Gerdyʼs Tubercle: The Lighthouse to the Knee

OBJECTIVE:Identification of Gerdyʼs tubercle is the mainstay to any approach to the knee. Most surgical approaches to the proximal tibia and distal femur reference Gerdyʼs tubercle as a critical landmark. Its identification is therefore paramount. Unfortunately, the bony landmark can be skewed by soft tissue swelling, morbid obesity, or disruption from bony injury. The objective of this study was to determine a reliable way of identifying the normal anatomic location of Gerdyʼs tubercle using surrounding structures during any surgical approach to the knee. DESIGN:Anatomic cadaver study. SETTING:Academic laboratory center. MATERIALS AND METHODS:Twenty-four adult human cadaver lower extremities as 12 matched pairs were used. Systematic identification and measurement from the point of intersection of a line drawn between 2 corners of a box created using the tibial tubercle, inferior pole of the patella, and the fibula head were performed and recorded. MAIN OUTCOME MEASUREMENT:Mean distance from cutaneous point of intersection to Gerdyʼs tubercle upon dissection. RESULTS:The mean distance from the point of intersection to Gerdyʼs tubercle was 2.58 ± 2.01 mm with a range from 0 to 8. The mean distances for the right and left lower extremities were 2.67 ± 2.02 and 2.5 ± 2.11 mm, respectively. Statistical analysis using 2-tailed independent t test with a significance set at P