Determination of sagittal alignment measurements in distal femurs

Open reduction and internal fixation is presently the treatment of choice for distal femur fractures. Anatomic reconstruction of the articular surface and restoration of biomechanical relations to the diaphysis are desired. A method to determine sagittal alignment on plain radiographs is warranted.

Consecutive adult, normal, distal femur/knee, plain lateral radiographs and scanned and digitalized cadaveric distal femurs were analyzed. Measurement of 7 different angles was performed.

Ninety-four adults [39 men (41.5%) and 55 women (58.5%)] with a mean age of 54 years (range, 18-92 years) and body mass index (BMI) of 29.7 kg/m(2) (range, 16.6-47.2 kg/m(2)), as well and 35 cadaveric femora [24 men (68.6%) and 11 women (31.4%)] with a mean age of 53 years (25-85 years) and BMI of 29.8 kg/m(2) (17.7-53.3 kg/m(2)) were studied. Twenty-two of the patients (23.4%) had radiographic findings of arthrosis. If arthrosis was diagnosed, measurements including the proximal rim of the articular surface were significantly greater (P = 0.001). Two angles were significantly smaller in women (P < 0.05). No significant differences in any measurement for age or BMI were recorded.

The necessity for reliability and quality of intraoperative and postoperative radiographic controls of the obtained fracture reduction, implant insertion, and final healed fracture increases with popularity of less invasive indirect reduction and stabilization methods. The ability to obtain exact sagittal alignment measurements has been problematic with other studies. Two different and reliable methods of measuring sagittal plane anatomy and measurements independent of implants were confirmed using plain radiographic images.