Purpose: Femoral neck fracture collapse and shortening has been a desired effect of parallel screw fixation to promote healing. While some degree of compression might be beneficial, it remains unknown whether the effects of uncontrolled femoral neck shortening leads to detectable functional impairment. 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.

Method: 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(SF36) and Euroquol-5D(EQ5D) questionnaires (Primary outcome: SF36 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 5mm/5°), Moderate (5–10mm/5–10°), and Severe (> 10mm/> 10°). The minimal clinically important difference for SF36 PF score equals 12 points (1/2 of Standard deviation).

Results: Out of 660 patients screened at all four sites 70 met the inclusion criteria and were available for follow-up. The average follow-up was 20 months and an the average age was 71 years. Overall, there were 24/70 patients with none/mild femoral neck shortening, 25/70 with moderate shortening and 21/70 with severe shortening. Patients with severe shortening of their hip had significantly lower SF36 physical functioning scores (No/Mild vs. Severe shortening: 74 vs. 42 points, p=0.01). Similar important effects occurred with moderate shortening suggesting a gradient effect (No/Mild vs. Moderate shortening: 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).

Conclusion: 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.

We have studied the effect of shortening of the femoral neck and varus collapse on the functional capacity and quality of life of patients who had undergone fixation of an isolated intracapsular fracture of the hip with cancellous screws. After screening 660 patients at four university medical centres, 70 patients with a mean age of 71 years (20 to 90) met the inclusion criteria. Overall, 66% (46 of 70) of the fractures healed with > 5 mm of shortening and 39% (27 of 70) with > 5° of varus. Patients with severe shortening of the femoral neck had significantly lower short form-36 questionnaire (SF-36) physical functioning scores (no/mild (< 5 mm) vs severe shortening (> 10 mm); 74 vs 42 points, p < 0.001). A similar effect was noted with moderate shortening, suggesting a gradient effect (no/mild (< 5 mm) vs moderate shortening (5 to 10 mm); 74 vs 53 points, p = 0.011). Varus collapse correlated moderately with the occurrence of shortening (r = 0.66, p < 0.001). Shortening also resulted in a significantly lower EuroQol questionnaire (EQ5D) index scores (p = 0.05). In a regression analysis shortening of the femoral neck was the only significant variable predictive of a low SF-36 physical functioning score (p < 0.001).