Knee function after complex femoral fractures treated with interlocking nails.
 Twenty-three complex femoral fractures were treated with interlocking nails.
 After fracture healing, knee function was analyzed, including alignment, quadriceps and hamstring strength, thigh atrophy, and range of motion (ROM).
 Similar to previous studies in the preinterlocking nail era, knee function was impaired in comparison with the contralateral limb.
 Seventy-three percent of patients had decreased quadriceps strength, and 60% had decreased hamstring strength.
 Sixty-five percent had thigh atrophy.
 The ROM and alignment were satisfactory.
 Despite the advantages of early ROM with femoral fractures treated with interlocking nails, knee function is often unsatisfactory once fracture union has occurred.
 Therefore, a formal knee rehabilitation program is recommended to achieve an optimal result.
