Prognostic Value of Posterior Tilt Angle in Determining Outcome of Internal Fixation of Nondisplaced Femoral Neck Fractures

INTRODUCTION: As the population continues to age there is expected to be an increase in prevalence of femoral neck fractures. The standard tool for guiding treatment decisions in femoral neck fractures is the Garden Classification, which is based around the severity of displacement. Garden I and II fractures display minimal displacement and suggest internal fixation as the preferred surgical option rather than arthroplasty. Recent literature indicates the rate of revision surgery following internal fixation of Garden I and II fractures is approximately 20%. Originally proposed by Palm et al, Posterior Tilt Angle (PTA) is a radiographic measurement that evaluates the severity of angulation at the site of femoral neck fracture. Measured on a lateral radiograph of the hip, the PTA consists of the angle between the mid-column line and the radius column line. Palm suggested the PTA has prognostic value in determining the outcome of internal fixation of femoral neck fractures, with 20 degrees being the cut off angle. The goal of this systematic review is to determine association between preoperative PTA and the risk of failure after internal fixation of nondisplaced femoral neck fractures. METHODS: This systematic review was conducted following PRISMA guidelines. Quality appraisal was conducted using the MINORS criteria and all data from the included studies was manually extracted and summarized. Outcomes of interest included development of malunion, nonunion, avascular necrosis, loss of fixation, and reoperation requirement. A full text review of 40 studies was conducted after inclusion and exclusion criteria were applied and a total of 17 studies were included in the systematic review. RESULTS: Treatment failure was observed in 14% of cases. PTA ≥20° had a failure rate of 24%, compared to 12% for CONCLUSION: The Posterior Tilt Angle is a useful measurement in predicting internal fixation failure of Garden I and II femoral neck fractures. There is a significantly higher rate of failure for internal fixation when the PTA is greater than 20 degrees. In these cases, arthroplasty may be a better treatment option. Study of PTA as a continuous variable is recommended to determine the true critical value