Cases: Two patients with short axial length proximal femur (ALPF) and undisplaced femoral neck fractures were treated with Femoral Neck System (FNS). The shortest produced implant was too long for both. The first patient was complicated with the implant indenting at the femoral head articular surface. In the second case, insertion with precollapsed technique, short-measure reaming, and leaving the barrel plate slightly off the lateral femoral cortex were necessary to achieve fixation successfully. Conclusion: CT scan should be done preoperatively for ALPF measurement in patients planned for surgical fixation with FNS. Precollapsed implantation, offset-plate technique, or a combination may help, but alternative fixation methods should be considered.