechanical failure after PFNA except 10 patients with peri-implant infection and osteonecrosis, 7 (28.0%) showed breakage of PFNA at average of 8 months (range, 5-13 months) after index surgery. A larger horizontal offset (the horizontal distance from the lateral surface of the IM nail and the medial tip of helical blade) was associated with an increased risk of nail breakage. A CCD angle of 130°has a shorter lever arm for the load of stress from the fulcrum, meaning a higher stress for nail breakage, although there was no association between CCD angle and breakage of the nail.Our study suggested that higher horizontal offset and a higher CCD angle can increase the risk of breakage of the PFNA nail at the aperture for the helical blade.

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Background: The depth of bolt in Femoral neck system (FNS, DePuy Synthes, Oberdorf, Switzerland) is difficult to finely control as the length of the bolt is in units of 5 mm. Thus, this study introduces a method to control the depth of FNS bolt in analogue scale in patients with femoral neck fracture. Methods: By the technique of control of reaming and retraction of bolt, the tip of implant could be positioned close to subchondral bone without harming it. The position of implant tip in four cases who was operated with the introduced technique was compared to that of eight cases with standard technique.Results: The average tip-apex distance measured in the group that underwent surgery with the technique suggested in this study was statistically significantly shorter than that in manufacturer guide group (p<0.05). Conclusion: Even though the bolt of FNS is manufactured in the unit of 5 mm, the technique proposed in this study helps surgeons to adjust the depth of bolt for the fixation of femoral neck fracture using FNS.

Background: Breakage of the intramedullary nail is a rare complication after proximal femoral nail antirotation (PFNA) in intertrochanteric fracture treatment. The purpose of this study was (1) to investigate the frequency of nail breakage among the patients who were treated for mechanical failure after PFNA for intertrochanteric/ pertrochanteric fracture, and (2) to determine the risk factors for nail breakage in PFNA treatment of intertrochanteric fracture.Methods: To identify mechanical failure after internal fixation using PFNA, we retrospectively reviewed the data of 35 patients (35 hips) who required reoperation after PFNA with a helical blade for intertrochanteric/ pertrochanteric fracture between June 2005 and June 2018. We evaluated the frequency of breakage of PFNA and compared the demographic and radiologic parameters between the breakage and control (non-breakage) groups. We also compared the lever arm for the load of stress from the fulcrum according to the centrum-collum-diaphyseal (CCD) angle of blade by using reverse design technique.Results: Among the 25 patients with mechanical failure after PFNA except 10 patients with peri-implant infection and osteonecrosis, 7 (28.0%) showed breakage of PFNA at average of 8 months (range, 5 to 13 months) after index surgery. A larger horizontal offset (the horizontal distance from the lateral surface of the IM nail and the medial tip of helical blade) was associated with an increased risk of nail breakage. A CCD angle of 130° has a shorter lever arm for the load of stress from the fulcrum, meaning a higher stress for nail breakage, although there was no association between centrum-collum-diaphyseal (CCD) angle and breakage of the nail.Conclusions: Our study suggested that higher horizontal offset and a higher CCD angle can increase the risk of breakage of the PFNA nail at the aperture for the helical blade.Levels of Evidence: Level III