An anatomic study of the distal femoral epiphysis.

BACKGROUND: The anatomy of the undulating distal femoral physis may be relevant to growth disturbance after physeal fractures and screw fixation about the physis. The surface anatomy of this physis has not been well described. METHODS: We performed an anatomic study on 26 cadaveric distal femoral epiphyses in specimens 3 to 18 years of age. High-resolution 3-dimensional surface scans were obtained and analyzed to determine the heights, approximate surface areas, and locations of the major undulations. RESULTS: Gross examination revealed lateral and anteromedial peripheral notches at the metaphyseal-epiphyseal junction, which deepen with advancing skeletal maturity. Within the epiphysis, there are 3 major undulations: a central ridge, lateral ridge, and medial peak, with mean heights of 5.5 mm (range, 2.9 to 9.8 mm), 2.5 mm (1.0 to 5.7 mm), and 2.9 mm (0.9 to 4.7 mm), respectively. The normalized height and surface area of each undulation decreased with increasing age, most dramatically in the central ridge. With respect to a line connecting the medial and lateral aspects of the physis, we found that the central peak passes more superior with younger age, and tends to be more posteriorly located. The lowest point of the physis is located either anteromedial or posterolateral. CONCLUSIONS: The central ridge, lateral ridge, and medial peak are the 3 major undulations in the distal femoral physis. The central ridge has the greatest height and most dramatic decrease in relative size with increasing age, suggesting structural importance. This anatomic data can guide metaphyseal and epiphyseal screw fixation. CLINICAL RELEVANCE: This study provides quantitative data on the topographic anatomy of the distal femoral physis, which can guide screw placement about the physis. These data may help identify fractures patterns with a greater risk of growth disturbance and key radiographic landmarks for guiding fracture reduction.