A new measurement for posterior tilt predicts reoperation in undisplaced femoral neck fractures: 113 consecutive patients treated by internal fixation and followed for 1 year

Abstract

Background and purpose: Preoperative posterior tilt in undisplaced (Garden I-II) femoral neck fractures is thought to influence rates of reoperation. However, an exact method for its measurement has not yet been presented. We designed a new measurement for posterior tilt on preoperative lateral radiographs and investigated its association with later reoperation.

Patients and methods: A consecutive series of 113 patients, > or = 60 years of age with undisplaced (Garden I-II) femoral neck fractures treated with two parallel implants, was assessed regarding patient characteristics, radiographs, and rate of reoperation within the first year. In a subgroup of 50 randomly selected patients, reliability tests for measurement of posterior tilt were performed.

Results: Intra- and interclass coefficients for the new measurement were > or = 0.94. 23% (26/113) of patients were reoperated and increased posterior tilt was an accurate predictor of failure (p = 0.002). 14/25 of posteriorly tilted fractures > or = 20 degrees were reoperated, as compared to 12/88 of fractures with less tilt (p < 0.001). In multiple logistic regression analysis including sex, age, ASA score, cognitive function, new mobility score, time from admission to operation, surgeon's expertise, postoperative reduction, and implant positioning, a preoperative posterior tilt of > or = 20 degrees was the only significant predictor of reoperation (p < 0.001).

Interpretation: The new measurement for posterior tilt appears to be reliable and able to predict reoperation in patients with undisplaced (Garden I-II) femoral neck fractures.

Figure 1.

Preoperative anterior-posterior and lateral radiographs of a 60-year-old male patient who sustained a Garden I–II femoral neck fracture. The posterior tilt is measured as the angle (α) between the mid-collum line (MCL) and the radius collum line (RCL), which is drawn from the center (c) of the caput circle to the crossing of the caput circle and the mid-collum line.

Figure 2.

Distribution of posterior tilt and rates of reoperation in the 113 patients who were operated on with internal fixation for a Garden I–II femoral neck fracture. Numbers in parenthesis are (reoperated patients / patients) in the relevant group.