Results of internal fixation of Pauwels type-3 vertical femoral neck fractures

Abstract

Background: It has been postulated that femoral neck fractures with a more vertical fracture line (i.e., a high Pauwels angle) may experience more shear forces and therefore may be predisposed to nonunion or loss of fixation. Although there is controversy regarding which fixation method is ideal, we are aware of no large clinical series in which the treatment outcomes of these fractures were evaluated. The purpose of this multicenter study was to evaluate a large consecutive series of high shear angle (>70 degrees) femoral neck fractures to learn more about the outcomes, complications, and performance of various internal fixation strategies.

Methods: Between January 1993 and January 2005, seventy-six Pauwels type-3 (Orthopaedic Trauma Association [OTA] type-31B2.3) femoral neck fractures were treated in seventy-five patients with a mean age of forty-two years. Fourteen patients were lost to follow-up. Sixty-two fractures in sixty-one patients were followed to union or revision surgery, with a mean duration of follow-up of twenty-four months. Thirty-seven fractures were treated with cannulated screws and twenty-five, with a fixed-angle device. The reduction quality, accuracy of implant placement, time to surgery, influence of capsular decompression, and rates of nonunion and osteonecrosis were evaluated.

Results: Fifty-nine (95%) of the fractures had good-to-excellent reduction, and three had a fair reduction. There was a nonunion of eight (14%) of the fifty-nine fractures with a good-to-excellent reduction and two of the three with a fair reduction. There was a septic nonunion of one fracture treated with a dynamic hip screw. There was an aseptic nonunion of seven (19%) of the thirty-seven fractures treated with screw fixation alone as compared with two (8%) of the twenty-five fractures treated with a fixed-angle device. Osteonecrosis occurred after treatment of seven (11%) of the sixty-two fractures.

Conclusions: Despite timely, excellent reduction and accurate implant placement in the vast majority of cases, the nonunion rate was 19% for fractures treated with cannulated screws alone and 8% for those treated with a fixed-angle device. Although these failure rates are not significantly different, we believe that this study documents the challenging nature of this fracture pattern and the ideal fixation device remains undefined.