Quantity of lymph nodes correlates with improvement in lymphatic drainage in treatment of hind limb lymphedema with lymph node flap transfer in rats

Purpose This study was conducted to investigate the correlation between the number of vascularized lymph nodes (LN) transferred and resolution of hind limb lymphedema in a rat model. Methods Unilateral hind limb lymphedema was created in 18 male Sprague-Dawley rats following inguinal and popliteal LN resection and radiation. A para-aortic LN flap based on the celiac artery was subsequently transferred to the affected groin. The three study groups consisted of Group A (no LN transfer), Group B (transfer of a single vascularized LN), and Group C (transfer of three vascularized LNs). Volumetric analysis of bilateral hind limbs was performed using micro-CT imaging at 1, 2, and 3 months postoperatively. Lymphatic drainage was assessed with Tc⁹⁹ lymphoscintigraphy preoperatively and at 3 months postoperatively. Results A statistically significant volume reduction was seen in Groups B and C compared to Group A at all time points. Volume reduction of Group A vs.Group B at 1 month (8.6% ± 2.0% vs. 2.7% ± 2.6%, P < 0.05), 2 months (9.3% ± 2.2% vs. -4.3% ± 2.7%, P < 0.05), and 3 months (7.6% ± 3.3% vs. -8.9% ± 5.2%, P < 0.05). Volume reduction of Group A vs. Group C at 1 month (8.6% ± 2.0% vs. -6.6% ± 3.1%, P < 0.05), 2 months (9.3% ± 2.2% vs. -10.2% ± 4.6%, P < 0.05), and 3 months (7.6% ± 3.3% vs. -9.1% ± 3.1%, P < 0.05). Of note, comparison of Groups B and C demonstrated greater volume reduction in Group C at 1 (P < 0.02) and 2 (P = 0.07) months postoperatively. Conclusions LN flap transfer is an effective procedure for the treatment of lymphedema. The number of vascularized LNs transferred correlates positively with the degree of volume reduction.