Can Whitnall’s tubercle be localized using palpable landmarks around the orbit?

Objectives: Whitnall’s tubercle (WT) is located deep in the lateral canthus and on the lateral orbital wall and has crucial structures attach to it. We aimed to define the location of WT using the palpable bone landmarks which can be used as reliable landmarks in eyelid and orbital surgery to prevent the damage of stuctures associated with WT. Methods: Forty-four adult skulls (22 right, 22 left) were included to the study. The skulls were divided into two groups according to the apparancy of the WT. The distances from WT to the frontozygomatic suture, the marginal tubercle, the anterior point of the zygomatic arch, and the lateral margin of the orbit were measured. The clock positions of WT according to the marginal tubercle and the anterior point of the zygomatic arc were determined. Results: The distances of the WT to the marginal tubercle, the anterior point of the zygomatic arch, the lateral margin of the orbit, and the frontozygomatic suture were 9.92±1.65 mm, 16.48±1.86 mm, 2.32±0.53 mm and 9.66±1.44 mm, respectively. WT was at 8 and 9 o’clock positions on the left, and at 4, 3, and 2 o’clock positions on the right according to the marginal tubercle. WT was at 10 o’clock position on the left, and 2 and 1 o’clock positions on the right according to the anterior point of the zygomatic arch. Conclusion: The marginal tubercle, the lateral margin of the orbit, and the anterior point of the zygomatic arch can be used as standart bony landmarks in eyelid and orbital surgery to prevent the soft tissue damage relevant to WT. The high kappa values of the interclass and intraclass correlations suggest that these parameters are reliable and repeatable for clinical use. Out of these parameters, the anterior point of the zygomatic arch is more beneficial to locate the WT because of the standard clock positions. The WT is typically located at 10 o’clock position on the left and 2 o’clock position on the right according to the anterior point of the zygomatic arch.