PECTORALIS MAJOR TENDON AS A REFERENCE FOR RESTORING HUMERAL LENGTH AND RETROVERSION WITH HEMIARTHROPLASTY FOR FRACTURE

Abstract

Purpose of study was to determine the value of the upper edge of the pectoralis major (UPM) insertion as landmark to determine proper height and version of hemiarthroplasties implanted for proximal humeral fractures.

UPM insertion was referenced with metallic device in 20 cadaveric humerus. Computed Tomography study was performed in all specimens. Total humeral length and distance between the UPM insertion and the tangent to humeral head was recorded. CT scan slice showing UPM superimposition in humeral head was drawn to determine prosthesis retroversion. Qualitative variables are presented in absolute and percentage values. Quantitative variables are presented with mean values and standard deviation.

Mean total humeral length 32,13 cm. Mean distance from the UPM to the tangent to the humeral head 5,64. Mean distance from UPM insertion to the tangent to the humeral head represents the 17,55 % of total humeral length. Mean distance of UPM insertion to the posterior fin of the prosthesis of 1,06 cm. Angle between UPM insertion and posterior fin of the prosthesis 24,65°.

Mean distance from the UPM insertion to the top of the humeral head of 5, 6 cm with a 95% confidence interval. Placement of the prosthesis in the proper retroversion can be achieved by placing the posterior fin 1,06 cm posterior to the UPM or by placing the posterior fin at 24,65° with respect to the upper insertion line. UPM constitutes a reliable reference to reproduce anatomy in hemiarthroplasties for proximal humeral fractures.