Does Dangling the Lower Extremity after Free Flap Reconstruction Reduce Partial Flap Loss? A RCT

Phil Hanwright
Jul 2
2 min read

PMID: 39636700

Plast Reconstr Surg. 2025 Jul 1;156(1):162-169.

Key Takeaways

Unrestricted limb positioning after POD 7 is as safe as a formal dangling protocol (also beginning POD 7) for preventing partial flap loss in lower‑extremity free flaps.
No meaningful differences were observed in hospital stay, major complications, or minor wound events.

Background

Venous congestion is a potential cause of partial flap loss after lower‑extremity free‑flap reconstruction. Graduated dangling protocols are intended to condition venous outflow but may prolong hospitalization and vary across institutions.

Objective

To determine whether allowing the leg to hang freely from postoperative day (POD) 7 onward is non‑inferior—that is, no worse than—a standard graduated dangling protocol for preventing partial flap loss.

Methods

Design: Multicenter, parallel‑group, randomized non‑inferiority trial conducted at four tertiary centers in the Netherlands.
Target enrollment: 130 patients (80 % power, one‑sided α = 0.025) with a non‑inferiority margin of 12 % absolute risk difference in partial flap loss.
Participants: Adults ≥ 18 years undergoing primary lower‑extremity free‑flap reconstruction for trauma, tumor resection, or chronic infection.
Randomization: On POD 7, concealed 1:1 allocation to
1. Graduated dangling protocol – four sessions per day starting at 5 min and increasing to 30 min by POD 10.
2. Unrestricted positioning – sitting, standing, and ambulation without time limits.
Primary outcome: Partial flap necrosis requiring operative debridement within 6 weeks.
Secondary outcomes: Complete flap loss, DVT/PE, surgical‑site infection, split‑thickness graft take, and hospital length of stay through 90 days.
Statistical analysis: Risk differences with Agresti‑Caffo 95 % confidence intervals; non‑inferiority declared if the upper CI bound was < 12 %.
- Preplanned interim analyses at 25 % and 50 % enrollment led to early stopping at 75 participants after the non‑inferiority boundary was crossed.

Results

Partial flap loss: 2 / 39 patients (5.1 %) in the dangling group versus 1 / 36 patients (2.8 %) in the no‑dangling group. The difference is roughly 2 extra cases per 100 patients and remains well within the pre‑set 12 % safety margin, so skipping dangling was considered equally safe.
Complete loss: None in either arm.
Median length of stay: 14 days with dangling vs 13 days without (no statistical difference).

Conclusion

Foregoing a formal dangling regimen from POD 7 onward does not increase partial flap necrosis and simplifies postoperative care.

Strengths and Limitations

Strengths

Randomized multicenter design, prespecified safety margin, blinded outcome review.

Limitations

Many centers now initiate dangling as early as POD 3 (PMID: 39750583), so both study arms represent relatively late protocols.
Trial stopped early at 75 of the planned 130 patients, so small differences may have been missed.
- The acceptable safety margin (12 %) is quite generous.

Future Directions

Evaluate benefits of even earlier unrestricted positioning (POD 3–5).
Consider incorporating tissue oximetry for individualized mobilization protocols.