Re-evaluation of Garden indexes as a criterion for reduction of femoral neck fracture: a cadaveric study

Objective To investigate whether the Garden indexes can serve as a criterion for rotational displacement of femoral neck fracture. Methods Ten cadaveric specimens of healthy human proximal femur were used for this study. They came from 3 males and 2 females who had died at the age from 45 to 70 years old. A Kirschner wire of 2.0 mm in diameter was implanted into the center of the femoral head. Osteotomy was conducted perpendicular to the middle line of the femoral neck. The rotational angles were marked on the distal osteotomy surface. Each cadaveric specimen was rotated sequentially at pronation and supination angles of 0°, 10°, 20°, 30°, 40°, 50°, 70° and 90°, respectively. X-ray images of anterior-posterior and lateral views were taken to record all the rotations of the specimens. Picture Archiving and Communication Systems (PACS) were used to measure the Garden indexes and compare them among anterior-posterior and lateral X-ray films of different pronation and supination angles. Changes in the area of the femoral head fovea at different rotation angles were observed as well. Results There were no significant differences in the auterior-posterior or latera Garden indexes from 0° to pronation or supination 30°, with all the Garden values >155° (P>0.05); from pronation of 40° to pronation of 90°, the Garden indexes were 152.36°±1.41°, 146.04°±1.64°, 143.95°±0.60° and 141.73°±0.60° for anterior-posterior views and 172.54°±0.86°, 168.57°±0.98°, 157.18°±1.17° and 156.47°±1.63° for lateral views, showing a significant difference between rotational angles (P<0.05); from supination of 40° to supination of 90°, the Garden indexes were 151.67°±1.06°, 147.32°±1.82°, 142.77°±0.75° and 139.88°±1.48° for anterior-posterior views and 172.28°±0.79°, 166.76°±1.02°, 155.67°±1.74° and 154.16°±1.27° for lateral views, showing a significant difference between rotational angles (P<0.05). The area of the femoral head fovea decreased gradually with the increase in pronation angle, and increased gradually with the increase in supination angle. Conclusions The Garden indexes cannot serve as an accurate indication of rotational displacement in reduction of femoral neck fracture when the pronation or supination angles ranges from 0° to 30°. Changes in the area of the femoral head fovea can help determine the rotational displacement of the femoral neck fracture. Key words: Femoral neck fractures; Reduction; Garden indexes; Rotational displacement