Function of the pectoralis major muscle after combined skin-sparing mastectomy and immediate reconstruction by subpectoral implantation of a prosthesis

For immediate subpectoral endoprosthetic breast reconstruction after skin-sparing mastectomy, the caudal origin of the major pectoral muscle is detached from the ribs and caudal part of the sternum. To date, the effect on the function of the major pectoralis muscle of this routine procedure is unknown. Therefore, we assessed the influence of the muscle's release on the upper-arm torque-strength profiles. Eighteen healthy controls and 10 women who had undergone unilateral immediate subpectoral prosthetic breast reconstruction underwent strength profile measurement by use of the Biodex System 3 Pro. The observations in the healthy controls were used to calculate the difference in torque strength between the dominant and nondominant side. This difference was used to correct the actual measurements in the operated women. In the controls, the torque strength at the dominant side was significantly stronger than that at the nondominant side (mean difference, 3.5 Nm, or 9.1%; P = 0.002). After subpectoral breast reconstruction, the measured torque strength at the operated side was 5.2 Nm, or 14% less than that at the nonoperated side (P = 0.001). After correction for the effect of dominance, we observed a significant reduction of 7.6 Nm, or 20.1% of torque strength at the operated side (P = 0.000). Because the strength loss is substantial, patients ought to be informed about the possible postoperative muscular deficit, surgeons should endeavor a minimum amount of pectoral release, and alternative procedures should be explored.