Patient Function following Femoral Neck Shortening and Varus Collapse after Cancellous Screw Fixation of Isolated Femoral Neck Fractures: A Multicenter Cohort Study
Michael Zlowodzki, MD (a-Osteosynthesis and Trauma Care Foundation; AO North America); Ole Brink, MD, PhD (n); Julie Switzer, MD (n); Scott Wingerter, MD (n);
James Woodall Jr, MD (n); David R. Bruinsma (n); Brad A. Petrisor, MD (n);
Philip J. Kregor MD (n); Mohit Bhandari, MD, MSc (n);
University of Minnesota, Minneapolis, Minnesota, USA
Purpose: Femoral neck fracture collapse and shortening has been a desired effect of parallel screw fixation to promote healing; however, it might lead to femoral neck shortening. We aimed to evaluate the effect of shortening and varus collapse after cancellous screw fixation of femoral neck fractures on patient functional status and quality of life.
Methods: The databases of four university hospitals were screened to identify patients with a healed isolated femoral neck fracture. Patients were contacted by telephone to complete Short Form-36 (SF-36) and Euroquol-5D (EQ5D) questionnaires (primary outcome: SF-36 physical functioning score [PF]). Femoral neck shortening and varus collapse were assessed by three independent reviewers blinded to functional outcome results based on the latest follow-up radiographs and categorized into three grades: none/mild (within 5 mm/5 degrees), moderate (5-10 mm/5-10 degrees), and severe (>10 mm/>10 degrees). The minimal clinically important difference for SF-36 PF score equals 12 points (1/2 of standard deviation).
Results: 70 patients with an average follow-up of 20 months and an average age of 71 years were included in the study. Patients with severe shortening of their hip had significantly lower SF-36 physical functioning scores (no/mild shortening vs severe: 74 vs 42 points, P = 0.01). Similar important effects occurred with moderate shortening suggesting a gradient effect (no/mild shortening vs moderate: 74 vs 53 points). Some degree of varus collapse occurred in 39% of the patients and correlated moderately with the occurrence of shortening (r = 0.66, P <0.001). Shortening also resulted in lower EQ5D index scores (P = 0.05). In a regression analysis femoral neck shortening was the only significant variable predictive of a poor SF-36 PF score (P <0.001).
Conclusion and Significance: A large proportion of displaced and undisplaced femoral neck fractures fixed with cancellous screws heal in a shortened position (66%) and varus (39%). The differences in function we observed represent patient-important declines and suggest that uncontrolled sliding with cancellous screw fixation has limitations.
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• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing.