THE FATE OF THE OBLIQUE ABDOMINAL MUSCLES AFTER FREE TRAM FLAP SURGERY

During recent years, clinical research on the donor site morbidity aft er free or pedicled transverse rectus abdominis myocutaneous (TRAM) fl ap surgery has been focusing on the reduced flexion capacity of the ab dominal wall. However, the rectus abdominis muscles have close interac tions with their synergists and antagonists and collaborate with their neighbouring muscles. The purpose of this study was to examine the co nsequences of partially resecting the rectus abdominis muscle on the d ifferent muscle groups of the abdominal wall. Twenty free TRAM flap pa tients, 12-61 months (mean 32.1 months) after surgery, were clinically examined, evaluated for curl-up performance and underwent isokinetic dynamometry for flexion, extension and rotation. The patients were com pared with 20 non-operated controls. Nineteen patients answered a ques tionnaire. Abdominal wall abnormalities occurred in 10 patients: umbil ical asymmetry (n = 3), abdominal wall asymmetry (n = 4), lower abdomi nal bulging (n = 2) and hernia (n = 1). Curl-up performance was less i n the TRAM flap patients (P = 0.001, Mann-Whitney). Isokinetic flexion , extension and rotation were also less in the TRAM flap patients (Fis her's exact test). This study indicates that what has been believed to be 'limited' surgical damage to the abdominal wall leads to an import ant reduction in flexion strength but to an even more important reduct ion of rotation strength due to bilateral displacement and damage of t he insertion of the oblique muscles. Partial compensation by synergist s is variable and unpredictable on an individual basis. These function al disorders can potentially lead to important changes in activities o f daily life.