The Epiphyseal Scar as a Radiographic Landmark for Retrograde Femoral Nail Insertion

The purpose of this study was to examine the epiphyseal scar and its relationship to the intercondylar notch on anteroposterior (AP) radiographs of the knee and to establish its usefulness with retrograde femoral nail insertion.

AP radiographs of 100 skeletally mature (50 male and 50 female) knees were used for measurements of the distance from the intercondylar notch to the epiphyseal scar. This data was correlated with intraoperative findings on 34 consecutive patients who underwent retrograde nail insertion. For men, the mean distance from the intercondylar notch to the epiphyseal scar on a “true” AP radiograph averaged 18.55 mm (range, 15.4- 24.9 mm). For women, the mean distance measured 16.61 mm (range, 13.2-21.8 mm). Clinical intraoperative correlation revealed that all nails were inserted deep to the articular cartilage and that no intramedullary nails were prominent.

The use of the epiphyseal scar on the AP fluoroscopic view as a landmark for the placement of the most distal interlocking screw of the nail ensures extra-articular nail placement. Good visualization of the epiphyseal scar and an understanding of nail geometry can assist in proper retrograde femoral intramedullary nail insertion without direct visualization of the entry site.