Effect of integrity of the posterior cortex in displaced femoral neck fractures on outcome after surgical fixation in young adults

Aim: To assess whether disruption of the posterior cortex of intracapsular femoral fractures leads to an increased incidence of complications following closed reduction and internal fixation by multiple cannulated screws in young adults. Methods: A total of 146 consecutive adult patients with 146 femoral neck fractures were treated by closed reduction and internal fixation with parallel cannulated screw in inverted triangle or diamond configurations. All enrolled patients were divided into three groups: those with a non-displaced femoral neck fracture (Garden types I or II), those with a displaced femoral neck fracture (Garden types III or IV) but no posterior cortex disruption and those with a displaced femoral neck fracture (Garden types III or IV) and a disrupted posterior cortex. Results: Based on an average follow-up of 4.76 years (range, 2-6 years), displaced femoral neck fractures with a disrupted posterior cortex demonstrated an increased risk for avascular necrosis of the femoral head, shortening, redisplacement and conversion of prosthetic replacement as compared with those fractures without posterior cortex disruption (p = 0.002, 0.016, 0.001 and <0.0001, respectively). Conclusions: As compared with a femoral neck fracture with an intact posterior cortex, a displaced femoral neck fracture with a disrupted posterior cortex increases the risk for avascular necrosis, redisplacement and shortening and raises the likelihood that prosthetic replacement will be needed. Orthopaedic surgeons should be aware of this prognostic factor.