Author(s): NATALUCCI, V.1, PAGANO, A.1, DUBINI, F.1, LENTI, E.1, ANDRENELLI, E.1, GERVASI, M.2, CERAVOLO, M.G.1, CAPECCI, M.1, Institution: UNIVERSITY OF MILAN, Country: ITALY, Abstract-ID: 2673

INTRODUCTION:
Axillary Lymph Node Dissection (ALND) is associated with long-term upper limb morbidity in breast cancer (BC) survivors. Targeted Axillary Dissection (TAD) is a more conservative approach that may reduce postoperative complications [1]. However, evidence on biomechanical and neuromuscular outcomes after TAD compared to ALND is limited.
METHODS:
Eighteen women (55.8±12 years), surgically treated for BC at least 6-month before assessment (591±339 days), were enrolled after ALDN or TAD. Functional outcomes included upper limb disability (QuickDASH), physical activity level (IPAQ-SF) and handgrip strength (HGS). Surface EMG (FREEEMG 1000, BTS Bioengineering) recorded pectoralis major (PM), middle deltoid (MD), biceps brachii (BB) and upper trapezius (UT) during five repetitions of forward shoulder flexion and abduction (5-s rest). Upper limb kinematics and gait during 6MWT were assessed using an IMU (G-sensor, BTS Bioengineering). Muscle mechanical properties were assessed using Myoton. Trapezius compensatory co-activation was estimated through the co-contraction index (CCI) [2].
Participants were retrospectively allocated to the ALND and TAD groups and non-parametric statistics used for between-group (Mann–Whitney U test) and intra-group comparisons (Wilcoxon matched pair test).
RESULTS:
ALND patients were older (p=.018) and had more removed lymph nodes (p=.04).
Neoadjuvant therapies were more frequent in TAD group (p<.001), whereas adjuvant hormonal therapy was more common in ALND (p=.01). Late surgical complications were more frequent after ALND (p=.04), including shoulder pain, hypofunction and hand paresthesia.
Despite comparable physical activity levels, ALND group showed a trend toward worse functional outcomes, with higher QuickDASH scores (median 34 vs 10 in TAD) and lower 6MWT performance. QuickDASH score was associated with number of removed lymph nodes (p=.04), operated-side shoulder flexion ROM (p=.02), CCI during shoulder flexion (p=.006), and HGS (p=.05).
Both groups showed altered shoulder movement patterns with reduced ROM and less smooth (higher jerk). EMG revealed abnormal PM activation during abduction (p=.04), associated with reduced MD activity (p=.04). In ALND, PM contribution during flexion-extension was reduced on the operated side (p=.03), while UT activation remained bilaterally increased (p=.04). CCI was higher on the operated side, especially in ALND (p=.03). Myoton showed higher PM decrement in ALND (p=.03), indicating reduced elasticity.
CONCLUSION:
Both ALND and TAD are associated with neuromuscular alterations after BC surgery. However, ALND appears linked to more late complications, greater trapezius compensatory co-contraction, and reduced pectoralis elasticity, potentially contributing to higher disability. These findings support the need for targeted rehabilitation.
[1] Che Bakri et al. (2023), 277(4), 572–580.
[2] Unnithan et al. (1996), 36(8), 487–494.