Few studies exist of abdominal-wall function after reconstruction using a free transverse rectus abdominis musculocutaneous (TRAM) flap, compared to the deep inferior epigastric perforator (DIEP) flap. One study found that a DIEP flap reduced the strength deficit caused by the free TRAM flap. Another study found a significant reduction in strength to flex and to rotate the upper trunk in the TRAM flap group, compared to the DIEP flap group. The purpose of this study was to measure abdominal strength and to compare the results from the TRAM and DIEP flap groups.
Abdominal strength was measured in 32 patients who had a unilateral breast reconstruction in 2003, using a free muscle-sparing TRAM flap (n = 15) or a DIEP flap (n = 17). A DIEP flap was raised, if possible; however, the procedure was converted to a muscle-sparing TRAM flap, if it was found that more than two perforators were required for a DIEP flap based on clinical evaluation of perfusion. All surgery was performed by the same surgeon. Abdominal muscle strength was measured as concentric, eccentric, and isometric muscle strength using an isokinetic dynamometer. The standard test consists of three repetitions for both concentric and eccentric muscle strength and five repetitions for isometric muscle strength. All tests were performed in a sitting position. The best of three repetitions was chosen as maximal concentric or eccentric muscle strength (peak torque), and the best of five for isometric (peak torque).
No significant reduction in muscle strength was observed for concentric or isometric muscle strength; however, a significant lower eccentric muscle strength (adjusted for body weight) was found in the TRAM group (n = 15), compared to the DIEP group (n = 17) (123.8 Nm vs. 135.4 NM, p = 0.05). A 95% confidence interval on the difference ranged from 23.2 Nm to 0.007 Nm.
There was no significant difference in abdominal strength between the two flap groups at low-to-moderate work intensity, but at greater work intensity (eccentric muscle strength), the patients reconstructed using a DIEP flap had a significant advantage over the patients reconstructed using a muscle-sparing TRAM flap.
