| Summary: | 博士 === 國立成功大學 === 健康照護科學研究所 === 101 === Background and purpose: The unilateral transverse rectus abdominis musculocutaneous (TRAM) flap is a major operation widely used for breast reconstruction. It is hypothesized that this surgery has the potential risk of weakening the abdominal wall because it disrupts the integrity of the rectus abdominis muscle (RA), therefore, alters the insertion of the oblique muscles and the biomechanical relationship between the RA muscle and adjacent structures. The purposes of this study were to examine the effects of the muscle-sparing (MS) unilateral TRAM flap surgery on muscle size of abdominal muscles, strength and endurance of trunk muscles, strength and endurance of core stability, as well as the postural responses during the performance of limb lifting movement or after an unexpected postural perturbation.
Methods: Forty women (aged 42.6 ± 6.2 yrs) after MS unilateral TRAM flap surgery and 30 healthy controls (aged 41.2 ± 4.9 yrs) participated. There were 3 experiments involved in this study. (1) Ultrasound imaging measured the thickness of all abdominal wall muscles and the cross-sectional area of the RA muscle at rest and in an isometric contraction. (2) Trunk strength was measured by a dynamometer and clinical tests (prone extension, curl-up and rotational curl-up). Endurance of trunk muscles and strength and endurance of core stability were measured by the clinical tests (abdominal muscle test for strength, unsupported double bend leg lifting for static endurance). (3) We recorded the biomechanical and electromyographic responses during voluntary limb movements and elicited by unexpected support surface translations and tilts in standing. A six-camera Qualisys motion system was used. Ground reaction forces and moments were acquired by a Kisler force plate. Surface electrodes were used to record the muscle activity of selected trunk and limb muscles.
Results: The results of 3 experiments were as follows: (1) 34 patients and 25 controls completed the first experiment. The remnant RA in the relaxed state was thinner and had a smaller cross-sectional area than those of the contracted state. The remnant RA in the relaxed state also was thinner than its contralateral intact counterpart. No differences in the thickness of other abdominal muscles were found between sides. The abdominal muscles in the TRAM group were smaller than those of the control group. (2) In the second experiment, all abdominal strength, endurance, and stabilizing ability measures in the TRAM group were less than those of the control group (p〈0.05). (3) 12 patients and 15 controls completed the third experiment. Between these two groups, no significant difference was observed in the maximum displacements of the center of mass and center of pressure in the anterior-posterior (COM A-P max and COP A-P max) and medial-lateral (COM M-L max and COP M-L max) directions. Main significant differences between the TRAM and control groups were observed in electromyographic (EMG) characteristics of abdominal muscles. 1) For arm raising tasks, relative muscle activity levels (percentage of maximal voluntary isometric contraction, normalized EMG) of the ipsilateral OEOP (obliquus externus abdominis on the side of the operated-RA) to the arm-raising side and bilateral OI (obliquus internus abdominis) muscles were higher in the TRAM group than those in the control group during the 4 arm rising tasks (p 〈 0.05). In addition, The temporal synchronization of bilateral homologous trunk muscle pairs showed a significant group effect in shoulder scaption at 90 degrees while holding a 1.5 kg weight (p=0.015). The TRAM group had higher degree of synchronization in the three trunk muscle pairs. 2) For leg lifting tasks, the TRAM group demonstrated higher muscle activation levels than those of the control group in OI of both sides and OEOP of the side ipsilateral to the leg-lifting in all four tasks. No difference was found in the degree of temporal synchronization between the TRAM and the control group (p〉0.05). 3) For unpredictable balance tasks, the EMG data showed no group difference in muscle activation levels of RA nonOP (the contralateral RA to the operation side), mean of bilateral OEs (OEbi-mean), and MFbi-mean (multifidus). However, the TRAM group demonstrated significantly higher levels of muscle activation level in the OIbi-mean than that in the control group. In addition, no group differences in the degree of temporal synchronization were found in all unexpected balance tasks.
Conclusion: The current study demonstrated that TRAM women had impairments in trunk muscle functions. There were decreases in strength and endurance of abdominal muscles, strength and endurance of core stability, and muscle size of the remnant RA and the other abdominal muscle in the women after TRAM surgery. Postoperative immobilization is the most likely cause of generalized weakness of the abdominal musculature. In addition, for limb lifting tasks, the TRAM patients had larger muscle activation levels in bilateral OI muscles and OE ipsilateral to the lifting limb side. Similar results were also observed in response to non-anticipatory postural adjustment tasks by standing a moveable platform.
Clinical Relevance: Based on findings of the current study physical therapists should be aware of the trunk functional deficits experienced by women after breast reconstruction with unilateral TRAM flap surgery. Further research is needed to design and implement appropriate physical therapy interventions.
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