Garden type I fractures include incomplete fractures and impacted fractures. With advances in scientific technology and medical treatment, certain deficiencies of the Garden classification have become apparent. The authors hypothesized that the incidence of incomplete femoral neck fractures was low and that impacted femoral neck fractures were not undisplaced and stable fractures. A new method was developed to precisely measure the spatial displacement of the femoral head in impacted femoral neck fractures. Between 2008 and 2011, nine hundred sixty-six patients with femoral neck fractures were treated, 48 of whom had Garden type I fractures, as seen on anteroposterior radiographs. Seven fractures were classified as incomplete on radiographs; however, after 3-dimensional reconstruction, 3 were classified as incomplete and 4 as complete fractures. Furthermore, the remaining 41 Garden I fractures that were classified as impacted on radiographs showed large spatial displacement on 3-dimensional reconstruction. The average rotational displacement of the femoral head was 19.29°±10.51°, and the average displacements of the femoral head center and the lowest point of the fovea capitis were 8.76±4.45 and 14.39±8.08 mm, respectively. This study showed that the incidence of incomplete femoral neck fractures was low. Impacted femoral neck fractures showed variable degrees of displacement and were not undisplaced, stable fractures. Garden classification for impacted femoral neck fractures has certain limitations. Impacted femoral neck fractures should be differentiated from Garden type I fractures so clinicians can select appropriate treatments for these fractures.